title: Structure of a type IV pilus machinery in the open and closed state.
abstract: Proteins of the secretin family form large macromolecular complexes, which assemble in the outer membrane of Gram-negative bacteria. Secretins are major components of type II and III secretion systems and are linked to extrusion of type IV pili (T4P) and to DNA uptake. By electron cryo-tomography of whole Thermus thermophilus cells, we determined the in situ structure of a T4P molecular machine in the open and the closed state. Comparison reveals a major conformational change whereby the N-terminal domains of the central secretin PilQ shift by ~30 Å, and two periplasmic gates open to make way for pilus extrusion. Furthermore, we determine the structure of the assembled pilus.
authors.affiliation: Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
authors.forename: Vicki A M
authors.initials: VA
authors.lastname: Gold
authors.affiliation: Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Salzer
authors.affiliation: Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Averhoff
authors.affiliation: Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Kühlbrandt
mesh_terms: D020285:Cryoelectron Microscopy; D010861:Fimbriae, Bacterial / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000378:metabolism*; D011487:Protein Conformation; D012633:Secretin / Q000378:metabolism*; D016963:Thermus thermophilus / Q000737:chemistry*
chemical_list: D046912:Multiprotein Complexes; D012633:Secretin
keywords: DNA transporter; Thermus thermophilus; bacterial secretion; biophysics; electron cryo-tomography; structural biology; subtomogram averaging; type IV pilus