A gene encoding LgEstI was cloned from a bacterial fish pathogen, Lactococcus garvieae. Sequence and bioinformatic analysis revealed that LgEstI is close to the acetyl esterase family and had maximum similarity to a hydrolase (UniProt: Q5UQ83) from Acanthamoeba polyphaga mimivirus (APMV). Here, we present the results of LgEstI overexpression and purification, and its preliminary X-ray crystallographic analysis. The wild-type LgEstI protein was overexpressed in Escherichia coli, and its enzymatic activity was tested using p-nitrophenyl of varying lengths. LgEstI protein exhibited higher esterase activity toward p-nitrophenyl acetate. To better understand the mechanism underlying LgEstI activity and subject it to protein engineering, we determined the high-resolution crystal structure of LgEstI. First, the wild-type LgEstI protein was crystallized in 0.1 M Tris-HCl buffer (pH 7.1), 0.2 M calcium acetate hydrate, and 19% (w/v) PEG 3000, and the native X-ray diffraction dataset was collected up to 2.0 A resolution. The crystal structure was successfully determined using a molecular replacement method, and structure refinement and model building are underway. The upcoming complete structural information of LgEstI may elucidate the substrate-binding mechanism and provide novel strategies for subjecting LgEstI to protein engineering.
Title: Identification, Characterization, and Preliminary X-ray Diffraction Analysis of a Novel Esterase (ScEst) from Staphylococcus chromogenes Hwang J, Jeon S, Lee M.J, Yoo W, Chang J, Kim KK, Lee JH, Do H, Kim TD Ref: Crystals, 12:546, 2022 : PubMed
Ester prodrugs can develop novel antibiotics and have potential therapeutic applications against multiple drug-resistant bacteria. The antimicrobial activity of these prodrugs is activated after being cleaved by the esterases produced by the pathogen. Here, novel esterase ScEst originating from Staphylococcus chromogenes NCTC10530, which causes dairy cow mastitis, was identified, characterized, and analyzed using X-ray crystallography. The gene encoding ScEst was cloned into the pVFT1S vector and overexpressed in E. coli. The recombinant ScEst protein was obtained by affinity and size-exclusion purification. ScEst showed substrate preference for the short chain length of acyl derivatives. It was crystallized in an optimized solution composed of 0.25 M ammonium citrate tribasic (pH 7.0) and 20% PEG 3350 at 296 K. A total of 360 X-ray diffraction images were collected at a 1.66 A resolution. ScEst crystal belongs to the space group of P212121 with the unit cell parameters of a = 50.23 A, b = 68.69 A, c = 71.15 A, and alpha = beta = gamma = 90deg. Structure refinement after molecular replacement is under progress. Further biochemical studies will elucidate the hydrolysis mechanism of ScEst. Overall, this study is the first to report the functional characterization of an esterase from Staphylococcus chromogenes, which is potentially useful in elaborating its hydrolysis mechanism
Title: Dual functional roles of a novel bifunctional beta-lactamase/esterase from Lactococcus garvieae Le L, Yoo W, Wang Y, Jeon S, Kim KK, Kim HW, Kim TD Ref: Int J Biol Macromol, :, 2022 : PubMed
A novel bifunctional beta-lactamase/esterase (LgLacI), which is capable of hydrolyzing beta-lactam-containing antibiotics including ampicillin, oxacillin, and cefotaxime as well as synthesizing biodiesels, was cloned from Lactococcus garvieae. Unlike most bacterial esterases/lipases that have G-x-S-x-G motif, LgLacI, which contains S-x-x-K catalytic motif, has sequence similarities to bacterial family VIII esterase as well as beta-lactamases. The catalytic properties of LgLacI were explored using a wide range of biochemical methods including spectroscopy, assays, structural modeling, mutagenesis, and chromatography. We confirmed the bifunctional property of LgLacI hydrolyzing both esters and beta-lactam antibiotics. This study provides novel perspectives into a bifunctional enzyme from L. garvieae, which can degrade beta-lactam antibiotics with high esterase activity.
This report deals with the purification, characterization, and a preliminary crystallographic study of a novel cold-active esterase (HaEst1) from Halocynthiibacter arcticus. Primary sequence analysis reveals that HaEst1 has a catalytic serine in G-x-S-x-G motif. The recombinant HaEst1 was cloned, expressed, and purified. SDS-PAGE and zymographic analysis were carried out to characterize the properties of HaEst1. A single crystal of HaEst1 was obtained in a solution containing 10% (w/v) PEG 8000/8% ethylene glycol, 0.1 M Hepes-NaOH, pH 7.5. Diffraction data were collected to 2.10 A resolution with P21 space group. The final Rmerge and Rp.i.m values were 7.6% and 3.5% for 50-2.10 A resolution. The unit cell parameters were a = 35.69 A, b = 91.21 A, c = 79.15 A, and beta = 96.9deg
Title: Identification, characterization, and immobilization of a novel YbfF esterase from Halomonas elongata Yoo W, Kim B, Jeon S, Kim KK, Kim TD Ref: Int J Biol Macromol, 165:1139, 2020 : PubMed
The YbfF esterase family, which has a bifurcated binding pocket for diverse ligands, could serve as excellent biocatalysts in industrial and biotechnological applications. Here, the identification, characterization, and immobilization of a novel YbfF esterase (YbfF(Halomonas elongata)) from Halomonas elongata DSM 2581 is reported. Biochemical characterization of YbfF was carried out using activity staining, chromatographic analysis, kinetic analysis, activity assay, acetic acid release, and pH-indicator-based hydrolysis. YbfF(H.elongata) displayed broad substrate specificity, including that for p-nitrophenyl esters, glucose pentaacetate, tert-butyl acetate, and beta-lactam-containing compounds, with high efficiency. Based on a homology model of YbfF(H.elongata), Trp(237) in the substrate-binding pocket, a critical residue for catalytic activity and substrate specificity was identified and characterized. Furthermore, crosslinked enzyme aggregates and nanoflower formation were explored to enhance the chemical stability and recyclability of YbfF(H.elongata). The present study is the first report of a YbfF esterase from extremophiles, and explains its protein stability, catalytic activity, substrate specificities and diversities, kinetics, functional residues, amyloid formation, and immobilization.
Title: Characterization and mutation anaylsis of a cold-active bacterial hormone-sensitive lipase from Salinisphaera sp. P7-4 Kim BY, Yoo W, Huong Luu Le LT, Kim KK, Kim HW, Lee JH, Kim YO, Kim TD Ref: Archives of Biochemistry & Biophysics, 663:132, 2019 : PubMed
In mammals, hormone sensitive lipase (EC 3.1.1.79, HSL) catalyzes the hydrolysis of triacylglycerols as well as the modifications of a broad range of hydrophobic substrates containing ester linkages. HSLs are composed of an N-terminal ligand-binding domain and a C-terminal catalytic domain. Bacterial hormone-sensitive lipases (bHSLs), which are homologous to the C-terminal domain of mammalian HSLs, have a catalytic triad composed of Ser, His, and Asp. Here, a novel cold-active hormone-sensitive lipase (SaHSL) from Salinisphaera sp. P7-4 was identified, functionally characterized, and subjected to site-directed mutations. The enzymatic properties of SaHSL were investigated using several biochemical and biophysical methods. Interestingly, SaHSL exhibited the ability to act on a broad range of substrates including glyceryl tributyrate and glucose pentaacetate. Homology modeling and site-directed mutagenesis indicated that hydrophobic residues (Leu(156), Phe(164), and Val(204)) around the substrate-binding pocket were involved in substrate recognition. In addition, highly conserved amino acids (Glu(201), Arg(207), Leu(208), and Asp(227)) in the regulatory regions were found to be responsible for substrate specificity, thermostability, and enantioselectivity. In summary, this work provides new insights into the understanding of the C-terminal domain of HSL family and evidence that SaHSL can be used in a wide range of industrial applications.
BACKGROUND: S-Formylglutathione is hydrolyzed to glutathione and formate by an S-formylglutathione hydrolase (SFGH) (3.1.2.12). This thiol esterase belongs to the esterase family and is also known as esterase D. SFGHs contain highly conserved active residues of Ser-Asp-His as a catalytic triad at the active site. Characterization and investigation of SFGH from Antarctic organisms at the molecular level is needed for industrial use through protein engineering. RESULTS: A novel cold-active S-formylglutathione hydrolase (SfSFGH) from Shewanella frigidimarina, composed of 279 amino acids with a molecular mass of ~ 31.0 kDa, was characterized. Sequence analysis of SfSFGH revealed a conserved pentapeptide of G-X-S-X-G found in various lipolytic enzymes along with a putative catalytic triad of Ser148-Asp224-His257. Activity analysis showed that SfSFGH was active towards short-chain esters, such as p-nitrophenyl acetate, butyrate, hexanoate, and octanoate. The optimum pH for enzymatic activity was slightly alkaline (pH 8.0). To investigate the active site configuration of SfSFGH, we determined the crystal structure of SfSFGH at 2.32 A resolution. Structural analysis shows that a Trp182 residue is located at the active site entrance, allowing it to act as a gatekeeper residue to control substrate binding to SfSFGH. Moreover, SfSFGH displayed more than 50% of its initial activity in the presence of various chemicals, including 30% EtOH, 1% Triton X-100, 1% SDS, and 5 M urea. CONCLUSIONS: Mutation of Trp182 to Ala allowed SfSFGH to accommodate a longer chain of substrates. It is thought that the W182A mutation increases the substrate-binding pocket and decreases the steric effect for larger substrates in SfSFGH. Consequently, the W182A mutant has a broader substrate specificity compared to wild-type SfSFGH. Taken together, this study provides useful structure-function data of a SFGH family member and may inform protein engineering strategies for industrial applications of SfSFGH.
Title: Characterization, immobilization, and mutagenesis of a novel cold-active acetylesterase (EaAcE) from Exiguobacterium antarcticum B7 Wang Y, Le L, Yoo W, Lee CW, Kim KK, Lee JH, Kim TD Ref: Int J Biol Macromol, 136:1042, 2019 : PubMed
Cold-active enzymes with distinctive properties from a psychrophilic Exiguobacterium antarcticum B7 could be excellent biocatalysts in industrial and biotechnological processes. Here, the characterization, immobilization, and site-directed mutagenesis of a novel cold-active acetylesterase (EaAcE) from E. antarcticum B7 is reported. EaAcE does not belong to any currently known lipase/esterase family, although there are some sequence similarities with family III and V members. Biochemical characterization of EaAcE was carried out using activity staining, mass spectrometry analysis, circular dichroism spectra, freeze-thaw experiments, kinetic analysis, acetic acid release assays, and enantioselectivity determination. Furthermore, immobilization of EaAcE using four different approaches was explored to enhance its thermal stability and recyclability. Based on a homology model of EaAcE, four mutations (F45A, S118A, S141A, and T216A) within the substrate-binding pocket were investigated to elucidate their roles in EaAcE catalysis and substrate specificity. This work has provided invaluable information on the properties of EaAcE, which can now be used to understand the acetylesterase enzyme family.
Title: A novel enantioselective SGNH family esterase (NmSGNH1) from Neisseria meningitides: Characterization, mutational analysis, and ester synthesis Yoo W, Le L, Lee JH, Kim KK, Kim TD Ref: Biochimica & Biophysica Acta Molecular & Cellular Biology Lipids, 1864:1438, 2019 : PubMed
In Neisseria sp., SGNH family esterases are involved in bacterial pathogenesis as well as cell wall peptidoglycan maturation. Here, a novel enantioselective SGNH family esterase (NmSGNH1) from Neisseria meningitidis, which has sequence similarity to carbohydrate esterase (CE3) family, was catalytically characterized and functionally explored. NmSGNH1 exhibited a wide range of substrate specificities including naproxol acetate, tert-butyl acetate, glucose pentaacetate as well as p-nitrophenyl esters. Deletion of C-terminal residues (NmSGNH1Delta11) led to the altered substrate specificity, reduced catalytic activity, and increased thermostability. Furthermore, a hydrophobic residue of Leu(92) in the substrate-binding pocket was identified to be critical in catalytic activity, thermostability, kinetics, and enantioselectivity. Interestingly, immobilization of NmSGNH1 by hybrid nanoflowers (hNFs) and crosslinked enzyme aggregates (CLEAs) showed increased level of activity, recycling property, and enhanced stability. Finally, synthesis of butyl acetate, oleic acid esters, and fatty acid methyl esters (FAMEs) were verified. In summary, this work provides a molecular understanding of substrate specificities, catalytic regulation, immobilization, and industrial applications of a novel SGNH family esterase from Neisseria meningitidis.
Title: Crystal structure and functional characterization of a cold-active acetyl xylan esterase (PbAcE) from psychrophilic soil microbe Paenibacillus sp Park SH, Yoo W, Lee CW, Jeong CS, Shin SC, Kim HW, Park H, Kim KK, Kim TD, Lee JH Ref: PLoS ONE, 13:e0206260, 2018 : PubMed
Cold-active acetyl xylan esterases allow for reduced bioreactor heating costs in bioenergy production. Here, we isolated and characterized a cold-active acetyl xylan esterase (PbAcE) from the psychrophilic soil microbe Paenibacillus sp. R4. The enzyme hydrolyzes glucose penta-acetate and xylan acetate, reversibly producing acetyl xylan from xylan, and it shows higher activity at 4 degrees C than at 25 degrees C. We solved the crystal structure of PbAcE at 2.1-A resolution to investigate its active site and the reason for its low-temperature activity. Structural analysis showed that PbAcE forms a hexamer with a central substrate binding tunnel, and the inter-subunit interactions are relatively weak compared with those of its mesophilic and thermophilic homologs. PbAcE also has a shorter loop and different residue composition in the beta4-alpha3 and beta5-alpha4 regions near the substrate binding site. Flexible subunit movements and different active site loop conformations may enable the strong low-temperature activity and broad substrate specificity of PbAcE. In addition, PbAcE was found to have strong activity against antibiotic compound substrates, such as cefotaxime and 7-amino cephalosporanic acid (7-ACA). In conclusion, the PbAcE structure and our biochemical results provide the first example of a cold-active acetyl xylan esterase and a starting template for structure-based protein engineering.
Title: Identification, characterization, immobilization, and mutational analysis of a novel acetylesterase with industrial potential (LaAcE) from Lactobacillus acidophilus Wang Y, Ryu BH, Yoo W, Lee CW, Kim KK, Lee JH, Kim TD Ref: Biochimica & Biophysica Acta, 1862:197, 2018 : PubMed
Lactic acid bacteria, which are involved in the fermentation of vegetables, meats, and dairy products, are widely used for the productions of small organic molecules and bioactive peptides. Here, a novel acetylesterase (LaAcE) from Lactobacillus acidophilus NCFM was identified, functionally characterized, immobilized, and subjected to site-directed mutagenesis for biotechnological applications. The enzymatic properties of LaAcE were investigated using biochemical and biophysical methods including native polyacrylamide gel electrophoresis, acetic acid release, biochemical assays, enzyme kinetics, and spectroscopic methods. Interestingly, LaAcE exhibited the ability to act on a broad range of substrates including glucose pentaacetate, glyceryl tributyrate, fish oil, and fermentation-related compounds. Furthermore, immobilization of LaAcE showed good recycling ability and high thermal stability compared with free LaAcE. A structural model of LaAcE was used to guide mutational analysis of hydrophobic substrate-binding region, which was composed of Leu(156), Phe(164), and Val(204). Five mutants (L156A, F164A, V204A, L156A/F164A, and L156A/V204A) were generated and investigated to elucidate the roles of these hydrophobic residues in substrate specificity. This work provided valuable insights into the properties of LaAcE, and demonstrated that LaAcE could be used as a model enzyme of acetylesterase in lactic acid bacteria, making LaAcE a great candidate for industrial applications.
A novel microbial esterase, EaEST, from a psychrophilic bacterium Exiguobacterium antarcticum B7, was identified and characterized. To our knowledge, this is the first report describing structural analysis and biochemical characterization of an esterase isolated from the genus Exiguobacterium. Crystal structure of EaEST, determined at a resolution of 1.9 A, showed that the enzyme has a canonical alpha/beta hydrolase fold with an alpha-helical cap domain and a catalytic triad consisting of Ser96, Asp220, and His248. Interestingly, the active site of the structure of EaEST is occupied by a peracetate molecule, which is the product of perhydrolysis of acetate. This result suggests that EaEST may have perhydrolase activity. The activity assay showed that EaEST has significant perhydrolase and esterase activity with respect to short-chain p-nitrophenyl esters (<=C8), naphthyl derivatives, phenyl acetate, and glyceryl tributyrate. However, the S96A single mutant had low esterase and perhydrolase activity. Moreover, the L27A mutant showed low levels of protein expression and solubility as well as preference for different substrates. On conducting an enantioselectivity analysis using R- and S-methyl-3-hydroxy-2-methylpropionate, a preference for R-enantiomers was observed. Surprisingly, immobilized EaEST was found to not only retain 200% of its initial activity after incubation for 1 h at 80 degrees C, but also retained more than 60% of its initial activity after 20 cycles of reutilization. This research will serve as basis for future engineering of this esterase for biotechnological and industrial applications.
Title: Characterization of an Alkaline Family I.4 Lipase from Bacillus sp. W130-35 Isolated from a Tidal Mud Flat with Broad Substrate Specificity Kim HJ, Jung WK, Lee HW, Yoo W, Kim TD, Kim H Ref: J Microbiol Biotechnol, 25:2024, 2015 : PubMed
A gene encoding lipolytic enzyme, lip7-3, was isolated from Bacillus sp. W130-35 isolated from a tidal mud flat. The gene encoded a protein of 215 amino acids with a signal peptide composed of 34 amino acid residues. Lip7-3 belonged to the family I.4 lipase and showed its maximal activity at pH 9.0 and 60 degrees C. Its activity increased in the presence of 30% methanol and, remarkably, increased as well to 154.6% in the presence of Ca(2+). Lip7-3 preferred pnitrophenyl octanoate (C8) as a substrate and exhibited broad specificity for short- to longchain fatty acid esters. Additionally, Lip7-3 showed a low degree of enantioselectivity for an S-enantiomer (e.g., (S)-methyl-3-hydroxy-2-methylpropionate). It efficiently hydrolyzed glyceryl tributyrate, but did not hydrolyze glyceryl trioleate, fish oil, or olive oil. Its substrate specificity and activation by the solvent might offer a merit to the biotechnological enzyme applications like transesterification in the production of biodiesel.
