CAREER: The Lassa Virus Fusion Domain - A Cyclic Approach to Revealing the Molecular Chemistry behind Membrane Fusion

With the support of the CLP program in the Division of Chemistry, Jin Woo Lee from the University of Maryland, College Park is studying the molecular chemistry behind the initiation of Lassa Virus (LASV) membrane fusion. LASV is a member of the Arenavirus family that is currently endemic to West Africa, and there is an increasing incidence of LASV infection reported worldwide. The pandemic potential of LASV has already been noted by the World Health Organization (WHO) in 2018, which stated that the virus requires urgent and prioritized research. Membrane fusion is a key component of the LASV lifecycle that allows the virus to deliver its genetic information into the target cell through a chemical process that is not well understood. The process is thought to be facilitated by specialized fusion machinery that undergoes structural transitions triggered by specific environmental conditions. One such example of this machinery is the fusion domain (FD), which is predominately associated with the initiation of membrane fusion. The research aims to identify, on a molecular level, exactly how the FD initiates the process of membrane fusion. Such information is often a prerequisite for novel therapeutic design that may serve to arrest the viral lifecycle and prevent and/or treat LASV infection. Simultaneously, an educational outreach program will be implemented focused on providing opportunities for incoming transfer students as well as local high school students to gain practical scientific research experience. The aim of the program is to improve both the retention and enrollment of students within the science, technology, engineering, and mathematics (STEM) fields. The initiation of LASV membrane fusion relies on the FD, which resides within the viral glycoprotein found on the viral surface. This domain is well conserved across the Arenavirus family and is also structurally distinct, containing both an N-terminal fusion peptide (FP) and an internal fusion loop (FL). The overarching goal of the research is to understand how the underlying chemistry of the FD contributes to the initiation of membrane fusion. Specifically, the structural and functional roles of multiple fusogenic regions within the LASV FD and the impacts of environmental conditions will be examined. A cyclic approach will be employed utilizing solution nuclear magnetic resonance (NMR) spectroscopy to elucidate the structural rearrangement of the LASV FD. The NMR work will be complemented by thermodynamic and kinetic investigations through isothermal titration calorimetry (ITC) and in vitro lipid mixing fusion assays. The framework mentioned allows the investigation of the FD as both a peptide and within the context of the full viral glycoprotein. The latter requires a novel approach involving specific labeling and incorporation into a lipid bilayer, both of which will be implemented in order to provide more physiological relevance. Upon conclusion of the research, a major knowledge gap regarding LASV membrane fusion will be filled and a framework for studying other viral FDs will be established. 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.