Autophagy-Related Pathways and Specific Role of Sterol Glucoside in Yeasts

Taras Y. Nazarko, Jean-Claude Farre, Andriy S. Polupanov, Andrei A. Sibirny and Suresh Subramani

volume 3 | issue 3

May/June 2007
Pages: 263 - 265

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Recently, we showed that the requirement of sterol glucoside (SG) during pexophagy in yeasts is dependent on the species and the nature of peroxisome inducers. Atg26, the enzyme that converts sterol to SG, is essential for degradation of very large methanol-induced peroxisomes, but only partly required for degradation of smaller-sized oleate- and amine-induced peroxisomes in Pichia pastoris. Moreover, oleate- and amine-induced peroxisomes of another yeast, Yarrowia lipolytica, are degraded by an Atg26-independent mechanism. The same is true for degradation of oleate-induced peroxisomes in Saccharomyces cerevisiae. Here, we review our findings on the specificity of Atg26 function in pexophagy and extend our observations to the role of SG in the cytoplasm to vacuole targeting (Cvt) pathway and bulk autophagy. The results presented here and elsewhere indicate that Atg26 might increase the efficacy of all autophagy-related pathways in P. pastoris, but not in other yeasts. Recently, it was shown that P. pastoris Atg26 (PpAtg26) is required for elongation of the pre-autophagosomal structure (PAS) into the micropexophagic membrane apparatus (MIPA) during micropexophagy. Therefore, we speculate that SG might facilitate elongation of any double membrane from the PAS and this enhancer function of SG becomes essential when extremely large double membranes are formed.

Addendum to:
The Requirement of Sterol Glucoside for Pexophagy in Yeast Is Dependent on the Species and Nature of Peroxisome Inducers
T.Y. Nazarko, A.S. Polupanov, R.R. Manjithaya, S. Subramani and A.A. Sibirny
Mol Biol Cell 2007; 18:106-18

Authors

Taras Y. Nazarko

University of California, San Diego

Jean-Claude Farre

Univsity of California, San Diego

Andriy S. Polupanov

National Academy of Sciences of Ukraine

Andrei A. Sibirny