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

• A cluster of genes essential for degradation of proline to glutamate (put) is located between the pyrC and pyrD loci at min 22 of the Salmonella chromosome [8].
• Isolation and characterization of pyrimidine mutants of Salmonella typhimurium altered in expression of pyrC, pyrD, and pyrE [9].
• Expression of the Salmonella typhimurium pyrD gene was found to be repressed two-fold when cells were grown in the presence of hypoxanthine [10].

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

• This requirement for arginine was completely suppressed by pyrB mutations and partially suppressed by pyrC and pyrD mutations [11].
• Regulation by pyrimidines was unaffected by either of the two PUR box mutations, showing that purine and pyrimidine control of pyrD expression can operate independently [10].
• Dihydroorotate dehydrogenase, orotate phosphoribosyltransferase and orotidine-5'-monophosphate (OMP) decarboxylase showed peaks of activity corresponding to the mid-point of the exponential phase of growth while remaining comparatively stable in the stationary phase [12].
• Derepression studies carried out by starving individual pyrimidine (Pyr-) deletion mutants for uracil showed that the extent of derepression obtained for aspartate carbamoyltransferase, dihydroorotase and dihydroorotate dehydrogenase depended on the location of the pyr gene mutation [12].

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].

References