State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China; Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100005, China.
Virus Res. 2020 Jan 2;275:197793. doi: 10.1016/j.virusres.2019.197793. Epub 2019 Oct 29.
Zika virus (ZIKV) is an emergent flavivirus associated with severe neurological disorders. ZIKV NS3 protein is a viral protease that cleaves the ZIKV polyprotein precursor into individual viral proteins. In this study, we found that ZIKV NS3 by itself exhibited mitochondrial localization, which was quite different from its endoplasmic reticulum (ER) localization in ZIKV-infected cells. We screened viral proteins and identified NS2B as the bona fide recruiter of NS3 to the ER. The NS2B C-terminal tail interacted with NS3 protease domain to retain NS3 on the ER. β-Sheet motifs that formed between NS2B and the NS3 protease domain played important roles in their interaction, while mutation in the β-strand of NS2B attenuated NS2B-NS3 interaction and impaired the ability of NS3 protease to cleave the polyprotein precursor into multiple viral proteins. Consequently, NS2B mutations led to severe inhibition of ZIKV replication and production due to insufficient NS3 protease activity. In summary, our study reveals the critical role of NS2B in NS3 recruitment and protease function and provides mechanistic insight into ZIKV replication.
Zika 病毒（ZIKV）是一种新兴的黄病毒，与严重的神经紊乱有关。ZIKV NS3 蛋白是一种病毒蛋白酶，可将 ZIKV 多蛋白前体切割成单个病毒蛋白。在这项研究中，我们发现 ZIKV NS3 本身具有线粒体定位，这与 ZIKV 感染细胞中内质网（ER）定位有很大不同。我们筛选了病毒蛋白，并鉴定出 NS2B 是 NS3 向 ER 募集的真正衔接蛋白。NS2B C 末端尾巴与 NS3 蛋白酶结构域相互作用，将 NS3 保留在 ER 上。NS2B 和 NS3 蛋白酶结构域之间形成的β-折叠基序在它们的相互作用中发挥重要作用，而 NS2B 的β-链突变则削弱了 NS2B-NS3 相互作用，并损害了 NS3 蛋白酶将多蛋白前体切割成多个病毒蛋白的能力。因此，由于 NS3 蛋白酶活性不足，NS2B 突变导致 ZIKV 复制和产生受到严重抑制。总之，我们的研究揭示了 NS2B 在 NS3 募集和蛋白酶功能中的关键作用，并为 ZIKV 复制提供了机制见解。
