Premium
Identification of regulatory factors of the stationary phase sigma factor RpoS in Escherichia coli
Author(s) -
Nguyen Kien,
Peterson Celeste
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1031.18
Subject(s) - rpos , sigma factor , plasmid , biology , lac operon , gene , transcription (linguistics) , reporter gene , gene expression , escherichia coli , genetics , rna polymerase , microbiology and biotechnology , promoter , linguistics , philosophy
The sigma factor RpoS is the master regulator of the general stress response that helps cells survive harsh environmental conditions by associating with the RNA polymerase and regulating gene expression. While numerous stresses are known to up‐regulate RpoS, many of the molecular steps leading from stresses to changes in RpoS levels remain unknown. To screen for the novel regulators, we used an RpoS’‐‘LacZ fusion. We transformed the reporter strains with an overexpression library, screening for plasmids that resulted in colonies with either more or less RpoS as observed on Xgal indicator plates. We verified that RpoS levels were altered in the presence of the plasmid with Western blots and quantified the effect on RpoS expression beta‐galactosidase assays in both RpoS transcription and translation lacZ fusions. We identified the genes on the plasmids as gadY, rbsD, yhhI, yhjR, ykgR and part of the dsdA gene in the screen. Our results suggested all of the factors, with the exception of rbsD, regulated RpoS in a post‐transcriptional manner either at the level of translation or protein stability. The small RNA gadY caused a strong inhibitory effect on RpoS expression and yhhI, ykgR and yhjR causing a mild increase expression of RpoS. In summary, we have found multiple new factors that affect RpoS at the post‐transcriptional level.