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一株H5N1NS1蛋白第101位点的甲硫氨酸决定该蛋白抗干扰素能力及亚细胞定位

, PP. 787-794

Keywords: A型流感病毒,H5N1,NS1,干扰素&beta,CPSF30,核输出信号

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Abstract:

A型流感病毒NS1蛋白有两种抗干扰素(IFN)机制,一种通过抑制RIG-Ⅰ信号转导完成,另一种通过与CPSF30结合,阻断细胞前体mRNA剪切和加工.目前,NS1拮抗Ⅰ型IFN生成的具体机制还不是十分清楚.本文结果显示,PR/8/34NS1蛋白部分定位于细胞质,并且表现出很强的、特异性抑制IFN-β启动子活性的能力,而H5N1NS1则明显不同.H5N1NS1主要定位细胞核,它抑制IFN的能力相对较弱,是通过抑制细胞基因整体表达水平实现的.本研究通过构建H5N1NS1的一系列突变后发现,仅将H5N1NS1的101位点的甲硫氨酸突变为PR/8/34NS1相应位点的异亮氨酸(命名为H5-M101I)即可获得了特异性抑制IFN-β启动子活性的能力,并且使该蛋白向细胞质定位,同时失去与CPSF30结合的能力.本研究还发现,之前报道的定位于138~147氨基酸位点的核输出信号(NES)并没有发挥功能.这表明,很可能存在尚未发现的其他氨基酸具有NES功能.结果表明,101位点的甲硫氨酸(Met-101)可能与其临近的第100位亮氨酸(Leu-100)共同增强了此区域的NES;除此之外,Met-101也是NS1与CPSF30结合的关键氨基酸.综上所述,本文揭示了Met-101在H5N1流感病毒生活周期中的重要性,同时为抗病毒工作提供了有价值的信息.

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