Disease relevance of URA4

• PYR3 transformants of E. coli pyrC mutants expressed homologous transcripts of a variety of sizes and regained dihydroorotase activity [1].
• The deduced amino acid sequence of dihydroorotase was examined and compared with homologous amino acid sequences of Salmonella typhimurium, Escherichia coli and Drosophila melanogaster [2].

High impact information on URA4

• The uninducible phenotype of this mutant is completely suppressed by an ochre suppressor, strengthening the hypothesis that PPR2 acts on URA4 transcription through the synthesis of a regulatory protein [3].
• Dihydroorotase, the third enzymatic activity of the pyrimidine pathway, is encoded in Saccharomyces cerevisiae by a single gene URA4, which is induced at the transcriptional level by accumulation of ureidosuccinic acid [3].
• They had also regained dihydroorotase activity, although its level did not correlate with the PYR3 gene copy number [1].
• We also have genetically mapped the STE11 gene to chromosome XII, 40 centimorgans from ura4 [4].
• The mammalian enzyme is part of a 240-kDa multifunctional protein which also has the second (aspartate carbamoyltransferase, EC 2.1.3.2), and third (dihydroorotase, EC 3.5.2.3) activities of the pathway [5].

Biological context of URA4

• The cloned URA4 gene was shown to be located on the 790-kbp Chromosome (chr) VIII of S. exiguus Yp74L-3 [6].
• This fact indicates that the S. exiguus URA4 gene encodes orotidine-5'-phosphate decarboxylase (OMP decarboxylase) and demonstrates that vector plasmids for S. cerevisiae are also usable in S. exiguus [7].
• There are also two sites of interest that match known concensus phosphorylation sites; one is located in the distal part of the CPSase domain, the other in the connector region between DHOase-like and ATCase domains [8].
• In addition, significant sequence similarity was found with the protein encoded by the yeast gene PPR2, which is involved in regulation of URA4 gene expression [9].
• A potential active site has been predicted for dihydroorotase from these comparisons [2].

Associations of URA4 with chemical compounds

• Mutations in the URA3 and URA4 genes were specifically selected with 5-fluoroorotic acid (5-FOA) [7].
• Starting from the amino terminus of the protein, these are glutamine amido transferase, CPSase, a domain that resembles dihydroorotase (DHOase-like) but does not have DHOase activity, and ATCase [8].
• As in Saccharomyces cerevisiae, aspartate transcarbamoylase is assembled on a multifunctional protein including a dihydroorotase-like cryptic domain in Schizosaccharomyces pombe [10].
• This unusual type of Ty-mediated gene activation is possible as the URA2 gene product is a multifunctional protein containing the carbamoyl phosphate synthetase (CPSase), the ATCase and a cryptic dihydroorotase (DHOase) domain [11].
• The 5' end maps to the distal end of the locus (relative to the centromere) and transcription proceeds through the domains encoding dihydroorotase, carbamyl phosphate synthetase and finally aspartate transcarbamylase [12].

Other interactions of URA4

• Vector plasmids containing the URA3 gene and an autonomously replicating sequence (ARS) of S. cerevisiae produced sufficient amounts of Ura+ transformants from the ura4 mutant of S. exiguus [7].
• Linkage to ura4 by about 44 centiMorgans places leu3 on the right arm of this chromosome [13].
• Organization of the yeast URA2 gene: identification of a defective dihydroorotase-like domain in the multifunctional carbamoylphosphate synthetase-aspartate transcarbamylase complex [14].

Analytical, diagnostic and therapeutic context of URA4

• After characterisation by restriction mapping and Southern hybridisation, the cloned gene was used as a probe to measure URA4 transcription and to examine its regulation [15].
• Finally, we propose the use of the URA4 gene as a convenient selective marker for genetic engineering in S. pombe [15].

References