Host ANP32A mediates the assembly of the influenza virus replicase
Host ANP32A mediates the assembly of the influenza virus replicase
复制标题
DOI：
10.1038/s41586-020-2927-z
复制
发表时间：
2020-11-18
期刊：
影响因子：
64.8
通讯作者：
Grimes, Jonathan M.
中科院分区：
文献类型：
--
作者：
Carrique, Loic;Fan, Haitian;Grimes, Jonathan M.
水生鸟类是一个巨大的宿主，新的大流行性甲型流感病毒可以从中出现（1）。流感病毒含有负义节段RNA基因组，其在病毒核糖核蛋白复合物的背景下由病毒异源三聚体RNA聚合酶（FluPol）转录和复制（2，3）。由于酸性核磷蛋白32（ANP 32）的物种特异性差异，A型禽流感病毒（FluPolA）的RNA聚合酶在人类细胞中无法有效复制病毒RNA，ANP 32是FluPol活性的必需宿主蛋白家族（4）。宿主适应性突变，特别是PB 2亚基627结构域中氨基酸残基627（E627 K）处的谷氨酸至赖氨酸突变，使禽流感病毒能够克服这种限制，并在人ANP 32蛋白存在下有效复制病毒RNA。然而，基因组复制的分子机制以及与ANP 32蛋白的相互作用在很大程度上仍然未知。在这里，我们报告的冷冻电镜结构的流感病毒C聚合酶（FluPolC）在复杂的人和鸡ANP 32A。在这两种结构中，两个FluPolC分子形成由ANP 32A的N-末端富含亮氨酸的重复结构域桥接的不对称二聚体。ANP 32A的C-末端低复杂性酸性区域插入不对称FluPolA二聚体的两个并置的PB 2 627结构域之间，表明适应性PB 2（E627 K）突变如何使病毒RNA在哺乳动物宿主中复制的机制。我们提出，这种复合物代表了病毒RNA基因组的复制平台，其中一个FluPol分子充当复制酶，而另一个则启动新生复制产物组装成病毒核糖核蛋白复合物。
Aquatic birds represent a vast reservoir from which new pandemic influenza A viruses can emerge(1). Influenza viruses contain a negative-sense segmented RNA genome that is transcribed and replicated by the viral heterotrimeric RNA polymerase (FluPol) in the context of viral ribonucleoprotein complexes(2,3). RNA polymerases of avian influenza A viruses (FluPolA) replicate viral RNA inefficiently in human cells because of species-specific differences in acidic nuclear phosphoprotein 32 (ANP32), a family of essential host proteins for FluPol activity(4). Host-adaptive mutations, particularly a glutamic-acid-to-lysine mutation at amino acid residue 627 (E627K) in the 627 domain of the PB2 subunit, enable avian FluPolA to overcome this restriction and efficiently replicate viral RNA in the presence of human ANP32 proteins. However, the molecular mechanisms of genome replication and the interplay with ANP32 proteins remain largely unknown. Here we report cryo-electron microscopy structures of influenza C virus polymerase (FluPolC) in complex with human and chicken ANP32A. In both structures, two FluPolC molecules form an asymmetric dimer bridged by the N-terminal leucine-rich repeat domain of ANP32A. The C-terminal low-complexity acidic region of ANP32A inserts between the two juxtaposed PB2 627 domains of the asymmetric FluPolA dimer, suggesting a mechanism for how the adaptive PB2(E627K) mutation enables the replication of viral RNA in mammalian hosts. We propose that this complex represents a replication platform for the viral RNA genome, in which one of the FluPol molecules acts as a replicase while the other initiates the assembly of the nascent replication product into a viral ribonucleoprotein complex.