Two-Dimensional Crystallization of P22 Virus-Like Particles.

Area of Science:

• Biomaterials Science
• Structural Biology
• Nanotechnology

Background:

• Virus-like particles (VLPs) are versatile platforms for biomimetic materials.
• Bacteriophage P22 VLPs can encapsulate enzymes and self-assemble into ordered structures.

Purpose of the Study:

• To develop methods for fabricating densely packed 2D monolayers of P22 VLPs.
• To utilize these ordered assemblies as 2D crystals for electron crystallography.

Main Methods:

• 2D crystallization of various P22 VLP morphologies (procapsid, empty shell, expanded form) on a positively charged lipid monolayer at the water-air interface.
• Transfer of the lipid monolayer with adsorbed VLPs to a carbon grid for electron microscopy.
• Optimization of subphase conditions (trehalose, NaCl, MES buffer) for crystal formation.

Main Results:

• Successfully formed 2D crystals of different P22 VLP forms, including enzyme-encapsulated variants.
• Achieved ordered assemblies with diffraction spots extending to the sixth order (negative stain) and tenth order (cryo-EM).
• Demonstrated the feasibility of using P22 VLPs for high-resolution structural analysis via electron crystallography.

Conclusions:

• Established a robust method for 2D crystallization of P22 VLPs.
• These ordered VLP assemblies are suitable for advanced structural studies and potential applications in functional biomimetic membranes.