Title: Dechlorination of chloral hydrate is influenced by the biofilm adhesin protein LapA in Pseudomonas putida LF54 Zhang W, Huhe, Pan Y, Toyofuku M, Nomura N, Nakajima T, Uchiyama H Ref: Applied Environmental Microbiology, 79:4166, 2013 : PubMed
LapA is the largest surface adhesion protein of Pseudomonas putida that initiates biofilm formation. Here, by using transposon insertion mutagenesis and a conditional lapA mutant, we demonstrate for the first time that LapA influences chloral hydrate (CH) dechlorination in P. putida LF54.
Many poly(lactic acid) (PLA)-degrading microorganisms have been isolated from the natural environment by culture-based methods, but there is no study about unculturable PLA-degrading microorganisms. In this study, we constructed a metagenomic library consisting of the DNA extracted from PLA disks buried in compost. We identified three PLA-degrading genes encoding lipase or hydrolase. The purified enzymes degraded not only PLA, but also various aliphatic polyesters, tributyrin, and p-nitrophenyl esters. From their substrate specificities, the PLA depolymerases were classified into an esterase rather than a lipase. Among the PLA depolymerases, PlaM4 exhibited thermophilic properties; that is, it showed the highest activity at 70 degrees C and was stable even after incubation for 1 h at 50 degrees C. PlaM4 had absorption and degradation activities for solid PLA at 60 degrees C, which indicates that the enzyme can effectively degrade PLA in a high-temperature environment. On the other hand, the enzyme classification based on amino acid sequences showed that the other PLA depolymerases, PlaM7 and PlaM9, were not classified into known lipases or esterases. This is the first report on the identification and characterization of PLA depolymerase from a metagenome.
A bacterium which degrades urethane compounds was isolated and identified as Rhodococcus equi strain TB-60. Strain TB-60 degraded toluene-2,4-dicarbamic acid dibutyl ester (TDCB) and accumulated toluene diamine as the degradation product. The enzyme which cleaves urethane bond in TDCB was strongly induced by acetanilide. The purified enzyme (urethane hydrolase) was found to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight was estimated to be 55 kDa. The optimal temperature and pH were 45 degrees C and 5.5, respectively. The enzyme hydrolyzed aliphatic urethane compound as well as aromatic ones. The activity was inhibited by HgCl(2), p-chrolomercuribenzoic acid, and phenylmethylsulfonyl fluoride, suggesting that cysteine and/or serine residues play an important role in the activity. The enzyme catalyzed the hydrolysis of anilides, amides, and esters as well as TDCB. It was characterized as a novel amidase/esterase, differing in some properties from other known amidases/esterases.
Title: Lysophospholipase I identified as a ghrelin deacylation enzyme in rat stomach Shanado Y, Kometani M, Uchiyama H, Koizumi S, Teno N Ref: Biochemical & Biophysical Research Communications, 325:1487, 2004 : PubMed
Ghrelin, discovered in rat stomach as an endogenous growth hormone secretagogue, is octanoylated at the Ser3 residue. Since this octanoylation is essential for the functions of ghrelin, the enzymes that catalyze acylation for ghrelin biosynthesis and deacylation (deactivation step) must be considered as important regulators. We found that rat stomach homogenate contained ghrelin deacylation activity, and we isolated the active fractions by column chromatography. After sequencing and expressing candidate proteins, the ghrelin deacylation enzyme in the stomach was identified as lysophospholipase I (LysoPLA I). The enzyme properties were examined using recombinant rat LysoPLA I expressed in Escherichia coli. K(m) and V(max) values were determined as 6.5 microM and 2.3 micromol/min/mg for ghrelin and 2.2 x 10(2) microM and 0.5 micromol/min/mg for lysophosphatidylcholine (LysoPC), respectively. The deacylation of both substrates was inhibited by methyl arachidonyl fluorophosphonate (MAFP), which is known as an irreversible inhibitor of LysoPLA I. These results reveal that LysoPLA I catalyzes the removal of n-octanoic acid from ghrelin to form des-acyl ghrelin. Identification of the ghrelin deacylation enzyme in the stomach and a deacylation inhibitor will be helpful in investigating ghrelin biosynthesis.
The gene encoding a poly(DL-lactic acid) (PLA) depolymerase from Paenibacillus amylolyticus strain TB-13 was cloned and overexpressed in Escherichia coli. The purified recombinant PLA depolymerase, PlaA, exhibited degradation activities toward various biodegradable polyesters, such as poly(butylene succinate), poly(butylene succinate-co-adipate), poly(ethylene succinate), and poly(epsilon-caprolactone), as well as PLA. The monomeric lactic acid was detected as the degradation product of PLA. The substrate specificity toward triglycerides and p-nitrophenyl esters indicated that PlaA is a type of lipase. The gene encoded 201 amino acid residues, including the conserved pentapeptide Ala-His-Ser-Met-Gly, present in the lipases of mesophilic Bacillus species. The identity of the amino acid sequence of PlaA with Bacillus lipases was no more than 45 to 50%, and some of its properties were different from those of these lipases.
Microorganisms isolated from soil samples were screened for their ability to degrade various biodegradable polyester-based plastics. The most active strain, designated as strain TB-13, was selected as the best strain for degrading these plastics. From its phenotypic and genetic characteristics, strain TB-13 was closely related to Paenibacillus amyloyticus. It could degrade poly(lactic acid), poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone) and poly(ethylene succinate) but not poly(hydroxybutylate-co-valerate). However, it could not utilize these plastics as sole carbon sources. Both protease and esterase activities, which may be involved in the degradation of plastic, were constitutively detected in the culture broth.
OBJECTIVES: Dementia associated with Lewy bodies in cortical and subcortical areas is classified as dementia of the non-Alzheimer type and termed diffuse Lewy body disease (DLBD). The generic term "dementia with Lewy bodies (DLB)" was proposed in the international workshop on Lewy body dementia to include the similar disorders presenting Lewy bodies. In DLB, a lower level of choline acetyltransferase (ChAT) activity in the neocortex was found compared with that in Alzheimer's disease. The purpose of the present study was to determine the total amount of muscarinic acetylcholine receptors (mAChRs) and relative proportion of each subtype (m1-m4) of mAChRs in the frontal and temporal cortex of seven DLBD and 11 Alzheimer's disease necropsied brains. METHODS: A [(3)H]quinuclidinyl benzilate (QNB) binding assay and an immunoprecipitation assay using subtype-specific antibodies were performed. Each antibody was raised against fusion proteins containing peptides corresponding to the third intracellular (i3) loops of the respective mAChR subtype. RESULTS: The total amounts of mAChRs were significantly lower in the preparations of temporal cortices from DLBD and Alzheimer's disease than in those from dead controls (seven cases). In both diseases, the proportion of the m3 receptor in the frontal cortex was significantly increased and that of the m4 receptor in the temporal cortex was significantly decreased compared with the control specimens. The proportions of the m1 and m2 subtypes were significantly different in the temporal cortex. The proportion of the m1 receptor was significantly greater in the DLBD brains, whereas that of the m2 receptor was significantly greater in the Alzheimer's disease brains than in the controls. CONCLUSIONS: The m1 receptor is the major subtype in the cerebral cortex, and m2 is known to be present at presynaptic terminals. The higher proportions of m1 in DLBD and m2 in Alzheimer's disease suggest that the manner of degeneration in the cholinergic system is different between the diseases. It is hypothesised that a severe depletion of presynaptic cholinergic projective neurons causes the upregulation of m1 receptor in the temporal cortex in DLBD.
Title: Phosphorylation of human m1 muscarinic acetylcholine receptors by G protein-coupled receptor kinase 2 and protein kinase C Haga K, Kameyama K, Haga T, Kikkawa U, Shiozaki K, Uchiyama H Ref: Journal of Biological Chemistry, 271:2776, 1996 : PubMed
Human muscarinic acetylcholine receptor m1 subtypes (m1 receptors) were expressed in and purified from insect Sf9 cells and then subjected to phosphorylation by G protein-coupled receptor kinase 2 (GRK2) expressed in and purified from Sf9 cells and by protein kinase C purified from rat brain (a mixture of alpha, beta, and gamma types, PKC). The m1 receptor was phosphorylated by either GRK2 or PKC in an agonist-dependent or independent manner, respectively. G protein beta gamma subunits stimulated the phosphorylation by GRK2 but did not affect the phosphorylation by PKC. The number of incorporated phosphates was 4.6 and 2.8 mol/mol of receptor for phoshorylation by GRK2 and PKC, respectively. The number of incorporated phosphates was 7.5 mol/mol receptor for phosphorylation by GRK2 followed by PKC, but was 5.8 mol/mol of receptor for the phosphorylation by PKC followed by GRK2. Major sites phosphorylated by GRK2 and PKC were located in the third intracellular loop and the carboxyl-terminal tail, respectively. These results indicate that GRK2 and PKC phosphorylate different sites of m1 receptors and that the phosphorylation by PKC partially inhibits the phosphorylation by GRK2, probably by affecting activation of GRK2 by agonist-bound receptors.
