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In situ and high-resolution cryo-EM structure of a bacterial type VI secretion system membrane complex.
Journal article

In situ and high-resolution cryo-EM structure of a bacterial type VI secretion system membrane complex.

  • Rapisarda C CNRS UMR 5234 Microbiologie Fondamentale et Pathogénicité, Bordeaux, France.
  • Cherrak Y Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), UMR7255, Aix-Marseille Université - CNRS, Marseille, France.
  • Kooger R Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland.
  • Schmidt V Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), UMR7255, Aix-Marseille Université - CNRS, Marseille, France.
  • Pellarin R Institut Pasteur, Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR 3528, C3BI USR 3756, Paris, France.
  • Logger L Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), UMR7255, Aix-Marseille Université - CNRS, Marseille, France.
  • Cascales E Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), UMR7255, Aix-Marseille Université - CNRS, Marseille, France.
  • Pilhofer M Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland pilhofer@biol.ethz.ch edurand@imm.cnrs.fr edurand@inserm.fr r.fronzes@iecb.u-bordeaux.fr.
  • Durand E Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), UMR7255, INSERM, Marseille, France pilhofer@biol.ethz.ch edurand@imm.cnrs.fr edurand@inserm.fr r.fronzes@iecb.u-bordeaux.fr.
  • Fronzes R CNRS UMR 5234 Microbiologie Fondamentale et Pathogénicité, Bordeaux, France pilhofer@biol.ethz.ch edurand@imm.cnrs.fr edurand@inserm.fr r.fronzes@iecb.u-bordeaux.fr.
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  • 2019-03-17
Published in:
  • The EMBO journal. - 2019
cryo‐electron microscopy
membrane protein complex
type VI secretion systems
Bacterial Secretion Systems
Cell Membrane
Cryoelectron Microscopy
Escherichia coli
Escherichia coli Proteins
Membrane Proteins
Models, Molecular
Protein Binding
Protein Structure, Quaternary
Type VI Secretion Systems
English Bacteria have evolved macromolecular machineries that secrete effectors and toxins to survive and thrive in diverse environments. The type VI secretion system (T6SS) is a contractile machine that is related to Myoviridae phages. It is composed of a phage tail-like structure inserted in the bacterial cell envelope by a membrane complex (MC) comprising the TssJ, TssL and TssM proteins. We previously reported the low-resolution negative-stain electron microscopy structure of the enteroaggregative Escherichia coli MC and proposed a rotational 5-fold symmetry with a TssJ:TssL:TssM stoichiometry of 2:2:2. Here, cryo-electron tomography analyses of the T6SS MC confirm the 5-fold symmetry in situ and identify the regions of the structure that insert into the bacterial membranes. A high-resolution model obtained by single-particle cryo-electron microscopy highlights new features: five additional copies of TssJ, yielding a TssJ:TssL:TssM stoichiometry of 3:2:2, an 11-residue loop in TssM, protruding inside the lumen of the MC and constituting a functionally important periplasmic gate, and hinge regions. Based on these data, we propose an updated model on MC structure and dynamics during T6SS assembly and function.
Language
  • English
Open access status
hybrid
Identifiers
Persistent URL
https://sonar.ch/global/documents/275289
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