title: Identification and characterization of HsIV HsIU (ClpQ ClpY) proteins involved in overall proteolysis of misfolded proteins in Escherichia coli.
abstract: Heat shock response in Escherichia coli is autoregulated. Consistent with this, mutations in certain heat shock genes, such as dnaK, dnaJ, grpE or htrC lead to a higher constitutive heat shock gene expression at low temperatures. A similar situation occurs upon accumulation of newly synthesized peptides released prematurely from the ribosomes by puromycin. We looked for gene(s) which, when present in multicopy, prevent the constitutive heat shock response associated with htrC mutant bacteria or caused by the presence of puromycin. One such locus was identified and shown to carry the recently sequenced hslV hslU (clpQ clpY) operon. HslV/ClpQ shares a very high degree of homology with members of the beta-type subunit, constituting the catalytic core of the 20S proteasome. HslU/ClpY is 50% identical to the ClpX protein of E. coli, which is known to present large polypeptides to its partner, the ATP-independent proteolytic enzyme ClpP. We show that, in vivo, HslV and HslU interact and participate in the degradation of abnormal puromycylpolypeptides. Biochemical evidence suggests that HslV/ClpQ is an efficient peptidase whose activity is enhanced by HslU/CIpY in the presence of ATP.
authors.affiliation: Centre National de Recherche Scientifique, LIDSM-CBBM, Marseille, France.
authors.forename: D
authors.initials: D
authors.lastname: Missiakas
authors.forename: F
authors.initials: F
authors.lastname: Schwager
authors.forename: J M
authors.initials: JM
authors.lastname: Betton
authors.forename: C
authors.initials: C
authors.lastname: Georgopoulos
authors.forename: S
authors.initials: S
authors.lastname: Raina
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D003208:Concanavalin A / Q000494:pharmacology; D004352:Drug Resistance, Microbial / Q000235:genetics; D049071:Endopeptidase Clp; D010450:Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D009876:Operon; D017510:Protein Folding; D011691:Puromycin / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012697:Serine Endopeptidases
chemical_list: C483566:ClpYQ protease, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; D003208:Concanavalin A; D011691:Puromycin; D010450:Endopeptidases; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases