Mutational Analysis of Bovine Viral Diarrhea Virus RNA-Dependent RNA Polymerase
AUTOR(ES)
Lai, Vicky C. H.
FONTE
American Society for Microbiology
RESUMO
Recombinant bovine viral diarrhea virus (BVDV) nonstructural protein 5B (NS5B) produced in insect cells has been shown to possess an RNA-dependent RNA polymerase (RdRp) activity. Our initial attempt to produce the full-length BVDV NS5B with a C-terminal hexahistidine tag in Escherichia coli failed due to the expression of insoluble products. Prompted by a recent report that removal of the C-terminal hydrophobic domain significantly improved the solubility of hepatitis C virus (HCV) NS5B, we constructed a similar deletion of 24 amino acids at the C terminus of BVDV NS5B. The resulting fusion protein, NS5BΔCT24-His, was purified to homogeneity and demonstrated to direct RNA replication via both primer-dependent (elongative) and primer-independent (de novo) mechanisms. Furthermore, BVDV RdRp was found to utilize a circular single-stranded DNA as a template for RNA synthesis, suggesting that synthesis does not require ends in the template. In addition to the previously described polymerase motifs A, B, C, and D, alignments with other flavivirus sequences revealed two additional motifs, one N-terminal to motif A and one C-terminal to motif D. Extensive alanine substitutions showed that while most mutations had similar effects on both elongative and de novo RNA syntheses, some had selective effects. Finally, deletions of up to 90 amino acids from the N terminus did not significantly affect RdRp activities, whereas deletions of more than 24 amino acids at the C terminus resulted in either insoluble products or soluble proteins (ΔCT179 and ΔCT218) that lacked RdRp activities.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=113065Documentos Relacionados
- The structure of the RNA-dependent RNA polymerase from bovine viral diarrhea virus establishes the role of GTP in de novo initiation
- Identification and Characterization of an RNA-Dependent RNA Polymerase Activity within the Nonstructural Protein 5B Region of Bovine Viral Diarrhea Virus
- Influenza A virus RNA-dependent RNA polymerase: analysis of RNA synthesis in vitro.
- Reticulocyte RNA-Dependent RNA Polymerase
- Formation of brome mosaic virus RNA-dependent RNA polymerase in yeast requires coexpression of viral proteins and viral RNA.