Self-assembly of severe acute respiratory syndrome coronavirus membrane protein

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• The coronavirus membrane (M) protein is crucial for virion assembly, often forming virus-like particles (VLPs) with other viral proteins.
• Understanding M protein's self-assembly and localization is key to deciphering SARS-CoV assembly mechanisms.

Purpose of the Study:

• To investigate the self-assembly, release, and subcellular localization of the severe acute respiratory syndrome coronavirus (SARS-CoV) M protein.
• To identify regions of the M protein involved in its assembly and localization.

Main Methods:

• Coexpression of SARS-CoV M protein with N or E proteins.
• Analysis of M protein self-assembly and release in medium.
• Cellular localization studies using various cell types.
• Genetic analysis involving M protein fusion proteins and domain deletions.
• Investigation of RNA independence and glycosylation effects.

Main Results:

• SARS-CoV M protein self-assembles and is released in membrane-enveloped vesicles, independent of RNA.
• M protein localizes to the Golgi area and plasma membranes.
• Blocking M glycosylation did not significantly impact M localization or VLP formation.
• The third transmembrane domain is involved in plasma membrane targeting.
• Regions beyond the transmembrane domains also contribute to membrane binding, Golgi retention, and M-M interactions.

Conclusions:

• SARS-CoV M protein possesses intrinsic self-assembly properties independent of RNA.
• Multiple regions within the M protein contribute to its complex subcellular localization and self-assembly processes.
• These findings provide insights into the mechanisms of coronavirus assembly and pathogenesis.