Nipah Virus V Protein Binding Alters MDA5 Helicase Folding Dynamics.

Nipah virus (NiV) is an emerging and deadly zoonotic paramyxovirus that is responsible for periodic epidemics of acute respiratory illness and encephalitis in humans. Previous studies have shown that the NiV V protein antagonizes host antiviral immunity, but the molecular mechanism is incompletely understood. To address this gap, we biochemically characterized NiV V binding to the host pattern recognition receptor MDA5. We find that the C-terminal domain of NiV V (VCTD) is sufficient to bind the MDA5SF2 domain when recombinantly co-expressed in bacteria. Analysis by hydrogen–deuterium exchange mass spectrometry (HDX-MS) studies revealed that NiV VCTD is conformationally dynamic, and binding to MDA5 reduces the dynamics of VCTD. Our results also suggest that the β-sheet region in between the MDA5 Hel1, Hel2, and Hel2i domains exhibits rapid HDX. Upon VCTD binding, these β-sheet and adjacent residues show significant protection. Collectively, our findings suggest that NiV V binding disrupts the helicase fold and dynamics of MDA5 to antagonize host antiviral immunity.

尼帕病毒（NiV）是一种新出现的致命人畜共患副粘病毒，它导致人类周期性爆发急性呼吸道疾病和脑炎。先前的研究表明，尼帕病毒的V蛋白拮抗宿主抗病毒免疫，但分子机制尚未完全了解。为了填补这一空白，我们对尼帕病毒V蛋白与宿主模式识别受体MDA5的结合进行了生化特性研究。我们发现，当在细菌中重组共表达时，尼帕病毒V蛋白的C末端结构域（VCTD）足以与MDA5的SF2结构域结合。氢 - 氘交换质谱（HDX - MS）分析研究表明，尼帕病毒VCTD具有构象动态性，与MDA5结合会降低VCTD的动态性。我们的研究结果还表明，MDA5的Hel1、Hel2和Hel2i结构域之间的β - 折叠区域呈现快速的氢 - 氘交换。在VCTD结合后，这些β - 折叠及相邻残基显示出显著的保护作用。总体而言，我们的研究结果表明，尼帕病毒V蛋白的结合破坏了MDA5的解旋酶折叠和动态性，从而拮抗宿主抗病毒免疫。