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Study of SARS-CoV-2 Membrane Protein Conformation and Assembly in the ERGIC Bilayer and its Implications in the Virus Budding Process

ORAL

Abstract

Coronaviruses have triggered significant health crises and economic challenges throughout history. Although the pandemic subsides, research on SARS-CoV-2 virus assembly remains crucial, as understanding the virus’s assembly mechanisms can aid in the development of more effective antiviral therapeutics. The SARS-CoV-2 membrane (M) protein, being the most abundant structural protein in the virus, plays a central role in the viral assembly and budding process. Despite the significant functions of M protein, specific understanding on a molecular level is still lacking in their assembly in the lipid bilayer membrane and interactions with other structural proteins, as well as the specific budding conditions. In this study, M protein was expressed, purified and reconstituted into unilamellar vesicles with ERGIC lipid composition and characterized with atomic force microscopy (AFM), cryo-electron microscopy (cryo-EM) and confocal microscopy. At low M protein concentrations, in-situ AFM showed that reconstituted M protein exists mainly in the short form in the ERGIC-mimic bilayer membrane, forming island-like 2D aggregations with increased reconstituted concentration. The ERGIC-mimic membrane demonstrated thinning behavior around the reconstituted M proteins due to hydrophobic mismatch and was validated by molecular dynamic simulations. Cryo-EM revealed that the proteins were uni-directionally reconstituted with the C-terminal facing the interior of the vesicles. The M proteins were also reconstituted, at high concentrations, into giant unilamellar vesicles (GUV). We found, through confocal microscopy, that M protein disrupts the GUV membrane curvature above a critical reconstituted concentration, resulting in the deviation of GUV from their original spherical form towards anisotropic tube-like structures. The insights gained from this study help elucidate the function of M protein in the viral budding process and inform new endeavors to disrupt the coronavirus formation.

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Publication: https://www.science.org/doi/epdf/10.1126/sciadv.adm7030

Presenters

  • Yuanzhong Zhang

    University of California Riverside, University of California, Riverside

Authors

  • Yuanzhong Zhang

    University of California Riverside, University of California, Riverside

  • sara anbir

    University of California, Riverside

  • Joseph McTiernan

    University of California, Merced

  • Siyu Li

    University of California, Riverside, California State Polytechnic University, Pomona

  • Michael Worcester

    University of California, Riverside

  • Pratyasha Mishra

    University of California Riverside, University of California, Riverside

  • Michael E Colvin

    University of California, Merced, University of California Merced

  • Ajay Gopinathan

    University of California, Merced, Dept. of Physics, UC Merced, Department of Physics, University of California, Merced

  • Thomas E Kuhlman

    University of California, Riverside

  • Roya Zandi

    University of California, Riverside

  • Umar Mohideen

    University of California Riverside, University of California, Riverside