title: Dimeric coiled-coil structure of Saccharomyces cerevisiae Atg16 and its functional significance in autophagy.
abstract: Atg16 interacts with the Atg12-Atg5 protein conjugate through its N-terminal domain and self-assembles through its coiled-coil domain (CCD). Formation of the Atg12-Atg5.Atg16 complex is essential for autophagy, the bulk degradation process conserved among most eukaryotes. Here, we report the crystal structures of full-length Saccharomyces cerevisiae Atg16 at 2.8 A resolution and its CCD at 2.5 A resolution. The CCD and full-length Atg16 each exhibit an extended alpha-helix, 90 and 130 A, respectively, and form a parallel coiled-coil dimer in the crystals. Although the apparent molecular weight of Atg16 observed by gel-filtration chromatography suggests that Atg16 is tetrameric, an analytical ultracentrifugation study showed Atg16 as a dimer in solution, consistent with the crystal structure. Evolutionary conserved surface residues clustered at the C-terminal half of Atg16 CCD were shown to be crucial for autophagy. These results will give a structural basis for understanding the molecular functions and significance of Atg16 in autophagy.
authors.affiliation: Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fujioka
authors.forename: Nobuo N
authors.initials: NN
authors.lastname: Noda
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakatogawa
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ohsumi
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Inagaki
mesh_terms: D001343:Autophagy / Q000502:physiology*; D000071192:Autophagy-Related Protein 12; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary / Q000502:physiology; D017433:Protein Structure, Secondary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: C491969:ATG12 protein, S cerevisiae; C498649:ATG16 protein, S cerevisiae; D000071192:Autophagy-Related Protein 12; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D029701:Saccharomyces cerevisiae Proteins