title: Topological linkage of circular DNA molecules promoted by Ustilago rec 1 protein and topoisomerase.
abstract: We studied the formation of linked circular DNA molecules promoted by the combined action of rec 1 protein and type I topoisomerase of Ustilago maydis. When ATP was added as cofactor to reactions containing rec 1 protein, pairs of homologous circular DNA molecules became linked after addition of topoisomerase. Closed circular duplex molecules could be joined at homologous sites with circular single-stranded molecules or with other circular duplex molecules, provided that homologous single-stranded DNA fragments or RNA polymerase and nucleoside triphosphates were also added. Complexes formed were topologically linked through regions of heteroduplex DNA. When the analog adenylyl-imidodiphosphate was substituted for ATP, nonhomologous pairs of circular DNA molecules became linked.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D001487:Basidiomycota / Q000235:genetics*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004270:DNA, Circular / Q000378:metabolism*; D043211:Exodeoxyribonuclease V; D005656:Fungal Proteins / Q000494:pharmacology*; D008040:Genetic Linkage; D009690:Nucleic Acid Conformation / Q000187:drug effects; D014588:Ustilago / Q000235:genetics*
chemical_list: D004270:DNA, Circular; D005656:Fungal Proteins; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D043211:Exodeoxyribonuclease V; D004264:DNA Topoisomerases, Type I