The crystal structure of bacteriophage Qβ at 3.5 å resolution

Abstract Background: The capsid protein subunits of small RNA bacteriophages form a T=3 particle upon assembly and RNA encapsidation. Dimers of the capsid protein repress translation of the replicase gene product by binding to the ribosome binding site and this interaction is believed to initiate RNA encapsidation. We have determined the crystal structure of phage Qβ with the aim of clarifying which factors are the most important for particle assembly and RNA interaction in the small phages. Results The crystal structure of bacteriophage Qβ determined at 3.5 a resolution shows that the capsid is stabilized by disulfide bonds on each side of the flexible loops that are situated around the fi…