Halogenated benzimidazoles and benzotriazoles as inhibitors of the NTPase/helicase activities of hepatitis C and related viruses.
A search has been initiated for lead inhibitors of the nonstructural protein 3 (NS3)-associated NTPase/helicase activities of hepatitis C virus, the related West Nile virus, Japanese encephalitis virus and the human mitochondrial Suv3 enzyme. Random screening of a broad range of unrelated low-molecular mass compounds, employing both RNA and DNA substrates, revealed that 4,5,6,7-tetrabromobenzotriazole (TBBT) hitherto known as a potent highly selective inhibitor of protein kinase 2, is a good inhibitor of the helicase, but not NTPase, activity of hepatitis C virus NTPase/helicase. The IC50 is approximately 20 micro m with a DNA substrate, but only 60 micro m with an RNA substrate. Several related analogues of TBBT were enzyme- and/or substrate-specific inhibitors. For example, 5,6-dichloro-1-(beta-d-ribofuranosyl)benzotriazole (DRBT) was a good, and selective, inhibitor of the West Nile virus enzyme with an RNA substrate (IC50 approximately 0.3 micro m), but much weaker with a DNA substrate (IC50 approximately 3 micro m). Preincubation of the enzymes, but not substrates, with DRBT enhanced inhibitory potency, e.g. the IC50 vs the hepatitis C virus helicase activity was reduced from 1.5 to 0.1 micro m. No effect of preincubation was noted with TBBT, suggesting a different mode of interaction with the enzyme. The tetrachloro congener of TBBT, 4,5,6,7,-tetrachlorobenzotriazole (TCBT; a much weaker inhibitor of casein kinase 2) is also a much weaker inhibitor than TBBT of all four helicases. Kinetic studies, supplemented by comparison of ATP-binding sites, indicated that, unlike the case with casein kinase 2, the mode of action of the inhibitors vs the helicases is not by interaction with the catalytic ATP-binding site, but rather by occupation of an allosteric nucleoside/nucleotide binding site. The halogeno benzimidazoles and benzotriazoles included in this study are excellent lead compounds for the development of more potent inhibitors of hepatitis C virus and other viral NTPase/helicases.
Borowski
Peter
P
Abteilung fur Virologie, Bernhard-Nocht-Institut fur Tropenmedizin, Hamburg, Germany. borowski@bni.uni-hamburg.de
Deinert
Johanna
J
Schalinski
Sarah
S
Bretner
Maria
M
Ginalski
Krzysztof
K
Kulikowski
Tadeusz
T
Shugar
David
D
D017766:Acid Anhydride Hydrolases / Q000037:antagonists & inhibitors*; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000737:chemistry; D000998:Antiviral Agents / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology*; D001665:Binding Sites; D004265:DNA Helicases / Q000037:antagonists & inhibitors*; D016174:Hepacivirus / Q000187:drug effects / Q000201:enzymology*; D007700:Kinetics; D008958:Models, Molecular; D043583:Nucleoside-Triphosphatase; D011487:Protein Conformation; D013379:Substrate Specificity; D014230:Triazoles / Q000494:pharmacology*; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D012697:Serine Endopeptidases; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D017766:Acid Anhydride Hydrolases; D000251:Adenosine Triphosphatases; D000998:Antiviral Agents; D001562:Benzimidazoles; D004265:DNA Helicases; D043583:Nucleoside-Triphosphatase; D014230:Triazoles; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C012771:benzotriazole