Membrane Binding and Homodimerization of Atg16 Via Two Distinct Protein Regions is Essential for Autophagy in Yeast |
| |
Affiliation: | 1. Department of Structural Biology, Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan;2. Institute of Microbial Chemistry (BIKAKEN), Tokyo 141-0021, Japan;3. Research Center for Cell Biology, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan |
| |
Abstract: | Macroautophagy is a bulk degradation mechanism in eukaryotic cells. Efficiency of an essential step of this process in yeast, Atg8 lipidation, relies on the presence of Atg16, a subunit of the Atg12–Atg5-Atg16 complex acting as the E3-like enzyme in the ubiquitination-like reaction. A current view on the functional structure of Atg16 in the yeast S. cerevisiae comes from the two crystal structures that reveal the Atg5-interacting α-helix linked via a flexible linker to another α-helix of Atg16, which then assembles into a homodimer. This view does not explain the results of previous in vitro studies revealing Atg16-dependent deformations of membranes and liposome-binding of the Atg12–Atg5 conjugate upon addition of Atg16. Here we show that Atg16 acts as both a homodimerizing and peripheral membrane-binding polypeptide. These two characteristics are imposed by the two distinct regions that are disordered in the nascent protein. Atg16 binds to membranes in vivo via the amphipathic α-helix (amino acid residues 113–131) that has a coiled-coil-like propensity and a strong hydrophobic face for insertion into the membrane. The other protein region (residues 64–99) possesses a coiled-coil propensity, but not amphipathicity, and is dispensable for membrane anchoring of Atg16. This region acts as a Leu-zipper essential for formation of the Atg16 homodimer. Mutagenic disruption in either of these two distinct domains renders Atg16 proteins that, in contrast to wild type, completely fail to rescue the autophagy-defective phenotype of atg16Δ cells. Together, the results of this study yield a model for the molecular mechanism of Atg16 function in macroautophagy. |
| |
Keywords: | amphipathic helix coiled-coil liposome sedimentation protein intrinsic disorder subcellular fractionation Atg" },{" #name" :" keyword" ," $" :{" id" :" k0035" }," $$" :[{" #name" :" text" ," _" :" autophagy-related MKO" },{" #name" :" keyword" ," $" :{" id" :" k0045" }," $$" :[{" #name" :" text" ," _" :" multiple-knockout PAS" },{" #name" :" keyword" ," $" :{" id" :" k0055" }," $$" :[{" #name" :" text" ," _" :" phagophore assembly site PE" },{" #name" :" keyword" ," $" :{" id" :" k0065" }," $$" :[{" #name" :" text" ," _" :" phosphatidylethanolamine PtdIns3P" },{" #name" :" keyword" ," $" :{" id" :" k0075" }," $$" :[{" #name" :" text" ," _" :" phosphatidylinositol-3-phosphate SUV" },{" #name" :" keyword" ," $" :{" id" :" k0085" }," $$" :[{" #name" :" text" ," _" :" small unilamellar vesicles TCA" },{" #name" :" keyword" ," $" :{" id" :" k0095" }," $$" :[{" #name" :" text" ," _" :" trichloroacetic acid YPL" },{" #name" :" keyword" ," $" :{" id" :" k0105" }," $$" :[{" #name" :" text" ," _" :" yeast polar lipids |
本文献已被 ScienceDirect 等数据库收录! |
|