In vitro RNA synthesis from exogenous dengue viral RNA templates requires long range interactions between 5 '- and 3 '-terminal regions that influence RNA structure
Sy. You et al., In vitro RNA synthesis from exogenous dengue viral RNA templates requires long range interactions between 5 '- and 3 '-terminal regions that influence RNA structure, J BIOL CHEM, 276(19), 2001, pp. 15581-15591
Viral replicases of many positive-strand RNA viruses are membrane-bound com
plexes of cellular and viral proteins that include viral RNA-dependent RNA
polymerase (RdRP). The in vitro RdRP assay system that utilizes cytoplasmic
extracts from dengue viral-infected cells and exogenous RNA templates was
developed to understand the mechanism of viral replication in vivo. Our res
ults indicated that in vitro RNA synthesis at the 5'-untranslated region (U
TR) required the presence of the 5'-terminal region (TR) and the two cycliz
ation (CYC) motifs suggesting a functional interaction between the TRs. In
this study, using a psoralen-UV crosslinking method and an in vitro RdRP as
say, we analyzed structural determinants for physical and functional intera
ctions. Exogenous RNA templates that were used in the assays contained dele
tion mutations in the 5'-TR and substitution mutations in the 3'-stem-loop
structure including those that would disrupt the predicted pseudoknot struc
ture. Our results indicate that there is physical interaction between the 5
'-TR and 3'-UTR that requires only the CYC motifs. RNA synthesis at the 3'-
UTR, however, requires long range interactions involving the 5'-UTR, CYC mo
tifs, and the 3'-stem-loop region that includes the tertiary pseudoknot str
ucture.