title: NAD+ inhibits the self-splicing of the group I intron.
abstract: We investigated the effects of the coenzyme NAD+ (nicotinamide adenine dinucleotide) and its analogs on the self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td). Of all the nicotinamide coenzymes and analogs tested, NADP+ was the strongest inhibitor, with a potency approximately threefold that of NAD+. Kinetic analysis demonstrated that NAD+ acts as a mixed type noncompetitive inhibitor for the td intron RNA with a K(i) of 4.1 mM. The splicing specificity inhibition by NAD+ is predominantly due to changes in Km and kcat, and was Mg2+ concentration dependent. The results suggest that both the ADP and nicotinamide moieties are the key structural features in NAD+ responsible for the inhibition of splicing.
authors.affiliation: Department of Biology, Dongguk University, Seoul, 100-715, Korea.
authors.forename: I K
authors.initials: IK
authors.lastname: Park
authors.forename: J Y
authors.initials: JY
authors.lastname: Kim
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D017122:Bacteriophage T4 / Q000235:genetics; D001665:Binding Sites; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D007438:Introns; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride / Q000494:pharmacology; D008956:Models, Chemical; D009243:NAD / Q000235:genetics* / Q000494:pharmacology / Q000502:physiology*; D009249:NADP / Q000378:metabolism; D009536:Niacinamide / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013940:Thymidylate Synthase / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D011994:Recombinant Proteins; D015636:Magnesium Chloride; D009243:NAD; D009536:Niacinamide; D009249:NADP; D000244:Adenosine Diphosphate; D012313:RNA; D006160:Guanosine Triphosphate; D013940:Thymidylate Synthase; D008274:Magnesium