Divergent roles of RpoS in Escherichia coli under aerobic and anaerobic conditions.
Escherichia coli exhibited different levels of rpoS expression and general stress resistance under aerobiosis and anaerobiosis. Expression measured using reporter gene fusions and protein levels was lower under anaerobic conditions. Consistent with earlier findings, rpoS mutants were selected in aerobic nutrient-limited cultures but rpoS mutants were not enriched under anaerobiosis. This result suggested that, despite its decreased level, RpoS had a function under anaerobic conditions not essential under aerobiosis. Competition experiments between rpoS(+) and rpoS bacteria confirmed the advantage conferred by RpoS under anaerobiosis. In contrast, stress resistance assays suggested RpoS made a greater contribution to general stress resistance under aerobiosis than anaerobiosis. These results indicate a significant, but different role of RpoS in aerobic and anaerobic environments.
King
Thea
T
School of Molecular and Microbial Biosciences G08, University of Sydney, Sydney, NSW 2006, Australia.
Ferenci
Thomas
T
D000332:Aerobiosis / Q000502:physiology; D000693:Anaerobiosis / Q000502:physiology; D001426:Bacterial Proteins / Q000502:physiology*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D012808:Sigma Factor / Q000502:physiology*
D001426:Bacterial Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria