Bacteriophage-Mu Repressor - a Target Protein for the Escherichia-Coli Atp-Dependent Clp Protease

J.E. Laachouch (1) , Lucie Desmet (1) , V. Geuskens (1) , Régis Grimaud (1, 2) , Ariane Toussaint (1, 2)

1 ULB - Université libre de Bruxelles
2 Laboratoire de Biochimie des Microorganismes

Bacteriophage Mu repressor, which is stable in its wild-type 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-erminal 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 exist- ence, on the substrate polypeptides, of separate motifs responsible for recognition and cleavage by the protease.

Mots clés: Clp protease; Lon protease; phage Mu; protease sensitivity; repressor

Domaines: Bactériologie; Biochimie, Biologie Moléculaire; Virologie

J.E. Laachouch, Lucie Desmet, V. Geuskens, Régis Grimaud, Ariane Toussaint. Bacteriophage-Mu Repressor - a Target Protein for the Escherichia-Coli Atp-Dependent Clp Protease. EMBO Journal, 1996, 15 (2), pp.437-444. ⟨10.1002/j.1460-2075.1996.tb00374.x⟩. ⟨hal-01152468⟩