Analysis of a Candida albicans gene that encodes a novel mechanism for resistance to benomyl and methotrexate

Mary E. Fling*, Jan Kopf, Aviva Tamarkin, Jessica A. Gorman, Herbert A. Smith, Yigal Koltin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The pathogenic yeast, Candida albicans, is insensitive to the anti-mitotic drug, benomyl, and to the dihydrofolate reductase inhibitor, methotrexate. Genes responsible for the intrinsic drug resistance were sought by transforming Saccharomyces cerevisiae, a yeast sensitive to both drugs, with genomic C. albicans libraries and screening on benomyl or methotrexate. Restriction analysis of plasmids isolated from benomyl- and methotrexate-resistant colonies indicated that both phenotypes were encoded by the same DNA fragment. Sequence analysis showed that the fragments were nearly identical and contained a long open reading frame of 1694 bp (ORF1) and a small ORF of 446 bp (ORF2) within ORF1 on the opposite strand. By site-directed mutagenesis, it was shown that ORF1 encoded both phenotypes. The protein had no sequence similarity to any known proteins, including β-tubulin, dihydrofolate reductase, and the P-glycoprotein of the multi-drug resistance family. The resistance gene was detected in several C. albicans strains and in C. stellatoidea by DNA hybridization and by the polymerase chain reaction.

Original languageEnglish
Pages (from-to)318-329
Number of pages12
JournalMolecular Genetics and Genomics
Issue number2
StatePublished - Jun 1991


  • Benomyl
  • Candida albicans
  • DNA sequence
  • Drug resistance
  • Methotrexate


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