Propeptide of aminopeptidase 1 protein mediates aggregation and vesicle formation in cytoplasm-to-vacuole targeting pathway

J Biol Chem. 2012 Mar 23;287(13):10121-10133. doi: 10.1074/jbc.M111.311696. Epub 2011 Nov 28.


Misfolded protein aggregation causes disease and aging; autophagy counteracts this by eliminating damaged components, enabling cells to survive starvation. The cytoplasm-to-vacuole targeting pathway in yeast encompasses the aggregation of the premature form of aminopeptidase 1 (prApe1) in cytosol and its sequestration by autophagic proteins into a vesicle for vacuolar transport. We show that the propeptide of Ape1 is important for aggregation and vesicle formation and that it is sufficient for binding to prApe1 and Atg19. Defective aggregation disrupts vacuolar transport, suggesting that aggregate shape is important in vesicle formation, whereas Atg19 binding is not sufficient for vacuolar transport. Aggregation involves hydrophobicity, whereas Atg19 binding requires additional electrostatic interactions. Ape1 dodecamerization may cluster propeptides into trimeric structures, with sufficient affinity to form propeptide hexamers by binding to other dodecamers, causing aggregation. We show that Ape1 aggregates bind Atg19 and Atg8 in vitro; this could be used as a scaffold for an in vitro assay of autophagosome formation to elucidate the mechanisms of autophagy.

MeSH terms

  • Aminopeptidases / genetics
  • Aminopeptidases / metabolism*
  • Autophagy-Related Protein 8 Family
  • Autophagy-Related Proteins
  • Cytoplasm / enzymology*
  • Cytoplasm / genetics
  • Enzyme Precursors / genetics
  • Enzyme Precursors / metabolism*
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Protein Binding
  • Protein Multimerization / physiology
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Secretory Vesicles / enzymology*
  • Secretory Vesicles / genetics
  • Vacuoles / enzymology*
  • Vacuoles / genetics
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism


  • ATG19 protein, S cerevisiae
  • ATG8 protein, S cerevisiae
  • Autophagy-Related Protein 8 Family
  • Autophagy-Related Proteins
  • Enzyme Precursors
  • Microtubule-Associated Proteins
  • Receptors, Cell Surface
  • Saccharomyces cerevisiae Proteins
  • Vesicular Transport Proteins
  • Aminopeptidases
  • APE1 protein, S cerevisiae