Atg15 in Saccharomyces cerevisiae consists of two functionally distinct domains

Mol Biol Cell. 2021 Apr 15;32(8):645-663. doi: 10.1091/mbc.E20-07-0500. Epub 2021 Feb 24.

Abstract

Autophagy is a cellular degradation system widely conserved among eukaryotes. During autophagy, cytoplasmic materials fated for degradation are compartmentalized in double membrane-bound organelles called autophagosomes. After fusing with the vacuole, their inner membrane-bound structures are released into the vacuolar lumen to become autophagic bodies and eventually degraded by vacuolar hydrolases. Atg15 is a lipase that is essential for disintegration of autophagic body membranes and has a transmembrane domain at the N-terminus and a lipase domain at the C-terminus. However, the roles of the two domains in vivo are not well understood. In this study, we found that the N-terminal domain alone can travel to the vacuole via the multivesicular body pathway, and that targeting of the C-terminal lipase domain to the vacuole is required for degradation of autophagic bodies. Moreover, we found that the C-terminal domain could disintegrate autophagic bodies when it was transported to the vacuole via the Pho8 pathway instead of the multivesicular body pathway. Finally, we identified H435 as one of the residues composing the putative catalytic triad and W466 as an important residue for degradation of autophagic bodies. This study may provide a clue to how the C-terminal lipase domain recognizes autophagic bodies to degrade them.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagosomes / metabolism
  • Autophagy / genetics
  • Autophagy-Related Proteins / genetics
  • Autophagy-Related Proteins / metabolism*
  • Autophagy-Related Proteins / physiology*
  • Biological Transport
  • Carboxylic Ester Hydrolases / genetics
  • Carboxylic Ester Hydrolases / metabolism*
  • Carboxylic Ester Hydrolases / physiology*
  • Cytoplasm / metabolism
  • Lipase / metabolism
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Membrane Glycoproteins / physiology*
  • Protein Domains
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology*
  • Vacuoles / metabolism
  • Vesicular Transport Proteins / metabolism

Substances

  • Autophagy-Related Proteins
  • Membrane Glycoproteins
  • Saccharomyces cerevisiae Proteins
  • Vesicular Transport Proteins
  • ATG15 protein, S cerevisiae
  • Carboxylic Ester Hydrolases
  • Lipase