title: The sigma S level in starving Escherichia coli cells increases solely as a result of its increased stability, despite decreased synthesis.
abstract: The sigma S level in starving (stationary phase) Escherichia coli cells increases four-to sixfold following growth in a defined or a complex medium. Chemostat-grown cells, subjected to increasing carbon starvation, also become progressively richer in sigma S content. These increases occur despite reduced transcription of the sigma S-encoding gene, rpoS, and translation of rpoS mRNA, and result solely from a large increase in the stability of the sigma protein. Previous results, based on rpoS::lacZ transcriptional and translational fusions, and on methionine incorporation in sigma S, had suggested increased synthesis of sigma S in starving cells. Alternative explanations for these results consistent with the conclusions of this paper are discussed.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Stanford University, California 94305, USA.
authors.forename: H I
authors.initials: HI
authors.lastname: Zgurskaya
authors.forename: M
authors.initials: M
authors.lastname: Keyhan
authors.forename: A
authors.initials: A
authors.lastname: Matin
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004355:Drug Stability; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005798:Genes, Bacterial; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D007399:Interphase; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D006159:Guanosine Tetraphosphate