Many paths, similar destinations: viruses and bacterial microcompartments form polyhedra inside cells

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• Icosahedral structures, including viral capsids and bacterial microcompartments, are common in nature.
• These structures are assembled from pentameric and hexameric protein subunits.
• Both viral capsids and bacterial microcompartments exhibit deviations from strict icosahedral symmetry.

Purpose of the Study:

• To review shared principles and distinctions in the self-assembly of icosahedral and polyhedral protein cages.
• To explore how cargo influences the assembly pathways and final morphology of these structures.
• To understand the diversity of protein cage architectures in biological systems.

Main Methods:

• Comparative analysis of viral capsids and bacterial microcompartments.
• Review of existing literature on protein self-assembly.
• Exploration of structure-function relationships in protein cages.

Main Results:

• Identified common assembly principles for icosahedral protein cages, such as viral capsids and bacterial microcompartments.
• Highlighted key distinctions related to cargo encapsulation (nucleic acid vs. protein) and symmetry variations.
• Demonstrated that diverse polyhedral structures are common in bacterial microcompartments, unlike most viruses.

Conclusions:

• Shared principles govern the self-assembly of diverse icosahedral and polyhedral protein cages.
• Cargo type significantly influences the assembly pathways and resulting protein cage morphology.
• Multiple evolutionary paths can lead to similar protein cage structures, showcasing adaptive self-assembly.