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Transacylation as a chain-termination mechanism in fatty acid synthesis by mammalian fatty acid synthetase. Synthesis of medium-chain-length (C8-C12) acyl-CoA esters by goat mammary-gland fatty acid synthetase.

ABSTRACT: 1. Ruminant mammary-gland fatty acid synthetases can, in contrast with non-ruminant mammary enzymes, synthesize medium-chain fatty acids. 2. Medium-chain fatty acids are only synthesized in the presence of a fatty acid-removing system such as albumin, beta-lactoglobulin or methylated cyclodextrin. 3. The short- and medium-chain fatty acids synthesized were released as acyl-CoA esters from the fatty acid synthetase.

SUBMITTER: Knudsen J

PROVIDER: S-EPMC1158083 | biostudies-other | 1982 Jan

REPOSITORIES: biostudies-other

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Medium-chain fatty acid synthesis by goat mammary-gland fatty acid synthetase. The effect of limited proteolysis.

Project description:Fatty acid synthetase from goat mammary gland was subjected to limited proteolysis by trypsin and elastase. Both proteolytic enzymes selectively cleaved the chain-terminating thioester hydrolase component from the enzyme complex, leaving all other partial activities intact in the core peptides. Trypsin, but not elastase, caused extensive degradation of the released thioester hydrolase. The released thioester hydrolase could be purified to homogeneity by gel filtration. The molecular weight was estimated as 29 000 and the enzyme showed only significant hydrolytic activity toward long-chain acyl-CoA esters. The core peptides retained the ability to synthesize medium-chain acyl-CoA esters in the presence of 2,6-di-O-methyl-alpha-cyclodextrin. The results conclusively show that the terminating thioester hydrolase of goat mammary-gland fatty acid synthetase is not involved in termination of medium-chain-length fatty acid synthesis by this enzyme.

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Medium chain fatty acid (MCFAs) synthesis

Project description:Medium chain fatty acid (MCFAs) synthesis Metagenome

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Transacylation as a chain-termination mechanism in fatty acid synthesis by mammalian fatty acid synthetase. Synthesis of butyrate and hexanoate by lactating cow mammary gland fatty acid synthetase.

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Project description:Persisters represent a small bacterial population that is dormant and that survives under antibiotic treatment without experiencing genetic adaptation. Persisters are also considered one of the major reasons for recalcitrant chronic bacterial infections. Although several mechanisms of persister formation have been proposed, it is not clear how cells enter the dormant state in the presence of antibiotics or how persister cell formation can be effectively controlled. A fatty acid compound, cis-2-decenoic acid, was reported to decrease persister formation as well as revert the dormant cells to a metabolically active state. We reasoned that some fatty acid compounds may be effective in controlling bacterial persistence because they are known to benefit host immune systems. This study investigated persister cell formation by pathogens that were exposed to nine fatty acid compounds during antibiotic treatment. We found that three medium chain unsaturated fatty acid ethyl esters (ethyl trans-2-decenoate, ethyl trans-2-octenoate, and ethyl cis-4-decenoate) decreased the level of Escherichia coli persister formation up to 110-fold when cells were exposed to ciprofloxacin or ampicillin antibiotics. RNA sequencing analysis and gene deletion persister studies elucidated that these fatty acids inhibit bacterial persistence by regulating antitoxin HipB. A similar persister cell reduction was observed for pathogenic E. coli EDL933, Pseudomonas aeruginosa PAO1, and Serratia marcescens ICU2-4 strains. This study demonstrates that fatty acid ethyl esters can be used to disrupt bacterial dormancy to combat persistent infectious diseases.

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Evidence that the medium-chain acyltransferase of lactating-goat mammary-gland fatty acid synthetase is identical with the acetyl/malonyltransferase.

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Engineering carboxylic acid reductase for selective synthesis of medium-chain fatty alcohols in yeast.

Project description:Medium-chain fatty alcohols (MCFOHs, C6 to C12) are potential substitutes for fossil fuels, such as diesel and jet fuels, and have wide applications in various manufacturing processes. While today MCFOHs are mainly sourced from petrochemicals or plant oils, microbial biosynthesis represents a scalable, reliable, and sustainable alternative. Here, we aim to establish a Saccharomyces cerevisiae platform capable of selectively producing MCFOHs. This was enabled by tailoring the properties of a bacterial carboxylic acid reductase from Mycobacterium marinum (MmCAR). Extensive protein engineering, including directed evolution, structure-guided semirational design, and rational design, was implemented. MmCAR variants with enhanced activity were identified using a growth-coupled high-throughput screening assay relying on the detoxification of the enzyme's substrate, medium-chain fatty acids (MCFAs). Detailed characterization demonstrated that both the specificity and catalytic activity of MmCAR was successfully improved and a yeast strain harboring the best MmCAR variant generated 2.8-fold more MCFOHs than the strain expressing the unmodified enzyme. Through deletion of the native MCFA exporter gene TPO1, MCFOH production was further improved, resulting in a titer of 252 mg/L for the final strain, which represents a significant improvement in MCFOH production in minimal medium by S. cerevisiae.

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Project description:Medium-chain triglycerides (MCTs) are an emerging choice to treat neurodegenerative disorders such as Alzheimer's disease. They are triesters of glycerol and three medium-chain fatty acids, such as capric (C8) and caprylic (C10) acids. The availability of C8-C10 methyl esters (C8-C10 ME) from vegetable oil processes has presented an opportunity to use methyl esters as raw materials for the synthesis of MCTs. However, there are few reports on enzymes that can efficiently hydrolyse C8-C10 ME to industrial specifications. Here, we report the discovery and identification of a novel lipase from Lasiodiplodia theobromae fungus (LTL1), which hydrolyses C8-C10 ME efficiently. LTL1 can perform hydrolysis over pH ranges from 3.0 to 9.0 and maintain thermotolerance up to 70 °C. It has high selectivity for monoesters over triesters and displays higher activity over commercially available lipases for C8-C10 ME to achieve 96.17% hydrolysis within 31 h. Structural analysis by protein X-ray crystallography revealed LTL1's well-conserved lipase core domain, together with a partially resolved N-terminal subdomain and an inserted loop, which may suggest its hydrolytic preference for monoesters. In conclusion, our results suggest that LTL1 provides a tractable route towards to production of C8-C10 fatty acids from methyl esters for the synthesis of MCTs.

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