Affiliation:
1. Departments of Microbiology1and
2. Biochemistry,2 University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Abstract
ABSTRACT
In
Escherichia coli
expression of the genes of fatty acid degradation (
fad
) is negatively regulated at the transcriptional level by FadR protein. In contrast the unsaturated fatty acid biosynthetic gene,
fabA
, is positively regulated by FadR. We report that
fabB
, a second unsaturated fatty acid biosynthetic gene, is also positively regulated by FadR. Genomic array studies that compared global transcriptional differences between wild-type and
fadR
-null mutant strains, as well as in cultures of each strain grown in the presence of exogenous oleic acid, indicated that expression of
fabB
was regulated in a manner very similar to that of
fabA
expression. A series of genetic and biochemical tests confirmed these observations. Strains containing both
fabB
and
fadR
mutant alleles were constructed and shown to exhibit synthetic lethal phenotypes, similar to those observed in
fabA fadR
mutants. A
fadR
strain was hypersensitive to cerulenin, an antibiotic that at low concentrations specifically targets the FabB protein. A transcriptional fusion of chloramphenicol acetyltransferase (CAT) to the
fabB
promoter produces lower levels of CAT protein in a strain lacking functional FadR. The ability of a putative FadR binding site within the
fabB
promoter to form a complex with purified FadR protein was determined by a gel mobility shift assay. These experiments demonstrate that expression of
fabB
is positively regulated by FadR.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
115 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