SARS-CoV-2 N protein coordinates viral particle assembly through multiple domains

Area of Science:

• Virology
• Molecular Biology
• Structural Biology

Background:

• Mutations in the SARS-CoV-2 nucleocapsid (N) protein influence viral replication.
• Mechanisms of selective genomic RNA packaging and viral assembly by the N protein are not well understood.

Purpose of the Study:

• To investigate the role of different domains of the SARS-CoV-2 N protein in viral assembly and RNA packaging.
• To elucidate the interaction between the N protein and the membrane (M) protein during viral budding.

Main Methods:

• Utilized a virus-like particles (VLPs) system to study SARS-CoV-2 N protein function.
• Investigated interactions between N protein domains (NTD, CTD, LKR) and the M protein.
• Assessed the role of the N protein's C-tail in genomic RNA encapsidation.

Main Results:

• The C-terminal domain (CTD) of the N protein is essential for M protein interaction and budding.
• Fused NTD/CTD and LKR/CTD constructs showed RNA-dependent M protein interaction and budding capabilities.
• The C-tail is crucial for efficient genomic RNA packaging, potentially regulated by M protein interactions.
• The N-terminal domain (NTD) is dispensable for virus particle assembly.

Conclusions:

• The CTD-based assembly mechanism is conserved among beta-coronaviruses.
• The dispensability of the NTD suggests an evolutionary adaptation for streamlined viral assembly.
• Findings provide insights into coronavirus assembly and potential antiviral drug targets.