title: Recombinant DNA molecules of bacteriophage phi chi174.
abstract: Phi chi174 DNA structures containing two different parental genomes were detected genetically and examined by electron microscopy. These structures consisted of two monomeric double-stranded DNA molecules linked in a figure 8 configuration. Such DNA structures were observed to be formed preferentially in host recA+ cells or recA+ cell-free systems. Since the host recA+ allele is required for most phi chi174 recombinant formation, we conclude that the observed figure 8 molecules are intermediates in, or end products of, 1 phi chi174 recombination event. We propose that recombinant figure 8 DNA molecules arise as a result of "single-strand aggression," are stabilized by double-strand "branch migration," and represent a specific example of a common intermediate in genetic recombination.
mesh_terms: D002474:Cell-Free System; D003090:Coliphages / Q000378:metabolism* / Q000648:ultrastructure; D004267:DNA Viruses / Q000378:metabolism / Q000648:ultrastructure; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D008854:Microscopy, Electron; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D011995:Recombination, Genetic
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral