Non-structural proteins 2 and 3 interact to modify host cell membranes during the formation of the arterivirus replication complex
Non-structural proteins 2 and 3 interact to modify host cell membranes during the formation of the arterivirus replication complex
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DOI：
10.1099/0022-1317-82-5-985
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发表时间：
2001-05-01
影响因子：
3.8
通讯作者：
Pedersen, KW
中科院分区：
文献类型：
--
作者：
Snijder, EJ;van Tol, H;Pedersen, KW
马动脉炎病毒复制酶多蛋白的研究nsp2和nsp3的切割产物之前被发现是相互作用的，这一特性使得nsp2在nsp4蛋白酶加工多蛋白的下游部分时充当辅助因子。值得注意的是，在感染Vero细胞，而不是感染BHK-21或RK-13细胞时，EAV nsp2现在被证明是额外的，内部的切割。在Vero细胞中，大约50%的nsp2 （61 kDa）被切割成18 kDa的n端部分和44 kDa的c端部分，这很可能是由宿主细胞蛋白酶引起的，而BHK-21和RK-13细胞中不存在这种蛋白酶。虽然这一额外处理步骤的功能后果尚不清楚，但在Vero细胞中的实验显示，nsp2的c端部分与nsp3相互作用，大多数EAV nsps定位于病毒诱导的感染细胞核周区域的双膜结构，在那里病毒RNA合成发生。现在的研究表明，在一个表达系统中，nsp2和nsp3的共同表达是诱导形成双膜结构的必要和充分条件，这种结构与感染细胞中发现的结构非常相似。因此，nsp2和nsp3切割产物在哺乳动物细胞中复制的正链RNA病毒常见的两个过程中起着至关重要的作用：复制酶前体的受控蛋白水解和病毒复制复合体的膜结合。
The replicase polyproteins of equine arteritis virus (EAV; family Arteriviridae, order Nidovirales) are processed by three viral proteases to yield 12 non-structural proteins (nsps), The nsp2 and nsp3 cleavage products have previously been found to interact, a property that allows nsp2 to act as a co-factor in the processing of the downstream part of the polyprotein by the nsp4 protease, Remarkably, upon infection of Vero cells, but not of BHK-21 or RK-13 cells, EAV nsp2 is now shown to be subject to an additional, internal, cleavage. In Vero cells, approximately 50% of nsp2 (61 kDa) was cleaved into an 18 kDa N-terminal part and a 44 kDa C-terminal part, most likely by a host cell protease that is absent in BHK-21 and RK-13 cells. Although the functional consequences of this additional processing step are unknown, the experiments in Vero cells revealed that the C-terminal part of nsp2 interacts with nsp3, Most EAV nsps localize to virus-induced double-membrane structures in the perinuclear region of the infected cell, where virus RNA synthesis takes place. It is now shown that, in an expression system, the co-expression of nsp2 and nsp3 is both necessary and sufficient to induce the formation of double-membrane structures that strikingly resemble those found in infected cells. Thus, the nsp2 and nsp3 cleavage products play a crucial role in two processes that are common to positive-strand RNA viruses that replicate in mammalian cells: controlled proteolysis of replicase precursors and membrane association of the virus replication complex.