Structure of VgrG1 in the Type VI secretion VgrG1-Tse6-EF-Tu complex embedded in lipid nanodiscs

Experimental Data Snapshot

  • Resolution: 3.25 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

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Mechanism of loading and translocation of type VI secretion system effector Tse6.

Quentin, D.Ahmad, S.Shanthamoorthy, P.Mougous, J.D.Whitney, J.C.Raunser, S.

(2018) Nat Microbiol 3: 1142-1152

  • DOI: https://doi.org/10.1038/s41564-018-0238-z
  • Primary Citation of Related Structures:  
    6H3L, 6H3N

  • PubMed Abstract: 

    The type VI secretion system (T6SS) primarily functions to mediate antagonistic interactions between contacting bacterial cells, but also mediates interactions with eukaryotic hosts. This molecular machine secretes antibacterial effector proteins by undergoing cycles of extension and contraction; however, how effectors are loaded into the T6SS and subsequently delivered to target bacteria remains poorly understood. Here, using electron cryomicroscopy, we analysed the structures of the Pseudomonas aeruginosa effector Tse6 loaded onto the T6SS spike protein VgrG1 in solution and embedded in lipid nanodiscs. In the absence of membranes, Tse6 stability requires the chaperone EagT6, two dimers of which interact with the hydrophobic transmembrane domains of Tse6. EagT6 is not directly involved in Tse6 delivery but is crucial for its loading onto VgrG1. VgrG1-loaded Tse6 spontaneously enters membranes and its toxin domain translocates across a lipid bilayer, indicating that effector delivery by the T6SS does not require puncturing of the target cell inner membrane by VgrG1. Eag chaperone family members from diverse Proteobacteria are often encoded adjacent to putative toxins with predicted transmembrane domains and we therefore anticipate that our findings will be generalizable to numerous T6SS-exported membrane-associated effectors.

  • Organizational Affiliation

    Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C
643Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: vgrG1PA0091
Find proteins for Q9I741 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore Q9I741 
Go to UniProtKB:  Q9I741
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9I741
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.25 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 
EM Software:
TaskSoftware PackageVersion

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
European Research CouncilGermany615984

Revision History  (Full details and data files)

  • Version 1.0: 2018-09-12
    Type: Initial release
  • Version 1.1: 2018-10-03
    Changes: Data collection, Database references
  • Version 1.2: 2024-05-15
    Changes: Data collection, Database references