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Gene Review

pyrD  -  dihydroorotate dehydrogenase 2

Salmonella enterica subsp. enterica serovar Typhimurium str. LT2

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Disease relevance of pyrD

  • Conformational heterogeneity in the Salmonella typhimurium pyrC and pyrD leader mRNAs produced in vivo [1].
  • In total, a sequence of 1286 nucleotide pairs was determined wherein a single open-reading-frame of 1011 bp, encoding a polypeptide of 336 amino acids having 95% similarity with the Escherichia coli pyrD gene product, was identified [2].

High impact information on pyrD

  • In accordance with predictions based on the nucleotide sequence, the results showed that the 5' end of pyrC and pyrD leader mRNA isolated from repressed cultures is folded into a secondary structure, whereas it is largely unstructured in mRNA isolated from derepressed cultures [3].
  • It should accumulate to high levels in pyrC or pyrD mutants when expression of the pyrA and pyrB genes is elevated [4].
  • The mutation resulted in an alteration in the regulation of synthesis of enzymes involved in de novo pyrimidine biosynthesis but did not establish a functional block in dihydroorotate dehydrogenase activity in vivo [5].
  • Mutations in pepN (leading to loss of peptidase N [1974] are co-transducible with pyrD [6].
  • (ii) The expression of pyrC and pyrD is regulated predominantly by a cytidine nucleotide [7].

Chemical compound and disease context of pyrD


Biological context of pyrD

  • Growth of Salmonella typhimurium pyrC or pyrD auxotrophs was severely inhibited in media that caused derepressed pyr gene expression [4].
  • Gel retardation experiments provided evidence that PurR binds to a PUR box centered 27 base pairs upstream of the -35 region of the pyrD promoter [10].
  • In a strain harbouring a purR6::Tn10 mutation inactivating the purine regulon repressor (PurR), expression of pyrD was not repressed by hypoxanthine [10].
  • Parental strains of Salmonella typhimurium having a specific pyr gene (pyrC, pyrD, or pyrE) fused to the structural genes of the lac operon through the specialized transducing phage Mu dl (ApRlac) were used to construct thermostable derivatives for purposes of conducting a genetic and biochemical characterization of the individual pyr genes [9].

Associations of pyrD with chemical compounds


Other interactions of pyrD

  • The conformation of the leader regions of wild type pyrC and pyrD mRNA has been investigated by chemical and enzymatic probing of RNA isolated from cultures grown in repressing and derepressing conditions [3].
  • The direction of transcription of each pyr gene in relation to the current linkage map was defined with both pyrC and pyrE being transcribed counterclockwise and pyrD exhibiting clockwise transcription [9].


  1. Conformational heterogeneity in the Salmonella typhimurium pyrC and pyrD leader mRNAs produced in vivo. Sørensen, K.I. Nucleic Acids Res. (1994) [Pubmed]
  2. Cloning, nucleotide sequence and regulation of the Salmonella typhimurium pyrD gene encoding dihydroorotate dehydrogenase. Frick, M.M., Neuhard, J., Kelln, R.A. Eur. J. Biochem. (1990) [Pubmed]
  3. Conformational heterogeneity in the Salmonella typhimurium pyrC and pyrD leader mRNAs produced in vivo. Sørensen, K.I. Nucleic Acids Res. (1994) [Pubmed]
  4. Toxicity of the pyrimidine biosynthetic pathway intermediate carbamyl aspartate in Salmonella typhimurium. Turnbough, C.L., Bochner, B.R. J. Bacteriol. (1985) [Pubmed]
  5. A Salmonella typhimurium mutant dependent upon carbamyl aspartate for resistance to 5-fluorouracil is specifically affected in ubiquinone biosynthesis. Zak, V.L., Kelln, R.A. J. Bacteriol. (1981) [Pubmed]
  6. Gentic mapping of Salmonella typhimurium peptidase mutations. Miller, C.G. J. Bacteriol. (1975) [Pubmed]
  7. Control of expression of the pyr genes in Salmonella typhimurium: effects of variations in uridine and cytidine nucleotide pools. Schwartz, M., Neuhard, J. J. Bacteriol. (1975) [Pubmed]
  8. Cluster of genes controlling proline degradation in Salmonella typhimurium. Ratzkin, B., Roth, J. J. Bacteriol. (1978) [Pubmed]
  9. Isolation and characterization of pyrimidine mutants of Salmonella typhimurium altered in expression of pyrC, pyrD, and pyrE. Kelln, R.A., Neuhard, J., Stauning, L. Can. J. Microbiol. (1985) [Pubmed]
  10. Dual control by purines and pyrimidines of the expression of the pyrD gene of Salmonella typhimurium. Vial, T.C., Baker, K.E., Kelln, R.A. FEMS Microbiol. Lett. (1993) [Pubmed]
  11. pryB mutations as suppressors of arginine auxotrophy in Salmonella typhimurium. Jenness, D.D., Schachman, H.K. J. Bacteriol. (1980) [Pubmed]
  12. Repression and derepression of the enzymes of the pyrimidine biosynthetic pathway in Salmonella typhimurium. Smith, J.M., Kelln, R.A., O'Donovan, G.A. J. Gen. Microbiol. (1980) [Pubmed]
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