title: Structure of the dodecameric Yersinia enterocolitica secretin YscC and its trypsin-resistant core.
abstract: The type III secretion system machinery, also known as the injectisome, delivers bacterial effector proteins into eukaryotic cells during infection. The outer membrane YscC secretin is a major part of Yersinia enterocolitica's injectisome and is among the first components to assemble, solely assisted by its pilotin, YscW. We have determined the three-dimensional structures of the native complex and its protease-resistant core to 12 Å resolution by cryo-electron microscopy (cryo-EM) and show that YscC forms a dodecameric complex. Cryo-EM of YscC reconstituted into proteoliposomes defines the secretin's membrane-spanning region. Native YscC consists of an outer membrane ring connected via a thin cylindrical wall to a conical, periplasmic region that exposes N-terminal petals connected by flexible linkers. These petals harbor the binding site of YscD, a component of the inner membrane ring. A change in their orientation adapts the length of the YscC secretin and facilitates its interaction with YscD.
authors.affiliation: Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University Basel, Mattenstrasse 26, 4058 Basel, Switzerland.
authors.forename: Julia
authors.initials: J
authors.lastname: Kowal
authors.forename: Mohamed
authors.initials: M
authors.lastname: Chami
authors.forename: Philippe
authors.initials: P
authors.lastname: Ringler
authors.forename: Shirley A
authors.initials: SA
authors.lastname: Müller
authors.forename: Mikhail
authors.initials: M
authors.lastname: Kudryashev
authors.forename: Daniel
authors.initials: D
authors.lastname: Castaño-Díez
authors.forename: Marlise
authors.initials: M
authors.lastname: Amstutz
authors.forename: Guy R
authors.initials: GR
authors.lastname: Cornelis
authors.forename: Henning
authors.initials: H
authors.lastname: Stahlberg
authors.forename: Andreas
authors.initials: A
authors.lastname: Engel
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry; D008958:Models, Molecular; D009997:Osmotic Pressure; D011487:Protein Conformation; D055503:Protein Multimerization; D012633:Secretin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*; D015008:Yersinia enterocolitica / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008051:Lipid Bilayers; D012633:Secretin; D014357:Trypsin