Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A syringe-like injection mechanism in Photorhabdus luminescens toxins


Photorhabdus luminescens is an insect pathogenic bacterium that is symbiotic with entomopathogenic nematodes1. On invasion of insect larvae, P. luminescens is released from the nematodes and kills the insect through the action of a variety of virulence factors including large tripartite ABC-type toxin complexes2 (Tcs). Tcs are typically composed of TcA, TcB and TcC proteins and are biologically active only when complete3,4,5. Functioning as ADP-ribosyltransferases, TcC proteins were identified as the actual functional components that induce actin-clustering, defects in phagocytosis and cell death5,6,7. However, little is known about the translocation of TcC into the cell by the TcA and TcB components. Here we show that TcA in P. luminescens (TcdA1) forms a transmembrane pore and report its structure in the prepore and pore state determined by cryoelectron microscopy. We find that the TcdA1 prepore assembles as a pentamer forming an α-helical, vuvuzela-shaped channel less than 1.5 nanometres in diameter surrounded by a large outer shell. Membrane insertion is triggered not only at low pH as expected, but also at high pH, explaining Tc action directly through the midgut of insects8. Comparisons with structures of the TcdA1 pore inserted into a membrane and in complex with TcdB2 and TccC3 reveal large conformational changes during membrane insertion, suggesting a novel syringe-like mechanism of protein translocation. Our results demonstrate how ABC-type toxin complexes bridge a membrane to insert their lethal components into the cytoplasm of the host cell. We believe that the proposed mechanism is characteristic of the whole ABC-type toxin family. This explanation of toxin translocation is a step towards understanding the host–pathogen interaction and the complex life cycle of P. luminescens and other pathogens, including human pathogenic bacteria, and serves as a strong foundation for the development of biopesticides.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Cryoelectron microscopy structure of the TcdA1 prepore complex.
Figure 2: Cryoelectron microscopy structure of the TcdA1 pore and comparison with the prepore complex.
Figure 3: Structure of the PTC3 holotoxin complex.
Figure 4: Syringe-like mechanism for membrane insertion.

Accession codes

Data deposits

The coordinates for the electron microscopy structures have been deposited in EMDataBank under accession codes EMD-2297 to EMD-2301.


  1. Joyce, S. A., Watson, R. J. & Clarke, D. J. The regulation of pathogenicity and mutualism in Photorhabdus. Curr. Opin. Microbiol. 9, 127–132 (2006)

    CAS  Article  Google Scholar 

  2. ffrench-Constant, R. H. & Bowen, D. J. Novel insecticidal toxins from nematode-symbiotic bacteria. Cell. Mol. Life Sci. 57, 828–833 (2000)

    CAS  Article  Google Scholar 

  3. Waterfield, N. R., Bowen, D. J., Fetherston, J. D. & Perry, R. D. &. ffrench-Constant, R. H. The tc genes of Photorhabdus: a growing family. Trends Microbiol. 9, 185–191 (2001)

    CAS  Article  Google Scholar 

  4. Sheets, J. J. et al. Insecticidal toxin complex proteins from Xenorhabdus nematophilus: structure and pore formation. J. Biol. Chem. 286, 22742–22749 (2011)

    CAS  Article  Google Scholar 

  5. Lang, A. E. et al. Photorhabdus luminescens toxins ADP-ribosylate actin and RhoA to force actin clustering. Science 327, 1139–1142 (2010)

    ADS  CAS  Article  Google Scholar 

  6. Lang, A. E., Schmidt, G., Sheets, J. J. & Aktories, K. Targeting of the actin cytoskeleton by insecticidal toxins from Photorhabdus luminescens . Naunyn Schmiedebergs Arch. Pharmacol. 383, 227–235 (2011)

    CAS  Article  Google Scholar 

  7. Aktories, K., Lang, A. E., Schwan, C. & Mannherz, H. G. Actin as target for modification by bacterial protein toxins. FEBS J. 278, 4526–4543 (2011)

    CAS  Article  Google Scholar 

  8. Bowen, D. et al. Insecticidal toxins from the bacterium Photorhabdus luminescens . Science 280, 2129–2132 (1998)

    ADS  CAS  Article  Google Scholar 

  9. Landsberg, M. J. et al. 3D structure of the Yersinia entomophaga toxin complex and implications for insecticidal activity. Proc. Natl Acad. Sci. USA 108, 20544–20549 (2011)

    ADS  CAS  Article  Google Scholar 

  10. Young, J. A. T. & Collier, R. J. Anthrax toxin: receptor binding, internalization, pore formation, and translocation. Annu. Rev. Biochem. 76, 243–265 (2007)

    CAS  Article  Google Scholar 

  11. Katayama, H. et al. Three-dimensional structure of the anthrax toxin pore inserted into lipid nanodiscs and lipid vesicles. Proc. Natl Acad. Sci. USA 107, 3453–3457 (2010)

    ADS  CAS  Article  Google Scholar 

  12. Song, L. et al. Structure of staphylococcal α-hemolysin, a heptameric transmembrane pore. Science 274, 1859–1865 (1996)

    ADS  CAS  Article  Google Scholar 

  13. Geny, B. & Popoff, M. R. Bacterial protein toxins and lipids: pore formation or toxin entry into cells. Biol. Cell 98, 667–678 (2006)

    CAS  Article  Google Scholar 

  14. Parker, M. W. & Feil, S. C. Pore-forming protein toxins: from structure to function. Prog. Biophys. Mol. Biol. 88, 91–142 (2005)

    CAS  Article  Google Scholar 

  15. Iacovache, I., van der Goot, F. G. & Pernot, L. Pore formation: an ancient yet complex form of attack. Biochim. Biophys. Acta 1778, 1611–1623 (2008)

    CAS  Article  Google Scholar 

  16. Eifler, N. et al. Cytotoxin ClyA from Escherichia coli assembles to a 13-meric pore independent of its redox-state. EMBO J. 25, 2652–2661 (2006)

    CAS  Article  Google Scholar 

  17. Ramon, E. et al. Critical role of electrostatic interactions of amino acids at the cytoplasmic region of helices 3 and 6 in rhodopsin conformational properties and activation. J. Biol. Chem. 282, 14272–14282 (2007)

    CAS  Article  Google Scholar 

  18. Dow, J. A. Extremely high pH in biological systems: a model for carbonate transport. Am. J. Physiol. 246, R633–R636 (1984)

    CAS  PubMed  Google Scholar 

  19. Milstead, J. E. Heterorhabditis bacteriophora as a vector for introducing its associated bacterium into the hemocoel of Galleria mellonella larvae. J. Invertebr. Pathol. 33, 324–327 (1979)

    Article  Google Scholar 

  20. ffrench-Constant, R. et al. Photorhabdus: towards a functional genomic analysis of a symbiont and pathogen. FEMS Microbiol. Rev. 26, 433–456 (2003)

    CAS  Article  Google Scholar 

  21. Hohn, M. et al. SPARX, a new environment for cryo-EM image processing. J. Struct. Biol. 157, 47–55 (2007)

    CAS  Article  Google Scholar 

  22. Mindell, J. A. & Grigorieff, N. Accurate determination of local defocus and specimen tilt in electron microscopy. J. Struct. Biol. 142, 334–347 (2003)

    Article  Google Scholar 

  23. Adams, P. D. et al. The Phenix software for automated determination of macromolecular structures. Methods 55, 94–106 (2011)

    CAS  Article  Google Scholar 

  24. Rusu, M., Starosolski, Z., Wahle, M., Rigort, A. & Wriggers, W. Automated tracing of filaments in 3D electron tomography reconstructions using Sculptor and Situs. J. Struct. Biol. 178, 121–128 (2012)

    Article  Google Scholar 

  25. Pettersen, E. F. et al. UCSF Chimera–a visualization system for exploratory research and analysis. J. Comput. Chem. 25, 1605–1612 (2004)

    CAS  Article  Google Scholar 

Download references


We are grateful to R. S. Goody for continuous support and for comments on the manuscript. We thank I. Vetter for stimulating discussions. This work was supported by the Deutsche Forschungsgemeinschaft grants RA 1781/1-1 (S.R.) and AK 6/22-1 (K.A.) and by Max Planck Society (S.R.).

Author information

Authors and Affiliations



A.E.L. and V.P. cloned constructs and purified proteins; D.M. performed pH studies; A.E.L. and R.B. performed and analysed black lipid bilayer assays; C.G. screened samples and collected negative-stain electron microscopy data; C.G. and O.H. collected cryoelectron microscopy data; C.G. processed and refined electron microscopy data; C.G. and S.R. analysed electron microscopy data; K.A. and S.R. designed the study. C.G. and S.R. wrote the paper. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Stefan Raunser.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Figures 1-14, Supplementary Methods, Supplementary Table 1 and Supplementary References. (PDF 1909 kb)

Cryo-EM structure of the TcdA1 prepore complex

The video shows a simple linear interpolation between the negative stain and cryo-EM reconstruction of TcdA1. The two domains of the outer shell and the central pore are highlighted in green, khaki and yellow, respectively. In the end, the video focuses on the central pore and subsequently on a protomer, depicting the fitted α-helices. (MOV 5964 kb)

Morph between the negative stain EM reconstructions of TcdA1 in prepore and pore state

The video shows the two states in side and cut-away view and a simple linear interpolation between them. (MOV 4966 kb)

Syringe-like mechanism for membrane insertion

(Animated version of Fig. 4). The two domains of the outer shell and the central pore of TcdA1 are depicted in green, khaki and yellow, respectively. The dimeric complex of TcdB2 and TccC3 is depicted in orange. A brown bar indicates the membrane bilayer. (MOV 845 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Gatsogiannis, C., Lang, A., Meusch, D. et al. A syringe-like injection mechanism in Photorhabdus luminescens toxins. Nature 495, 520–523 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing