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Jiang M, Shin J, Simeon R, Chang JY, Meng R, Wang Y, Shinde O, Li P, Chen Z, Zhang J. Structural dynamics of receptor recognition and pH-induced dissociation of full-length Clostridioides difficile Toxin B. PLoS Biol 2022; 20:e3001589. [PMID: 35324891 PMCID: PMC8982864 DOI: 10.1371/journal.pbio.3001589] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 04/05/2022] [Accepted: 03/02/2022] [Indexed: 12/14/2022] Open
Abstract
Clostridioides difficile secretes Toxin B (TcdB) as one of its major virulence factors, which binds to intestinal epithelial and subepithelial receptors, including frizzled proteins and chondroitin sulfate proteoglycan 4 (CSPG4). Here, we present cryo-EM structures of full-length TcdB in complex with the CSPG4 domain 1 fragment (D1401-560) at cytosolic pH and the cysteine-rich domain of frizzled-2 (CRD2) at both cytosolic and acidic pHs. CSPG4 specifically binds to the autoprocessing and delivery domains of TcdB via networks of salt bridges, hydrophobic and aromatic/proline interactions, which are disrupted upon acidification eventually leading to CSPG4 drastically dissociating from TcdB. In contrast, FZD2 moderately dissociates from TcdB under acidic pH, most likely due to its partial unfolding. These results reveal structural dynamics of TcdB during its preentry step upon endosomal acidification, which provide a basis for developing therapeutics against C. difficile infections.
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Affiliation(s)
- Mengqiu Jiang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Joonyoung Shin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Rudo Simeon
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, Texas, United States of America
| | - Jeng-Yih Chang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Ran Meng
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Yuhang Wang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Omkar Shinde
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Pingwei Li
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Zhilei Chen
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, College Station, Texas, United States of America
| | - Junjie Zhang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
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2
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Wicke N, Bedford MR, Howarth M. Gastrobodies are engineered antibody mimetics resilient to pepsin and hydrochloric acid. Commun Biol 2021; 4:960. [PMID: 34381153 PMCID: PMC8358037 DOI: 10.1038/s42003-021-02487-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 07/23/2021] [Indexed: 02/04/2023] Open
Abstract
Protein-based targeting reagents, such as antibodies and non-antibody scaffold proteins, are rapidly inactivated in the upper gastrointestinal (GI) tract. Hydrochloric acid in gastric juice denatures proteins and activates pepsin, concentrations of which reach 1 mg/mL in the mammalian stomach. Two stable scaffold proteins (nanobody and nanofitin), previously developed to be protease-resistant, were completely digested in less than 10 min at 100-fold lower concentration of pepsin than found in the stomach. Here we present gastrobodies, a protein scaffold derived from Kunitz soybean trypsin inhibitor (SBTI). SBTI is highly resistant to the challenges of the upper GI tract, including digestive proteases, pH 2 and bile acids. Computational prediction of SBTI's evolvability identified two nearby loops for randomization, to create a potential recognition surface which was experimentally validated by alanine scanning. We established display of SBTI on full-length pIII of M13 phage. Phage selection of gastrobody libraries against the glucosyltransferase domain of Clostridium difficile toxin B (GTD) identified hits with nanomolar affinity and enzyme inhibitory activity. Anti-GTD binders retained high stability to acid, digestive proteases and heat. Gastrobodies show resilience to exceptionally harsh conditions, which should provide a foundation for targeting and modulating function within the GI tract.
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Affiliation(s)
- Niels Wicke
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Mark Howarth
- Department of Biochemistry, University of Oxford, Oxford, UK.
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3
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Chen X, Yang X, de Anda J, Huang J, Li D, Xu H, Shields KS, Džunková M, Hansen J, Patel IJ, Yee EU, Golenbock DT, Grant MA, Wong GCL, Kelly CP. Clostridioides difficile Toxin A Remodels Membranes and Mediates DNA Entry Into Cells to Activate Toll-Like Receptor 9 Signaling. Gastroenterology 2020; 159:2181-2192.e1. [PMID: 32841647 PMCID: PMC8720510 DOI: 10.1053/j.gastro.2020.08.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/31/2020] [Accepted: 08/18/2020] [Indexed: 01/05/2023]
Abstract
BACKGROUND & AIMS Clostridioides difficile toxin A (TcdA) activates the innate immune response. TcdA co-purifies with DNA. Toll-like receptor 9 (TLR9) recognizes bacterial DNA to initiate inflammation. We investigated whether DNA bound to TcdA activates an inflammatory response in murine models of C difficile infection via activation of TLR9. METHODS We performed studies with human colonocytes and monocytes and macrophages from wild-type and TLR9 knockout mice incubated with TcdA or its antagonist (ODN TTAGGG) or transduced with vectors encoding TLR9 or small-interfering RNAs. Cytokine production was measured with enzyme-linked immunosorbent assay. We studied a transduction domain of TcdA (TcdA57-80), which was predicted by machine learning to have cell-penetrating activity and confirmed by synchrotron small-angle X-ray scattering. Intestines of CD1 mice, C57BL6J mice, and mice that express a form of TLR9 that is not activated by CpG DNA were injected with TcdA, TLR9 antagonist, or both. Enterotoxicity was estimated based on loop weight to length ratios. A TLR9 antagonist was tested in mice infected with C difficile. We incubated human colon explants with an antagonist of TLR9 and measured TcdA-induced production of cytokines. RESULTS The TcdA57-80 protein transduction domain had membrane remodeling activity that allowed TcdA to enter endosomes. TcdA-bound DNA entered human colonocytes. TLR9 was required for production of cytokines by cultured cells and in human colon explants incubated with TcdA. TLR9 was required in TcdA-induced mice intestinal secretions and in the survival of mice infected by C difficile. Even in a protease-rich environment, in which only fragments of TcdA exist, the TcdA57-80 domain organized DNA into a geometrically ordered structure that activated TLR9. CONCLUSIONS TcdA from C difficile can bind and organize bacterial DNA to activate TLR9. TcdA and TcdA fragments remodel membranes, which allows them to access endosomes and present bacterial DNA to and activate TLR9. Rather than inactivating the ability of DNA to bind TLR9, TcdA appears to chaperone and organize DNA into an inflammatory, spatially periodic structure.
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Affiliation(s)
- Xinhua Chen
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
| | - Xiaotong Yang
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA,Institute of Microbiology and Immunology, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Jaime de Anda
- Department of Bioengineering, Department of Chemistry and Biochemistry, California Nano Systems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jun Huang
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA,Department of Colorectal Surgery, the 6th Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Dan Li
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Hua Xu
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Kelsey S. Shields
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Mária Džunková
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Joshua Hansen
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | | | - Eric U. Yee
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Douglas T. Golenbock
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Marianne A. Grant
- Division of Molecular and Vascular Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Gerard C. L. Wong
- Department of Bioengineering, Department of Chemistry and Biochemistry, California Nano Systems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA,Corresponding Authors: Xinhua Chen, PhD, , or Gerard C. L. Wong, PhD,
| | - Ciarán P. Kelly
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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4
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Qi H, Sun Q, Ma Y, Wu P, Wang J. Advantages of Lateral Flow Assays Based on Fluorescent Submicrospheres and Quantum Dots for Clostridium difficile Toxin B Detection. Toxins (Basel) 2020; 12:toxins12110722. [PMID: 33227925 PMCID: PMC7699250 DOI: 10.3390/toxins12110722] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 01/05/2023] Open
Abstract
Clostridium difficile colitis is caused by a cytotoxin produced by the anaerobic bacteria C. difficile in the epithelial cells of the large intestine, particularly C. difficile toxin B (TcdB). However, the sensitivity of currently utilized C. difficile endotoxin determination methods has been called into question, and, therefore, more accurate and convenient detection methods are needed. Our study is the first to systematically compare fluorescent submicrosphere-based and quantum-dot nanobead-based lateral fluidity measurement methods (FMs-LFA and QDNBs-LFA) with toxin B quantification in fecal samples via sandwich analysis. The limits of detection (LOD) of FMs-LFA and QDNBs-LFA in the fecal samples were 0.483 and 0.297 ng/mL, respectively. TcdB analyses of the fecal samples indicated that the results of QDNBs-LFA and FMs-LFA were consistent with those of a commercial enzyme-linked immunosorbent assay (ELISA) test kit. The sensitivity of QDNBs-LFA was highly correlated with clinical diagnoses. Therefore, quantum dot nanobeads (QDNBs) are deemed highly suitable for lateral fluidity analyses, which would facilitate the implementation of portable and rapid on-the-spot applications, such as food hygiene and safety tests and onsite medical testing.
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Affiliation(s)
- Haonan Qi
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; (H.Q.); (Q.S.); (Y.M.)
| | - Qiuli Sun
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; (H.Q.); (Q.S.); (Y.M.)
| | - Yi Ma
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; (H.Q.); (Q.S.); (Y.M.)
| | - Peidian Wu
- National & Local United Engineering Lab of Rapid Diagnostic Test, Guangzhou Wondfo Biotech Co., Ltd., Guangzhou 510663, China;
| | - Jufang Wang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China; (H.Q.); (Q.S.); (Y.M.)
- Correspondence: ; Tel.: +86-20-3938-0626
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5
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Martins CS, Costa DVS, Lima BB, Leitäo RFC, Freire GE, Silva GFM, Pacífico DM, Abreu JG, Brito GAC. Clostridioides difficile Toxin A-Induced Wnt/β-Catenin Pathway Inhibition Is Mediated by Rac1 Glucosylation. Front Microbiol 2020; 11:1998. [PMID: 32983019 PMCID: PMC7483921 DOI: 10.3389/fmicb.2020.01998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/28/2020] [Indexed: 11/13/2022] Open
Abstract
Clostridioides difficile toxin A (TcdA) has been shown to inhibit cellular Wnt signaling, the major driving force behind the proliferation of epithelial cells in colonic crypts, likely through the inhibition of β-catenin nuclear translocation. Herein, we aimed to advance the understanding of this mechanism by replicating the findings in vivo and by investigating the specific role of Rac1, a member of the Rho GTPase family, on the inhibition of the Wnt-induced β-catenin nuclear translocation triggered by TcdA. To investigate the effects of TcdA on the Wnt/β-catenin pathway in vivo, we injected the ileal loops of C57BL/6 mice with TcdA [phosphate-buffered saline (PBS) as the control] to induce C. difficile disease-like ileitis. After 4 h post-injection, we obtained ileum tissue samples to assess Wnt signaling activation and cell proliferation through Western blotting, immunohistochemistry, and qPCR. To assess the role of Rac1 on Wnt signaling inhibition by TcdA, we transfected rat intestinal epithelial cells (IEC-6) with either a constitutively active Rac1 plasmid (pcDNA3-EGFP-Rac1-Q61L) or an empty vector, which served as the control. We incubated these cells with Wnt3a-conditioned medium (Wnt3a-CM) to induce Wnt/β-catenin pathway activation, and then challenged the cells with TcdA. We assessed Wnt signaling activation in vitro with TOP/FOPflash luciferase assays, determined nuclear β-catenin translocation by immunofluorescence, measured cyclin D1 protein expression by Western blotting, and quantified cell proliferation by Ki67 immunostaining. In vivo, TcdA decreased β-catenin, cyclin D1, and cMYC expression and inhibited the translocation of β-catenin into the nucleus in the ileum epithelial cells. In addition, TcdA suppressed cell proliferation and increased Wnt3a expression, but did not alter Rac1 gene expression in the ileum tissue. In vitro, constitutively active Rac1 prevented Wnt signaling inhibition by enabling the β-catenin nuclear translocation that had been blocked by TcdA. Our results show that TcdA inhibits Wnt/β-catenin pathway in vivo and demonstrate that this inhibition is likely caused by a Rac1-mediated mechanism.
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Affiliation(s)
- Conceição S Martins
- Postgraduate Program in Morphofunctional Sciences, Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Deiziane V S Costa
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Bruno B Lima
- Department of Medicine, Division of Cardiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Renata F C Leitäo
- Postgraduate Program in Morphofunctional Sciences, Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Gildênio E Freire
- Postgraduate Program in Morphofunctional Sciences, Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Guilherme F M Silva
- Department of Medical Sciences, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - Dvison M Pacífico
- Department of Medical Sciences, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
| | - José G Abreu
- Department of Anatomy, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Gerly A C Brito
- Postgraduate Program in Morphofunctional Sciences, Department of Morphology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil.,Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil
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6
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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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7
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Larabee JL, Hauck GD, Ballard JD. Cell-penetrating peptides derived from Clostridium difficile TcdB2 and a related large clostridial toxin. J Biol Chem 2017; 293:1810-1819. [PMID: 29247010 DOI: 10.1074/jbc.m117.815373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/12/2017] [Indexed: 12/15/2022] Open
Abstract
Clostridium difficile TcdB (2366 amino acid residues) is an intracellular bacterial toxin that binds to cells and enters the cytosol where it glucosylates small GTPases. In the current study, we examined a putative cell entry region of TcdB (amino acid residues 1753-1851) for short sequences that function as cell-penetrating peptides (CPPs). To screen for TcdB-derived CPPs, a panel of synthetic peptides was tested for the ability to enhance transferrin (Tf) association with cells. Four candidate CPPs were discovered, and further study on one peptide (PepB2) pinpointed an asparagine residue necessary for CPP activity. PepB2 mediated the cell entry of a wide variety of molecules including dextran, streptavidin, microspheres, and lentivirus particles. Of note, this uptake was dramatically reduced in the presence of the Na+/H+ exchange blocker and micropinocytosis inhibitor amiloride, suggesting that PepB2 invokes macropinocytosis. Moreover, we found that PepB2 had more efficient cell-penetrating activity than several other well-known CPPs (TAT, penetratin, Pep-1, and TP10). Finally, Tf assay-based screening of peptides derived from two other large clostridial toxins, TcdA and TcsL, uncovered two new TcdA-derived CPPs. In conclusion, we have identified six CPPs from large clostridial toxins and have demonstrated the ability of PepB2 to promote cell association and entry of several molecules through a putative fluid-phase macropinocytotic mechanism.
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Affiliation(s)
- Jason L Larabee
- From the Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Garrett D Hauck
- From the Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jimmy D Ballard
- From the Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
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8
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Kroh HK, Chandrasekaran R, Zhang Z, Rosenthal K, Woods R, Jin X, Nyborg AC, Rainey GJ, Warrener P, Melnyk RA, Spiller BW, Lacy DB. A neutralizing antibody that blocks delivery of the enzymatic cargo of Clostridium difficile toxin TcdB into host cells. J Biol Chem 2017; 293:941-952. [PMID: 29180448 DOI: 10.1074/jbc.m117.813428] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 11/08/2017] [Indexed: 12/14/2022] Open
Abstract
Clostridium difficile infection is the leading cause of hospital-acquired diarrhea and is mediated by the actions of two toxins, TcdA and TcdB. The toxins perturb host cell function through a multistep process of receptor binding, endocytosis, low pH-induced pore formation, and the translocation and delivery of an N-terminal glucosyltransferase domain that inactivates host GTPases. Infection studies with isogenic strains having defined toxin deletions have established TcdB as an important target for therapeutic development. Monoclonal antibodies that neutralize TcdB function have been shown to protect against C. difficile infection in animal models and reduce recurrence in humans. Here, we report the mechanism of TcdB neutralization by PA41, a humanized monoclonal antibody capable of neutralizing TcdB from a diverse array of C. difficile strains. Through a combination of structural, biochemical, and cell functional studies, involving X-ray crystallography and EM, we show that PA41 recognizes a single, highly conserved epitope on the TcdB glucosyltransferase domain and blocks productive translocation and delivery of the enzymatic cargo into the host cell. Our study reveals a unique mechanism of C. difficile toxin neutralization by a monoclonal antibody, which involves targeting a process that is conserved across the large clostridial glucosylating toxins. The PA41 antibody described here provides a valuable tool for dissecting the mechanism of toxin pore formation and translocation across the endosomal membrane.
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Affiliation(s)
- Heather K Kroh
- From the Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363
| | - Ramyavardhanee Chandrasekaran
- From the Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363
| | - Zhifen Zhang
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | | | - Rob Woods
- MedImmune LLC, Gaithersburg, Maryland 20878-2204
| | - Xiaofang Jin
- MedImmune LLC, Gaithersburg, Maryland 20878-2204
| | | | | | | | - Roman A Melnyk
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Benjamin W Spiller
- From the Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363.,Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232-6600, and
| | - D Borden Lacy
- From the Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2363, .,Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee 37212-2637
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9
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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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10
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Correction: Chen, S., et al. Identification of an Essential Region for Translocation of Clostridium difficile Toxin B. Toxins 2016, 8, 241. Toxins (Basel) 2016; 8:toxins8120352. [PMID: 27918428 PMCID: PMC5198547 DOI: 10.3390/toxins8120352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 11/16/2022] Open
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