Structure of the Murray Valley encephalitis virus RNA helicase at 1.9 Angstrom resolution.

Murray Valley encephalitis virus (MVEV), a mosquito-borne flavivirus endemic to Australia, is closely related to Japanese encephalitis virus and West Nile virus. Nonstructural protein 3 (NS3) is a multifunctional enzyme with serine protease and DEXH/D-box helicase domains, whose activity is central to flavivirus replication and is therefore a possible target for anti-flaviviral compounds. Cloning, purification, and crystal structure determination to 1.9 Angstrom resolution of the NS3 helicase of MVEV and characterization of its enzymatic activity is reported. Comparison with the structures of helicases from related viruses supports a possible mechanism of ATP hydrolysis-driven strand separation.