title: De novo synthesis of pyrimidine nucleotides by Helicobacter pylori.
abstract: The incorporation of pyrimidine nucleotide precursors into Helicobacter pylori and the activities of enzymes involved in their synthetic pathways were investigated by radioactive tracer analysis and 31P nuclear magnetic resonance spectroscopy. The bacterium was found to take up aspartate and bicarbonate and to incorporate carbon atoms from these precursors into its genomic DNA. Orotate, an intermediate of de novo pyrimidine biosynthesis, and uracil and uridine, precursors for pyrimidine pathways, were also incorporated by the micro-organism. Radiolabelled substrates were used to assess the activities of aspartate transcarbamoylase, orotate phosphoribosyltransferase, orotidylate decarboxylase, CTP synthetase, uracil phosphoribosyltransferase, thymidine kinase and deoxycytidine kinase in bacterial lysates. The study provided evidence for the presence in H. pylori of an operational de novo pathway, and a less active salvage pathway for the biosynthesis of pyrimidine nucleotides.
authors.affiliation: School of Biochemistry and Molecular Genetics, University of New South Wales, Kensington, Australia.
authors.forename: G L
authors.initials: GL
authors.lastname: Mendz
authors.forename: B M
authors.initials: BM
authors.lastname: Jimenez
authors.forename: S L
authors.initials: SL
authors.lastname: Hazell
authors.forename: A M
authors.initials: AM
authors.lastname: Gero
authors.forename: W J
authors.initials: WJ
authors.lastname: O'Sullivan
mesh_terms: D001221:Aspartate Carbamoyltransferase / Q000032:analysis; D001224:Aspartic Acid / Q000378:metabolism; D001639:Bicarbonates / Q000378:metabolism; D019731:Carbon-Nitrogen Ligases; D003842:Deoxycytidine Kinase / Q000032:analysis; D016480:Helicobacter pylori / Q000201:enzymology / Q000378:metabolism*; D007553:Isotope Labeling; D008025:Ligases / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D009962:Orotate Phosphoribosyltransferase / Q000032:analysis; D010430:Pentosyltransferases / Q000032:analysis; D010759:Phosphorus Isotopes; D011742:Pyrimidine Nucleotides / Q000096:biosynthesis*
chemical_list: D001639:Bicarbonates; D010759:Phosphorus Isotopes; D011742:Pyrimidine Nucleotides; D001224:Aspartic Acid; D001221:Aspartate Carbamoyltransferase; D010430:Pentosyltransferases; D009962:Orotate Phosphoribosyltransferase; C023269:uracil phosphoribosyltransferase; D003842:Deoxycytidine Kinase; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C019951:CTP synthetase