title: A comparative analysis of the bifunctional Cox proteins of two heteroimmune P2-like phages with different host integration sites.
abstract: The Cox protein of the coliphage P2 is multifunctional; it acts as a transcriptional repressor of the Pc promoter, as a transcriptional activator of the P(LL) promoter of satellite phage P4, and as a directionality factor for site-specific recombination. The Cox proteins constitute a unique group of directionality factors since they couple the developmental switch with the integration or excision of the phage genome. In this work, the DNA binding characteristics of the Cox protein of WPhi, a P2-related phage, are compared with those of P2 Cox. P2 Cox has been shown to recognize a 9 bp sequence, repeated at least 6 times in different targets. In contrast to P2 Cox, WPhi Cox binds with a strong affinity to the early control region that contains an imperfect direct repeat of 12 nucleotides. The removal of one of the repeats has drastic effects on the capacity of WPhi to bind to the Pe-Pc region. Again in contrast to P2 Cox, WPhi Cox has a lower affinity to attP compared to the Pe-Pc region, and a repeat of 9 bp can be found that has 5 bp in common with the repeat in the Pe-Pc region. WPhi Cox, however, is essential for excisive recombination in vitro. WPhi Cox, like P2 Cox, binds cooperatively with integrase to attP. Both Cox proteins induce a strong bend in their DNA targets upon binding.
authors.affiliation: Department of Genetics, Microbiology and Toxicology, Stockholm University, S-106 91 Stockholm.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Ahlgren-Berg
authors.forename: Carlos
authors.initials: C
authors.lastname: Cardoso-Palacios
authors.forename: Jesper M
authors.initials: JM
authors.lastname: Eriksson
authors.forename: Sridhar
authors.initials: S
authors.lastname: Mandali
authors.forename: Wilhelmina
authors.initials: W
authors.lastname: Sehlén
authors.forename: Lina
authors.initials: L
authors.lastname: Sylwan
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Haggård-Ljungquist
mesh_terms: D001287:Attachment Sites, Microbiological / Q000502:physiology; D017901:Bacteriophage P2 / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D016662:Virus Integration
chemical_list: C070354:Cox protein, Enterobacteria phage P2; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D014764:Viral Proteins