Modification of a ubiquitin-like protein Paz2 conducted micropexophagy through formation of a novel membrane structure

Mol Biol Cell. 2004 Jan;15(1):58-70. doi: 10.1091/mbc.e03-05-0340. Epub 2003 Sep 17.

Abstract

Microautophagy is a versatile process in which vacuolar or lysosomal membranes directly sequester cytosolic targets for degradation. Recent genetic evidence suggested that microautophagy uses molecular machineries essential for macroautophagy, but the details of this process are still unknown. In this study, a ubiquitin-like protein Paz2 essential for micropexophagy in the yeast Pichia pastoris has been shown to receive modification through the function of Paz8 and Gsa7, yielding a modified form Paz2-I, similar to the ubiquitin-like lipidation of Aut7 that is essential for macroautophagy in Saccharomyces cerevisiae. We identified a novel membrane structure formed after the onset of micropexophagy, which we suggest is necessary for the sequestration of peroxisomes by the vacuole. Assembly of this newly formed membrane structure, which is followed by localization of Paz2 to it, was found to require a properly functioning Paz2-modification system. We herein show that Paz2 and its modification system conduct micropexophagy through formation of the membrane structure, which explains the convergence between micropexophagy and macroautophagy with regard to de novo membrane formation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Autophagy-Related Protein 8 Family
  • Cell Compartmentation / physiology
  • Cloning, Molecular
  • Fungal Proteins / metabolism*
  • Intracellular Membranes / metabolism*
  • Intracellular Membranes / ultrastructure
  • Microscopy, Electron
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / genetics*
  • Models, Molecular
  • Molecular Sequence Data
  • Peroxisomes / metabolism*
  • Peroxisomes / ultrastructure
  • Pichia / cytology
  • Pichia / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid
  • Subcellular Fractions
  • Vacuoles / metabolism*
  • Vacuoles / ultrastructure

Substances

  • ATG8 protein, S cerevisiae
  • Autophagy-Related Protein 8 Family
  • Fungal Proteins
  • Microtubule-Associated Proteins
  • Saccharomyces cerevisiae Proteins