Branched-chain amino acid catabolism in bacteria.

Massey, L K; Sokatch, John R.; Conrad, Robert

doi:10.1128/mmbr.40.1.42-54.1976

Cited by 129 publications

(81 citation statements)

References 20 publications

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“…In bacteria, the initial step in BCAA catabolism, the deamination reaction, is catalysed by leucine oxidase, leucine dehydrogenase or BCAA aminotransferase (Massey et al 1976). We found that CE from S. xylosus converted leucine to KIC only in the presence of an a-ketoacid and pyridoxal 5¢-phosphate indicating a transaminase to be responsible for this reaction.…”

Section: Discussionmentioning

confidence: 83%

“…A number of enzymes capable of initiating the initial step in the catabolism of BCAAs in bacteria have been described. These include aminotransferases, dehydrogenases and oxidases (Massey et al 1976). They catalyse the deamination of the BCAAs to their corresponding a-ketoacids, a-ketoisocaproic acid (KIC) from leucine, a-ketoisovaleric acid (KIV) from valine and a-ketob-methylvaleric acid (KMV) from isoleucine.…”

Section: Introductionmentioning

confidence: 99%

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Catabolism of leucine to branched-chain fatty acids in Staphylococcus xylosus

Beck

Hansen²,

Lauritsen

2004

J Appl Microbiol

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Aims: Staphylococcus xylosus is an important starter culture in the production of flavours from the branched-chain amino acids leucine, valine and isoleucine in fermented meat products. The sensorially most important flavour compounds are the branched-chain aldehydes and acids derived from the corresponding amino acids and this paper intends to perspectivate these flavour compounds in the context of leucine metabolism. Methods and Results: GC and GC/MS analysis combined with stable isotope labelling was used to study leucine catabolism. This amino acid together with valine and isoleucine was used as precursors for the production of branched-chain fatty acids for cell membrane biosynthesis during growth. A 83AE3% of the cellular fatty acids were branched. The dominating fatty acid was anteiso-C 15:0 that constituted 55% of the fatty acids. A pyridoxal 5¢-phosphate and a-ketoacid dependent reaction catalysed the deamination of leucine, valine and isoleucine into their corresponding a-ketoacids. As a-amino group acceptor a-keto-b-methylvaleric acid and a-ketoisovaleric acid was much more efficient than a-ketoglutarate. The sensorially and metabolic key intermediate on the pathway to the branched-chain fatty acids, 3-methylbutanoic acid was produced from leucine at the onset of the stationary growth phase and then, when the growth medium became scarce in leucine, from the oxidation of glucose via pyruvate. Conclusions: This paper demonstrates that the sensorially important branched-chain aldehydes and acids are important intermediates on the metabolic route leading to branched-chain fatty acids for cell membrane biosynthesis. Significance and Impact of the Study: The metabolic information obtained is extremely important in connection with a future biotechnological design of starter cultures for production of fermented meat.

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Section: Discussionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Catabolism of leucine to branched-chain fatty acids in Staphylococcus xylosus

Beck

Hansen²,

Lauritsen

2004

J Appl Microbiol

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“…They proposed conversion of the product of these reactions, 2-glutathionlyl -2-methyl-3-butenoic acid, to the coenzyme A thioester, followed by removal of the glutathione moiety, possibly catalysed by IsoG and IsoJ. This product could plausibly be broken down into acetyl CoA and propionyl CoA, possibly sharing enzymes with the latter part of the isoleucine degradation pathway (Massey et al, 1976).…”

Section: Resultsmentioning

confidence: 99%

Regulation of plasmid‐encoded isoprene metabolism in Rhodococcus, a representative of an important link in the global isoprene cycle

Crombie

Khawand

Rhodius

et al. 2015

Environmental Microbiology

127

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SummaryEmissions of biogenic volatile organic compounds (VOCs) form an important part of the global carbon cycle, comprising a significant proportion of net ecosystem productivity. They impact atmospheric chemistry and contribute directly and indirectly to greenhouse gases. Isoprene, emitted largely from plants, comprises one third of total VOCs, yet in contrast to methane, which is released in similar quantities, we know little of its biodegradation. Here, we report the genome of an isoprene degrading isolate, Rhodococcus sp. AD45, and, using mutagenesis shows that a plasmid-encoded soluble di-iron centre isoprene monooxygenase (IsoMO) is essential for isoprene metabolism. Using RNA sequencing (RNAseq) to analyse cells exposed to isoprene or epoxyisoprene in a substrate-switch time-course experiment, we show that transcripts from 22 contiguous genes, including those encoding IsoMO, were highly upregulated, becoming among the most abundant in the cell and comprising over 25% of the entire transcriptome. Analysis of gene transcription in the wild type and an IsoMO-disrupted mutant strain showed that epoxyisoprene, or a subsequent product of isoprene metabolism, rather than isoprene itself, was the inducing molecule. We provide a foundation of molecular data for future research on the environmental biological consumption of this important, climate-active compound.

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“…Furthermore, the proposed reductive elimination of glutathione would be greatly facilitated by replacement of the carboxylate of HGMBA with a more electron-withdrawing thioester. Removal of glutathione from the CoA thioester of HGMBA would provide 2-methyl-3-butenyl CoA, which is an intermediate of the isoleucine degradation pathway (Massey et al, 1976). Further metabolism of 2-methyl-3-butenyl CoA by a b-oxidation pathway would then yield acetyl-CoA and propionyl-CoA, which can be oxidized by central metabolic pathways.…”

Section: The Biochemical Pathway For Isoprene Degradationmentioning

confidence: 99%