Affiliation:
1. Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105,1 and
2. Department of Biochemistry, University of Tennessee, Memphis, Tennessee 381632
Abstract
ABSTRACT
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 β-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-branched-chain 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.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
229 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献