title: The CtsR regulator of stress response is active as a dimer and specifically degraded in vivo at 37 degrees C.
abstract: CtsR (class three stress gene repressor) negatively regulates the expression of class III heat shock genes (clpP, clpE and the clpC operon) by binding to a directly repeated heptanucleotide operator sequence (A/GGTCAAA NAN A/GGTCAAA). CtsR-dependent genes are expressed at a low level at 37 degrees C and are strongly induced under heat shock conditions. We performed a structure/function analysis of the CtsR protein, which is highly conserved among low G+C Gram-positive bacteria. Random chemical mutagenesis, in vitro cross-linking, in vivo co-expression of wild-type and mutant forms of CtsR and the construction of chimeric proteins with the DNA-binding domain of the lambda CI repressor allowed us to identify three different functional domains within CtsR: a helix-turn-helix DNA-binding domain, a dimerization domain and a putative heat-sensing domain. We provide evidence suggesting that CtsR is active as a dimer. Transcriptional analysis of a clpP'-bgaB fusion and/or Western blotting experiments using antibodies directed against the CtsR protein indicate that ClpP and ClpX are involved in CtsR degradation at 37 degrees C. This in turn leads to a low steady-state level of CtsR within the cell, as CtsR negatively autoregulates its own synthesis. This is the first example of degradation of a repressor of stress response genes by the Clp ATP-dependent protease.
authors.affiliation: Unité de Biochimie Microbienne, URA 2172 du Centre National de la Recherche Scientifique, Institut Pasteur, 25, rue du Docteur Roux, 75724 Paris Cedex 15, France. iderre@pasteur.fr
authors.forename: I
authors.initials: I
authors.lastname: Derré
authors.forename: G
authors.initials: G
authors.lastname: Rapoport
authors.forename: T
authors.initials: T
authors.lastname: Msadek
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D019281:Dimerization; D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005998:Glycine / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D019077:Helix-Turn-Helix Motifs; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; C087481:ClpC protein, Bacteria; C118338:CtsR protein, bacteria; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D012097:Repressor Proteins; D004247:DNA; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities; D005998:Glycine