An Ping, Brodsky Jeffrey L, Pipas James M
Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
Arch Biochem Biophys. 2015 May 1;573:23-31. doi: 10.1016/j.abb.2015.02.033. Epub 2015 Mar 6.
Several human polyomaviruses including JCV, BKV and TSV are associated with diseases, particularly in immunosuppressed patients. While the large T antigen (LT) encoded by the monkey polyomavirus SV40 is well studied, and possesses intrinsic ATPase and DNA helicase activities, the LTs of the human polyomaviruses are relatively uncharacterized. In order to evaluate whether these enzymatic activities, which are required for viral DNA replication, are conserved between polyomaviruses, we performed a comparative study using the LTs from JCV, TSV and SV40. The ATPase and DNA helicase activities and the interaction with the cellular tumor suppressor p53 were assayed for the purified Zn-ATPase domains of the three LTs. We found that all Zn-ATPases were active ATPases. The Zn-ATPase domains also functioned as DNA helicases, although the measured kinetic constants differed among the three proteins. In addition, when tested against four small molecule ATPase inhibitors, the Zn-ATPase domains of TSV was more resistant than that of SV40 and JCV. Our results show that, while LTs from JCV and TSV share the core ATPase and DNA helicase activities, they possess important functional differences that might translate into their respective abilities to infect and replicate in hosts.
包括JCV、BKV和TSV在内的几种人类多瘤病毒与疾病相关，尤其是在免疫抑制患者中。虽然猴多瘤病毒SV40编码的大T抗原（LT）已得到充分研究，且具有内在的ATP酶和DNA解旋酶活性，但人类多瘤病毒的LTs相对未被充分表征。为了评估病毒DNA复制所需的这些酶活性在多瘤病毒之间是否保守，我们使用JCV、TSV和SV40的LTs进行了一项比较研究。对三种LTs的纯化锌ATP酶结构域的ATP酶和DNA解旋酶活性以及与细胞肿瘤抑制因子p53的相互作用进行了测定。我们发现所有锌ATP酶都是活性ATP酶。锌ATP酶结构域也起到DNA解旋酶的作用，尽管三种蛋白质的测量动力学常数有所不同。此外，在针对四种小分子ATP酶抑制剂进行测试时，TSV的锌ATP酶结构域比SV40和JCV的更具抗性。我们的结果表明，虽然JCV和TSV的LTs具有核心ATP酶和DNA解旋酶活性，但它们具有重要的功能差异，这可能转化为它们各自在宿主中感染和复制的能力。
