Theoretical Physics and Center of Interdisciplinary Nanostructure Science and Technology, FB10, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany.
CONICET Consejo Nacional de Investigaciones Científicas y Técnicas, Godoy Cruz 2290, Buenos Aires C1425FQB, Argentina.
Viruses. 2023 Dec 11;15(12):2405. doi: 10.3390/v15122405.
In its prefusion state, the SARS-CoV-2 spike protein (similarly to other class I viral fusion proteins) is metastable, which is considered to be an important feature for optimizing or regulating its functions. After the binding process of its S1 subunit (S1) with ACE2, the spike protein (S) undergoes a dramatic conformational change where S1 splits from the S2 subunit, which then penetrates the membrane of the host cell, promoting the fusion of the viral and cell membranes. This results in the infection of the host cell. In a previous work, we showed-using large-scale molecular dynamics simulations-that the application of external electric fields (EFs) induces drastic changes and damage in the receptor-binding domain (RBD) of the wild-type spike protein, as well of the Alpha, Beta, and Gamma variants, leaving a structure which cannot be recognized anymore by ACE2. In this work, we first extend the study to the Delta and Omicron variants and confirm the high sensitivity and extreme vulnerability of the RBD of the prefusion state of S to moderate EF (as weak as 10 V/m), but, more importantly, we also show that, in contrast, the S2 subunit of the postfusion state of the spike protein does not suffer structural damage even if electric field intensities four orders of magnitude higher are applied. These results provide a solid scientific basis to confirm the connection between the prefusion-state metastability of the SARS-CoV-2 spike protein and its susceptibility to be damaged by EF. After the virus docks to the ACE2 receptor, the stable and robust postfusion conformation develops, which exhibits a similar resistance to EF (damage threshold higher than 10 V/m) like most globular proteins.
在其预融合状态下，SARS-CoV-2 刺突蛋白（与其他 I 类病毒融合蛋白类似）是亚稳态的，这被认为是优化或调节其功能的重要特征。在其 S1 亚基（S1）与 ACE2 结合后，刺突蛋白（S）经历剧烈的构象变化，其中 S1 从 S2 亚基中分裂，然后穿透宿主细胞的膜，促进病毒和细胞膜的融合。这导致宿主细胞感染。在之前的工作中，我们使用大规模分子动力学模拟表明，外部电场（EF）的应用会导致野生型刺突蛋白的受体结合域（RBD）以及 Alpha、Beta 和 Gamma 变体发生剧烈变化和损伤，使结构无法再被 ACE2 识别。在这项工作中，我们首先将研究扩展到 Delta 和 Omicron 变体，并证实了预融合状态的 RBD 对中等 EF（弱至 10 V/m）非常敏感和极其脆弱，但更重要的是，我们还表明，相比之下，即使施加高四个数量级的电场强度，融合后状态的刺突蛋白的 S2 亚基也不会遭受结构损伤。这些结果为确认 SARS-CoV-2 刺突蛋白预融合状态的亚稳性与其对 EF 损伤的易感性之间的联系提供了坚实的科学依据。病毒与 ACE2 受体对接后，会形成稳定且坚固的融合后构象，表现出类似于大多数球状蛋白的对 EF 的类似抗性（损伤阈值高于 10 V/m）。
