Nightingale K P, Fox K R
Department of Physiology and Pharmacology, University of Southampton, U.K.
Biochem J. 1992 Jun 15;284 ( Pt 3)(Pt 3):929-34. doi: 10.1042/bj2840929.
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.
已使用各种足迹技术研究了博来霉素与动质体DNA片段的相互作用。该DNA呈现弯曲结构，由于其腺嘌呤的相位排列，在凝胶上的迁移率异常低。与其他显示凝胶迁移速率降低的DNA相反，博来霉素-钴复合物增加了该DNA片段的迁移率，这表明抗生素可能通过解旋机制消除了DNA弯曲。通过羟基自由基足迹法证实了弯曲的消除，在配体存在的情况下，该方法产生了更均匀的条带梯。博来霉素的切割位点是G-嘧啶序列，尽管并非所有此类位点都受到相同程度的影响，并且在GA和GG处也发现了一些切割。DNase I足迹法证实了抗生素结合位点，但显示一些强切割位点并未产生足迹。博来霉素使其切割位点（GT、GC和GA）3'侧的腺嘌呤对焦碳酸二乙酯高度敏感。
