Zhang Shijian, Wang Qiang, Wang Jinlan, Mizumoto Kiyohisa, Toyoda Tetsuya
Unit of Viral Genome Regulation, Institut Pasteur of Shanghai, Chinese Academy of Sciences, 411 Hefei Road, 200025 Shanghai, PR China.
Biochim Biophys Acta. 2012 Jan;1819(1):78-83. doi: 10.1016/j.bbagrm.2011.11.006. Epub 2011 Nov 30.
Influenza virus RNA polymerase (RdRp) PB2 is the cap-1 binding subunit and determines host range and pathogenicity. The mutant human influenza virus RdRp containing PB2 D701N and D701N/S714R demonstrated enhanced replicon activity in mammalian cells. We investigated the influence of these mutations on RdRp activity. Cap-1-dependent transcription activities of D701N/S714R, D701N, and S714R were 348.1±6.2%, 146.4±11%, and 250.1±0.8% of that of the wild type (wt), respectively. Replication activity of these mutants for complimentary RNA to viral RNA ranged from 44% to 53% of that of the wt. Cap-1 RNA-binding activities of D701N/S714R, D701N, and S714R were 262±25%, 257±34%, and 315±9.6% of that of the wt, respectively, and their cap-dependent endonuclease activities were similar to that of the wt. These mutations did not affect template RNA-binding activities. D701N and S714R mutations enhanced transcription by enhancing cap-1 RNA-binding activity, but they may exhibit decreased efficiency of priming by the cap-1 primer. These mutations at the C-terminal domain of PB2 may affect its cap-binding domain.
流感病毒RNA聚合酶（RdRp）PB2是帽-1结合亚基，决定宿主范围和致病性。含有PB2 D701N和D701N/S714R的突变型人类流感病毒RdRp在哺乳动物细胞中表现出增强的复制子活性。我们研究了这些突变对RdRp活性的影响。D701N/S714R、D701N和S714R的帽-1依赖性转录活性分别为野生型（wt）的348.1±6.2%、146.4±11%和250.1±0.8%。这些突变体对病毒RNA互补RNA的复制活性为野生型的44%至53%。D701N/S714R、D701N和S714R的帽-1 RNA结合活性分别为野生型的262±25%、257±34%和315±9.6%，它们的帽依赖性内切核酸酶活性与野生型相似。这些突变不影响模板RNA结合活性。D701N和S714R突变通过增强帽-1 RNA结合活性来增强转录，但它们可能表现出帽-1引物引发效率降低。PB2 C末端结构域的这些突变可能会影响其帽结合结构域。
