Reed K E, Gorbalenya A E, Rice C M
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
J Virol. 1998 Jul;72(7):6199-206. doi: 10.1128/JVI.72.7.6199-6206.1998.
Phosphorylation of the expressed NS5A protein of hepatitis C virus (HCV), a member of the Hepacivirus genus of the family Flaviviridae, has been demonstrated in mammalian cells and in a cell-free assay by an associated kinase activity. In this report, phosphorylation is also shown for the NS5A and NS5 proteins, respectively, of bovine viral diarrhea virus (BVDV) and yellow fever virus (YF), members of the other two established genera in this family. Phosphorylation of BVDV NS5A and YF NS5 was observed in infected cells, transient expression experiments, and a cell-free assay similar to the one developed for HCV NS5A. Phosphoamino acid analyses indicated that all three proteins were phosphorylated by serine/threonine kinases. Similarities in the properties of BVDV NS5A, YF NS5, and HCV NS5A phosphorylation in vitro further suggested that closely related kinases or the same kinase may phosphorylate these viral proteins. Conservation of this trait among three quite distantly related viruses representing three separate genera suggests that phosphorylation of the NS5A/NS5 proteins or their association with cellular kinases may play an important role in the flavivirus life cycle.
丙型肝炎病毒（HCV）是黄病毒科肝炎病毒属的成员，其表达的NS5A蛋白的磷酸化已在哺乳动物细胞中以及通过相关激酶活性在无细胞试验中得到证实。在本报告中，牛病毒性腹泻病毒（BVDV）和黄热病病毒（YF）（该科另外两个已确定属的成员）的NS5A和NS5蛋白也分别显示出磷酸化。在感染细胞、瞬时表达实验以及与为HCV NS5A开发的类似的无细胞试验中观察到了BVDV NS5A和YF NS5的磷酸化。磷酸氨基酸分析表明，所有这三种蛋白均被丝氨酸/苏氨酸激酶磷酸化。BVDV NS5A、YF NS5和HCV NS5A体外磷酸化特性的相似性进一步表明，密切相关的激酶或同一种激酶可能使这些病毒蛋白磷酸化。在代表三个不同属的三种亲缘关系较远的病毒中这种特性的保守性表明，NS5A/NS5蛋白的磷酸化或它们与细胞激酶的关联可能在黄病毒生命周期中起重要作用。
