Shin C G, Snapka R M
Department of Radiology, Ohio State University, Columbus 43210-1214.
Biochemistry. 1990 Dec 11;29(49):10934-9. doi: 10.1021/bi00501a011.
Exposure of infected CV-1 cells to specific type I and type II topoisomerase poisons caused strong protein association with distinct subsets of simian virus 40 (SV40) DNA replication intermediates. On the basis of the known specificity and mechanisms of action of these drugs, the proteins involved are assumed to be the respective topoisomerases. Camptothecin, a topoisomerase I poison, caused strong protein association with form II (relaxed circular) and form III (linear) viral genomes and replication intermediates having broken DNA replication forks but not with form I (superhelical) viral DNA or normal late replication intermediates which were present. In contrast, type II topoisomerase poisons caused completely replicated forms and late viral replication forms to be tightly bound to protein--some to a greater extent than others. Different type II topoisomerase inhibitors caused distinctive patterns of protein association with the replication intermediates present. Both intercalating and nonintercalating type II topoisomerase poisons caused a small amount of form I (superhelical) SV40 DNA to be protein-associated in vivo. The protein complex with form I viral DNA was entirely drug-dependent and strong, but apparently noncovalent. The protein associated with form I DNA may represent a drug-stabilized "topological complex" between type II topoisomerase and SV40 DNA.
将受感染的CV-1细胞暴露于特定的I型和II型拓扑异构酶毒物中，会导致蛋白质与猿猴病毒40（SV40）DNA复制中间体的不同亚组强烈结合。基于这些药物已知的特异性和作用机制，推测所涉及的蛋白质分别为各自的拓扑异构酶。喜树碱是一种拓扑异构酶I毒物，它会导致蛋白质与II型（松弛环状）和III型（线性）病毒基因组以及具有断裂DNA复制叉的复制中间体强烈结合，但不会与I型（超螺旋）病毒DNA或存在的正常晚期复制中间体结合。相反，II型拓扑异构酶毒物会使完全复制的形式和晚期病毒复制形式与蛋白质紧密结合——有些结合程度比其他的更高。不同的II型拓扑异构酶抑制剂会导致与存在的复制中间体的蛋白质结合呈现出不同的模式。嵌入型和非嵌入型II型拓扑异构酶毒物都会在体内使少量I型（超螺旋）SV40 DNA与蛋白质结合。与I型病毒DNA形成的蛋白质复合物完全依赖于药物且结合牢固，但显然是非共价的。与I型DNA结合的蛋白质可能代表II型拓扑异构酶与SV40 DNA之间的药物稳定化“拓扑复合物”。
