title: Intrinsic flexibility of West Nile virus protease in solution characterized using small-angle X-ray scattering.
abstract: West Nile virus (WNV) is a mosquito-borne flavivirus with a rapidly expanding global distribution. Infection can cause severe neurological disease and fatality in humans. Efforts are ongoing to develop antiviral drugs that inhibit the WNV protease, a viral enzyme required for polyprotein processing. Unfortunately, little is known about the solution structure of recombinant WNV protease (NS2B-NS3pro) used for antiviral drug discovery and development, although X-ray crystal structures and nuclear magnetic resonance (NMR) studies have provided valuable insights into the interactions between NS2B-NS3pro and peptide-based inhibitors. We completed small-angle X-ray scattering and Fourier transform infrared spectroscopy experiments to determine the solution structure and dynamics of WNV NS2B-NS3pro in the absence of a bound substrate or inhibitor. Importantly, these solution studies suggested that all or most of the NS2B cofactor was highly flexible and formed an ensemble of structures, in contrast to the NS2B tertiary structures observed in crystallographic and NMR studies. The secondary structure of NS2B-NS3pro in solution had high β-content, similar to the secondary structure observed in crystallographic studies. This work provided evidence of the intrinsic flexibility and conformational heterogeneity of the NS2B chain of the WNV protease in the absence of substratelike ligands, which should be considered during antiviral drug discovery and development efforts.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch , Galveston, Texas 77555, United States.
authors.forename: Andrea P
authors.initials: AP
authors.lastname: Garces
authors.forename: Stanley J
authors.initials: SJ
authors.lastname: Watowich
mesh_terms: D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D018583:Pliability; D020365:RNA Helicases / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D053838:Scattering, Small Angle; D012697:Serine Endopeptidases / Q000737:chemistry; D012996:Solutions; D017361:Viral Nonstructural Proteins / Q000737:chemistry*; D014902:West Nile virus / Q000201:enzymology*; D014961:X-Ray Diffraction; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D020365:RNA Helicases; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D012996:Solutions; D017361:Viral Nonstructural Proteins; C080102:NS2B protein, flavivirus; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases