Identification of H209 essential for pH 8-triggered receptor-independent syncytium formation by S protein of MHV-A59
Identification of H209 essential for pH 8-triggered receptor-independent syncytium formation by S protein of MHV-A59
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通过 MHV-A59 的 S 蛋白鉴定对 pH 8 触发的受体独立合胞体形成必需的 H209
作者：
Li Pei;Shan Yiwei;Zheng Wangliang;Ou Xiuyuan;Mi Dan;Mu Zhixia;Holmes Kathryn V.;Qian Zhaohui
小鼠冠状病毒小鼠肝炎病毒A59株的刺突糖蛋白(S)以小鼠癌胚抗原相关细胞黏附分子1a为细胞进入受体，但在37℃时，单用pH 8.0也可在没有受体的情况下触发S蛋白的形成。但这种S糖蛋白的构象变化机制尚未确定。我们在37℃时，通过pH 8.0触发MHV-A59 S蛋白的构象变化。PH 8.0引起的S蛋白的构象变化与受体结合引起的构象变化非常相似。我们系统地突变了S蛋白中的15个组氨酸残基，发现H209是pH 8.0触发的RIS形成所必需的，而H179、H441、H643和H759也在这一过程中发挥着重要作用。用丙氨酸取代H209对受体结合没有影响，但在小鼠17Cl.1细胞中。突变体H209A MHV-A59表现出延迟的生长动力学，当与野生型病毒混合时，很容易被野生型病毒击败，这表明H209A突变导致了病毒适应性的缺陷。最后，H209A突变显著增加。S蛋白在预融合构象中的热稳定性可能提高了膜融合所需的S蛋白构象变化的能垒，从而降低了细胞培养中病毒的适合性。因此，MHV-A59可能进化为降低其S蛋白的稳定性，以增加病毒适合性。
The spike glycoprotein (S) of murine coronavirus mouse hepatitis virus.(MHV) strain A59 uses murine carcinoembryonic antigen-related cell adhesion molecule.1a as its receptor for cell entry, but S protein can also be triggered in the absence.of receptor by pH 8.0 alone at 37°C. The mechanism by which conformational.changes of this S glycoprotein can be triggered by pH 8.0 has not yet been determined..Here, we show that MHV-A59 S protein is triggered by pH 8.0 at 37°C to induce.receptor-independent syncytium (RIS) formation on 293T cells, and that the.conformational changes in S proteins triggered by pH 8.0 are very similar to those.triggered by receptor binding. We systemically mutated each of 15 histidine residues.in S protein and found that H209 is essential for pH 8.0-triggered RIS formation,.while H179, H441, H643, and H759 also play important roles in this process. Replacement.of H209 with Ala had no effect on receptor binding, but in murine 17Cl.1 cells.mutant H209A MHV-A59 showed delayed growth kinetics and was readily outcompeted.by wild-type virus when mixed together, indicating that the H209A mutation.caused a defect in virus fitness. Finally, the H209A mutation significantly increased.the thermostability of S protein in its prefusion conformation, which may raise the.energy barrier for conformational change of S protein required for membrane fusion.and lead to a decrease in virus fitness in cell culture. Thus, MHV-A59 may have.evolved to lower the stability of its S protein in order to increase virus fitness.
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影响因子：
3.7
作者：
Matsuyama S;Taguchi F
通讯作者：
Taguchi F
影响因子：
4.5
作者：
Dessau M;Goldhill D;McBride R;Turner PE;Modis Y
通讯作者：
Modis Y
影响因子：
3.7
作者：
Presloid, John B.;Mohammad, Tasneem F.;Lauring, Adam S.;Novella, Isabel S.
通讯作者：
Novella, Isabel S.
DOI：
10.1016/b978-0-444-87312-5.50041-2
发表时间：
1990
期刊：
Virus Infections of Ruminants
影响因子：
--
作者：
通讯作者：
--
影响因子：
4.8
作者：
Carneiro, FA;Stauffer, F;Da Poian, AT
通讯作者：
Da Poian, AT