PY motifs of Rod1 are required for binding to Rsp5 and for drug resistance

In Saccharomyces cerevisiae, the overexpression of ROD1 confers resistance to o-dinitrobenzene (o-DNB), a representative of target drugs of glutathione S-transferase. The roles of Rod1 in drug resistance have remained to be determined. We isolated the rog3 mutation as a suppressor mutation of the temperature sensitivity of the strain, in that two of the total four glycogen synthase kinase 3 homologs were deleted. Rog3 is homologous to Rod1, and its overexpression also conferred resistance to o-DNB. Furthermore, these two proteins have PY-motifs, and bound to Rsp5, a hect-type ubiquitin ligase. The rsp5-101 mutant showed sensitivity to o-DNB as did the rod1 mutant, a mutant Rod1 containing altered PY motifs was defective in ability to bind to Rsp5 and in conferring o-DNB resistance. These results suggest that interaction of Rod1 and Rsp5 is important for drug resistance. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.