Equilibrium self-assembly of small RNA viruses

Area of Science:

• Biophysics
• Structural Biology
• Virology

Background:

• Viral capsid proteins (CPs) often possess disordered tails that interact with the viral RNA genome.
• The self-assembly of viral components is crucial for forming infectious virions.
• Existing self-assembly theories primarily address empty capsid formation, not RNA-encapsidating viruses.

Purpose of the Study:

• To propose a novel description for the quasiequilibrium self-assembly of single-stranded RNA viruses.
• To model the interplay between capsid protein assembly and viral RNA condensation.
• To investigate the applicability of conventional self-assembly theories to RNA-containing virions.

Main Methods:

• Developed a theoretical framework describing viral assembly as coupled phase-transition-like events.
• Analyzed the roles of electrostatic repulsion, hydrophobic interactions, and tail-mediated RNA neutralization.
• Derived an assembly diagram based on interaction strengths between CPs and RNA.

Main Results:

• Viral assembly is characterized by the coupled processes of capsid formation and RNA condensation.
• Electrostatic and hydrophobic forces, along with tail-RNA interactions, govern the assembly process.
• An assembly diagram illustrates the conditions for successful virion formation.

Conclusions:

• The proposed model provides a more accurate description of RNA virus self-assembly than conventional theories.
• Conventional self-assembly theories are generally insufficient for explaining the assembly of RNA-encapsidating virions.
• Understanding these coupled events is key to deciphering the formation of complex viral structures.