ABSTRACT

The binding of the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein onto human angiotensin-converting enzyme 2 (ACE2) is considered as the first step for the virus to adhere onto the host cells during the infection. Here, we investigated the adhesion of spike proteins from different variants and ACE2 using single-molecule and single-cell force spectroscopy. We found that the unbinding force and binding probability of the spike protein from Delta variant to the ACE2 were the highest among the variants tested in our study at both single-molecule and single-cell levels. As the most popular variants, the Omicron variants have slightly higher unbinding force to the ACE2 than wild type. Molecular dynamics simulation showed that ACE2-RBD (Omicron BA.1) complex is destabilized by the E484A and Y505H mutations and stabilized by S477N and N501Y mutations, when compared with Delta variant. In addition, a neutralizing antibody, produced by immunization with wild type spike protein, could effectively inhibit the binding of spike proteins from wild type, Delta and Omicron variants (BA.1 and BA.5) onto ACE2. Our results provide new insight for the molecular mechanism of the adhesive interactions between spike protein and ACE2 and suggest that effective monoclonal antibody can be prepared using wild type spike protein against different variants.

摘要

严重急性呼吸综合征冠状病毒2（SARS-CoV-2）刺突蛋白的受体结合域（RBD）与人血管紧张素转换酶2（ACE2）的结合被认为是病毒粘附到宿主上的第一步细胞在感染过程中。在这里，我们使用单分子和单细胞力谱研究了来自不同变体的刺突蛋白和 ACE2 的粘附。我们发现，在我们研究的单分子和单细胞水平上测试的变体中，Delta 变体的刺突蛋白与 ACE2 的解离力和结合概率最高。作为最流行的变体，Omicron 变体对 ACE2 的解绑力略高于野生型。分子动力学模拟表明，与 Delta 变体相比，ACE2-RBD (Omicron BA.1) 复合物因 E484A 和 Y505H 突变而不稳定，并因 S477N 和 N501Y 突变而稳定。此外，用野生型刺突蛋白免疫产生的中和抗体可以有效抑制野生型、Delta 和 Omicron 变体（BA.1 和 BA.5）的刺突蛋白与 ACE2 的结合。我们的结果为刺突蛋白和 ACE2 之间粘附相互作用的分子机制提供了新的见解，并表明可以使用野生型刺突蛋白针对不同变体制备有效的单克隆抗体。