Shandong Provincial Key Laboratory of Agricultural Microbiology, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, P. R. China.
Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland.
Mol Plant Microbe Interact. 2021 Jun;34(6):658-668. doi: 10.1094/MPMI-09-20-0265-R. Epub 2021 Jul 21.
Potyviruses move to neighboring cells in the form of virus particles or a coat protein (CP)-containing ribonucleoprotein complex. However, the precise roles of RNA-binding residues in potyviral CP in viral cell-to-cell movement remain to be elucidated. In this study, we predicted the three-dimensional model of tobacco vein banding mosaic virus (TVBMV)-encoded CP and found nine residues presumably located in the CP RNA-binding pocket. Substitutions of the two basic residues at positions 192 and 225 (R and K) with either alanine, cysteine, or glutamic acid abolished TVBMV cell-to-cell and systemic movement in plants. These substitutions also reduced the replication of the mutant viruses. Results from the electrophoretic mobility shift assay showed that the RNA-binding activity of mutant CPs derived from R or K substitutions was significantly lower than that of wild-type CP. Analysis of purified virus particles showed that mutant viruses with R or K substitutions formed RNA-free virus-like particles. Mutations of R and K did not change the CP plasmodesmata localization. The wild-type TVBMV CP could rescue the deficient cell-to-cell movement of mutant viruses. Moreover, deletion of any of the other seven residues also abolished TVBMV cell-to-cell movement and reduced the CP RNA-binding activity. The corresponding nine residues in watermelon mosaic virus CP were also found to play essential roles in virus cell-to-cell movement. In conclusion, residues R and K in the CP RNA-binding pocket are critical for viral RNA binding and affect both virus replication and cell-to-cell movement.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
马铃薯 Y 病毒移动到邻近的细胞中是以病毒粒子或包含外壳蛋白 (CP) 的核糖核蛋白复合物的形式。然而，马铃薯 Y 病毒 CP 中的 RNA 结合残基在病毒细胞间运动中的精确作用仍有待阐明。在这项研究中，我们预测了烟草叶脉镶嵌病毒 (TVBMV)-编码 CP 的三维模型，并发现了九个假定位于 CP RNA 结合口袋中的残基。用丙氨酸、半胱氨酸或谷氨酸替换位置 192 和 225 的两个碱性残基 (R 和 K)，会使 TVBMV 在植物体内的细胞间和系统运动能力丧失。这些取代也降低了突变病毒的复制。电泳迁移率变动分析的结果表明，来自 R 或 K 取代的突变 CP 的 RNA 结合活性明显低于野生型 CP。对纯化病毒粒子的分析表明，带有 R 或 K 取代的突变病毒形成了无 RNA 的病毒样颗粒。R 和 K 的突变并没有改变 CP 通过胞间连丝的定位。野生型 TVBMV CP 可以拯救突变病毒的细胞间运动缺陷。此外，缺失其他七个残基中的任何一个也会使 TVBMV 的细胞间运动能力丧失，并降低 CP 的 RNA 结合活性。西瓜花叶病毒 CP 中的相应九个残基也被发现对病毒的细胞间运动至关重要。总之，CP RNA 结合口袋中的 R 和 K 残基对于病毒 RNA 结合至关重要，影响病毒的复制和细胞间运动。[公式：见文本]版权所有 2021 作者。这是一个开放获取的文章，根据 CC BY-NC-ND 4.0 国际许可分发。
