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	D Missiakas, F Schwager, J M Betton, C Georgopoulos, S Raina
Journal	The EMBO journal (EMBO J) Vol. 15 Issue 24 Pg. 6899-909 (Dec 16 1996) ISSN: 0261-4189 [Print] England
PMID	9003766 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References	ClpYQ protease, E coli Escherichia coli Proteins Heat-Shock Proteins Recombinant Proteins Concanavalin A Puromycin Endopeptidases ATP-Dependent Proteases Serine Endopeptidases Endopeptidase Clp Adenosine Triphosphatases
Topics	ATP-Dependent Proteases Adenosine Triphosphatases (genetics, isolation & purification, metabolism) Cloning, Molecular Concanavalin A (pharmacology) Drug Resistance, Microbial (genetics) Endopeptidase Clp Endopeptidases (genetics, isolation & purification, metabolism) Escherichia coli (genetics, metabolism) Escherichia coli Proteins Heat-Shock Proteins (genetics, metabolism) Hydrolysis Operon Protein Folding Puromycin (pharmacology) Recombinant Proteins (genetics, isolation & purification, metabolism) Serine Endopeptidases

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