Early Steps in Autophagy Depend on Direct Phosphorylation of Atg9 by the Atg1 Kinase

Mol Cell. 2014 Feb 6;53(3):471-83. doi: 10.1016/j.molcel.2013.12.011. Epub 2014 Jan 16.

Abstract

Bulk degradation of cytoplasmic material is mediated by a highly conserved intracellular trafficking pathway termed autophagy. This pathway is characterized by the formation of double-membrane vesicles termed autophagosomes engulfing the substrate and transporting it to the vacuole/lysosome for breakdown and recycling. The Atg1/ULK1 kinase is essential for this process; however, little is known about its targets and the means by which it controls autophagy. Here we have screened for Atg1 kinase substrates using consensus peptide arrays and identified three components of the autophagy machinery. The multimembrane-spanning protein Atg9 is a direct target of this kinase essential for autophagy. Phosphorylated Atg9 is then required for the efficient recruitment of Atg8 and Atg18 to the site of autophagosome formation and subsequent expansion of the isolation membrane, a prerequisite for a functioning autophagy pathway. These findings show that the Atg1 kinase acts early in autophagy by regulating the outgrowth of autophagosomal membranes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Aminopeptidases / chemistry
  • Aminopeptidases / metabolism
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / metabolism
  • Autophagy / physiology*
  • Autophagy-Related Proteins
  • Binding Sites
  • Consensus Sequence
  • Intracellular Membranes / metabolism
  • Mass Spectrometry
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Membrane Proteins / physiology
  • Molecular Sequence Data
  • Phagosomes / metabolism
  • Phosphorylation
  • Protein Kinases / metabolism
  • Protein Kinases / physiology*
  • Saccharomyces cerevisiae / cytology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology*

Substances

  • ATG18 protein, S cerevisiae
  • ATG9 protein, S cerevisiae
  • Arabidopsis Proteins
  • Autophagy-Related Proteins
  • Membrane Proteins
  • Saccharomyces cerevisiae Proteins
  • Protein Kinases
  • ATG1 protein, S cerevisiae
  • Aminopeptidases
  • Atg2 protein, Arabidopsis