SARS-CoV-2 nucleocapsid protein delays cell cycle in S-phase

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused a global health crisis.
• SARS-CoV-2 infection interferes with host cell S phase progression.
• The nucleocapsid (N) protein is abundant and present early in infection.

Purpose of the Study:

• To investigate the role of the SARS-CoV-2 N protein in host cell cycle regulation.
• To determine the specific effects of the N protein on cell cycle progression and cell growth.

Main Methods:

• Analysis of SARS-CoV-2 N protein's effect on S phase entry and exit.
• Assessment of cell proliferation and cell death following N protein expression.
• Site-directed mutagenesis to identify functional domains of the N protein (N-arm, SR-rich region, CTD, C-tail, NTD).

Main Results:

• SARS-CoV-2 N protein induces S phase arrest by promoting entry and blocking exit.
• N protein curtails cell proliferation and slows cell growth without inducing cell death.
• Deletion of N-arm, SR-rich region, CTD, or C-tail abolishes growth suppression; NTD deletion does not.

Conclusions:

• The SARS-CoV-2 N protein modulates host cell cycle progression and growth.
• The N protein plays a multifunctional role in viral replication and host cell physiology.
• Specific domains of the N protein are critical for its effects on cell cycle and growth.