Molecular analysis of the Cryptococcus neoformans ADE2 gene, a selectable marker for transformation and gene disruption

Fungal Genet Biol. 1999 Jun;27(1):36-48. doi: 10.1006/fgbi.1999.1126.


Cryptococcus neoformans is an important fungal pathogen of man. The incidence of cryptococcal disease has increased dramatically in patients immunocompromised because of HIV infection, organ transplantation, or treatment with cytotoxic chemotherapy or corticosteroids. This organism is an excellent model for molecular dissection of fungal pathogenesis and virulence factors. Here we report the nucleotide sequence of the C. neoformans serotype D genomic ADE2 gene, which encodes a phosphoribosylaminoimidazole carboxylase required for purine biosynthesis. Importantly, this version of the ADE2 gene has been used as the selectable marker for virtually all gene disruptions by transformation and homologous recombination in C. neoformans. We compare the nucleotide and amino acid sequences of the ADE2 gene and product to other highly related adenine biosynthetic genes and enzymes from other yeasts and fungi. We also describe a series of convenient ADE2 cassettes for gene disruption construct preparation. Finally, we have identified the ade2 mutations in strains M001 and M049, adenine auxotrophic mutants derived from the serotype A strain H99. These mutant strains have served as recipients for targeted gene disruptions using the ADE2 gene. These studies should facilitate transformation and gene disruption approaches using the ADE2 selectable marker in this important human fungal pathogen.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Biomarkers
  • Carboxy-Lyases / genetics*
  • Cryptococcus neoformans / chemistry
  • Cryptococcus neoformans / classification
  • Cryptococcus neoformans / genetics*
  • DNA, Fungal / chemistry
  • DNA, Fungal / genetics
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation
  • Plasmids / genetics
  • Recombinant Fusion Proteins / genetics
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Serotyping
  • Transformation, Genetic


  • Biomarkers
  • DNA, Fungal
  • Recombinant Fusion Proteins
  • Carboxy-Lyases
  • phosphoribosylaminoimidazole carboxylase

Associated data

  • GENBANK/AF112302