title: Nucleotide sequence analysis of genes purH and purD involved in the de novo purine nucleotide biosynthesis of Escherichia coli.
abstract: 5'-Phosphoribosylglycinamide synthetase (EC 6.3.4.13) and 5'-phosphoribosyl 5-aminoimidazole-4-carboxamide transformylase (EC 2.1.2.3) are enzymes involved in the de novo purine nucleotide synthesis and are encoded by purD and purH genes of Escherichia coli, respectively. A 3535-nucleotide sequence containing the purHD locus and the upstream region of the rrnE gene was determined. This sequence specifies two open reading frames, ORF-1 and ORF-2, encoding proteins with the expected Mr of 57,329 and 46,140, respectively. The plasmids carrying ORF-1 complemented not only the mutant cells defective in purH of E. coli but also the cells of Salmonella typhimurium lacking the activity of IMP cyclohydrolase (EC 3.5.4.10) which catalyzes the conversion of 5'-phosphoribosyl 5-formylaminoimidazole-4-carboxamide to IMP. The E. coli purH gene, therefore, specifies bifunctional 5'-phosphoribosyl 5-aminoimidazole-4-carboxamide transformylase-IMP cyclohydrolase. The plasmids carrying ORF-2 were able to complement the mutant cells defective in purD. Both purH and purD genes constitute a single operon and are coregulated in expression by purines as other purine genes are. A highly conserved 16-nucleotide sequence termed the PUR box (Watanabe, W., Sampei, G., Aiba, A., and Mizobuchi, K. (1989) J. Bacteriol. 171, 198-204; Tiedeman, A.A., Keyhani, J., Kamholz, J., Daum, H. A., III, Gots, J.S., and Smith, J.M. (1989) J. Bacteriol. 171, 205-212) was found in the control region of the purHD operon and compared with the sequences of the control regions of other purine operons.
authors.affiliation: Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Aiba
authors.forename: K
authors.initials: K
authors.lastname: Mizobuchi
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D019731:Carbon-Nitrogen Ligases; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D019877:Hydroxymethyl and Formyl Transferases; D008025:Ligases / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009876:Operon; D051027:Phosphoribosylaminoimidazolecarboxamide Formyltransferase; D010957:Plasmids; D011685:Purine Nucleotides / Q000096:biosynthesis*; D015183:Restriction Mapping; D012486:Salmonella typhimurium / Q000201:enzymology / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D011685:Purine Nucleotides; D019877:Hydroxymethyl and Formyl Transferases; D051027:Phosphoribosylaminoimidazolecarboxamide Formyltransferase; D000217:Acyltransferases; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C022387:phosphoribosylamine-glycine ligase