Open AccessRpoS, H‐NS, and DsrA influence EHEC hemolysin operon ( ehxCABD ) transcription in Escherichia coli O157:H7 strain EDL933
Author(s) -
Li Haiping,
Granat Anastasiya,
Stewart Valley,
Gillespie Jerry R.
Publication year - 2008
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.1574-6968.2008.01240.x
Subject(s) - rpos , operon , sigma factor , transcription (linguistics) , biology , escherichia coli , mutant , microbiology and biotechnology , promoter , hemolysin , transcription factor , wild type , virulence , genetics , gene , gene expression , linguistics , philosophy
Escherichia coli hemolysin, also termed α‐hemolysin, is a virulence factor for extraintestinal E. coli . Hemolysin operon ( hlyCABD ) transcription is inhibited by the nucleoid‐associated protein, H‐NS. This inhibition is stronger at lower growth temperature. This study investigated transcription of the homologous EHEC hemolysin (enterohemolysin) operon ( ehxCABD ) in EHEC O157:H7 strain EDL933. We examined the influence of H‐NS, the σ factor RpoS, and the small RNA DsrA, which is known to inhibit H‐NS function and to stimulate RpoS synthesis. During growth at 30 °C, DsrA overexpression increased ehxA transcription in the wild type but not in an hns deletion mutant. During growth at 37 °C, DsrA overexpression increased ehxA transcription independent of hns genotype. This indicates that DsrA influences ehxCABD operon transcription by two different routes, one (at lower temperature) at least partially dependent on H‐NS, and one (at higher temperature) independent of H‐NS. An rpoS deletion mutant expressed nondetectable levels of ehxA mRNA regardless of growth temperature or DsrA overexpression, indicating that the RpoS σ factor is essential for ehxCABD operon expression.