title: Identification and characterization of an operon in Salmonella typhimurium involved in thiamine biosynthesis.
abstract: Thiamine pyrophosphate (TPP) is synthesized de novo in Salmonella typhimurium and is a required cofactor for many enzymes in the cell. Five kinase activities have been implicated in TPP synthesis, which involves joining a 4-methyl-5-(beta-hydroxyethyl)thiazole (THZ) moiety and a 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) moiety. We report here identification of a 2-gene operon involved in thiamine biosynthesis and present evidence that the genes in this operon, thiMD, encode two previously identified kinases, THZ kinase and HMP phosphate (HMP-P) kinase, respectively. We further show that this operon belongs to the growing class of genes involved in TPP synthesis that are transcriptionally regulated by TPP. Our data are consistent with ThiM being a salvage enzyme and ThiD being a biosynthetic enzyme involved in TPP synthesis, as previously suggested.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, 53706, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Petersen
authors.forename: D M
authors.initials: DM
authors.lastname: Downs
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D004269:DNA, Bacterial; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016296:Mutagenesis; D009154:Mutation; D009876:Operon; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011743:Pyrimidines / Q000378:metabolism; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013831:Thiamine / Q000096:biosynthesis*; D013835:Thiamine Pyrophosphate
chemical_list: C101901:4-amino-5-hydroxymethyl-2-methylpyrimidine; D004269:DNA, Bacterial; D011743:Pyrimidines; C108435:4-methyl-5-(beta-hydroxyethyl)thiazole kinase; D017853:Phosphotransferases (Alcohol Group Acceptor); C108436:4-amino-5-(hydroxymethyl)-2-methylpyrimidine phosphate kinase; D017856:Phosphotransferases (Phosphate Group Acceptor); D013835:Thiamine Pyrophosphate; D013831:Thiamine