Utama A, Shimizu H, Morikawa S, Hasebe F, Morita K, Igarashi A, Hatsu M, Takamizawa K, Miyamura T
Department of Bioprocessing, Faculty of Agriculture, Gifu University, 1-1 Yanagido, Gifu, Japan.
FEBS Lett. 2000 Jan 7;465(1):74-8. doi: 10.1016/s0014-5793(99)01705-6.
The NS3 protein of Japanese encephalitis virus (JEV) contains motifs typical of RNA helicase/NTPase but no RNA helicase activity has been reported for this protein. To identify and characterize the RNA helicase activity of JEV NS3, a truncated form of the protein with a His-tag was expressed in Escherichia coli and purified. The purified JEV NS3 protein showed an RNA helicase activity, which was dependent on divalent cations and ATP. An Asp-285-to-Ala substitution in motif II of the JEV NS3 protein abolished the ATPase and RNA helicase activities. These results indicate that the C-terminal 457 residues are sufficient to exhibit the RNA helicase activity of JEV NS3.
日本脑炎病毒（JEV）的NS3蛋白含有RNA解旋酶/NTPase的典型基序，但尚未报道该蛋白具有RNA解旋酶活性。为了鉴定和表征JEV NS3的RNA解旋酶活性，在大肠杆菌中表达并纯化了带有His标签的该蛋白截短形式。纯化后的JEV NS3蛋白表现出RNA解旋酶活性，该活性依赖于二价阳离子和ATP。JEV NS3蛋白基序II中的天冬氨酸285突变为丙氨酸消除了ATP酶和RNA解旋酶活性。这些结果表明，C末端的457个残基足以展现JEV NS3的RNA解旋酶活性。
