title: Thermodynamics of zinc binding to hepatitis C virus NS3 protease: a folding by binding event.
abstract: The hepatitis C virus (HCV) nonstructural protein 3 (NS3) protease is responsible for the processing of the non-structural region of the viral precursor polyprotein in infected hepatic cells. HCV NS3 is a zinc-dependent serine protease. The zinc ion, which is bound far away from the active site and considered to have a structural role, is essential for the structural integrity of the protein; furthermore, the ion is required for the hydrolytic activity. Consequently, the NS3 zinc binding site has been considered for a long time as a possible target for drug discovery. As a first step towards this goal, the energetics of the NS3-zinc interaction and its effect on the NS3 conformation must be established and discussed. The thermodynamic characterization of zinc binding to NS3 protease by isothermal titration calorimetry and spectroscopy is presented here. Spectroscopic and calorimetric results suggest that a considerable conformational change in the protein is coupled to zinc binding. The energetics of the conformational change is comparable to that of the folding of a protein of similar size. Therefore, zinc binding to NS3 protease can be considered as a "folding by binding" event.
authors.affiliation: Institute of Biocomputation and Physics of Complex Systems (BIFI), Universidad de Zaragoza, Zaragoza 50009, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Abian
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Neira
authors.forename: Adrian
authors.initials: A
authors.lastname: Velazquez-Campoy
mesh_terms: D001665:Binding Sites; D002151:Calorimetry / Q000379:methods; D030562:Databases, Protein; D006868:Hydrolysis; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D011485:Protein Binding; D017510:Protein Folding; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013816:Thermodynamics; D017361:Viral Nonstructural Proteins / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D008024:Ligands; D017361:Viral Nonstructural Proteins; D015032:Zinc; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases