Early steps in autophagy depend on direct phosphorylation of Atg9 by the Atg1 kinase.
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.
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Daniel
D
Papinski
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Martina
M
Schuschnig
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Wolfgang
W
Reiter
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Larissa
L
Wilhelm
Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, Wolfgang Pauli Strasse 16, 8093 Zürich, Switzerland.
Christopher A
CA
Barnes
Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, Wolfgang Pauli Strasse 16, 8093 Zürich, Switzerland.
Alessio
A
Maiolica
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Isabella
I
Hansmann
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Thaddaeus
T
Pfaffenwimmer
Institute of Biochemistry, Department of Biology, ETH Zürich, Schafmattstrasse 18, 8093 Zürich, Switzerland.
Monika
M
Kijanska
Institute of Biochemistry, Department of Biology, ETH Zürich, Schafmattstrasse 18, 8093 Zürich, Switzerland.
Ingrid
I
Stoffel
Institute of Biochemistry, Department of Biology, ETH Zürich, Schafmattstrasse 18, 8093 Zürich, Switzerland.
Sung Sik
SS
Lee
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Andrea
A
Brezovich
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
Jane Hua
JH
Lou
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
Benjamin E
BE
Turk
Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, Wolfgang Pauli Strasse 16, 8093 Zürich, Switzerland.
Ruedi
R
Aebersold
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.
Gustav
G
Ammerer
Institute of Biochemistry, Department of Biology, ETH Zürich, Schafmattstrasse 18, 8093 Zürich, Switzerland.
Matthias
M
Peter
Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria. Electronic address: claudine.kraft@univie.ac.at.
Claudine
C
Kraft
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000737:chemistry / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism; D001343:Autophagy / Q000502:physiology*; D000071183:Autophagy-Related Proteins; D001665:Binding Sites; D016384:Consensus Sequence; D007425:Intracellular Membranes / Q000378:metabolism; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D010588:Phagosomes / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*
C441008:ATG18 protein, S cerevisiae; C434065:ATG9 protein, S cerevisiae; D029681:Arabidopsis Proteins; D000071183:Autophagy-Related Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C477823:ATG1 protein, S cerevisiae; D000626:Aminopeptidases; C518661:Atg2 protein, Arabidopsis