Current understanding of Bacillus anthracis toxin molecules organization and approaches for blocking their cytotoxic action

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Here, we review the data on mechanisms inhibiting cytotoxic effect of anthrax toxin on the immune system cells. Various disease forms, immunopathogenesis and contemporary methods for anthrax treatment are discussed. In addition, an anthrax toxin was outlined, whereas structural and functional organization of the protective antigen, lethal and edema factors was detailed. A mechanism for association of a protective antigen and lethal factor, protective antigen and edema factor leading to formation of a lethal toxin and edema toxin, respectively, was described. Participation of protective antigen domains in the process of interaction with surface receptors of imunocompetent cells as well as features of binding a protective antigen with lethal factor and edema factor are discussed. A mechanism of endosomal toxin complex internalization and subsequent transfer of effector molecules to the cytosol are described. Effects of the lethal factor and the edema factor on components of eukaryotic cells as well as cytotoxicity mechanisms are analyzed. The approaches to block anthrax toxin action at various stages of toxicoemia have been analyzed based on previously uncovered sequential signs of cytotoxic activity for Bacillus anthracis toxins. Currently available chimeric and humanized monoclonal antibodies are capable of neutralizing B. anthracis toxins at diverse assembly stages, particularly considering the drugs inhibiting: inter-receptor interaction between protective antigen with eukaryotic cells; furin-like enzymes activating prepore assembly; protective antigen oligomerization; binding of the lethal factor or edema factor to the protective antigen; translocation of the lethal factor or the edema factor into cell cytosol; transport of protective antigen with lethal factor or edema factor from endosomes; enzymatic activity of lethal factor or edematous factor. The anti-toxin agents approved for anthrax prevention and treatment in Russia and worldwide are discussed. The limitations of anti-toxin agents and perspectives for their improvement are also described including inhibition of lethal factor activity, interference with integration of toxin components, blockade of interactions between toxic complexes and immune cell receptors.

About the authors

V. V. Firstova

State Research Center for Applied Microbiology and Biotechnology

Author for correspondence.
ORCID iD: 0000-0002-9898-9894

Victoria V. Firstova, PhD, MD (Biology), Head Researcher of Molecular Biology

142279, Moscow Region, Obolensk.

Phone: +7 (4967) 36-00-03. Fax: +7 (4967) 36-00-10.

Russian Federation

I. G. Shemyakin

State Research Center for Applied Microbiology and Biotechnology


PhD, MD (Biology), Professor, Deputy Director for Science

Obolensk, Moscow Region

Russian Federation

I. A. Dyatlov

State Research Center for Applied Microbiology and Biotechnology


RAS Full Member, PhD, MD (Medicine), Professor, Director

Obolensk, Moscow Region

Russian Federation


  1. Abrami L., Leppla S.H., van der Goot F.G. Receptor palmitoylation and ubiquitination regulate anthrax toxin endocytosis. J. Cell Biol., 2006, vol. 172, no. 2, pp. 309–320. doi: 10.1083/jcb.200507067
  2. Albrecht M.T., Li H., Williamson E.D., LeButt C.S., Flick-Smith H.C., Quinn C.P., Westra H., Galloway D., Mateczun A., Goldman S. Human monoclonal antibodies against anthrax lethal factor and protective antigen act independently to protect against Bacillus anthracis infection and enhance endogenous immunity to anthrax. Infect. Immun., 2007, vol. 75, pp. 5425–5433.
  3. Benjamin E. Manipulation of host signalling pathways by anthrax toxins. Turk. Biochem. J., 2007, vol. 402, no. 3, pp. 405–417.
  4. Chen K.H., Liu S., Leysath C.E., Miller-Randolph S., Zhang Y., Fattah R., Bugge T.H., Leppla S.H. Anthrax toxin protective antigen variants that selectively utilize either the CMG2 or TEM8 receptors for cellular uptake and tumor targeting. J. Biol. Chem., 2016, vol. 291, no. 42, pp. 22021–22029.
  5. Chen Z., Moayeri M., Crown D., Emerson S., Gorshkova I., Schuck P., Leppla S.H., Purcell R.H. Novel chimpanzee/human monoclonal antibodies that neutralize anthrax lethal factor, and evidence for possible synergy with anti-protective antigen anti-body. Infect. Immun., 2009, vol. 77, pp. 3902–3908. doi: 10.1128/IAI.00200-09
  6. Chen Z., Moayeri M., Purcell R. Monoclonal antibody therapies against anthrax. Toxins, 2011, vol. 3, pp. 1004–1019. doi: 10.3390/toxins3081004
  7. Das D., Krantz B.A. Secondary structure preferences of the anthrax toxin protective antigen translocase. J. Mol. Biol., 2017, vol. 429, no. 5, pp. 753–762. doi: 10.1016/j.jmb.2017.01.015
  8. Deu E. Proteases as antimalarial targets: strategies for genetic, chemical, and therapeutic validation. FEBS J., 2017, vol. 284, no. 16, pp. 2604–2628. doi: 10.1111/febs.14130
  9. Dixon T.С., Meselson M., Guillemin J., Hanna P.C. Anthrax. N. Engl. J. Med., 1999, vol. 341, no. 11, pp. 815–826.
  10. Dumas E.K., Garman L., Cuthbertson H., Charlton S., Hallis B., Engler R.J.M., Choudhari S., Picking W.D., James J.A., Farris A.D. Lethal factor antibodies contribute to lethal toxin neutralization in recipients of anthrax vaccine precipitated. Vaccine, 2017, vol. 35, no. 26, pp. 3416–3422. doi: 10.1016/j.vaccine.2017.05.006
  11. Fabre L., Santelli E., Mountassif D., Donoghue A., Biswas A., Blunck R., Hanein D., Volkmann N., Liddington R., Rouiller I. Structure of anthrax lethal toxin prepore complex suggests a pathway for efficient cell entry. J. Gen. Physiol., 2016, vol. 148, no. 4, pp. 313–324. doi: 10.1085/jgp.201611617
  12. Glinert I., Bar-David E., Sittner A., Weiss S., Schlomovitz J., Ben-Shmuel A., Mechaly A., Altboum Z., Kobiler D., Levy H. Revisiting the concept of targeting only Bacillus anthracis toxins as a treatment for anthrax. Antimicrob. Agents Chemother., 2016, vol. 60, no. 8, pp. 4878–4885. doi: 10.1128/AAC.00546-16
  13. Goldberg A.B., Turk B.E. Inhibitors of the metalloproteinase anthrax lethal factor. Curr. Top. Med. Chem., 2016, vol. 16, no. 21, pp. 2350–2358.
  14. Goldstein J.M., Lee J., Tang X., Boyer A.E., Barr J.R., Bagarozzi D.A. Jr, Quinn C.P. Phage display analysis of monoclonal anti-body binding to anthrax toxin lethal factor. Toxins (Basel), 2017, vol. 9, no. 7, pp. 221. doi: 10.3390/toxins9070221
  15. Greig S.L. Obiltoxaximab: first global approval. Drugs, 2016, vol. 76, no. 7, pp. 823–830. doi: 10.1007/s40265-016-0577-0
  16. Greither T., Wedler A., Rot S., Ke ß ler J., Kehlen A., Holzhausen H.J., Bache M., Würl P., Taubert H., Kappler M. CMG2 expression is an independent prognostic factor for soft tissue sarcoma patients. Int. J. Mol. Sci., 2017, vol. 18, no. 12: E2648. doi: 10.3390/ijms18122648
  17. Hardes K., Becker G.L., Lu Y., Dahms S.O., Köhler S., Beyer W., Sandvig K., Yamamoto H., Lindberg I., Walz L., von Messling V., Than M.E., Garten W., Steinmetzer T. Novel furin inhibitors with potent anti-infectious activity. Chem. Med. Chem., 2015, vol. 10, no. 7, pp. 1218–1231. doi: 10.1002/cmdc.201500103
  18. Hu K., Olsen B.R., Besschetnova T.Y. Cell autonomous ANTXR1-mediated regulation of extracellular matrix components in primary fibroblasts. Matrix Biol., 2017, vol. 62, pp. 105–114. doi: 10.1016/j.matbio.2016
  19. Huang E., Pillai S.K., Bower W.A., Hendricks K.A., Guarnizo J.T., Hoyle J.D., Gorman S.E., Boyer A.E., Quinn C.P., Meaney-Delman D. Antitoxin treatment of inhalation anthrax: a systematic review. Health Secur., 2015, vol. 13, no. 6, pp. 365–377. doi: 10.1089/hs.2015.0032
  20. Hughes J.M., Gerberding J.L. Anthrax bioterrorism: lessons learned and future directions. Emerg. Infect. Dis., 2002, vol. 8, no. 10, pp. 1013–1014. doi: 10.3201/eid0810.020466
  21. Jeong S.Y., Martchenko M., Cohen S.N. Calpain-dependent cytoskeletal rearrangement exploited for anthrax toxin endocytosis. Proc. Natl. Acad. Sci. USA, 2013, vol. 110, no. 42: E4007–E4015. doi: 10.1073/pnas.1316852110
  22. Jia Z., Ackroyd C., Han T., Agrawal V., Liu Y., Christensen K., Dominy B. Effects from metal ion in tumor endothelial marker 8 and anthrax protective antigen: BioLayer Interferometry experiment and molecular dynamics simulation study. J. Comput. Chem., 2017, vol. 38, no. 15, pp. 1183–1190. doi: 10.1002/jcc.24768
  23. Jiang J., Pentelute B.L., Collier R.J., Zhou Z.H. Atomic structure of anthrax protective antigen pore elucidates toxin translocation. Nature, 2015, vol. 521, no 7553, pp. 545–549.
  24. Krantz B.A. Anthrax lethal toxin co-complexes are stabilized by contacts between adjacent lethal factors. J. Gen. Physiol., 2016, vol. 148, no. 4, pp. 273–275. doi: 10.1085/jgp. 201611681
  25. Kummerfeldt E.C. Raxibacumab: potential role in the treatment of inhalational anthrax. Infect. Drug Resist., 2014, pp. 101–110. doi: 10.2147/IDR.S47305
  26. Li L., Guo Q., Liu J., Zhang J., Yin Y., Dong D., Fu L., Xu J., Chen W. Recombinant HSA-CMG2 is a promising anthrax toxin inhibitor. Toxins (Basel), 2016, vol. 8, no. 1: E28. doi: 10.3390/toxins8010028
  27. Little S.F., Novak J.M., Lowe J.R., Leppla S.Н., Singh Y., Klimpel K.R., Lidgerding B.C., Friedlander A.M. Characterization of lethal factor binding and cell receptor binding domains of protective antigen of Bacillus anthracis using monoclonal antibodies. Microbiology, 1996, vol. 142, pp. 707–715.
  28. Liu C.C., Kanekiyo T., Roth B., Bu G. Tyrosine-based signal mediates LRP6 receptor endocytosis and desensitization of Wnt/ β-catenin pathway signaling. J. Biol. Chem., 2014, vol. 289, no. 40, pp. 27562–27570. doi: 10.1074/jbc.M113.533927
  29. Liu S., Zhang Y., Hoover B., Leppla S.H. The receptors that mediate the direct lethality of anthrax toxin. Toxins (Basel), 2012, vol. 5, no. 1, pp. 1–8. doi: 10.3390/toxins5010001
  30. Machen A.J., Akkaladevi N., Trecazzi C., O’Neil P.T., Mukherjee S., Qi Y., Dillard R., Im W., Gogol E.P., White T.A., Fisher M.T. Asymmetric Cryo-EM Structure of Anthrax Toxin Protective Antigen Pore with Lethal Factor N-Terminal Domain. Toxins (Basel), 2017, vol. 9, no. 10: E298. doi: 10.3390/toxins9100298
  31. Maize K.M., Kurbanov E.K., De La Mora-Rey T., Geders T.W., Hwang D.J., Walters M.A., Johnson R.L., Amin E.A., Finzel B.C. Anthrax toxin lethal factor domain 3 is highly mobile and responsive to ligand binding. Acta Crystallogr. D Biol. Crystallogr., 2014, vol. 70 (Pt. 11), pp. 2813–2822. doi: 10.1107/S1399004714018161
  32. Martchenko M., Jeong S.Y., Cohen S.N. Heterodimeric integrin complexes containing beta1-integrin promote internalization and lethality of anthrax toxin. Proc. Natl. Acad. Sci USA, 2010, vol. 107, no. 35, pp. 15583–15588. doi: 10.1073/pnas.1010145107
  33. Mechaly A., Levy H., Epstein E., Rosenfeld R., Marcus H., Ben-Arie E. A novel mechanism for antibody – based anthrax toxin neutralization: inhibition of prepore-to-pore conversion. J. Biol. Chem., 2012, vol. 287, no. 39, pp. 32665–32673. doi: 10.1074/jbc.M112.400473
  34. Mogridge J., Cunningham K., Lacy D.B., Mourez M., Collier R.J. The lethal and edema factors of anthrax toxin bind only to oligomeric forms of the protective antigen. Proc. Natl. Acad. Sci. USA, 2002, vol. 99, no. 10, pp. 7045–7048. doi: 10.1073/pnas.052160199
  35. Nestorovich E.M., Bezrukov S.M. Designing inhibitors of anthrax toxin. Expert Opin. Drug. Discov., 2014, vol. 9, no. 3, pp. 299–318. doi: 10.1517/17460441.2014.877884
  36. Petosa C., Collier R.J., Klimpel K.R., Leppla S.H., Liddington R.C. Crystal structure of the anthrax toxin protective antigen. Nature, 1997, vol. 385, no. 6619, pp. 833–838.
  37. Rawlings N.D. Bacterial calpains and the evolution of the calpain (C2) family of peptidases. Biol. Direct., 2015, vol. 10, p. 66. doi: 10.1186/s13062-015-0095-0
  38. Rubert Pérez C., L ó pez-Pérez D., Chmielewski J., Lipton M. Small molecule inhibitors of anthrax toxin-induced cytotoxicity targeted against protective antigen. Chem. Biol. Drug Des., 2012, vol. 79, no. 3, pp. 260–269. doi: 10.1111/j.1747-0285.2011.01285.x
  39. Rubinson L., Corey A., Hanfling D. Estimation of time period for effective human inhalational anthrax treatment including antitoxin therapy. PLoS Curr., 2017, vol. 9. doi: 10.1371/currents.outbreaks.7896c43f69838f17ce1c2c372e79d55d
  40. Schneemann A., Manchester M. Anti-toxin antibodies in prophylaxis and treatment of inhalation anthrax. Future Microbiol., 2009, vol. 4, pp. 35–43. doi: 10.2217/17460913.4.1.35
  41. Scobie H.M., Thomas D., Marlett J.M., Destito G., Wigelsworth D.J., Collier R.J., Young J.A., Manchester M. A soluble receptor decoy protects rats against anthrax lethal toxin challenge. J. Infect. Dis., 2005, vol. 192, no. 6, pp. 1047–1051.
  42. Thomas D., Naughton J., Cote C., Welkos S., Manchester M., Young J.A. Delayed toxicity associated with soluble anthrax toxin receptor decoy-Ig fusion protein treatment. PLoS One, 2012, vol. 7, no. 4: e34611. doi: 10.1371/journal.pone.0034611
  43. Van der Goot G., Young J.A. Receptors of anthrax toxin and cell entry. Mol. Aspects Med., 2009, vol. 30, no. 6, pp. 406–412. doi: 10.1016/j.mam.2009.08.007
  44. Zakowska D., Bartoszcze M., Niemcewicz M., Bielawska-Drózd A., Kocik J. New aspects of the infection mechanisms of Bacillus anthracis. Ann. Agric. Environ. Med., 2012, vol. 19, no. 4, pp. 613–618.

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Copyright (c) 2020 Firstova V.V., Shemyakin I.G., Dyatlov I.A.

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