Section 45
Chapter 44,799

Thermal regulation of membrane fluidity in Escherichia coli. Effects of overproduction of beta-ketoacyl-acyl carrier protein synthase i

De Mendoza, D.; Klages Ulrich, A.; Cronan, J.E.

Journal of Biological Chemistry 258(4): 2098-2101


ISSN/ISBN: 0021-9258
PMID: 6337151
Accession: 044798718

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.

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