title: Structural insights into the functional cycle of the ATPase module of the 26S proteasome.
abstract: In eukaryotic cells, the ubiquitin-proteasome system (UPS) is responsible for the regulated degradation of intracellular proteins. The 26S holocomplex comprises the core particle (CP), where proteolysis takes place, and one or two regulatory particles (RPs). The base of the RP is formed by a heterohexameric AAA+ATPase module, which unfolds and translocates substrates into the CP. Applying single-particle cryo-electron microscopy (cryo-EM) and image classification to samples in the presence of different nucleotides and nucleotide analogs, we were able to observe four distinct conformational states (s1 to s4). The resolution of the four conformers allowed for the construction of atomic models of the AAA+ATPase module as it progresses through the functional cycle. In a hitherto unobserved state (s4), the gate controlling access to the CP is open. The structures described in this study allow us to put forward a model for the 26S functional cycle driven by ATP hydrolysis.
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Wehmer
authors.affiliation: Beckman Institute, Center for the Physics of Living Cells, University of Illinois, Urbana-Champaign, Urbana, IL 61801.
authors.forename: Till
authors.initials: T
authors.lastname: Rudack
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Beck
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Aufderheide
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Pfeifer
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
authors.forename: Jürgen M
authors.initials: JM
authors.lastname: Plitzko
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.|Bijvoet Center for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Förster
authors.affiliation: Beckman Institute, Center for the Physics of Living Cells, University of Illinois, Urbana-Champaign, Urbana, IL 61801.
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; baumeist@biochem.mpg.de sakata@biochem.mpg.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
authors.affiliation: Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; baumeist@biochem.mpg.de sakata@biochem.mpg.de.
authors.forename: Eri
authors.initials: E
authors.lastname: Sakata
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry*; D020285:Cryoelectron Microscopy; D008958:Models, Molecular; D009711:Nucleotides / Q000737:chemistry; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000648:ultrastructure; D011487:Protein Conformation
chemical_list: D009711:Nucleotides; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000251:Adenosine Triphosphatases
keywords: 26S proteasome; AAA+ ATPase; cryo-electron microscopy; integrative modeling; single-particle analysis