A novel viral RNA helicase with an independent translation enhancement activity

RNA helicases have not been identified among negative sense RNA viruses. In this study, it is shown that Nonstructural protein (NSs) of Groundnut bud necrosis virus (GBNV) acts as a Mg2+- and ATP-dependent bipolar RNA helicase. Biophysical and biochemical analysis of the deletion mutants (N Delta 124 NSs, C Delta 80 NSs) revealed that both the N- and C-terminal residues are required for substrate binding, oligomerization and helicase activity, but are dispensable for ATPase activity. Interestingly, NSs could enhance the translation of RNA (similar to 10-fold) independent of its helicase activity. This is the first report of a RNA helicase from negative strand RNA viruses.