title: Energetics of RNA binding by the West Nile virus RNA triphosphatase.
abstract: The West Nile virus (WNV) RNA genome harbors the characteristic methylated cap structure present at the 5' end of eukaryotic mRNAs. In the present study, we report a detailed study of the binding energetics and thermodynamic parameters involved in the interaction between RNA and the WNV RNA triphosphatase, an enzyme involved in the synthesis of the RNA cap structure. Fluorescence spectroscopy assays revealed that the initial interaction between RNA and the enzyme is characterized by a high enthalpy of association and that the minimal RNA binding site of NS3 is 13 nucleotides. In order to provide insight into the relationship between the enzyme structure and RNA binding, we also correlated the effect of RNA binding on protein structure using both circular dichroism and denaturation studies as structural indicators. Our data indicate that the protein undergoes structural modifications upon RNA binding, although the interaction does not significantly modify the stability of the protein.
authors.affiliation: Département de Biochimie, Faculté de Médecine, Université de Sherbrooke, 3001 12e avenue, Sherbrooke, Québ., Canada J1H 5N4.
authors.forename: Ines
authors.initials: I
authors.lastname: Benzaghou
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bougie
authors.forename: Frédéric
authors.initials: F
authors.lastname: Picard-Jean
authors.forename: Martin
authors.initials: M
authors.lastname: Bisaillon
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002942:Circular Dichroism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012315:RNA Caps / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014902:West Nile virus / Q000235:genetics / Q000378:metabolism; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D017766:Acid Anhydride Hydrolases; D012315:RNA Caps; D020365:RNA Helicases; D012367:RNA, Viral; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C023090:RNA triphosphatase