Viral replication and movement are intimately linked; however, the molecular mechanisms regulating the transition between replication and subsequent movement remain largely unknown. We previously demonstrated that the Barley stripe mosaic virus (BSMV) γb protein promotes viral replication and movement by interacting with the αa replicase and TGB1 movement proteins. Here, we found that γb is palmitoylated at Cys-10, Cys-19, and Cys-60 in Nicotiana benthamiana, which supports BSMV infection. Intriguingly, non-palmitoylated γb is anchored to chloroplast replication sites and enhances BSMV replication, whereas palmitoylated γb protein recruits TGB1 to the chloroplasts and forms viral replication-movement intermediate complexes. At the late stages of replication, γb interacts with NbPAT15 and NbPAT21 and is palmitoylated at the chloroplast periphery, thereby shifting viral replication to intracellular and intercellular movement. We also show that palmitoylated γb promotes virus cell-to-cell movement by interacting with NbREM1 to inhibit callose deposition at the plasmodesmata. Altogether, our experiments reveal a model whereby palmitoylation of γb directs a dynamic switch between BSMV replication and movement events during infection.

中文翻译：

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γb 蛋白的棕榈酰化指导大麦条纹花叶病毒复制和运动之间的动态转换

病毒复制和运动密切相关；然而，调节复制和后续运动之间转变的分子机制在很大程度上仍然未知。我们之前证明，大麦条纹花叶病毒(BSMV) γb 蛋白通过与 αa 复制酶和 TGB1 运动蛋白相互作用来促进病毒复制和运动。在这里，我们发现 γb 在本塞姆氏烟草中的 Cys-10、Cys-19 和 Cys-60 处被棕榈酰化，它支持 BSMV 感染。有趣的是，非棕榈酰化 γb 锚定到叶绿体复制位点并增强 BSMV 复制，而棕榈酰化 γb 蛋白将 TGB1 募集到叶绿体并形成病毒复制运动中间复合物。在复制后期，γb 与 NbPAT15 和 NbPAT21 相互作用，并在叶绿体外围被棕榈酰化，从而将病毒复制转移到细胞内和细胞间运动。我们还表明，棕榈酰化 γb 通过与 NbREM1 相互作用来抑制胞间连丝处的胼胝质沉积，从而促进病毒细胞间运动。总而言之，我们的实验揭示了一个模型，其中 γb 的棕榈酰化指导感染期间 BSMV 复制和运动事件之间的动态切换。