title: Bacteriophage Mu repressor as a target for the Escherichia coli ATP-dependent Clp Protease.
abstract: Bacteriophage Mu repressor, which is stable in its wildtype form, can mutate to become sensitive to its Escherichia coli host ATP-dependent ClpXP protease. We further investigated the determinants of the mutant repressor's sensitivity to Clp. We show the crucial importance of a C-terminal, seven amino acid long sequence in which a single change is sufficient to decrease the rate of degradation of the protein. The sequence was fused at the C-terminal end of the CcdB and CcdA proteins encoded by plasmid F. CcdB, which is naturally stable, was unaffected, while CcdA, which is normally degraded by the Lon protease, became a substrate for ClpXP while remaining a substrate for Lon. In agreement with the current hypothesis on the mechanism of recognition of their substrates by energy- dependent proteases, these results support the existence, on the substrate polypeptides, of separate motifs responsible for recognition and cleavage by the protease.
authors.affiliation: Laboratorie de Génétique des Procaryotes, Université Libre de Bruxelles, Genese, Belgium.
authors.forename: J E
authors.initials: JE
authors.lastname: Laachouch
authors.forename: L
authors.initials: L
authors.lastname: Desmet
authors.forename: V
authors.initials: V
authors.lastname: Geuskens
authors.forename: R
authors.initials: R
authors.lastname: Grimaud
authors.forename: A
authors.initials: A
authors.lastname: Toussaint
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D010583:Bacteriophage mu / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D049071:Endopeptidase Clp; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D005838:Genotype; D008242:Lysogeny; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D017354:Point Mutation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism*; D013379:Substrate Specificity; D037521:Virulence Factors
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D037521:Virulence Factors; D012697:Serine Endopeptidases; C483573:ClpXP protease, E coli; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases