Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In a previous work, we have investigated the effect of amplifying individually the genes of the threonine biosynthetic pathway on threonine accumulation by yeast. Here, we present the results of the simultaneous amplification of these genes in strains with different genetic backgrounds. These strains carry a mutant HOM3-R2 allele (coding for a feedback-insensitive aspartate kinase), and/or a mutant cha1 allele that makes it defective in threonine degradation by the catabolic L-serine (L-threonine) deaminase. The results show that the amplification of the clustered genes affects threonine and homoserine accumulation only when it includes the HOM3 gene, or when combined with a HOM3-R2 mutation. Similarly, the cha1 mutation is only effective when a certain amount of threonine is reached. Threonine overproduction affects other cellular functions such as the accumulation of other amino acids, the cell growth and metabolite excretion, probably reflecting a redirection of the carbon flux in the central metabolism.
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PMID:Enrichment of threonine content in Saccharomyces cerevisiae by pathway engineering. 1086 83

Porcine kidney acylase I was shown to be able to deacylate N-acylhomoserine lactones, a family of chemicals employed by Gram-negative bacteria as quorum-sensing molecules for cell population density-dependent growth (such as biofilm formation). The enzyme transformed both N-butyryl-and N-octanoyl-L-homoserine lactones into L-homoserine. An optimal pH of 10 at 23 degrees C and an optimal temperature of 76 degrees C at pH 9 were found for the enzyme in hydrolyzing N-butyryl-homoserine lactone. At pH 9 and 23 degrees C, the enzymatic catalysis had a K(m) of 81+/-3 mM and a k(cat) of 127+/-2 nmol min(-1) per mg. The enzyme was also shown to be able to reduce the biofilm growth in an aquarium water sample. Potential physiological significance and medicinal/industrial applications of the N-acylhomoserine lactone-degrading activity of acylase are discussed.
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PMID:Degradation of N-acylhomoserine lactones, the bacterial quorum-sensing molecules, by acylase. 1252 73

Acyl-homoserine lactones (AHLs) are employed by several Proteobacteria as quorum-sensing signals. Past studies have established that these compounds are subject to biochemical decay and can be used as growth nutrients. Here we describe the isolation of a soil bacterium, Pseudomonas strain PAI-A, that degrades 3-oxododecanoyl-homoserine lactone (3OC12HSL) and other long-acyl, but not short-acyl, AHLs as sole energy sources for growth. The small-subunit rRNA gene from strain PAI-A was 98.4% identical to that of Pseudomonas aeruginosa, but the soil isolate did not produce obvious pigments or AHLs or grow under denitrifying conditions or at 42 degrees C. The quorum-sensing bacterium P. aeruginosa, which produces both 3OC12HSL and C4HSL, was examined for the ability to utilize AHLs for growth. It did so with a specificity similar to that of strain PAI-A, i.e., degrading long-acyl but not short-acyl AHLs. In contrast to the growth observed with strain PAI-A, P. aeruginosa strain PAO1 growth on AHLs commenced only after extremely long lag phases. Liquid-chromatography-atmospheric pressure chemical ionization-mass spectrometry analyses indicate that strain PAO1 degrades long-acyl AHLs via an AHL acylase and a homoserine-generating HSL lactonase. A P. aeruginosa gene, pvdQ (PA2385), has previously been identified as being a homologue of the AHL acylase described as occurring in a Ralstonia species. Escherichia coli expressing pvdQ catalyzed the rapid inactivation of long-acyl AHLs and the release of HSL. P. aeruginosa engineered to constitutively express pvdQ did not accumulate its 3OC12HSL quorum signal when grown in rich media. However, pvdQ knockout mutants of P. aeruginosa were still able to grow by utilizing 3OC12HSL. To our knowledge, this is the first report of the degradation of AHLs by pseudomonads or other gamma-Proteobacteria, of AHL acylase activity in a quorum-sensing bacterium, of HSL lactonase activity in any bacterium, and of AHL degradation with specificity only towards AHLs with long side chains.
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PMID:Utilization of acyl-homoserine lactone quorum signals for growth by a soil pseudomonad and Pseudomonas aeruginosa PAO1. 1453 48

The Burkholderia cepacia epidemic strain marker (BCESM) is a useful epidemiological marker for virulent B. cenocepacia strains that infect patients with cystic fibrosis. However, there was no evidence that the original marker, identified by random amplified polymorphic DNA fingerprinting, contributed to pathogenicity. Here we demonstrate that the BCESM is part of a novel genomic island encoding genes linked to both virulence and metabolism. The BCESM was present on a 31.7-kb low-GC-content island that encoded 35 predicted coding sequences (CDSs): an N-acyl homoserine lactone (AHL) synthase gene (cciI) and corresponding transcriptional regulator (cciR), representing the first time cell signaling genes have been found on a genomic island; fatty acid biosynthesis genes; an IS66 family transposase; transcriptional regulator CDSs; amino acid metabolism genes; and a group of hypothetical genes. Mutagenesis of the AHL synthase, amidase (amiI), and porin (opcI) genes on the island was carried out. Testing of the isogenic mutants in a rat model of chronic lung infection demonstrated that the amidase played a role in persistence, while the AHL synthase and porin were both involved in virulence. The island, designated the B. cenocepacia island (cci), is the first genomic island to be defined in the B. cepacia complex and its discovery validates the original epidemiological correlation of the BCESM with virulent CF strains. The features of the cci, which overlap both pathogenicity and metabolism, expand the concept of bacterial pathogenicity islands and illustrate the diversity of accessory functions that can be acquired by lateral gene transfer in bacteria.
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PMID:The Burkholderia cepacia epidemic strain marker is part of a novel genomic island encoding both virulence and metabolism-associated genes in Burkholderia cenocepacia. 1497 60

N-acylhomoserine lactones (AHLs) play an important role in regulating virulence factors in pathogenic bacteria. Recently, the enzymatic inactivation of AHLs, which can be used as antibacterial targets, has been identified in several soil bacteria. In this study, strain M664, identified as a Streptomyces sp., was found to secrete an AHL-degrading enzyme into a culture medium. The ahlM gene for AHL degradation from Streptomyces sp. strain M664 was cloned, expressed heterologously in Streptomyces lividans, and purified. The enzyme was found to be a heterodimeric protein with subunits of approximately 60 kDa and 23 kDa. A comparison of AhlM with known AHL-acylases, Ralstonia strain XJ12B AiiD and Pseudomonas aeruginosa PAO1 PvdQ, revealed 35% and 32% identities in the deduced amino acid sequences, respectively. However, AhlM was most similar to the cyclic lipopeptide acylase from Streptomyces sp. strain FERM BP-5809, exhibiting 93% identity. A mass spectrometry analysis demonstrated that AhlM hydrolyzed the amide bond of AHL, releasing homoserine lactone. AhlM exhibited a higher deacylation activity toward AHLs with long acyl chains rather than short acyl chains. Interestingly, AhlM was also found to be capable of degrading penicillin G by deacylation, showing that AhlM has a broad substrate specificity. The addition of AhlM to the growth medium reduced the accumulation of AHLs and decreased the production of virulence factors, including elastase, total protease, and LasA, in P. aeruginosa. Accordingly, these results suggest that AHL-acylase, AhlM could be effectively applied to the control of AHL-mediated pathogenicity.
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PMID:Identification of extracellular N-acylhomoserine lactone acylase from a Streptomyces sp. and its application to quorum quenching. 1587 Mar 55

The relevance of the acyl homoserine lactone (acyl-HSL) quorum signals N-3-oxododecanoyl-homoserine lactone (3OC12HSL) and N-butanoyl-homoserine lactone to the biology and virulence of Pseudomonas aeruginosa is well investigated. Previously, P. aeruginosa was shown to degrade long-chain, but not short-chain, acyl-HSLs as sole carbon and energy sources (J. J. Huang, J.-I. Han, L.-H. Zhang, and J. R. Leadbetter, Appl. Environ. Microbiol. 69:5941-5949, 2003). A gene encoding an enzyme with acyl-HSL acylase activity, pvdQ (PA2385), was identified, but it was not required for acyl-HSL utilization. This indicated that P. aeruginosa encodes another acyl-HSL acylase, which we identify here. A comparison of total cell proteins of cultures grown with long-acyl acyl-HSLs versus other substrates implicated the involvement of a homolog of PvdQ, the product of gene PA1032, for which we propose the name QuiP. Transposon mutants of quiP were defective for growth when P. aeruginosa was cultured in medium containing decanoyl-HSL as a sole carbon and energy source. Complementation with a functional copy of quiP rescued this growth defect. When P. aeruginosa was grown in buffered lysogeny broth, constitutive expression of QuiP in P. aeruginosa led to decreased accumulations of the quorum signal 3OC12HSL, relative to the wild type. Heterologous expression of QuiP was sufficient to confer long-chain acyl-HSL acylase activity upon Escherichia coli. Examination of gene expression patterns during acyl-HSL-dependent growth of P. aeruginosa further supported the involvement of quiP in signal decay and revealed other genes also possibly involved. It is not yet known under which "natural" conditions quiP is expressed or how P. aeruginosa balances the expression of its quorum-sensing systems with the expression of its acyl-HSL acylase activities.
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PMID:Identification of QuiP, the product of gene PA1032, as the second acyl-homoserine lactone acylase of Pseudomonas aeruginosa PAO1. 1646 66

The virulence of the opportunistic human pathogen Pseudomonas aeruginosa PAO1 is controlled by an N-acyl-homoserine lactone (AHL)-dependent quorum-sensing system. During functional analysis of putative acylase genes in the P. aeruginosa PAO1 genome, the PA2385 gene was found to encode an acylase that removes the fatty acid side chain from the homoserine lactone (HSL) nucleus of AHL-dependent quorum-sensing signal molecules. Analysis showed that the posttranslational processing of the acylase and the hydrolysis reaction type are similar to those of the beta-lactam acylases, strongly suggesting that the PA2385 protein is a member of the N-terminal nucleophile hydrolase superfamily. In a bioassay, the purified acylase was shown to degrade AHLs with side chains ranging in length from 11 to 14 carbons at physiologically relevant low concentrations. The substituent at the 3' position of the side chain did not affect activity, indicating broad-range AHL quorum-quenching activity. Of the two main AHL signal molecules of P. aeruginosa PAO1, N-butanoyl-l-homoserine lactone (C4-HSL) and N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C12-HSL), only 3-oxo-C12-HSL is degraded by the enzyme. Addition of the purified protein to P. aeruginosa PAO1 cultures completely inhibited accumulation of 3-oxo-C12-HSL and production of the signal molecule 2-heptyl-3-hydroxy-4(1H)-quinolone and reduced production of the virulence factors elastase and pyocyanin. Similar results were obtained when the PA2385 gene was overexpressed in P. aeruginosa. These results demonstrate that the protein has in situ quorum-quenching activity. The quorum-quenching AHL acylase may enable P. aeruginosa PAO1 to modulate its own quorum-sensing-dependent pathogenic potential and, moreover, offers possibilities for novel antipseudomonal therapies.
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PMID:Quorum quenching by an N-acyl-homoserine lactone acylase from Pseudomonas aeruginosa PAO1. 1649 38

Comamonas strain D1 enzymatically inactivates quorum-sensing (QS) signal molecules of the N-acyl homoserine lactone (N-AHSL) family, and exhibits the broadest inactivation range of known bacteria. It degrades N-AHSL with acyl-side chains ranging from 4 to 16 carbons, with or without 3-oxo or 3-hydroxy substitutions. N-AHSL degradation yields HSL but not N-acyl homoserine: strain D1 therefore harbors an amidohydrolase activity. Strain D1 is the fifth bacterium species in which an N-AHSL amidohydrolase is described. Consistent with its N-AHSL degradation ability, strain D1 efficiently quenches various QS-dependent functions in other bacteria, such as violacein production by Chromobacterium violaceum and pathogenicity and antibiotic production in Pectobacterium.
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PMID:N-acyl homoserine lactones are degraded via an amidolytic activity in Comamonas sp. strain D1. 1713 82

A gene involved in N-acyl homoserine lactone (N-AHSL) degradation was identified by screening a genomic library of Rhodococcus erythropolis strain W2. This gene, named qsdA (for quorum-sensing signal degradation), encodes an N-AHSL lactonase unrelated to the two previously characterized N-AHSL-degrading enzymes, i.e., the lactonase AiiA and the amidohydrolase AiiD. QsdA is related to phosphotriesterases and constitutes the reference of a novel class of N-AHSL degradation enzymes. It confers the ability to inactivate N-AHSLs with an acyl chain ranging from C(6) to C(14), with or without substitution at carbon 3. Screening of a collection of 15 Rhodococcus strains and strains closely related to this genus clearly highlighted the relationship between the ability to degrade N-AHSLs and the presence of the qsdA gene in Rhodococcus. Bacteria harboring the qsdA gene interfere very efficiently with quorum-sensing-regulated functions, demonstrating that qsdA is a valuable tool for developing quorum-quenching procedures.
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PMID:A Rhodococcus qsdA-encoded enzyme defines a novel class of large-spectrum quorum-quenching lactonases. 1819 19

Many Gram-negative bacterial pathogens employ N-acyl homoserine lactones (AHLs) quorum-sensing signals for regulation of various biological functions. Several types of AHL-inactivating enzymes, also known as quorum-quenching enzymes, have been unveiled in recent years. These enzymes seem to play important roles in microbial physiology and ecology and hold promising potential in biotechnology. This unit describes methods based on a simple diffusion plate assay for qualitative detection and quantitative measurement of AHL-inactivating enzyme activity. The qualitative detection method is suitable for rapid and large-scale screening and identification of quorum-quenching enzymes. Furthermore, HPLC methods are provided for accurate determination of whether the quorum-quenching enzyme is a lactonase or an acylase. The unit also presents concise background information on the quorum-quenching enzymes identified from various sources, including bacterial and mammalian species.
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PMID:Detection and analysis of quorum-quenching enzymes against acyl homoserine lactone quorum-sensing signals. 1877 Jun


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