Hamelin C, D'Amours B, Pagé C, Chung Y S
Centre de recherche en virologie, Institut Armand-Frappier, Laval-des-Rapides, QC, Canada.
Biochem Cell Biol. 1994 May-Jun;72(5-6):195-201. doi: 10.1139/o94-029.
Simian virus 40 (SV40) chromatin extracted from nuclei of infected monkey cells (CV1) was sedimented in neutral sucrose gradients, before and after digestion with bovine pancreatic RNase I-A or DNase I. DNA topoisomerase (TI) activity was found associated with RNase-resistant, DNase-sensitive SV40 nucleoprotein complexes. After polyacrylamide gel electrophoresis, a number of proteins with a molecular mass between 40 and 70 kDa were seen at the level of viral DNA peaks, some of which may represent catalytically active breakdown products of the TI enzyme. Large protein complexes were observed under the electron microscope in association with the viral chromosomes and appear to correspond to the SV40 DNA replication complex, including TI. Our results suggest that TI activity is indeed associated with the viral minichromosomes undergoing replication in vivo.
从感染猴细胞（CV1）的细胞核中提取的猿猴病毒40（SV40）染色质，在用牛胰核糖核酸酶I-A或脱氧核糖核酸酶I消化之前和之后，在中性蔗糖梯度中进行沉降。发现DNA拓扑异构酶（TI）活性与核糖核酸酶抗性、脱氧核糖核酸酶敏感性的SV40核蛋白复合物相关。聚丙烯酰胺凝胶电泳后，在病毒DNA峰水平可见一些分子量在40至70 kDa之间的蛋白质，其中一些可能代表TI酶的具有催化活性的降解产物。在电子显微镜下观察到与病毒染色体相关的大蛋白质复合物，似乎对应于包括TI在内的SV40 DNA复制复合物。我们的结果表明，TI活性确实与体内正在进行复制的病毒微型染色体相关。
