Screen for Modulation of Nucleocapsid Protein Condensation Identifies Small Molecules with Anti-Coronavirus Activity

Area of Science:

• Biochemistry
• Virology
• Drug Discovery

Background:

• Biomolecular condensates, formed by liquid-liquid phase separation, are linked to diseases.
• Modulating condensate dynamics with small molecules offers therapeutic possibilities.
• The SARS-CoV-2 nucleocapsid (N) protein forms phase-separated condensates crucial for viral replication.

Purpose of the Study:

• To investigate the phase separation tendencies of nucleocapsid proteins from all seven human coronaviruses (HCoVs).
• To identify small molecules that modulate the condensation of SARS-CoV-2 N protein.
• To explore the therapeutic potential of identified condensate modulators against various HCoVs.

Main Methods:

• Expression of HCoV N proteins in human lung epithelial cells.
• Development of a cell-based high-content screening platform.
• Identification and characterization of small molecules affecting N protein condensation.

Main Results:

• N proteins from all seven HCoVs exhibit varying phase separation tendencies.
• Identified small molecules promote or inhibit SARS-CoV-2 N condensation.
• These host-targeted small molecules demonstrated cross-HCoV N condensate-modulatory effects.
• Some identified molecules showed antiviral activity against SARS-CoV-2, HCoV-OC43, and HCoV-229E.

Conclusions:

• Assembly dynamics of viral nucleocapsid condensates can be regulated by small molecules.
• This approach enables rapid drug discovery for coronaviruses based on genomic sequences.
• Identified modulators hold therapeutic potential for combating current and future coronavirus pandemics.