A second nonstructural protein functions in the regulation of alphavirus negative-strand RNA synthesis.
A second nonstructural protein functions in the regulation of alphavirus negative-strand RNA synthesis.
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第二种非结构蛋白在调节甲病毒负链 RNA 合成中发挥作用。
DOI：
10.1128/jvi.67.6.3605-3610.1993
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发表时间：
1993
影响因子：
5.4
通讯作者：
Sawicki,SG
中科院分区：
文献类型：
--
作者：
Sawicki,DL;Sawicki,SG
既往研究（D.L.萨维奇D. B。Barkhimer，S. G.萨维奇角M. Rice和S. Schlesinger，Virology 174：43-52，1990）鉴定了辛德毕斯病毒非结构蛋白4（nsP 4）中的温度敏感性（ts）缺陷，其在复制早期结束时正常停止后重新激活负链合成。我们现在报告两个不同的ts改变nsP 2的Ala-517到Thr在ts 17或Asn-700到Lys在ts 133，也重新激活负链合成。这些相同的突变导致严重减少蛋白酶加工的nsP 2和识别的内部启动子的亚基因组mRNA的合成，并负责这些突变体的条件致死性和RNA阴性。在nsP 2突变的负链合成的重新激活类似于在nsP 4：这是一个稳定的复制复合物的可逆性，并不需要继续病毒蛋白质的合成。表达突变nsP 2和nsP 4的重组病毒比单独的突变蛋白更有效地重新激活负链合成，这与nsP 2和nsP 4参与模板识别的假设一致。我们建议，这些改变导致nsP 2和nsP 4切换从他们的正常偏好，以识别负链作为模板，以识别正链，从而模仿复制复合物的初始形成。
Previous studies (D.L. Sawicki, D. B. Barkhimer, S. G. Sawicki, C. M. Rice, and S. Schlesinger, Virology 174:43-52, 1990) identified a temperature-sensitive (ts) defect in Sindbis virus nonstructural protein 4 (nsP4) that reactivated negative-strand synthesis after its normal cessation at the end of the early phase of replication. We now report identification of two different ts alterations in nsP2 of Ala-517 to Thr in ts17 or Asn-700 to Lys in ts133 that also reactivated negative-strand synthesis. These same mutations caused severely reduced protease processing by nsP2 and recognition of the internal promoter for subgenomic mRNA synthesis and were responsible for the conditional lethality and RNA negativity of these mutants. Reactivation of negative-strand synthesis by mutations in nsP2 resembled that in nsP4: it was a reversible property of stable replication complexes and did not require continuation of viral protein synthesis. Recombinant viruses expressing both mutant nsP2 and nsP4 reactivated negative-strand synthesis more efficiently than did either mutant protein alone, consistent with the hypothesis that both nsP2 and nsP4 participate in template recognition. We propose that these alterations cause nsP2 and nsP4 to switch from their normal preference to recognize negative strands as templates to recognize positive strands and thereby mimic the initial formation of a replication complex.