Viroporins are small viral ion channels that play important roles in the viral infection cycle and are proven antiviral drug targets. Matrix protein 2 from influenza A (AM2) is the best characterized viroporin, and the current paradigm is that AM2 forms monodisperse tetramers. Here, we used native mass spectrometry and other techniques to characterize the oligomeric state of both the full-length and transmembrane domain (TM) of AM2 in a variety of different pH and detergent conditions. Unexpectedly, we discovered that AM2 formed a range of different oligomeric complexes that were strongly influenced by the local chemical environment. Native mass spectrometry of AM2 in nanodiscs with different lipids showed that lipids also affected the oligomeric states of AM2. Finally, nanodiscs uniquely enabled measurement of amantadine binding stoichiometries to AM2 in the intact lipid bilayer. These unexpected results reveal that AM2 can form a wider range of oligomeric states than previously thought possible, which may provide new potential mechanisms of influenza pathology and pharmacology.

中文翻译：

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甲型流感 M2 通道寡聚化对其化学环境敏感

病毒孔蛋白是小的病毒离子通道，在病毒感染周期中起着重要作用，并且是被证明的抗病毒药物靶点。来自甲型流感 (AM2) 的基质蛋白 2 是表征最好的病毒孔蛋白，目前的范例是 AM2 形成单分散四聚体。在这里，我们使用原生质谱和其他技术来表征 AM2 的全长和跨膜结构域 (TM) 在各种不同的 pH 值和洗涤剂条件下的寡聚状态。出乎意料的是，我们发现 AM2 形成了一系列受当地化学环境强烈影响的不同寡聚复合物。具有不同脂质的纳米圆盘中 AM2 的天然质谱表明，脂质也影响 AM2 的寡聚状态。最后，nanodiscs 独特地实现了对完整脂质双层中金刚烷胺与 AM2 结合化学计量的测量。这些意想不到的结果表明，AM2 可以形成比以前认为的更广泛的寡聚状态，这可能为流感病理学和药理学提供新的潜在机制。