Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, United States.
MassBiologics of the University of Massachusetts Chan Medical School, Boston, United States.
Elife. 2022 Mar 24;11:e75433. doi: 10.7554/eLife.75433.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects cells through binding to angiotensin-converting enzyme 2 (ACE2). This interaction is mediated by the receptor-binding domain (RBD) of the viral spike (S) glycoprotein. Structural and dynamic data have shown that S can adopt multiple conformations, which controls the exposure of the ACE2-binding site in the RBD. Here, using single-molecule Förster resonance energy transfer (smFRET) imaging, we report the effects of ACE2 and antibody binding on the conformational dynamics of S from the Wuhan-1 strain and in the presence of the D614G mutation. We find that D614G modulates the energetics of the RBD position in a manner similar to ACE2 binding. We also find that antibodies that target diverse epitopes, including those distal to the RBD, stabilize the RBD in a position competent for ACE2 binding. Parallel solution-based binding experiments using fluorescence correlation spectroscopy (FCS) indicate antibody-mediated enhancement of ACE2 binding. These findings inform on novel strategies for therapeutic antibody cocktails.
严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）通过与血管紧张素转化酶 2（ACE2）结合感染细胞。这种相互作用是由病毒刺突（S）糖蛋白的受体结合域（RBD）介导的。结构和动态数据表明，S 可以采用多种构象，从而控制 RBD 中 ACE2 结合位点的暴露。在这里，我们使用单分子Förster 共振能量转移（smFRET）成像，报告了 ACE2 和抗体结合对来自武汉-1 株的 S 的构象动力学的影响，以及在存在 D614G 突变的情况下的影响。我们发现 D614G 以类似于 ACE2 结合的方式调节 RBD 位置的能量。我们还发现，针对不同表位的抗体，包括远离 RBD 的表位，可将 RBD 稳定在适合 ACE2 结合的位置。使用荧光相关光谱（FCS）的平行溶液结合实验表明，抗体介导了 ACE2 结合的增强。这些发现为治疗性抗体鸡尾酒提供了新的策略信息。
