Department of Biochemistry, Institute for Molecular Virology, University of Wisconsin, Madison, Wisconsin, USA.
J Virol. 2013 Jun;87(11):6517-20. doi: 10.1128/JVI.02493-12. Epub 2013 Mar 27.
The leader (L) protein of encephalomyocarditis virus (EMCV) shuts off host cell nucleocytoplasmic trafficking (NCT) by inducing hyperphosphorylation of nuclear pore proteins. This dramatic effect by a nonenzymatic protein of 6 kDa is not well understood but clearly involves L binding to cellular Ran GTPase, a critical factor of active NCT. Exogenous GDP and GTP are inhibitory to L-Ran binding, but the guanine-nucleotide exchange factor RCC1 can relieve this inhibition. In the presence of RCC1, L binds Ran with a KD (equilibrium dissociation constant) of ≈ 3 nM and reaches saturation within 20 min. The results of fluorescently tagged nucleotide experiments suggest that L-Ran interactions affect the nucleotide-binding pocket of Ran.
脑心肌炎病毒（EMCV）的 L 蛋白通过诱导核孔蛋白的过度磷酸化来阻断宿主细胞的核质转运（NCT）。这种由 6 kDa 的非酶蛋白引起的显著效应尚不清楚，但显然涉及 L 与细胞 Ran GTPase 的结合，Ran GTPase 是活跃的 NCT 的关键因素。外源 GDP 和 GTP 对 L-Ran 结合有抑制作用，但 G 核苷酸交换因子 RCC1 可以解除这种抑制。在 RCC1 存在的情况下，L 与 Ran 的结合 KD（平衡解离常数）约为 3 nM，并且在 20 分钟内达到饱和。荧光标记核苷酸实验的结果表明，L-Ran 相互作用影响 Ran 的核苷酸结合口袋。
