Bacteriophage Mu Repressor as a Target for the Escherichia Coli ATP-dependent Clp Protease

EMBO J. 1996 Jan 15;15(2):437-44.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / metabolism*
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Bacteriophage mu / genetics
  • Bacteriophage mu / metabolism*
  • Base Sequence
  • Binding Sites
  • Endopeptidase Clp
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli Proteins*
  • Genotype
  • Lysogeny
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plasmids
  • Point Mutation
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins / chemistry
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Sequence Homology, Amino Acid
  • Serine Endopeptidases / metabolism*
  • Substrate Specificity
  • Virulence Factors*


  • Bacterial Proteins
  • Escherichia coli Proteins
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Virulence Factors
  • Serine Endopeptidases
  • ClpXP protease, E coli
  • Endopeptidase Clp
  • Adenosine Triphosphatases