title: Vitamin B12 stalls the 80 S ribosomal complex on the hepatitis C internal ribosome entry site.
abstract: The effect of cyanocobalamin (CNCbl, vitamin B12) on hepatitis C virus internal ribosome entry site (HCV IRES)-dependent initiation of translation was studied by ribosomal toeprinting and sucrose gradient centrifugation analysis. These results suggested that CNCbl did not inhibit HCV IRES-dependent translation by a competitive binding mechanism. CNCbl allowed 80 S elongation complex formation on the mRNA, but stalled the initiation at that point, effectively trapping the 80 S ribosomal complexes on the HCV IRES. CNCbl had no effect on cap-dependent mRNA, consistent with the known mRNA specificity of this translational inhibitor. To help elucidate the mechanism, comparative data were collected for the well-characterised translation inhibitors cycloheximide and 5'-guanylyl-imidophosphate. Although CNCbl stalled HCV IRES-dependent translation at approximately the same step in initiation as cycloheximide, the mechanisms of these two inhibitors are distinct.
authors.affiliation: Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Herston, Qld 4029, Australia.
authors.forename: Seyedtaghi S
authors.initials: SS
authors.lastname: Takyar
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Gowans
authors.forename: William B
authors.initials: WB
authors.lastname: Lott
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D003513:Cycloheximide / Q000494:pharmacology; D016174:Hepacivirus / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis / Q000187:drug effects*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism*; D014805:Vitamin B 12 / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D003513:Cycloheximide; D014805:Vitamin B 12