Probing SARS-CoV-2 membrane binding peptide via single-molecule AFM-based force spectroscopy.

Area of Science:

• Virology
• Structural Biology
• Biochemistry

Background:

• The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein mediates viral entry by fusing with host cell membranes.
• A membrane-binding peptide (MBP) near the TMPRSS2 cleavage site is crucial for this process.
• Understanding the MBP's interaction with host membranes is key to identifying viral entry mechanisms.

Purpose of the Study:

• To investigate the interaction of the SARS-CoV-2 spike protein's MBP with host cell membranes.
• To determine the role of membrane composition, specifically cholesterol, in viral entry.
• To elucidate the structural contribution of the MBP's disulfide bridge to membrane binding and viral infectivity.

Main Methods:

• In vitro binding assays to study MBP-membrane interactions.
• Computational modeling to analyze peptide-membrane dynamics.
• Cholesterol depletion experiments to assess its impact on viral infectivity.
• Analysis of both primed (TMPRSS2-cleaved) and unprimed MBP variants.

Main Results:

• The MBP preferentially binds to cholesterol-rich membranes.
• Cholesterol depletion significantly reduces SARS-CoV-2 infectivity.
• The conserved disulfide bridge within the MBP stabilizes its membrane interaction.
• The disulfide bridge plays a structural role in facilitating viral entry.

Conclusions:

• Host cell membrane cholesterol content is critical for SARS-CoV-2 infectivity.
• The MBP's disulfide bridge is a key structural element for membrane binding and viral entry.
• Targeting the MBP disulfide bridge represents a potential therapeutic strategy to inhibit SARS-CoV-2 infection.