Host cell entry of Middle East respiratory syndrome coronavirus after two-step, furin-mediated activation of the spike protein
Host cell entry of Middle East respiratory syndrome coronavirus after two-step, furin-mediated activation of the spike protein
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DOI：
10.1073/pnas.1407087111
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发表时间：
2014-10-21
影响因子：
11.1
通讯作者：
Whittaker, Gary R.
中科院分区：
文献类型：
--
作者：
Millet, Jean Kaoru;Whittaker, Gary R.
中东呼吸综合征冠状病毒（MERS-CoV）是一种新发现的β冠状病毒，在人类中引起高发病率和死亡率。冠状病毒刺突（S）蛋白是病毒进入的主要决定因素，尽管先前显示MERS-CoV S可以被各种蛋白酶激活，但融合的蛋白水解激活机制的细节仍不完全表征。在这里，我们发现了MERS-CoV S的独特特征。我们确定，通过生物信息学和肽切割试验，两个切割位点弗林蛋白酶，一种普遍表达的蛋白酶，这是位于S1/S2接口和在S2'的位置的S蛋白。我们表明，虽然S1/S2位点是蛋白水解加工弗林蛋白酶在蛋白质的生物合成过程中，S2'网站被切割后，病毒进入。MERS-CoV假病毒体感染显示通过升高的弗林蛋白酶表达水平而增强，并且可以通过弗林蛋白酶siRNA沉默而减少进入。增强的弗林蛋白酶活性似乎部分覆盖了MERS-CoV进入的低pH依赖性。弗林蛋白酶活性的抑制显示出减少MERS-CoV S介导的进入以及病毒的感染。总的来说，我们发现MERS冠状病毒已经进化出一种不寻常的两步弗林蛋白酶激活融合，暗示了在出现到人类群体的过程中的作用。MERS-CoV以这种方式使用弗林蛋白酶的能力，沿着其他蛋白酶，可以解释病毒的多变性。
Middle East respiratory syndrome coronavirus (MERS-CoV) is a newly identified betacoronavirus causing high morbidity and mortality in humans. The coronavirus spike (S) protein is the main determinant of viral entry, and although it was previously shown that MERS-CoV S can be activated by various proteases, the details of the mechanisms of proteolytic activation of fusion are still incompletely characterized. Here, we have uncovered distinctive characteristics of MERS-CoV S. We identify, by bioinformatics and peptide cleavage assays, two cleavage sites for furin, a ubiquitously expressed protease, which are located at the S1/S2 interface and at the S2' position of the S protein. We show that although the S1/S2 site is proteolytically processed by furin during protein biosynthesis, the S2' site is cleaved upon viral entry. MERS-CoV pseudovirion infection was shown to be enhanced by elevated levels of furin expression, and entry could be decreased by furin siRNA silencing. Enhanced furin activity appeared to partially override the low pH-dependent nature of MERS-CoV entry. Inhibition of furin activity was shown to decrease MERS-CoV S-mediated entry, as well as infection by the virus. Overall, we show that MERS-CoV has evolved an unusual two-step furin activation for fusion, suggestive of a role during the process of emergence into the human population. The ability of MERS-CoV to use furin in this manner, along with other proteases, may explain the polytropic nature of the virus.