title: Viral NS3 helicase activity is inhibited by peptides reproducing the Arg-rich conserved motif of the enzyme (motif VI).
abstract: The NTPase/helicase of Flaviviridae viruses is one of the essential components of their replication complex. The enzyme is defined by the presence of seven highly conserved amino acid motifs. Random screening of numerous hepatitis C virus (HCV) derived peptides, revealed a basic amino acid stretch corresponding to motif VI of the HCV NTPase/helicase (amino acids 1487-1500 of the HCV polyprotein). This peptide inhibited the unwinding activity of the enzyme with an IC(50)=0.2 microM. Peptides corresponding to motif VI of HCV, West Nile virus (WNV) and Japanese encephalitis virus (JEV) were synthesized and tested as inhibitors of NTPase and unwinding reactions mediated by the viral enzymes. Peptides distinguished in regard to their length and structure. Between the peptides tested HCV(1487-1500) reproducing the sequence of motif VI was the most potent inhibitor of helicase activities of investigated enzymes. Other respective peptides were rather modest inhibitors. The examined peptides inhibited the Flaviviridae helicases in the following order of potency: HCV(1487-1500)>WNV(1959-1572)>JEV(1962-1975). Interestingly, the susceptibility of the helicase activity to the inhibition by the peptides was similar and in the row: HCV>WNV>JEV. The inhibition results from binding and blockade of the active site of the enzyme lyes beyond the NTP-binding and hydrolyzing site. The kinetic analyses indicated that the binding of the peptides do not interfere with the NTPase activity of the enzymes. The peptide may serve as effective and selective tool to reduce the virus propagation.
authors.affiliation: Department of Molecular Biology, Institute of Environmental Protection, John Paul II Catholic University of Lublin, Al. Krasnicka 102, 20-718 Lublin, Poland.
authors.forename: Peter
authors.initials: P
authors.lastname: Borowski
authors.forename: Maite V
authors.initials: MV
authors.lastname: Heising
authors.forename: Isabel Barreto
authors.initials: IB
authors.lastname: Miranda
authors.forename: Ching-Len
authors.initials: CL
authors.lastname: Liao
authors.forename: Joonho
authors.initials: J
authors.lastname: Choe
authors.forename: Andrea
authors.initials: A
authors.lastname: Baier
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry*; D001483:Base Sequence; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018067:Flaviviridae / Q000201:enzymology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology*; D020365:RNA Helicases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification; D012697:Serine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification; D013379:Substrate Specificity; D014709:Vero Cells; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000302:isolation & purification; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D001120:Arginine; D004791:Enzyme Inhibitors; D010455:Peptides; D020365:RNA Helicases; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases