Nonnative proteins induce expression of the Bacillus subtilis CIRCE regulon.
The chaperone-encoding groESL and dnaK operons constitute the CIRCE regulon of Bacillus subtilis. Both operons are under negative control of the repressor protein HrcA, which interacts with the CIRCE operator and whose activity is modulated by the GroESL chaperone machine. In this report, we demonstrate that induction of the CIRCE regulon can also be accomplished by ethanol stress and puromycin. Introduction of the hrcA gene and a transcriptional fusion under the control of the CIRCE operator into Escherichia coli allowed induction of this fusion by heat shock, ethanol stress, and overproduction of GroESL substrates. The expression level of this hrcA-bgaB fusion inversely correlated with the amount of GroE machinery present in the cells. Therefore, all inducing conditions seem to lead to induction via titration of the GroE chaperonins by the increased level of nonnative proteins formed. Puromycin treatment failed to induce the sigmaB-dependent general stress regulon, indicating that nonnative proteins in general do not trigger this response. Reconstitution of HrcA-dependent heat shock regulation of B. subtilis in E. coli and complementation of E. coli groESL mutants by B. subtilis groESL indicate that the GroE chaperonin systems of the two bacterial species are functionally exchangeable.
Mogk
A
A
Institut für Genetik, Universität Bayreuth, 95440 Bayreuth, Germany.
Völker
A
A
Engelmann
S
S
Hecker
M
M
Schumann
W
W
Völker
U
U
D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D018833:Chaperonins / Q000235:genetics; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D000431:Ethanol / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D018869:Heat-Shock Response; D002479:Inclusion Bodies; D018832:Molecular Chaperones / Q000235:genetics*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins; D018085:Regulon / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics; D012808:Sigma Factor / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C097970:GroESL protein, Bacteria; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D000431:Ethanol; D012965:Sodium Chloride; D018833:Chaperonins; C063842:dnaK protein, E coli