title: Characterization of the cts4 repressor mutation in transposable bacteriophage Mu.
abstract: Mucts4 was isolated more than 30 years ago and was the first available thermoinducible derivative of transposable phage Mu. We have characterized the cts4 mutation and the corresponding mutant protein. Contrary to previously characterized thermoinducible Mu prophages (e.g., Mucts62), Mucts4 lysogenizes at reduced frequency even at 30 degrees C. The cts4 mutation (Leu129Val) was located in this central repressor region. The cts4 protein was thermosensitive for operator DNA binding in vitro. Temperature-dependent changes in protein-protein cross-linking patterns in the absence of DNA were detected for purified wild type, cts62 and cts4 repressor proteins. The cts4 protein exhibited a subtly different electrophoretic profile, which became more marked at higher temperatures, from both the wild type and cts62. In addition the cts4 repressor generated a significantly different pattern of binding to DNA fragments carrying the early operator region. Consistent with the predicted involvement of the central leucine-rich region of the Mu repressor in the formation of multimeric forms, the cts4 mutation thus appeared to affect protein-protein interactions.
authors.affiliation: Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS-université Toulouse III, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Rousseau
authors.forename: Jamal E
authors.initials: JE
authors.lastname: Laachouch
authors.forename: Mick
authors.initials: M
authors.lastname: Chandler
authors.forename: Ariane
authors.initials: A
authors.lastname: Toussaint
mesh_terms: D010583:Bacteriophage mu / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D016679:Genome, Viral; D016296:Mutagenesis; D009154:Mutation; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013696:Temperature; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins