Selective degradation of peroxisomes in the yeast Hansenula polymorpha requires sterolglucosyltransferase Atg26

Abstract

UDP-glucose:sterol glucosyltransferase (EC 2.4.1.173) catalyses the biosynthesis of ergosterol glucoside, a minor membrane lipid present in yeasts and plants. The sterol glucosyltransferases from different yeast species, including the methylotrophic yeast Pichia pastoris, display narrow substrate specificity with respect to both activated sugar and glycosyl acceptor. We isolated the mutant of the methanol-utilizing yeast Hansenula polymorpha defective in the ATG26 gene (encoding sterol glucosyltransferase) and analysed its phenotype. Similarly to P. pastoris product of the H. polymorpha ATG26 gene was required for pexophagy, the process of selective autophagic peroxisome degradation in vacuoles. Thus, sterol glucosyltransferases in different species of methylotrophic yeasts have a similar function in pexophagic process probably related to peculiarities of peroxisome morphogenesis and regulation of their homeostasis in these yeasts.

Keywords

• methylotrophic yeasts
• hansenula polymorpha
• peroxisomes
• pexophagy
• sterol glucosyltransferase