Mol Plant Microbe Interact. 2014 Oct;27(10):1107-18. doi: 10.1094/MPMI-02-14-0035-R.
Alfalfa mosaic virus (AMV) coat protein (CP) is essential for many steps in virus replication from early infection to encapsidation. However, the identity and functional relevance of cellular factors that interact with CP remain unknown. In an unbiased yeast two-hybrid screen for CP-interacting Arabidopsis proteins, we identified several novel protein interactions that could potentially modulate AMV replication. In this report, we focus on one of the novel CP-binding partners, the Arabidopsis PsbP protein, which is a nuclear-encoded component of the oxygen-evolving complex of photosystem II. We validated the protein interaction in vitro with pull-down assays, in planta with bimolecular fluorescence complementation assays, and during virus infection by co-immunoprecipitations. CP interacted with the chloroplast-targeted PsbP in the cytosol and mutations that prevented the dimerization of CP abolished this interaction. Importantly, PsbP overexpression markedly reduced virus accumulation in infected leaves. Taken together, our findings demonstrate that AMV CP dimers interact with the chloroplast protein PsbP, suggesting a potential sequestration strategy that may preempt the generation of any PsbP-mediated antiviral state.
紫花苜蓿花叶病毒（AMV）外壳蛋白（CP）对于病毒从早期感染到包装的复制过程中的许多步骤都是必不可少的。然而，与 CP 相互作用的细胞因子的身份和功能相关性仍然未知。在针对 CP 相互作用的拟南芥蛋白的无偏酵母双杂交筛选中，我们鉴定了几种可能潜在调节 AMV 复制的新的蛋白相互作用。在本报告中，我们重点介绍了一种新的 CP 结合伴侣，即拟南芥 PsbP 蛋白，它是光系统 II 放氧复合物的核编码组成部分。我们通过下拉测定、双分子荧光互补测定和共免疫沉淀在体外、体内和病毒感染期间验证了蛋白相互作用。CP 在细胞质中与定位于叶绿体的 PsbP 相互作用，并且阻止 CP 二聚化的突变会破坏这种相互作用。重要的是，PsbP 的过表达显著降低了感染叶片中的病毒积累。总之，我们的发现表明，AMV CP 二聚体与叶绿体蛋白 PsbP 相互作用，表明可能存在一种隔离策略，可以防止任何由 PsbP 介导的抗病毒状态的产生。
