title: Homology-dependent interactions in phage lambda site-specific recombination.
abstract: General recombination shows a dependence on large regions of homology between the two participating segments of DNA. Many site-specific recombination systems also exhibit a dependence on homology, although in these systems the requirement is limited to a short region (less than 10 base pairs (bp]. We have used the in vitro phage lambda integration reaction to study the role of homology in this model site-specific recombination system. We find that certain non-homologous pairings which are strongly blocked for complete recombination, nevertheless make one pair of strand-exchanges to generate a joint molecule of the Holliday structure type. This result rules out recombination models in which the only homology-dependent step is synapsis (the juxtaposing of the two recombination sites). Our results also reveal a functional asymmetry in the recombination sites. We present models for bacteriophage lambda integrative recombination which accommodate these findings.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D008954:Models, Biological; D009154:Mutation; D009692:Nucleic Acid Heteroduplexes; D010957:Plasmids; D011995:Recombination, Genetic; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D009692:Nucleic Acid Heteroduplexes