title: Mutational analysis of integrase arm-type binding sites of bacteriophage lambda. Integration and excision involve distinct interactions of integrase with arm-type sites.
abstract: Integrative recombination between specific attachment (att) regions of the bacteriophage lambda genome (attP) and the Escherichia coli genome (attB) results in a prophage flanked by the hybrid recombinant sites attL and attR. Each att site contains sequences to which proteins involved in recombination bind. Using site-directed mutagenesis, we have constructed a related set of point mutations within each of the five Int "arm-type" binding sites located within attP, attL and attR. Footprint analyses of binding demonstrate that mutating the arm-type sites significantly disrupts the binding of Int. Recombination analyses of mutant att sites in vivo and in vitro demonstrate that only three wild-type arm-type sites within attP are required for efficient integrative recombination. Similar analyses demonstrate that efficient excision can occur with two other different sets of wild-type arm-type sites in attL and attR. These results demonstrate that integrative and excisive recombination may involve interactions of Int with distinct and different subsets of arm-type sites.
mesh_terms: D001287:Attachment Sites, Microbiological; D010582:Bacteriophage lambda / Q000235:genetics*; D001665:Binding Sites; D004254:DNA Nucleotidyltransferases / Q000235:genetics; D004279:DNA, Viral / Q000032:analysis; D004926:Escherichia coli / Q000235:genetics; D019426:Integrases; D008242:Lysogeny; D008957:Models, Genetic; D009154:Mutation; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000235:genetics
chemical_list: D004279:DNA, Viral; D014764:Viral Proteins; D004254:DNA Nucleotidyltransferases; D019426:Integrases