Vacuolar accumulation and extracellular extrusion of electrophilic compounds by wild-type and glutathione-deficient mutants of the methylotrophic yeast Hansenula polymorpha.

The methylotrophic yeast Hansenula polymorpha CBS4732 leu2 detoxifies electrophilic xenobiotics by glutathione (GSH)-dependent accumulation in vacuoles, as shown by fluorescence microscopy. GSH-dependent and GSH-independent export of xenobiotic derivatives were also demonstrated by high-performance liquid chromatography (HPLC). Conjugates of GSH and N-acetylcysteine with monobromobimane and N-[1-pyrene]maleimide were observed among the HPLC fractions, along with unidentified derivatives.