Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
Nat Commun. 2022 Jan 11;13(1):251. doi: 10.1038/s41467-021-27950-w.
Influenza A viruses cause seasonal epidemics and global pandemics, representing a considerable burden to healthcare systems. Central to the replication cycle of influenza viruses is the viral RNA-dependent RNA polymerase which transcribes and replicates the viral RNA genome. The polymerase undergoes conformational rearrangements and interacts with viral and host proteins to perform these functions. Here we determine the structure of the 1918 influenza virus polymerase in transcriptase and replicase conformations using cryo-electron microscopy (cryo-EM). We then structurally and functionally characterise the binding of single-domain nanobodies to the polymerase of the 1918 pandemic influenza virus. Combining these functional and structural data we identify five sites on the polymerase which are sensitive to inhibition by nanobodies. We propose that the binding of nanobodies at these sites either prevents the polymerase from assuming particular functional conformations or interactions with viral or host factors. The polymerase is highly conserved across the influenza A subtypes, suggesting these sites as effective targets for potential influenza antiviral development.
甲型流感病毒会引发季节性流行和全球大流行，对医疗体系造成了相当大的负担。流感病毒复制周期的核心是依赖 RNA 的 RNA 聚合酶，该酶转录和复制病毒 RNA 基因组。聚合酶会发生构象重排，并与病毒和宿主蛋白相互作用以执行这些功能。在这里，我们使用冷冻电镜（cryo-EM）确定了 1918 年流感病毒聚合酶在转录酶和复制酶构象下的结构。然后，我们对单域纳米抗体与 1918 年大流行流感病毒聚合酶的结合进行了结构和功能表征。结合这些功能和结构数据，我们确定了聚合酶上的五个位点对纳米抗体的抑制敏感。我们提出，纳米抗体在这些位点的结合要么阻止聚合酶采用特定的功能构象，要么阻止其与病毒或宿主因子相互作用。聚合酶在甲型流感病毒各亚型中高度保守，这表明这些位点是有希望用于开发抗流感病毒药物的有效靶标。
