Degradation of sigma 32, the heat shock regulator in Escherichia coli, is governed by HflB.
The heat shock response in Escherichia coli is governed by the concentration of the highly unstable sigma factor sigma 32. The essential protein HflB (FtsH), known to control proteolysis of the phage lambda cII protein, also governs sigma 32 degradation: an HflB-depleted strain accumulated sigma 32 and induced the heat shock response, and the half-life of sigma 32 increased by a factor up to 12 in mutants with reduced HflB function and decreased by a factor of 1.8 in a strain overexpressing HflB. The hflB gene is in the ftsJ-hflB operon, one promoter of which is positively regulated by heat shock and sigma 32. The lambda cIII protein, which stabilizes sigma 32 and lambda cII, appears to inhibit the HflB-governed protease. The E. coli HflB protein controls the stability of two master regulators, lambda cII and sigma 32, responsible for the lysis-lysogeny decision of phage lambda and the heat shock response of the host.
Herman
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Institut Jacques Monod, Centre National de la Recherche Scientifique, Université Paris, France.
Thévenet
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D'Ari
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Bouloc
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D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006207:Half-Life; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008242:Lysogeny / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014764:Viral Proteins
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D012808:Sigma Factor; D014157:Transcription Factors; D014764:Viral Proteins; C039000:cII protein, bacteriophage lambda; C054615:cIII protein, Bacteriophage lambda; C069774:heat-shock sigma factor 32; D010450:Endopeptidases; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli; D000251:Adenosine Triphosphatases