title: DNA unwinding ability of Xenopus transcription factor A.
abstract: The duplex DNA unwinding ability of Xenopus transcription factor A was examined by treatment of plasmid-protein complexes with calf thymus topoisomerase I and resolution of the topoisomer distributions by agarose gel electrophoresis. Factor A binding to plasmids does result in a small degree of unwinding as evidenced by a shift in topoisomer distributions upon relaxation. Slightly more unwinding by factor A was observed on a specific plasmid, containing four tandemly repeated 5S RNA genes, when compared to a non-specific plasmid of nearly identical size containing no 5S specific sequences. The amount of unwinding observed on the specific plasmid, about one base-pair per gene, suggests that unwinding of the DNA duplex is not an important aspect of binding of factor A to the 5S RNA gene.
mesh_terms: D000818:Animals; D004265:DNA Helicases / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D010957:Plasmids; D013950:Thymus Gland / Q000201:enzymology; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014981:Xenopus
chemical_list: D014157:Transcription Factors; D004265:DNA Helicases; D004264:DNA Topoisomerases, Type I