Ng Kenneth K-S, Pendás-Franco Natalia, Rojo Jorge, Boga José A, Machín Angeles, Alonso José M Martín, Parra Francisco
Division of Biochemistry, Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
J Biol Chem. 2004 Apr 16;279(16):16638-45. doi: 10.1074/jbc.M400584200. Epub 2004 Feb 5.
Norwalk virus is a major cause of acute gastroenteritis for which effective treatments are sorely lacking. To provide a basis for the rational design of novel antiviral agents, the main replication enzyme in Norwalk virus, the virally encoded RNA-dependent RNA polymerase (RdRP), has been expressed in an enzymatically active form, and its structure has been crystallographically determined both in the presence and absence of divalent metal cations. Although the overall fold of the enzyme is similar to that seen previously in the RdRP from rabbit hemorrhagic disease virus, the carboxyl terminus, surprisingly, is located in the active site cleft in five independent copies of the protein in three distinct crystal forms. The location of this carboxyl-terminal segment appears to interfere with the binding of double-stranded RNA in the active site cleft and may play a role in the initiation of RNA synthesis or mediate interactions with accessory replication proteins.
诺如病毒是急性肠胃炎的主要病因，目前严重缺乏有效的治疗方法。为了给新型抗病毒药物的合理设计提供依据，诺如病毒的主要复制酶——病毒编码的RNA依赖性RNA聚合酶（RdRP）已以具有酶活性的形式表达出来，并且其结构已在存在和不存在二价金属阳离子的情况下通过晶体学确定。尽管该酶的整体折叠与先前在兔出血性疾病病毒的RdRP中所见的相似，但令人惊讶的是，在三种不同晶体形式的蛋白质的五个独立拷贝中，羧基末端位于活性位点裂隙中。该羧基末端片段的位置似乎会干扰双链RNA在活性位点裂隙中的结合，并且可能在RNA合成的起始中起作用或介导与辅助复制蛋白的相互作用。
