A PDR5-independent pathway of multi-drug resistance regulated by the SIN4 gene product

The SIN4 locus encodes a global transcriptional regulator of various yeast gents. In this report, we demonstrate that loss of function mutations in SI N4 create a multi-drug hypersensitive phenotype that is independent of PDR5 mediated resistance. Thus, double sin4, pdr5 mutants are mon sensitive tha n single mutants. Furthermore, SIN4 does not regulate the PDR5 locus. These observations establish that yeast cells have two genetically distinct path ways conferring resistance towards similar substrates. Copyright (C) 1999 J ohn Wiley & Sons, Ltd.