A single protease, Apg4B, is specific for the autophagy-related ubiquitin-like proteins GATE-16, MAP1-LC3, GABARAP, and Apg8L.
Apg8 is a ubiquitin-like protein involved in autophagy in yeast. Apg8 is covalently but transiently attached to membrane lipids through the actions of activating, conjugating, and processing/deconjugating enzymes. The mammalian Apg8 homologues GATE-16, GARARAP, and MAP1-LC3 have been implicated in intra-Golgi transport, receptor sorting, and autophagy, respectively. All are served by a single set of activating and conjugating enzymes. Here we identify a novel mammalian Apg8 homologue, which we name Apg8L, and describe the synthesis of electrophilic probes based on the GATE-16, GARARAP, MAP1-LC3, and Apg8L proteins. These probes not only form specific adducts in crude cell lysates, but also allow identification of the cellular proteases specific for the C termini of these Apg8 homologues. We find a single protease, Apg4B/autophagin-1, capable of acting on GATE-16, GABARAP, MAP1-LC3, and Apg8L. The Apg4B/autophagin-1 protease thus serves as a processing/deconjugating enzyme for these four highly divergent mammalian Apg8 homologues.
Hemelaar
Joris
J
Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Lelyveld
Victor S
VS
Kessler
Benedikt M
BM
Ploegh
Hidde L
HL
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D003598:Cytoskeletal Proteins; D020689:Exopeptidases / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D015335:Molecular Probes / Q000138:chemical synthesis; D011499:Protein Processing, Post-Translational; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017385:Sequence Homology; D014452:Ubiquitins / Q000378:metabolism
C113757:ATG8 protein, S cerevisiae; D051017:Apoptosis Regulatory Proteins; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C480861:GABARAP protein, mouse; C480859:Gabarapl1 protein, mouse; C407740:Gabarapl2 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; C480860:Map1lc3b protein, mouse; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D015335:Molecular Probes; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; D020689:Exopeptidases; C582881:Atg4b protein, mouse; D003546:Cysteine Endopeptidases