title: Transcription-dependent recombination induced by triple-helix formation.
abstract: The homologous recombination between direct repeat sequences separated by either 200 or 1000 bp was induced by active transcription of the downstream gene when poly(dG)-poly(dC) sequences exist between the two direct repeats. This dG tract-mediated and transcription-induced recombination was RecA independent, and the frequency of recombination was dependent on both the length and the orientation of the poly(dG)-poly(dC) sequences relative to the gene. An intramolecular dG.dG.dC triplex formation was detected in Escherichia coli cells in a length-dependent manner when the transcription of the downstream gene was activated. We suggest that the negative superhelical strain generated by active transcription of the downstream gene induces poly(dG)-poly(dC) sequences to adopt a triple-helix structure in vivo and that this structure brings two remote sequences together to stimulate homologous recombination.
authors.affiliation: La Jolla Cancer Research Foundation, California 92037.
authors.forename: Y
authors.initials: Y
authors.lastname: Kohwi
authors.forename: Y
authors.initials: Y
authors.lastname: Panchenko
mesh_terms: D001483:Base Sequence; D004274:DNA, Recombinant / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids; D011089:Polydeoxyribonucleotides / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics; D011995:Recombination, Genetic; D014158:Transcription, Genetic
chemical_list: D004274:DNA, Recombinant; D011089:Polydeoxyribonucleotides; C016681:poly(dG).poly(dC); D011938:Rec A Recombinases