title: Control of directionality in bacteriophage mv4 site-specific recombination: functional analysis of the Xis factor.
abstract: The integrase of the temperate bacteriophage mv4 catalyzes site-specific recombination between the phage attP site and the host attB site during Lactobacillus delbrueckii lysogenization. The mv4 prophage is excised during the induction of lytic growth. Excisive site-specific recombination between the attR and attL sites is also catalyzed by the phage-encoded recombinase, but the directionality of the recombination is determined by a second phage-encoded protein, the recombination directionality factor (RDF). We have identified and functionally characterized the RDF involved in site-specific excision of the prophage genome. The mv4 RDF, (mv4)Xis, is encoded by the second gene of the early lytic operon. It is a basic protein of 56 amino acids. Electrophoretic mobility shift assays demonstrated that (mv4)Xis binds specifically to the attP and attR sites via two DNA-binding sites, introducing a bend into the DNA. In vitro experiments and in vivo recombination assays with plasmids in Escherichia coli and Lactobacillus plantarum demonstrated that (mv4)Xis is absolutely required for inter- or intramolecular recombination between the attR and attL sites. In contrast to the well-known phage site-specific recombination systems, the integrative recombination between the attP and attB sites seems not to be inhibited by the presence of (mv4)Xis.
authors: Université de Toulouse, UPS, Laboratoire de Microbiologie et de Génétique Moléculaires, F-31000 Toulouse, France.
authors: Michèle
authors: M
authors: Coddeville
authors: Paul
authors: P
authors: Ritzenthaler
mesh_terms: D001435:Bacteriophages / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D048668:Lactobacillus delbrueckii / Q000235:genetics* / Q000821:virology*; D008242:Lysogeny / Q000235:genetics; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D045522:Recombinases / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D016662:Virus Integration / Q000235:genetics*
chemical_list: D045522:Recombinases; D014764:Viral Proteins