Open AccessEnhanced expression of the bgl operon of Escherichia coli in the stationary phase
Author(s) -
Madan Ranjna,
Moorthy Sudha,
Mahadevan Subramony
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.1574-6968.2008.01346.x
Subject(s) - rpos , operon , escherichia coli , transcription (linguistics) , stationary phase , wild type , biology , mutant , genetics , sigma factor , promoter , gene , allele , microbiology and biotechnology , gene expression , chemistry , linguistics , philosophy , chromatography , rna polymerase
The bgl operon is silent and uninducible in wild‐type strains of Escherichia coli and requires mutational activation for optimal expression. We show that transcription from the wild‐type and the activated bgl promoter exhibits a growth phase‐dependent enhancement that is highest in the stationary phase. We have assessed the effect of mutations in rpoS, crl, hns, leuO and bglJ , known to regulate bgl expression, on the growth phase‐dependent increase in bgl activity. These studies show that this increase is greater in the absence of wild‐type rpoS and/or crl . Our studies also indicate that while BglJ has a moderate effect on the expression of the bgl operon in the stationary phase in the absence of rpoS/crl , the modest increase in LeuO concentration in the stationary phase is insufficient to affect transcription from the bgl promoter. Measurements of the fitness of strains carrying the wild type or a null allele of crl showed that, while the strain deleted for crl exhibited a growth advantage over the crl + strain in an rpoS + background, it showed a low‐level disadvantage in the presence of an rpoS allele that results in attenuated RpoS expression. Possible physiological implications of these results are discussed.