Regulation of Escherichia coli starvation sigma factor (sigma s) by ClpXP protease.
In Escherichia coli, starvation (stationary-phase)-mediated differentiation involves 50 or more genes and is triggered by an increase in cellular sigma s levels. Western immunoblot analysis showed that in mutants lacking the protease ClpP or its cognate ATPase-containing subunit ClpX, sigma s levels of exponential-phase cells increased to those of stationary-phase wild-type cells. Lack of other potential partners of ClpP, i.e., ClpA or ClpB, or of Lon protease had no effect. In ClpXP-proficient cells, the stability of sigma s increased markedly in stationary-phase compared with exponential-phase cells, but in ClpP-deficient cells, sigma s became virtually completely stable in both phases. There was no decrease in ClpXP levels in stationary-phase wild-type cells. Thus, sigma s probably becomes more resistant to this protease in stationary phase. The reported sigma s-stabilizing effect of the hns mutation also was not due to decreased protease levels. Studies with translational fusions containing different lengths of sigma s coding region suggest that amino acid residues 173 to 188 of this sigma factor may directly or indirectly serve as at least part of the target for ClpXP protease.
Schweder
T
T
Department of Microbiology & Immunology, Stanford University, School of Medicine, California 94305-5402, USA.
Lee
K H
KH
Lomovskaya
O
O
Matin
A
A
D049069:ATP-Dependent Proteases; D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000502:physiology; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D049070:Protease La; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012697:Serine Endopeptidases / Q000235:genetics / Q000502:physiology*; D012808:Sigma Factor / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D001616:beta-Galactosidase; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483568:ClpA protease, E coli; C483567:Lon protein, E coli; D049070:Protease La; C483573:ClpXP protease, E coli; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities