title: Dissecting the role of the Atg12-Atg5-Atg16 complex during autophagosome formation.
abstract: The activity of the conserved Atg12-Atg5-Atg16 complex is essential for autophagosome formation. However, little is known about its mechanism of action during this process. In our study we employed in vitro systems consisting of purified proteins and giant unilamellar vesicles (GUVs) or small liposomes to investigate membrane binding by the Atg12-Atg5-Atg16 complex and its interplay with the Atg8 conjugation system. We showed that Atg5 directly binds membranes and that this membrane binding is negatively regulated by Atg12 conjugation but activated by Atg16. Membrane binding by the Atg12-Atg5-Atg16 complex is required for efficient promotion of Atg8 lipidation. Additionally, we found that the Atg12-Atg5-Atg16 complex tethered vesicles in an Atg8-independent manner. In yeast, membrane binding by Atg5 is not required for its recruitment to the phagophore assembly site (PAS) but is essential for efficient promotion of autophagy and the cytoplasm-to-vacuole targeting (Cvt) pathway at a stage preceding Atg8 lipidation and autophagosome closure. Our findings provide new insights into the role of the Atg12-Atg5-Atg16 complex during autophagosome formation.
authors: Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.
authors: Marta
authors: M
authors: Walczak
authors: Sascha
authors: S
authors: Martens
mesh_terms: D001343:Autophagy; D000071192:Autophagy-Related Protein 12; D000071187:Autophagy-Related Protein 5; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D019281:Dimerization; D015966:Gene Expression Regulation, Fungal; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000502:physiology; D009154:Mutation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*
chemical_list: C491969:ATG12 protein, S cerevisiae; C498649:ATG16 protein, S cerevisiae; C102268:ATG5 protein, S cerevisiae; C113757:ATG8 protein, S cerevisiae; D000071192:Autophagy-Related Protein 12; D000071187:Autophagy-Related Protein 5; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D008055:Lipids; D008081:Liposomes; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; D044767:Ubiquitin-Protein Ligases
keywords: Atg12; Atg16; Atg5; Atg8; autophagosome; cytoplasm-to-vacuole targeting; phagophore assembly site