title: The In Vivo Architecture of the Exocyst Provides Structural Basis for Exocytosis.
abstract: The structural characterization of protein complexes in their native environment is challenging but crucial for understanding the mechanisms that mediate cellular processes. We developed an integrative approach to reconstruct the 3D architecture of protein complexes in vivo. We applied this approach to the exocyst, a hetero-octameric complex of unknown structure that is thought to tether secretory vesicles during exocytosis with a poorly understood mechanism. We engineered yeast cells to anchor the exocyst on defined landmarks and determined the position of its subunit termini at nanometer precision using fluorescence microscopy. We then integrated these positions with the structural properties of the subunits to reconstruct the exocyst together with a vesicle bound to it. The exocyst has an open hand conformation made of rod-shaped subunits that are interlaced in the core. The exocyst architecture explains how the complex can tether secretory vesicles, placing them in direct contact with the plasma membrane.
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany; Department of Biochemistry and NCCR Chemical Biology, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Picco
authors.affiliation: Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany and Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo de Olavide-CSIC, Carretera de Utrera km1, 41013 Sevilla, Spain.
authors.forename: Ibai
authors.initials: I
authors.lastname: Irastorza-Azcarate
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Specht
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Böke
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, c/ Baldiri Reixac 10, 08028 Barcelona, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Pazos
authors.affiliation: Department of Biochemistry and NCCR Chemical Biology, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva, Switzerland.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Rivier-Cordey
authors.affiliation: Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany and Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo de Olavide-CSIC, Carretera de Utrera km1, 41013 Sevilla, Spain. Electronic address: damienpdevos@gmail.com.
authors.forename: Damien P
authors.initials: DP
authors.lastname: Devos
authors.affiliation: Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany; Department of Biochemistry and NCCR Chemical Biology, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva, Switzerland. Electronic address: marko.kaksonen@unige.ch.
authors.forename: Marko
authors.initials: M
authors.lastname: Kaksonen
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, c/ Baldiri Reixac 10, 08028 Barcelona, Spain. Electronic address: oriol.gallego@irbbarcelona.org.
authors.forename: Oriol
authors.initials: O
authors.lastname: Gallego
mesh_terms: D005089:Exocytosis; D006056:Golgi Apparatus / Q000378:metabolism; D008958:Models, Molecular; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism
keywords: PICT; SHREC; Vesicle trafficking; architecture of protein complexes; exocyst; exocytosis; fluorescence localization; fluorescence microscopy; integrative structural biology; in vivo structure