Genome microarray analysis of transcriptional activation in multidrug resistance yeast mutants

The cDNA from activated mutants of the homologous transcription factors Pdr 1p and Pdr3p was used to screen DNA microarrays of the Saccharomyces cerevi siae complete genome. Twenty-six overexpressed targets of the PDR1-3 and/or PDR3-7 mutants were identified. Twenty-one are new targets, the majority o f which are of unknown function. In addition to well known ABC transporters , these targets appear to be involved in transport or in membrane lipids an d cell wall biosyntheses. Several of the targets seem to contribute to the cell defence against a variety of stresses. Pdr1p and Pdr3p do not act simi larly on all targets, Unexpectedly, the expression of 23 other genes appear ed to be repressed in the PDR1-3 and/or PDR3-7 mutants. In contrast to the majority of the activated genes, none of the repressed genes contains pleio tropic drug resistance binding sites in their promoter. (C) 2000 Federation of European Biochemical Societies.