A Glycoprotein Mutation That Emerged during the 2013-2016 Ebola Virus Epidemic Alters Proteolysis and Accelerates Membrane Fusion.
A Glycoprotein Mutation That Emerged during the 2013-2016 Ebola Virus Epidemic Alters Proteolysis and Accelerates Membrane Fusion.
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DOI：
10.1128/mbio.03616-20
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发表时间：
2021-02-16
期刊：
影响因子：
6.4
通讯作者：
Chandran K
中科院分区：
文献类型：
--
作者：
Fels JM;Bortz RH 3rd;Alkutkar T;Mittler E;Jangra RK;Spence JS;Chandran K
2013-2016年西非埃博拉病毒疫情期间病毒分离株的基因组监测，这是有记录以来最大和最具破坏性的丝状病毒爆发，揭示了几种新的突变。负责的菌株名为Makona，在糖蛋白（GP）的第82位（A82 V）处携带A至V的取代，这与体外感染性增强有关。在这里，我们研究了这种增强的机制基础以及A82 V和GP残基544处的T至I取代之间的相互作用，这也调节了细胞培养物的感染性。我们发现82 V和544 I都使GP不稳定，544位的残基影响整体稳定性，而82 V特异性地使蛋白水解切割的GP不稳定。这两个残基还促进活细胞中病毒和宿主膜的脂质混合的更快动力学，单独和串联，这与与病毒受体尼曼-匹克C1（NPC 1）共定位后融合的更快时间相关。此外，携带82 V的GP对组织蛋白酶L（CatL）的蛋白水解更敏感，组织蛋白酶L是病毒进入的关键宿主因子。有趣的是，CatL将82 V变体GP加工成分子量约为12，000（12 K）的新产物，我们假设其对应于预先触发融合的GP形式。因此，我们提出了一个模型，其中82 V促进更有效的GP处理的CatL，导致更快的病毒融合动力学和更高水平的感染性。
Genomic surveillance of viral isolates during the 2013–2016 Ebola virus epidemic in Western Africa, the largest and most devastating filovirus outbreak on record, revealed several novel mutations. The responsible strain, named Makona, carries an A-to-V substitution at position 82 (A82V) in the glycoprotein (GP), which is associated with enhanced infectivity in vitro. Here, we investigated the mechanistic basis for this enhancement as well as the interplay between A82V and a T-to-I substitution at residue 544 of GP, which also modulates infectivity in cell culture. We found that both 82V and 544I destabilize GP, with the residue at position 544 impacting overall stability, while 82V specifically destabilizes proteolytically cleaved GP. Both residues also promote faster kinetics of lipid mixing of the viral and host membranes in live cells, individually and in tandem, which correlates with faster times to fusion following colocalization with the viral receptor Niemann-Pick C1 (NPC1). Furthermore, GPs bearing 82V are more sensitive to proteolysis by cathepsin L (CatL), a key host factor for viral entry. Intriguingly, CatL processed 82V variant GPs to a novel product with a molecular weight of approximately 12,000 (12K), which we hypothesize corresponds to a form of GP that is pre-triggered for fusion. We thus propose a model in which 82V promotes more efficient GP processing by CatL, leading to faster viral fusion kinetics and higher levels of infectivity.