Psammaplin A inhibits hepatitis C virus NS3 helicase.
Hepatitis C virus (HCV) is the causative agent of hepatitis C, a chronic infectious disease that can lead to development of hepatocellular carcinoma. The NS3 nucleoside triphosphatase (NTPase)/helicase has an essential role in HCV replication, and is therefore an attractive target for direct-acting antiviral strategies. In this study, we employed high-throughput screening using a photo-induced electron transfer (PET) system to identify an inhibitor of NS3 helicase from marine organism extracts. We successfully identified psammaplin A as a novel NS3 inhibitor. The dose-response relationship clearly demonstrates the inhibition of NS3 RNA helicase and ATPase activities by psammaplin A, with IC₅₀ values of 17 and 32 μM, respectively. Psammaplin A has no influence on the apparent Km value (0.4 mM) of NS3 ATPase activity, and acts as a non-competitive inhibitor. Additionally, it inhibits the binding of NS3 to single-stranded RNA in a dose-dependent manner. Furthermore, psammaplin A shows an inhibitory effect on viral replication, with EC₅₀ values of 6.1 and 6.3 μM in subgenomic replicon cells derived from genotypes 1b and 2a, respectively. We postulate that psammaplin A is a potential anti-viral agent through the inhibition of ATPase, RNA binding and helicase activities of NS3.
Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
Kazi Abdus
KA
Salam
Atsushi
A
Furuta
Naohiro
N
Noda
Satoshi
S
Tsuneda
Yuji
Y
Sekiguchi
Atsuya
A
Yamashita
Kohji
K
Moriishi
Masamichi
M
Nakakoshi
Masayoshi
M
Tsubuki
Hidenori
H
Tani
Junichi
J
Tanaka
Nobuyoshi
N
Akimitsu
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D004220:Disulfides / Q000737:chemistry / Q000494:pharmacology*; D016174:Hepacivirus / Q000187:drug effects* / Q000502:physiology; D012313:RNA / Q000378:metabolism; D020365:RNA Helicases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D000251:Adenosine Triphosphatases; D000998:Antiviral Agents; D004220:Disulfides; D012313:RNA; D020365:RNA Helicases; D014443:Tyrosine; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C098378:psammaplin A