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Schmidt G. Some Examples of Bacterial Toxins as Tools. Toxins (Basel) 2024; 16:202. [PMID: 38787054 PMCID: PMC11125981 DOI: 10.3390/toxins16050202] [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: 03/05/2024] [Revised: 04/18/2024] [Accepted: 04/20/2024] [Indexed: 05/25/2024] Open
Abstract
Pathogenic bacteria produce diverse protein toxins to disturb the host's defenses. This includes the opening of epithelial barriers to establish bacterial growth in deeper tissues of the host and to modulate immune cell functions. To achieve this, many toxins share the ability to enter mammalian cells, where they catalyze the modification of cellular proteins. The enzymatic activity is diverse and ranges from ribosyl- or glycosyl-transferase activity, the deamidation of proteins, and adenylate-cyclase activity to proteolytic cleavage. Protein toxins are highly active enzymes often with tight specificity for an intracellular protein or a protein family coupled with the intrinsic capability of entering mammalian cells. A broad understanding of their molecular mechanisms established bacterial toxins as powerful tools for cell biology. Both the enzymatic part and the pore-forming/protein transport capacity are currently used as tools engineered to study signaling pathways or to transport cargo like labeled compounds, nucleic acids, peptides, or proteins directly into the cytosol. Using several representative examples, this review is intended to provide a short overview of the state of the art in the use of bacterial toxins or parts thereof as tools.
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Affiliation(s)
- Gudula Schmidt
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Albertstr. 25, 79104 Freiburg, Germany
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2
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Charla R, Patil PP, Patil VS, Bhandare VV, Karoshi V, Balaganur V, Joshi RK, Harish DR, Roy S. Anti-Cholera toxin activity of selected polyphenols from Careya arborea, Punica granatum, and Psidium guajava. Front Cell Infect Microbiol 2023; 13:1106293. [PMID: 37113136 PMCID: PMC10126245 DOI: 10.3389/fcimb.2023.1106293] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 02/28/2023] [Indexed: 04/29/2023] Open
Abstract
Introduction Careya arborea, Punica granatum, and Psidium guajava are traditionally used to treat diarrheal diseases in India and were reported to show anti-Cholera toxin activity from our earlier studies. As polyphenols are reported to neutralize Cholera toxin (CT), the present study investigated the inhibitory activity of selected polyphenols from these plants against CTB binding to GM1 receptor using in silico, in vitro, and in vivo approaches. Methods Molecular modelling approach was used to investigate the intermolecular interactions of selected 20 polyphenolic compounds from three plants with CT using DOCK6. Based on intermolecular interactions, two phenolic acids, Ellagic acid (EA) and Chlorogenic acid (CHL); two flavonoids, Rutin (RTN) and Phloridzin (PHD) were selected along with their respective standards, Gallic acid (GA) and Quercetrin (QRTN). The stability of docked complexes was corroborated using molecular dynamics simulation. Furthermore, in vitro inhibitory activity of six compounds against CT was assessed using GM1 ELISA and cAMP assay. EA and CHL that showed prominent activity against CT in in vitro assays were investigated for their neutralizing activity against CT-induced fluid accumulation and histopathological changes in adult mouse. Results and discussion The molecular modelling study revealed significant structural stability of the CT-EA, CT-CHL, and CT-PHD complexes compared to their respective controls. All the selected six compounds significantly reduced CT-induced cAMP levels, whereas EA, CHL, and PHD exhibited > 50% binding inhibition of CT to GM1. The EA and CHL that showed prominent neutralization activity against CT from in vitro studies, also significantly decreased CT-induced fluid accumulation and histopathological changes in adult mouse. Our study identified bioactive compounds from these three plants against CT-induced diarrhea.
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Affiliation(s)
- Rajitha Charla
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
- KLE Academy of Higher Education and Research (KAHER), Belagavi, India
| | - Priyanka P. Patil
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
- KLE Academy of Higher Education and Research (KAHER), Belagavi, India
| | - Vishal S. Patil
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
- KLE Academy of Higher Education and Research (KAHER), Belagavi, India
| | - Vishwambhar V. Bhandare
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
- Department of Microbiology, Shivaji University, Kolhapur, India
| | - Veeresh Karoshi
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
| | - Venkanna Balaganur
- Indian Council of Agricultural Research – Krishi Vigyan Kendra, Bagalkot, Karnataka, India
- University of Agricultural Sciences, Dharwad, Karnataka, India
| | - Rajesh K. Joshi
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
| | - Darasaguppe R. Harish
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
- *Correspondence: Darasaguppe R. Harish, ; Subarna Roy,
| | - Subarna Roy
- Indian Council of Medical Research - National Institute of Traditional Medicine, Belagavi, Karnataka, India
- *Correspondence: Darasaguppe R. Harish, ; Subarna Roy,
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Ojiakor A, Gibbs RN, Chen Z, Gao X, Fowler CC. The evolutionary diversification of the Salmonella artAB toxin locus. Front Microbiol 2022; 13:1016438. [PMID: 36504768 PMCID: PMC9732031 DOI: 10.3389/fmicb.2022.1016438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/07/2022] [Indexed: 11/27/2022] Open
Abstract
Salmonella enterica is a diverse species of bacterial pathogens comprised of >2,500 serovars with variable host ranges and virulence properties. Accumulating evidence indicates that two AB5-type toxins, typhoid toxin and ArtAB toxin, contribute to the more severe virulence properties of the Salmonella strains that encode them. It was recently discovered that there are two distinct types of artAB-like genetic elements in Salmonella: those that encode ArtAB toxins (artAB elements) and those in which the artA gene is degraded and the ArtB homolog, dubbed PltC, serves as an alternative delivery subunit for typhoid toxin (pltC elements). Here, we take a multifaceted approach to explore the evolutionary diversification of artAB-like genetic elements in Salmonella. We identify 7 subtypes of ArtAB toxins and 4 different PltC sequence groups that are distributed throughout the Salmonella genus. Both artAB and pltC are encoded within numerous diverse prophages, indicating a central role for phages in their evolutionary diversification. Genetic and structural analyses revealed features that distinguish pltC elements from artAB and identified evolutionary adaptations that enable PltC to efficiently engage typhoid toxin A subunits. For both pltC and artAB, we find that the sequences of the B subunits are especially variable, particularly amongst amino acid residues that fine tune the chemical environment of their glycan binding pockets. This study provides a framework to delineate the remarkably complex collection of Salmonella artAB/pltC-like genetic elements and provides a window into the mechanisms of evolution for AB5-type toxins.
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Affiliation(s)
- Adaobi Ojiakor
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Rachel N. Gibbs
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Zhe Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xiang Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China,School of Life Sciences, Shandong University, Qingdao, China
| | - Casey C. Fowler
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada,*Correspondence: Casey C. Fowler,
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Ramm F, Jack L, Kaser D, Schloßhauer JL, Zemella A, Kubick S. Cell-Free Systems Enable the Production of AB5 Toxins for Diagnostic Applications. Toxins (Basel) 2022; 14:toxins14040233. [PMID: 35448842 PMCID: PMC9027097 DOI: 10.3390/toxins14040233] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 12/04/2022] Open
Abstract
Cell-free protein synthesis (CFPS) represents a versatile key technology for the production of toxic proteins. As a cell lysate, rather than viable cells, is used, the toxic effects on the host organism can be circumvented. The open nature of cell-free systems allows for the addition of supplements affecting protein concentration and folding. Here, we present the cell-free synthesis and functional characterization of two AB5 toxins, namely the cholera toxin (Ctx) and the heat-labile enterotoxin (LT), using two eukaryotic cell-free systems based on Chinese hamster ovary (CHO) and Spodoptera frugiperda (Sf21) cells. Through an iterative optimization procedure, the synthesis of the individual AB5 toxins was established, and the formation of multimeric structures could be shown by autoradiography. A functional analysis was performed using cell-based assays, thereby demonstrating that the LT complex induced the characteristic cell elongation of target cells after 24 h. The LT complex induced cell death at higher concentrations, starting at an initial concentration of 5 nM. The initial toxic effects of the Ctx multimer could already be detected at 4 nM. The detection and characterization of such AB5 toxins is of utmost importance, and the monitoring of intracellular trafficking facilitates the further identification of the mechanism of action of these toxins. We showed that the B-subunit of LT (LTB) could be fluorescently labeled using an LTB-Strep fusion protein, which is a proof-of-concept for future Trojan horse applications. Further, we performed a mutational analysis of the CtxA subunit as its template was modified, and an amber stop codon was inserted into CtxA’s active site. Subsequently, a non-canonical amino acid was site-specifically incorporated using bio-orthogonal systems. Finally, a fluorescently labeled CtxA protein was produced using copper-catalyzed click reactions as well as a Staudinger ligation. As expected, the modified Ctx multimer no longer induced toxic effects. In our study, we showed that CFPS could be used to study the active centers of toxins by inserting mutations. Additionally, this methodology can be applied for the design of Trojan horses and targeted toxins, as well as enabling the intracellular trafficking of toxins as a prerequisite for the analysis of the toxin’s mechanism of action.
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Affiliation(s)
- Franziska Ramm
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (L.J.); (D.K.); (J.L.S.); (A.Z.)
- Institute of Chemistry and Biochemistry—Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Lena Jack
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (L.J.); (D.K.); (J.L.S.); (A.Z.)
| | - Danny Kaser
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (L.J.); (D.K.); (J.L.S.); (A.Z.)
| | - Jeffrey L. Schloßhauer
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (L.J.); (D.K.); (J.L.S.); (A.Z.)
- Institute of Chemistry and Biochemistry—Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
| | - Anne Zemella
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (L.J.); (D.K.); (J.L.S.); (A.Z.)
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany; (F.R.); (L.J.); (D.K.); (J.L.S.); (A.Z.)
- Institute of Chemistry and Biochemistry—Biochemistry, Freie Universität Berlin, Takustr. 6, 14195 Berlin, Germany
- Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus–Senftenberg, Brandenburg Medical School Theodor Fontane and the University of Potsdam, 14476 Potsdam, Germany
- Correspondence:
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STxB as an Antigen Delivery Tool for Mucosal Vaccination. Toxins (Basel) 2022; 14:toxins14030202. [PMID: 35324699 PMCID: PMC8948715 DOI: 10.3390/toxins14030202] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/03/2022] [Accepted: 03/07/2022] [Indexed: 12/31/2022] Open
Abstract
Immunotherapy against cancer and infectious disease holds the promise of high efficacy with minor side effects. Mucosal vaccines to protect against tumors or infections disease agents that affect the upper airways or the lung are still lacking, however. One mucosal vaccine candidate is the B-subunit of Shiga toxin, STxB. In this review, we compare STxB to other immunotherapy vectors. STxB is a non-toxic protein that binds to a glycosylated lipid, termed globotriaosylceramide (Gb3), which is preferentially expressed by dendritic cells. We review the use of STxB for the cross-presentation of tumor or viral antigens in a MHC class I-restricted manner to induce humoral immunity against these antigens in addition to polyfunctional and persistent CD4+ and CD8+ T lymphocytes capable of protecting against viral infection or tumor growth. Other literature will be summarized that documents a powerful induction of mucosal IgA and resident memory CD8+ T cells against mucosal tumors specifically when STxB-antigen conjugates are administered via the nasal route. It will also be pointed out how STxB-based vaccines have been shown in preclinical cancer models to synergize with other therapeutic modalities (immune checkpoint inhibitors, anti-angiogenic therapy, radiotherapy). Finally, we will discuss how molecular aspects such as low immunogenicity, cross-species conservation of Gb3 expression, and lack of toxicity contribute to the competitive positioning of STxB among the different DC targeting approaches. STxB thereby appears as an original and innovative tool for the development of mucosal vaccines in infectious diseases and cancer.
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Abstract
Typhoid toxin is an A2B5 protein toxin and an important virulence factor for the human-adapted bacterial pathogen Salmonella enterica serovar Typhi, the causative agent of typhoid fever. Typhoid toxin contains two enzymatic subunits, PltA and CdtB, which dock onto a pentameric delivery platform composed of the protein PltB. It was recently reported that the same enzymatic subunits can assemble with a different delivery platform composed of the protein PltC, forming a distinct version of typhoid toxin. However, the differences in structure and receptor specificity between the PltC and PltB typhoid toxins remain unknown. Here, we determined atomic-level structures of the pentameric PltC subunit, the fully assembled PltC typhoid toxin, and the PltC pentamers in complex with glycan receptors. Biochemical and structural analyses indicate that PltB and PltC are unable to form heteromeric delivery complexes due to electrostatic repulsion at the subunit interface and thus form separate toxins only. We further observed that, despite low sequence similarity between PltB and PltC, they interact with PltA in a similar manner but that PltC exhibits stronger electrostatic interactions with PltA, enabling it to outcompete PltB in toxin assembly. The ligand-bound atomic structures of PltC show an additional glycan binding site not found in PltB and glycan array analysis indicates that PltB and PltC exhibit significant differences in glycan binding specificity. Collectively, this study offers atomic-level insights into how S. Typhi produces two distinct versions of typhoid toxin, thereby generating functional diversity in this key virulence factor. IMPORTANCE Typhoid fever is a devastating disease that kills more than 115,000 people every year and is caused by Salmonella Typhi. Typhoid toxin, exclusively produced by S. Typhi, was demonstrated to be responsible for the pathogenesis of typhoid fever. Typhoid toxin consists of a pentameric delivery B subunit to transport the catalytic A subunits into the host cell through binding of the glycan receptors. Recent study shows that S. Typhi encodes two homologous delivery B subunits that are able to associate with the same active subunits to produce alternative toxins with distinct functional characteristics. Here, we show that the two delivery subunits can form only homopentameric delivery platforms that compete to associate with typhoid toxin's active subunits and that the two resulting toxins have distinct glycan-binding properties that confer distinct functional traits. These findings highlight the unique assembly and functional diversification of typhoid toxins.
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Novel Aspects of the SubA Subunit of the Subtilase Cytotoxin. Toxins (Basel) 2022; 14:toxins14020156. [PMID: 35202183 PMCID: PMC8876466 DOI: 10.3390/toxins14020156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 02/04/2023] Open
Abstract
The subtilase cytotoxin (SubAB) belongs to the family of AB5 toxins and is produced together with Shiga toxin (Stx) by certain Stx-producing E. coli strains (STEC). For most AB-type toxins, it is assumed that cytotoxic effects can only be induced by a complete holotoxin complex consisting of SubA and SubB. However, it has been shown for SubAB that the enzymatically active subunit SubA, without its transport and binding domain SubB, induces cell death in different eukaryotic cell lines. Interestingly, the molecular structure of SubA resembles that of the SubAB complex. SubA alone is capable of binding to cells and then being taken up autonomously. Once inside the host cell, SubA is transported, similar to the SubAB holotoxin, via a retrograde transport into the endoplasmatic reticulum (ER). In the ER, it exhibits its enzymatic activity by cleaving the chaperone BiP/GRP78 and thereby triggering cell death. Therefore, the existence of toxic single SubA subunits that have not found a B-pentamer for holotoxin assembly might improve the pathogenic potential of subtilase-producing strains. Moreover, from a pharmacological aspect, SubA might be an interesting molecule for the targeted transport of therapeutic molecules into the ER, in order to investigate and specifically modulate processes in the context of ER stress-associated diseases. Since recent studies on bacterial AB5 toxins contributed mainly to the understanding of the biology of AB-type holotoxins, this mini-review specifically focus on that recently observed single A-effect of the subtilase cytotoxin and addresses whether a fundamental shift of the traditional AB5 paradigm might be required.
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Bint E Naser SF, Su H, Liu HY, Manzer ZA, Chao Z, Roy A, Pappa AM, Salleo A, Owens RM, Daniel S. Detection of Ganglioside-Specific Toxin Binding with Biomembrane-Based Bioelectronic Sensors. ACS APPLIED BIO MATERIALS 2021; 4:7942-7950. [DOI: 10.1021/acsabm.1c00878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Samavi Farnush Bint E Naser
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Hui Su
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Han-Yuan Liu
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Zachary A. Manzer
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Zhongmou Chao
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Arpita Roy
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Anna-Maria Pappa
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K
| | - Alberto Salleo
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Róisín M. Owens
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K
| | - Susan Daniel
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
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Balmforth MR, Haigh J, Kumar V, Dai W, Tiede C, Tomlinson DC, Deuchars J, Webb ME, Turnbull WB. Piggybacking on the Cholera Toxin: Identification of a CTB-Binding Protein as an Approach for Targeted Delivery of Proteins to Motor Neurons. Bioconjug Chem 2021; 32:2205-2212. [PMID: 34565149 DOI: 10.1021/acs.bioconjchem.1c00373] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A significant unmet need exists for the delivery of biologic drugs such as polypeptides or nucleic acids to the central nervous system for the treatment and understanding of neurodegenerative diseases. Naturally occurring bacterial toxins have been considered as tools to meet this need. However, due to the complexity of tethering macromolecular drugs to toxins and the inherent dangers of working with large quantities of recombinant toxins, no such route has been successfully exploited. Developing a method where a bacterial toxin's nontoxic targeting subunit can be assembled with a drug immediately prior to in vivo administration has the potential to circumvent some of these issues. Using a phage-display screen, we identified two antibody mimetics, anticholera toxin Affimer (ACTA)-A2 and ACTA-C6 that noncovalently associate with the nonbinding face of the cholera toxin B-subunit. In a first step toward the development of a nonviral motor neuron drug-delivery vehicle, we show that Affimers can be selectively delivered to motor neurons in vivo.
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Affiliation(s)
- Matthew R Balmforth
- School of Chemistry, School of Biomedical Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - Jessica Haigh
- School of Chemistry, School of Biomedical Sciences and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - Vajinder Kumar
- School of Chemistry and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
- Akal University, Talwandi Sabo, Punjab 151302, India
| | - Wenyue Dai
- School of Chemistry and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - Christian Tiede
- School of Molecular and Cellular Biology, and Astbury Centre for Structural and Molecular Biology, University of Leeds, Faculty of Biological Sciences, Leeds LS2 9JT, U.K
| | - Darren C Tomlinson
- School of Molecular and Cellular Biology, and Astbury Centre for Structural and Molecular Biology, University of Leeds, Faculty of Biological Sciences, Leeds LS2 9JT, U.K
| | - Jim Deuchars
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Michael E Webb
- School of Chemistry and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
| | - W Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K
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Higgs PL, Appleton JL, Turnbull WB, Fulton DA. Exploiting the Structural Metamorphosis of Polymers to 'Wrap' Micron-Sized Spherical Objects. Chemistry 2021; 27:17647-17654. [PMID: 34665484 DOI: 10.1002/chem.202103216] [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: 09/04/2021] [Indexed: 11/07/2022]
Abstract
There is growing interest in developing methods to 'wrap' nano- and micron-sized biological objects within films that may offer protection, enhance their stability or improve performance. We describe the successful 'wrapping' of lectin-decorated microspheres, which serve as appealing model micron-sized objects, within cross-linked polymer film. This approach utilizes polymer chains able to undergo a structural metamorphosis, from being intramolecularly cross-linked to intermolecularly cross-linked, a process that is triggered by polymer concentration upon the particle surface. Experiments demonstrate that both complementary molecular recognition and the dynamic covalent nature of the crosslinker are required for successful 'wrapping' to occur. This work is significant as it suggests that nano- and micron-sized biological objects such as virus-like particles, bacteria or mammalian cells-all of which may benefit from additional environmental protection or stabilization in emerging applications-may also be 'wrapped' by this approach.
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Affiliation(s)
- Patrick L Higgs
- Chemistry-School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Jordan L Appleton
- Chemistry-School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - W Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural MolecularBiology, University of Leeds, Leeds, LS2 9JT, UK
| | - David A Fulton
- Chemistry-School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
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Proteome-wide prediction of bacterial carbohydrate-binding proteins as a tool for understanding commensal and pathogen colonisation of the vaginal microbiome. NPJ Biofilms Microbiomes 2021; 7:49. [PMID: 34131152 PMCID: PMC8206207 DOI: 10.1038/s41522-021-00220-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/20/2021] [Indexed: 12/16/2022] Open
Abstract
Bacteria use carbohydrate-binding proteins (CBPs), such as lectins and carbohydrate-binding modules (CBMs), to anchor to specific sugars on host surfaces. CBPs in the gut microbiome are well studied, but their roles in the vagina microbiome and involvement in sexually transmitted infections, cervical cancer and preterm birth are largely unknown. We established a classification system for lectins and designed Hidden Markov Model (HMM) profiles for data mining of bacterial genomes, resulting in identification of >100,000 predicted bacterial lectins available at unilectin.eu/bacteria. Genome screening of 90 isolates from 21 vaginal bacterial species shows that those associated with infection and inflammation produce a larger CBPs repertoire, thus enabling them to potentially bind a wider array of glycans in the vagina. Both the number of predicted bacterial CBPs and their specificities correlated with pathogenicity. This study provides new insights into potential mechanisms of colonisation by commensals and potential pathogens of the reproductive tract that underpin health and disease states.
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Functional approaches to the study of G-protein-coupled receptors in postmortem brain tissue: [ 35S]GTPγS binding assays combined with immunoprecipitation. Pharmacol Rep 2021; 73:1079-1095. [PMID: 33876404 DOI: 10.1007/s43440-021-00253-z] [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: 02/08/2021] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 10/21/2022]
Abstract
G-protein-coupled receptors (GPCRs) have an enormous biochemical importance as they bind to diverse extracellular ligands and regulate a variety of physiological and pathological responses. G-protein activation measures the functional consequence of receptor occupancy at one of the earliest receptor-mediated events. Receptor coupling to G-proteins promotes the GDP/GTP exchange on Gα subunits. Thus, modulation of the binding of the poorly hydrolysable GTP analog [35S]GTPγS to the Gα-protein subunit can be used as a functional approach to quantify GPCR interaction with agonist, antagonist or inverse agonist drugs. In order to determine receptor-mediated selective activation of the different Gα-proteins, [35S]GTPγS binding assays combined with immunodetection by specific antibodies have been developed and applied to physiological and pathological brain conditions. Currently, immunoprecipitation with magnetic beads and scintillation proximity assays are the most habitual techniques for this purpose. The present review summarizes the different procedures, advantages and limitations of the [35S]GTPγS binding assays combined with selective Gα-protein sequestration methods. Experience of functional coupling of several GPCRs to different Gα-proteins and recommendations for optimal performance in brain membranes are described. One of the biggest opportunities opened by these techniques is that they enable evaluation of biased agonism in the native tissue, which results in high interest in drug discovery. The available results derived from application of these functional methodologies to study GPCR dysfunctions in neuro-psychiatric disorders are also described. In conclusion, [35S]GTPγS binding combined with antibody-mediated immunodetection represents an useful method to separately evaluate the functional activity of drugs acting on GPCRs over each Gα-protein subtype.
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Protein Sensing Device with Multi-Recognition Ability Composed of Self-Organized Glycopeptide Bundle. Int J Mol Sci 2020; 22:ijms22010366. [PMID: 33396442 PMCID: PMC7795492 DOI: 10.3390/ijms22010366] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/29/2020] [Accepted: 12/29/2020] [Indexed: 01/09/2023] Open
Abstract
We designed and synthesized amphiphilic glycopeptides with glucose or galactose at the C-terminals. We observed the protein-induced structural changes of the amphiphilic glycopeptide assembly in the lipid bilayer membrane using transmission electron microscopy (TEM) and Fourier transform infrared reflection-absorption spectra (FTIR-RAS) measurements. The glycopeptides re-arranged to form a bundle that acted as an ion channel due to the interaction among the target protein and the terminal sugar groups of the glycopeptides. The bundle in the lipid bilayer membrane was fixed on a gold-deposited quartz crystal microbalance (QCM) electrode by the membrane fusion method. The protein-induced re-arrangement of the terminal sugar groups formed a binding site that acted as a receptor, and the re-binding of the target protein to the binding site induced the closing of the channel. We monitored the detection of target proteins by the changes of the electrochemical properties of the membrane. The response current of the membrane induced by the target protein recognition was expressed by an equivalent circuit consisting of resistors and capacitors when a triangular voltage was applied. We used peanut lectin (PNA) and concanavalin A (ConA) as target proteins. The sensing membrane induced by PNA shows the specific response to PNA, and the ConA-induced membrane responded selectively to ConA. Furthermore, PNA-induced sensing membranes showed relatively low recognition ability for lectin from Ricinus Agglutinin (RCA120) and mushroom lectin (ABA), which have galactose binding sites. The protein-induced self-organization formed the spatial arrangement of the sugar chains specific to the binding site of the target protein. These findings demonstrate the possibility of fabricating a sensing device with multi-recognition ability that can recognize proteins even if the structure is unknown, by the protein-induced self-organization process.
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Antunez EE, Mahon CS, Tong Z, Voelcker NH, Müllner M. A Regenerable Biosensing Platform for Bacterial Toxins. Biomacromolecules 2020; 22:441-453. [PMID: 33320642 DOI: 10.1021/acs.biomac.0c01318] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Waterborne diarrheal diseases such as travelers' diarrhea and cholera remain a threat to public health in many countries. Rapid diagnosis of an infectious disease is critical in preventing the escalation of a disease outbreak into an epidemic. Many of the diagnostic tools for infectious diseases employed today are time-consuming and require specialized laboratory settings and trained personnel. There is hence a pressing need for fit-for-purpose point-of-care diagnostic tools with emphasis in sensitivity, specificity, portability, and low cost. We report work toward thermally reversible biosensors for detection of the carbohydrate-binding domain of the Escherichia coli heat-labile enterotoxin (LTB), a toxin produced by enterotoxigenic E. coli strains, which causes travelers' diarrhea. The biosensing platform is a hybrid of two materials, combining the optical properties of porous silicon (pSi) interferometric transducers and a thermoresponsive multivalent glycopolymer, to enable recognition of LTB. Analytical performance of our biosensors allows us to detect, using a label-free format, sub-micromolar concentrations of LTB in solution as low as 0.135 μM. Furthermore, our platform shows a temperature-mediated "catch-and-release" behavior, an exciting feature with potential for selective protein capture, multiple readouts, and regeneration of the sensor over consecutive cycles of use.
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Affiliation(s)
- E Eduardo Antunez
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.,Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility, Clayton, Victoria 3168, Australia
| | - Clare S Mahon
- Department of Chemistry, Durham University, Durham DH1 3LE, U.K
| | - Ziqiu Tong
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Nicolas H Voelcker
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.,Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility, Clayton, Victoria 3168, Australia
| | - Markus Müllner
- Key Centre for Polymers and Colloids, School of Chemistry, The University of Sydney, Sydney 2006, New South Wales, Australia.,The University of Sydney Nano Institute (Sydney Nano), Sydney 2006, New South Wales, Australia
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15
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Valid Presumption of Shiga Toxin-Mediated Damage of Developing Erythrocytes in EHEC-Associated Hemolytic Uremic Syndrome. Toxins (Basel) 2020; 12:toxins12060373. [PMID: 32512916 PMCID: PMC7354503 DOI: 10.3390/toxins12060373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 02/06/2023] Open
Abstract
The global emergence of clinical diseases caused by enterohemorrhagic Escherichia coli (EHEC) is an issue of great concern. EHEC release Shiga toxins (Stxs) as their key virulence factors, and investigations on the cell-damaging mechanisms toward target cells are inevitable for the development of novel mitigation strategies. Stx-mediated hemolytic uremic syndrome (HUS), characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury, is the most severe outcome of an EHEC infection. Hemolytic anemia during HUS is defined as the loss of erythrocytes by mechanical disruption when passing through narrowed microvessels. The formation of thrombi in the microvasculature is considered an indirect effect of Stx-mediated injury mainly of the renal microvascular endothelial cells, resulting in obstructions of vessels. In this review, we summarize and discuss recent data providing evidence that HUS-associated hemolytic anemia may arise not only from intravascular rupture of erythrocytes, but also from the extravascular impairment of erythropoiesis, the development of red blood cells in the bone marrow, via direct Stx-mediated damage of maturing erythrocytes, leading to “non-hemolytic” anemia.
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16
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Cervin J, Boucher A, Youn G, Björklund P, Wallenius V, Mottram L, Sampson NS, Yrlid U. Fucose-Galactose Polymers Inhibit Cholera Toxin Binding to Fucosylated Structures and Galactose-Dependent Intoxication of Human Enteroids. ACS Infect Dis 2020; 6:1192-1203. [PMID: 32134631 PMCID: PMC7227030 DOI: 10.1021/acsinfecdis.0c00009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
![]()
A promising strategy to limit cholera
severity involves blockers
mimicking the canonical cholera toxin ligand (CT) ganglioside GM1.
However, to date the efficacies of most of these blockers have been
evaluated in noncellular systems that lack ligands other than GM1.
Importantly, the CT B subunit (CTB) has a noncanonical site that binds
fucosylated structures, which in contrast to GM1 are highly expressed
in the human intestine. Here we evaluate the capacity of norbornene
polymers displaying galactose and/or fucose to block CTB binding to
immobilized protein-linked glycan structures and also to primary human
and murine small intestine epithelial cells (SI ECs). We show that
the binding of CTB to human SI ECs is largely dependent on the noncanonical
binding site, and interference with the canonical site has a limited
effect while the opposite is observed with murine SI ECs. The galactose–fucose
polymer blocks binding to fucosylated glycans but not to GM1. However,
the preincubation of CT with the galactose–fucose polymer only
partially blocks toxic effects on cultured human enteroid cells, while
preincubation with GM1 completely blocks CT-mediated secretion. Our
results support a model whereby the binding of fucose to the noncanonical
site places CT in close proximity to scarcely expressed galactose
receptors such as GM1 to enable binding via the canonical site leading
to CT internalization and intoxication. Our finding also highlights
the importance of complementing CTB binding studies with functional
intoxication studies when assessing the efficacy inhibitors of CT.
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Affiliation(s)
- Jakob Cervin
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Andrew Boucher
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Gyusaang Youn
- Department of Chemistry, Stony Brook University, Stony Brook, New York, 11794-3400, United States
| | - Per Björklund
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital/Östra, 416 85 Gothenburg, Sweden
| | - Ville Wallenius
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital/Östra, 416 85 Gothenburg, Sweden
| | - Lynda Mottram
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Nicole S. Sampson
- Department of Chemistry, Stony Brook University, Stony Brook, New York, 11794-3400, United States
| | - Ulf Yrlid
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, 405 30 Gothenburg, Sweden
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Gao H, Zhang J, Lou J, Li J, Qin Q, Shi Q, Zhang Y, Kan B. Direct Binding and Regulation by Fur and HapR of the Intermediate Regulator and Virulence Factor Genes Within the ToxR Virulence Regulon in Vibrio cholerae. Front Microbiol 2020; 11:709. [PMID: 32362889 PMCID: PMC7181404 DOI: 10.3389/fmicb.2020.00709] [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: 01/16/2020] [Accepted: 03/26/2020] [Indexed: 01/30/2023] Open
Abstract
Cholera toxin (CT) and toxin coregulated pilus (TCP, TcpA is the major subunit) are two major virulence factors of Vibrio cholerae, both of which play critical roles in developing severe diarrhea in human. Expression of CT and TCP is under the tight control of the regulatory cascade known as the ToxR virulence regulon, which is composed of three regulators ToxR, TcpP, and ToxT. Besides, their expression is also regulated by the quorum sensing (QS) master regulator HapR and the regulatory protein Fur. Though transcription of tcpP, toxT, and/or tcpA are reported to be regulated by HapR and Fur, to date there are no studies to verify their direct regulations. In the present study, we showed that HapR directly repress the transcription of tcpP and tcpA by binding to their promoter regions, and possibly repress toxT transcription in an indirect manner. Fur directly activated the transcription of tcpP, toxT, and tcpA by binding to their promoters. Taking account of the sequential expression of hapR, fur, tcpP, toxT, and tcpA in the different growth phases of V. cholerae, we deduce that at the early mid-logarithmic growth phase, Fur binds to the promoters of tcpP, toxT, and tcpA to activate their transcription; while at the later mid-logarithmic growth phase, HapR can bind to the promoters of tcpP and tcpA to repress their transcription. Our study reveals the new recognition in the virulence regulatory pathways in V. cholerae and suggests the complicated and subtle regulation network with the growth density dependence.
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Affiliation(s)
- He Gao
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jingyun Zhang
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jing Lou
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jie Li
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qin Qin
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Qiannan Shi
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yiquan Zhang
- School of Medicine, Jiangsu University, Zhenjiang, China
| | - Biao Kan
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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18
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Ordanini S, Celentano W, Bernardi A, Cellesi F. Mannosylated brush copolymers based on poly(ethylene glycol) and poly(ε-caprolactone) as multivalent lectin-binding nanomaterials. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:2192-2206. [PMID: 31807405 PMCID: PMC6880840 DOI: 10.3762/bjnano.10.212] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/23/2019] [Indexed: 06/10/2023]
Abstract
A class of linear and four-arm mannosylated brush copolymers based on poly(ethylene glycol) and poly(ε-caprolactone) is presented here. The synthesis through ring-opening and atom transfer radical polymerizations provided high control over molecular weight and functionality. A post-polymerization azide-alkyne cycloaddition allowed for the formation of glycopolymers with different mannose valencies (1, 2, 4, and 8). In aqueous media, these macromolecules formed nanoparticles that were able to bind lectins, as investigated by concanavalin A binding assay. The results indicate that carbohydrate-lectin interactions can be tuned by the macromolecular architecture and functionality, hence the importance of these macromolecular properties in the design of targeted anti-pathogenic nanomaterials.
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Affiliation(s)
- Stefania Ordanini
- Department of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di Milano, via Mancinelli 7, Milano 20131, Italy
| | - Wanda Celentano
- Department of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di Milano, via Mancinelli 7, Milano 20131, Italy
- Humanitas Research Hospital, Via Manzoni 56, Rozzano, Milano 20089, Italy
| | - Anna Bernardi
- Department of Chemistry, Università degli Studi di Milano, via Golgi 19, Milano 20133, Italy
| | - Francesco Cellesi
- Department of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di Milano, via Mancinelli 7, Milano 20131, Italy
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19
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Rustmeier NH, Strebl M, Stehle T. The Symmetry of Viral Sialic Acid Binding Sites-Implications for Antiviral Strategies. Viruses 2019; 11:v11100947. [PMID: 31615155 PMCID: PMC6832341 DOI: 10.3390/v11100947] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/02/2019] [Accepted: 10/09/2019] [Indexed: 12/12/2022] Open
Abstract
Virus infections are initiated by the attachment of the viral particle to protein or carbohydrate receptors on the host cell. Sialic acid-bearing glycan structures are prominently displayed at the cell surface, and, consequently, these structures can function as receptors for a large number of diverse viruses. Structural biology research has helped to establish the molecular bases for many virus–sialic acid interactions. Due to the icosahedral 532 point group symmetry that underlies many viral capsids, the receptor binding sites are frequently arranged in a highly symmetric fashion and linked by five-fold, three-fold, or two-fold rotation axes. For the inhibition of viral attachment, one emerging strategy is based on developing multivalent sialic acid-based inhibitors that can simultaneously engage several of these binding sites, thus binding viral capsids with high avidity. In this review, we will evaluate the structures of non-enveloped virus capsid proteins bound to sialylated glycan receptors and discuss the potential of these structures for the development of potent antiviral attachment inhibitors.
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Affiliation(s)
- Nils H Rustmeier
- Interfaculty Institute of Biochemistry, University of Tuebingen, 72076 Tuebingen, Baden-Wuerttemberg, Germany.
| | - Michael Strebl
- Interfaculty Institute of Biochemistry, University of Tuebingen, 72076 Tuebingen, Baden-Wuerttemberg, Germany.
| | - Thilo Stehle
- Interfaculty Institute of Biochemistry, University of Tuebingen, 72076 Tuebingen, Baden-Wuerttemberg, Germany.
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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20
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Crystal structures of cholera toxin in complex with fucosylated receptors point to importance of secondary binding site. Sci Rep 2019; 9:12243. [PMID: 31439922 PMCID: PMC6706398 DOI: 10.1038/s41598-019-48579-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 08/02/2019] [Indexed: 01/15/2023] Open
Abstract
Cholera is a life-threatening diarrhoeal disease caused by the human pathogen Vibrio cholerae. Infection occurs after ingestion of the bacteria, which colonize the human small intestine and secrete their major virulence factor – the cholera toxin (CT). The GM1 ganglioside is considered the primary receptor of the CT, but recent studies suggest that also fucosylated receptors such as histo-blood group antigens are important for cellular uptake and toxicity. Recently, a special focus has been on the histo-blood group antigen Lewisx (Lex), however, where and how the CT binds to Lex remains unclear. Here we report the high-resolution crystal structure (1.5 Å) of the receptor-binding B-subunits of the CT bound to the Lex trisaccharide, and complementary quantitative binding data for CT holotoxins. Lex, and also l-fucose alone, bind to the secondary binding site of the toxin, distinct from the GM1 binding site. In contrast, fucosyl-GM1 mainly binds to the primary binding site due to high-affinity interactions of its GM1 core. Lex is the first histo-blood group antigen of non-secretor phenotype structurally investigated in complex with CT. Together with the quantitative binding data, this allows unique insight into why individuals with non-secretor phenotype are more prone to severe cholera than so-called ‘secretors’.
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21
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Alternate subunit assembly diversifies the function of a bacterial toxin. Nat Commun 2019; 10:3684. [PMID: 31417089 PMCID: PMC6695444 DOI: 10.1038/s41467-019-11592-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 07/04/2019] [Indexed: 11/27/2022] Open
Abstract
Bacterial toxins with an AB5 architecture consist of an active (A) subunit inserted into a ring-like platform comprised of five delivery (B) subunits. Salmonella Typhi, the cause of typhoid fever, produces an unusual A2B5 toxin known as typhoid toxin. Here, we report that upon infection of human cells, S. Typhi produces two forms of typhoid toxin that have distinct delivery components but share common active subunits. The two typhoid toxins exhibit different trafficking properties, elicit different effects when administered to laboratory animals, and are expressed using different regulatory mechanisms and in response to distinct metabolic cues. Collectively, these results indicate that the evolution of two typhoid toxin variants has conferred functional versatility to this virulence factor. More broadly, this study reveals a new paradigm in toxin biology and suggests that the evolutionary expansion of AB5 toxins was likely fueled by the plasticity inherent to their structural design coupled to the functional versatility afforded by the combination of homologous toxin components. Salmonella Typhi produces the typhoid toxin. Here, Fowler et al. show that S. Typhi produces two forms of typhoid toxin that are differentially regulated and display different trafficking properties and different effects when administered to laboratory animals.
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22
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23
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Abstract
Many bacterial toxins catalyze the transfer of ADP-ribose from nicotinamide adenine dinucleotide (NAD) to a host protein. Greater than 35 bacterial ADP-ribosyltransferase toxins (bARTTs) have been identified. ADP-ribosylation of host proteins may be specific or promiscuous. Despite this diversity, bARTTs share a common reaction mechanism, three-dimensional active site structure, and a conserved active site glutamic acid. Here, we describe how to measure the ADP-ribosylation of host proteins as purified proteins or within a cell lysate.
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24
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Krueger E, Brown AC. Inhibition of bacterial toxin recognition of membrane components as an anti-virulence strategy. J Biol Eng 2019; 13:4. [PMID: 30820243 PMCID: PMC6380060 DOI: 10.1186/s13036-018-0138-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 12/27/2018] [Indexed: 12/21/2022] Open
Abstract
Over recent years, the development of new antibiotics has not kept pace with the rate at which bacteria develop resistance to these drugs. For this reason, many research groups have begun to design and study alternative therapeutics, including molecules to specifically inhibit the virulence of pathogenic bacteria. Because many of these pathogenic bacteria release protein toxins, which cause or exacerbate disease, inhibition of the activity of bacterial toxins is a promising anti-virulence strategy. In this review, we describe several approaches to inhibit the initial interactions of bacterial toxins with host cell membrane components. The mechanisms by which toxins interact with the host cell membrane components have been well-studied over the years, leading to the identification of therapeutic targets, which have been exploited in the work described here. We review efforts to inhibit binding to protein receptors and essential membrane lipid components, complex assembly, and pore formation. Although none of these molecules have yet been demonstrated in clinical trials, the in vitro and in vivo results presented here demonstrate their promise as novel alternatives and/or complements to traditional antibiotics.
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Affiliation(s)
- Eric Krueger
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015 USA
| | - Angela C. Brown
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015 USA
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25
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Specificity of Escherichia coli Heat-Labile Enterotoxin Investigated by Single-Site Mutagenesis and Crystallography. Int J Mol Sci 2019; 20:ijms20030703. [PMID: 30736336 PMCID: PMC6386978 DOI: 10.3390/ijms20030703] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 01/31/2019] [Indexed: 12/25/2022] Open
Abstract
Diarrhea caused by enterotoxigenic Escherichia coli (ETEC) is one of the leading causes of mortality in children under five years of age and is a great burden on developing countries. The major virulence factor of the bacterium is the heat-labile enterotoxin (LT), a close homologue of the cholera toxin. The toxins bind to carbohydrate receptors in the gastrointestinal tract, leading to toxin uptake and, ultimately, to severe diarrhea. Previously, LT from human- and porcine-infecting ETEC (hLT and pLT, respectively) were shown to have different carbohydrate-binding specificities, in particular with respect to N-acetyllactosamine-terminating glycosphingolipids. Here, we probed 11 single-residue variants of the heat-labile enterotoxin with surface plasmon resonance spectroscopy and compared the data to the parent toxins. In addition we present a 1.45 Å crystal structure of pLTB in complex with branched lacto-N-neohexaose (Galβ4GlcNAcβ6[Galβ4GlcNAcβ3]Galβ4Glc). The largest difference in binding specificity is caused by mutation of residue 94, which links the primary and secondary binding sites of the toxins. Residue 95 (and to a smaller extent also residues 7 and 18) also contribute, whereas residue 4 shows no effect on monovalent binding of the ligand and may rather be important for multivalent binding and avidity.
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27
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FURUKAWA K, OHMI Y, KONDO Y, BHUIYAN RH, TAJIMA O, ZHANG P, OHKAWA Y, FURUKAWA K. Elucidation of the enigma of glycosphingolipids in the regulation of inflammation and degeneration - Great progress over the last 70 years. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:136-149. [PMID: 30853699 PMCID: PMC6541724 DOI: 10.2183/pjab.95.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
Since globotetraosylceramide was defined as a major glycosphingolipid in human erythrocytes, various glycolipids have been found in normal cells and diseased organs. However, the implications of their polymorphic structures in the function of individual cells and tissues have not been clarified. Genetic manipulation of glycosphingolipids in cultured cells and experimental animals has enabled us to substantially elucidate their roles. In fact, great progress has been achieved in the last 70 years in revealing that glycolipids are essential in the maintenance of integrity of nervous tissues and other organs. Furthermore, the correct composition of glycosphingolipids has been shown to be critical for the protection against inflammation and degeneration. Here, we summarized historic information and current knowledge about glycosphingolipids, with a focus on their involvement in inflammation and degeneration. This topic is significant for understanding the biological responses to various stresses, because glycosphingolipids play roles in the interaction with various intrinsic and extrinsic factors. These findings are also important for the application of therapeutic interventions of various diseases.
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Affiliation(s)
- Koichi FURUKAWA
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yuhsuke OHMI
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
| | - Yuji KONDO
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Robiul H. BHUIYAN
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
| | - Orie TAJIMA
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
| | - Pu ZHANG
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yuki OHKAWA
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
| | - Keiko FURUKAWA
- Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan
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28
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Yang YJ, Mai DJ, Dursch TJ, Olsen BD. Nucleopore-Inspired Polymer Hydrogels for Selective Biomolecular Transport. Biomacromolecules 2018; 19:3905-3916. [DOI: 10.1021/acs.biomac.8b00556] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Yun Jung Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Danielle J. Mai
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Thomas J. Dursch
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Bradley D. Olsen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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29
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Riol CD, Dietrich R, Märtlbauer E, Jessberger N. Consumed Foodstuffs Have a Crucial Impact on the Toxic Activity of Enteropathogenic Bacillus cereus. Front Microbiol 2018; 9:1946. [PMID: 30174669 PMCID: PMC6107707 DOI: 10.3389/fmicb.2018.01946] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/31/2018] [Indexed: 11/13/2022] Open
Abstract
Enteropathogenic Bacillus cereus cause diarrhea due to the production of enterotoxins in the intestine. To start this process, spores have to be ingested together with contaminated food and survive the stomach passage. In this study, the influence of consumed foodstuffs on spore survival as well as on cytotoxicity toward colon epithelial cells was investigated. Spore survival of 20 enteropathogenic and apathogenic B. cereus strains during simulated stomach passage was highly strain-specific and did not correlate with the toxic potential. Survival of three tested strains was strain-specifically altered by milk products. Whereas milk, a follow-on formula and rice pudding had only little influence, spores seemed to be protected by milk products with high fat content such as whipped cream and mascarpone. Furthermore, tested milk products decreased the toxic activity of three B. cereus strains toward CaCo-2 cells. Investigating the individual components, lactoferrin, a skim milk powder and vitamins C, B5 and A showed the most inhibiting effects. On the other hand, biotin, vitamin B3 and another skim milk powder even enhanced cytotoxicity. Further studies suggested that these inhibiting effects result only partially from inhibiting cell binding, but rather from blocking the interaction between the single enterotoxin components.
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Affiliation(s)
- Claudia Da Riol
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
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30
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Pishesha N, Ingram JR, Ploegh HL. Sortase A: A Model for Transpeptidation and Its Biological Applications. Annu Rev Cell Dev Biol 2018; 34:163-188. [PMID: 30110557 DOI: 10.1146/annurev-cellbio-100617-062527] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Molecular biologists and chemists alike have long sought to modify proteins with substituents that cannot be installed by standard or even advanced genetic approaches. We here describe the use of transpeptidases to achieve these goals. Living systems encode a variety of transpeptidases and peptide ligases that allow for the enzyme-catalyzed formation of peptide bonds, and protein engineers have used directed evolution to enhance these enzymes for biological applications. We focus primarily on the transpeptidase sortase A, which has become popular over the past few years for its ability to perform a remarkably wide variety of protein modifications, both in vitro and in living cells.
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Affiliation(s)
- Novalia Pishesha
- Program in Molecular and Cellular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA; .,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jessica R Ingram
- Department of Cancer Immunology and Virology, Dana Farber Cancer Institute, Boston, Massachusetts 02215, USA
| | - Hidde L Ploegh
- Program in Molecular and Cellular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA;
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31
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Kumar V, Turnbull WB. Carbohydrate inhibitors of cholera toxin. Beilstein J Org Chem 2018; 14:484-498. [PMID: 29520310 PMCID: PMC5827775 DOI: 10.3762/bjoc.14.34] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 02/08/2018] [Indexed: 01/17/2023] Open
Abstract
Cholera is a diarrheal disease caused by a protein toxin released by Vibrio cholera in the host's intestine. The toxin enters intestinal epithelial cells after binding to specific carbohydrates on the cell surface. Over recent years, considerable effort has been invested in developing inhibitors of toxin adhesion that mimic the carbohydrate ligand, with particular emphasis on exploiting the multivalency of the toxin to enhance activity. In this review we introduce the structural features of the toxin that have guided the design of diverse inhibitors and summarise recent developments in the field.
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Affiliation(s)
- Vajinder Kumar
- Department of Chemistry, Akal University, Talwandi Sabo, Punjab, India
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK
| | - W Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK
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32
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Mahon CS, McGurk CJ, Watson SMD, Fascione MA, Sakonsinsiri C, Turnbull WB, Fulton DA. Molecular Recognition-Mediated Transformation of Single-Chain Polymer Nanoparticles into Crosslinked Polymer Films. Angew Chem Int Ed Engl 2017; 56:12913-12918. [PMID: 28805991 PMCID: PMC5656938 DOI: 10.1002/anie.201706379] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Indexed: 12/05/2022]
Abstract
We describe single-chain polymer nanoparticles (SCNPs) possessing intramolecular dynamic covalent crosslinks that can transform into polymer films through a molecular recognition-mediated crosslinking process. The SCNPs utilise molecular recognition with surface-immobilised proteins to concentrate upon a substrate, bringing the SCNPs into close spatial proximity with one another and allowing their dynamic covalent crosslinkers to undergo intra- to interpolymer chain crosslinking leading to the formation of polymeric film. SCNPs must possess both the capacity for specific molecular recognition and a dynamic nature to their intramolecular crosslinkers to form polymer films, and an investigation of the initial phase of film formation indicates it proceeds from features which form upon the surface then grow predominantly in the xy directions. This approach to polymer film formation presents a potential method to "wrap" surfaces displaying molecular recognition motifs-which could potentially include viral, cellular and bacterial surfaces or artificial surfaces displaying multivalent recognition motifs-within a layer of polymer film.
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Affiliation(s)
- Clare S. Mahon
- Chemical Nanoscience LaboratorySchool of ChemistryNewcastle UniversityNewcastle-upon-TyneNE1 7RUUK
- School of Chemistry and Astbury Centre for Structural Molecular BiologyUniversity of LeedsLeedsLS2 9JTUK
- Department of ChemistryUniversity of YorkHeslingtonYorkYO10 5DDUK
| | - Christopher J. McGurk
- Chemical Nanoscience LaboratorySchool of ChemistryNewcastle UniversityNewcastle-upon-TyneNE1 7RUUK
| | - Scott M. D. Watson
- Chemical Nanoscience LaboratorySchool of ChemistryNewcastle UniversityNewcastle-upon-TyneNE1 7RUUK
| | | | - Chadamas Sakonsinsiri
- School of Chemistry and Astbury Centre for Structural Molecular BiologyUniversity of LeedsLeedsLS2 9JTUK
- Department of BiochemistryFaculty of MedicineKhon Kean UniversityMuang DistrictKhon Kaen40002Thailand
| | - W. Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural Molecular BiologyUniversity of LeedsLeedsLS2 9JTUK
| | - David A. Fulton
- Chemical Nanoscience LaboratorySchool of ChemistryNewcastle UniversityNewcastle-upon-TyneNE1 7RUUK
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33
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Mahon CS, McGurk CJ, Watson SMD, Fascione MA, Sakonsinsiri C, Turnbull WB, Fulton DA. Molecular Recognition-Mediated Transformation of Single-Chain Polymer Nanoparticles into Crosslinked Polymer Films. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201706379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Clare S. Mahon
- Chemical Nanoscience Laboratory; School of Chemistry; Newcastle University; Newcastle-upon-Tyne NE1 7RU UK
- School of Chemistry and Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds LS2 9JT UK
- Department of Chemistry; University of York; Heslington York YO10 5DD UK
| | - Christopher J. McGurk
- Chemical Nanoscience Laboratory; School of Chemistry; Newcastle University; Newcastle-upon-Tyne NE1 7RU UK
| | - Scott M. D. Watson
- Chemical Nanoscience Laboratory; School of Chemistry; Newcastle University; Newcastle-upon-Tyne NE1 7RU UK
| | - Martin A. Fascione
- Department of Chemistry; University of York; Heslington York YO10 5DD UK
| | - Chadamas Sakonsinsiri
- School of Chemistry and Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds LS2 9JT UK
- Department of Biochemistry; Faculty of Medicine; Khon Kean University; Muang District Khon Kaen 40002 Thailand
| | - W. Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural Molecular Biology; University of Leeds; Leeds LS2 9JT UK
| | - David A. Fulton
- Chemical Nanoscience Laboratory; School of Chemistry; Newcastle University; Newcastle-upon-Tyne NE1 7RU UK
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34
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Chang SJ, Song J, Galán JE. Receptor-Mediated Sorting of Typhoid Toxin during Its Export from Salmonella Typhi-Infected Cells. Cell Host Microbe 2017; 20:682-689. [PMID: 27832592 DOI: 10.1016/j.chom.2016.10.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 09/16/2016] [Accepted: 10/09/2016] [Indexed: 11/30/2022]
Abstract
Typhoid toxin is an essential virulence factor of Salmonella Typhi, the cause of typhoid fever. Typhoid toxin is secreted into the lumen of Salmonella-containing vacuole (SCV), after which it is packaged into vesicle carrier intermediates and released extracellularly through incompletely understood mechanisms. Following export, the toxin targets cells by interacting with human-specific Neu5Ac-terminated glycan receptors. We show that typhoid toxin is sorted from the SCV into vesicle carrier intermediates via interactions of its B subunit, PltB, with specific lumenal sialylated glycan packaging receptors. Cells deficient in N-glycosylation or the synthesis of specific gangliosides or displaying Neu5Gc-terminated, as opposed to Neu5Ac-terminated, glycans do not support typhoid toxin export. Additionally, typhoid toxin packaging requires the specific SCV environment, as toxin produced by an S. Typhi mutant with impaired trafficking is not properly sorted into vesicles. These results reveal how the exotoxin of an intracellular pathogen engages host pathways for packaging and release.
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Affiliation(s)
- Shu-Jung Chang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jeongmin Song
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
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35
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Characterization of pertussis-like toxin from Salmonella spp. that catalyzes ADP-ribosylation of G proteins. Sci Rep 2017; 7:2653. [PMID: 28572615 PMCID: PMC5454059 DOI: 10.1038/s41598-017-02517-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/04/2017] [Indexed: 12/17/2022] Open
Abstract
Salmonella Typhimurium definitive phage type (DT) 104 produces a pertussis-like toxin (ArtAB-DT104), which catalyzes ADP-ribosylation of pertussis toxin sensitive G proteins. However, the prevalence of ArtAB and its toxicity have not been established. We report here that, in addition to DT104, S. Worthington, and S. bongori, produce ArtAB homologs, designated ArtAB-SW and ArtAB-Sb, respectively. We purified and characterized these ArtAB toxins, which comprise a 27-kDa A subunit (ArtA) and 13.8-kDa pentameric B subunits (ArtB). While the sequence of the A subunit, which is ADP-ribosyltransferase, is similar to the A subunit sequences of other ArtABs, the B subunit of ArtAB-Sb is divergent compared to the B subunit sequences of other ArtABs. Intraperitoneal injection of purified ArtABs was fatal in mice; the 50% lethal doses of ArtAB-DT104 and ArtAB-SW were lower than that of ArtAB-Sb, suggesting that ArtB plays an influential role in the toxicity of ArtABs. ArtABs catalyzed ADP-ribosylation of G proteins in RAW 264.7 murine macrophage-like cells, and increased intracellular cyclic AMP levels. ArtAB-DT104 and ArtAB-SW, but not ArtAB-Sb, stimulated insulin secretion in mice; however, unlike Ptx, ArtABs did not induce leukocytosis. This disparity in biological activity may be explained by differences in ADP-ribosylation of target G proteins.
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36
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Heggelund JE, Mackenzie A, Martinsen T, Heim JB, Cheshev P, Bernardi A, Krengel U. Towards new cholera prophylactics and treatment: Crystal structures of bacterial enterotoxins in complex with GM1 mimics. Sci Rep 2017; 7:2326. [PMID: 28539625 PMCID: PMC5443773 DOI: 10.1038/s41598-017-02179-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/07/2017] [Indexed: 01/08/2023] Open
Abstract
Cholera is a life-threatening disease in many countries, and new drugs are clearly needed. C-glycosidic antagonists may serve such a purpose. Here we report atomic-resolution crystal structures of three such compounds in complexes with the cholera toxin. The structures give unprecedented atomic details of the molecular interactions and show how the inhibitors efficiently block the GM1 binding site. These molecules are well suited for development into low-cost prophylactic drugs, due to their relatively easy synthesis and their resistance to glycolytic enzymes. One of the compounds links two toxin B-pentamers in the crystal structure, which may yield improved inhibition through the formation of toxin aggregates. These structures can spark the improved design of GM1 mimics, either alone or as multivalent inhibitors connecting multiple GM1-binding sites. Future developments may further include compounds that link the primary and secondary binding sites. Serving as decoys, receptor mimics may lessen symptoms while avoiding the use of antibiotics.
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Affiliation(s)
- Julie Elisabeth Heggelund
- Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315, Blindern, Norway. .,School of Biomedical Sciences, University of Leeds, LS2 9JT Leeds, UK and School of Pharmacy, University of Oslo, P.O. Box 1068, NO-0316, Blindern, Norway.
| | - Alasdair Mackenzie
- Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315, Blindern, Norway.,Alere Technologies AS, Kjelsåsveien 161, NO-0884, Oslo, Norway
| | - Tobias Martinsen
- Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315, Blindern, Norway
| | - Joel Benjamin Heim
- Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315, Blindern, Norway
| | - Pavel Cheshev
- Universita' degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133, Milano, Italy.,Skolkovo innovation center, Office 229, OC Technopark bld. 2, Lugovaya str. 4, 143026, Moscow, Russia
| | - Anna Bernardi
- Universita' degli Studi di Milano, Dipartimento di Chimica, via Golgi 19, 20133, Milano, Italy
| | - Ute Krengel
- Department of Chemistry, University of Oslo, P.O. Box 1033, NO-0315, Blindern, Norway.
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37
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Hatlem D, Heggelund JE, Burschowsky D, Krengel U, Kristiansen PE. 1H, 13C, 15N backbone assignment of the human heat-labile enterotoxin B-pentamer and chemical shift mapping of neolactotetraose binding. BIOMOLECULAR NMR ASSIGNMENTS 2017; 11:99-104. [PMID: 28243889 DOI: 10.1007/s12104-017-9728-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 02/16/2017] [Indexed: 06/06/2023]
Abstract
The major virulence factor of enterotoxigenic Escherichia coli is the heat-labile enterotoxin (LT), an AB5 toxin closely related to the cholera toxin. LT consists of six subunits, the catalytically active A-subunit and five B-subunits arranged as a pentameric ring (LTB), which enable the toxin to bind to the epithelial cells in the intestinal lumen. LTB has two recognized binding sites; the primary binding site is responsible for anchoring the toxin to its main receptor, the GM1-ganglioside, while the secondary binding site recognizes blood group antigens. Herein, we report the 1H, 13C, 15N main chain assignment of LTB from human isolates (hLTB; 103 a.a. per subunit, with a total molecular mass of 58.5 kDa). The secondary structure was predicted based on 13C', 13Cα, 13Cβ, 1HN and 15N chemical shifts and compared to a published crystal structure of LTB. Neolactotetraose (NEO) was titrated to hLTB and chemical shift perturbations were measured. The chemical shift perturbations were mapped onto the crystal structure, confirming that NEO binds to the primary binding site of hLTB and competes with GM1-binding. Our new data further lend support to the hypothesis that binding at the primary binding site is transmitted to the secondary binding site of the toxin, where it may influence the binding to blood group antigens.
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Affiliation(s)
- Daniel Hatlem
- Department of Chemistry, University of Oslo, Blindern, P.O. Box 1033, 0315, Oslo, Norway
- Department of Biosciences, University of Oslo, Blindern, P.O. Box 1066, 0316, Oslo, Norway
| | - Julie E Heggelund
- Department of Chemistry, University of Oslo, Blindern, P.O. Box 1033, 0315, Oslo, Norway
- School of Pharmacy, University of Oslo, Blindern, P.O. Box 1068, 0316, Oslo, Norway
| | - Daniel Burschowsky
- Department of Chemistry, University of Oslo, Blindern, P.O. Box 1033, 0315, Oslo, Norway
- Department of Molecular and Cell Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Ute Krengel
- Department of Chemistry, University of Oslo, Blindern, P.O. Box 1033, 0315, Oslo, Norway.
| | - Per E Kristiansen
- Department of Biosciences, University of Oslo, Blindern, P.O. Box 1066, 0316, Oslo, Norway.
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38
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The Molecular Basis of Toxins' Interactions with Intracellular Signaling via Discrete Portals. Toxins (Basel) 2017; 9:toxins9030107. [PMID: 28300784 PMCID: PMC5371862 DOI: 10.3390/toxins9030107] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/02/2017] [Accepted: 03/04/2017] [Indexed: 12/20/2022] Open
Abstract
An understanding of the molecular mechanisms by which microbial, plant or animal-secreted toxins exert their action provides the most important element for assessment of human health risks and opens new insights into therapies addressing a plethora of pathologies, ranging from neurological disorders to cancer, using toxinomimetic agents. Recently, molecular and cellular biology dissecting tools have provided a wealth of information on the action of these diverse toxins, yet, an integrated framework to explain their selective toxicity is still lacking. In this review, specific examples of different toxins are emphasized to illustrate the fundamental mechanisms of toxicity at different biochemical, molecular and cellular- levels with particular consideration for the nervous system. The target of primary action has been highlighted and operationally classified into 13 sub-categories. Selected examples of toxins were assigned to each target category, denominated as portal, and the modulation of the different portal’s signaling was featured. The first portal encompasses the plasma membrane lipid domains, which give rise to pores when challenged for example with pardaxin, a fish toxin, or is subject to degradation when enzymes of lipid metabolism such as phospholipases A2 (PLA2) or phospholipase C (PLC) act upon it. Several major portals consist of ion channels, pumps, transporters and ligand gated ionotropic receptors which many toxins act on, disturbing the intracellular ion homeostasis. Another group of portals consists of G-protein-coupled and tyrosine kinase receptors that, upon interaction with discrete toxins, alter second messengers towards pathological levels. Lastly, subcellular organelles such as mitochondria, nucleus, protein- and RNA-synthesis machineries, cytoskeletal networks and exocytic vesicles are also portals targeted and deregulated by other diverse group of toxins. A fundamental concept can be drawn from these seemingly different toxins with respect to the site of action and the secondary messengers and signaling cascades they trigger in the host. While the interaction with the initial portal is largely determined by the chemical nature of the toxin, once inside the cell, several ubiquitous second messengers and protein kinases/ phosphatases pathways are impaired, to attain toxicity. Therefore, toxins represent one of the most promising natural molecules for developing novel therapeutics that selectively target the major cellular portals involved in human physiology and diseases.
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Glycol chitosan: A stabilizer of lipid rafts in the intestinal brush border. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:360-367. [PMID: 28034633 DOI: 10.1016/j.bbamem.2016.12.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/29/2016] [Accepted: 12/23/2016] [Indexed: 01/09/2023]
Abstract
Chitosan is a polycationic polysaccharide consisting of β-(1-4)-linked glucosamine units and due to its mucoadhesive properties, chemical derivatives of chitosan are potential candidates as enhancers for transmucosal drug delivery. Recently, glycol chitosan (GC), a soluble derivative of chitosan, was shown to bind specifically to lipid raft domains in model bilayers. The small intestinal brush border membrane has a unique lipid raft composition with high amounts of glycolipids cross-linked by lectins, and the aim of the present work therefore was to study the interaction of FITC-conjugated GC (FITC-GC) with the small intestinal epithelium. Using organ culture of pig jejunal mucosal explants as a model system, we observed widespread binding of luminal FITC-GC to the brush border. Only little uptake via constitutive endocytosis into apical early endosomes occurred, unless endocytosis was induced by the simultaneous presence of cholera toxin B subunit (CTB). Biochemically, GC bound to microvillus membrane vesicles and caused a change in the density profile of detergent resistant membranes (DRMs). Collectively, the results showed that FITC-GC binds passively to lipid raft domains in the brush border, i.e. without inducing endocytosis like CTB. Instead, and unlike CTB, FITC-GC seems to exert a stabilizing, detergent-protective effect on the lipid raft organization of the brush border.
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40
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Zhang L, Li Z, Shi T, La X, Li H, Li Z. Design, purification and assessment of GRP78 binding peptide-linked Subunit A of Subtilase cytotoxic for targeting cancer cells. BMC Biotechnol 2016; 16:65. [PMID: 27585649 PMCID: PMC5009487 DOI: 10.1186/s12896-016-0294-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 08/16/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Targeted therapies for cancer, especially the malignant cancer, are always restricted by the deficiency of tumor-specific drug delivery methods. Subtilase cytotoxic is a virulent cytotoxin, and the subunit A (SubA) of it is able to destroy the structure of glucose-regulated protein 78 (GRP78) to induce cell apoptosis, and to be expected as anti-cancer drugs, however, the ubiquitous receptor of subunit B of Subtilase cytotoxic (SubB) restricts its application on cancer therapy. RESULTS The present study constructed and expressed a fusion protein of GBP-SubA in E. coli Rosetta (DE3) system, in which the subunit B of Subtilase cytotoxic was replaced by GRP78 binding peptide (GBP). The fusion protein was expressed in inclusion body form. Subsequently, the denaturation/renaturation process and Ni-column purification were performed. Our data indicated the purified GBP-SubA could bind GRP78 existed on cancer cell surface specifically, internalize into cells to inactivate intracellular GRP78 and induce apoptosis. Moreover, the apoptosis induction effect of GBP-SubA was enhanced obviously along with the increased cancer cell surface GBP78. CONCLUSIONS It indicates that the recombinant GBP-SubA possesses the dual functions of GBP and SubA to induce cancer cell apoptosis specifically, revealing that GBP-SubA holds important implications for developing as an anti-cancer peptide drug. A schematic representation of the construction and function of GBP-SubA.
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Affiliation(s)
- Lichao Zhang
- Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan, 030006, China.,School of Life Science, Shanxi University, Taiyuan, 030006, China
| | - Zongwei Li
- Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan, 030006, China
| | - Tonglin Shi
- Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan, 030006, China
| | - Xiaoqin La
- Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan, 030006, China
| | - Hanqing Li
- School of Life Science, Shanxi University, Taiyuan, 030006, China.
| | - Zhuoyu Li
- Institute of Biotechnology, Key Laboratory of Chemical Biology and Molecular Engineering of National Ministry of Education, Shanxi University, Taiyuan, 030006, China. .,College of Life Science, Zhejiang Chinese Medical University, Hangzhou, 310053, China.
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41
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Kumar V, Yadav N, Kartha KPR. Synthetic multivalent ligands for cholera & cholera-like toxins: Protected cyclic neoglycopeptides. Carbohydr Res 2016; 431:47-55. [PMID: 27309341 DOI: 10.1016/j.carres.2016.05.011] [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: 04/13/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 10/21/2022]
Abstract
Synthesis of a set of novel glycopeptide analogues as potential cholera/cholera-like toxin inhibitors in their protected form is described. They include di-, tri-, tetra- and pentavalent scaffolds. The synthetic steps were achieved using a combination of solvent-free mechanochemical as well as the conventional solution-phase reactions. During the conventional DIC-HOBt-mediated peptide coupling followed for the preparation of certain glycopeptide analogues an interesting in situ Fmoc deprotection was observed which has been demonstrated to hold potential for synthesiszing glycopeptides/neoglycopeptides with extended polyamide chains.
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Affiliation(s)
- Vajinder Kumar
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), S.A.S. Nagar, Punjab 160062, India
| | - Narender Yadav
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), S.A.S. Nagar, Punjab 160062, India
| | - K P Ravindranathan Kartha
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), S.A.S. Nagar, Punjab 160062, India.
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42
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Typhoid toxin provides a window into typhoid fever and the biology of Salmonella Typhi. Proc Natl Acad Sci U S A 2016; 113:6338-44. [PMID: 27222578 DOI: 10.1073/pnas.1606335113] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Salmonella Typhi is the cause of typhoid fever, a disease that has challenged humans throughout history and continues to be a major public health concern. Unlike infections with most other Salmonellae, which result in self-limiting gastroenteritis, typhoid fever is a life-threatening systemic disease. Furthermore, in contrast to most Salmonellae, which can infect a broad range of hosts, S. Typhi is a strict human pathogen. The unique features of S. Typhi pathogenesis and its stringent host specificity have been a long-standing puzzle. The discovery of typhoid toxin not only has provided major insight into these questions but also has offered unique opportunities to develop novel therapeutic and prevention strategies to combat typhoid fever.
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43
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High-Resolution Crystal Structures Elucidate the Molecular Basis of Cholera Blood Group Dependence. PLoS Pathog 2016; 12:e1005567. [PMID: 27082955 PMCID: PMC4833353 DOI: 10.1371/journal.ppat.1005567] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/21/2016] [Indexed: 11/19/2022] Open
Abstract
Cholera is the prime example of blood-group-dependent diseases, with individuals of blood group O experiencing the most severe symptoms. The cholera toxin is the main suspect to cause this relationship. We report the high-resolution crystal structures (1.1-1.6 Å) of the native cholera toxin B-pentamer for both classical and El Tor biotypes, in complexes with relevant blood group determinants and a fragment of its primary receptor, the GM1 ganglioside. The blood group A determinant binds in the opposite orientation compared to previously published structures of the cholera toxin, whereas the blood group H determinant, characteristic of blood group O, binds in both orientations. H-determinants bind with higher affinity than A-determinants, as shown by surface plasmon resonance. Together, these findings suggest why blood group O is a risk factor for severe cholera.
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Zuilhof H. Fighting Cholera One-on-One: The Development and Efficacy of Multivalent Cholera-Toxin-Binding Molecules. Acc Chem Res 2016; 49:274-85. [PMID: 26760438 DOI: 10.1021/acs.accounts.5b00480] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A series of diseases, ranging from cholera via travelers' diarrhea to hamburger disease, are caused by bacterially produced toxic proteins. In particular, a toxic protein unit is brought into the host cell upon binding to specific membrane-bound oligosaccharides on the host cell membrane. For example, the protein that causes cholera, cholera toxin (CT), has five identical, symmetrically placed binding pockets (B proteins), on top of which the toxic A protein resides. A promising strategy to counteract the devastating biological effects of this AB5 protein involves the development of inhibitors that can act as mimics of membrane-bound GM1 molecules, i.e., that can bind CT strongly and selectively. To reach this goal, two features are essential: First of all, the inhibitor should display oligosaccharides that resemble as much as possible the naturally occurring cell-surface pentasaccharide onto which CT normally binds, the so-called GM1 sugar (the oligosaccharide part of which is then labeled GM1os). Second, the inhibitor should be able to bind CT via multivalent interactions so as to bind CT as strongly as possible to allow for a real competition with the cell-membrane-bound GM1 molecules. In this Account, we present elements of the path that leads to strong CT inhibition by outlining the roles of multivalency and the development and use of GM1 mimics. First, multivalency effects were investigated using "sugar-coated" platforms, ranging from dendritic structures with up to eight oligosaccharides to platforms that mimicked the fivefold symmetry of CT itself. The latter goal was reached either via synthetic scaffolds like corannulene or calix[5]arene or via the development of a neolectin CT mimic that itself carries five GM1os groups. Second, the effect of the nature of the oligosaccharide appended to this platform was investigated via the use of oligosaccharides of increasing complexity, from galactose and lactose to the tetrasaccharide GM2os and eventually to GM1os itself. The combination of these threads gives rise to a series of inhibitors that can strongly bind CT, with IC50 values below 100 pM, and in some cases can even bind one-on-one.
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Affiliation(s)
- Han Zuilhof
- Laboratory
of Organic Chemistry, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands
- School
of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
- Department
of Chemical and Materials Engineering, King Abdulaziz University, Jeddah, Saudi Arabia
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Poonthiyil V, Golovko VB, Fairbanks AJ. Size-optimized galactose-capped gold nanoparticles for the colorimetric detection of heat-labile enterotoxin at nanomolar concentrations. Org Biomol Chem 2016; 13:5215-23. [PMID: 25853438 DOI: 10.1039/c5ob00447k] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development of a galactose-capped gold nanoparticle-based colorimetric sensor for the detection of the lectin heat-labile enterotoxin is reported. Heat-labile enterotoxin is one of the pathogenic agents responsible for the intestinal disease called 'traveller's diarrhoea'. By means of specific interaction between galactose moieties attached to the surface of gold nanoparticles and receptors on the B-subunit of heat-labile enterotoxin (LTB), the gold nanoparticles reported here act as an efficient colorimetric sensor, which can detect the toxin at nanomolar concentrations. The effect of gold nanoparticle size on the detection sensitivity was investigated in detail. Amongst the various sizes of gold nanoparticles studied (2, 7, 12, and 20 nm), the 12 nm sized gold nanoparticles were found to be the most efficient, with a minimum heat-labile enterotoxin detection concentration of 100 nM. The red to purple colour change of the gold nanoparticle solution occurred within two minutes, indicating rapid toxin sensing.
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Affiliation(s)
- Vivek Poonthiyil
- Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.
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46
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Müller C, Despras G, Lindhorst TK. Organizing multivalency in carbohydrate recognition. Chem Soc Rev 2016; 45:3275-302. [DOI: 10.1039/c6cs00165c] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Affiliation(s)
- Yoshiko Miura
- Department of Chemical Engineering, Graduate
School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yu Hoshino
- Department of Chemical Engineering, Graduate
School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hirokazu Seto
- Department of Chemical Engineering, Graduate
School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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48
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Marín MJ, Schofield CL, Field RA, Russell DA. Glyconanoparticles for colorimetric bioassays. Analyst 2015; 140:59-70. [PMID: 25277069 DOI: 10.1039/c4an01466a] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Carbohydrate molecules are involved in many of the cellular processes that are important for life. By combining the specific analyte targeting of carbohydrates with the multivalent structure and change of solution colour as a consequence of plasmonic interactions with the aggregation of metal nanoparticles, glyconanoparticles have been used extensively for the development of bioanalytical assays. The noble metals used to create the nanocore, the methodologies used to assemble the carbohydrates on the nanoparticle surface, the carbohydrate chosen for each specific target, the length of the tether that separates the carbohydrate from the nanocore and the density of carbohydrates on the surface all impact on the structural formation of metal based glyconanoparticles. This tutorial review highlights these key components, which directly impact on the selectivity and sensitivity of the developed bioassay, for the colorimetric detection of lectins, toxins and viruses.
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Affiliation(s)
- María J Marín
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, Norfolk NR4 7TJ, UK.
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49
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Brown AC, Koufos E, Balashova NV, Boesze-Battaglia K, Lally ET. Inhibition of LtxA toxicity by blocking cholesterol binding with peptides. Mol Oral Microbiol 2015; 31:94-105. [PMID: 26352738 DOI: 10.1111/omi.12133] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2015] [Indexed: 12/30/2022]
Abstract
The leukotoxin (LtxA) produced by Aggregatibacter actinomycetemcomitans kills host immune cells, allowing the bacterium to establish an ecological niche in the upper aerodigestive tract of its human host. The interaction of LtxA with human immune cells is both complex and multifaceted, involving membrane lipids as well as cell-surface proteins. In the initial encounter with the host cell, LtxA associates with lymphocyte function-associated antigen-1, a cell surface adhesion glycoprotein. However, we have also demonstrated that the toxin associates strongly with the plasma membrane lipids, specifically cholesterol. This association with cholesterol is regulated by a cholesterol recognition amino acid consensus (CRAC) motif, with a sequence of (334) LEEYSKR(340), in the N-terminal region of the toxin. Here, we have demonstrated that removal of cholesterol from the plasma membrane or mutation of the LtxA CRAC motif inhibits the activity of the toxin in THP-1 cells. To inhibit LtxA activity, we designed a short peptide corresponding to the CRAC(336) motif of LtxA (CRAC(336WT)). This peptide binds to cholesterol and thereby inhibits the toxicity of LtxA in THP-1 cells. Previously, we showed that this peptide inhibits LtxA toxicity against Jn.9 (Jurkat) cells, indicating that peptides derived from the cholesterol-binding site of LtxA may have a potential clinical applicability in controlling infections of repeats-in-toxin-producing organisms.
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Affiliation(s)
- A C Brown
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA
| | - E Koufos
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA
| | - N V Balashova
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - K Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - E T Lally
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Krishna Raja M, Ghosh AR, Vino S, Sajitha Lulu S. Analysis and modeling of heat-labile enterotoxins of Escherichia colisuggests a novel space with insights into receptor preference. J Biomol Struct Dyn 2015; 33:1805-18. [DOI: 10.1080/07391102.2014.974073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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