Khatri Ritika, Lohiya Bharat, Kaur Gurleen, Maithil Vikas, Goswami Abhishek, Sarmadhikari Debapriyo, Asthana Shailendra, Samal Sweety
Translational Health Science & Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana 121001 India.
3 Biotech. 2023 Oct;13(10):323. doi: 10.1007/s13205-023-03749-y. Epub 2023 Aug 30.
The spike (S) glycoprotein of the SARS-CoV-2 virus binds to the host cell receptor and promotes the virus's entry into the target host cell. This interaction is primed by host cell proteases like furin and TMPRSS2, which act at the S1/S2 and S2´ cleavage sites, respectively. Both cleavage sites have serine or proline residues flanking either the single or polybasic region and were found to be conserved in coronaviruses. Unravelling the effects of these conserved residues on the virus entry and infectivity might facilitate the development of novel therapeutics. Here, we have investigated the role of the conserved serine and proline residues in the SARS-CoV-2 spike mediated entry, fusogenicity, and viral infectivity by using the HIV-1/spike-based pseudovirus system. A conserved serine residue mutation to alanine (S2´S-A) at the S2´ cleavage site resulted in the complete loss of spike cleavage. Exogenous treatment with trypsin or overexpression of TMPRSS2 protease could not rescue the loss of spike cleavage and biological activity. The S2´S-A mutant showed no significant responses against E-64d, TMPRSS2 or other relevant inhibitors. Taken together, serine at the S2´ site in the spike protein was indispensable for spike protein cleavage and virus infectivity. Thus, novel interventions targeting the conserved serine at the S2´ cleavage site should be explored to reduce severe disease caused by SARS-CoV-2-and novel emerging variants.
The online version contains supplementary material available at 10.1007/s13205-023-03749-y.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）病毒的刺突（S）糖蛋白与宿主细胞受体结合，并促进病毒进入靶宿主细胞。这种相互作用由宿主细胞蛋白酶如弗林蛋白酶和跨膜丝氨酸蛋白酶2（TMPRSS2）引发，它们分别作用于S1/S2和S2´裂解位点。两个裂解位点在单个或多碱性区域两侧都有丝氨酸或脯氨酸残基，并且在冠状病毒中被发现是保守的。阐明这些保守残基对病毒进入和感染性的影响可能有助于开发新型治疗方法。在这里，我们通过使用基于HIV-1/刺突的假病毒系统，研究了SARS-CoV-2刺突介导的进入、融合性和病毒感染性中保守丝氨酸和脯氨酸残基的作用。S2´裂解位点处保守的丝氨酸残基突变为丙氨酸（S2´S-A）导致刺突裂解完全丧失。用胰蛋白酶进行外源处理或过表达TMPRSS2蛋白酶均不能挽救刺突裂解和生物活性的丧失。S2´S-A突变体对E-64d、TMPRSS2或其他相关抑制剂没有显著反应。综上所述，刺突蛋白中S2´位点的丝氨酸对于刺突蛋白裂解和病毒感染性是不可或缺的。因此，应探索针对S2´裂解位点保守丝氨酸的新型干预措施，以减少由SARS-CoV-2及其新出现的变异株引起的严重疾病。
在线版本包含可在10.1007/s13205-023-03749-y获取的补充材料。
