PhD Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung 40227, Taiwan.
Graduate Institute of Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan.
Plant Physiol. 2022 Feb 4;188(2):1061-1080. doi: 10.1093/plphys/kiab519.
Infection cycles of viruses are highly dependent on membrane-associated host factors. To uncover the infection cycle of Bamboo mosaic virus (BaMV) in detail, we purified the membrane-associated viral complexes from infected Nicotiana benthamiana plants and analyzed the involved host factors. Four isoforms of voltage-dependent anion channel (VDAC) proteins on the outer membrane of mitochondria were identified due to their upregulated expression in the BaMV complex-enriched membranous fraction. Results from loss- and gain-of-function experiments indicated that NbVDAC2, -3, and -4 are essential for efficient BaMV accumulation. During BaMV infection, all NbVDACs concentrated into larger aggregates, which overlapped and trafficked with BaMV virions to the structure designated as the "dynamic BaMV-induced complex." Besides the endoplasmic reticulum and mitochondria, BaMV replicase and double-stranded RNAs were also found in this complex, suggesting the dynamic BaMV-induced complex is a replication complex. Yeast two-hybrid and pull-down assays confirmed that BaMV triple gene block protein 1 (TGBp1) could interact with NbVDACs. Confocal microscopy revealed that TGBp1 is sufficient to induce NbVDAC aggregates, which suggests that TGBp1 may play a pivotal role in the NbVDAC-virion complex. Collectively, these findings indicate that NbVDACs may associate with the dynamic BaMV-induced complex via TGBp1 and NbVDAC2, -3, or -4 and can promote BaMV accumulation. This study reveals the involvement of mitochondrial proteins in a viral complex and virus infection.
病毒的感染循环高度依赖于膜相关的宿主因子。为了详细揭示竹嵌纹病毒（BaMV）的感染循环，我们从感染的 Nicotiana benthamiana 植物中纯化了膜相关的病毒复合物，并分析了涉及的宿主因子。由于在富含 BaMV 复合物的膜部分中表达上调，鉴定出了线粒体的外膜上的四个电压依赖性阴离子通道（VDAC）蛋白同工型。功能丧失和获得实验的结果表明，NbVDAC2、-3 和 -4 对于高效 BaMV 积累是必需的。在 BaMV 感染期间，所有 NbVDAC 都集中到更大的聚集体中，这些聚集体与 BaMV 病毒粒子重叠并运输到被称为“动态 BaMV 诱导复合物”的结构中。除了内质网和线粒体，BaMV 复制酶和双链 RNA 也在这个复合物中被发现，这表明动态 BaMV 诱导复合物是一个复制复合物。酵母双杂交和下拉实验证实了 BaMV 三基因结合蛋白 1（TGBp1）可以与 NbVDACs 相互作用。共聚焦显微镜显示 TGBp1 足以诱导 NbVDAC 聚集体，这表明 TGBp1 可能在 NbVDAC-病毒粒子复合物中发挥关键作用。总的来说，这些发现表明，NbVDACs 可能通过 TGBp1 和 NbVDAC2、-3 或 -4 与动态 BaMV 诱导复合物相关，并能促进 BaMV 积累。本研究揭示了线粒体蛋白在病毒复合物和病毒感染中的参与。
