Analysis of
two autophagy deficient mutants of the yeast Yarrowia lipolytica.
Iryna Parshyna,
Carola Hoffmann, Gerold Barth
Institut für Mikrobiologie, Technische Universität Dresden, Mommsenstr. 13,
Dresden, 01062, Germany (ip3@rcs.urz.tu-dresden.de)
Specific degradation of proteins in response to changing environmental conditions is an important aspect of cellular survival. In some methylotrophic yeasts like Hansenula polymorpha and Pichia pastoris the level of peroxisomal proteins are strongly regulated when different nutritional conditions are used. When acetate/oleate/ethylamine-grown cells of Yarrowia lipolytica are switched to glucose/ammonium sulphate-containing medium, peroxisomal proteins such as isocitrate lyase and thiolase are selectively degraded (Gunkel et al., 1999). To elucidate the molecular mechanism of selective peroxisome degradation in this yeast we examined uptake of peroxisomal proteins in mutants known to be defective in general as well as in specialised autophagic processes in other yeast species (Mukayama et. al., 2002). Two autophagy deficient mutants of Y. lipolytica were constructed using gene disruption technique. The obtained integrative transformants express chimerical lacZ-eGFP(SKL) protein that was shown previously to be degraded like a peroxisomal one under the conditions of peroxisome degradation (Parshyna and Barth, 2003, in press). The properties of the mutants will be discussed.