title: Thermal regulation of membrane fluidity in Escherichia coli. Effects of overproduction of beta-ketoacyl-acyl carrier protein synthase I.
abstract: Multicopy plasmids bearing the structural gene (fabB) for beta-ketoacyl-acyl carrier protein (ACP) synthase I were constructed in vitro and transformed into various Escherichia coli strains. Introduction of these plasmids into fabB strains resulted in a fabB+ phenotype and a large (8- to 10-fold) overproduction of synthase I activity. Strains carrying these plasmids were also unusually resistant to cerulenin (an antibiotic that specifically inhibits beta-ketoacyl-ACP synthase activity) and overproduced cis-vaccenic acid. Strains (fabF-) lacking beta-ketoacyl-ACP synthase II are deficient in both cis-vaccenic acid synthesis and thermal regulation. Introduction of the fabB plasmids into these strains resulted in the restoration of cis-vaccenic acid synthesis. However, the plasmid-engendered cis-vaccenic acid synthesis of these strains was unaffected by temperature. These results demonstrate that synthase II, the product of the fabF gene, is the sole enzyme regulating the temperature-dependent composition of the membrane phospholipid acyl chains.
mesh_terms: D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase / Q000096:biosynthesis* / Q000235:genetics; D000217:Acyltransferases / Q000096:biosynthesis*; D002569:Cerulenin / Q000494:pharmacology; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005227:Fatty Acids / Q000032:analysis; D005796:Genes; D006358:Hot Temperature; D008560:Membrane Fluidity; D010957:Plasmids
chemical_list: D005227:Fatty Acids; D002569:Cerulenin; D000217:Acyltransferases; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase