Cdc48/p97 and Shp1/p47 regulate autophagosome biogenesis in concert with ubiquitin-like Atg8.
The molecular details of the biogenesis of double-membraned autophagosomes are poorly understood. We identify the Saccharomyces cerevisiae AAA-adenosine triphosphatase Cdc48 and its substrate-recruiting cofactor Shp1/Ubx1 as novel components needed for autophagosome biogenesis. In mammals, the Cdc48 homologue p97/VCP and the Shp1 homologue p47 mediate Golgi reassembly by extracting an unknown monoubiquitinated fusion regulator from a complex. We find no requirement of ubiquitination or the proteasome system for autophagosome biogenesis but detect interaction of Shp1 with the ubiquitin-fold autophagy protein Atg8. Atg8 coupled to phosphatidylethanolamine (PE) is crucial for autophagosome elongation and, in vitro, mediates tethering and hemifusion. Interaction with Shp1 requires an FK motif within the N-terminal non-ubiquitin-like Atg8 domain. Based on our data, we speculate that autophagosome formation, in contrast to Golgi reassembly, requires a complex in which Atg8 functionally substitutes ubiquitin. This, for the first time, would give a rationale for use of the ubiquitin-like Atg8 during macroautophagy and would explain why Atg8-PE delipidation is necessary for efficient macroautophagy.
Krick
Roswitha
R
Department of Biochemistry II, Georg-August University, D-37073 Goettingen, Germany.
Bremer
Sebastian
S
Welter
Evelyn
E
Schlotterhose
Petra
P
Muehe
Yvonne
Y
Eskelinen
Eeva-Liisa
EL
Thumm
Michael
M
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D010588:Phagosomes / Q000201:enzymology* / Q000648:ultrastructure; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D000074405:Valosin Containing Protein
C113757:ATG8 protein, S cerevisiae; D000071190:Autophagy-Related Protein 8 Family; D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; C106691:SHP1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein