A series of 52 deletion mutant strains of Saccharomyces cerevisiae with increased sensitivity to numerous toxic compounds, including antifungals used in agriculture and medicine is available from BCCM/MUCL. These strains result from the systematic knockout analysis of multidrug efflux genes initiated and directed by André Goffeau, described in the PhD thesis of Anabelle Decottignies, 1998, Université catholique de Louvain, and in the articles by Rogers et al. (2001, J Mol Microbiol Biotechnol 3: 207-214), and Decottignies et al. (2002, in: Microbial Multidrug Efflux, I.T. Paulsen and K. Lewis, eds, Horizon Scientific Press, UK, pp 155-175).
Each strain bears single or multiple gene deletions of transcription factors and membrane-associated ABC transporters involved in pleiotropic drug resistance. A self-excisable gene disruption cassette has been used for sequential deletion of the Pdr1 and Pdr3 transcription activators and up to eight different ABC transporter proteins: the Pdr5 multidrug (cycloheximide) transporter, the Snq2 multidrug transporter involved in singlet oxygen species resistance, Pdr10 and Pdr15, all plasma membrane proteins of the pleiotropic drug resistance subfamily; the vacuolar Ycf1 metal resistance factor and the plasma membrane Yor1 exporter of organic anions and oligomycin from the conjugate transporter subfamilies I and II; the plasma membrane Pdr11 and Aus1 sterol transporters; and the vacuolar Vmr1 multidrug resistance transporter. These transporter genes were characterised by growth inhibition screens of hundreds of toxic compounds on the deleted strains that showed differential but overlapping substrate specificities. The pdr1-3 allele encodes a hyperactive mutated form of Pdr1p, resulting in increased levels of the ABC transporter proteins. Therefore, pdr1-3 strains are resistant to multiple drugs except for those accumulating in the cell as a consequence of the mutation of the cognate ABC transporter(s).
The ABC transporter proteins form one of the largest protein families known in almost all organisms from bacteria to mammals. They are of interest in various fields including virulence and drug resistance of microorganisms, herbicide resistance of plants, metabolic diseases and cancer treatment in humans (see Fig.). The deposited mutant strains are relevant for the discovery and engineering of novel antifungal drugs with potentially decreased susceptibility to ABC transporter-mediated efflux. This collection also constitutes a suitable system for the expression and purification of particular ABC transporter proteins.
The distribution of these yeast strains for non-commercial purposes has been assured by Prof. Stanislaw Ulaszewski (University of Wroclaw, Poland) and Prof. Michel Ghislain (Université catholique de Louvain, Belgium) in the past. They deposited a selection of the most frequently requested strains and the related genotype information at the BCCM/MUCL (Table) to assure their continued availability. The strains can be found in the BCCM/MUCL online catalogue nder the MUCL numbers 54103 to 54154.