Biosynthesis of Branched-Chain Fatty Acids: Iv. Factors Affecting Relative Abundance of Fatty Acids Produced by Bacillus Subtilis

Kaneda, Toshi

doi:10.1139/m66-073

Cited by 85 publications

(67 citation statements)

References 19 publications

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“…The addition of exogenous leucine or valine to cultures of S. glaucescens resulted in a concomitant increase in the relevant branched-chain fatty acid derived from these precursors (29). It was noted previously that the largest component of the branched-chain fatty acid profile was related to the relative size of metabolic pools of ␣-ketoisocaproate, ␣-keto-␤-methylvalerate, and ␣-ketoisovalerate (17,20). These ␣-keto acids are present at much lower intracellular concentrations than the corresponding amino acids in E. coli, due to the high affinities of the transaminases for the ␣-keto acids compared to the corresponding amino acids (32).…”

Section: Discussionmentioning

confidence: 91%

β-Ketoacyl-Acyl Carrier Protein Synthase III (FabH) Is a Determining Factor in Branched-Chain Fatty Acid Biosynthesis

2000

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A universal set of genes encodes the components of the dissociated, type II, fatty acid synthase system that is responsible for producing the multitude of fatty acid structures found in bacterial membranes. We examined the biochemical basis for the production of branched-chain fatty acids by gram-positive bacteria. Two genes that were predicted to encode homologs of the ␤-ketoacyl-acyl carrier protein synthase III of Escherichia coli (eFabH) were identified in the Bacillus subtilis genome. Their protein products were expressed, purified, and biochemically characterized. Both B. subtilis FabH homologs, bFabH1 and bFabH2, carried out the initial condensation reaction of fatty acid biosynthesis with acetyl-coenzyme A (acetyl-CoA) as a primer, although they possessed lower specific activities than eFabH. bFabH1 and bFabH2 also utilized iso-and anteiso-branchedchain acyl-CoA primers as substrates. eFabH was not able to accept these CoA thioesters. Reconstitution of a complete round of fatty acid synthesis in vitro with purified E. coli proteins showed that eFabH was the only E. coli enzyme incapable of using branched-chain substrates. Expression of either bFabH1 or bFabH2 in E. coli resulted in the appearance of a branched-chain 17-carbon fatty acid. Thus, the substrate specificity of FabH is an important determinant of branched-chain fatty acid production.

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Section: Discussionmentioning

confidence: 91%

β-Ketoacyl-Acyl Carrier Protein Synthase III (FabH) Is a Determining Factor in Branched-Chain Fatty Acid Biosynthesis

2000

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“…Therefore, we still have no idea as to how bacteria regulate BCFA to fulfill different requirements. There are studies showing that exogenous BCAA can largely influence the fatty acid profiles in some bacteria (25,55). However, the molecular mechanism for this phenomenon has not been revealed.…”

Section: Discussionmentioning

confidence: 99%

Role and Regulation of Fatty Acid Biosynthesis in the Response of Shewanella piezotolerans WP3 to Different Temperatures and Pressures

et al. 2009

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Members of the genus Shewanella inhabit various environments; they are capable of synthesizing various types of low-melting-point fatty acids, including monounsaturated fatty acids (MUFA) and branched-chain fatty acids (BCFA) with and without eicosapentanoic acid (EPA). The genes involved in fatty acid synthesis in 15 whole-genome-sequenced Shewanella strains were identified and compared. A typical type II fatty acid synthesis pathway in Shewanella was constructed. A complete EPA synthesis gene cluster was found in all of the Shewanella genomes, although only a few of them were found to produce EPA. The roles and regulation of fatty acids synthesis in Shewanella were further elucidated in the Shewanella piezotolerans WP3 response to different temperatures and pressures. The EPA and BCFA contents of WP3 significantly increased when it was grown at low temperature and/or under high pressure. EPA, but not MUFA, was determined to be crucial for its growth at low temperature and high pressure. A gene cluster for a branched-chain amino acid ABC transporter (LIV-I) was found to be upregulated at low temperature. Combined approaches, including mutagenesis and an isotopic-tracer method, revealed that the LIV-I transporter played an important role in the regulation of BCFA synthesis in WP3. The LIV-I transporter was identified only in the cold-adapted Shewanella species and was assumed to supply an important strategy for Shewanella cold adaptation. This is the first time the molecular mechanism of BCFA regulation in bacteria has been elucidated.

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“…To reduce octylglucoside, samples were extensively dialyzed (60 h at 4°C) against deionized water. Coextracted lipopolysaccharide (LPS) and phospholipids were estimated after alkaline hydrolysis (22). The released fatty acids were converted to the corresponding methylesters by diazomethane (29) Fig.…”

Section: Methodsmentioning

confidence: 99%

Preparation of the FhuA (TonA) receptor protein from cell envelopes of an overproducing strain of Escherichia coli K-12

Hoffmann¹,

Fischer²,

Kraut³

et al. 1986

J Bacteriol

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A rapid and simple method for purification of the FhuA receptor protein from cell envelopes of a FhuA-overproducing strain of Escherichia coli K-12 was developed. The overproduction of FhuA was programmed by the thermoamplifiable plasmid pHK232, which carried thefljuACD genes of pLC19-19 of the Clarke and Carbon collection. At low temperature (27°C), pHK232 specified the overproduction of FhuA to levels comparable to those of major outer membrane proteins OmpF, OmpC, and OmpA. The amount of these proteins in the outer membrane was reduced along with overproduction of FhuA. Upon runaway replication of pHK232 at 37C, the precursor of the FhuA protein, proFhuA, was also accumulated in the cell envelope in amounts similar to FhuA. For extraction of the FhuA protein, crude cell envelopes were washed with 2% Triton X-100-6 M urea to remove less tightly bound proteins. Then FhuA but not proFhuA was solubilized by treating Triton X-100-urea-washed membranes with 1% octylglucoside-1 mM EDTA. This procedure yielded FhuA protein free from other membrane proteins. The amount of lipopolysaccharide and phospholipids was low and ranged from 5 to 15% and 10 to 25% of the weight of the FhuA protein, respectively. As shown by direct inactivation and by competition assays, the isolated FhuA protein retained receptor activity for ferrichrome, albomycin, colicin M, and phages T5 and Ti.The protein specified by the JhuA gene is a minor protein (approximately 103 copies per cell) of the outer membrane of Escherichia coli, with an apparent molecular weight of 78,000 (78K). It is a component of the transport system for the siderophores ferrichrome and albomycin, and it serves as a receptor for colicin M and for the phages T5, Ti and 4)80 (3,18). With the exception of the receptor function for phage T5, receptor activity of FhuA is linked to and may be modified by interaction with other proteins. The uptake of ferrichrome and albomycin depends on functions encoded by additional genes of the fhu operon (21), JfhuC, JhuD, and JhuB (13), and functions specified by the genes tonB (9) and exbB (19). Infection by phages Ti and 480 requiresfiiuA and tonB (14), while sensitivity to colicin M requiresfjzuA, tonB, and exbB (27). The molecular mechanisms underlying the different receptor functions of FhuA are unknown.

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Biosynthesis of Branched-Chain Fatty Acids: Iv. Factors Affecting Relative Abundance of Fatty Acids Produced by Bacillus Subtilis

Cited by 85 publications

References 19 publications

β-Ketoacyl-Acyl Carrier Protein Synthase III (FabH) Is a Determining Factor in Branched-Chain Fatty Acid Biosynthesis

β-Ketoacyl-Acyl Carrier Protein Synthase III (FabH) Is a Determining Factor in Branched-Chain Fatty Acid Biosynthesis

Role and Regulation of Fatty Acid Biosynthesis in the Response of Shewanella piezotolerans WP3 to Different Temperatures and Pressures

Preparation of the FhuA (TonA) receptor protein from cell envelopes of an overproducing strain of Escherichia coli K-12

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