title: Inhibition of hepatitis C virus NS3 helicase by manoalide.
abstract: The hepatitis C virus (HCV) causes one of the most prevalent chronic infectious diseases in the world, hepatitis C, which ultimately develops into liver cancer through cirrhosis. The NS3 protein of HCV possesses nucleoside triphosphatase (NTPase) and RNA helicase activities. As both activities are essential for viral replication, NS3 is proposed as an ideal target for antiviral drug development. In this study, we identified manoalide (1) from marine sponge extracts as an RNA helicase inhibitor using a high-throughput screening photoinduced electron transfer (PET) system that we previously developed. Compound 1 inhibits the RNA helicase and ATPase activities of NS3 in a dose-dependent manner, with IC(50) values of 15 and 70 μM, respectively. Biochemical kinetic analysis demonstrated that 1 does not affect the apparent K(m) value (0.31 mM) of NS3 ATPase activity, suggesting that 1 acts as a noncompetitive inhibitor. The binding of NS3 to single-stranded RNA was inhibited by 1. Manoalide (1) also has the ability to inhibit the ATPase activity of human DHX36/RHAU, a putative RNA helicase. Taken together, we conclude that 1 inhibits the ATPase, RNA binding, and helicase activities of NS3 by targeting the helicase core domain conserved in both HCV NS3 and DHX36/RHAU.
authors.affiliation: Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Tokyo 113-0032, Japan.
authors.forename: Kazi Abdus
authors.initials: KA
authors.lastname: Salam
authors.forename: Atsushi
authors.initials: A
authors.lastname: Furuta
authors.forename: Naohiro
authors.initials: N
authors.lastname: Noda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsuneda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sekiguchi
authors.forename: Atsuya
authors.initials: A
authors.lastname: Yamashita
authors.forename: Kohji
authors.initials: K
authors.lastname: Moriishi
authors.forename: Masamichi
authors.initials: M
authors.lastname: Nakakoshi
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Tsubuki
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tani
authors.forename: Junichi
authors.initials: J
authors.lastname: Tanaka
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Akimitsu
mesh_terms: D001483:Base Sequence; D016174:Hepacivirus / Q000378:metabolism*; D006801:Humans; D015394:Molecular Structure; D043583:Nucleoside-Triphosphatase / Q000187:drug effects / Q000378:metabolism; D020365:RNA Helicases / Q000187:drug effects / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology*; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors*; D012697:Serine Endopeptidases; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D043583:Nucleoside-Triphosphatase; D020365:RNA Helicases; D013729:Terpenes; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C045673:manoalide