title: Interaction of bleomycin with a bent DNA fragment.
abstract: The interaction of bleomycin with a kinetoplast DNA fragment has been examined using various footprinting techniques. This DNA adopts a bent structure and displays an unusually low gel mobility on account of its phased runs of adenines. The bleomycin-cobalt complex increases the mobility of this DNA fragment, in contrast with other DNAs which show a decreased rate of gel migration, suggesting that the antibiotic removes DNA bending, possibly via an unwinding mechanism. Removal of the bending is confirmed by hydroxy-radical footprinting which produces a more even ladder of bands in the presence of the ligand. Cleavage by bleomycin is at the sequence G-pyrimidine, though not all such sites are affected to the same extent and some cutting is found at GA and GG. DNase I footprinting confirms the antibiotic-binding sites but reveals that some strong cleavage sites do not yield footprints. Bleomycin renders adenines on the 3' side of its cleavage sites (GT, GC and GA) hyper-reactive to diethyl pyrocarbonate.
authors.affiliation: Department of Physiology and Pharmacology, University of Southampton, U.K.
authors.forename: K P
authors.initials: KP
authors.lastname: Nightingale
authors.forename: K R
authors.initials: KR
authors.lastname: Fox
mesh_terms: D001483:Base Sequence; D001761:Bleomycin / Q000737:chemistry*; D004270:DNA, Circular / Q000737:chemistry* / Q000235:genetics; D018105:DNA, Kinetoplast; D003850:Deoxyribonuclease I; D005609:Free Radicals; D006878:Hydroxides; D017665:Hydroxyl Radical; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids; D015183:Restriction Mapping
chemical_list: D004270:DNA, Circular; D018105:DNA, Kinetoplast; D005609:Free Radicals; D006878:Hydroxides; D001761:Bleomycin; D017665:Hydroxyl Radical; D003850:Deoxyribonuclease I