A positive selection for mutants lacking orotidine-5'-phosphate decarboxylase activity in yeast: 5-fluoro-orotic acid resistance

Mol Gen Genet. 1984;197(2):345-6. doi: 10.1007/BF00330984.


Mutations at the URA3 locus of Saccharomyces cerevisiae can be obtained by a positive selection. Wild-type strains of yeast (or ura3 mutant strains containing a plasmid-borne URA3+ gene) are unable to grow on medium containing the pyrimidine analog 5-fluoro-orotic acid, whereas ura3- mutants grow normally. This selection, based on the loss of orotidine-5'-phosphate decarboxylase activity seems applicable to a variety of eucaryotic and procaryotic cells.

MeSH terms

  • Carboxy-Lyases / genetics*
  • Drug Resistance, Microbial
  • Fungal Proteins / genetics*
  • Microbiological Techniques
  • Orotic Acid / analogs & derivatives*
  • Orotic Acid / pharmacology
  • Orotidine-5'-Phosphate Decarboxylase / genetics*
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics*


  • Fungal Proteins
  • Orotic Acid
  • 5-fluoroorotic acid
  • Carboxy-Lyases
  • Orotidine-5'-Phosphate Decarboxylase