Skip to main content

Thank you for visiting nature.com. 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.

  • Letter
  • Published:

Host S-nitrosylation inhibits clostridial small molecule–activated glucosylating toxins

Abstract

The global prevalence of severe Clostridium difficile infection highlights the profound clinical significance of clostridial glucosylating toxins1,2,3,4. Virulence is dependent on the autoactivation of a toxin cysteine protease5,6,7,8,9, which is promoted by the allosteric cofactor inositol hexakisphosphate (InsP6)10,11,12,13,14,15,16,17. Host mechanisms that protect against such exotoxins are poorly understood. It is increasingly appreciated that the pleiotropic functions attributed to nitric oxide (NO), including host immunity, are in large part mediated by S-nitrosylation of proteins18,19. Here we show that C. difficile toxins are S-nitrosylated by the infected host and that S-nitrosylation attenuates virulence by inhibiting toxin self-cleavage and cell entry. Notably, InsP6- and inositol pyrophosphate (InsP7)-induced conformational changes in the toxin enabled host S-nitrosothiols to transnitrosylate the toxin catalytic cysteine, which forms part of a structurally conserved nitrosylation motif. Moreover, treatment with exogenous InsP6 enhanced the therapeutic actions of oral S-nitrosothiols in mouse models of C. difficile infection. Allostery in bacterial proteins has thus been successfully exploited in the evolutionary development of nitrosothiol-based innate immunity and may provide an avenue to new therapeutic approaches.

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

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: C. difficile toxins are S-nitrosylated in vivo.
Figure 2: Toxin S-nitrosylation is allosterically regulated by inositolphosphate.
Figure 3: A catalytic-site motif for S-nitrosylation.
Figure 4: GSNO-based therapy for C. difficile infection.

Similar content being viewed by others

References

  1. Chen, X. et al. A mouse model of Clostridium difficile–associated disease. Gastroenterology 135, 1984–1992 (2008).

    Article  PubMed  Google Scholar 

  2. Savidge, T.C. et al. Clostridium difficile toxin B is an inflammatory enterotoxin in human intestine. Gastroenterology 125, 413–420 (2003).

    Article  CAS  PubMed  Google Scholar 

  3. Lyras, D. et al. Toxin B is essential for virulence of Clostridium difficile. Nature 458, 1176–1179 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  4. Kuehne, S.A. et al. The role of toxin A and toxin B in Clostridium difficile infection. Nature 467, 711–713 (2010).

    Article  CAS  PubMed  Google Scholar 

  5. Satchell, K.J. MARTX, multifunctional autoprocessing repeats-in-toxin toxins. Infect. Immun. 75, 5079–5084 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Sheahan, K.L., Cordero, C.L. & Fullner Satchell, K.J. Autoprocessing of the Vibrio cholerae RTX toxin by the cysteine protease domain. EMBO J. 26, 2552–2561 (2007).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  7. Egerer, M. et al. Auto-catalytic cleavage of Clostridium difficile toxins A and B depends on cysteine protease activity. J. Biol. Chem. 282, 25314–25321 (2007).

    Article  CAS  PubMed  Google Scholar 

  8. Pei, J., Lupardus, P.J., Garcia, K.C. & Grishin, N.V. CPDadh: a new peptidase family homologous to the cysteine protease domain in bacterial MARTX toxins. Protein Sci. 18, 856–862 (2009).

    CAS  PubMed  PubMed Central  Google Scholar 

  9. Puri, A.W. et al. Rational design of inhibitors and activity-based probes targeting Clostridium difficile virulence factor TcdB. Chem. Biol. 17, 1201–1211 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Reineke, J. et al. Autocatalytic cleavage of Clostridium difficile toxin B. Nature 446, 415–419 (2007).

    Article  CAS  PubMed  Google Scholar 

  11. Prochazkova, K. & Fullner Satchell, K.J. Structure-function analysis of inositol hexakisphosphate-induced autoprocessing of the Vibrio cholerae multifunctional autoprocessing RTX toxin. J. Biol. Chem. 283, 23656–23664 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Lupardus, P.J., Shen, A., Bogyo, M. & Garcia, K.C. Small molecule–induced allosteric activation of the Vibrio cholera RTX cysteine protease domain. Science 322, 265–268 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Egerer, M., Giesemann, T., Herrmann, C. & Aktories, K. Auto-catalytic processing of Clostridium difficile toxin B-binding of inositol hexakisphosphate. J. Biol. Chem. 284, 3389–3395 (2009).

    Article  CAS  PubMed  Google Scholar 

  14. Prochazkova, K. et al. Structural and molecular mechanism for autoprocessing of MARTX toxin of Vibrio cholera at multiple sites. J. Biol. Chem. 284, 26557–26568 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  15. Pruitt, R.N., Chagot, B., Cover, M., Chazin, W.J. & Lacy, D.B. Structure-function analysis of inositol hexakisphosphate-induced autoprocessing in Clostridium difficile toxin A. J. Biol. Chem. 284, 21934–21940 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  16. Kreimeyer, I. et al. Autoproteolytic cleavage mediates cytotoxicity of Clostridium difficile toxin A. Naunyn Schmiedebergs Arch. Pharmacol. 383, 253–262 (2011).

    Article  CAS  PubMed  Google Scholar 

  17. Guttenberg, G. et al. Clostridal glucosylating toxins: inositol hexakisphosphate-dependent processing of Closterium sordellii lethal toxin and Clostridium novyi α-toxin. J. Biol. Chem. 286, 14779–14786 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Benhar, M., Forrester, M.T. & Stamler, J.S. Protein denitrosylation: enzymatic mechanisms and cellular functions. Nat. Rev. Mol. Cell Biol. 10, 721–732 (2009).

    Article  CAS  PubMed  Google Scholar 

  19. Foster, M.W., Hess, D.T. & Stamler, J.S. S-nitrosylation in health and disease-a current perspective. Trends Mol. Med. 15, 391–404 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Qiu, B., Pothoulakis, C., Castagliuolo, I., Nikulasson, Z. & LaMont, J.T. Nitric oxide inhibits rat intestinal secretion by Clostridium difficile toxin A but not Vibrio cholerae enterotoxin. Gastroenterology 111, 409–418 (1996).

    Article  CAS  PubMed  Google Scholar 

  21. Ng, J. et al. Clostridium difficile toxin–induced inflammation and intestinal injury are mediated by the inflammasome. Gastroenterology 139, 542–552 (2010).

    Article  CAS  PubMed  Google Scholar 

  22. Que, L.G. et al. Protection from experimental asthma by an endogenous bronchodilator. Science 308, 1618–1621 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  23. Savidge, T.C. et al. Enteric glia regulate intestinal barrier function and inflammation via release of S-nitrosoglutathione. Gastroenterology 132, 1344–1358 (2007).

    Article  CAS  PubMed  Google Scholar 

  24. Hausladen, A. et al. Assessment of nitric oxide signals by triodide chemiluminescence. Proc. Natl. Acad. Sci. USA 104, 2157–2162 (2007).

    Article  CAS  PubMed  Google Scholar 

  25. Wiktorowicz, J. et al. Quantification of cysteinyl S-nitrosylation by fluorescence in unbiased proteomic studies. Biochemistry 50, 5601–5614 (2011).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  26. Jaffrey, S.R. & Snyder, S.H. The biotin-switch method for the detection of S-nitrosylated proteins. Sci. STKE 2001, pl1 (2001).

    CAS  PubMed  Google Scholar 

  27. Gow, A.J. et al. Basal and stimulated protein S-nitrosylation in multiple cell types and tissues. J. Biol. Chem. 277, 9637–9640 (2002).

    Article  CAS  PubMed  Google Scholar 

  28. Popoff, M.R. & Geny, B. Multifaceted role of Rho, Rac, Cdc42 and Ras in intercellular junctions, lessons from toxins. Biochim. Biophys. Acta 88, 797–812 (2009).

    Article  Google Scholar 

  29. Kim, S.F., Huri, D.A. & Snyder, S.H. Inducible nitric oxide synthase binds, S-nitrosylates, and activates cyclooxygenase-2. Science 310, 1966–1970 (2005).

    Article  CAS  PubMed  Google Scholar 

  30. He, X. et al. An ultrasensitive rapid immunocytotoxicity assay for detecting Clostridium difficile toxins. J. Microbiol. Methods 78, 97–100 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  31. Marino, S.M. & Gladyshev, V.N. Structural analysis of cysteine S-nitrosylation: a modified acid-based motif and the emerging role of trans-nitrosylation. J. Mol. Biol. 395, 844–859 (2010).

    Article  CAS  PubMed  Google Scholar 

  32. Eichinger, A. et al. Crystal structure of gingipain R: an Arg-specific bacterial cysteine proteinase with a caspase-like fold. EMBO J. 18, 5453–5462 (1999).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  33. Chakraborty, A. et al. Inositol pyrophosphates inhibit Akt signaling, thereby regulating insulin sensitivity and weight gain. Cell 143, 897–910 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Tang, H.Y. & Speicher, D.W. Identification of alternative products and optimization of 2-nitro-5-thiocyanatobenzoic acid cyanylation and cleavage at cysteine residues. Anal. Biochem. 334, 48–61 (2004).

    Article  CAS  PubMed  Google Scholar 

  35. McMahon, T.J. et al. Functional coupling of oxygen binding and vasoactivity in S-nitrosohemoglobin. J. Biol. Chem. 275, 16738–16745 (2000).

    Article  CAS  PubMed  Google Scholar 

  36. Matsumoto, A., Comatas, K.E., Liu, L. & Stamler, J.S. Screening for nitric oxide–dependent protein-protein interactions. Science 301, 657–661 (2003).

    Article  CAS  PubMed  Google Scholar 

  37. Benhar, M., Forrester, M.T., Hess, D.T. & Stamler, J.S. Regulated protein denitrosylation by cytosolic and mitochondrial thioredoxins. Science 320, 1050–1054 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  38. Cui, Q. & Karplus, M. Allostery and cooperativity revisited. Protein Sci. 17, 1295–1307 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  39. Saura, M. et al. An antiviral mechanism of nitric oxide: Inhibition of a viral protease. Immunity 10, 21–28 (1999).

    Article  CAS  PubMed  Google Scholar 

  40. Eu, J.P., Sun, J., Xu, L., Stamler, J.S. & Meissner, G. The skeletal muscle calcium release channel: coupled O2 sensor and NO signaling functions. Cell 102, 499–509 (2000).

    Article  CAS  PubMed  Google Scholar 

Download references

Acknowledgements

This work was supported by the Eli & Edith Broad Foundation, the John S. Dunn Gulf Coast Consortium for Chemical Genomics Robert A. Welch Collaborative Grant Program, the Howard Hughes Medical Institute and grants from the US National Institutes of Health National Institute of Allergy and Infectious Diseases (R01AI088748, N01AI30050), National Institute of Diabetes and Digestive and Kidney Diseases (R01DK084509, K01DK076549; R21-DK078032-01), National Heart, Lung, and Blood Institute (R01-HL059130, R01-HL091876, R01-HL095463, P01-HL075443-06A, NO1-HV-00245) and 1UL1RR029876-01. We thank D. Powell, S. Weinman, C.S. Schein and G. Prestwich for their critiques.

Author information

Authors and Affiliations

Authors

Contributions

T.C.S. designed the study, performed InsP6, GSNO and cytotoxicity assays, BIACORE analysis, and wrote the paper; P.U. performed the toxin S-nitrosylation and InsP6 binding studies; N.O. and W.B. performed the toxin structural modeling and molecular docking simulations; I.P. performed the SNO immunofluorescence; K.A., A.C. and V.A. performed toxin autocleavage, InsP7 phosphorylation and UDP-glucosylation assays; A.G.T. performed animal toxin studies; R.D.E. performed the mass spectrometry; J.E.W. performed the cysteine saturation labeling studies; M.L. provided clinical specimens; R.K. performed the CD spectral analysis; L.S., W.N. and H.F. developed the toxin mutants, performed InsP6 cleavage and stool cytotoxicity assays and animals studies; B.H., A.H. and J.S.S. performed or oversaw the measurements of GSNO and SNO proteins; J.S.S. assisted with the study design and writing of the paper; C.P. prepared holotoxins, performed animal toxin studies and assisted with study design and manuscript editing.

Corresponding author

Correspondence to Tor C Savidge.

Ethics declarations

Competing interests

C.P. is a paid consultant with Merck and Optimer Pharmaceuticals and a paid speaker for the Postgraduate Institute for Medicine. J.S.S. has a small financial interest in N30 Pharma, Adamas Pharma, Vindica LLC, SabrePharm and LifeHealth, early-stage companies in development of nitric oxide–related therapeutics.

Supplementary information

Supplementary Text and Figures

Supplementary Figures 1–15 and Supplementary Methods (PDF 1811 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Savidge, T., Urvil, P., Oezguen, N. et al. Host S-nitrosylation inhibits clostridial small molecule–activated glucosylating toxins. Nat Med 17, 1136–1141 (2011). https://doi.org/10.1038/nm.2405

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nm.2405

This article is cited by

Search

Quick links

Nature Briefing Microbiology

Sign up for the Nature Briefing: Microbiology newsletter — what matters in microbiology research, free to your inbox weekly.

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