title: ClpX, an alternative subunit for the ATP-dependent Clp protease of Escherichia coli. Sequence and in vivo activities.
abstract: The ATP-dependent Clp protease of Escherichia coli consists of two subunits, the ClpP subunit, which has the proteolytic active site, and ClpA, which possesses ATPase activity and activates the proteolytic activity of ClpP in vitro. Recently, Zylicz and co-workers (Wojtkowiak, D., Georgopoulos, C., and Zylicz, M. (1993) J. Biol. Chem. 268, 22609-22617) identified another E. coli protein that activated ATP-dependent degradation of lambda O protein in the presence of ClpP. The amino-terminal sequence of this protein corresponds to the translated amino-terminal sequence of a gene that we have named clpX. clpX encodes a protein with M(r) 46,300, similar to that observed for the protein purified by Wojtkowiak et al. clpX is an operon with clpP; both genes are cotranscribed in a single heat-inducible 2200-base mRNA, with clpP the promoter proximal gene. The sequence of ClpX includes a single consensus ATP-binding site motif and has limited homology to regions of ClpA and other members of the ClpA/B/C family. A third group of proteins, ClpY, closely related to ClpX, has been identified by sequence homology. Mutations in either clpX or clpP abolish degradation of the highly unstable lambda O protein in vivo. clpX mutants are not defective in degradation of previously identified ClpA/ClpP substrates such as a ClpA-beta-galactosidase fusion protein. It appears that selectivity of degradation by ClpP in vivo is determined by interaction of ClpP with different regulatory ATPase subunits.
authors.affiliation: Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892.
authors.forename: S
authors.initials: S
authors.lastname: Gottesman
authors.forename: W P
authors.initials: WP
authors.lastname: Clark
authors.forename: V
authors.initials: V
authors.lastname: de Crecy-Lagard
authors.forename: M R
authors.initials: MR
authors.lastname: Maurizi
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000378:metabolism; D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D016384:Consensus Sequence; D004261:DNA Replication; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D005838:Genotype; D006360:Heat-Shock Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism
chemical_list: C483566:ClpYQ protease, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; C027812:O protein, Bacteriophage lambda; D014764:Viral Proteins; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases