In vitro systems for Atg8 lipidation.
Bottom Line: Among these are the components of two ubiquitin-like conjugation reactions that collectively mediate the conjugation of the ubiquitin-like Atg12 to the Atg5 protein and of the ubiquitin-like protein Atg8 to the headgroup of the membrane lipid phosphatidylethanolamine.The lipidated form of Atg8 is membrane-bound and marks the growing autophagosomal membrane as well as the completed autophagosome.The assays enable the study of the biochemical mechanisms of action of the Atg8 lipidation machinery and to analyze the impact of mutations and post-translational modifications of the conjugation machinery on Atg8 lipidation.
Affiliation: Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria.Show MeSH
Related in: MedlinePlus
Mentions: SUVs were prepared using an E. coli total extract (Avanti Polar Lipids, Inc., 100500C), which contains between 55% and 60% PE (weight/weight) for the assays shown in Figs. 2 and 3A. For the Atg4 deconjugation assay shown in Fig. 3B the SUVs were composed of 40% POPC, 35% POPS, 20% POPE, 5% PI3P. 100Â Î¼l of the lipid stock (10Â mg/ml) were transferred into a glass vial and dried under an argon stream. The dried lipids were further dried for an additional hour in a desiccator. Subsequently, the dried lipids were incubated with 1Â ml of 50Â mM HEPES, pH 7.5, 0.2Â mM DTT (or 1Â mM DTT for Fig. 3B) for 15Â min. The lipids were resuspended by tapping and gently sonicated for 2Â min in a water bath sonicator. The resuspended SUVs were then extruded 21Â times through 0.4Â Î¼m membrane followed by extrusion through a 0.1Â Î¼m membrane (Whatman, Nucleopore) using the Mini Extruder from Avanti Polar Lipids Inc. The final SUVs suspension has a concentration of 1Â mg lipids/ml buffer. SUVs are stable for 1â€“2Â days when stored at 4Â Â°C.
Affiliation: Max F. Perutz Laboratories, University of Vienna, Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria.