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Liu K, Hunter T, Taverner A, Yin K, MacKay J, Colebrook K, Correia M, Rapp A, Mrsny RJ. GRP75 as a functional element of cholix transcytosis. Tissue Barriers 2023; 11:2039003. [PMID: 35262466 PMCID: PMC9870019 DOI: 10.1080/21688370.2022.2039003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Cholix (Chx) is secreted by non-pandemic strains of Vibrio cholerae in the intestinal lumen. For this exotoxin to induce cell death in non-polarized cells in the intestinal lamina propria, it must traverse the epithelium in the fully intact form. We identified host cell elements in polarized enterocytes associated with Chx endocytosis and apical to basal (A→B) vesicular transcytosis. This pathway overcomes endogenous mechanisms of apical vesicle recycling and lysosomal targeting by interacting with several host cell proteins that include the 75 kDa glucose-regulated protein (GRP75). Apical endocytosis of Chx appears to involve the single membrane spanning protein TMEM132A, and interaction with furin before it engages GRP75 in apical vesicular structures. Sorting within these apical vesicles results in Chx being trafficked to the basal region of cells in association with the Lectin, Mannose Binding 1 protein LMAN1. In this location, Chx interacts with the basement membrane-specific heparan sulfate proteoglycan perlecan in recycling endosomes prior to its release from this basal vesicular compartment to enter the underlying lamina propria. While the furin and LMAN1 elements of this Chx transcytosis pathway undergo cellular redistribution that are reflective of the polarity shifts noted for coatamer complexes COPI and COPII, GRP75 and perlecan fail to show these dramatic rearrangements. Together, these data define essential steps in the A→B transcytosis pathway accessed by Chx to reach the intestinal lamina propria where it can engage and intoxicate certain non-polarized cells.
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Affiliation(s)
- Keyi Liu
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Tom Hunter
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Alistair Taverner
- Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Kevin Yin
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Julia MacKay
- Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Kate Colebrook
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Morgan Correia
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Amandine Rapp
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Randall J. Mrsny
- Applied Molecular Transport, South San Francisco, CA, USA,Department of Pharmacy and Pharmacology, University of Bath, Bath, UK,CONTACT Randall J. Mrsny Applied Molecular Transport, 450 East Jamie Court, South San Francisco, CA94080USA
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2
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McCarthy M, Goncalves M, Powell H, Morey B, Turner M, Merrill AR. A Structural Approach to Anti-Virulence: A Discovery Pipeline. Microorganisms 2021; 9:microorganisms9122514. [PMID: 34946116 PMCID: PMC8704661 DOI: 10.3390/microorganisms9122514] [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: 10/31/2021] [Revised: 11/27/2021] [Accepted: 11/30/2021] [Indexed: 11/25/2022] Open
Abstract
The anti-virulence strategy is designed to prevent bacterial virulence factors produced by pathogenic bacteria from initiating and sustaining an infection. One family of bacterial virulence factors is the mono-ADP-ribosyltransferase toxins, which are produced by pathogens as tools to compromise the target host cell. These toxins are bacterial enzymes that exploit host cellular NAD+ as the donor substrate to modify an essential macromolecule acceptor target in the host cell. This biochemical reaction modifies the target macromolecule (often protein or DNA) and functions in a binary fashion to turn the target activity on or off by blocking or impairing a critical process or pathway in the host. A structural biology approach to the anti-virulence method to neutralize the cytotoxic effect of these factors requires the search and design of small molecules that bind tightly to the enzyme active site and prevent catalytic function essentially disarming the pathogen. This method requires a high-resolution structure to serve as the model for small molecule inhibitor development, which illuminates the path to drug development. This alternative strategy to antibiotic therapy represents a paradigm shift that may circumvent multi-drug resistance in the offending microbe through anti-virulence therapy. In this report, the rationale for the anti-virulence structural approach will be discussed along with recent efforts to apply this method to treat honey bee diseases using natural products.
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3
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Lugo MR, Merrill AR. Development of Anti-Virulence Therapeutics against Mono-ADP-Ribosyltransferase Toxins. Toxins (Basel) 2020; 13:toxins13010016. [PMID: 33375750 PMCID: PMC7824265 DOI: 10.3390/toxins13010016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/16/2020] [Accepted: 12/23/2020] [Indexed: 12/27/2022] Open
Abstract
Mono-ADP-ribosyltransferase toxins are often key virulence factors produced by pathogenic bacteria as tools to compromise the target host cell. These toxins are enzymes that use host cellular NAD+ as the substrate to modify a critical macromolecule target in the host cell machinery. This post-translational modification of the target macromolecule (usually protein or DNA) acts like a switch to turn the target activity on or off resulting in impairment of a critical process or pathway in the host. One approach to stymie bacterial pathogens is to curtail the toxic action of these factors by designing small molecules that bind tightly to the enzyme active site and prevent catalytic function. The inactivation of these toxins/enzymes is targeted for the site of action within the host cell and small molecule therapeutics can function as anti-virulence agents by disarming the pathogen. This represents an alternative strategy to antibiotic therapy with the potential as a paradigm shift that may circumvent multi-drug resistance in the offending microbe. In this review, work that has been accomplished during the past two decades on this approach to develop anti-virulence compounds against mono-ADP-ribosyltransferase toxins will be discussed.
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4
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Ogura K, Yahiro K, Moss J. Cell Death Signaling Pathway Induced by Cholix Toxin, a Cytotoxin and eEF2 ADP-Ribosyltransferase Produced by Vibrio cholerae. Toxins (Basel) 2020; 13:toxins13010012. [PMID: 33374361 PMCID: PMC7824611 DOI: 10.3390/toxins13010012] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/20/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022] Open
Abstract
Pathogenic microorganisms produce various virulence factors, e.g., enzymes, cytotoxins, effectors, which trigger development of pathologies in infectious diseases. Cholera toxin (CT) produced by O1 and O139 serotypes of Vibrio cholerae (V. cholerae) is a major cytotoxin causing severe diarrhea. Cholix cytotoxin (Cholix) was identified as a novel eukaryotic elongation factor 2 (eEF2) adenosine-diphosphate (ADP)-ribosyltransferase produced mainly in non-O1/non-O139 V. cholerae. The function and role of Cholix in infectious disease caused by V. cholerae remain unknown. The crystal structure of Cholix is similar to Pseudomonas exotoxin A (PEA) which is composed of an N-terminal receptor-recognition domain and a C-terminal ADP-ribosyltransferase domain. The endocytosed Cholix catalyzes ADP-ribosylation of eEF2 in host cells and inhibits protein synthesis, resulting in cell death. In a mouse model, Cholix caused lethality with severe liver damage. In this review, we describe the mechanism underlying Cholix-induced cytotoxicity. Cholix-induced apoptosis was regulated by mitogen-activated protein kinase (MAPK) and protein kinase C (PKC) signaling pathways, which dramatically enhanced tumor necrosis factor-α (TNF-α) production in human liver, as well as the amount of epithelial-like HepG2 cancer cells. In contrast, Cholix induced apoptosis in hepatocytes through a mitochondrial-dependent pathway, which was not stimulated by TNF-α. These findings suggest that sensitivity to Cholix depends on the target cell. A substantial amount of information on PEA is provided in order to compare/contrast this well-characterized mono-ADP-ribosyltransferase (mART) with Cholix.
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Affiliation(s)
- Kohei Ogura
- Advanced Health Care Science Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa 920-0942, Japan
- Correspondence: (K.O.); (K.Y.); Tel.: +81-76-265-2590 (K.O.); +81-43-226-2048 (K.Y.)
| | - Kinnosuke Yahiro
- Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan
- Correspondence: (K.O.); (K.Y.); Tel.: +81-76-265-2590 (K.O.); +81-43-226-2048 (K.Y.)
| | - Joel Moss
- Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1590, USA;
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5
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Masuyer G. Crystal Structure of Exotoxin A from Aeromonas Pathogenic Species. Toxins (Basel) 2020; 12:toxins12060397. [PMID: 32549399 PMCID: PMC7354439 DOI: 10.3390/toxins12060397] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 02/07/2023] Open
Abstract
Aeromonas exotoxin A (AE) is a bacterial virulence factor recently discovered in a clinical case of necrotising fasciitis caused by the flesh-eating Aeromonas hydrophila. Here, database mining shows that AE is present in the genome of several emerging Aeromonas pathogenic species. The X-ray crystal structure of AE was solved at 2.3 Å and presents all the hallmarks common to diphthamide-specific mono-ADP-ribosylating toxins, suggesting AE is a fourth member of this family alongside the diphtheria toxin, Pseudomonas exotoxin A and cholix. Structural homology indicates AE may use a similar mechanism of cytotoxicity that targets eukaryotic elongation factor 2 and thus inhibition of protein synthesis. The structure of AE also highlights unique features including a metal binding site, and a negatively charged cleft that could play a role in interdomain interactions and may affect toxicity. This study raises new opportunities to engineer alternative toxin-based molecules with pharmaceutical potential.
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Affiliation(s)
- Geoffrey Masuyer
- Department of Pharmacy and Pharmacology, Centre for Therapeutic Innovation, University of Bath, Bath BA2 7AY, UK
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6
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Taverner A, MacKay J, Laurent F, Hunter T, Liu K, Mangat K, Song L, Seto E, Postlethwaite S, Alam A, Chandalia A, Seung M, Saberi M, Feng W, Mrsny RJ. Cholix protein domain I functions as a carrier element for efficient apical to basal epithelial transcytosis. Tissue Barriers 2020; 8:1710429. [PMID: 31928299 PMCID: PMC7063863 DOI: 10.1080/21688370.2019.1710429] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cholix (Chx) is expressed by the intestinal pathogen Vibrio cholerae as a single chain of 634 amino acids (~70.7 kDa protein) that folds into three distinct domains, with elements of the second and third domains being involved in accessing the cytoplasm of nonpolarized cells and inciting cell death via ADP-ribosylation of elongation factor 2, respectively. In order to reach nonpolarized cells within the intestinal lamina propria, however, Chx must cross the polarized epithelial barrier in an intact form. Here, we provide in vitro and in vivo demonstrations that a nontoxic Chx transports across intestinal epithelium via a vesicular trafficking pathway that rapidly achieves vesicular apical to basal (A→B) transcytosis and avoids routing to lysosomes. Specifically, Chx traffics in apical endocytic Rab7+ vesicles and in basal exocytic Rab11+ vesicles with a transition between these domains occurring in the ER-Golgi intermediate compartment (ERGIC) through interactions with the lectin mannose-binding protein 1 (LMAN1) protein that undergoes an intracellular re-distribution that coincides with the re-organization of COPI+ and COPII+ vesicular structures. Truncation studies demonstrated that domain I of Chx alone was sufficient to efficiently complete A→B transcytosis and capable of ferrying genetically conjoined human growth hormone (hGH). These studies provide evidence for a pathophysiological strategy where native Chx exotoxin secreted in the intestinal lumen by nonpandemic V. cholerae can reach nonpolarized cells within the lamina propria in an intact form by using a nondestructive pathway to cross in the intestinal epithelial that appears useful for oral delivery of biopharmaceuticals.One-Sentence Summary: Elements within the first domain of the Cholix exotoxin protein are essential and sufficient for the apical to basal transcytosis of this Vibrio cholerae-derived virulence factor across polarized intestinal epithelial cells.
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Affiliation(s)
- Alistair Taverner
- Department of Pharmacy and Pharmacology, University of Bath, Bath, England
| | - Julia MacKay
- Department of Pharmacy and Pharmacology, University of Bath, Bath, England
| | - Floriane Laurent
- Department of Pharmacy and Pharmacology, University of Bath, Bath, England
| | - Tom Hunter
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Keyi Liu
- Applied Molecular Transport, South San Francisco, CA, USA
| | | | - Lisa Song
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Elbert Seto
- Applied Molecular Transport, South San Francisco, CA, USA
| | | | - Aatif Alam
- Applied Molecular Transport, South San Francisco, CA, USA
| | | | - Minji Seung
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Mazi Saberi
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Weijun Feng
- Applied Molecular Transport, South San Francisco, CA, USA
| | - Randall J Mrsny
- Department of Pharmacy and Pharmacology, University of Bath, Bath, England.,Applied Molecular Transport, South San Francisco, CA, USA
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7
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Feldmann J, Li Y, Tor Y. Emissive Synthetic Cofactors: A Highly Responsive NAD + Analogue Reveals Biomolecular Recognition Features. Chemistry 2019; 25:4379-4389. [PMID: 30648291 DOI: 10.1002/chem.201805520] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Indexed: 12/14/2022]
Abstract
Apart from its vital function as a redox cofactor, nicotinamide adenine dinucleotide (NAD+ ) has emerged as a crucial substrate for NAD+ -consuming enzymes, including poly(ADP-ribosyl)transferase 1 (PARP1) and CD38/CD157. Their association with severe diseases, such as cancer, Alzheimer's disease, and depressions, necessitates the development of new analytical tools based on traceable NAD+ surrogates. Here, the synthesis, photophysics and biochemical utilization of an emissive, thieno[3,4-d]pyrimidine-based NAD+ surrogate, termed Nth AD+ , are described. Its preparation was accomplished by enzymatic conversion of synthetic th ATP by nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1). The new NAD+ analogue possesses useful photophysical features including redshifted absorption and emission maxima as well as a relatively high quantum yield. Serving as a versatile substrate, Nth AD+ was reduced by alcohol dehydrogenase (ADH) to Nth ADH and afforded th ADP-ribose (th ADPr) upon hydrolysis by NAD+ -nucleosidase (NADase). Furthermore, Nth AD+ was engaged in cholera toxin A (CTA)-catalyzed mono(th ADP-ribosyl)ation, but was found incapable in promoting PARP1-mediated poly(th ADP-ribosyl)ation. Due to its high photophysical responsiveness, Nth AD+ is suited for spectroscopic real-time monitoring. Intriguingly, and as an N7-lacking NAD+ surrogate, the thieno-based cofactor showed reduced compatibility (i.e., functional similarity compared to native NAD+ ) relative to its isothiazolo-based analogue. The distinct tolerance, displayed by diverse NAD+ producing and consuming enzymes, suggests unique biological recognition features and dependency on the purine N7 moiety, which is found to be of importance, if not essential, for PARP1-mediated reactions.
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Affiliation(s)
- Jonas Feldmann
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA.,Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377, Munich, Germany
| | - Yao Li
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Yitzhak Tor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
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8
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Characterization of the catalytic signature of Scabin toxin, a DNA-targeting ADP-ribosyltransferase. Biochem J 2018; 475:225-245. [PMID: 29208763 DOI: 10.1042/bcj20170818] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/30/2017] [Accepted: 12/04/2017] [Indexed: 01/27/2023]
Abstract
Scabin was previously identified as a novel DNA-targeting mono-ADP-ribosyltransferase (mART) toxin from the plant pathogen 87.22 strain of Streptomyces scabies Scabin is a member of the Pierisin-like subgroup of mART toxins, since it targets DNA. An in-depth characterization of both the glycohydrolase and transferase enzymatic activities of Scabin was conducted. Several protein variants were developed based on an initial Scabin·DNA molecular model. Consequently, three residues were deemed important for DNA-binding and transferase activity. Trp128 and Trp155 are important for binding the DNA substrate and participate in the reaction mechanism, whereas Tyr129 was shown to be important only for DNA binding, but was not involved in the reaction mechanism. Trp128 and Trp155 are both conserved within the Pierisin-like toxins, whereas Tyr129 is a unique substitution within the group. Scabin showed substrate specificity toward double-stranded DNA containing a single-base overhang, as a model for single-stranded nicked DNA. The crystal structure of Scabin bound to NADH - a competitive inhibitor of Scabin - was determined, providing important insights into the active-site structure and Michaelis-Menten complex of the enzyme. Based on these results, a novel DNA-binding motif is proposed for Scabin with substrate and the key residues that may participate in the Scabin·NAD(+) complex are highlighted.
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9
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Lüscher B, Bütepage M, Eckei L, Krieg S, Verheugd P, Shilton BH. ADP-Ribosylation, a Multifaceted Posttranslational Modification Involved in the Control of Cell Physiology in Health and Disease. Chem Rev 2017; 118:1092-1136. [PMID: 29172462 DOI: 10.1021/acs.chemrev.7b00122] [Citation(s) in RCA: 172] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Posttranslational modifications (PTMs) regulate protein functions and interactions. ADP-ribosylation is a PTM, in which ADP-ribosyltransferases use nicotinamide adenine dinucleotide (NAD+) to modify target proteins with ADP-ribose. This modification can occur as mono- or poly-ADP-ribosylation. The latter involves the synthesis of long ADP-ribose chains that have specific properties due to the nature of the polymer. ADP-Ribosylation is reversed by hydrolases that cleave the glycosidic bonds either between ADP-ribose units or between the protein proximal ADP-ribose and a given amino acid side chain. Here we discuss the properties of the different enzymes associated with ADP-ribosylation and the consequences of this PTM on substrates. Furthermore, the different domains that interpret either mono- or poly-ADP-ribosylation and the implications for cellular processes are described.
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Affiliation(s)
- Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University , 52057 Aachen, Germany
| | - Mareike Bütepage
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University , 52057 Aachen, Germany
| | - Laura Eckei
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University , 52057 Aachen, Germany
| | - Sarah Krieg
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University , 52057 Aachen, Germany
| | - Patricia Verheugd
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University , 52057 Aachen, Germany
| | - Brian H Shilton
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University , 52057 Aachen, Germany.,Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario , Medical Sciences Building Room 332, London, Ontario Canada N6A 5C1
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10
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Saenz-Méndez P, Eriksson M, Eriksson LA. Ligand Selectivity between the ADP-Ribosylating Toxins: An Inverse-Docking Study for Multitarget Drug Discovery. ACS OMEGA 2017; 2:1710-1719. [PMID: 30023642 PMCID: PMC6044789 DOI: 10.1021/acsomega.7b00010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/17/2017] [Indexed: 06/02/2023]
Abstract
Bacterial adenosine 5'-diphosphate-ribosylating toxins are encoded by several human pathogens, such as Pseudomonas aeruginosa (exotoxin A (ETA)), Corynebacterium diphtheriae (diphtheria toxin (DT)), and Vibrio cholerae (cholix toxin (CT)). The toxins modify eukaryotic elongation factor 2, an essential human enzyme in protein synthesis, thereby causing cell death. Targeting external virulence factors, such as the above toxins, is a promising alternative for developing new antibiotics, while at the same time avoiding drug resistance. This study aims to establish a reliable computational methodology to find a "silver bullet" able to target all three toxins. Herein, we have undertaken a detailed analysis of the active sites of ETA, DT, and CT, followed by the determination of the most appropriate selection of the size of the docking sphere. Thereafter, we tested two different approaches for normalizing the docking scores and used these to verify the best target (toxin) for each ligand. The results indicate that the methodology is suitable for identifying selective as well as multitoxin inhibitors, further validating the robustness of inverse docking for target-fishing experiments.
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Affiliation(s)
- Patricia Saenz-Méndez
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 405 30 Göteborg, Sweden
- Computational
Chemistry and Biology Group, Facultad de Química, Universidad de la República, 11800 Montevideo, Uruguay
| | - Martin Eriksson
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 405 30 Göteborg, Sweden
| | - Leif A. Eriksson
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, 405 30 Göteborg, Sweden
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11
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Ravulapalli R, Lugo MR, Pfoh R, Visschedyk D, Poole A, Fieldhouse RJ, Pai EF, Merrill AR. Characterization of Vis Toxin, a Novel ADP-Ribosyltransferase from Vibrio splendidus. Biochemistry 2015; 54:5920-36. [PMID: 26352925 DOI: 10.1021/acs.biochem.5b00921] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vis toxin was identified by a bioinformatics strategy as a putative virulence factor produced by Vibrio splendidus with mono-ADP-ribosyltransferase activity. Vis was purified to homogeneity as a 28 kDa single-domain enzyme and was shown to possess NAD(+)-glycohydrolase [KM(NAD(+)) = 276 ± 12 μM] activity and with an R-S-E-X-E motif; it targets arginine-related compounds [KM(agmatine) = 272 ± 18 mM]. Mass spectrometry analysis revealed that Vis labels l-arginine with ADP-ribose from the NAD(+) substrate at the amino nitrogen of the guanidinium side chain. Vis is toxic to yeast when expressed in the cytoplasm under control of the CUP1 promotor, and catalytic variants lost the ability to kill the yeast host, indicating that the toxin exerts its lethality through its enzyme activity. Several small molecule inhibitors were identified from a virtual screen, and the most potent compounds were found to inhibit the transferase activity of the enzyme with Ki values ranging from 25 to 134 μM. Inhibitor compound M6 bears the necessary attributes of a solid candidate as a lead compound for therapeutic development. Vis toxin was crystallized, and the structures of the apoenzyme (1.4 Å) and the enzyme bound with NAD(+) (1.8 Å) and with the M6 inhibitor (1.5 Å) were determined. The structures revealed that Vis represents a new subgroup within the mono-ADP-ribosyltransferase toxin family.
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Affiliation(s)
- Ravikiran Ravulapalli
- Department of Molecular and Cellular Biology, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - Miguel R Lugo
- Department of Molecular and Cellular Biology, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - Roland Pfoh
- Department of Biology, York University , Toronto, ON, Canada M3J 1P3.,Department of Biochemistry, University of Toronto , Toronto, ON, Canada M5S 1A8.,Campbell Family Institute for Cancer Research, Princess Margaret Hospital , Toronto, ON, Canada M5G 1L7
| | - Danielle Visschedyk
- Department of Molecular and Cellular Biology, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - Amanda Poole
- Department of Molecular and Cellular Biology, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - Robert J Fieldhouse
- Computational Biology Center, Memorial Sloan-Kettering Cancer Center , New York, New York 10065, United States.,Department of Systems Biology, Harvard Medical School , Boston, Massachusetts 02115, United States
| | - Emil F Pai
- Department of Biochemistry, University of Toronto , Toronto, ON, Canada M5S 1A8.,Campbell Family Institute for Cancer Research, Princess Margaret Hospital , Toronto, ON, Canada M5G 1L7.,Departments of Medical Biophysics and Molecular Genetics, University of Toronto , Toronto, ON, Canada M5S 1A8
| | - A Rod Merrill
- Department of Molecular and Cellular Biology, University of Guelph , Guelph, Ontario, Canada N1G 2W1
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12
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Lugo MR, Merrill AR. The Father, Son and Cholix Toxin: The Third Member of the DT Group Mono-ADP-Ribosyltransferase Toxin Family. Toxins (Basel) 2015. [PMID: 26213968 PMCID: PMC4549722 DOI: 10.3390/toxins7082757] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The cholix toxin gene (chxA) was first identified in V. cholerae strains in 2007, and the protein was identified by bioinformatics analysis in 2008. It was identified as the third member of the diphtheria toxin group of mono-ADP-ribosyltransferase toxins along with P. aeruginosa exotoxin A and C. diphtheriae diphtheria toxin. Our group determined the structure of the full-length, three-domain cholix toxin at 2.1 Å and its C-terminal catalytic domain (cholixc) at 1.25 Å resolution. We showed that cholix toxin is specific for elongation factor 2 (diphthamide residue), similar to exotoxin A and diphtheria toxin. Cholix toxin possesses molecular features required for infection of eukaryotes by receptor-mediated endocytosis, translocation to the host cytoplasm and inhibition of protein synthesis. More recently, we also solved the structure of full-length cholix toxin in complex with NAD+ and proposed a new kinetic model for cholix enzyme activity. In addition, we have taken a computational approach that revealed some important properties of the NAD+-binding pocket at the residue level, including the role of crystallographic water molecules in the NAD+ substrate interaction. We developed a pharmacophore model of cholix toxin, which revealed a cationic feature in the side chain of cholix toxin active-site inhibitors that may determine the active pose. Notably, several recent reports have been published on the role of cholix toxin as a major virulence factor in V. cholerae (non-O1/O139 strains). Additionally, FitzGerald and coworkers prepared an immunotoxin constructed from domains II and III as a cancer treatment strategy to complement successful immunotoxins derived from P. aeruginosa exotoxin A.
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Affiliation(s)
- Miguel R Lugo
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - A Rod Merrill
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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13
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López-Hernández KM, Pardío-Sedas V, Lizárraga-Partida L, Williams JDJ, Martínez-Herrera D, Flores-Primo A, Uscanga-Serrano R. Seasonal abundance of Vibrio cholerae non O1/non O139 chxA+ in oysters harvested in a coastal lagoon of Mexico's Gulf coast: A seafood safety risk concern. Food Control 2015. [DOI: 10.1016/j.foodcont.2015.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lugo MR, Merrill AR. A comparative structure-function analysis of active-site inhibitors of Vibrio cholerae cholix toxin. J Mol Recognit 2015; 28:539-52. [PMID: 25756608 DOI: 10.1002/jmr.2469] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 01/26/2015] [Accepted: 01/27/2015] [Indexed: 01/27/2023]
Abstract
Cholix toxin from Vibrio cholerae is a novel mono-ADP-ribosyltransferase (mART) toxin that shares structural and functional properties with Pseudomonas aeruginosa exotoxin A and Corynebacterium diphtheriae diphtheria toxin. Herein, we have used the high-resolution X-ray structure of full-length cholix toxin in the apo form, NAD(+) bound, and 10 structures of the cholix catalytic domain (C-domain) complexed with several strong inhibitors of toxin enzyme activity (NAP, PJ34, and the P-series) to study the binding mode of the ligands. A pharmacophore model based on the active pose of NAD(+) was compared with the active conformation of the inhibitors, which revealed a cationic feature in the side chain of the inhibitors that may determine the active pose. Moreover, a conformational search was conducted for the missing coordinates of one of the main active-site loops (R-loop). The resulting structural models were used to evaluate the interaction energies and for 3D-QSAR modeling. Implications for a rational drug design approach for mART toxins were derived.
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Affiliation(s)
- Miguel R Lugo
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - A Rod Merrill
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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Lugo MR, Merrill AR. Pocket analysis of the full-length cholix toxin. An assessment of the structure-dynamics of the apo catalytic domain. J Biomol Struct Dyn 2015; 33:2452-68. [PMID: 25559625 DOI: 10.1080/07391102.2014.1000972] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cholix toxin from Vibrio cholerae is the third member of the diphtheria toxin (DT) group of mono-ADP-ribosyltransferase (mART) bacterial toxins. It shares structural and functional properties with Pseudomonas aeruginosa exotoxin A and Corynebacterium diphtheriae DT. Cholix toxin is an important model for the development of antivirulence approaches and therapeutics against these toxins from pathogenic bacteria. Herein, we have used the high-resolution X-ray structure of full-length cholix complexed with NAD(+) to describe the properties of the NAD(+)-binding pocket at the residue level, including the role of crystallographic water molecules in the NAD(+) substrate interaction. The full-length apo cholix structure is used to describe the putative NAD(+)-binding site(s) and to correlate biochemical with crystallographic data to study the stoichiometry and orientation of bound NAD(+) molecules. We quantitatively describe the NAD(+) substrate interactions on a residue basis for the main 22 pocket residues in cholixf, a glycerol and 5 contact water molecules as part of the recognition surface by the substrate according to the conditions of crystallization. In addition, the dynamic properties of an in silico version of the catalytic domain were investigated in order to understand the lack of electronic density for one of the main flexible loops (R-loop) in the pocket of X-ray complexes. Implications for a rational drug design approach for mART toxins are derived.
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Affiliation(s)
- Miguel R Lugo
- a Department of Molecular and Cellular Biology, Science Complex , University of Guelph , Guelph , ON , Canada N1G2W
| | - A Rod Merrill
- a Department of Molecular and Cellular Biology, Science Complex , University of Guelph , Guelph , ON , Canada N1G2W
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Krska D, Ravulapalli R, Fieldhouse RJ, Lugo MR, Merrill AR. C3larvin toxin, an ADP-ribosyltransferase from Paenibacillus larvae. J Biol Chem 2014; 290:1639-53. [PMID: 25477523 DOI: 10.1074/jbc.m114.589846] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
C3larvin toxin was identified by a bioinformatic strategy as a putative mono-ADP-ribosyltransferase and a possible virulence factor from Paenibacillus larvae, which is the causative agent of American Foulbrood in honey bees. C3larvin targets RhoA as a substrate for its transferase reaction, and kinetics for both the NAD(+) (Km = 34 ± 12 μm) and RhoA (Km = 17 ± 3 μm) substrates were characterized for this enzyme from the mono-ADP-ribosyltransferase C3 toxin subgroup. C3larvin is toxic to yeast when expressed in the cytoplasm, and catalytic variants of the enzyme lost the ability to kill the yeast host, indicating that the toxin exerts its lethality through its enzyme activity. A small molecule inhibitor of C3larvin enzymatic activity was discovered called M3 (Ki = 11 ± 2 μm), and to our knowledge, is the first inhibitor of transferase activity of the C3 toxin family. C3larvin was crystallized, and its crystal structure (apoenzyme) was solved to 2.3 Å resolution. C3larvin was also shown to have a different mechanism of cell entry from other C3 toxins.
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Affiliation(s)
- Daniel Krska
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Ravikiran Ravulapalli
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Robert J Fieldhouse
- the Computational Biology Center, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, and the Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Miguel R Lugo
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - A Rod Merrill
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada,
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Simon NC, Aktories K, Barbieri JT. Novel bacterial ADP-ribosylating toxins: structure and function. Nat Rev Microbiol 2014; 12:599-611. [PMID: 25023120 PMCID: PMC5846498 DOI: 10.1038/nrmicro3310] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacterial ADP-ribosyltransferase toxins (bARTTs) transfer ADP-ribose to eukaryotic proteins to promote bacterial pathogenesis. In this Review, we use prototype bARTTs, such as diphtheria toxin and pertussis toxin, as references for the characterization of several new bARTTs from human, insect and plant pathogens, which were recently identified by bioinformatic analyses. Several of these toxins, including cholix toxin (ChxA) from Vibrio cholerae, SpyA from Streptococcus pyogenes, HopU1 from Pseudomonas syringae and the Tcc toxins from Photorhabdus luminescens, ADP-ribosylate novel substrates and have unique organizations, which distinguish them from the reference toxins. The characterization of these toxins increases our appreciation of the range of structural and functional properties that are possessed by bARTTs and their roles in bacterial pathogenesis.
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Affiliation(s)
- Nathan C. Simon
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI, USA
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology; Albert-Ludwigs-University Freiburg; Freiburg, Germany
| | - Joseph T. Barbieri
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI, USA
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Structural biology of the writers, readers, and erasers in mono- and poly(ADP-ribose) mediated signaling. Mol Aspects Med 2013; 34:1088-108. [PMID: 23458732 PMCID: PMC3726583 DOI: 10.1016/j.mam.2013.02.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 02/01/2013] [Accepted: 02/18/2013] [Indexed: 12/19/2022]
Abstract
ADP-ribosylation of proteins regulates protein activities in various processes including transcription control, chromatin organization, organelle assembly, protein degradation, and DNA repair. Modulating the proteins involved in the metabolism of ADP-ribosylation can have therapeutic benefits in various disease states. Protein crystal structures can help understand the biological functions, facilitate detailed analysis of single residues, as well as provide a basis for development of small molecule effectors. Here we review recent advances in our understanding of the structural biology of the writers, readers, and erasers of ADP-ribosylation.
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