Biophysical Society Conference | Tahoe 2024

Molecular Biophysics of Membranes

Tuesday Speaker Abstracts

EXPLORING THE VITAL ROLE OF THE ANIONIC LIPID IN INITIATING SARS COV-2 FUSION Jinwoo Lee ; 1 University of Maryland, Chemistry and Biochemistry, College Park, MD, USA Membrane fusion is a critical step in the viral lifecycle, enabling the delivery of genetic material into the host cell. For SARS-CoV-2, fusion relies on significant conformational changes within the S2 subunit of the spike glycoprotein. This process begins with a cleavage event at S2’, releasing the fusion domain (FD), which then integrates into the target membrane, disrupting the lipid environment. Thus, the initial interaction between the FD and the lipid membrane of the target cell is crucial for viral fusion. Consequently, a comprehensive understanding of SARS CoV-2 infectivity necessitates investigating the interactions between the FD and the lipid membrane of the target cell, examining both protein and lipid perspectives. Using a FRET-based in vitro fusion assay, we uncovered a clear and distinctive correlation between the fusogenicity of the fusion domain (FD) and the endosome-specific lipid BMP. Comparative analysis with other anionic lipids using various biophysical techniques revealed that BMP exerts a unique influence on lipid packing, which accounts for its specificity. To investigate further from a protein standpoint, we conducted mutagenesis on all positively charged amino acids, employing both alanine and charge-conserving mutants. Our findings indicate that certain amino acids possess distinct functional attributes tailored to anionic lipids, implying direct interactions with their negatively charged headgroups. In summary, the initiation of fusion by the SARS-CoV-2 FD is significantly enhanced in the presence of BMP due to its disruptive effect on lipid packing and the presence of multiple interactions between positively charged residues and the anionic lipid headgroup.

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