TolF locus in Escherichia coli: chromosomal location and relationship to loci cmlB and tolD

The relative amounts of the OmpF and OmpC proteins in the outer membrane of Escherichia coli K-12 are affected differentially by high concentrations of substances like sucrose in culture media in such a manner that a decrease in the amount of the OmpF protein appears to be compensated for by a reciprocal increase in the OmpC protein. When an ompF mutation was introduced, OmpC synthesis became almost independent of sucrose and occurred at the fully induced level even in the absence of sucrose. On the other hand, introduction of an ompC mutation did not affect the sucrose-dependent profile of OmpF synthesis. The effect of the ompF mutation was also examined with the ompC-lac fusion strain, in which expression of beta-galactosidase is under the control of the ompC promoter. The expression of beta-galactosidase coded for by the ompC-lac fusion in the ompF+ and ompF- strains was essentially the same as that of the OmpC protein, being sucrose dependent in the ompF+ strain and sucrose-independent in the ompF mutant. From these results we conclude that sucrose in the medium primarily regulates ompF gene expression, which in turn regulates ompC gene expression at the transcriptional level. This sequential regulatory mechanism is discussed in relation to the function of the ompB locus.

Section: Methodsmentioning

confidence: 99%

Regulation of outer membrane porin protein synthesis in Escherichia coli K-12: ompF regulates the expression of ompC

Ozawa¹,

Mizushima²

1983

“…These strains were grown in a rich medium (proteose peptone-beef extract medium) or in Vogel-Bonner minimal medium supplemented with 2 g of glucose per liter and appropriate levels of growth requirements. These media and growth conditions have been described previously (11).…”

Section: Methodsmentioning

confidence: 99%

“…The ompF gene (formerly called toiF) is the structural gene for the OmpF protein (32). The ompF gene is allelic with certain cmlB and cry mutants (11).…”

mentioning

confidence: 99%

Colicin A receptor: role of two Escherichia coli outer membrane proteins (OmpF protein and btuB gene product) and lipopolysaccharide

Chai¹,

Wu²,

Foulds³

1982

Self Cite

ompF cells were completely resistant to colicin A, whereas btuB cells were partially resistant. The OmpF protein, in the presence of added lipopolysaccharide, inactivated colicin A. This inactivation was enhanced by added btuB gene product. btuB gene product with lipopolysaccharide did not inactivate colicin A. These data, together with the observation that vitamin B12 protected btuB+ cells from the killing effect of colicin A, suggest that the colicin A receptor in Escherichia coli K-12 is composed of the OmpF protein, the btuB gene product, and lipopolysaccharide. 983 on July 31, 2020 by guest

“…At least three genetic loci determine the production of proteins la and lb. Strains carrying mutations in the par (meo) locus lack protein lb (2,29), and strains carrying mutations in the tolF-(also termed cmlB or cry) locus lack protein la (4,8). Strains with mutations in the ompB locus fail to produce either protein la or lb, as do strains carrying mutations in both par and tolF (9,12).…”

mentioning

confidence: 99%

Identification of three genes controlling production of new outer membrane pore proteins in Escherichia coli K-12

Pugsley¹,

Schnaitman²

1978

124

Escherichia coli K-12 strains carrying mutations in the ompB gene or double mutations in the tolF and par genes lack the major outer membrane proteins la and lb. These strains are deficient in the transport of small hydrophylic compounds and are multiply colicin resistant. When revertants of these strains were sought, a number of extragenic pseudorevertants were obtained which produced new outer membrane proteins. These new proteins could be divided into three classes by differences in electrophoretic mobility on polyacrylamide gels, by differing specificities for transport of small molecules, and by the identification of three different genetic loci for genes controlling their production. These genetic loci are designated as nmpA (at approximately 82.5 min on the E. coli K-12 genetic map), nmpB (8.6 min), and nmpC (12 min). The new proteins produced in strains carrying nmpA, nmpB, or nmpC mutations did not cross-react with antiserum against a mixture of proteins la and lb, or with antiserum against phage-directed protein 2. Production of the new membrane proteins restored sensitivity to some of the colicins. 1118 on July 31, 2020 by guest