The hepatitis C virus (HCV) nonstructural (NS)3-NS4A serine protease heterocomplex is a prime target for development of novel HCV therapies, due to its essential role in maturation of the viral polyprotein. While the mode of substrate/inhibitor recognition of the HCV NS3/NS4A serine protease has been extensively studied in vitro, important molecular aspects of the mechanism of action for this m...

Human APOBEC3G (hA3G) is a cytidine deaminase that restricts replication of certain viruses. We have previously reported that hA3G was a host restriction factor against hepatitis C virus (HCV) replication, and hA3G stabilizers showed a significant inhibitory activity against HCV. However, the molecular mechanism of hA3G against HCV remains unknown. We show in this study that hA3G's C-terminal d...

UNLABELLED Pestiviruses form a genus in the Flaviviridae family of small enveloped viruses with a positive-sense single-stranded RNA genome. Viral replication in this family requires the activity of a superfamily 2 RNA helicase contained in the C-terminal domain of nonstructural protein 3 (NS3). NS3 features two conserved RecA-like domains (D1 and D2) with ATPase activity, plus a third domain (...

The molecular basis of the low-pH activation of the helicase encoded by the hepatitis C virus (HCV) was examined using either a full-length NS3 protein/NS4A cofactor complex or truncated NS3 proteins lacking the protease domain, which were isolated from three different viral genotypes. All proteins unwound RNA and DNA best at pH 6.5, which demonstrate that conserved NS3 helicase domain amino ac...

Typical assays used to discover and analyze small molecules that inhibit the hepatitis C virus (HCV) NS3 helicase yield few hits and are often confounded by compound interference. Oligonucleotide binding assays are examined here as an alternative. After comparing fluorescence polarization (FP), homogeneous time-resolved fluorescence (HTRF®; Cisbio) and AlphaScreen® (Perkin Elmer) assays, an FP-...

Japanese encephalitis virus (JEV) is a flavivirus that threatens more than half of the world's population. Vaccination can prevent the disease, but no specific antiviral drug is yet available for clinical therapy, and the death rate caused by JEV can reach as high as 60%. The C-terminus of non-structural protein 3 (NS3) of flavivirus encodes helicase and has been identified as a potential drug ...

The NS3 protein of hepatitis C virus contains a bipartite structure consisting of an N-terminal serine protease and a C-terminal DEAD box helicase. We show that the C-terminal domain has ATPase and panhelicase activities. The integrity of the helicase function is dependent on the conserved DEAD motif and can be abolished by a His-Ala point mutation, leaving a fully functional nucleoside triphos...

This study examines the effects of 1-N,4-N-bis[4-(1H-benzimidazol-2-yl)phenyl]benzene-1,4-dicarboxamide ((BIP)(2)B) on the NS3 helicase encoded by the hepatitis C virus (HCV). Molecular beacon-based helicase assays were used to show that (BIP)(2)B inhibits the ability of HCV helicase to separate a variety of RNA and DNA duplexes with half-maximal inhibitory concentrations ranging from 0.7 to 5 ...

A series of luminescent Ir(III) complexes were synthesised and evaluated for their ability to act as luminescent G-quadruplex-selective probes. The Ir(III) complex 9, [Ir(phq)2(phen)]PF6 (where phq 1⁄4 2-phenylquinoline; phen 1⁄4 1,10-phenanthroline), exhibited high luminescence in the presence of G-quadruplex DNA compared to dsDNA and ssDNA, and was employed to construct a label-free G-quadrup...

The development of effective therapies for hepatitis C virus (HCV) must take into account genetic variation among HCV strains. Response rates to interferon-based treatments, including the current, preferred treatment of pegylated alpha interferon administered with ribavirin, are genotype specific. Of the numerous HCV inhibitors currently in development as antiviral drugs, nucleotide analogs tha...