The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins.
The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins.
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SARS-CoV-2 辅助蛋白 Orf3a 不是离子通道，但确实与运输蛋白相互作用。
DOI：
10.7554/elife.84477
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发表时间：
2023-01-25
期刊：
影响因子：
7.7
通讯作者：
Clapham DE
中科院分区：
文献类型：
--
作者：
Miller AN;Houlihan PR;Matamala E;Cabezas-Bratesco D;Lee GY;Cristofori-Armstrong B;Dilan TL;Sanchez-Martinez S;Matthies D;Yan R;Yu Z;Ren D;Brauchi SE;Clapham DE
严重急性呼吸综合征相关冠状病毒2（SARS-CoV-2）和SARS-CoV-1辅助蛋白Orf 3a与质膜、内吞途径和高尔基体的标记物共定位。一些报告已经导致将两种Orf 3a蛋白注释为病毒孔蛋白。在这里，我们表明，无论是SARS-CoV-2或SARS-CoV-1 Orf 3a形成功能性离子传导孔和电导测量是常见的污染物在过表达和高水平的蛋白质在重建研究。SARS-CoV-2和SARS-CoV-1 Orf 3a的Cryo-EM结构都显示出狭窄的收缩和带正电荷的水前庭的存在，这不利于阳离子渗透。我们观察到SARS-CoV-2 Orf 3a过表达后晚期内体标记Rab 7的富集，以及与VPS 39的共免疫沉淀。有趣的是，SARS-CoV-1 Orf 3a不会引起与SARS-CoV-2 Orf 3a相同的细胞表型，也不会与VPS 39相互作用。为了解释这种差异，我们发现SARS-CoV-2 Orf 3a的发散的非结构化环促进其与VPS 39的结合，VPS 39是一种HOPS复合物拴系蛋白，参与晚期内体和自噬体与溶酶体的融合。我们认为，增加的环增强了SARS-CoV-2 Orf 3a的能力，以增选宿主细胞运输机制的病毒退出或宿主免疫逃避。
The severe acute respiratory syndrome associated coronavirus 2 (SARS-CoV-2) and SARS-CoV-1 accessory protein Orf3a colocalizes with markers of the plasma membrane, endocytic pathway, and Golgi apparatus. Some reports have led to annotation of both Orf3a proteins as viroporins. Here, we show that neither SARS-CoV-2 nor SARS-CoV-1 Orf3a form functional ion conducting pores and that the conductances measured are common contaminants in overexpression and with high levels of protein in reconstitution studies. Cryo-EM structures of both SARS-CoV-2 and SARS-CoV-1 Orf3a display a narrow constriction and the presence of a positively charged aqueous vestibule, which would not favor cation permeation. We observe enrichment of the late endosomal marker Rab7 upon SARS-CoV-2 Orf3a overexpression, and co-immunoprecipitation with VPS39. Interestingly, SARS-CoV-1 Orf3a does not cause the same cellular phenotype as SARS-CoV-2 Orf3a and does not interact with VPS39. To explain this difference, we find that a divergent, unstructured loop of SARS-CoV-2 Orf3a facilitates its binding with VPS39, a HOPS complex tethering protein involved in late endosome and autophagosome fusion with lysosomes. We suggest that the added loop enhances SARS-CoV-2 Orf3a’s ability to co-opt host cellular trafficking mechanisms for viral exit or host immune evasion.
影响因子：
3.8
作者：
Ackerman, M J;Wickman, K D;Clapham, D E
通讯作者：
Clapham, D E