NSF/MCB-BSF: Revealing the steps and modulators of coronavirus fusion using single-molecule tools

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Infection by many viruses commences with a membrane fusion event between the viral envelope and host cell membrane, which leads to the transfer of the viral genome into the host cell. Typically, this process is mediated by viral fusion proteins. In this project, the coronavirus spike protein is examined. Within spike, the fusion peptide initiates membrane fusion when it inserts into the host membrane. To study this process, single molecular tools and techniques will be developed and used to study the interaction between the fusion peptide with membrane surfaces that mimic different kinds of host cells. The goal is to understand the relationship between fusion peptide sequence and target membranes using complementary techniques that enable examination of this process across scales, from the fusion peptide to the whole virus. With a better understanding of the science behind the chemical features that modulate this critical interaction, new predictions for virus adaptation to new hosts can be made and exploited to block the process. The Broader Impacts of this project include the intrinsic merit of the work as useful information will be gained that can be leveraged for the design of novel antiviral drugs, and to identify chemical rules that inform predictions of host susceptibility to viral entry. Given that major fusion players are highly conserved across the CoV family, these studies will be directly applicable to all CoVs, including those yet to emerge. In addition, training opportunities for graduate students will be provided, along with outreach activities for high school students. For coronavirus, entry into a host cell is mediated by a single glycoprotein protruding from its membrane envelope, called spike (S). A key determinant of the ability of coronavirus to spread is the interaction of S with its target host membrane. 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, consequently enabling the necessary deformations of the membrane that leads to membrane fusion and the delivery of the viral genome into the cell. Thus, understanding chemical coupling of the FP with the host cell at the nanoscale will facilitate the development of strategies to limit those interactions to stop infection, but also to enable predicting the characteristics of emerging strains and the susceptible hosts. The objective of this project is to identify and measure the specific intermolecular interactions responsible for insertion of FP into membranes. Single molecule tools and techniques will be developed, expanded, and used to understand the fundamental chemical code between the host membrane and FP that modulate interactions that control the fusion process. The intellectual merit of this project is discovering the relationship between the host membrane chemistry and amino acid sequence of the FP that drive the molecular scale interactions between virus and host. This project is co-funded by the Cellular Dynamics and Function together with the Molecular Biophyics programs, both in the Division for Molecular and Cellular Biosciences.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.