Chemosensitisation of drug-resistant and drug-sensitive yeast cells to antifungals

Jana Cernicka, Zuzana Kozovska, Martina Hnatova, Martin Valachovic, Ivan Hapala, Zsuzsanna Riedl, György Hajós, Julius Subik

Research output: Contribution to journalArticle

21 Citations (Scopus)


Multidrug resistance in yeast results from overexpression of genes encoding drug efflux transporters owing to gain-of-function mutations in transcription factors regulating their expression. We have screened a library of synthetic compounds for modulators of drug resistance using the multidrug-resistant Saccharomyces cerevisiae pdr3-9 mutant strain. One of the compounds, 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT), displayed weak antifungal activity and strongly inhibited the growth of yeast cells in combination with subinhibitory concentrations of other antifungals with a different mode of action. Biological activity of CTBT was demonstrated in Saccharomyces, Kluyveromyces and Candida yeast species grown on solid and in liquid media. The chemosensitising effect of CTBT, manifested as increased antifungal activity of fluconazole, was demonstrated in yeast mutant strains with deleted genes encoding the major multidrug resistance transcription factors Yap1p, Pdr1p and Pdr3p as well as the drug efflux pumps Pdr5p and Snq2p in S. cerevisiae or their counterparts in Candida albicans and Candida glabrata, named Cdr1p and Mdr1p, respectively. Importantly, CTBT also increased the sensitivity to fluconazole in multidrug-resistant cells overexpressing the efflux pumps. Yeast cells grown in the presence of subinhibitory concentrations of CTBT exhibited an altered sterol composition and a slightly enhanced accumulation of Rhodamine 6G, which suggests that the plasma membrane plays a role in sensitisation. This novel chemosensitisation by CTBT that can overcome multidrug resistance in yeast may prove useful in combined treatment of infections caused by drug-resistant fungal pathogens.

Original languageEnglish
Pages (from-to)170-178
Number of pages9
JournalInternational Journal of Antimicrobial Agents
Issue number2
Publication statusPublished - Feb 1 2007


  • Antifungal agents
  • Candida albicans
  • Candida glabrata
  • Chemosensitiser
  • Drug resistance
  • Saccharomyces cerevisiae
  • Yeast

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)

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