RAPID: Revealing the intermolecular interactions between the SARS-CoV-2/COVID-19 fusion peptide and the host cell membrane that underlie its flexibility in host tropism

冠状病毒是一种被膜包裹的包裹，上面装饰着从其表面突出的“尖刺”。这些刺激物与宿主细胞相互作用，启动对该细胞的感染。冠状病毒传播到其他细胞的能力取决于尖峰与其目标宿主膜相互作用的程度。控制这种相互作用的尖峰部分被称为“融合肽”，它的工作是插入宿主膜，开始将其基因货物运送到细胞中。然而，关于融合肽如何与膜相互作用的细节仍不清楚。在这个项目中，将研究融合多肽与模仿不同类型宿主细胞的膜表面之间的各种相互作用。这些信息将提供对融合肽和促进它们相互作用的宿主细胞的特征的洞察，最终，感染和病毒传播到新的宿主。随着对病毒适应新宿主的这种关键相互作用背后的科学有了更好的了解，我们将更好地了解这种病毒是如何传播的，并最终具备制定阻止它的策略的能力。这些基本信息有可能使设计针对融合肽的抗病毒药物的新方法成为可能。鉴于融合多肽在冠状病毒家族中高度保守，这些研究将直接适用于所有冠状病毒，包括引起COVID-19的冠状病毒。冠状病毒传播能力的关键决定因素是它与目标宿主膜的相互作用。对于冠状病毒来说，进入宿主细胞是由从其膜被膜突出的单一糖蛋白介导的，称为刺突(S)。在S体内，直接与膜相互作用的区域称为融合肽，Fp。正是FP与宿主膜的物理化学作用将其锚定，从而使膜发生必要的变形，从而将病毒基因组输送到细胞中。因此，在最基本的水平上了解FP相互作用将有助于制定限制这些相互作用以阻止感染传播的战略。预计这些信息将有助于预测未来可能对人类构成威胁的新出现菌株的特征。本项目的目标是测量和确定导致FP插入膜的特定分子间相互作用。具体地说，本项目将：1)通过原子力显微镜的单分子力测量和生物膜模型来阐明控制FP疏水相互作用的因素，以及2)使用圆二色谱和等温量热法表征FP的结构-功能关系，以将特定的相互作用与氨基酸序列和宿主表面属性相关联。这个项目的智力价值在于发现宿主膜化学或FP氨基酸序列的变化如何调节疏水相互作用，并最终影响对感染传播至关重要的活动。该项目的更广泛影响是提供信息，使抗病毒药物的设计能够采用新的方法，并确定基本设计规则，告知FP如何促进与特定化学物质的膜的相互作用，以预测宿主对感染的易感性。鉴于FP在CoV家族中是高度保守的，这些研究将直接适用于所有CoV，包括那些尚未出现的CoV。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Coronavirus is a membrane-enveloped package decorated with “spikes” that protrude from its surface. These spikes interact with the host cell to initiate infection of that cell. The ability of coronavirus to spread to other cells depends on how well the spike interacts with its target host membrane. The part of the spike that controls this interaction is called the “fusion peptide” and its job is to insert into the host membrane to initiate the delivery its genetic cargo into the cell. However, the specifics of how the fusion peptide interacts with the membrane is still not known. In this project, various interactions between the fusion peptide with membrane surfaces that mimic different kinds of host cells will be studied. This information will provide insight into the characteristics of both the fusion peptide and the host cell that promotes their interaction, and ultimately, infection and viral transmission to new hosts. With a better understanding of the science behind this critical interaction for virus adaptation to new hosts, we will be better informed about how this virus spreads and ultimately equipped to develop strategies to stop it. This fundamental information has the potential to enable fresh approaches to the design of antiviral drugs that target the fusion peptide. Given that the fusion peptide is highly conserved across the coronavirus family, these studies will be directly applicable to all coronaviruses, including the coronavirus that causes COVID-19.A key determinant of the ability of coronavirus to spread is how it interacts with its target host membrane. For coronavirus, entry into a host cell is mediated by a single glycoprotein protruding from its membrane envelope, called spike (S). Within S, the region that directly interacts with the membrane is called the fusion peptide, FP. It is the physico-chemical interactions of the FP with the host membrane that anchors it, thus enabling the necessary deformations of the membrane that lead to delivery of the viral genome into the cell. Thus, understanding FP interactions at the most fundamental level will facilitate the development of strategies to limit those interactions to stop the spread of infections. This information is expected to be helpful in predicting the characteristics of emerging strains that could post a threat to humans in the future. The objective of this project is to measure and identify the specific intermolecular interactions responsible for insertion of FP into membranes. Specifically, this project will: 1) elucidate the factors that control hydrophobic interactions of FP using single molecule force measurements with atomic force microscopy and models of biological membranes, and 2) characterize the structure-function relationship of the FP using circular dichroism and isothermal calorimetry to correlate specific interactions with amino acid sequence and host surface properties. The intellectual merit of this project is discovering how changes in host membrane chemistry or amino acid sequence of the FP modulates the hydrophobic interaction and ultimately influences activity critical to the spread of infection. The broader impact of this project is providing information that will enable fresh approaches to the design of antiviral drugs, as well as to identify basic design rules that inform how the FP promotes the interaction with membranes of specific chemistry to predict host susceptibility to infection. Given that the FP is highly conserved across the CoV family, these studies will be directly applicable to all CoVs, including those yet to emerge.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.