title: ClpE from Lactococcus lactis promotes repression of CtsR-dependent gene expression.
abstract: The heat shock response in bacterial cells is characterized by rapid induction of heat shock protein expression, followed by an adaptation period during which heat shock protein synthesis decreases to a new steady-state level. In this study we found that after a shift to a high temperature the Clp ATPase (ClpE) in Lactococcus lactis is required for such a decrease in expression of a gene negatively regulated by the heat shock regulator (CtsR). Northern blot analysis showed that while a shift to a high temperature in wild-type cells resulted in a temporal increase followed by a decrease in expression of clpP encoding the proteolytic component of the Clp protease complex, this decrease was delayed in the absence of ClpE. Site-directed mutagenesis of the zinc-binding motif conserved in ClpE ATPases interfered with the ability to repress CtsR-dependent expression. Quantification of ClpE by Western blot analysis revealed that at a high temperature ClpE is subjected to ClpP-dependent processing and that disruption of the zinc finger domain renders ClpE more susceptible. Interestingly, this domain resembles the N-terminal region of McsA, which was recently reported to interact with the CtsR homologue in Bacillus subtilis. Thus, our data point to a regulatory role of ClpE in turning off clpP gene expression following temporal heat shock induction, and we propose that this effect is mediated through CtsR.
authors.affiliation: Department of Dairy and Food Science, The Royal Veterinary and Agricultural University, DK-1958 Frederiksberg C, Denmark. pekka.varmanen@helsinki.fi
authors.forename: Pekka
authors.initials: P
authors.lastname: Varmanen
authors.forename: Finn K
authors.initials: FK
authors.lastname: Vogensen
authors.forename: Karin
authors.initials: K
authors.lastname: Hammer
authors.forename: Airi
authors.initials: A
authors.lastname: Palva
authors.forename: Hanne
authors.initials: H
authors.lastname: Ingmer
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D049071:Endopeptidase Clp; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D006358:Hot Temperature; D013294:Lactococcus lactis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C118338:CtsR protein, bacteria; D006360:Heat-Shock Proteins; D012097:Repressor Proteins; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C118340:ClpE protein, bacteria