Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Plant Physiol. 2024 Nov 4;196(3):1826-1839. doi: 10.1093/plphys/kiae436.
Geminiviruses infect numerous crops and cause extensive agricultural losses worldwide. During viral infection, geminiviral C4/AC4 proteins relocate from the plasma membrane to chloroplasts, where they inhibit the production of host defense signaling molecules. However, mechanisms whereby C4/AC4 proteins are transported to chloroplasts are unknown. We report here that tomato (Solanum lycopersicum) COAT PROTEIN COMPLEX I (COPI) components play a critical role in redistributing Tomato yellow leaf curl virus C4 protein to chloroplasts via an interaction between the C4 and β subunit of COPI. Coexpression of both proteins promotes the enrichment of C4 in chloroplasts that is blocked by a COPI inhibitor. Overexpressing or downregulating gene expression of COPI components promotes or inhibits the viral infection, respectively, suggesting a proviral role of COPI components. COPI components play similar roles in C4/AC4 transport and infections of two other geminiviruses: Beet curly top virus and East African cassava mosaic virus. Our results reveal an unconventional role of COPI components in protein trafficking to chloroplasts during geminivirus infection and suggest a broad-spectrum antiviral strategy in controlling geminivirus infections in plants.
双生病毒感染众多作物，在全球范围内造成广泛的农业损失。在病毒感染过程中，双生病毒的 C4/AC4 蛋白从质膜转移到叶绿体，在那里它们抑制宿主防御信号分子的产生。然而，C4/AC4 蛋白被转运到叶绿体的机制尚不清楚。我们在这里报告，番茄（Solanum lycopersicum）COAT PROTEIN COMPLEX I（COP I）成分通过 C4 和 COPIβ亚基之间的相互作用，在将番茄黄曲叶病毒 C4 蛋白重新分配到叶绿体中发挥关键作用。两种蛋白的共表达促进了 C4 在叶绿体中的富集，而 COPI 抑制剂则阻断了这一过程。过表达或下调 COPI 成分的基因表达分别促进或抑制病毒感染，这表明 COPI 成分具有助病毒作用。COPI 成分在两种其他双生病毒（甜菜曲顶病毒和东非木薯花叶病毒）的 C4/AC4 转运和感染中发挥类似作用。我们的结果揭示了 COPI 成分在双生病毒感染期间参与叶绿体蛋白运输的非常规作用，并提出了一种控制植物双生病毒感染的广谱抗病毒策略。
