The role of electrostatic interactions in the formation of bacteriophage MS2 capsid protein shells*

Self-assembly is a vital part in the formation of the capsid protein around viral RNA in small icosahedral viruses. This assembly process also occurs in vitro indicating viral capsid assembly may be driven by free energy minimization. To further understand how non-specific interactions such as electrostatic forces drive capsid formation, we study the assembly of bacteriophage MS2 coat-proteins around MS2 RNA and wild-type bacteriophage MS2 at varying ionic strengths. We use gel electrophoresis, dynamic light scattering, and transmission electron microscopy, to determine the composition, size distribution, and morphology of the assembled structures. In addition, we use zeta potential measurements to determine the overall charge away from the surface. We show that MS2 VLPs vary in morphology as we vary ionic strength and have the ability form additional coat-protein shells around wild type MS2. We contribute these results to the impact that electrostatics forces have on capsid assembly.