Characterization of rotavirus NSP2/NSP5 interactions and the dynamics of viroplasm formation

• DOI: 10.1099/vir.0.19611-0
• Publication Date: 2004-03-01T11:12:50Z
• Authors: Catherine Eichwald; José Francisco Ro...; Oscar R. Burrone
• Keywords: Mammals; Rotavirus; 0303 health sciences; Microscopy, Confocal; Base Sequence; Recombinant Fusion Proteins; Green Fluorescent Proteins; RNA-Binding Proteins; Viral Nonstructural Proteins; Transfection; Cell Line; 3. Good health; Luminescent Proteins; Viral Proteins; 03 medical and health sciences; Genes, Reporter; Animals; DNA Primers

Viroplasms are discrete structures formed in the cytoplasm of rotavirus-infected cells and constitute the replication machinery of the virus. The non-structural proteins NSP2 and NSP5 localize in viroplasms together with other viral proteins, including the polymerase VP1, VP3 and the main inner-core protein, VP2. NSP2 and NSP5 interact with each other, activating NSP5 hyperphosphorylation and the formation of viroplasm-like structures (VLSs). We have used NSP2 and NSP5 fused to the enhanced green fluorescent protein (EGFP) to investigate the localization of both proteins within viroplasms in virus-infected cells, as well as the dynamics of viroplasm formation. The number of viroplasms was shown first to increase and then to decrease with time post-infection, while the area of each one increased, suggesting the occurrence of fusions. The interaction between NSP2 and a series of NSP5 mutants was investigated using two different assays, a yeast two-hybrid system and an in vivo binding/immunoprecipitation assay. Both methods gave comparable results, indicating that the N-terminal region (33 aa) as well as the C-terminal part (aa 131-198) of NSP5 are required for binding to NSP2. When fused to the N and C terminus of EGFP, respectively, these two regions were able to confer the ability to localize in the viroplasm and to form VLSs with NSP2.