Forum 01/30/2009

“Single-Particle EM Structural Analysis of the Rotavirus Virion at Near-Atomic Resolution”

James Chen – Brandeis University

Rotavirus is a non-enveloped, icosahedral, double-strand RNA virus that is a major cause of gastroenteritis in children. The infectious viral capsid is composed of four structural proteins arranged in three layers: VP4 and VP7 in the outer layer, VP6 in the middle layer, and VP2 in the inner layer. Using electron cryo-microscopy (cryo-EM) and single-particle reconstruction, we have determined the structure of a double-layer particle (genome encapsidated by VP2 +VP6) coated with outer-layer protein VP7. At about 4 Å resolution, the structure reveals most of the polypeptide path of VP7, and enables de novo modeling of its N-terminus, which closely interacts with VP6. We were able to detect conformational differences in the bound VP7 and the double-layer rotavirus particle (DLP) compared with the structure to the recently determined crystal structure of VP7 and the cryo-EM structure of the DLP, respectively. The observed differences suggest structural changes in the virus particle necessary for RNA release during viral infection.