Dengue virus strain 2 capsid protein switches the annealing pathway and reduces intrinsic dynamics of the conserved 5' untranslated region.

The capsid protein of dengue virus strain 2 (DENV2C) promotes nucleic acid structural rearrangements using chaperone activity. However, the role of DENV2C during the interaction of RNA elements in the conserved 5' untranslated region (5'UTR) to the 3' untranslated region (3'UTR) is still unclear. Thus, we investigated the effect of DENV2C on the annealing mechanism of two RNA hairpin elements from the 5'UTR to their complementary sequences during (+)/(-) ds-RNAformation and (+) RNA circularization. DENV2C was found to switch the annealing pathway for RNA elements involved in (+)/(-) ds-RNA formation, but not for RNA elements related to (+) RNA circularization. In addition, we also determined that DENV2C modulates intrinsic dynamics and reduces kinetically trapped unfavourable conformations of the 5'UTR sequence. Thus, our results provide mechanistic insights by which DENV2C chaperones the interactions between RNA elements at the 5' and 3' ends during genome recombination, a prerequisite for DENV replication.