6SUF

Structure of Photorhabdus luminescens Tc holotoxin pore


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 3.4 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure of a Tc holotoxin pore provides insights into the translocation mechanism.

Roderer, D.Hofnagel, O.Benz, R.Raunser, S.

(2019) Proc.Natl.Acad.Sci.USA 116: 23083-23090

  • DOI: 10.1073/pnas.1909821116
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Tc toxins are modular toxin systems of insect and human pathogenic bacteria. They are composed of a 1.4-MDa pentameric membrane translocator (TcA) and a 250-kDa cocoon (TcB and TcC) encapsulating the 30-kDa toxic enzyme (C terminus of TcC). Binding o ...

    Tc toxins are modular toxin systems of insect and human pathogenic bacteria. They are composed of a 1.4-MDa pentameric membrane translocator (TcA) and a 250-kDa cocoon (TcB and TcC) encapsulating the 30-kDa toxic enzyme (C terminus of TcC). Binding of Tc toxins to target cells and a pH shift trigger the conformational transition from the soluble prepore state to the membrane-embedded pore. Subsequently, the toxic enzyme is translocated and released into the cytoplasm. A high-resolution structure of a holotoxin embedded in membranes is missing, leaving open the question of whether TcB-TcC has an influence on the conformational transition of TcA. Here we show in atomic detail a fully assembled 1.7-MDa Tc holotoxin complex from Photorhabdus luminescens in the membrane. We find that the 5 TcA protomers conformationally adapt to fit around the cocoon during the prepore-to-pore transition. The architecture of the Tc toxin complex allows TcB-TcC to bind to an already membrane-embedded TcA pore to form a holotoxin. Importantly, assembly of the holotoxin at the membrane results in spontaneous translocation of the toxic enzyme, indicating that this process is not driven by a proton gradient or other energy source. Mammalian lipids with zwitterionic head groups are preferred over other lipids for the integration of Tc toxins. In a nontoxic Tc toxin variant, we can visualize part of the translocating toxic enzyme, which transiently interacts with alternating negative charges and hydrophobic stretches of the translocation channel, providing insights into the mechanism of action of Tc toxins.


    Organizational Affiliation

    Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.,Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany; raunser@mpi-dortmund.mpg.de.,Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
TcdA1
A, B, C, D, E
2516Photorhabdus luminescensMutation(s): 0 
Gene Names: tcdA (tcdA1)
Find proteins for Q9RN43 (Photorhabdus luminescens)
Go to UniProtKB:  Q9RN43
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
TcdB2,TccC3
F
2439Photorhabdus luminescensMutation(s): 0 
Gene Names: TccC3, tcdB2
Find proteins for Q8GF97 (Photorhabdus luminescens)
Go to UniProtKB:  Q8GF97
Find proteins for Q8GF99 (Photorhabdus luminescens)
Go to UniProtKB:  Q8GF99
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 3.4 Å
  • Aggregation State: PARTICLE 
  • Reconstruction Method: SINGLE PARTICLE 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
European Research CouncilGermany615984

Revision History 

  • Version 1.0: 2019-11-06
    Type: Initial release
  • Version 1.1: 2019-11-13
    Type: Data collection, Database references
  • Version 1.2: 2019-11-20
    Type: Database references