与多瘤病毒大肿瘤抗原相关的拓扑异构酶活性

Topoisomerase activity associated with polyoma virus large tumor antigen.

作者信息

Marton A, Marko B, Delbecchi L, Bourgaux P

机构信息

Department of Microbiology, Faculty of Medicine, Université de Sherbrooke, Québec, Canada.

出版信息

Biochim Biophys Acta. 1995 May 17;1262(1):59-63. doi: 10.1016/0167-4781(95)00050-q.

DOI:10.1016/0167-4781(95)00050-q

PMID:7772600

Abstract

Polyomavirus (Py) large tumor antigen (LT) was produced in mammalian or insect cells infected with a suitable viral expression vector, and purified by a procedure combining immunoprecipitation with ion-exchange chromatography. Fractions containing the bulk of LT displayed a DNA-relaxing activity (LT-topo) which could be attributed neither to topoisomerase II (topo II) nor to topoisomerase I (topo I) encoded by the cell or the viral vector. On the one hand, LT-topo relaxed pBR322 DNA in a reaction which, unlike that characteristic of topo II, was ATP-independent and inhibited by camptothecin. On the other hand, serum from scleroderma patients which strongly inhibited calf thymus topo I had no effect on LT-topo, which absolutely required Mg2+ ions to relax DNA. Thus, LT-topo is either inherent to LT or belongs to a LT-bound enzyme similar to, but distinct from, topo I.

摘要

多瘤病毒（Py）大T抗原（LT）在感染了合适病毒表达载体的哺乳动物或昆虫细胞中产生，并通过免疫沉淀与离子交换色谱相结合的方法进行纯化。含有大部分LT的组分表现出一种DNA松弛活性（LT-topo），这种活性既不能归因于细胞或病毒载体编码的拓扑异构酶II（topo II），也不能归因于拓扑异构酶I（topo I）。一方面，LT-topo在一个反应中使pBR322 DNA松弛，该反应与topo II的特征不同，不依赖ATP且受喜树碱抑制。另一方面，硬皮病患者血清强烈抑制小牛胸腺topo I，但对LT-topo没有影响，LT-topo绝对需要Mg2+离子来松弛DNA。因此，LT-topo要么是LT固有的，要么属于一种与topo I相似但不同的与LT结合的酶。