Institute for Molecular Virology, University of Wisconsin-Madison, R.M. Bock Laboratories, 1525 Linden Dr. Madison, WI 53706, USA.
Virology. 2013 Aug 15;443(1):177-85. doi: 10.1016/j.virol.2013.05.002. Epub 2013 May 25.
Encephalomyocarditis virus (EMCV), a Cardiovirus, initiates its polyprotein with a short 67 amino acid Leader (L) sequence. The protein acts as a unique pathogenicity factor, with anti-host activities which include the triggering of nuclear pore complex hyperphosphorylation and direct binding inhibition of the active cellular transport protein, Ran GTPase. Chemical modifications and protein mutagenesis now map the Ran binding domain to the L hinge-linker region, and in particular, to amino acids 35-40. Large deletions affecting this region were shown previously to diminish Ran binding. New point mutations, especially K35Q, D37A and W40A, preserve the intact L structure, abolish Ran binding and are deficient for nucleoporin (Nup) hyperphosphorylation. Ran itself morphs through multiple configurations, but reacts most effectively with L when in the GDP format, preferably with an empty nucleotide binding pocket. Therefore, L:Ran binding, mediated by the linker-hinge, is a required step in L-induced nuclear transport inhibition.
脑炎心肌炎病毒（EMCV）是一种心血管病毒，其多蛋白以一个短的 67 个氨基酸的 Leader（L）序列起始。该蛋白作为一种独特的致病性因子，具有抗宿主活性，包括触发核孔复合体过度磷酸化和直接结合抑制活性细胞转运蛋白 Ran GTPase。化学修饰和蛋白质诱变现在将 Ran 结合域映射到 L 铰链连接区，特别是到氨基酸 35-40。先前的研究表明，影响该区域的大片段缺失会降低 Ran 结合。新的点突变，特别是 K35Q、D37A 和 W40A，保留了完整的 L 结构，取消了 Ran 结合，并且对核孔蛋白（Nup）过度磷酸化缺陷。Ran 本身通过多种构象变化，但在 GDP 形式下与 L 反应最有效，最好是与空核苷酸结合口袋。因此，由连接铰链介导的 L:Ran 结合是 L 诱导的核转运抑制的必需步骤。
