Sock E, Wegner M, Fortunato E A, Grummt F
Institut für Biochemie, Universität Würzburg, Germany.
Virology. 1993 Dec;197(2):537-48. doi: 10.1006/viro.1993.1627.
The requirements for the DNA replication of the human papovavirus JC were analyzed using JC T-antigen as well as the T-antigens of the related viruses SV40 and BK. With all three T-antigens, the boundary of the core origin mapped on the early side to position 5093 of the viral genome. In conjunction with earlier studies, the core origin of DNA replication was therefore defined as a 68-bp region which, similar to the SV40 core origin, contains three major structural elements, early palindrome, T-antigen binding site II, and A/T-rich tract. Replication was stimulated by sequences flanking the core origin on the early side. Specifically, the stimulating sequences on the early side were identified as T-antigen binding site I. The degree to which flanking sequences were able to stimulate viral DNA replication was dependent on the T-antigen used in the experiment, with JC T-antigen relying most and BK T-antigen relying least on the flanking sequences. SV40 T-antigen showed an intermediate dependence. The same hierarchy was observed when replication activities were compared. BK T-antigen was more active in replicating DNA than SV40 T-antigen, which in turn was more effective than JC T-antigen. Dependence on flanking sequences is, thus, inversely correlated to the replicating activity of the respective T-antigen, showing that, in addition to the origin, the T-antigen contributes to the characteristics of JC virus DNA replication.
利用JC T抗原以及相关病毒SV40和BK的T抗原，分析了人乳头多瘤病毒JC的DNA复制需求。对于所有这三种T抗原，核心起始位点的边界在早期一侧定位于病毒基因组的5093位。结合早期研究，DNA复制的核心起始位点因此被定义为一个68碱基对的区域，该区域与SV40核心起始位点类似，包含三个主要结构元件，即早期回文序列、T抗原结合位点II和富含A/T的区域。核心起始位点早期一侧的侧翼序列可刺激复制。具体而言，早期一侧的刺激序列被确定为T抗原结合位点I。侧翼序列刺激病毒DNA复制的程度取决于实验中使用的T抗原，其中JC T抗原对侧翼序列的依赖最大，BK T抗原对侧翼序列的依赖最小。SV40 T抗原表现出中等程度的依赖性。比较复制活性时也观察到相同的等级关系。BK T抗原在复制DNA方面比SV40 T抗原更活跃，而SV40 T抗原又比JC T抗原更有效。因此，对侧翼序列的依赖与各自T抗原的复制活性呈负相关，这表明除了起始位点外，T抗原也对JC病毒DNA复制的特性有贡献。
