title: Potent hepatitis C inhibitors bind directly to NS5A and reduce its affinity for RNA.
abstract: Hepatitis C virus (HCV) infection affects more than 170 million people. The high genetic variability of HCV and the rapid development of drug-resistant strains are driving the urgent search for new direct-acting antiviral agents. A new class of agents has recently been developed that are believed to target the HCV protein NS5A although precisely where they interact and how they affect function is unknown. Here we describe an in vitro assay based on microscale thermophoresis and demonstrate that two clinically relevant inhibitors bind tightly to NS5A domain 1 and inhibit RNA binding. Conversely, RNA binding inhibits compound binding. The compounds bind more weakly to known resistance mutants L31V and Y93H. The compounds do not affect NS5A dimerisation. We propose that current NS5A inhibitors act by favouring a dimeric structure of NS5A that does not bind RNA.
authors.affiliation: ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia.
authors.forename: David B
authors.initials: DB
authors.lastname: Ascher
authors.affiliation: 1] ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia [2] Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia.
authors.forename: Jerome
authors.initials: J
authors.lastname: Wielens
authors.affiliation: ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia.
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Nero
authors.affiliation: ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia.
authors.forename: Larissa
authors.initials: L
authors.lastname: Doughty
authors.affiliation: ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Morton
authors.affiliation: 1] ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia [2] Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Parker
mesh_terms: D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D024882:Drug Resistance, Viral / Q000235:genetics; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D008968:Molecular Conformation; D062105:Molecular Docking Simulation; D009154:Mutation; D011485:Protein Binding / Q000187:drug effects; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization / Q000187:drug effects; D012367:RNA, Viral / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase
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