MOE Joint International Research Laboratory of Animal Health and Food Safety, Engineering Laboratory of Animal Immunity of Jiangsu Province, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
PLoS Pathog. 2022 Sep 9;18(9):e1010835. doi: 10.1371/journal.ppat.1010835. eCollection 2022 Sep.
Influenza A viruses effectively hijack the intracellular "resources" to complete transcription and replication, which involve extensive interactions between the viral and host proteins. Herein, we screened the host factors, which belong to DExD/H-box protein family members, RNA-binding proteins or mitochondrial anchoring proteins, to investigate their effects on polymerase activity. We observed DDX39B and DDX39A, DEAD-box RNA-Helicases, exert a dual effect on regulating polymerase activity and replication of influenza A viruses. We further revealed that DDX39B and DDX39A interact with viral NP and NS1 proteins. Interestingly, the viral NP proteins could reverse the inhibitory effect of excess DDX39B or DDX39A on polymerase activity. Mechanistically, the TREX complex subunits, THOC1, THOC4 and CIP29, were recruited to DDX39B-DDX39A-NP complex in an ATP-dependent manner, via the interaction with DDX39B or DDX39A, followed by excess TREX-NP complexes interfere with the normal oligomerization state of NP depending on the ratio between the viral and host proteins. On the other hand, the TREX complex, an evolutionarily conserved protein complex, is responsible for the integration of several mRNA processing steps to export viral mRNA. Knockdown of TREX complex subunits significantly down-regulated viral titers and protein levels, accompanied by retention of viral mRNA in the nucleus. Taken together, screening the host factors that regulate the replication of influenza virus advances our understanding of viral pathogenesis and our findings point out a previously unclear mechanism of TREX complex function.
甲型流感病毒有效地劫持细胞内的“资源”来完成转录和复制，这涉及到病毒和宿主蛋白之间的广泛相互作用。在此，我们筛选了宿主因子，这些因子属于 DExD/H 盒蛋白家族成员、RNA 结合蛋白或线粒体锚定蛋白，以研究它们对聚合酶活性的影响。我们观察到 DEAD 盒 RNA 解旋酶 DDX39B 和 DDX39A 对调节甲型流感病毒聚合酶活性和复制具有双重作用。我们进一步揭示 DDX39B 和 DDX39A 与病毒 NP 和 NS1 蛋白相互作用。有趣的是，病毒 NP 蛋白可以逆转过多的 DDX39B 或 DDX39A 对聚合酶活性的抑制作用。从机制上讲，TREX 复合物亚基 THOC1、THOC4 和 CIP29 通过与 DDX39B 或 DDX39A 的相互作用，以依赖 ATP 的方式被招募到 DDX39B-DDX39A-NP 复合物中，随后过量的 TREX-NP 复合物会干扰 NP 的正常寡聚状态，这取决于病毒和宿主蛋白之间的比例。另一方面，TREX 复合物是一种进化上保守的蛋白质复合物，负责整合几个 mRNA 加工步骤以输出病毒 mRNA。TREX 复合物亚基的敲低显著下调了病毒滴度和蛋白水平，同时伴随着病毒 mRNA 在核内的滞留。总之，筛选调节流感病毒复制的宿主因子可以增进我们对病毒发病机制的理解，我们的研究结果指出了 TREX 复合物功能的一个以前不明确的机制。
