title: DNA binding by the coliphage 186 repressor protein CI.
abstract: The cI gene of coliphage 186 maintains lysogeny and confers immunity to 186 infection by repressing the major early promoter, p(R), and the promoter for the late transcription activator gene, p(B).  Gel mobility shirt and DNase I footprinting show that CI protein binds to the DNA at p(R) and p(B) and also to sites approximately 300 base pairs upstream and downstream of p(R), called FL and FR. Mutations which cause virulence reduce CI binding to p(R). The biochemical and genetic data identify three CI operators at p(R), two at p(B), and single operators at FL and FR.  The operators at the p(B), FL, FR, and central p(R) sites are inverted repeat sequences, separated by 5 base pairs (Type A) or, in the case of p(R), by 4 base pairs (Type A').  A different inverted repeat operator sequence (Type B) is proposed for the binding sites on each side of the central site at p(R).  Thus, CI appears to recognize two distinct DNA sequences.  CI binds cooperatively to adjacent operators, and binding at p(R) is strongly dependent on these cooperative interactions.  A high order CI multimer appears to be the active DNA binding species, even at single operators.
authors.affiliation: Department of Biochemistry, University of Adelaide, Australia.
authors.forename: I B
authors.initials: IB
authors.lastname: Dodd
authors.forename: J B
authors.initials: JB
authors.lastname: Egan
mesh_terms: D000595:Amino Acid Sequence; D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites; D003090:Coliphages / Q000235:genetics / Q000378:metabolism*; D016384:Consensus Sequence; D018983:DNA Footprinting; D017931:DNA Primers; D004268:DNA-Binding Proteins; D003850:Deoxyribonuclease I; D004926:Escherichia coli; D005800:Genes, Fungal; D007700:Kinetics; D008242:Lysogeny; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000378:metabolism*; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D003850:Deoxyribonuclease I