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Structure and function of the Salmonella Typhi chimaeric A2B5 typhoid toxin



Salmonella enterica serovar Typhi (S. Typhi) differs from most other salmonellae in that it causes a life-threatening systemic infection known as typhoid fever1. The molecular bases for its unique clinical presentation are unknown2. Here we find that the systemic administration of typhoid toxin, a unique virulence factor of S. Typhi, reproduces many of the acute symptoms of typhoid fever in an animal model. We identify specific carbohydrate moieties on specific surface glycoproteins that serve as receptors for typhoid toxin, which explains its broad cell target specificity. We present the atomic structure of typhoid toxin, which shows an unprecedented A2B5 organization with two covalently linked A subunits non-covalently associated to a pentameric B subunit. The structure provides insight into the toxin’s receptor-binding specificity and delivery mechanisms and reveals how the activities of two powerful toxins have been co-opted into a single, unique toxin that can induce many of the symptoms characteristic of typhoid fever. These findings may lead to the development of potentially life-saving therapeutics against typhoid fever.

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Figure 1: Systemic administration of typhoid toxin causes symptoms observed during the acute phase of typhoid fever.
Figure 2: Typhoid toxin recognizes terminally sialylated glycans on surface glycoproteins.
Figure 3: The crystal structure of typhoid toxin depicts a unique architecture.
Figure 4: Structure-function analysis of typhoid toxin.

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  1. Parry, C. M., Hien, T. T., Dougan, G., White, N. J. & Farrar, J. J. Typhoid fever. N. Engl. J. Med. 347, 1770–1782 (2002)

    CAS  Article  PubMed  Google Scholar 

  2. Parkhill, J. et al. Complete genome sequence of a multiple drug resistant Salmonella enterica serovar Typhi CT18. Nature 413, 848–852 (2001)

    ADS  CAS  Article  PubMed  Google Scholar 

  3. Butler, T. Treatment of typhoid fever in the 21st century: promises and shortcomings. Clin. Microbiol. Infect. 17, 959–963 (2011)

    CAS  Article  PubMed  Google Scholar 

  4. Crump, J. A. & Mintz, E. D. Global trends in typhoid and paratyphoid fever. Clin. Infect. Dis. 50, 241–246 (2010)

    Article  PubMed  Google Scholar 

  5. Sabbagh, S. C., Forest, C. G., Lepage, C., Leclerc, J. & Daigle, F. So similar, yet so different: uncovering distinctive features in the genomes of Salmonella enterica serovars Typhimurium and Typhi. FEMS Microbiol. Lett. 305, 1–13 (2010)

    CAS  Article  PubMed  Google Scholar 

  6. Haghjoo, E. & Galán, J. E. Salmonella typhi encodes a functional cytolethal distending toxin that is delivered into host cells by a bacterial-internalization pathway. Proc. Natl Acad. Sci. USA 101, 4614–4619 (2004)

    ADS  CAS  Article  PubMed  PubMed Central  Google Scholar 

  7. Spanò, S., Ugalde, J. E. & Galán, J. E. Delivery of a Salmonella Typhi exotoxin from a host intracellular compartment. Cell Host Microbe 3, 30–38 (2008)

    Article  PubMed  Google Scholar 

  8. Spanò, S. & Galán, J. E. A novel pathway for exotoxin delivery by an intracellular pathogen. Curr. Opin. Microbiol. 11, 15–20 (2008)

    Article  PubMed  PubMed Central  Google Scholar 

  9. Beddoe, T., Paton, A., Le Nours, J., Rossjohn, J. & Paton, J. Structure, biological functions and applications of the AB5 toxins. Trends Biochem. Sci. 35, 411–418 (2010)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  10. Lara-Tejero, M. & Galán, J. E. A bacterial toxin that controls cell cycle progression as a deoxyribonuclease I-like protein. Science 290, 354–357 (2000)

    ADS  CAS  Article  PubMed  Google Scholar 

  11. Lara-Tejero, M. & Galán, J. E. Cytolethal distending toxin: limited damage as a strategy to modulate cellular functions. Trends Microbiol. 10, 147–152 (2002)

    CAS  Article  PubMed  Google Scholar 

  12. Charles, R. C. et al. Characterization of anti-Salmonella enterica serotype Typhi antibody responses in bacteremic Bangladeshi patients by an immunoaffinity proteomics-based technology. Clin. Vaccine Immunol. (2010)

  13. Liang, L. et al. Immune profiling with a Salmonella Typhi antigen microarray identifies new diagnostic biomarkers of human typhoid. Scientific Rep. 3, 1043 (2013)

    ADS  Article  Google Scholar 

  14. Connor, B. A. & Schwartz, E. Typhoid and paratyphoid fever in travellers. Lancet Infect. Dis. 5, 623–628 (2005)

    Article  PubMed  Google Scholar 

  15. Yu, C.-Y. et al. A bipartite signal regulates the faithful delivery of apical domain marker podocalyxin/Gp135. Mol. Biol. Cell 18, 1710–1722 (2007)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  16. Hermiston, M. L., Zikherman, J. & Zhu, J. W. CD45, CD148, and Lyp/Pep: critical phosphatases regulating Src family kinase signaling networks in immune cells. Immunol. Rev. 228, 288–311 (2009)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  17. Kumar, R., Yang, J., Larsen, R. & Stanley, P. Cloning and expression of N-acetylglucosaminyltransferase I, the medial Golgi transferase that initiates complex N-linked carbohydrate formation. Proc. Natl Acad. Sci. USA 87, 9948–9952 (1990)

    ADS  CAS  Article  PubMed  PubMed Central  Google Scholar 

  18. Stanley, P., Narasimhan, S., Siminovitch, L. & Schachter, H. Chinese hamster ovary cells selected for resistance to the cytotoxicity of phytohemagglutinin are deficient in a UDP-N-acetylglucosamine–glycoprotein N-acetylglucosaminyltransferase activity. Proc. Natl Acad. Sci. USA 72, 3323–3327 (1975)

    ADS  CAS  Article  PubMed  PubMed Central  Google Scholar 

  19. Song, X. et al. Shotgun glycomics: a microarray strategy for functional glycomics. Nature Methods 8, 85–90 (2011)

    CAS  Article  PubMed  Google Scholar 

  20. Yu, R. K., Tsai, Y.-T., Ariga, T. & Yanagisawa, M. Structures, biosynthesis, and functions of gangliosides–an overview. J. Oleo Sci. 60, 537–544 (2011)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  21. Merritt, E. A. & Hol, W. G. J. AB5 toxins. Curr. Opin. Struct. Biol. 5, 165–171 (1995)

    CAS  Article  PubMed  Google Scholar 

  22. Stein, P. E. et al. The crystal structure of pertussis toxin. Structure 2, 45–57 (1994)

    CAS  Article  PubMed  Google Scholar 

  23. Nešić, D., Hsu, Y. & Stebbins, C. E. Assembly and function of a bacterial genotoxin. Nature 429, 429–433 (2004)

    ADS  Article  PubMed  Google Scholar 

  24. Locht, C., Coutte, L. & Mielcarek, N. The ins and outs of pertussis toxin. FEBS J. 278, 4668–4682 (2011)

    CAS  Article  PubMed  Google Scholar 

  25. Byres, E. et al. Incorporation of a non-human glycan mediates human susceptibility to a bacterial toxin. Nature 456, 648–652 (2008)

    ADS  CAS  Article  PubMed  PubMed Central  Google Scholar 

  26. Stein, P. E. et al. Structure of a pertussis toxin–sugar complex as a model for receptor binding. Nature Struct. Biol. 1, 591–596 (1994)

    CAS  Article  PubMed  Google Scholar 

  27. Millen, S. H., Lewallen, D. M., Herr, A. B., Iyer, S. S. & Weiss, A. A. Identification and characterization of the carbohydrate ligands recognized by pertussis toxin via a glycan microarray and surface plasmon resonance. Biochemistry 49, 5954–5967 (2010)

    CAS  Article  PubMed  Google Scholar 

  28. Saitoh, M. et al. The artAB genes encode a putative ADP-ribosyltransferase toxin homologue associated with Salmonella enterica serovar Typhimurium DT104. Microbiology 151, 3089–3096 (2005)

    CAS  Article  PubMed  Google Scholar 

  29. Galán, J. E. & Curtiss, R., III Distribution of the invA, -B, -C, and -D genes of Salmonella typhimurium among other Salmonella serovars: invA mutants of Salmonella typhi are deficient for entry into mammalian cells. Infect. Immun. 59, 2901–2908 (1991)

    PubMed  PubMed Central  Google Scholar 

  30. Kaniga, K., Bossio, J. C. & Galán, J. E. The Salmonella typhimurium invasion genes invF and invG encode homologues of the AraC and PulD family of proteins. Mol. Microbiol. 13, 555–568 (1994)

    CAS  Article  PubMed  Google Scholar 

  31. Wang, R. F. & Kushner, S. R. Construction of versatile low-copy-number vectors for cloning, sequencing and gene expression in Escherichia coli. Gene 100, 195–199 (1991)

    CAS  Article  PubMed  Google Scholar 

  32. Liu, X., Gao, B., Novik, V. & Galán, J. E. Quantitative proteomics of intracellular Campylobacter jejuni reveals metabolic reprogramming. PLoS Pathog. 8, e1002562 (2012)

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  33. Otwinowski, Z. & Minor, W. Processing of X-ray diffraction data collected in oscillation mode. Methods Enzymol. 276, 307–326 (1997)

    CAS  Article  PubMed  Google Scholar 

  34. Collaborative Computational Project, number 4. The CCP4 suite: programs for protein crystallography. Acta Crystallogr. D 50, 760–763 (1994)

  35. McCoy, A. J. et al. Phaser crystallographic software. J. Appl. Crystallogr. 40, 658–674 (2007)

    CAS  PubMed  PubMed Central  Google Scholar 

  36. Emsley, P. & Cowtan, K. Coot: model-building tools for molecular graphics. Acta Crystallogr. D 60, 2126–2132 (2004)

    Article  PubMed  Google Scholar 

  37. DeLano, W. L. S. The PyMOL Molecular Graphics System. (2002)

  38. 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 

  39. Trott, O. & Olson, A. J. AutoDock Vina: improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading. J. Comput. Chem. 31, 455–461 (2010)

    CAS  PubMed  PubMed Central  Google Scholar 

  40. Spanò, S., Liu, X. & Galán, J. E. Proteolytic targeting of Rab29 by an effector protein distinguishes the intracellular compartments of human-adapted and broad-host Salmonella. Proc. Natl Acad. Sci. USA 108, 18418–18423 (2011)

    ADS  Article  PubMed  PubMed Central  Google Scholar 

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We thank members of the Galán laboratory for careful review of this manuscript. We thank E. Folta-Stogniew for help with conducting the surface plasmon resonance and light-scattering size-exclusion chromatography assays. We also thank M. Lara-Tejero and X. Liu for mass spectrometry analysis, J. M. Kim for help with glycan array analysis software, and K.-W. Kim for help in animal inoculations. We thank W. Meng for providing help with X-ray diffraction data collection, J. Wang and C. Yan for suggestions and providing help with structure refinement, and X. Gong and M. Ke for help and suggestions with molecular docking. The glycan array analysis was carried out at the Consortium for Functional Glycomics Protein-Glycan Interaction Core, at Emory University, which is supported by PHS Grant GM098791. J.S. was supported in part by a grant from the Northeast Biodefense Center U54-AI057158 and this work was supported by NIAID Grant AI079022 to J.E.G.

Author information

Authors and Affiliations



J.S., X.G. and J.E.G. designed the studies and interpreted the results. J.S. and X.G. carried out the experiments. J.S., X.G. and J.E.G. prepared the manuscript.

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Correspondence to Jorge E. Galán.

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The authors declare no competing financial interests.

Additional information

The atomic coordinates have been deposited in the RCSB Protein Data Bank (entry number 4K6L).

Supplementary information

Supplementary Information

This file contains Supplementary Figures 1-15 and Supplementary Tables 1-4. (PDF 3846 kb)

Symptoms of animals that have received typhoid toxin or buffer control

This video shows the symptoms exhibited by animals that have received typhoid toxin or buffer control. (MOV 1900 kb)

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Song, J., Gao, X. & Galán, J. Structure and function of the Salmonella Typhi chimaeric A2B5 typhoid toxin. Nature 499, 350–354 (2013).

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