Membrane insertion of α-xenorhabdolysin in near-atomic detail

  1. Evelyn Schubert
  2. Ingrid R Vetter
  3. Daniel Prumbaum
  4. Pawel A Penczek
  5. Stefan Raunser  Is a corresponding author
  1. Max Planck Institute of Molecular Physiology, Germany
  2. 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.

The following data sets were generated
    1. Raunser S
    2. Schubert E
    (2018) Crystal structure of XaxA from Xenorhabdus nematophila
    Publicly available at the RCSB Protein Data Bank (accession no: 6GY8).
    1. Raunser S
    2. Schubert E
    (2018) XaxAB pore complex from Xenorhabdus nematophila
    Publicly available at the RCSB Protein Data Bank (accession no: EMD-0088, PDB ID 6GY6).
    1. Raunser S
    2. Schubert E
    (2018) Crystal structure of XaxB from Xenorhabdus nematophila
    Publicly available at the RCSB Protein Data Bank (accession no: 6GY7.

Article and author information

Author details

  1. Evelyn Schubert

    Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
    Competing interests
    The authors declare that no competing interests exist.
  2. Ingrid R Vetter

    Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
    Competing interests
    The authors declare that no competing interests exist.
  3. Daniel Prumbaum

    Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
    Competing interests
    The authors declare that no competing interests exist.
  4. Pawel A Penczek

    Department of Biochemistry and Molecular Biology, The University of Texas, Houston, United States
    Competing interests
    The authors declare that no competing interests exist.
  5. Stefan Raunser

    Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
    For correspondence
    stefan.raunser@mpi-dortmund.mpg.de
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9373-3016

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.

Reviewing Editor

  1. Olga Boudker, Weill Cornell Medicine, United States

Publication history

  1. Received: May 2, 2018
  2. Accepted: July 15, 2018
  3. Accepted Manuscript published: July 16, 2018 (version 1)
  4. Version of Record published: August 10, 2018 (version 2)

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.

Metrics

  • 2,385
    Page views
  • 404
    Downloads
  • 19
    Citations

Article citation count generated by polling the highest count across the following sources: Crossref, PubMed Central, Scopus.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Evelyn Schubert
  2. Ingrid R Vetter
  3. Daniel Prumbaum
  4. Pawel A Penczek
  5. Stefan Raunser
(2018)
Membrane insertion of α-xenorhabdolysin in near-atomic detail
eLife 7:e38017.
https://doi.org/10.7554/eLife.38017

Further reading

    1. Microbiology and Infectious Disease
    Pengge Qian et al.
    Research Article

    Malaria is caused by infection of the erythrocytes by the parasites Plasmodium. Inside the erythrocytes, the parasites multiply via schizogony, an unconventional cell division mode. The Inner Membrane Complex (IMC), an organelle located beneath the parasite plasma membrane, serving as the platform for protein anchorage, is essential for schizogony. So far, complete repertoire of IMC proteins and their localization determinants remain unclear. Here we used biotin ligase (TurboID)-based proximity labelling to compile the proteome of the schizont IMC of rodent malaria parasite Plasmodium yoelii. In total, 300 TurboID-interacting proteins were identified. 18 of 21 selected candidates were confirmed to localize in the IMC, indicating good reliability. In light of the existing palmitome of Plasmodium falciparum, 83 proteins of the P. yoelii IMC proteome are potentially palmitoylated. We further identified DHHC2 as the major resident palmitoyl-acyl-transferase of the IMC. Depletion of DHHC2 led to defective schizont segmentation and growth arrest both in vitro and in vivo. DHHC2 was found to palmitoylate two critical IMC proteins CDPK1 and GAP45 for their IMC localization. In summary, this study reports an inventory of new IMC proteins and demonstrates a central role of DHHC2 in governing IMC localization of proteins during the schizont development.

    1. Microbiology and Infectious Disease
    Claudia A Vera-Arias et al.
    Research Article Updated

    Most rapid diagnostic tests for Plasmodium falciparum malaria target the Histidine-Rich Proteins 2 and 3 (HRP2 and HRP3). Deletions of the hrp2 and hrp3 genes result in false-negative tests and are a threat for malaria control. A novel assay for molecular surveillance of hrp2/hrp3 deletions was developed based on droplet digital PCR (ddPCR). The assay quantifies hrp2, hrp3, and a control gene with very high accuracy. The theoretical limit of detection was 0.33 parasites/µl. The deletion was reliably detected in mixed infections with wild-type and hrp2-deleted parasites at a density of >100 parasites/reaction. For a side-by-side comparison with the conventional nested PCR (nPCR) assay, 248 samples were screened in triplicate by ddPCR and nPCR. No deletions were observed by ddPCR, while by nPCR hrp2 deletion was observed in 8% of samples. The ddPCR assay was applied to screen 830 samples from Kenya, Zanzibar/Tanzania, Ghana, Ethiopia, Brazil, and Ecuador. Pronounced differences in the prevalence of deletions were observed among sites, with more hrp3 than hrp2 deletions. In conclusion, the novel ddPCR assay minimizes the risk of false-negative results (i.e., hrp2 deletion observed when the sample is wild type), increases sensitivity, and greatly reduces the number of reactions that need to be run.