Deoxycholic acid degradation by a Pseudomonas sp. Acidic intermediates with A-ring unsaturation.
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ABSTRACT:
SUBMITTER: Leppik RA
PROVIDER: S-EPMC1154296 | biostudies-other | 1983 Mar
REPOSITORIES: biostudies-other
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Project description:The microbial catabolism of deoxycholic acid by a Pseudomonas species was studied, and three acidic products were isolated as their methyl esters. Evidence is presented that the compounds are methyl 3 alpha,12 alpha-dihydroxy-23,24-dinor-5 beta-cholan-22-oate, methyl 12 alpha-hydroxy-3-oxo-5 beta-cholan-24-oate and methyl 12 alpha-hydroxy-3-oxo-23,24-dinor-5 beta-cholan-22-oate.
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Project description:We identified the fatty acid synthesis (FAS) initiation enzyme in Pseudomonas aeruginosa as FabY, a ?-ketoacyl synthase KASI/II domain-containing enzyme that condenses acetyl coenzyme A (acetyl-CoA) with malonyl-acyl carrier protein (ACP) to make the FAS primer ?-acetoacetyl-ACP in the accompanying article (Y. Yuan, M. Sachdeva, J. A. Leeds, and T. C. Meredith, J. Bacteriol. 194:5171-5184, 2012). Herein, we show that growth defects stemming from deletion of fabY can be suppressed by supplementation of the growth media with exogenous decanoate fatty acid, suggesting a compensatory mechanism. Fatty acids eight carbons or longer rescue growth by generating acyl coenzyme A (acyl-CoA) thioester ?-oxidation degradation intermediates that are shunted into FAS downstream of FabY. Using a set of perdeuterated fatty acid feeding experiments, we show that the open reading frame PA3286 in P. aeruginosa PAO1 intercepts C(8)-CoA by condensation with malonyl-ACP to make the FAS intermediate ?-keto decanoyl-ACP. This key intermediate can then be extended to supply all of the cellular fatty acid needs, including both unsaturated and saturated fatty acids, along with the 3-hydroxyl fatty acid acyl groups of lipopolysaccharide. Heterologous PA3286 expression in Escherichia coli likewise established the fatty acid shunt, and characterization of recombinant ?-keto acyl synthase enzyme activity confirmed in vitro substrate specificity for medium-chain-length acyl CoA thioester acceptors. The potential for the PA3286 shunt in P. aeruginosa to curtail the efficacy of inhibitors targeting FabY, an enzyme required for FAS initiation in the absence of exogenous fatty acids, is discussed.
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Project description:Pseudomonas sp. strain ADP is the model strain for studying bacterial degradation of the s-triazine herbicide atrazine. In this work, we focused on the expression of the atzDEF operon, involved in mineralization of the central intermediate of the pathway, cyanuric acid. Expression analysis of atzD-lacZ fusions in Pseudomonas sp. strain ADP and Pseudomonas putida showed that atzDEF is subjected to dual regulation in response to nitrogen limitation and cyanuric acid. The gene adjacent to atzD, orf99 (renamed here atzR), encoding a LysR-like regulator, was found to be required for both responses. Expression of atzR-lacZ was induced by nitrogen limitation and repressed by AtzR. Nitrogen regulation of atzD-lacZ and atzR-lacZ expression was dependent on the alternative sigma factor sigmaN and NtrC, suggesting that the cyanuric acid degradation operon may be subject to general nitrogen control. However, while atzR is transcribed from a sigmaN-dependent promoter, atzDEF transcription appears to be driven from a sigma70-type promoter. Expression of atzR from a heterologous promoter revealed that although NtrC regulation of atzD-lacZ requires the AtzR protein, it is not the indirect result of NtrC-activated AtzR synthesis. We propose that expression of the cyanuric acid degradation operon atzDEF is controlled by means of a complex regulatory circuit in which AtzR is the main activator. AtzR activity is in turn modulated by the presence of cyanuric acid and by a nitrogen limitation signal transduced by the Ntr system.
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Project description:The microbial degradation of cholic acid by Pseudomonas sp. N.C.I.B. 10590 was studied, and two major products were isolated and identified as 7 alpha, 12 beta-dihydroxyandrosta-1,4-diene-3,17-dione and 7 alpha, 12 alpha-dihydroxy-3-oxopregna-1,4-diene-20-carboxylic acid. Four minor products were isolated and evidence is given for the following structures: 7 alpha, 12 alpha-dihydroxyandrosta-1,4-diene-3,17-dione, 12 beta-hydroxyandrosta-1,4,6-triene-3,17-dione, 7 alpha, 12 beta, 17 beta-trihydroxyandrosta-1,4-dien-3-one and 7 alpha, 12 alpha-dihydroxy-3-oxopregn-4-ene-20-carboxylic acid. The significance of the production of the steroid products is discussed, along with the possible enzymic mechanisms responsible for their production.
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Project description:The acenaphthylene-degrading bacterium Rhizobium sp. strain CU-A1 was isolated from petroleum-contaminated soil in Thailand. This strain was able to degrade 600 mg/liter acenaphthylene completely within three days. To elucidate the pathway for degradation of acenaphthylene, strain CU-A1 was mutagenized by transposon Tn5 in order to obtain mutant strains deficient in acenaphthylene degradation. Metabolites produced from Tn5-induced mutant strains B1, B5, and A53 were purified by thin-layer chromatography and silica gel column chromatography and characterized by mass spectrometry. The results suggested that this strain cleaved the fused five-membered ring of acenaphthylene to form naphthalene-1,8-dicarboxylic acid via acenaphthenequinone. One carboxyl group of naphthalene-1,8-dicarboxylic acid was removed to form 1-naphthoic acid which was transformed into salicylic acid before metabolization to gentisic acid. This work is the first report of complete acenaphthylene degradation by a bacterial strain.
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Project description:The bacterial degradation of cholic acid under anaerobic conditions by Pseudomonas sp. N.C.I.B. 10590 was studied. The major unsaturated neutral compound was identified as 12 beta-hydroxyandrosta-4,6-diene-3,17-dione, and the major unsaturated acidic metabolite was identified as 12 alpha-hydroxy-3-oxochola-4,6-dien-24-oic acid. Eight minor unsaturated metabolites were isolated and evidence is given for the following structures: 12 alpha-hydroxyandrosta-4,6-diene-3,17-dione, 12 beta,17 beta-dihydroxyandrosta-4,6-dien-3-one, 12 beta-hydroxyandrosta-1,4,6-triene-3,17-dione, 12 beta,17 beta-dihydroxyandrosta-1,4,6-trien-3-one, 12 beta-hydroxyandrosta-1,4,6-triene-3,17-dione, 12 beta,17 beta-dihydroxyandrosta-1,4,6-trien-3-one, 12 alpha-hydroxyandrosta-1,4-diene-3,17-dione, 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione, 3,12-dioxochola-4,6-dien-24-oic acid and 12 alpha-hydroxy-3-oxopregna-4,6-diene-20-carboxylic acid. In addition, a major saturated neutral compound was isolated and identified as 3 beta,12 beta-dihydroxy-5 beta-androstan-17-one, and the only saturated acidic metabolite was 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-cholan-24-oic acid. Nine minor saturated neutral compounds were also isolated, and evidence is presented for the following structures: 12 beta-hydroxy-5 beta-androstane-3,17-dione, 12 alpha-hydroxy-5 beta-androstane-3,17-dione, 3 beta,12 alpha-dihydroxy-5 beta-androstan-17-one, 3 alpha,12 beta-androstan-17-one, 3 alpha,12 alpha-dihydroxy-5 beta-androstan-17-one, 5 beta-androstane-3 beta,12 beta,17 beta-triol, 5 beta-androstane-3 beta,12 alpha,17 beta-triol, 5 beta-androstane-3 alpha,12 beta,17 beta-triol and 5 beta-androstane-3 alpha,12 alpha,17 beta-triol. The induction of 7 alpha-dehydroxylase and 12 alpha-dehydroxylase enzymes is discussed, together with the significance of dehydrogenation and ring fission under anaerobic conditions.
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Project description:Pseudomonas sp. QTF5 was isolated from the continuous permafrost near the bitumen layers in the Qiangtang basin of Qinghai-Tibetan Plateau in China (5,111?m above sea level). It is psychrotolerant and highly and widely tolerant to heavy metals and has the ability to metabolize benzoic acid and salicylic acid. To gain insight into the genetic basis for its adaptation, we performed whole genome sequencing and analyzed the resistant genes and metabolic pathways. Based on 120 published and annotated genomes representing 31 species in the genus Pseudomonas, in silico genomic DNA-DNA hybridization (<54%) and average nucleotide identity calculation (<94%) revealed that QTF5 is closest to Pseudomonas lini and should be classified into a novel species. This study provides the genetic basis to identify the genes linked to its specific mechanisms for adaptation to extreme environment and application of this microorganism in environmental conservation.
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