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Zhou Y, Zhan X, Luo J, Li D, Zhou R, Zhang J, Pan Z, Zhang Y, Jia T, Zhang X, Li Y, Tao L. Structural dynamics of the CROPs domain control stability and toxicity of Paeniclostridium sordellii lethal toxin. Nat Commun 2023; 14:8426. [PMID: 38114525 PMCID: PMC10730571 DOI: 10.1038/s41467-023-44169-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 12/04/2023] [Indexed: 12/21/2023] Open
Abstract
Paeniclostridium sordellii lethal toxin (TcsL) is a potent exotoxin that causes lethal toxic shock syndrome associated with fulminant bacterial infections. TcsL belongs to the large clostridial toxin (LCT) family. Here, we report that TcsL with varied lengths of combined repetitive oligopeptides (CROPs) deleted show increased autoproteolysis as well as higher cytotoxicity. We next present cryo-EM structures of full-length TcsL, at neutral (pH 7.4) and acidic (pH 5.0) conditions. The TcsL at neutral pH exhibits in the open conformation, which resembles reported TcdB structures. Low pH induces the conformational change of partial TcsL to the closed form. Two intracellular interfaces are observed in the closed conformation, which possibly locks the cysteine protease domain and hinders the binding of the host receptor. Our findings provide insights into the structure and function of TcsL and reveal mechanisms for CROPs-mediated modulation of autoproteolysis and cytotoxicity, which could be common across the LCT family.
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Affiliation(s)
- Yao Zhou
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
- Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, 310024, China
| | - Xiechao Zhan
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China.
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China.
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China.
| | - Jianhua Luo
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
- Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, 310024, China
| | - Diyin Li
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
- Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, 310024, China
| | - Ruoyu Zhou
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
| | - Jiahao Zhang
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
| | - Zhenrui Pan
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
| | - Yuanyuan Zhang
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
| | - Tianhui Jia
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
- Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, 310024, China
| | - Xiaofeng Zhang
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
| | - Yanyan Li
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China
| | - Liang Tao
- Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, 310024, China.
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China.
- Westlake Institute for Advanced Study, Hangzhou, Zhejiang, 310024, China.
- Research Center for Industries of the Future, Westlake University, Hangzhou, Zhejiang, 310024, China.
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2
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Sinnathamby ES, Mason JW, Flanagan CJ, Pearl NZ, Burroughs CR, De Witt AJ, Wenger DM, Klapper VG, Ahmadzadeh S, Varrassi G, Shekoohi S, Kaye AD. Clostridioides difficile Infection: A Clinical Review of Pathogenesis, Clinical Considerations, and Treatment Strategies. Cureus 2023; 15:e51167. [PMID: 38283489 PMCID: PMC10811429 DOI: 10.7759/cureus.51167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 12/27/2023] [Indexed: 01/30/2024] Open
Abstract
BACKGROUND Clostridioides difficile infection (CDI) is a common nosocomial infection. Risk factors for developing CDI include prior hospitalization, being older than 65 years old, antibiotic use, and chronic disease. It is linked with diarrhea and colitis and can vary in severity. It is a major cause of increased morbidity and mortality among hospitalized patients. However, community-acquired CDI is also increasing. Proper diagnosis and determination of severity are crucial for the treatment of CDI. Depending on how severe the CDI is, the patient may endorse different symptoms and physical exam findings. The severity of CDI will determine how aggressively it is treated. Management and treatment: Laboratory studies can be helpful in the diagnosis of CDI. In this regard, common labs include complete blood count, stool assays, and, in certain cases, radiography and endoscopy. Mild-to-moderate colitis is treated with antibiotics, but severe colitis requires a different approach, which may include surgery. Several alternative therapies for CDI exist and have shown promising results. This review will touch upon these therapies, which include fecal transplants, intravenous immunoglobulin, and the use of cholestyramine and tigecycline. CONCLUSION Prevention of CDI can be achieved by proper hygiene, vaccinations, and detecting the infection early. Proper hygiene is indeed noted to be one of the best ways to prevent CDI in the hospital setting. Overprescribing antibiotics is also another huge reason why CDI occurs. Proper prescription of antibiotics can also help reduce the chances of acquiring CDI.
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Affiliation(s)
- Evan S Sinnathamby
- School of Medicine, Louisiana State University Health Sciences Center (LSUHSC) New Orleans, New Orleans, USA
| | - Joseph W Mason
- School of Medicine, Louisiana State University Health Sciences Center (LSUHSC) New Orleans, New Orleans, USA
| | - Chelsi J Flanagan
- School of Medicine, University of the Incarnate Word School of Osteopathic Medicine, San Antonio, USA
| | - Nathan Z Pearl
- School of Medicine, Louisiana State University Health Sciences Center (LSUHSC) New Orleans, New Orleans, USA
| | - Caroline R Burroughs
- School of Medicine, Louisiana State University Health Shreveport, Shreveport, USA
| | - Audrey J De Witt
- School of Medicine, Louisiana State University Health Shreveport, Shreveport, USA
| | - Danielle M Wenger
- Department of Medicine, University of Arizona College of Medicine - Phoenix, Phoenix, USA
| | - Vincent G Klapper
- Department of Internal Medicine, Louisiana State University Health Shreveport, Shreveport, USA
| | - Shahab Ahmadzadeh
- Department of Anesthesiology, Louisiana State University Health Shreveport, Shreveport, USA
| | | | - Sahar Shekoohi
- Department of Anesthesiology, Louisiana State University Health Shreveport, Shreveport, USA
| | - Alan D Kaye
- Department of Anesthesiology, Louisiana State University Health Shreveport, Shreveport, USA
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3
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Cheng JKJ, Unnikrishnan M. Clostridioides difficile infection: traversing host-pathogen interactions in the gut. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36848200 DOI: 10.1099/mic.0.001306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
C. difficile is the primary cause for nosocomial infective diarrhoea. For a successful infection, C. difficile must navigate between resident gut bacteria and the harsh host environment. The perturbation of the intestinal microbiota by broad-spectrum antibiotics alters the composition and the geography of the gut microbiota, deterring colonization resistance, and enabling C. difficile to colonize. This review will discuss how C. difficile interacts with and exploits the microbiota and the host epithelium to infect and persist. We provide an overview of C. difficile virulence factors and their interactions with the gut to aid adhesion, cause epithelial damage and mediate persistence. Finally, we document the host responses to C. difficile, describing the immune cells and host pathways that are associated and triggered during C. difficile infection.
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Affiliation(s)
- Jeffrey K J Cheng
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | - Meera Unnikrishnan
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
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4
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Kordus SL, Thomas AK, Lacy DB. Clostridioides difficile toxins: mechanisms of action and antitoxin therapeutics. Nat Rev Microbiol 2022; 20:285-298. [PMID: 34837014 PMCID: PMC9018519 DOI: 10.1038/s41579-021-00660-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 01/03/2023]
Abstract
Clostridioides difficile is a Gram-positive anaerobe that can cause a spectrum of disorders that range in severity from mild diarrhoea to fulminant colitis and/or death. The bacterium produces up to three toxins, which are considered the major virulence factors in C. difficile infection. These toxins promote inflammation, tissue damage and diarrhoea. In this Review, we highlight recent biochemical and structural advances in our understanding of the mechanisms that govern host-toxin interactions. Understanding how C. difficile toxins affect the host forms a foundation for developing novel strategies for treatment and prevention of C. difficile infection.
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Affiliation(s)
- Shannon L. Kordus
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - Audrey K. Thomas
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,These authors contributed equally: Shannon L. Kordus, Audrey K. Thomas
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA,Center for Structural Biology, Vanderbilt University, Nashville, TN, USA,The Veterans Affairs, Tennessee Valley Healthcare, System, Nashville, TN, USA,
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5
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Chen B, Basak S, Chen P, Zhang C, Perry K, Tian S, Yu C, Dong M, Huang L, Bowen ME, Jin R. Structure and conformational dynamics of Clostridioides difficile toxin A. Life Sci Alliance 2022; 5:5/6/e202201383. [PMID: 35292538 PMCID: PMC8924006 DOI: 10.26508/lsa.202201383] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/25/2022] [Accepted: 02/28/2022] [Indexed: 01/05/2023] Open
Abstract
This study presents a complete structural model of TcdA holotoxin and sheds new lights into the conformational dynamics of TcdA and its roles in TcdA intoxication. Clostridioides difficile toxin A and B (TcdA and TcdB) are two major virulence factors responsible for diseases associated with C. difficile infection (CDI). Here, we report the 3.18-Å resolution crystal structure of a TcdA fragment (residues L843–T2481), which advances our understanding of the complete structure of TcdA holotoxin. Our structural analysis, together with complementary single molecule FRET and limited proteolysis studies, reveal that TcdA adopts a dynamic structure and its CROPs domain can sample a spectrum of open and closed conformations in a pH-dependent manner. Furthermore, a small globular subdomain (SGS) and the CROPs protect the pore-forming region of TcdA in the closed state at neutral pH, which could contribute to modulating the pH-dependent pore formation of TcdA. A rationally designed TcdA mutation that trapped the CROPs in the closed conformation showed drastically reduced cytotoxicity. Taken together, these studies shed new lights into the conformational dynamics of TcdA and its roles in TcdA intoxication.
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Affiliation(s)
- Baohua Chen
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Sujit Basak
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Peng Chen
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Changcheng Zhang
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL, USA
| | - Songhai Tian
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Min Dong
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, MA, USA
| | - Lan Huang
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Mark E Bowen
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Rongsheng Jin
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, USA
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6
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Abstract
Large clostridial toxins (LCTs) are a family of bacterial exotoxins that infiltrate and destroy target cells. Members of the LCT family include Clostridioides difficile toxins TcdA and TcdB, Paeniclostridium sordellii toxins TcsL and TcsH, Clostridium novyi toxin TcnA, and Clostridium perfringens toxin TpeL. Since the 19th century, LCT-secreting bacteria have been isolated from the blood, organs, and wounds of diseased individuals, and LCTs have been implicated as the primary virulence factors in a variety of infections, including C. difficile infection and some cases of wound-associated gas gangrene. Clostridia express and secrete LCTs in response to various physiological signals. LCTs invade host cells by binding specific cell surface receptors, ultimately leading to internalization into acidified vesicles. Acidic pH promotes conformational changes within LCTs, which culminates in translocation of the N-terminal glycosyltransferase and cysteine protease domain across the endosomal membrane and into the cytosol, leading first to cytopathic effects and later to cytotoxic effects. The focus of this review is on the role of LCTs in infection and disease, the mechanism of LCT intoxication, with emphasis on recent structural work and toxin subtyping analysis, and the genomic discovery and characterization of LCT homologues. We provide a comprehensive review of these topics and offer our perspective on emerging questions and future research directions for this enigmatic family of toxins.
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7
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Henkel D, Tatge H, Schöttelndreier D, Tao L, Dong M, Gerhard R. Receptor Binding Domains of TcdB from Clostridioides difficile for Chondroitin Sulfate Proteoglycan-4 and Frizzled Proteins Are Functionally Independent and Additive. Toxins (Basel) 2020; 12:toxins12120736. [PMID: 33255261 PMCID: PMC7759879 DOI: 10.3390/toxins12120736] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 02/06/2023] Open
Abstract
Toxin B (TcdB) produced by Clostridioides difficile is a main pathogenicity factor that affects a variety of different cell types within the colonic mucosa. TcdB is known to utilize frizzled-1,2,7 and chondroitin sulfate proteoglycan-4 (CSPG4) as protein receptors. By using human cervical cancer cell line HeLa CSPG4 knockout (CSPG4−/−) cells as well as TcdB mutants which do not bind to either CSPG4 or frizzled-1,2,7, or both, we evaluated the impact of the individual receptors for cytopathic and cytotoxic effects of TcdB. We compared TcdB from the reference strain VPI10463 (TcdBVPI) and the endemic strain R20291 (TcdBR20) which does not interact with frizzled-1,2,7. TcdBVPI devoid of CSPG4 binding (TcdBVPI ΔCROP) shows identical cytopathic potency as full-length TcdB in HeLa CSPG4−/− cells, indicating that interaction with frizzled proteins is not affected in the presence of the C-terminal CROP domain. We validated CSPG4 as cellular receptor for both TcdB toxinotypes in HeLa and HEp-2 cells. By exchange of a single phenylalanine residue, 1597 with serine, we generated a mutated TcdBVPI variant (TcdBVPI F1597S) that in accordance with TcdBR20 lacks binding to frizzled-1,2,7 and showed identical potency as TcdBR20 on HeLa cells. This enabled us to estimate the respective share of CSPG4 and frizzled-1,2,7 in the cytotoxic and cytopathic effect induced by TcdB. Our data reveal that binding to frizzled-1,2,7 and to CSPG4 occurs independently and in an additive manner.
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Affiliation(s)
- Daniel Henkel
- Institute of Toxicology, Hannover Medical School, 30625 Hannover, Germany; (D.H.); (H.T.); (D.S.)
| | - Helma Tatge
- Institute of Toxicology, Hannover Medical School, 30625 Hannover, Germany; (D.H.); (H.T.); (D.S.)
| | - Dennis Schöttelndreier
- Institute of Toxicology, Hannover Medical School, 30625 Hannover, Germany; (D.H.); (H.T.); (D.S.)
| | - Liang Tao
- Department of Urology, Boston Children’s Hospital, Boston, MA 02115, USA; (L.T.); (M.D.)
- Departments of Surgery and Microbiology, Harvard Medical School, Boston, MA 02115, USA
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Westlake University Hangzhou, Hangzhou 310000, China
| | - Min Dong
- Department of Urology, Boston Children’s Hospital, Boston, MA 02115, USA; (L.T.); (M.D.)
- Departments of Surgery and Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Ralf Gerhard
- Institute of Toxicology, Hannover Medical School, 30625 Hannover, Germany; (D.H.); (H.T.); (D.S.)
- Correspondence:
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8
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di Masi A, Leboffe L, Polticelli F, Tonon F, Zennaro C, Caterino M, Stano P, Fischer S, Hägele M, Müller M, Kleger A, Papatheodorou P, Nocca G, Arcovito A, Gori A, Ruoppolo M, Barth H, Petrosillo N, Ascenzi P, Di Bella S. Human Serum Albumin Is an Essential Component of the Host Defense Mechanism Against Clostridium difficile Intoxication. J Infect Dis 2019; 218:1424-1435. [PMID: 29868851 DOI: 10.1093/infdis/jiy338] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 06/01/2018] [Indexed: 01/05/2023] Open
Abstract
Background The pathogenic effects of Clostridium difficile are primarily attributable to the production of the large protein toxins (C difficile toxins [Tcd]) A (TcdA) and B (TcdB). These toxins monoglucosylate Rho GTPases in the cytosol of host cells, causing destruction of the actin cytoskeleton with cytotoxic effects. Low human serum albumin (HSA) levels indicate a higher risk of acquiring and developing a severe C difficile infection (CDI) and are associated with recurrent and fatal disease. Methods We used a combined approach based on docking simulation and biochemical analyses that were performed in vitro on purified proteins and in human epithelial colorectal adenocarcinoma cells (Caco-2), and in vivo on stem cell-derived human intestinal organoids and zebrafish embryos. Results Our results show that HSA specifically binds via its domain II to TcdA and TcdB and thereby induces their autoproteolytic cleavage at physiological concentrations. This process impairs toxin internalization into the host cells and reduces the toxin-dependent glucosylation of Rho proteins. Conclusions Our data provide evidence for a specific HSA-dependent self-defense mechanism against C difficile toxins and provide an explanation for the clinical correlation between CDI severity and hypoalbuminemia.
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Affiliation(s)
| | - Loris Leboffe
- Department of Sciences, Roma Tre University, Roma, Italy
| | - Fabio Polticelli
- Department of Sciences, Roma Tre University, Roma, Italy.,National Institute of Nuclear Physics, Roma Tre Section, Roma, Italy
| | - Federica Tonon
- Department of Medical, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Cristina Zennaro
- Department of Medical, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Marianna Caterino
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli "Federico II", Napoli, Italy.,Associazione Culturale DiSciMuS RCF, Casoria, Napoli, Italy
| | - Pasquale Stano
- Department of Sciences, Roma Tre University, Roma, Italy
| | - Stephan Fischer
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Marlen Hägele
- Department of Internal Medicine I, University of Ulm Medical Center, Germany
| | - Martin Müller
- Department of Internal Medicine I, University of Ulm Medical Center, Germany
| | - Alexander Kleger
- Department of Internal Medicine I, University of Ulm Medical Center, Germany
| | - Panagiotis Papatheodorou
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Giuseppina Nocca
- Institute of Biochemistry and Clinical Biochemistry, Catholic University of Sacred Heart, Roma, Italy.,Institute of Chemistry of Molecular Recognition, CNR, Roma, Italy
| | - Alessandro Arcovito
- Institute of Biochemistry and Clinical Biochemistry, Catholic University of Sacred Heart, Roma, Italy
| | - Andrea Gori
- Clinic of Infectious Diseases, San Gerardo Hospital, University of Milano-Bicocca, Monza, Italy
| | - Margherita Ruoppolo
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli "Federico II", Napoli, Italy.,Associazione Culturale DiSciMuS RCF, Casoria, Napoli, Italy.,CEINGE Biotecnologie Avanzate, Napoli, Italy
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Nicola Petrosillo
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Roma, Italy
| | - Paolo Ascenzi
- Department of Sciences, Roma Tre University, Roma, Italy
| | - Stefano Di Bella
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Roma, Italy
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9
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Chen P, Lam KH, Liu Z, Mindlin FA, Chen B, Gutierrez CB, Huang L, Zhang Y, Hamza T, Feng H, Matsui T, Bowen ME, Perry K, Jin R. Structure of the full-length Clostridium difficile toxin B. Nat Struct Mol Biol 2019; 26:712-719. [PMID: 31308519 PMCID: PMC6684407 DOI: 10.1038/s41594-019-0268-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 06/07/2019] [Indexed: 01/07/2023]
Abstract
Clostridium difficile is an opportunistic pathogen that establishes in the colon when the gut microbiota are disrupted by antibiotics or disease. C. difficile infection (CDI) is largely caused by two virulence factors, TcdA and TcdB. Here, we report a 3.87-Å-resolution crystal structure of TcdB holotoxin that captures a unique conformation of TcdB at endosomal pH. Complementary biophysical studies suggest that the C-terminal combined repetitive oligopeptides (CROPs) domain of TcdB is dynamic and can sample open and closed conformations that may facilitate modulation of TcdB activity in response to environmental and cellular cues during intoxication. Furthermore, we report three crystal structures of TcdB-antibody complexes that reveal how antibodies could specifically inhibit the activities of individual TcdB domains. Our studies provide novel insight into the structure and function of TcdB holotoxin and identify intrinsic vulnerabilities that could be exploited to develop new therapeutics and vaccines for the treatment of CDI.
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Affiliation(s)
- Peng Chen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Kwok-Ho Lam
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Zheng Liu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Frank A Mindlin
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Baohua Chen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Craig B Gutierrez
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Yongrong Zhang
- Department of Microbial Pathogenesis, University of Maryland Baltimore, Baltimore, MD, USA
| | - Therwa Hamza
- Department of Microbial Pathogenesis, University of Maryland Baltimore, Baltimore, MD, USA
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Baltimore, Baltimore, MD, USA
| | - Tsutomu Matsui
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA
| | - Mark E Bowen
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL, USA
| | - Rongsheng Jin
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA.
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10
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Deletion of a 19-Amino-Acid Region in Clostridioides difficile TcdB2 Results in Spontaneous Autoprocessing and Reduced Cell Binding and Provides a Nontoxic Immunogen for Vaccination. Infect Immun 2019; 87:IAI.00210-19. [PMID: 31138612 DOI: 10.1128/iai.00210-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/17/2019] [Indexed: 11/20/2022] Open
Abstract
Clostridioides difficile toxin B (TcdB) is an intracellular toxin responsible for many of the pathologies of C. difficile infection. The two variant forms of TcdB (TcdB1 and TcdB2) share 92% sequence identity but have reported differences in rates of cell entry, autoprocessing, and overall toxicity. This 2,366-amino-acid, multidomain bacterial toxin glucosylates and inactivates small GTPases in the cytosol of target cells, ultimately leading to cell death. Successful cell entry and intoxication by TcdB are known to involve various conformational changes in the protein, including a proteolytic autoprocessing event. Previous studies found that amino acids 1753 to 1852 influence the conformational states of the proximal carboxy-terminal domain of TcdB and could contribute to differences between TcdB1 and TcdB2. In the current study, a combination of approaches was used to identify sequences within the region from amino acids 1753 to 1852 that influence the conformational integrity and cytotoxicity of TcdB2. Four deletion mutants with reduced cytotoxicity were identified, while one mutant, TcdB2Δ1769-1787, exhibited no detectable cytotoxicity. TcdB2Δ1769-1787 underwent spontaneous autoprocessing and was unable to interact with CHO-K1 or HeLa cells, suggesting a potential change in the conformation of the mutant protein. Despite the putative alteration in structural stability, vaccination with TcdB2Δ1769-1787 induced a TcdB2-neutralizing antibody response and protected against C. difficile disease in a mouse model. These findings indicate that the 19-amino-acid region spanning residues 1769 to 1787 in TcdB2 is crucial to cytotoxicity and the structural regulation of autoprocessing and that TcdB2Δ1769-1787 is a promising candidate for vaccination.
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Fühner V, Heine PA, Helmsing S, Goy S, Heidepriem J, Loeffler FF, Dübel S, Gerhard R, Hust M. Development of Neutralizing and Non-neutralizing Antibodies Targeting Known and Novel Epitopes of TcdB of Clostridioides difficile. Front Microbiol 2018; 9:2908. [PMID: 30574127 PMCID: PMC6291526 DOI: 10.3389/fmicb.2018.02908] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 11/13/2018] [Indexed: 12/18/2022] Open
Abstract
Clostridioides difficile is the causative bacterium in 15-20% of all antibiotic associated diarrheas. The symptoms associated with C. difficile infection (CDI) are primarily induced by the two large exotoxins TcdA and TcdB. Both toxins enter target cells by receptor-mediated endocytosis. Although different toxin receptors have been identified, it is no valid therapeutic option to prevent receptor endocytosis. Therapeutics, such as neutralizing antibodies, directly targeting both toxins are in development. Interestingly, only the anti-TcdB antibody bezlotoxumab but not the anti-TcdA antibody actoxumab prevented recurrence of CDI in clinical trials. In this work, 31 human antibody fragments against TcdB were selected by antibody phage display from the human naive antibody gene libraries HAL9/10. These antibody fragments were further characterized by in vitro neutralization assays. The epitopes of the neutralizing and non-neutralizing antibody fragments were analyzed by domain mapping, TcdB fragment phage display, and peptide arrays, to identify neutralizing and non-neutralizing epitopes. A new neutralizing epitope within the glucosyltransferase domain of TcdB was identified, providing new insights into the relevance of different toxin regions in respect of neutralization and toxicity.
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Affiliation(s)
- Viola Fühner
- Department Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Philip Alexander Heine
- Department Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Saskia Helmsing
- Department Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Sebastian Goy
- Institute for Toxicology, Hannover Medical School, Hannover, Germany
| | - Jasmin Heidepriem
- Department Synthetic Array Technologies, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Felix F. Loeffler
- Department Synthetic Array Technologies, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Stefan Dübel
- Department Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Ralf Gerhard
- Institute for Toxicology, Hannover Medical School, Hannover, Germany
| | - Michael Hust
- Department Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
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Chung SY, Schöttelndreier D, Tatge H, Fühner V, Hust M, Beer LA, Gerhard R. The Conserved Cys-2232 in Clostridioides difficile Toxin B Modulates Receptor Binding. Front Microbiol 2018; 9:2314. [PMID: 30416488 PMCID: PMC6212469 DOI: 10.3389/fmicb.2018.02314] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/11/2018] [Indexed: 12/14/2022] Open
Abstract
Clostridioides difficile toxins TcdA and TcdB are large clostridial glucosyltransferases which are the main pathogenicity factors in C. difficile-associated diseases. Four highly conserved cysteines are present in all large clostridial glucosyltransferases. In this study we focused on the conserved cysteine 2232 within the combined repetitive oligopeptide domain of TcdB from reference strain VPI10463 (clade I). Cysteine 2232 is not present in TcdB from hypervirulent strain R20291 (clade II), where a tyrosine is found instead. Replacement of cysteine 2232 by tyrosine in TcdBV PI10463 reduced binding to the soluble fragments of the two known TcdB receptors, frizzled-2 (FZD2) and poliovirus receptor-like protein-3/nectin-3 (PVRL3). In line with this, TcdBR20291 showed weak binding to PVRL3 in pull-down assays which was increased when tyrosine 2232 was exchanged for cysteine. Surprisingly, we did not observe binding of TcdBR20291 to FZD2, indicating that this receptor is less important for this toxinotype. Competition assay with the receptor binding fragments (aa 1101–1836) of TcdBV PI10463 and TcdBR20291, as well as antibodies newly developed by antibody phage display, revealed different characteristics of the yet poorly described delivery domain of TcdB harboring the second receptor binding region. In summary, we found that conserved Cys-2232 in TcdB indirectly contributes to toxin–receptor interaction.
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Affiliation(s)
- Soo-Young Chung
- Institute of Toxicology, Hannover Medical School, Hanover, Germany
| | | | - Helma Tatge
- Institute of Toxicology, Hannover Medical School, Hanover, Germany
| | - Viola Fühner
- Department of Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Michael Hust
- Department of Biotechnology, Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
| | | | - Ralf Gerhard
- Institute of Toxicology, Hannover Medical School, Hanover, Germany
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Puri BK, Derham A, Monro JA. Prevention of Infection in Adults Receiving Intravenous Antibiotic Treatment via Indwelling Central Venous Access Devices. Rev Recent Clin Trials 2018; 14:47-49. [PMID: 30117400 DOI: 10.2174/1574887113666180817125036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/03/2018] [Accepted: 08/13/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND The use of indwelling Central Venous Access Devices (CVADs) is associated with the development of bloodstream infections. When CVADs are used to administer systemic antibiotics, particularly second- or higher-generation cephalosporins, there is a particular risk of developing Clostridium difficile infection. The overall bloodstream infection rate is estimated to be around 1.74 per 1000 Central Venous Catheter (CVC)-days. OBJECTIVE We hypothesised that daily oral administration of the anion-binding resin colestyramine (cholestyramine) would help prevent infections in those receiving intravenous antibiotic treatment via CVADs. METHOD A small case series is described of adult patients who received regular intravenous antibiotic treatment (ceftriaxone, daptomycin or vancomycin) for up to 40 weeks via indwelling CVADs; this represented a total of 357 CVC-days. In addition to following well-established strategies to prevent C. difficile infection, during the course of the intravenous antibiotic treatment the patients also received daily oral supplementation with 4 g colestyramine. RESULTS There were no untoward infectious events. In particular, none of the patients developed any symptoms or signs of C. difficile infection, whereas approximately one case of a bloodstream infection would have been expected. CONCLUSION It is suggested that oral colestyramine supplementation may help prevent such infection through its ability to bind C. difficile toxin A (TcdA) and C. difficile toxin B (TcdB); these toxins are able to gain entry into host cells through receptor-mediated endocytosis, while anti-toxin antibody responses to TcdA and TcdB have been shown to induce protection against C. difficile infection sequelae.
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Affiliation(s)
- Basant K Puri
- Department of Medicine, Imperial College London, London, United Kingdom
| | - Anne Derham
- Breakspear Medical Group, Hemel Hempstead, Hertfordshire, United Kingdom
| | - Jean A Monro
- Breakspear Medical Group, Hemel Hempstead, Hertfordshire, United Kingdom
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Chandrasekaran R, Lacy DB. The role of toxins in Clostridium difficile infection. FEMS Microbiol Rev 2017; 41:723-750. [PMID: 29048477 PMCID: PMC5812492 DOI: 10.1093/femsre/fux048] [Citation(s) in RCA: 210] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 10/10/2017] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile is a bacterial pathogen that is the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. The incidence, severity, mortality and healthcare costs associated with C. difficile infection (CDI) are rising, making C. difficile a major threat to public health. Traditional treatments for CDI involve use of antibiotics such as metronidazole and vancomycin, but disease recurrence occurs in about 30% of patients, highlighting the need for new therapies. The pathogenesis of C. difficile is primarily mediated by the actions of two large clostridial glucosylating toxins, toxin A (TcdA) and toxin B (TcdB). Some strains produce a third toxin, the binary toxin C. difficile transferase, which can also contribute to C. difficile virulence and disease. These toxins act on the colonic epithelium and immune cells and induce a complex cascade of cellular events that result in fluid secretion, inflammation and tissue damage, which are the hallmark features of the disease. In this review, we summarize our current understanding of the structure and mechanism of action of the C. difficile toxins and their role in disease.
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Affiliation(s)
- Ramyavardhanee Chandrasekaran
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37232, USA
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15
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Orrell KE, Zhang Z, Sugiman-Marangos SN, Melnyk RA. Clostridium difficile toxins A and B: Receptors, pores, and translocation into cells. Crit Rev Biochem Mol Biol 2017; 52:461-473. [DOI: 10.1080/10409238.2017.1325831] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kathleen E. Orrell
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Zhifen Zhang
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | | | - Roman A. Melnyk
- Molecular Medicine Program, The Hospital for Sick Children Research Institute, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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16
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Larabee JL, Bland SJ, Hunt JJ, Ballard JD. Intrinsic Toxin-Derived Peptides Destabilize and Inactivate Clostridium difficile TcdB. mBio 2017; 8:e00503-17. [PMID: 28512094 PMCID: PMC5433098 DOI: 10.1128/mbio.00503-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 04/24/2017] [Indexed: 01/05/2023] Open
Abstract
Clostridium difficile infection (CDI) is a major cause of hospital-associated, antibiotic-induced diarrhea, which is largely mediated by the production of two large multidomain clostridial toxins, TcdA and TcdB. Both toxins coordinate the action of specific domains to bind receptors, enter cells, and deliver a catalytic fragment into the cytosol. This results in GTPase inactivation, actin disassembly, and cytotoxicity. TcdB in particular has been shown to encode a region covering amino acids 1753 to 1851 that affects epitope exposure and cytotoxicity. Surprisingly, studies here show that several peptides derived from this region, which share the consensus sequence 1769NVFKGNTISDK1779, protect cells from the action of TcdB. One peptide, PepB2, forms multiple interactions with the carboxy-terminal region of TcdB, destabilizes TcdB structure, and disrupts cell binding. We further show that these effects require PepB2 to form a higher-order polymeric complex, a process that requires the central GN amino acid pair. These data suggest that TcdB1769-1779 interacts with repeat sequences in the proximal carboxy-terminal domain of TcdB (i.e., the CROP domain) to alter the conformation of TcdB. Furthermore, these studies provide insights into TcdB structure and functions that can be exploited to inactivate this critical virulence factor and ameliorate the course of CDI.IMPORTANCEClostridium difficile is a leading cause of hospital-associated illness that is often associated with antibiotic treatment. To cause disease, C. difficile secretes toxins, including TcdB, which is a multidomain intracellular bacterial toxin that undergoes conformational changes during cellular intoxication. This study describes the development of peptide-based inhibitors that target a region of TcdB thought to be critical for structural integrity of the toxin. The results show that peptides derived from a structurally important region of TcdB can be used to destabilize the toxin and prevent cellular intoxication. Importantly, this work provides a novel means of toxin inhibition that could in the future develop into a C. difficile treatment.
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Affiliation(s)
- Jason L Larabee
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Sarah J Bland
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jonathan J Hunt
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Jimmy D Ballard
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
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17
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Lambert GS, Baldwin MR. Evidence for dual receptor-binding sites in Clostridium difficile toxin A. FEBS Lett 2016; 590:4550-4563. [PMID: 27861794 DOI: 10.1002/1873-3468.12487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/10/2016] [Accepted: 10/24/2016] [Indexed: 12/24/2022]
Abstract
TcdA (308 kDa) and TcdB (270 kDa) disrupt the integrity of the intestinal epithelial barrier and provide an environment favorable for Clostridium difficile colonization. Recent evidence suggests that entry of TcdA into cells is mediated by at least two domains. Here, we report the characterization of a second receptor-binding domain (RBD2) for TcdA. While both the isolated combined repetitive oligopeptides (CROPs) and RBD2 fragments are rapidly internalized into cells under physiologic conditions, only the CROPs domain appreciably accumulates at the cell surface. Once internalized, CROPs and RBD2 are trafficked to late endosomal compartments. An internal deletion of RBD2 from TcdA holotoxin ablated toxicity in HT29 cells. These data are consistent with the recently proposed dual receptor model of cellular entry.
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Affiliation(s)
- Gregory S Lambert
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO, USA
| | - Michael R Baldwin
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO, USA
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19
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Chumbler NM, Rutherford SA, Zhang Z, Farrow MA, Lisher JP, Farquhar E, Giedroc DP, Spiller BW, Melnyk RA, Lacy DB. Crystal structure of Clostridium difficile toxin A. Nat Microbiol 2016; 1:15002. [PMID: 27571750 PMCID: PMC4976693 DOI: 10.1038/nmicrobiol.2015.2] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 09/18/2015] [Indexed: 02/04/2023]
Abstract
Clostridium difficile infection is the leading cause of hospital-acquired diarrhoea and pseudomembranous colitis. Disease is mediated by the actions of two toxins, TcdA and TcdB, which cause the diarrhoea, as well as inflammation and necrosis within the colon. The toxins are large (308 and 270 kDa, respectively), homologous (47% amino acid identity) glucosyltransferases that target small GTPases within the host. The multidomain toxins enter cells by receptor-mediated endocytosis and, upon exposure to the low pH of the endosome, insert into and deliver two enzymatic domains across the membrane. Eukaryotic inositol-hexakisphosphate (InsP6) binds an autoprocessing domain to activate a proteolysis event that releases the N-terminal glucosyltransferase domain into the cytosol. Here, we report the crystal structure of a 1,832-amino-acid fragment of TcdA (TcdA1832), which reveals a requirement for zinc in the mechanism of toxin autoprocessing and an extended delivery domain that serves as a scaffold for the hydrophobic α-helices involved in pH-dependent pore formation. A surface loop of the delivery domain whose sequence is strictly conserved among all large clostridial toxins is shown to be functionally important, and is highlighted for future efforts in the development of vaccines and novel therapeutics.
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Affiliation(s)
- Nicole M. Chumbler
- Chemical and Physical Biology Program, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Stacey A. Rutherford
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Zhifen Zhang
- Department of Biochemistry, University of Toronto and the Molecular Structure & Function Research Institute at The Hospital for Sick Children, Toronto, Ontario M5S 1A8, Canada
| | - Melissa A. Farrow
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - John P. Lisher
- Interdisciplinary Graduate Program in Biochemistry, Indiana University, Bloomington, Indiana 47405, USA
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | - Erik Farquhar
- Case Western Reserve University Center for Synchrotron Biosciences, National Synchrotron Light Source, Building 725, Brookhaven National Laboratory, New York 11973, USA
| | - David P. Giedroc
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA
| | - Benjamin W. Spiller
- Chemical and Physical Biology Program, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, USA
| | - Roman A. Melnyk
- Department of Biochemistry, University of Toronto and the Molecular Structure & Function Research Institute at The Hospital for Sick Children, Toronto, Ontario M5S 1A8, Canada
| | - D. Borden Lacy
- Chemical and Physical Biology Program, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37205, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37212, USA
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20
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Gerhard R. Receptors and Binding Structures for Clostridium difficile Toxins A and B. Curr Top Microbiol Immunol 2016; 406:79-96. [PMID: 27380268 DOI: 10.1007/82_2016_17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two characteristics of toxins A and B from C. difficile (TcdA, TcdB) are important for the understanding of the pathogenic effect of these homologous toxins. First, these toxins are huge single-chain but multidomain proteins that display their action intracellularly within the cytosol of host cells. And second, albeit various cell types highly differ in their sensitivity toward these toxins, no toxin-resistant cell type has been described yet. Investigation of receptor-mediated uptake of these toxins is very ambitious. It demands discrimination between cell surface binding, interaction with more than one functional receptor responsible for uptake as well as other functional receptors that recognize bacterial pathogens and are not necessarily related with endocytosis. The current understanding of a complex uptake process is that TcdB interacts with at least two facultative receptors that mediate entry into host cells by redundant endocytotic pathways. Although both homologous toxins do obviously not share the same receptors, this principle of redundant binding domains found for TcdB does also account for TcdA.
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Affiliation(s)
- Ralf Gerhard
- Institut für Toxikologie, Medizinische Hochschule, Hannover, Germany.
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21
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Zhang Y, Hamza T, Gao S, Feng H. Masking autoprocessing of Clostridium difficile toxin A by the C-terminus combined repetitive oligo peptides. Biochem Biophys Res Commun 2015; 459:259-263. [PMID: 25725153 DOI: 10.1016/j.bbrc.2015.02.095] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 02/17/2015] [Indexed: 10/23/2022]
Abstract
Clostridium difficile toxin A and B (TcdA and TcdB) are the major virulence factors of the bacterium, both of which consist of two enzymatic domains: an effector glucosyltransferase domain (GTD) and a cysteine protease domain (CPD) responsible for autocleavage and release of GTD. Although the CPDs from both toxins share a similar structure and mechanism of hexakisphosphate (InsP6)-induced activation, TcdA is substantially less sensitive to the autocleavage as compared with TcdB. In this study, we provided evidence of inter-domain regulation of CPD activity of TcdA and its autoprocessing. The C-terminus combined repetitive oligo peptides (CROPs) of TcdA reduced the accessibility of TcdB CPD to its substrate in a chimeric toxin TxB-Ar, consequently blocking autoprocessing. Moreover, interference of antibodies with the CROPs of full-length TcdA efficiently enhanced its GTD release. In conclusion, by utilizing chimeric toxins and specific antibodies, we identified that the CROPs of TcdA plays a crucial role in controlling the InsP6-mediated activation of CPD and autocleavage of GTD. Our data provides insights on the molecular mode of action of the C. difficile toxins.
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Affiliation(s)
- Yongrong Zhang
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA
| | - Therwa Hamza
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA
| | - Si Gao
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Dental School, Baltimore, MD 21201, USA.
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Puri BK, Hakkarainen-Smith JS, Monro JA. The potential use of cholestyramine to reduce the risk of developing Clostridium difficile-associated diarrhoea in patients receiving long-term intravenous ceftriaxone. Med Hypotheses 2014; 84:78-80. [PMID: 25497389 DOI: 10.1016/j.mehy.2014.11.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 11/11/2014] [Accepted: 11/26/2014] [Indexed: 12/14/2022]
Abstract
Intravenous pharmacotherapy with the third-generation cephalosporin ceftriaxone is unfortunately associated with a relatively high incidence of Clostridium difficile-associated diarrhoea. Cholestyramine (colestyramine) is an anion-binding resin which can bind luminal C.difficile toxin A (TcdA) and toxin B (TcdB) and which may be beneficial in the treatment of recurrent antibiotic-associated pseudomembranous colitis. We therefore hypothesised that concomitant oral cholestyramine might reduce the risk of C.difficile-associated diarrhoea in patients receiving long-term intravenous ceftriaxone. A pilot study was carried out in which it was found that only three out of 46 (6.5%) such patients being treated with 2 g ceftriaxone daily for Lyme borreliosis, who also received 4 g cholestyramine daily, developed C.difficile-associated diarrhoea. This is smaller than a published report of the incidence of this complication in six out of 26 (23.1%) patients following 1-3 days' treatment with 1 g intravenous ceftriaxone, but without oral cholestyramine (p=0.06). We therefore recommend that a larger, double-blind placebo-controlled trial be carried out to test this hypothesis.
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Affiliation(s)
- B K Puri
- Department of Medicine, Hammersmith Hospital, Imperial College London, UK.
| | | | - Jean A Monro
- Breakspear Medical Group, Hemel Hempstead, Hertfordshire, UK
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