Nuclear MxA proteins form a complex with influenza virus NP and inhibit the transcription of the engineered influenza virus genome.
Nuclear MxA proteins form a complex with influenza virus NP and inhibit the transcription of the engineered influenza virus genome.
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DOI：
10.1093/nar/gkh192
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发表时间：
2004-01
影响因子：
14.9
通讯作者：
K. Turan;M. Mibayashi;K. Sugiyama;Shoko Saito;Akiko Numajiri;K. Nagata
中科院分区：
文献类型：
--
作者：
K. Turan;M. Mibayashi;K. Sugiyama;Shoko Saito;Akiko Numajiri;K. Nagata
MX蛋白属于高相对分子质量GTP酶的动力蛋白超家族，可干扰多种病毒的增殖。早期的研究表明，核小鼠Mx1和人类MxA被设计为定位在细胞核中，抑制流感病毒基因组的转录步骤。在这里，我们建立了一个以荧光素酶为报告基因的瞬时流感病毒转录系统，并在细胞中表达了三个RNA聚合酶亚基PB1、PB2和PA以及NP。我们利用这个报告实验系统和核定位的MXA蛋白来为阐明MXA的抗流感病毒活性提供线索。核定位的VP16-mxa和mxa-tag NLS强烈干扰流感病毒的转录。PB2的过表达使核MxA的转录抑制略有恢复，而PB1和PA的过表达不影响MxA的活性。有趣的是，核MXA的抑制活性明显被NP的过度表达所中和。不含C-末端但含有N-末端RNA结合区的NP也以剂量依赖的方式中和VP16-Mxa的活性，而缺乏N-末端的NP不影响VP16-Mxa的活性。此外，不仅VP16-MxA，而且野生型MXA在流感病毒感染细胞中也与NP相互作用。这表明，核MXA不仅与PB2相互作用，而且与NP相互作用，从而抑制流感病毒的转录。
Mx proteins belong to the dynamin superfamily of high molecular weight GTPases and interfere with multiplication of a wide variety of viruses. Earlier studies show that nuclear mouse Mx1 and human MxA designed to be localized in the nucleus inhibit the transcription step of the influenza virus genome. Here we set a transient influenza virus transcription system using luciferase as a reporter gene and cells expressing the three RNA polymerase subunits, PB1, PB2 and PA, and NP. We used this reporter assay system and nuclear-localized MxA proteins to get clues for elucidating the anti-influenza virus activity of MxA. Nuclear-localized VP16-MxA and MxA-TAg NLS strongly interfered with the influenza virus transcription. Over-expression of PB2 led to a slight resumption of the transcription inhibition by nuclear MxA, whereas over-expression of PB1 and PA did not affect the MxA activity. Of interest is that the inhibitory activity of the nuclear MxA was markedly neutralized by over-expression of NP. An NP devoid of its C-terminal region, but containing the N-terminal RNA binding domain, also neutralized the VP16-MxA activity in a dose-dependent manner, whereas an NP lacking the N-terminal region did not affect the VP16-MxA activity. Further, not only VP16-MxA but also the wild-type MxA was found to interact with NP in influenza virus-infected cells. This indicates that the nuclear MxA suppresses the influenza virus transcription by interacting with not only PB2 but also NP.