Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
Virology. 2011 Jul 20;416(1-2):16-25. doi: 10.1016/j.virol.2011.04.013. Epub 2011 May 18.
To study the contribution of the protease-sensitive loop of the VSV M protein in virus assembly we recovered recombinant VSV (rVSV) with mutations in this region and examined virus replication. Mutations in the highly conserved LXD motif (aa 123-125) resulted in reduced virion budding, reduced virus titers and enhanced M protein exchange with M-ribonucleocapsid complexes (M-RNPs), suggesting that the mutant M proteins were less tightly associated with RNP skeletons. In addition, viral protein synthesis began to decrease at 4h post-infection (hpi) and was reduced by ~80% at 8 hpi for the mutant rVSV-D125A. The reduced protein synthesis was not due to decreased VSV replication or transcription; however, translation of a reporter gene with an EMCV IRES was not reduced, suggesting that cap-dependent, but not cap-independent translation initiation was affected in rVSV-D125A infected cells. These results indicate that the LXD motif is involved in both virus assembly and VSV protein translation.
为了研究 VSV M 蛋白蛋白酶敏感环在病毒组装中的作用，我们恢复了该区域发生突变的重组 VSV(rVSV)，并检测了病毒复制情况。在高度保守的 LXD 基序（aa123-125）中发生突变会导致病毒出芽减少、病毒滴度降低，以及 M 蛋白与 M-核糖核蛋白复合物（M-RNP）的交换增强，这表明突变的 M 蛋白与 RNP 骨架的结合不那么紧密。此外，病毒蛋白合成在感染后 4 小时（hpi）开始下降，突变的 rVSV-D125A 在 8 hpi 时减少了约 80%。这种蛋白合成的减少不是由于 VSV 复制或转录减少引起的；然而，带有 EMCV IRES 的报告基因的翻译并没有减少，这表明在 rVSV-D125A 感染的细胞中，帽依赖性翻译起始而不是帽非依赖性翻译起始受到了影响。这些结果表明，LXD 基序参与了病毒组装和 VSV 蛋白翻译。
