PMID:8550468
| Citation |
Schweder, T, Lee, KH, Lomovskaya, O and Matin, A (1996) Regulation of Escherichia coli starvation sigma factor (sigma s) by ClpXP protease. J. Bacteriol. 178:470-6 |
|---|---|
| Abstract |
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. |
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| Keywords |
ATP-Dependent Proteases; Adenosine Triphosphatases/genetics; Adenosine Triphosphatases/physiology; Bacterial Proteins/biosynthesis; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Sequence; DNA-Binding Proteins/genetics; Endopeptidase Clp; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli/physiology; Escherichia coli Proteins; Gene Expression Regulation, Bacterial/physiology; Heat-Shock Proteins/genetics; Heat-Shock Proteins/physiology; Molecular Chaperones; Molecular Sequence Data; Mutation; Nuclear Proteins/genetics; Protease La; Recombinant Fusion Proteins/biosynthesis; Serine Endopeptidases/genetics; Serine Endopeptidases/physiology; Sigma Factor/biosynthesis; Sigma Factor/genetics; Sigma Factor/metabolism; beta-Galactosidase/biosynthesis; beta-Galactosidase/genetics |
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