宿主因子ANP32家族成员调控流感病毒聚合酶活性的分子机制

流感病毒聚合酶介导其基因组的复制和转录，对病毒生命周期至关重要。流感病毒基因组的复制分为两个步骤，首先以病毒RNA（vRNA）为模板合成与之互补的RNA（cRNA），再以cRNA为模板合成vRNA。这两个过程的起始机制完全不同，前者于末端起始合成AG双核苷酸，然后直接延伸合成cRNA；后者则在内部起始合成AG双核苷酸，然后通过重排使AG与模板末端配对，再延伸合成完整的子代vRNA。目前关于聚合酶进行重排的机制还不清楚。我们前期研究发现宿主编码的ANP32A能促进D型流感聚合酶的重排，表明这一过程可能依赖宿主因子的调控。本项目拟通过结构生物学手段解析D型流感聚合酶与RNA和ANP32A的复合物结构，并结合体外酶活、细胞复制子以及反向遗传学等手段，阐明ANP32A调控聚合酶进行重排的分子机制，深化我们对流感基因组复制过程及调控机理的了解，为靶向病毒聚合酶或宿主因子的抗病毒药物研发提供理论基础。

Influenza virus polymerase (FluPol) is responsible for transcription and replication of the viral genome, playing a pivotal role in the life cycle of influenza viruses. The replication of viral genomic RNA (vRNA) involves two steps. Initially, the FluPol synthesizes a complementary RNA (cRNA) using the vRNA as the template. The cRNA then serves as the template to produce progeny vRNA. The two steps of RNA synthesis are initiated via different mechanisms. For the first step, it is initiated by producing an AG di-nucleotide using the terminal residues of 3’-vRNA as the template, which would then be directly elongated to produce the full-length cRNA. In contrast, the second step, from cRNA to vRNA, is initiated internally to produce the AG di-nucleotide that would undergo realignment to pair with the terminal residues of 3’-cRNA before processive elongation of the vRNA product. However, the mechanism of re-alignment in replication by FluPol is yet unknown. In our previous studies, we have found that the host factor ANP32A (Acidic Nuclear Phosphoprotein 32 Family Member A) significantly promoted the re-alignment events during vRNA synthesis by influenza D virus polymers (FluDPol), suggesting the stringent regulation of this process by host factors. In this project, we will determine the complex structure of FluDPol bound to RNA and ANP32A. Combined with in vitro polymerase activity assays, in vivo replicon systems and reverse genetics approaches, we intend to elucidate the mechanism of how ANP32A specifically facilitates the re-alignment process during vRNA synthesis. These findings will improve our understanding in the process of influenza virus replication and its regulation by host factors, and provide an important basis for developing drugs.