title: Binding of a noncovalent inhibitor exploiting the S' region stabilizes the hepatitis C virus NS3 protease conformation in the absence of cofactor.
abstract: We present the first structure of a noncovalent inhibitor bound to the protease domain of hepatitis C virus NS3 protein (NS3p), solved by NMR. The inhibitor exploits interactions with the S' region of NS3p to form a long-lived complex, although the absence of negative charges strongly reduces the association rate. The inhibitor stabilizes the N-terminal domain of NS3p and the substrate-binding site, and correctly aligns catalytic His-Asp residues. These actions were previously attributed exclusively to the cofactor NS4A, which interacts with the N-terminal domain of the NS3p and functions as an activator in vivo. The structure of the inhibitor/NS3p complex is very similar to that of the NS3p-NS4A complex, showing that binding of the NS4A cofactor is not the only event leading to a stable active-site conformation.
authors.affiliation: Department of Chemical Science and Technology, Università di Roma Tor Vergata Via della Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Mariana
authors.initials: M
authors.lastname: Gallo
authors.forename: Matteo
authors.initials: M
authors.lastname: Pennestri
authors.forename: Matthew James
authors.initials: MJ
authors.lastname: Bottomley
authors.forename: Gaetano
authors.initials: G
authors.lastname: Barbato
authors.forename: Tommaso
authors.initials: T
authors.lastname: Eliseo
authors.forename: Maurizio
authors.initials: M
authors.lastname: Paci
authors.forename: Frank
authors.initials: F
authors.lastname: Narjes
authors.forename: Raffaele
authors.initials: R
authors.lastname: De Francesco
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Summa
authors.forename: Uwe
authors.initials: U
authors.lastname: Koch
authors.forename: Renzo
authors.initials: R
authors.lastname: Bazzo
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Cicero
mesh_terms: D000577:Amides / Q000494:pharmacology; D001224:Aspartic Acid / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002384:Catalysis / Q000187:drug effects; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004795:Enzyme Stability / Q000187:drug effects; D006639:Histidine / Q000378:metabolism; D006860:Hydrogen Bonding / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008958:Models, Molecular; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017186:Titrimetry; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D014764:Viral Proteins / Q000378:metabolism*; D014867:Water; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000577:Amides; D001224:Aspartic Acid; D002352:Carrier Proteins; D006639:Histidine; D047908:Intracellular Signaling Peptides and Proteins; D011480:Protease Inhibitors; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; D014867:Water; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C455041:NS4A cofactor peptide, Hepatitis C virus