SARS-CoV-2 Envelope Protein Forms Clustered Pentamers in Lipid Bilayers

Area of Science:

• Structural biology
• Virology
• Biophysics

Background:

• The SARS-CoV-2 envelope (E) protein is a viroporin linked to COVID-19 symptoms.
• E protein forms ion channels in cellular membranes, influencing host inflammatory responses.
• Previous studies on E protein oligomerization yielded inconclusive results regarding its stoichiometry.

Purpose of the Study:

• To determine the oligomeric number of the SARS-CoV-2 E protein's transmembrane domain (ETM).
• To investigate the supramolecular organization of ETM in lipid bilayers.
• To elucidate the functional implications of ETM's assembly and clustering.

Main Methods:

• Utilized ¹⁹F solid-state nuclear magnetic resonance (ssNMR).
• Employed the centerband-only detection of exchange (CODEX) technique.
• Performed Monte Carlo simulations incorporating peptide-peptide and peptide-lipid interactions.

Main Results:

• ETM assembles into stable pentamers in lipid bilayers.
• ETM pentamers exhibit clustering at high peptide concentrations, particularly with phosphatidylinositol.
• Simulations successfully reproduced the observed clustering, supporting a supramolecular organization.

Conclusions:

• The SARS-CoV-2 ETM forms pentameric units that further associate into clusters within lipid bilayers.
• This higher-order organization is likely vital for viral assembly, budding, and ion channel function.
• Findings provide critical insights into the structural basis of E protein's role in SARS-CoV-2 pathogenesis.