AADAC Arylacetamide deacetylase displays cellular triglyceride lipase activity in liver, increases the levels of intracellular fatty acids derived from the hydrolysis of newly formed triglyceride stores and plays a role in very low-density lipoprotein assembly. Displays serine esterase activity in liver. Deacetylates a variety of arylacetamide substrates, including xenobiotic compounds and procarcinogens, converting them to the primary arylamide compounds and increasing their toxicity. NCEH1 KIAA1363 AADACL1 NCEH1 neutral cholesterol ester hydrolase 1.is highly expressed in invasive cancer cells and is the major protein in mouse brain diethylphosphorylated . Sequence similarities between hormone-sensitive lipase and prokaryotic enzymes was dicovered by Langin and Holm and Hemila et al.
BACKGROUND: The prognosis of Borrmann type III advanced gastric cancer (AGC) is known to vary significantly among patients. This study aimed to determine which differentially expressed genes (DEGs) are directly related to the survival time of Borrmann type III AGC patients and to construct a prognostic model. METHODS: We selected 25 patients with Borrmann type III AGC who underwent radical gastrectomy. According to the difference in overall survival (OS), the patients were divided into group A (OS<1 year, n=11) and group B (OS>3 years, n=14). DEGs related to survival time in patients with Borrmann type III AGC were determined by mRNA sequencing. The prognosis and functional differences of DEGs in different populations were determined by The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) public databases. The expression of mRNA and protein in cell lines was detected by quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) and Western blot (WB). Immunohistochemical (IHC) staining was used to detect protein expression in the paraffin-embedded tissues of 152 patients with Borrmann type III AGC who underwent radical gastrectomy. After survival analysis, nomograms were constructed to predict the prognosis of patients with Borrmann type III AGC. RESULTS: Arylacetamide deacetylase (AADAC) is a survival-related DEG in patients with Borrmann type III AGC. The higher the expression level of its mRNA and protein is, the better the prognosis of patients. Bioinformatics analysis found that AADAC showed significant differences in prognosis and function in European and American populations and Asian populations. In addition, the mRNA and protein expression levels of AADAC were high in differentiated gastric cancer (GC) cells. We also found that AADAC was an independent prognostic factor for patients with Borrmann type III AGC, and its high expression was significantly correlated with better OS and disease-free survival (DFS). Nomogram models of AADAC expression level combined with clinicopathological features can be used to predict the OS and DFS of Borrmann type III AGC. CONCLUSION: AADAC can be used as a biomarker to predict the prognosis of Borrmann type III AGC and has the potential to become a new therapeutic target for GC.
Title: Arylacetamide Deacetylase Is Involved in Vicagrel Bioactivation in Humans Jiang J, Chen X, Zhong D Ref: Front Pharmacol, 8:846, 2017 : PubMed
Vicagrel, a structural analog of clopidogrel, is now being developed as a thienopyridine antiplatelet agent in a phase II clinical trial in China. Some studies have shown that vicagrel undergoes complete first-pass metabolism in human intestine, generating the hydrolytic metabolite 2-oxo-clopidogrel via carboxylesterase-2 (CES2) and subsequently the active metabolite H4 via CYP450s. This study aimed to identify hydrolases other than CES2 that are involved in the bioactivation of vicagrel in human intestine. This study is the first to determine that human arylacetamide deacetylase (AADAC) is involved in 2-oxo-clopidogrel production from vicagrel in human intestine. In vitro hydrolytic kinetics were determined in human intestine microsomes and recombinant human CES and AADAC. The calculated contribution of CES2 and AADAC to vicagrel hydrolysis was 44.2 and 53.1% in human intestine, respectively. The AADAC-selective inhibitors vinblastine and eserine effectively inhibited vicagrel hydrolysis in vitro. In addition to CES2, human intestine AADAC was involved in vicagrel hydrolytic activation before it entered systemic circulation. In addition, simvastatin efficiently inhibited the production of both 2-oxo-clopidogrel and active H4; further clinical trials are needed to determine whether the hydrolytic activation of vicagrel is influenced by coadministration with simvastatin. This study deepens the understanding of the bioactivation and metabolism properties of vicagrel in humans, which can help further understand the bioactivation mechanism of vicagrel and the variations in the treatment responses to vicagrel and clopidogrel.
Title: Comparison of substrate specificity among human arylacetamide deacetylase and carboxylesterases Fukami T, Kariya M, Kurokawa T, Iida A, Nakajima M Ref: Eur J Pharm Sci, 78:47, 2015 : PubMed
Human arylacetamide deacetylase (AADAC) is an esterase responsible for the hydrolysis of some drugs, including flutamide, indiplon, phenacetin, and rifamycins. AADAC is highly expressed in the human liver, where carboxylesterase (CES) enzymes, namely, CES1 and CES2, are also expressed. It is generally recognized that CES1 prefers compounds with a large acyl moiety and a small alcohol or amine moiety as substrates, whereas CES2 prefers compounds with a small acyl moiety and a large alcohol or amine moiety. In a comparison of the chemical structures of known AADAC substrates, AADAC most likely prefers compounds with the same characteristics as does CES2. However, the substrate specificity of human AADAC has not been fully clarified. To expand the knowledge of substrates of human AADAC, we measured its hydrolase activities toward 13 compounds, including known human CES1 and CES2 substrates, using recombinant enzymes expressed in Sf21 cells. Recombinant AADAC catalyzed the hydrolysis of fluorescein diacetate, N-monoacetyldapsone, and propanil, which possess notably small acyl moieties, and these substrates were also hydrolyzed by CES2. However, AADAC could not hydrolyze another CES2 substrate, procaine, which possesses a moderately small acyl moiety. In addition, AADAC did not hydrolyze several known CES1 substrates, including clopidogrel and oseltamivir, which have large acyl moieties and small alcohol moieties. Collectively, these results suggest that AADAC prefers compounds with smaller acyl moieties than does CES2. The role of AADAC in the hydrolysis of drugs has been clarified. For this reason, AADAC should receive attention in ADMET studies during drug development.
Serine hydrolase KIAA1363 is an acetyl monoalkylglycerol ether (AcMAGE) hydrolase involved in tumor cell invasiveness. It is also an organophosphate (OP) insecticide-detoxifying enzyme. The key to understanding these dual properties was the use of KIAA1363 +/+ (wildtype) and -/- (gene deficient) mice to define the role of this enzyme in brain and other tissues and its effectiveness in vivo in reducing OP toxicity. KIAA1363 was the primary AcMAGE hydrolase in brain, lung, heart and kidney and was highly sensitive to inactivation by chlorpyrifos oxon (CPO) (IC50 2 nM) [the bioactivated metabolite of the major insecticide chlorpyrifos (CPF)]. Although there was no difference in hydrolysis product monoalkylglycerol ether (MAGE) levels in +/+ and -/- mouse brains in vivo, isopropyl dodecylfluorophosphonate (30 mg/kg) and CPF (100 mg/kg) resulted in 23-51% decrease in brain MAGE levels consistent with inhibition of AcMAGE hydrolase activity. On incubating +/+ and -/- brain membranes with AcMAGE and cytidine-5'-diphosphocholine, the absence of KIAA1363 activity dramatically increased de novo formation of platelet-activating factor (PAF) and lyso-PAF, signifying that metabolically-stabilized AcMAGE can be converted to this bioactive lipid in brain. On considering detoxification, KIAA1363 -/- mice were significantly more sensitive than +/+ mice to ip-administered CPF (100 mg/kg) and parathion (10 mg/kg) with increased tremoring and mortality that correlated for CPF with greater brain acetylcholinesterase inhibition. Docking AcMAGE and CPO in a KIAA1363 active site model showed similar positioning of their acetyl and trichloropyridinyl moieties, respectively. This study establishes the relevance of KIAA1363 in ether lipid metabolism and OP detoxification.
Most of the triacylglycerol (TAG) utilized for the assembly of very-low-density lipoprotein (VLDL) in the secretory apparatus of the hepatocyte is mobilized by lipolysis of the cytosolic TAG pool, followed by re-esterification. The lipases involved include arylacetamide deacetylase and/or triacylglycerol hydrolase. Some of the re-esterified products of lipolysis gain access to an apolipoprotein-B-rich VLDL precursor to form mature VLDL. Some, however, are returned to the cytosolic pool in a process that is stimulated by insulin and inhibited by microsomal triacylglycerol transfer protein (MTP). Phospholipids also contribute to VLDL TAG in a process which involves ADP-ribosylation factor-1 (ARF-1)-mediated activation of phospholipase D. The temporary storage of TAG in the liver, followed by its mobilization and secretion as VLDL, form part of a process by which the liver protects vulnerable body tissues from excess lipotoxic non-esterified ('free') fatty acids in the plasma.
Title: Human liver arylacetamide deacetylase: Molecular cloning of a novel esterase involved in the metabolic activation of arylamine carcinogens with high sequence similarity to hormone sensitive lipase Probst MR, Beer M, Beer D, Jenoe P, Meyer UA, Gasser R Ref: Journal of Biological Chemistry, 34:21650, 1994 : PubMed
Microsomal arylacetamide deacetylase (DAC) competes against the activity of cytosolic arylamine N-acetyltransferase, which catalyzes one of the initial biotransformation pathways for arylamine and heterocyclic amine carcinogens in many species and tissues. Activity determination and immunoblot analysis of DAC in human target tissues for arylamine carcinogens revealed that in extrahepatic tissues, additional enzymes are responsible for any deacetylation activity, whereas a single enzyme predominantly catalyzes this hydrolytic reaction in liver. We isolated and characterized a full-length cDNA from a human liver lambda gt11 library. This clone encodes an open reading frame of 400 amino acids with a deduced molecular mass of 45.7 kDa and contains two putative glycosylation sites. The 3'-untranslated region contains two putative polyadenylation signals. The cDNA was confirmed to be that for DAC in tryptic peptides from the purified human liver protein. Highest sequence similarity of DAC was found in a series of prokaryotic esterases encompassing the putative active site. Two extended regions of significant sequence homology with hormone-sensitive lipase and with lipase 2 from Moraxella TA144 were identified, whereas similarity to carboxyl esterases was restricted to the region encompassing the putative active site, indicating that DAC should be classified as esterase. This cDNA provides an important tool to study deacetylation and its effects on the metabolic activation of arylamine and heterocyclic amine carcinogens.
Extracted from Hormone sensitive lipases. BD-FAE: The function of many members may differ from the one of the representavive used to describe the family in the PFAM database. (from PFAM): This family represents a novel bifunctional feruloyl and acetyl xylan esterase (BD-FAE, previously known as bifunctional carbohydrate esterase (CE)), which is active on complex natural xylans and was identified as the basis of a monophyletic clade gathering all homologs identified in PULs (polysaccharide utilisation loci) predicted to act on xylan. It adopts an alpha-beta-hydrolase fold with the catalytic triad Ser-Asp-His. This new family of proteins is a new candidate for biomass processing due to its capacity to remove ferulic acid and acetic acid from natural corn and birchwood xylan substrates. In PFAM database it includes family Tannase_Bact and family Est9X which are separate families in ESTHER. Feruloyl esterases are distributed in different sub-classes type-A B C,D and E and fall respectively in the following families. Type-A in Lipase_3, Type-B in Esterase_phb (PHB depolymerase), Type-C in Tannase, Type-D in FaeC, Type-E in A85-Feruloyl-Esterase, Type-F in BD-FAE
Organophosphorous nerve agents (OPNA) pose an actual and major threat for both military and civilians alike, as an upsurge in their use has been observed in the recent years. Currently available treatments mitigate the effect of the nerve agents, and could be vastly improved by means of scavengers of the nerve agents. Consequently, efforts have been made over the years into investigating enzymes, also known as bioscavengers, which have the potential either to trap or hydrolyze these toxic compounds. We investigated the previously described esterase 2 from Thermogutta terrifontis (TtEst2) as a potential bioscavenger of nerve agents. As such, we assessed its potential against G-agents (tabun, sarin, and cyclosarin), VX, as well as the pesticide paraoxon. We report that TtEst2 is a good bioscavenger of paraoxon and G-agents, but is rather slow at scavenging VX. X-ray crystallography studies showed that TtEst2 forms an irreversible complex with the aforementioned agents, and allowed the identification of amino-acids, whose mutagenesis could lead to better scavenging properties for VX. In conjunction with its cheap production and purification processes, as well as a robust structural backbone, further engineering of TtEst2 could lead to a stopgap bioscavenger useful for in corpo scavenging or skin decontamination.
BACKGROUND: Nowadays there is a strong trend towards a circular economy using lignocellulosic biowaste for the production of biofuels and other bio-based products. The use of enzymes at several stages of the production process (e.g., saccharification) can offer a sustainable route due to avoidance of harsh chemicals and high temperatures. For novel enzyme discovery, physically linked gene clusters targeting carbohydrate degradation in bacteria, polysaccharide utilization loci (PULs), are recognized 'treasure troves' in the era of exponentially growing numbers of sequenced genomes. RESULTS: We determined the biochemical properties and structure of a protein of unknown function (PUF) encoded within PULs of metagenomes from beaver droppings and moose rumen enriched on poplar hydrolysate. The corresponding novel bifunctional carbohydrate esterase (CE), now named BD-FAE, displayed feruloyl esterase (FAE) and acetyl esterase activity on simple, synthetic substrates. Whereas acetyl xylan esterase (AcXE) activity was detected on acetylated glucuronoxylan from birchwood, only FAE activity was observed on acetylated and feruloylated xylooligosaccharides from corn fiber. The genomic contexts of 200 homologs of BD-FAE revealed that the 33 closest homologs appear in PULs likely involved in xylan breakdown, while the more distant homologs were found either in alginate-targeting PULs or else outside PUL contexts. Although the BD-FAE structure adopts a typical alpha/beta-hydrolase fold with a catalytic triad (Ser-Asp-His), it is distinct from other biochemically characterized CEs. CONCLUSIONS: The bifunctional CE, BD-FAE, represents a new candidate for biomass processing given its capacity to remove ferulic acid and acetic acid from natural corn and birchwood xylan substrates, respectively. Its detailed biochemical characterization and solved crystal structure add to the toolbox of enzymes for biomass valorization as well as structural information to inform the classification of new CEs.
Enzymes are usually characterized by their evolutionarily conserved catalytic domains; however, this work presents the incidental gain-of-function of an enzyme in a loop region by natural evolution of its amino acids. A bifunctional acetyl ester-xyloside hydrolase (CLH10) was heterologously expressed, purified, and characterized. The primary sequence of CLH10 contains the fragments of the conserved sequence of esterase and glycosidase, which distribute in a mixed type. The crystal structure revealed that the primary sequence folded into two independent structural regions to undertake both acetyl esterase and beta-1,4-xylanase hydrolase functions. CLH10 is capable of cleaving both the beta-1,4-xylosidic bond-linked main chain and the ester bond-linked acetylated side chain of xylan, which renders it valuable because it can degrade acetylated xylan within one enzyme. Significantly, the beta-1,4-xylanase activity of CLH10 appears to have been fortuitously obtained because of the variable Asp10 and Glu139 located in its loop region, which suggested that the exposed loop region might act as a potential hot-spot for the design and generation of promising enzyme function in both directed evolution and rational protein design.
The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5 degrees C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65 degrees C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16 degrees C, was shown to contain halopiezophilic-like enzymes that are most active at 70 degrees C and with denaturing temperatures of 71.4 degrees C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes.
Lactobacillus plantarum is the lactic acid bacterial species most frequently found in the fermentation of food products of plant origin on which phenolic compounds are abundant. L. plantarum strains showed great flexibility in their ability to adapt to different environments and growth substrates. Of 28 L. plantarum strains analyzed, only cultures from 7 strains were able to hydrolyze hydroxycinnamic esters, such as methyl ferulate or methyl caffeate. As revealed by PCR, only these seven strains possessed the est_1092 gene. When the est_1092 gene was introduced into L. plantarum WCFS1 or L. lactis MG1363, their cultures acquired the ability to degrade hydroxycinnamic esters. These results support the suggestion that Est_1092 is the enzyme responsible for the degradation of hydroxycinnamic esters on the L. plantarum strains analyzed. The Est_1092 protein was recombinantly produced and biochemically characterized. Surprisingly, Est_1092 was able to hydrolyze not only hydroxycinnamic esters, since all the phenolic esters assayed were hydrolyzed. Quantitative PCR experiments revealed that the expression of est_1092 was induced in the presence of methyl ferulate, an hydroxycinnamic ester, but was inhibited on methyl gallate, an hydroxybenzoic ester. As Est_1092 is an enzyme active on a broad range of phenolic esters, simultaneously possessing feruloyl esterase and tannase activities, its presence on some L. plantarum strains provides them with additional advantages to survive and grow on plant environments.
Title: The Structure of a Novel Thermophilic Esterase from the Planctomycetes Species, Reveals an Open Active Site Due to a Minimal 'Cap' Domain Sayer C, Szabo Z, Isupov MN, Ingham C, Littlechild JA Ref: Front Microbiol, 6:1294, 2015 : PubMed
A carboxyl esterase (TtEst2) has been identified in a novel thermophilic bacterium, Thermogutta terrifontis from the phylum Planctomycetes and has been cloned and over-expressed in Escherichia coli. The enzyme has been characterized biochemically and shown to have activity toward small p-nitrophenyl (pNP) carboxylic esters with optimal activity for pNP-acetate. The enzyme shows moderate thermostability retaining 75% activity after incubation for 30 min at 70 degrees C. The crystal structures have been determined for the native TtEst2 and its complexes with the carboxylic acid products propionate, butyrate, and valerate. TtEst2 differs from most enzymes of the alpha/beta-hydrolase family 3 as it lacks the majority of the 'cap' domain and its active site cavity is exposed to the solvent. The bound ligands have allowed the identification of the carboxyl pocket in the enzyme active site. Comparison of TtEst2 with structurally related enzymes has given insight into how differences in their substrate preference can be rationalized based upon the properties of their active site pockets.
The hydrolase fold is one of the most versatile structures in the protein realm according to the diversity of sequences adopting such a three-dimensional architecture. In the present study, we clarified the crystal structure of the carboxylesterase Cest-2923 from the lactic acid bacterium Lactobacillus plantarum WCFS1 refined to 2.1 A resolution, determined its main biochemical characteristics and also carried out an analysis of its associative behaviour in solution. We found that the versatility of a canonical alpha/beta hydrolase fold, the basic framework of the crystal structure of Cest-2923, also extends to its oligomeric behaviour in solution. Thus, we discovered that Cest-2923 exhibits a pH-dependent pleomorphic behaviour in solution involving monomers, canonical dimers and tetramers. Although, at neutral pH, the system is mainly shifted to dimeric species, under acidic conditions, tetrameric species predominate. Despite these tetramers resulting from the association of canonical dimers, as is commonly found in many other carboxylesterases from the hormone-sensitive lipase family, they can be defined as 'noncanonical' because they represent a different association mode. We identified this same type of tetramer in the closest relative of Cest-2923 that has been structurally characterized: the sugar hydrolase YeeB from Lactococcus lactis. The observed associative behaviour is consistent with the different crystallographic results for Cest-2923 from structural genomics consortia. Finally, the presence of sulfate or acetate molecules (depending on the crystal form analysed) in the close vicinity of the nucleophile Ser116 allows us to identify interactions with the putative oxyanion hole and deduce the existence of hydrolytic activity within Cest-2923 crystals. STRUCTURED DIGITAL ABSTRACT: Cest-2923 and Cest-2923 bind by x-ray crystallography (1, 2) Cest-2923 and Cest-2923 bind by cosedimentation in solution (1, 2) DATABASE: The atomic coordinates and structure factors have been deposited in the Protein Data Bank with accession numbers: 4BZW for Cest-2923 from native crystals not soaked with substrates (P63 22 space group); 4C01 for Cest-2923 from crystals soaked with phenyl acetate (C2 space group); 4BZZ for Cest-2923 from crystals soaked with isopropenyl acetate (P622 space group).
Bacterial esterases. Fang et al. described a novel esterase from a marine metagenomic library exhibiting high salt tolerance. The enzyme is essentially active on pNP-C2 C4 and C6. The family is extracted from 6_AlphaBeta_hydrolase. This family differs from all the families of the Arpigny Jaeger classification.
Title: Characterization of a novel hyper-thermostable and chlorpyrifos-hydrolyzing carboxylesterase EstC: A representative of the new esterase family XIX Wang B, Wu S, Chang X, Chen J, Ma J, Wang P, Zhu G Ref: Pestic Biochem Physiol, 170:104704, 2020 : PubMed
Carboxylesterases have widely been used in a series of industrial applications, especially, the detoxification of pesticide residues. In the present study, EstC, a novel carboxylesterase from Streptomyces lividans TK24, was successfully heterogeneously expressed, purified and characterized. Phylogenetic analysis showed that EstC can be assigned as the first member of a novel family XIX. Multiple sequence alignment indicated that EstC has highly conserved structural features, including a catalytic triad formed by Ser155, Asp248 and His278, as well as a canonical Gly-His-Ser-Ala-Gly pentapeptide. Biochemical characterization indicated that EstC exhibited maximal activity at pH 9.0 (Tris-HCl buffer) and 55 degC. It also showed higher activity towards short-chain substrates, with the highest activity for p-nitrophenyl acetate (pNPA2) (K(m) = 0.31 +/- 0.02 mM, k(cat)/K(m) = 1923.35 +/- 9.62 s(-1) mM(-1)) compared to other pNP esters used in this experiment. Notably, EstC showed hyper-thermostability and good alkali stability. The activity of EstC had no significant changes when it was incubated under 55 degC for 100 h and reached half-life after incubation at 100 degC for 8 h. Beyond that, EstC also showed stability at pH ranging from 6.0 to 11.0 and about 90% residual activity still reserved after treatment at pH 8.0 or 9.0 for 26 h, especially. Furthermore, EstC had outstanding potential for bioremediation of chlorpyrifos-contaminated environment. The recombinant enzyme (0.5 U mL(-1)) could hydrolyze 79.89% chlorpyrifos (5 mg L(-1)) at 37 degC within 80 min. These properties will make EstC have a potential application value in various industrial productions and detoxification of chlorpyrifos residues.
Title: A novel esterase from a marine metagenomic library exhibiting salt tolerance ability Fang Z, Li J, Wang Q, Fang W, Peng H, Zhang X, Xiao Y Ref: J Microbiol Biotechnol, 24:771, 2014 : PubMed
A putative lipolytic enzyme gene, named as est9x, was obtained from a marine microbial metagenome of the South China Sea. Sequence analysis showed that Est9X shares lower than 27% sequence identities with the characterized lipolytic enzymes, but possesses a catalytic triad highly conserved in lipolytic enzymes of the alpha/beta hydrolase superfamily. By phylogenetic tree construction, Est9X was grouped into a new lipase/esterase family. To understand Est9X protein in depth, it was recombinantly expressed, purified, and biochemically characterized. Within potential hydrolytic activities, only lipase/esterase activity was detected for Est9X, confirming its identity as a lipolytic enzyme. When using p-nitrophenol esters with varying lengths of fatty acid as substrates, Est9X exhibited the highest activity to the C2 substrate, indicating it is an esterase. The optimal activity of Est9X occurred at a temperature of 65 degrees C, and Est9X was pretty stable below the optimum temperature. Distinguished from other salttolerant esterases, Est9X's activity was tolerant to and even promoted by as high as 4 M NaCl. Our results imply that Est9X is a unique esterase and could be a potential candidate for industrial application under extreme conditions.
Sequences of lipases from metagenomic library were grouped in a new subset of Alphabeta hydrolase fold-3 (Arpigny_Jaeger Family_IV). Most sequences have a G(TDC)SA(G)G motif encompassing the active site serine.
Lipases comprise a large class of hydrolytic enzymes which catalyze the cleavage of the ester bonds in triacylglycerols and find numerous biotechnological applications. Previously, we have cloned the gene coding for a novel esterase PMGL2 from a Siberian permafrost metagenomic DNA library. We have determined the 3D structure of PMGL2 which belongs to the hormone-sensitive lipase (HSL) family and contains a new variant of the active site motif, GCSAG. Similar to many other HSLs, PMGL2 forms dimers in solution and in the crystal. Our results demonstrated that PMGL2 and structurally characterized members of the GTSAG motif subfamily possess a common dimerization interface that significantly differs from that of members of the GDSAG subfamily of known structure. Moreover, PMGL2 had a unique organization of the active site cavity with significantly different topology compared to the other lipolytic enzymes from the HSL family with known structure including the distinct orientation of the active site entrances within the dimer and about four times larger size of the active site cavity. To study the role of the cysteine residue in GCSAG motif of PMGL2, the catalytic properties and structure of its double C173T/C202S mutant were examined and found to be very similar to the wild type protein. The presence of the bound PEG molecule in the active site of the mutant form allowed for precise mapping of the amino acid residues forming the substrate cavity.
As a result of construction and screening of a metagenomic library prepared from a permafrost-derived microcosm, we have isolated a novel gene coding for a putative lipolytic enzyme that belongs to the hormone-sensitive lipase family. It encodes a polypeptide of 343 amino acid residues whose amino acid sequence displays maximum likelihood with uncharacterized proteins fromSphingomonasspecies. A putative catalytic serine residue of PMGL2 resides in a new variant of a recently discovered GTSAG sequence in which a Thr residue is replaced by a Cys residue (GCSAG). The recombinant PMGL2 was produced inEscherichia colicells and purified by Ni-affinity chromatography. The resulting protein preferably utilizes short-chainp-nitrophenyl esters (C4 and C8) and therefore is an esterase. It possesses maximum activity at 45 degrees C in slightly alkaline conditions and has limited thermostability at higher temperatures. Activity of PMGL2 is stimulated in the presence of 0.25-1.5 M NaCl indicating the good salt tolerance of the new enzyme. Mass spectrometric analysis demonstrated that N-terminal methionine in PMGL2 is processed and cysteine residues do not form a disulfide bond. The results of the study demonstrate the significance of the permafrost environment as a unique genetic reservoir and its potential for metagenomic exploration.
The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5 degrees C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65 degrees C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in salt-saturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deep-sea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16 degrees C, was shown to contain halopiezophilic-like enzymes that are most active at 70 degrees C and with denaturing temperatures of 71.4 degrees C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes.
Hormone-sensitive lipases (HSLs) are widely distributed in microorganisms, plants, and animals. Microbial HSLs are classified into two subfamilies, an unnamed new subfamily and the GDSAG motif subfamily. Due to the lack of structural information, the detailed catalytic mechanism of the new subfamily is not yet clarified. Based on sequence analysis, we propose to name the new subfamily as the GTSAG motif subfamily. We identified a novel HSL esterase E25, a member of the GTSAG motif subfamily, by functional metagenomic screening, and resolved its structure at 2.05 A. E25 is mesophilic (optimum temperature at 50 degrees C), salt-tolerant, slightly alkaline (optimum pH at 8.5) for its activity, and capable of hydrolyzing short chain monoesters (C2-C10). E25 tends to form dimers both in the crystal and in solution. An E25 monomer contains an N-terminal CAP domain, and a classical alpha/beta hydrolase-fold domain. Residues Ser186, Asp282, and His312 comprise the catalytic triad. Structural and mutational analyses indicated that E25 adopts a dimerization pattern distinct from other HSLs. E25 dimer is mainly stabilized by an N-terminal loop intersection from the CAP domains and hydrogen bonds and salt bridges involving seven highly conserved hydrophilic residues from the catalytic domains. Further analysis indicated that E25 also has some catalytic profiles different from other HSLs. Dimerization is essential for E25 to exert its catalytic activity by keeping the accurate orientation of the catalytic Asp282 within the catalytic triad. Our results reveal the structural basis for dimerization and catalysis of an esterase from the GTSAG motif subfamily of the HSL family.
Title: Identification of a new subfamily of salt-tolerant esterases from a metagenomic library of tidal flat sediment Jeon JH, Lee HS, Kim JT, Kim SJ, Choi SH, Kang SG, Lee JH Ref: Applied Microbiology & Biotechnology, 93:623, 2012 : PubMed
To search for novel lipolytic enzymes, a metagenomic library was constructed from the tidal flat sediment of Ganghwa Island in South Korea. By functional screening using tributyrin agar plates, 3 clones were selected from among the 80,050 clones of the fosmid library. The sequence analysis revealed that those clones contained different open reading frames, which showed 50-57% amino acid identity with putative lipolytic enzymes in the database. Based on the phylogenetic analysis, they were identified to encode novel members, which form a distinct and new subfamily in the family IV of bacterial lipolytic enzymes. The consensus sequence, GT(S)SA(G)G, encompassing the active site serine of the enzymes was different from the GDSAG motif, conserved in the other subfamily. The genes were expressed in Escherichia coli and recombinant proteins were purified as active soluble forms. The enzymes showed the highest activity toward p-nitrophenyl valerate (C5) and exhibited optimum activities at mesophilic temperature ranges and slightly alkaline pH. In particular, the enzymes displayed salt tolerance with over 50% of the maximum activity remained in the presence of 3 M NaCl (or KCl). In this study, we demonstrated that the metagenomic approach using marine tidal flat sediment as a DNA source expanded the diversity of lipolytic enzyme-encoding genes.
Sequence similarities between hormone-sensitive lipase and prokaryotic enzymes was dicovered by Langin and Holm and Hemila et al.. The family Corresponds to the Pfam entry Abhydrolase_3. For bacterial enzymes this family correspond to family IV of the classification of Arpigny et al 1999
Title: An overview of mammalian and microbial hormone-sensitive lipases (lipolytic family IV): biochemical properties and industrial applications Nagaroor V, Gummadi SN Ref: Biotechnol Genet Eng Rev, :1, 2022 : PubMed
In mammals, hormone-sensitive lipase (EC 3.1.1.79) is an intracellular lipase that significantly regulates lipid metabolism. Mammalian HSL is more active towards diacylglycerol but lacks a lid covering the active site. Dyslipidemia, hepatic steatosis, cancer, and cancer-associated cachexia are symptoms of HSL pathophysiology. Certain microbial proteins show a sequence homologous to the catalytic domain of mammalian HSL, hence called microbial HSL. They possess a funnel-shaped substrate-binding pocket and restricted length of acyl chain esters, thus known as esterases. These enzymes have broad substrate specificities and are capable of stereo, regio, and enantioselective, making them attractive biocatalysts in a wide range of industrial applications in the production of flavors, pharmaceuticals, biosensors, and fine chemicals. This review will provide insight into mammalian and microbial HSLs, their sources, structural features related to substrate specificity, thermal stability, and their applications.
Hormone-sensitive lipase (HSL) was initially characterized as the hormonally regulated neutral lipase activity responsible for the breakdown of triacylglycerols into fatty acids in adipose tissue. This review aims at providing up-to-date information on structural properties, regulation of expression, activity and function as well as therapeutic potential. The lipase is expressed as different isoforms produced from tissue-specific alternative promoters. All isoforms are composed of an N-terminal domain and a C-terminal catalytic domain within which a regulatory domain containing the phosphorylation sites is embedded. Some isoforms possess additional N-terminal regions. The catalytic domain shares similarities with bacteria, fungus and plant proteins but not with other mammalian lipases. HSL singularity is provided by regulatory and N-terminal domains sharing no homology with other proteins. HSL has a large substrate specificity compared to other neutral lipases. It hydrolyzes acylglycerols, cholesteryl and retinyl esters among other substrates. A novel role of HSL, independent of its enzymatic function, has recently been described in adipocytes. Clinical studies revealed dysregulations of HSL expression and activity in disorders, such as lipodystrophy, obesity, type 2 diabetes and cancer-associated cachexia. Development of specific inhibitors positions HSL as a pharmacological target for the treatment of metabolic complications.
Title: Bacterial Hormone-Sensitive Lipases (bHSLs): Emerging Enzymes for Biotechnological Applications Kim TD Ref: J Microbiol Biotechnol, 27:1907, 2017 : PubMed
Lipases are important enzymes with biotechnological applications in dairy, detergent, food, fine chemicals, and pharmaceutical industries. Specifically, hormone-sensitive lipase (HSL) is an intracellular lipase that can be stimulated by several hormones, such as catecholamine, glucagon, and adrenocorticotropic hormone. Bacterial hormone-sensitive lipases (bHSLs), which are homologous to the C-terminal domain of HSL, have alpha/beta-hydrolase fold with a catalytic triad composed of His, Asp, and Ser. These bHSLs could be used for a wide variety of industrial applications because of their high activity, broad substrate specificity, and remarkable stability. In this review, the relationships among HSLs, the microbiological origins, the crystal structures, and the biotechnological properties of bHSLs are summarized.
Fatty liver is a major health problem worldwide. People with hereditary deficiency of hormone-sensitive lipase (HSL) are reported to develop fatty liver. In this study, systemic and tissue-specific HSL-deficient mice were used as models to explore the underlying mechanism of this association. We found that systemic HSL deficient mice developed fatty liver in an age-dependent fashion between 3 and 8 months of age. To further explore the mechanism of fatty liver in HSL deficiency, liver-specific HSL knockout mice were created. Surprisingly, liver HSL deficiency did not influence liver fat content, suggesting that fatty liver in HSL deficiency is not liver autonomous. Given the importance of adipose tissue in systemic triglyceride metabolism, we created adipose-specific HSL knockout mice and found that adipose HSL deficiency, to a similar extent as systemic HSL deficiency, causes age-dependent fatty liver in mice. Mechanistic study revealed that deficiency of HSL in adipose tissue caused inflammatory macrophage infiltrates, progressive lipodystrophy, abnormal adipokine secretion and systemic insulin resistance. These changes in adipose tissue were associated with a constellation of changes in liver: low levels of fatty acid oxidation, of very low density lipoprotein secretion and of triglyceride hydrolase activity, each favoring the development of hepatic steatosis. In conclusion, HSL-deficient mice revealed a complex interorgan interaction between adipose tissue and liver: the role of HSL in the liver is minimal but adipose tissue deficiency of HSL can cause age-dependent hepatic steatosis. Adipose tissue is a potential target for treating the hepatic steatosis of HSL deficiency.
Title: Molecular cloning and characterization of a thermostable carboxylesterase from an archaeon, Sulfolobus shibatae DSM5389: non-linear kinetic behavior of a hormone-sensitive lipase family enzyme Ejima K, Liu J, Oshima Y, Hirooka K, Shimanuki S, Yokota Y, Hemmi H, Nakayama T, Nishino T Ref: J Biosci Bioeng, 98:445, 2004 : PubMed
A gene coding for an esterase (SshEstI, 915 bp in length) of the thermoacidophilic archaeon Sulfolobus shibatae DSM5389 was cloned, sequenced, and overexpressed in Escherichia coli JM109 cells as a soluble, catalytically active protein. The deduced amino acid sequence of SshEstI was consistent with a protein containing 305 amino acid residues with a molecular mass of 33 kDa. Sequence comparison studies indicated that SshEstI could be a member of the hormone-sensitive lipase family, in that it had the highest sequence similarity to esterases from Sulfolobus solfataricus (90% identity) and Archaeoglobus fulgidus (42%) and a lipase from Pseudomonas sp. B11-1 (38%). The recombinant enzyme was highly thermostable and retained more than 70% of its initial activity after incubation at 90 degrees C and pH 7.0 for 30 min. The recombinant enzyme catalyzed the hydrolysis of p-nitrophenyl (p-NP) esters with C2-C16 acyl chains but not the hydrolysis of triacylglycerides such as tributyrin and triolein. The enzymatic hydrolysis of p-NP acetate proceeded in a linear manner with time, whereas that of p-NP esters with acyl chains of C5 or longer showed a biphasic profile, where a rapid release of p-nitrophenol ( approximately 3 min) was followed by a slow, sustained release. These non-linear kinetics may be explained in terms of a very slow, presteady-state burst phenomenon of p-nitrophenol release or a hysteretic behavior of SshEstI with these substrates.
Title: Structure-function relationships of hormone-sensitive lipase Osterlund T Ref: European Journal of Biochemistry, 268:1899, 2001 : PubMed
Research into the structure-function relationships of lipases and esterases has increased significantly during the past decade. Of particular importance has been the deduction of several crystal structures, providing a new basis for understanding these enzymes. The generated insights have, together with cloning and expression, aided studies on structure-function relationships of hormone-sensitive lipase (HSL). Novel phosphorylation sites have been identified in HSL, which are probably important for activation of HSL and lipolysis. Functional and structural analyses have revealed features in HSL common to lipases and esterases. In particular, the catalytic core with a catalytic triad has been unveiled. Furthermore, the investigations have given clear suggestions with regard to the identity of functional and structural domains of HSL. In the present paper, these studies on HSL structure-function relationships and short-term regulation are reviewed, and the results presented in relation to other discoveries in regulated lipolysis.
Hormone-sensitive lipase, the rate-limiting enzyme of intracellular TG hydrolysis, is a major determinant of fatty acid mobilization in adipose tissue as well as other tissues. It plays a pivotal role in lipid metabolism, overall energy homeostasis, and, presumably, cellular events involving fatty acid signaling. Detailed knowledge about its structure and regulation may provide information regarding the pathogenesis of such human diseases as obesity and diabetes and may generate concepts for new treatments of these diseases. The current review summarizes the recent advances with regard to hormone-sensitive lipase structure and molecular mechanisms involved in regulating its activity and lipolysis in general. A summary of the current knowledge regarding regulation of expression, potential involvement in lipid disorders, and role in tissues other than adipose tissue is also provided.
Title: Hormone-sensitive lipase is closely related to several bacterial proteins, and distantly related to acetylcholinesterase and lipoprotein lipase: identification of a superfamily of esterases and lipases Hemila H, Koivula TT, Palva I Ref: Biochimica & Biophysica Acta, 1210:249, 1994 : PubMed
We have sequenced a gene from Bacillus acidocaldarius which encodes an open reading frame (ORF3) of 310 amino acids. The ORF3 was found to be related to the mammalian hormone-sensitive lipase (HSL). Searching the protein data base revealed five other bacterial proteins related to the HSL. Upon further sequence comparisons this HSL-group was found to be related to the family of carboxylesterases, and to a family of lipases (lipoprotein, hepatic and pancreatic lipases). The evolutionary relationship of these serine-dependent hydrolytic enzymes has not been studied previously, and it has not been known that these proteins belong to the same superfamily. Finally, the alignment of the HSL with the bacterial proteins allowed us to infer the location of the hormone-sensitive regulatory domain of the HSL-protein.
Title: Sequence similarities between hormone-sensitive lipase and five prokaryotic enzymes Langin D, Holm C Ref: Trends in Biochemical Sciences, 18:466, 1993 : PubMed
Kynurenine formamidase (EC:3.5.1.9) catalyses the hydrolysis of N-formyl-L-kynurenine to L-kynurenine, the second step in the kynurenine pathway of tryptophan degradation. It is required for elimination of toxic metabolites
Title: Biochemical identification and crystal structure of kynurenine formamidase from Drosophila melanogaster. Han Q, Robinson H, Li J Ref: Biochemical Journal, 446:253, 2012 : PubMed
KFase (kynurenine formamidase), also known as arylformamidase and formylkynurenine formamidase, efficiently catalyses the hydrolysis of NFK (N-formyl-L-kynurenine) to kynurenine. KFase is the second enzyme in the kynurenine pathway of tryptophan metabolism. A number of intermediates formed in the kynurenine pathway are biologically active and implicated in an assortment of medical conditions, including cancer, schizophrenia and neurodegenerative diseases. Consequently, enzymes involved in the kynurenine pathway have been considered potential regulatory targets. In the present study, we report, for the first time, the biochemical characterization and crystal structures of Drosophila melanogaster KFase conjugated with an inhibitor, PMSF. The protein architecture of KFase reveals that it belongs to the alpha/beta hydrolase fold family. The PMSF-binding information of the solved conjugated crystal structure was used to obtain a KFase and NFK complex using molecular docking. The complex is useful for understanding the catalytic mechanism of KFase. The present study provides a molecular basis for future efforts in maintaining or regulating kynurenine metabolism through the molecular and biochemical regulation of KFase.
Title: Identification of formyl kynurenine formamidase and kynurenine aminotransferase from Saccharomyces cerevisiae using crystallographic, bioinformatic and biochemical evidence Wogulis M, Chew ER, Donohoue PD, Wilson DK Ref: Biochemistry, 47:1608, 2008 : PubMed
The essential enzymatic cofactor NAD+ can be synthesized in many eukaryotes, including Saccharomyces cerevisiae and mammals, using tryptophan as a starting material. Metabolites along the pathway or on branches have important biological functions. For example, kynurenic acid can act as an NMDA antagonist, thereby functioning as a neuroprotectant in a wide range of pathological states. N-Formyl kynurenine formamidase (FKF) catalyzes the second step of the NAD+ biosynthetic pathway by hydrolyzing N-formyl kynurenine to produce kynurenine and formate. The S. cerevisiae FKF had been reported to be a pyridoxal phosphate-dependent enzyme encoded by BNA3. We used combined crystallographic, bioinformatic and biochemical methods to demonstrate that Bna3p is not an FKF but rather is most likely the yeast kynurenine aminotransferase, which converts kynurenine to kynurenic acid. Additionally, we identify YDR428C, a yeast ORF coding for an alpha/beta hydrolase with no previously assigned function, as the FKF. We predicted its function based on our interpretation of prior structural genomics results and on its sequence homology to known FKFs. Biochemical, bioinformatics, genetic and in vivo metabolite data derived from LC-MS demonstrate that YDR428C, which we have designated BNA7, is the yeast FKF.
The molecular weight forms of kynurenine formamidase were studied both gentically and biochemically. Formamidase I (native molecular weight 60,000) was purified using (NH4)2SO4 and pH fractionation, DEAE-cellulose chromatography at two different pH's, hydroxylapatite chromatography, and Sephadex G-100 gel filtration. Its subunit molecular weight, as determined by SDS gel electrophoresis, is 34,000, indicating that formamidase I is a dimer. Its Km is 1.87 X 10(-3) M. Its isoelectric point is pH 5.3. Its amino acid composition is reported. Formamidase II (native molecular weight 31,000) was partially purified using techniques similar to those above. Its Km is 2.31 X 10(-3) M. The response of formamidase activity to change in gene dosage was measured in segmental aneuploids generated in the second, third, and X chromosomes. Two separate chromosomal regions were identified which when present in extra dosage result in an elevation of the level of formamidase activity close to that predicted for the addition of a structural gene in a two-gene system. These tentative map positions were substantiated by demonstration that addition of one of the regions, 25A-27E, causes a 50% elevation in the relative amount of formamidase II. Addition of the other region, 91B-93F, causes a similar elevation in the relative amount of formamidase I. A model of the evolutionary origin of the two forms is presented, and the significance of these results to this model is discussed.
No plant Carboxylesterase show the SEDCLYLN motif (prosite PS00941). These carboxylesterase are related to the Hormone sensitive lipase. Gibbereline Insensitive Dwarf1 GID1 has a primary structure similar to that of the hormone-sensitive lipase. Gibberellins (GAs) are tetracyclic, diterpenoid plant hormones, essential for many developmental processes in higher plants HSLs. The nuclear GA receptor evolved from an esterase. 2-hydroxyisoflavone dehydratase from leguminosae also belong to this family, in these particular enzymes the catalytic serine is replaced by threonine. In tulips tuliposide-converting enzyme (TCE) purified from tulip bulbs catalyzed the conversion of tuliposides to tulipalins.The lactone-forming carboxylesterases, specifically catalyzing intramolecular transesterification, but not hydrolysis
BACKGROUND: Carboxylesterase (CXE) is a type of hydrolase with alpha/beta sheet hydrolase activity widely found in animals, plants and microorganisms, which plays an important role in plant growth, development and resistance to stress. RESULTS: A total of 72, 74, 39, 38 CXE genes were identified in Gossypium barbadense, Gossypium hirsutum, Gossypium raimondii and Gossypium arboreum, respectively. The gene structure and expression pattern were analyzed. The GBCXE genes were divided into 6 subgroups, and the chromosome distribution of members of the family were mapped. Analysis of promoter cis-acting elements showed that most GBCXE genes contain cis-elements related to plant hormones (GA, IAA) or abiotic stress. These 6 genes we screened out were expressed in the root, stem and leaf tissues. Combined with the heat map, GBCXE49 gene was selected for subcellular locate and confirmed that the protein was expressed in the cytoplasm. CONCLUSIONS: The collinearity analysis of the CXE genes of the four cotton species in this family indicated that tandem replication played an indispensable role in the evolution of the CXE gene family. The expression patterns of GBCXE gene under different stress treatments indicated that GBCXE gene may significantly participate in the response to salt and alkaline stress through different mechanisms. Through the virus-induced gene silencing technology (VIGS), it was speculated that GBCXE49 gene was involved in the response to alkaline stress in G. barbadense.
The plant gibberellin (GA) receptor GID1 shows sequence similarity to carboxylesterase (CXE). Here, we report the molecular evolution of GID1 from establishment to functionally diverse forms in eudicots. By introducing 18 mutagenized rice GID1s into a rice gid1 null mutant, we identified the amino acids crucial for GID1 activity in planta. We focused on two amino acids facing the C2/C3 positions of ent-gibberellane, not shared by lycophytes and euphyllophytes, and found that adjustment of these residues resulted in increased GID1 affinity toward GA4, new acceptance of GA1 and GA3 carrying C13-OH as bioactive ligands, and elimination of inactive GAs. These residues rendered the GA perception system more sophisticated. We conducted phylogenetic analysis of 169 GID1s from 66 plant species and found that, unlike other taxa, nearly all eudicots contain two types of GID1, named A- and B-type. Certain B-type GID1s showed a unique evolutionary characteristic of significantly higher nonsynonymous-to-synonymous divergence in the region determining GA4 affinity. Furthermore, these B-type GID1s were preferentially expressed in the roots of Arabidopsis, soybean, and lettuce and might be involved in root elongation without shoot elongation for adaptive growth under low-temperature stress. Based on these observations, we discuss the establishment and adaption of GID1s during plant evolution.
Title: Molecular identification of tuliposide B-converting enzyme: a lactone-forming carboxylesterase from the pollen of tulip Nomura T, Murase T, Ogita S, Kato Y Ref: Plant J, 83:252, 2015 : PubMed
6-Tuliposides A (PosA) and B (PosB), which are the major secondary metabolites in tulip (Tulipa gesneriana), are enzymatically converted to the antimicrobial lactonized aglycons, tulipalins A (PaA) and B (PaB), respectively. We recently identified a PosA-converting enzyme (TCEA) as the first reported member of the lactone-forming carboxylesterases. Herein, we describe the identification of another lactone-forming carboxylesterase, PosB-converting enzyme (TCEB), which preferentially reacts with PosB to give PaB. This enzyme was isolated from tulip pollen, which showed high PosB-converting activity. Purified TCEB exhibited greater activity towards PosB than PosA, which was contrary to that of the TCEA. Novel cDNA (TgTCEB1) encoding the TCEB was isolated from tulip pollen. TgTCEB1 belonged to the carboxylesterase family and was approximately 50% identical to the TgTCEA polypeptides. Functional characterization of the recombinant enzyme verified that TgTCEB1 catalyzed the conversion of PosB to PaB with an activity comparable with the native TCEB. RT-qPCR analysis of each part of plant revealed that TgTCEB1 transcripts were limited almost exclusively to the pollen. Furthermore, the immunostaining of the anther cross-section using anti-TgTCEB1 polyclonal antibody verified that TgTCEB1 was specifically expressed in the pollen grains, but not in the anther cells. N-terminal transit peptide of TgTCEB1 was shown to function as plastid-targeted signal. Taken together, these results indicate that mature TgTCEB1 is specifically localized in plastids of pollen grains. Interestingly, PosB, the substrate of TgTCEB1, accumulated on the pollen surface, but not in the intracellular spaces of pollen grains.
Title: Molecular diversity of tuliposide A-converting enzyme in the tulip Nomura T, Tsuchigami A, Ogita S, Kato Y Ref: Biosci Biotechnol Biochem, 77:1042, 2013 : PubMed
Tuliposide A-converting enzyme (TCEA) catalyzes the conversion of 6-tuliposide A to its lactonized aglycon, tulipalin A, in the tulip (Tulipa gesneriana). The TgTCEA gene, isolated previously from petals, was transcribed in all tulip tissues but not in the bulbs despite the presence of TCEA activity, which allowed prediction of the presence of a TgTCEA isozyme gene preferentially expressed in the bulbs. Here, the TgTCEA-b gene, the TgTCEA homolog, was identified in bulbs. TgTCEA-b polypeptides showed approximately 77% identity to the petal TgTCEA. Functional characterization of the recombinant enzyme verified that TgTCEA-b encoded the TCEA. Moreover, the TgTCEA-b was found to be localized to plastids, as found for the petal TgTCEA. Transcript analysis revealed that TgTCEA-b was functionally transcribed in the bulb scales, unlike the TgTCEA gene, whose transcripts were absent there. In contrast, TgTCEA-b transcripts were in the minority in other tissues where TgTCEA transcripts were dominant, indicating a tissue preference for the transcription of those isozyme genes.
Title: Molecular determinants that convert hormone sensitive lipase into gibberellin receptor Hirano K, Aya K, Matsuoka M, Ueguchi-Tanaka M Ref: Protein Pept Lett, 19:180, 2012 : PubMed
Gibberellins (GAs) are tetracyclic, diterpenoid plant hormones, essential for many developmental processes in higher plants. Plants perceive GA through a nuclear-localized GA receptor, GA INSENSITIVE DWARF1 (GID1). From sequence similarity, it is suggested that GID1 evolved from a hormone-sensitive lipase (HSL), and recent x-ray crystallography of the GA-GID1 complex has given insights into how GID1 recognizes GA. Analyses of the GA signaling pathway in several plant species further suggest that the GID1-mediated GA signaling pathway emerged in the vascular plant lineage and since then regulation of GA recognition specificity seems to have been fine tuned to strictly regulate the on-off GA signal.
Title: A novel lactone-forming carboxylesterase: molecular identification of a tuliposide A-converting enzyme in tulip Nomura T, Ogita S, Kato Y Ref: Plant Physiol, 159:565, 2012 : PubMed
Tuliposides, the glucose esters of 4-hydroxy-2-methylenebutanoate and 3,4-dihydroxy-2-methylenebutanoate, are major secondary metabolites in tulip (Tulipa gesneriana). Their lactonized aglycons, tulipalins, function as defensive chemicals due to their biological activities. We recently found that tuliposide-converting enzyme (TCE) purified from tulip bulbs catalyzed the conversion of tuliposides to tulipalins, but the possibility of the presence of several TCE isozymes was raised: TCE in tissues other than bulbs is different from bulb TCE. Here, to prove this hypothesis, TCE was purified from petals, which have the second highest TCE activity after bulbs. The purified enzyme, like the bulb enzyme, preferentially accepted tuliposides as substrates, with 6-tuliposide A the best substrate, which allowed naming the enzyme tuliposide A-converting enzyme (TCEA), but specific activity and molecular mass differed between the petal and bulb enzymes. After peptide sequencing, a novel cDNA (TgTCEA) encoding petal TCEA was isolated, and the functional characterization of the recombinant enzyme verified that TgTCEA catalyzes the conversion of 6-tuliposide A to tulipalin A. TgTCEA was transcribed in all tulip tissues but not in bulbs, indicating the presence of a bulb-specific TgTCEA, as suggested by the distinct enzymatic characters between the petal and bulb enzymes. Plastidial localization of TgTCEA enzyme was revealed, which allowed proposing a cytological mechanism of TgTCE-mediated tulipalin formation in the tulip defensive strategy. Site-directed mutagenesis of TgTCEA suggested that the oxyanion hole and catalytic triad characteristic of typical carboxylesterases are essential for the catalytic process of TgTCEA enzyme. To our knowledge, TgTCEA is the first identified member of the lactone-forming carboxylesterases, specifically catalyzing intramolecular transesterification.
Gibberellins control a range of growth and developmental processes in higher plants and have been widely used in the agricultural industry. By binding to a nuclear receptor, GIBBERELLIN INSENSITIVE DWARF1 (GID1), gibberellins regulate gene expression by promoting degradation of the transcriptional regulator DELLA proteins, including GIBBERELLIN INSENSITIVE (GAI). The precise manner in which GID1 discriminates and becomes activated by bioactive gibberellins for specific binding to DELLA proteins remains unclear. Here we present the crystal structure of a ternary complex of Arabidopsis thaliana GID1A, a bioactive gibberellin and the amino-terminal DELLA domain of GAI. In this complex, GID1A occludes gibberellin in a deep binding pocket covered by its N-terminal helical switch region, which in turn interacts with the DELLA domain containing DELLA, VHYNP and LExLE motifs. Our results establish a structural model of a plant hormone receptor that is distinct from the mechanism of the hormone perception and effector recognition of the known auxin receptors.
Gibberellins (GAs) are phytohormones essential for many developmental processes in plants. A nuclear GA receptor, GIBBERELLIN INSENSITIVE DWARF1 (GID1), has a primary structure similar to that of the hormone-sensitive lipases (HSLs). Here we analyse the crystal structure of Oryza sativa GID1 (OsGID1) bound with GA(4) and GA(3) at 1.9 A resolution. The overall structure of both complexes shows an alpha/beta-hydrolase fold similar to that of HSLs except for an amino-terminal lid. The GA-binding pocket corresponds to the substrate-binding site of HSLs. On the basis of the OsGID1 structure, we mutagenized important residues for GA binding and examined their binding activities. Almost all of them showed very little or no activity, confirming that the residues revealed by structural analysis are important for GA binding. The replacement of Ile 133 with Leu or Val-residues corresponding to those of the lycophyte Selaginella moellendorffii GID1s-caused an increase in the binding affinity for GA(34), a 2beta-hydroxylated GA(4). These observations indicate that GID1 originated from HSL and was further modified to have higher affinity and more strict selectivity for bioactive GAs by adapting the amino acids involved in GA binding in the course of plant evolution.
Carboxylesterases (CXEs) are widely distributed in plants, where they have been implicated in roles that include plant defense, plant development, and secondary metabolism. We have cloned, overexpressed, purified, and crystallized a carboxylesterase from the kiwifruit species Actinidia eriantha (AeCXE1). The structure of AeCXE1 was determined by X-ray crystallography at 1.4 A resolution. The crystal structure revealed that AeCXE1 is a member of the alpha/beta-hydrolase fold superfamily, most closely related structurally to the hormone-sensitive lipase subgroup. The active site of the enzyme, located in an 11 A deep hydrophobic gorge, contains the conserved catalytic triad residues Ser169, Asp276, and His306. Kinetic analysis using artificial ester substrates showed that the enzyme can hydrolyze a range of carboxylester substrates with acyl groups ranging from C2 to C16, with a preference for butyryl moieties. This preference was supported by the discovery of a three-carbon acyl adduct bound to the active site Ser169 in the native structure. AeCXE1 was also found to be inhibited by organophosphates, with paraoxon (IC50 = 1.1 muM) a more potent inhibitor than dimethylchlorophosphate (DMCP; IC50 = 9.2 muM). The structure of AeCXE1 with paraoxon bound was determined at 2.3 A resolution and revealed that the inhibitor binds covalently to the catalytic serine residue, with virtually no change in the structure of the enzyme. The structural information for AeCXE1 provides a basis for addressing the wider functional roles of carboxylesterases in plants.
Title: Molecular and biochemical characterization of 2-hydroxyisoflavanone dehydratase. Involvement of carboxylesterase-like proteins in leguminous isoflavone biosynthesis Akashi T, Aoki T, Ayabe S Ref: Plant Physiol, 137:882, 2005 : PubMed
Isoflavonoids are ecophysiologically active secondary metabolites of the Leguminosae and known for health-promoting phytoestrogenic functions. Isoflavones are synthesized by 1,2-elimination of water from 2-hydroxyisoflavanones, the first intermediate with the isoflavonoid skeleton, but details of this dehydration have been unclear. We screened the extracts of repeatedly fractionated Escherichia coli expressing a Glycyrrhiza echinata cDNA library for the activity to convert a radiolabeled precursor into formononetin (7-hydroxy-4'-methoxyisoflavone), and a clone of 2-hydroxyisoflavanone dehydratase (HID) was isolated. Another HID cDNA was cloned from soybean (Glycine max), based on the sequence information in its expressed sequence tag library. Kinetic studies revealed that G. echinata HID is specific to 2,7-dihydroxy-4'-methoxyisoflavanone, while soybean HID has broader specificity to both 4'-hydroxylated and 4'-methoxylated 2-hydroxyisoflavanones, reflecting the structures of isoflavones contained in each plant species. Strikingly, HID proteins were members of a large carboxylesterase family, of which plant proteins form a monophyletic group and some are assigned defensive functions with no intrinsic catalytic activities identified. Site-directed mutagenesis with soybean HID protein suggested that the characteristic oxyanion hole and catalytic triad are essential for the dehydratase as well as the faint esterase activities. The findings, to our knowledge, represent a new example of recruitment of enzymes of primary metabolism during the molecular evolution of plant secondary metabolism.
Carboxylesterases hydrolyze esters of short-chain fatty acids and have roles in animals ranging from signal transduction to xenobiotic detoxification. In plants, however, little is known of their roles. We have systematically mined the genome from the model plant Arabidopsis thaliana for carboxylesterase genes and studied their distribution in the genome and expression profile across a range of tissues. Twenty carboxylesterase genes (AtCXE) were identified. The AtCXE family shares conserved sequence motifs and secondary structure characteristics with carboxylesterases and other members of the larger alpha/beta hydrolase fold superfamily of enzymes. Phylogenetic analysis of the AtCXE genes together with other plant carboxylesterases distinguishes seven distinct clades, with an Arabidopsis thaliana gene represented in six of the seven clades. The AtCXE genes are widely distributed across the genome (present in four of five chromosomes), with the exception of three clusters of tandemly duplicated genes. Of the interchromosomal duplication events, two have been mediated through newly identified partial chromosomal duplication events that also include other genes surrounding the AtCXE loci. Eighteen of the 20 AtCXE genes are expressed over a broad range of tissues, while the remaining 2 (unrelated) genes are expressed only in the flowers and siliques. Finally, hypotheses for the functional roles of the AtCXE family members are presented based on the phylogenetic relationships with other plant carboxylesterases of known function, their expression profile, and knowledge of likely esterase substrates found in plants.
Sterol homeostasis in eukaryotic cells relies on the reciprocal interconversion of free sterols and steryl esters. In Saccharomyces cerevisiae (Baker's yeast) sterol acetylation requires the acetyltransferase Atf2, whereas deacetylation requires Say1, a membrane-anchored deacetylase with a putative active site in the ER lumen. Lack of Say1 results in the secretion of acetylated sterols into the culture medium, indicating that the substrate specificity of Say1 determines whether acetylated sterols are secreted from the cells or whether they are deacetylated and retained. In S. cerevisiae cells lacking Say1 or Atf2 are sensitive against the plant-derived allylbenzene eugenol and both Say1 and Atf2 affect pregnenolone toxicity, indicating that lipid acetylation acts as a detoxification pathway (old DUF2424)
Title: An acetylation/deacetylation cycle controls the export of sterols and steroids from S. cerevisiae Tiwari R, Koffel R, Schneiter R Ref: EMBO Journal, 26:5109, 2007 : PubMed
Sterol homeostasis in eukaryotic cells relies on the reciprocal interconversion of free sterols and steryl esters. Here we report the identification of a novel reversible sterol modification in yeast, the sterol acetylation/deacetylation cycle. Sterol acetylation requires the acetyltransferase ATF2, whereas deacetylation requires SAY1, a membrane-anchored deacetylase with a putative active site in the ER lumen. Lack of SAY1 results in the secretion of acetylated sterols into the culture medium, indicating that the substrate specificity of SAY1 determines whether acetylated sterols are secreted from the cells or whether they are deacetylated and retained. Consistent with this proposition, we find that acetylation and export of the steroid hormone precursor pregnenolone depends on its acetylation by ATF2, but is independent of SAY1-mediated deacetylation. Cells lacking Say1 or Atf2 are sensitive against the plant-derived allylbenzene eugenol and both Say1 and Atf2 affect pregnenolone toxicity, indicating that lipid acetylation acts as a detoxification pathway. The fact that homologues of SAY1 are present in the mammalian genome and functionally substitute for SAY1 in yeast indicates that part of this pathway has been evolutionarily conserved.
This family of bacterial tannases close to hormone sensitive lipases, differs from the (Tannase) tannases and feruloyl esterase of fungi and bacteria grouped in the tannase family. The first structure described by Ren et al.Matoba et al. in this family presents a large cap domain inserted after the beta 7 strand of classical alpha/beta hydrolases. Tannases hydrolyze the galloyl ester bond in tannins to release gallic acid
Tannin acyl hydrolases, also known as tannases, are a group of enzymes critical for the transformation of tannins. The study of these enzymes, which initially evolved in different organisms to detoxify and/or use these plant metabolites, has nowadays become relevant in microbial enzymology research due to their relevant role in food tannin transformation. Microorganisms, particularly bacteria, are major sources of tannase. Cloning and heterologous expression of bacterial tannase genes and structural studies have been performed in the last few years. However, a systematic compilation of the information related to all recombinant tannases, their classification, and characteristics is missing. In this review, we explore the diversity of heterologously produced bacterial tannases, describing their substrate specificity and biochemical characterization. Moreover, a new classification based on sequence similarity analysis is proposed. Finally, putative tannases have been identified in silico for each group of tannases taking advantage of the use of the "tannase" distinctive features previously proposed.
Tannin acylhydrolase (EC 3.1.1.20) referred commonly as tannase catalyzes the hydrolysis of the galloyl ester bond of tannins to release gallic acid. Although the enzyme is useful for various industries, the tertiary structure is not yet determined. In this study, we determined the crystal structure of tannase produced by Lactobacillus plantarum. The tannase structure belongs to a member of alpha/beta-hydrolase superfamily with an additional "lid" domain. A glycerol molecule derived from cryoprotectant solution was accommodated into the tannase active site. The binding manner of glycerol to tannase seems to be similar to that of the galloyl moiety in the substrate. Proteins 2013; 81:2052-2058. (c) 2013 Wiley Periodicals, Inc.
Tannins are water-soluble polyphenolic compounds in plants. Hydrolyzable tannins are derivatives of gallic acid (3,4,5-trihydroxybenzoic acid) or its meta-depsidic forms that are esterified to polyol, catechin, or triterpenoid units. Tannases are a family of esterases that catalyze the hydrolysis of the galloyl ester bond in hydrolyzable tannins to release gallic acid. The enzymes have found wide applications in food, feed, beverage, pharmaceutical, and chemical industries since their discovery more than a century ago, although little is known about them at the molecular level, including the details of the catalytic and substrate binding sites. Here, we report the first three-dimensional structure of a tannase from Lactobacillus plantarum. The enzyme displays an alpha/beta structure, featured by a large cap domain inserted into the classical serine hydrolase fold. A catalytic triad was identified in the structure, which is composed of Ser163, His451, and Asp419. During the binding of gallic acid, the carboxyl group of the molecule forges hydrogen-bonding interactions with the catalytic triad of the enzyme while the three hydroxyl groups make contacts with Asp421, Lys343, and Glu357 to form another hydrogen-bonding network. Mutagenesis studies demonstrated that these residues are indispensable for the activity of the enzyme. Structural studies of the enzyme in complex with a number of substrates indicated that the interactions at the galloyl binding site are the determinant force for the binding of substrates. The single galloyl binding site is responsible for the esterase and depsidase activities of the enzyme.
Structure scheme for Arylacetamide_deacetylase