Open AccessTwo highly related regulatory proteins, Shigella flexneri VirF and enterotoxigenic Escherichia coli Rns, have common and distinct regulatory properties
Author(s) -
Porter Megan E,
Smith Stephen G.J,
Dorman Charles J
Publication year - 1998
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1998.tb13013.x
Subject(s) - shigella flexneri , regulon , biology , enterotoxigenic escherichia coli , regulator gene , gene , genetics , transcription factor , regulation of gene expression , promoter , activator (genetics) , escherichia coli , microbiology and biotechnology , gene expression , enterotoxin
The Rns protein of enterotoxigenic Escherichia coli (ETEC) and the VirF protein of Shigella flexneri are members of the AraC family of transcription regulators. Rns is required for positive activation of the CS1 fimbrial genes, while VirF is a positive regulator of an invasion gene regulon. The amino acid sequences of the proteins are 36% identical, and both proteins activate transcription in response to increases in temperature. Here, we show that Rns is capable of complementing fully a null mutation in the S. flexneri virF gene. However, the VirF protein cannot replace Rns as an activator of CS1 gene expression in ETEC. This failure is not due to the absence from ETEC of a co‐factor required by VirF since it also occurs when the CS1 system is moved into an S. flexneri genetic background. Nor is it a function of growth medium composition or a failure in virF gene expression. Instead, these findings point to important differences in the mechanisms by which these related transcription factors regulate gene expression in Gram‐negative pathogens.