title: Sequence relations among the IncY plasmid p15B, P1, and P7 prophages.
abstract: Electron microscopic analysis of heteroduplex molecules between the 94-kb plasmid p15B and the 92-kb phage P1 genome revealed nine regions of nonhomology, eight substitutions, and two neighboring insertions. Overall, the homologous segments correspond to 83% of the P1 genome and 81% of p15B. Heteroduplex molecules between p15B and the 99-kb phage P7 genome showed nonhomology in eight of the same nine regions; in addition, two new nonhomologous segments are present and P7 carries a 5-kb insertion representing Tn902. The DNA homology between those two genomes amounts to 79% of P7 DNA and 83% of p15B. Plasmid p15B contains two stem-loop structures. One of them has no equivalent structure on P1 and P7 DNA. The other substitutes the invertible C segments of P1 and P7 and their flanking sequences including cin, the gene for the site-specific recombinase mediating inversion.
mesh_terms: D003090:Coliphages / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D008854:Microscopy, Electron; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral