State Key Laboratory of Agro-Biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China.
College of Plant Protection, China Agricultural University, Beijing, China.
Elife. 2022 Feb 22;11:e74884. doi: 10.7554/eLife.74884.
Liquid-liquid phase separation (LLPS) plays important roles in forming cellular membraneless organelles. However, how host factors regulate LLPS of viral proteins during negative-sense RNA (NSR) virus infection is largely unknown. Here, we used (BYSMV) as a model to demonstrate regulation of host casein kinase 1 (CK1) in phase separation and infection of NSR viruses. We first found that the BYSMV phosphoprotein (P) formed spherical granules with liquid properties and recruited viral nucleotide (N) and polymerase (L) proteins in vivo. Moreover, the P-formed granules were tethered to the ER/actin network for trafficking and fusion. BYSMV P alone formed droplets and incorporated the N protein and the 5' trailer of genomic RNA in vitro. Interestingly, phase separation of BYSMV P was inhibited by host CK1-dependent phosphorylation of an intrinsically disordered P protein region. Genetic assays demonstrated that the unphosphorylated mutant of BYSMV P exhibited condensed phase, which promoted viroplasm formation and virus replication. Whereas, the phosphorylation-mimic mutant existed in diffuse phase state for virus transcription. Collectively, our results demonstrate that host CK1 modulates phase separation of the viral P protein and virus infection.
液-液相分离 (LLPS) 在形成细胞无膜细胞器方面发挥着重要作用。然而，宿主因子如何调节负义 RNA (NSR) 病毒感染期间病毒蛋白的 LLPS 在很大程度上是未知的。在这里，我们使用 (BYSMV) 作为模型来证明宿主酪蛋白激酶 1 (CK1) 在 NSR 病毒的相分离和感染中的调节作用。我们首先发现，BYSMV 磷蛋白 (P) 形成具有液体特性的球形颗粒，并在体内募集病毒核苷酸 (N) 和聚合酶 (L) 蛋白。此外，P 形成的颗粒与 ER/肌动蛋白网络连接，用于运输和融合。单独的 BYSMV P 形成液滴，并在体外掺入 N 蛋白和基因组 RNA 的 5' 尾。有趣的是，BYSMV P 的相分离被宿主 CK1 依赖性磷酸化内在无序 P 蛋白区域所抑制。遗传分析表明，BYSMV P 的未磷酸化突变体表现出凝聚相，促进病毒质形成和病毒复制。然而，磷酸化模拟突变体存在于病毒转录的弥散相状态。总之，我们的结果表明，宿主 CK1 调节病毒 P 蛋白的相分离和病毒感染。
