title: Pyridoxal phosphate inhibits the group I intron splicing.
abstract: The coenzyme pyridoxal phosphate and its analogs were tested for inhibition of the self-splicing of primary transcripts of the phage T4 thymidylate synthase gene (td). Of all compounds examined, the pyridoxal phosphate was the most potent inhibitor and the order of inhibitory efficiency for compounds tested was as follows: pyridoxal phosphate > pyridoxal > pyridoxine > pyridoxamine > pyridoxic acid. Increasing Mg2+ concentration up to 14 mM overcame the suppression of self-splicing by pyridoxal phosphate up to 95% of the level of normal splicing, implying its interference with effective catalysis of Mg2+. The kinetic analysis demonstrated that pyridoxal phosphate acts as a mixed type noncompetitive inhibitor for the td intron RNA with a K(i) of 11.8 mM. The specificity of the splicing inhibition by pyridoxal phosphate is predominantly due to increases in K(m) and decreases in V(max) values.
authors.affiliation: Department of Biology, Dongguk University, Seoul, Korea.
authors.forename: Chul
authors.initials: C
authors.lastname: Jung
authors.forename: Sook
authors.initials: S
authors.lastname: Shin
authors.forename: In Kook
authors.initials: IK
authors.lastname: Park
mesh_terms: D017122:Bacteriophage T4 / Q000201:enzymology; D007438:Introns / Q000235:genetics*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000737:chemistry / Q000494:pharmacology*; D012326:RNA Splicing / Q000187:drug effects*; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors / Q000235:genetics
chemical_list: D011732:Pyridoxal Phosphate; D013940:Thymidylate Synthase; D008274:Magnesium