title: Stereoselectivity in the 2-methylbutyrate incorporation into anteiso fatty acids in Bacillus subtilis mutants.
abstract: Two Bacillus subtilis mutants defective in branched-chain alpha-ketoacid dehydrogenase can grow when 2-methylbutyrate is provided in trypticase soy medium. Both enantiomers of the acid supported growth of the mutants but the (S)-(+)-isomer (natural) was more active than the (R)-(-)-isomer (unnatural). The mutants utilized these isomers as primer to specifically synthesize either enantiomer of anteiso fatty acids. No racemization of the isomer primers was observed during the synthesis. Thus, cells grown with (-)-isomer possessed anteiso fatty acids (over 80%) of the total fatty acids, being entirely the unnatural enantiomer. The stereospecific synthesis was found to be controlled at the step of 2-methylbutyryl-CoA synthesis. In a wild strain, only (+)-specific acyl-CoA synthetase was detected. In the mutants, either enantiomer of 2-methylbutyrate could simultaneously induce both types, (+)-specific and (-)-specific, of acyl-CoA synthetase. (+)-Specific synthetase had a higher activity and affinity towards substrate than (-)-specific synthetase. The detailed preparative procedures for (R)-(-)- and 2-[3,4-3H]methylbutyric acid are described.
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D001412:Bacillus subtilis / Q000201:enzymology / Q000378:metabolism*; D002087:Butyrates / Q000494:pharmacology*; D003066:Coenzyme A Ligases / Q000032:analysis / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis*; D007658:Ketone Oxidoreductases / Q000172:deficiency; D008563:Membrane Lipids / Q000096:biosynthesis; D009097:Multienzyme Complexes / Q000172:deficiency; D009154:Mutation; D010169:Palmitic Acids / Q000096:biosynthesis; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D013237:Stereoisomerism; D000098859:Long-Chain-Fatty-Acid-CoA Ligase
chemical_list: D002087:Butyrates; D005227:Fatty Acids; D008563:Membrane Lipids; D009097:Multienzyme Complexes; D010169:Palmitic Acids; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C055720:12-methylhexadecanoic acid; C046143:14-methylhexadecanoic acid; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D003066:Coenzyme A Ligases; C090799:FAA2 protein, S cerevisiae; D000098859:Long-Chain-Fatty-Acid-CoA Ligase; C019475:2-methylbutanoic acid