Membrane insertion of α-xenorhabdolysin in near-atomic detail
- Max Planck Institute of Molecular Physiology, Germany
- The University of Texas, United States
Abstract
α-Xenorhabdolysins (Xax) are α-pore-forming toxins (α-PFT) that form 1-1.3 MDa large pore complexes to perforate the host cell membrane. PFTs are used by a variety of bacterial pathogens to attack host cells. Due to the lack of structural information, the molecular mechanism of action of Xax toxins is poorly understood. Here, we report the cryo-EM structure of the XaxAB pore complex from Xenorhabdus nematophila and the crystal structures of the soluble monomers of XaxA and XaxB. The structures reveal that XaxA and XaxB are built similarly and appear as heterodimers in the 12-15 subunits containing pore, classifying XaxAB as bi-component α-PFT. Major conformational changes in XaxB, including the swinging out of an amphipathic helix are responsible for membrane insertion. XaxA acts as an activator and stabilizer for XaxB that forms the actual transmembrane pore. Based on our results, we propose a novel structural model for the mechanism of Xax intoxication.
Data availability
The electron density map after post-processing has been deposited to the EMDB under accession code EMD-0088. The final model of XaxAB was submitted to the PDB under the accession code 6GY6. Coordinates of XaxA and XaxB in the soluble form have been deposited in the Protein Data Bank under accession codes PDB 6GY8 and PDB 6G47.
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Crystal structure of XaxA from Xenorhabdus nematophilaPublicly available at the RCSB Protein Data Bank (accession no: 6GY8).
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XaxAB pore complex from Xenorhabdus nematophilaPublicly available at the RCSB Protein Data Bank (accession no: EMD-0088, PDB ID 6GY6).
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Crystal structure of XaxB from Xenorhabdus nematophilaPublicly available at the RCSB Protein Data Bank (accession no: 6GY7.
Article and author information
Author details
Funding
Max-Planck-Gesellschaft (Open-access funding)
- Stefan Raunser
European Commission
- Stefan Raunser
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Schubert et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Membrane insertion of α-xenorhabdolysin in near-atomic detail
eLife 7:e38017.
https://doi.org/10.7554/eLife.38017
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