Unité de Virologie et Immunologie Moléculaires (UR892), INRA, Université Paris-Saclay, Jouy-en-Josas, France.
UMR1173, INSERM, Université de Versailles St. Quentin, Montigny le Bretonneux, France.
PLoS Pathog. 2018 Feb 28;14(3):e1006920. doi: 10.1371/journal.ppat.1006920. eCollection 2018 Mar.
Respiratory syncytial virus (RSV) RNA synthesis occurs in cytoplasmic inclusion bodies (IBs) in which all the components of the viral RNA polymerase are concentrated. In this work, we show that RSV P protein recruits the essential RSV transcription factor M2-1 to IBs independently of the phosphorylation state of M2-1. We also show that M2-1 dephosphorylation is achieved by a complex formed between P and the cellular phosphatase PP1. We identified the PP1 binding site of P, which is an RVxF-like motif located nearby and upstream of the M2-1 binding region. NMR confirmed both P-M2-1 and P-PP1 interaction regions in P. When the P-PP1 interaction was disrupted, M2-1 remained phosphorylated and viral transcription was impaired, showing that M2-1 dephosphorylation is required, in a cyclic manner, for efficient viral transcription. IBs contain substructures called inclusion bodies associated granules (IBAGs), where M2-1 and neo-synthesized viral mRNAs concentrate. Disruption of the P-PP1 interaction was correlated with M2-1 exclusion from IBAGs, indicating that only dephosphorylated M2-1 is competent for viral mRNA binding and hence for a previously proposed post-transcriptional function.
呼吸道合胞病毒（RSV）的 RNA 合成发生在细胞质包含体（IBs）中，病毒 RNA 聚合酶的所有成分都集中在其中。在这项工作中，我们表明 RSV P 蛋白独立于 M2-1 的磷酸化状态将必需的 RSV 转录因子 M2-1 募集到 IBs 中。我们还表明，M2-1 的去磷酸化是由 P 与细胞磷酸酶 PP1 形成的复合物实现的。我们确定了 P 与 PP1 的结合位点，该位点位于 M2-1 结合区域的附近和上游，是一个 RVxF 样基序。NMR 确认了 P 中 P-M2-1 和 P-PP1 相互作用区域。当 P-PP1 相互作用被破坏时，M2-1 仍然保持磷酸化，病毒转录受到损害，表明 M2-1 的去磷酸化是必需的，以循环方式促进有效的病毒转录。IBs 包含称为包含体相关颗粒（IBAGs）的亚结构，其中 M2-1 和新合成的病毒 mRNA 集中。P-PP1 相互作用的破坏与 M2-1 从 IBAGs 中的排除相关，表明只有去磷酸化的 M2-1 才有能力结合病毒 mRNA，从而发挥先前提出的转录后功能。
