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The BC component of ABC toxins is an RHS-repeat-containing protein encapsulation device


The ABC toxin complexes produced by certain bacteria are of interest owing to their potent insecticidal activity1,2 and potential role in human disease3. These complexes comprise at least three proteins (A, B and C), which must assemble to be fully toxic4. The carboxy-terminal region of the C protein is the main cytotoxic component5, and is poorly conserved between different toxin complexes. A general model of action has been proposed, in which the toxin complex binds to the cell surface via the A protein, is endocytosed, and subsequently forms a pH-triggered channel, allowing the translocation of C into the cytoplasm, where it can cause cytoskeletal disruption in both insect and mammalian cells5. Toxin complexes have been visualized using single-particle electron microscopy6,7, but no high-resolution structures of the components are available, and the role of the B protein in the mechanism of toxicity remains unknown. Here we report the three-dimensional structure of the complex formed between the B and C proteins, determined to 2.5 Å by X-ray crystallography. These proteins assemble to form an unprecedented, large hollow structure that encapsulates and sequesters the cytotoxic, C-terminal region of the C protein like the shell of an egg. The shell is decorated on one end by a β-propeller domain, which mediates attachment of the B–C heterodimer to the A protein in the native complex. The structure reveals how C auto-proteolyses when folded in complex with B. The C protein is the first example, to our knowledge, of a structure that contains rearrangement hotspot (RHS) repeats8, and illustrates a marked structural architecture that is probably conserved across both this widely distributed bacterial protein family and the related eukaryotic tyrosine-aspartate (YD)-repeat-containing protein family, which includes the teneurins9. The structure provides the first clues about the function of these protein repeat families, and suggests a generic mechanism for protein encapsulation and delivery.

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Figure 1: Structure of the B–CNTR complex.
Figure 2: Auto-proteolysis of the C protein.
Figure 3: RHS repeat structure.
Figure 4: Position of the B–CNTR complex in the complete Yen-Tc particle.

Accession codes


Protein Data Bank

Data deposits

The atomic coordinates of the B–CNTR complex and the Chi2 chitinase have been deposited in the Protein Data Bank ( under the accession codes 4IGL and 4DWS, respectively.


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

    CAS  ADS  Article  PubMed  Google Scholar 

  2. ffrench-Constant, R. H. & Waterfield, N. R. Ground control for insect pests. Nature Biotechnol. 24, 660–661 (2006)

    CAS  Article  Google Scholar 

  3. Pinheiro, V. B. & Ellar, D. J. Expression and insecticidal activity of Yersinia pseudotuberculosis and Photorhabdus luminescens toxin complex proteins. Cell. Microbiol. 9, 2372–2380 (2007)

    CAS  Article  PubMed  Google Scholar 

  4. Waterfield, N., Hares, M., Yang, G., Dowling, A. & ffrench-Constant, R. Potentiation and cellular phenotypes of the insecticidal toxin complexes of Photorhabdus bacteria. Cell. Microbiol. 7, 373–382 (2005)

    CAS  Article  PubMed  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)

    CAS  ADS  Article  PubMed  Google Scholar 

  6. 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)

    CAS  ADS  Article  PubMed  PubMed Central  Google Scholar 

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

    CAS  ADS  Article  PubMed  Google Scholar 

  8. Hill, C. W., Sandt, C. H. & Vlazny, D. A. Rhs elements of Escherichia coli: a family of genetic composites each encoding a large mosaic protein. Mol. Microbiol. 12, 865–871 (1994)

    CAS  Article  PubMed  Google Scholar 

  9. Minet, A. D., Rubin, B. P., Tucker, R. P., Baumgartner, S. & Chiquet-Ehrismann, R. Teneurin-1, a vertebrate homologue of the Drosophila pair-rule gene ten-m, is a neuronal protein with a novel type of heparin-binding domain. J. Cell Sci. 112, 2019–2032 (1999)

    CAS  PubMed  Google Scholar 

  10. Hurst, M. R. H. et al. The main virulence determinant of Yersinia entomophaga MH96 is a broad-host-range toxin complex active against insects. J. Bacteriol. 193, 1966–1980 (2011)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  11. Zhang, D., de Souza, R. F., Anantharaman, V., Iyer, L. M. & Aravind, L. Polymorphic toxin systems: comprehensive characterization of trafficking modes, processing, mechanisms of action, immunity and ecology using comparative genomics. Biol. Direct 7, 18 (2012)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  12. Buetow, L., Flatau, G., Chiu, K., Boquet, P. & Ghosh, P. Structure of the Rho-activating domain of Escherichia coli cytotoxic necrotizing factor 1. Nature Struct. Biol. 8, 584–588 (2001)

    CAS  Article  PubMed  Google Scholar 

  13. Iyer, L. M., Zhang, D., Rogozin, I. B. & Aravind, L. Evolution of the deaminase fold and multiple origins of eukaryotic editing and mutagenic nucleic acid deaminases from bacterial toxin systems. Nucleic Acids Res. 39, 9473–9497 (2011)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  14. Jackson, A. P., Thomas, G. H., Parkhill, J. & Thomson, N. R. Evolutionary diversification of an ancient gene family (rhs) through C-terminal displacement. BMC Genomics 10, 584 (2009)

    Article  PubMed  PubMed Central  Google Scholar 

  15. Wang, Y. D., Zhao, S. & Hill, C. W. Rhs elements comprise three subfamilies which diverged prior to acquisition by Escherichia coli. J. Bacteriol. 180, 4102–4110 (1998)

    CAS  PubMed  PubMed Central  Google Scholar 

  16. Mosca, T. J., Hong, W., Dani, V. S., Favaloro, V. & Luo, L. Trans-synaptic Teneurin signalling in neuromuscular synapse organization and target choice. Nature 484, 237–241 (2012)

    CAS  ADS  Article  PubMed  PubMed Central  Google Scholar 

  17. Hong, W., Mosca, T. J. & Luo, L. Teneurins instruct synaptic partner matching in an olfactory map. Nature 484, 201–207 (2012)

    CAS  ADS  Article  PubMed  PubMed Central  Google Scholar 

  18. Feng, K. et al. All four members of the Ten-m/Odz family of transmembrane proteins form dimers. J. Biol. Chem. 277, 26128–26135 (2002)

    CAS  Article  PubMed  Google Scholar 

  19. Chand, D. et al. C-terminal processing of the teneurin proteins: Independent actions of a teneurin C-terminal associated peptide in hippocampal cells. Mol. Cell. Neurosci. 52, 38–50 (2013)

    CAS  Article  PubMed  Google Scholar 

  20. Tucker, R. P. & Chiquet-Ehrismann, R. Teneurins: a conserved family of transmembrane proteins involved in intercellular signaling during development. Dev. Biol. 290, 237–245 (2006)

    CAS  Article  PubMed  Google Scholar 

  21. Busby, J. N. et al. Structural analysis of Chi1 chitinase from Yen-Tc: the multisubunit insecticidal ABC toxin complex of Yersinia entomophaga. J. Mol. Biol. 415, 359–371 (2012)

    CAS  Article  PubMed  Google Scholar 

  22. Xu, Z., Horwich, A. L. & Sigler, P. B. The crystal structure of the asymmetric GroEL–GroES–(ADP)7 chaperonin complex. Nature 388, 741–750 (1997)

    CAS  ADS  Article  PubMed  Google Scholar 

  23. McPhillips, T. M. et al. Blu-Ice and the Distributed Control System: software for data acquisition and instrument control at macromolecular crystallography beamlines. J. Synchrotron Radiat. 9, 401–406 (2002)

    CAS  Article  PubMed  Google Scholar 

  24. Kabsch, W. XDS. Acta Crystallogr. D 66, 125–132 (2010)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  25. The. CCP4 suite. Programs for protein crystallography. Acta Crystallogr. D 50, 760–763 (1994)

  26. Panjikar, S., Parthasarathy, V., Lamzin, V. S., Weiss, M. S. & Tucker, P. A. Auto-rickshaw: an automated crystal structure determination platform as an efficient tool for the validation of an X-ray diffraction experiment. Acta Crystallogr. D 61, 449–457 (2005)

    Article  PubMed  Google Scholar 

  27. Panjikar, S., Parthasarathy, V., Lamzin, V. S., Weiss, M. S. & Tucker, P. A. On the combination of molecular replacement and single-wavelength anomalous diffraction phasing for automated structure determination. Acta Crystallogr. D 65, 1089–1097 (2009)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  28. Adams, P. D. et al. PHENIX: a comprehensive Python-based system for macromolecular structure solution. Acta Crystallogr. D 66, 213–221 (2010)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

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

    CAS  PubMed  Google Scholar 

  30. Orthaber, D., Bergmann, A. & Glatter, O. SAXS experiments on absolute scale with Kratky systems using water as a secondary standard. J. Appl. Crystallogr. 33, 218–225 (2000)

    CAS  Article  Google Scholar 

  31. Franke, D. & Svergun, D. I. DAMMIF, a program for rapid ab-initio shape determination in small-angle scattering. J. Appl. Crystallogr. 42, 342–346 (2009)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  32. Volkov, V. V. & Svergun, D. I. Uniqueness of ab initio shape determination in small-angle scattering. J. Appl. Crystallogr. 36, 860–864 (2003)

    CAS  Article  Google Scholar 

  33. Svergun, D. I. Restoring low resolution structure of biological macromolecules from solution scattering using simulated annealing. Biophys. J. 76, 2879–2886 (1999)

    CAS  ADS  Article  PubMed  PubMed Central  Google Scholar 

  34. Svergun, D., Barberato, C. & Koch, M. H. J. CRYSOL-a program to evaluate X-ray solution scattering of biological macromolecules from atomic coordinates. J. Appl. Crystallogr. 28, 768–773 (1995)

    CAS  Article  Google Scholar 

  35. Scheres, S. H. W., Nuñez-Ramirez, R., Sorzano, C. O. S., Carazo, J. M. & Marabini, R. Image processing for electron microscopy single-particle analysis using Xmipp. Nature Protocols 3, 977–990 (2008)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

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We are grateful to M. Sullivan, R. Kingston, T. Baker and many other members of the Structural Biology section at the University of Auckland for discussions, to V. Arcus for initial enthusiasm, and to B. Hankamer for provision of laboratory space at the University of Queensland and for mentorship. This work was supported by the New Zealand Foundation for Research, Science and Technology contract C10X0804, awarded to M.R.H.H. We would like to thank all beamline staff at the MX1, MX2 and SAXS/WAXS beamlines at the Australian Synchrotron for their support, and to the New Zealand Synchrotron Group Ltd for synchrotron access arrangements.

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Authors and Affiliations



J.N.B. cloned constructs, expressed, purified and crystallized proteins, collected and processed X-ray crystallography and SAXS data, and refined and analysed the protein structure; S.P. determined the protein structure; M.J.L. processed, refined and analysed negative-stain electron microscopy data; M.R.H.H. and J.S.L. designed the study; J.N.B. and J.S.L. wrote the paper and all authors discussed the results and contributed to the manuscript.

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Correspondence to Mark R. H. Hurst or J. Shaun Lott.

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Busby, J., Panjikar, S., Landsberg, M. et al. The BC component of ABC toxins is an RHS-repeat-containing protein encapsulation device. Nature 501, 547–550 (2013).

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