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Fellows AL, Chen CN, Xie C, Iyer N, Schmidt L, Yin X, Yates LA, Mayr M, Cowburn A, Zhao L, Wojciak-Stothard B. ARF6 as a Novel Activator of HIF-2α in Pulmonary Arterial Hypertension. Am J Respir Cell Mol Biol 2025; 72:380-392. [PMID: 39556110 PMCID: PMC12005040 DOI: 10.1165/rcmb.2024-0149oc] [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: 03/28/2024] [Accepted: 11/18/2024] [Indexed: 11/19/2024] Open
Abstract
ARF6 (ADP-ribosylation factor 6), a GTPase associated with cancer metastasis, is activated in the lung endothelium in pulmonary arterial hypertension (PAH). To identify ARF6-regulated pathways relevant to PAH, we performed a state-of-the-art proteomic analysis of human pulmonary artery endothelial cells (HPAECs) overexpressing the wild-type, constitutively active, fast-cycling, and dominant-negative mutants of ARF6. The analysis revealed a novel link of ARF6 with HIF (hypoxia-inducible factor), in addition to endocytotic vesicle trafficking, cell proliferation, angiogenesis, oxidative stress, and lipid metabolism. Active ARF6 markedly increased expression and activity of HIF-2, critical in PAH, with HIF-1 relatively unaffected. Hypoxic ARF6 activation was a prerequisite for HIF-2 activation and HIF-dependent gene expression in HPAECs, PAH blood-derived late-outgrowth endothelial colony-forming cells, and hypoxic mouse lungs in vivo. A novel ARF6 inhibitor, chlortetracycline (CTC), reduced hypoxia-induced HIF-2 activation, proliferation, and angiogenesis in HPAECs and reduced HIF-2 expression in lung and heart tissues of hypoxic mice. PAH endothelial colony-forming cells showed elevated expression and activity of ARF6 and HIF2, which was attenuated by CTC, and oral CTC attenuated development of pulmonary hypertension in chronically hypoxic mice. We identify EGFR (epidermal growth factor receptor) as a direct interactor of ARF6 and EGFR signaling as a crucial mechanism linking ARF6 and HIF activation. In conclusion, we are the first to demonstrate a key role of ARF6 in the regulation of HIF-2α activation in vitro and in vivo and show that HIF-2α, a master regulator of vascular remodeling in PAH, can be targeted by a clinically approved antibiotic CTC.
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Affiliation(s)
| | | | | | | | - Lukas Schmidt
- King’s British Heart Foundation Centre, King’s College London, London, United Kingdom; and
| | | | - Luke A. Yates
- Department of Infectious Disease, Imperial College London, London, United Kingdom
- Francis Crick Institute, London, United Kingdom
| | | | | | - Lan Zhao
- National Heart and Lung Institute and
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2
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Wenli Y, Wei W, Yubiao P, Hua H, Hongyan T. ARF3 as a novel biomarker and target in acute myeloid leukemia: Insights from pan-cancer analysis. Genomics 2025; 117:110984. [PMID: 39756487 DOI: 10.1016/j.ygeno.2024.110984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2024] [Revised: 12/08/2024] [Accepted: 12/20/2024] [Indexed: 01/07/2025]
Abstract
Acute myeloid leukemia is a malignant hematologic disorder characterized by the excessive proliferation and accumulation of immature myeloid cells. This abnormality disrupts normal hematopoiesis, leading to symptoms such as anemia, increased susceptibility to infections and bleeding. ADP-ribosylation factors (ARFs) are critical in various cellular functions, including vesicular trafficking, membrane dynamics, cytoskeleton organization, signal transduction, endocytosis, exocytosis, and maintaining organelle integrity. Among ARF family members, ARF3 has garnered relatively less attention compared to other members like ARF1 and ARF6, leaving its role less understood. In this study, we found that the higher expression of ARF3 is correlated with poorer prognosis in AML patients. Silencing ARF3 in AML cells interrupted cell cycle progression and promote cell death as well as inhibit leukemogenesis in vivo. Mechanically, ARF3 knockdown suppressed AML progression by inhibiting PI3K/Akt signaling pathway. Our results indicate that ARF3 is linked to poor outcomes in AML patients and can serve as a potential therapeutic target for AML treatment.
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Affiliation(s)
- Yang Wenli
- Department of Hematology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Key Laboratory of Hematopoietic Malignancy, Zhejiang University, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Clinical Research Center For Hematological Disorder, Hangzhou, Zhejiang, PR China; Zhejiang University Cancer Center, Hangzhou, Zhejiang, PR China
| | - Wang Wei
- Department of Hematology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Key Laboratory of Hematopoietic Malignancy, Zhejiang University, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Clinical Research Center For Hematological Disorder, Hangzhou, Zhejiang, PR China; Zhejiang University Cancer Center, Hangzhou, Zhejiang, PR China
| | - Pan Yubiao
- Department of Hematology, Zhejiang Hospital, Zhejiang, PR China
| | - Huang Hua
- Department of Hematology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Key Laboratory of Hematopoietic Malignancy, Zhejiang University, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Clinical Research Center For Hematological Disorder, Hangzhou, Zhejiang, PR China; Zhejiang University Cancer Center, Hangzhou, Zhejiang, PR China
| | - Tong Hongyan
- Department of Hematology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Key Laboratory of Hematopoietic Malignancy, Zhejiang University, Hangzhou, Zhejiang, PR China; Zhejiang Provincial Clinical Research Center For Hematological Disorder, Hangzhou, Zhejiang, PR China; Zhejiang University Cancer Center, Hangzhou, Zhejiang, PR China.
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3
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Machin DC, Williamson DJ, Fisher P, Miller VJ, Arnott ZLP, Stevenson CME, Wildsmith GC, Ross JF, Wasson CW, Macdonald A, Andrews BI, Ungar D, Turnbull WB, Webb ME. Sortase-Modified Cholera Toxoids Show Specific Golgi Localization. Toxins (Basel) 2024; 16:194. [PMID: 38668619 PMCID: PMC11054894 DOI: 10.3390/toxins16040194] [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: 02/08/2024] [Revised: 03/18/2024] [Accepted: 04/09/2024] [Indexed: 04/29/2024] Open
Abstract
Cholera toxoid is an established tool for use in cellular tracing in neuroscience and cell biology. We use a sortase labeling approach to generate site-specific N-terminally modified variants of both the A2-B5 heterohexamer and B5 pentamer forms of the toxoid. Both forms of the toxoid are endocytosed by GM1-positive mammalian cells, and while the heterohexameric toxoid was principally localized in the ER, the B5 pentamer showed an unexpectedly specific localization in the medial/trans-Golgi. This study suggests a future role for specifically labeled cholera toxoids in live-cell imaging beyond their current applications in neuronal tracing and labeling of lipid rafts in fixed cells.
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Affiliation(s)
- Darren C. Machin
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - Daniel J. Williamson
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - Peter Fisher
- Department of Biology, University of York, York YO10 5DD, UK
| | | | - Zoe L. P. Arnott
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - Charlotte M. E. Stevenson
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - Gemma C. Wildsmith
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - James F. Ross
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - Christopher W. Wasson
- Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK (A.M.)
| | - Andrew Macdonald
- Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK (A.M.)
| | - Benjamin I. Andrews
- GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - Daniel Ungar
- Department of Biology, University of York, York YO10 5DD, UK
| | - W. Bruce Turnbull
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
| | - Michael E. Webb
- School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; (D.C.M.)
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4
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Sun D, Guo Y, Tang P, Li H, Chen L. Arf6 as a therapeutic target: Structure, mechanism, and inhibitors. Acta Pharm Sin B 2023; 13:4089-4104. [PMID: 37799386 PMCID: PMC10547916 DOI: 10.1016/j.apsb.2023.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/28/2023] [Accepted: 06/02/2023] [Indexed: 10/07/2023] Open
Abstract
ADP-ribosylation factor 6 (Arf6), a small G-protein of the Ras superfamily, plays pivotal roles in multiple cellular events, including exocytosis, endocytosis, actin remodeling, plasma membrane reorganization and vesicular transport. Arf6 regulates the progression of cancer through the activation of cell motility and invasion. Aberrant Arf6 activation is a potential therapeutic target. This review aims to understand the comprehensive function of Arf6 for future cancer therapy. The Arf6 GEFs, protein structure, and roles in cancer have been summarized. Comprehending the mechanism underlying Arf6-mediated cancer cell growth and survival is essential. The structural features of Arf6 and its efforts are discussed and may be contributed to the discovery of future novel protein-protein interaction inhibitors. In addition, Arf6 inhibitors and mechanism of action are listed in the table. This review further emphasizes the crucial roles in drug resistance and attempts to offer an outlook of Arf6 in cancer therapy.
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Affiliation(s)
- Dejuan Sun
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Yuanyuan Guo
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Piyu Tang
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Hua Li
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
- College of Pharmacy, Fujian University of Traditional Chinese Medicine, Fuzhou 350122, China
| | - Lixia Chen
- Wuya College of Innovation, Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
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5
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White C, Bader C, Teter K. The manipulation of cell signaling and host cell biology by cholera toxin. Cell Signal 2022; 100:110489. [PMID: 36216164 PMCID: PMC10082135 DOI: 10.1016/j.cellsig.2022.110489] [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: 09/11/2022] [Accepted: 10/01/2022] [Indexed: 11/03/2022]
Abstract
Vibrio cholerae colonizes the small intestine and releases cholera toxin into the extracellular space. The toxin binds to the apical surface of the epithelium, is internalized into the host endomembrane system, and escapes into the cytosol where it activates the stimulatory alpha subunit of the heterotrimeric G protein by ADP-ribosylation. This initiates a cAMP-dependent signaling pathway that stimulates chloride efflux into the gut, with diarrhea resulting from the accompanying osmotic movement of water into the intestinal lumen. G protein signaling is not the only host system manipulated by cholera toxin, however. Other cellular mechanisms and signaling pathways active in the intoxication process include endocytosis through lipid rafts, retrograde transport to the endoplasmic reticulum, the endoplasmic reticulum-associated degradation system for protein delivery to the cytosol, the unfolded protein response, and G protein de-activation through degradation or the function of ADP-ribosyl hydrolases. Although toxin-induced chloride efflux is thought to be an irreversible event, alterations to these processes could facilitate cellular recovery from intoxication. This review will highlight how cholera toxin exploits signaling pathways and other cell biology events to elicit a diarrheal response from the host.
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Affiliation(s)
- Christopher White
- Burnett School of Biomedical Sciences, 12722 Research Parkway, University of Central Florida, Orlando, FL 32826, USA.
| | - Carly Bader
- Burnett School of Biomedical Sciences, 12722 Research Parkway, University of Central Florida, Orlando, FL 32826, USA.
| | - Ken Teter
- Burnett School of Biomedical Sciences, 12722 Research Parkway, University of Central Florida, Orlando, FL 32826, USA.
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6
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Hespen CW, Zhao X, Hang HC. Membrane targeting enhances muramyl dipeptide binding to NOD2 and Arf6-GTPase in mammalian cells. Chem Commun (Camb) 2022; 58:6598-6601. [PMID: 35584401 DOI: 10.1039/d2cc01903e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
To further understand the mechanisms of muramyl dipeptide (MDP) sensing by NOD2, we evaluated key properties involved in the formation of the Arf6-MDP-NOD2 complex in mammalian cells. We found that the conserved Arf aromatic triad is crucial for binding to MDP-NOD2. Mutation of Arf6 N-myristoylation and NOD2 S-palmitoylation also abrogated the formation of the Arf6-MDP-NOD2 complex. Notably, lipid-modified MDP (L18-MDP) increased Arf6-NOD2 assembly. Our results indicate recruitment of Arf6 may explain enhanced activity of lipidated MDP analogues and membrane targeting may be important in developing next-generation NOD2 agonists.
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Affiliation(s)
- Charles W Hespen
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, 1230 York Ave, New York, NY 10065, USA.
| | - Xiaohui Zhao
- Department of Immunology and Microbiology and Department of Chemistry, Scripps Research, 10550 N Torrey Pines Rd, La Jolla, CA 92037, USA
| | - Howard C Hang
- Department of Immunology and Microbiology and Department of Chemistry, Scripps Research, 10550 N Torrey Pines Rd, La Jolla, CA 92037, USA
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7
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Matching protein surface structural patches for high-resolution blind peptide docking. Proc Natl Acad Sci U S A 2022; 119:e2121153119. [PMID: 35482919 PMCID: PMC9170164 DOI: 10.1073/pnas.2121153119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Modeling interactions between short peptides and their receptors is a challenging docking problem due to the peptide flexibility, resulting in a formidable sampling problem of peptide conformation in addition to its orientation. Alternatively, the peptide can be viewed as a piece that complements the receptor monomer structure. Here, we show that the peptide conformation can be determined based on the receptor backbone only and sampled using local structural motifs found in solved protein monomers and interfaces, independent of sequence similarity. This approach outperforms current peptide docking protocols and promotes new directions for peptide interface design. Peptide docking can be perceived as a subproblem of protein–protein docking. However, due to the short length and flexible nature of peptides, many do not adopt one defined conformation prior to binding. Therefore, to tackle a peptide docking problem, not only the relative orientation, but also the bound conformation of the peptide needs to be modeled. Traditional peptide-centered approaches use information about peptide sequences to generate representative conformer ensembles, which can then be rigid-body docked to the receptor. Alternatively, one may look at this problem from the viewpoint of the receptor, namely, that the protein surface defines the peptide-bound conformation. Here, we present PatchMAN (Patch-Motif AligNments), a global peptide-docking approach that uses structural motifs to map the receptor surface with backbone scaffolds extracted from protein structures. On a nonredundant set of protein–peptide complexes, starting from free receptor structures, PatchMAN successfully models and identifies near-native peptide–protein complexes in 58%/84% within 2.5 Å/5 Å interface backbone RMSD, with corresponding sampling in 81%/100% of the cases, outperforming other approaches. PatchMAN leverages the observation that structural units of peptides with their binding pocket can be found not only within interfaces, but also within monomers. We show that the bound peptide conformation is sampled based on the structural context of the receptor only, without taking into account any sequence information. Beyond peptide docking, this approach opens exciting new avenues to study principles of peptide–protein association, and to the design of new peptide binders. PatchMAN is available as a server at https://furmanlab.cs.huji.ac.il/patchman/.
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8
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Sakari M, Tran MT, Rossjohn J, Pulliainen AT, Beddoe T, Littler DR. Crystal structures of pertussis toxin with NAD+ and analogs provide structural insights into the mechanism of its cytosolic ADP-ribosylation activity. J Biol Chem 2022; 298:101892. [PMID: 35378130 PMCID: PMC9079181 DOI: 10.1016/j.jbc.2022.101892] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 11/19/2022] Open
Abstract
Bordetella pertussis is the causative agent of whooping cough, a highly contagious respiratory disease. Pertussis toxin (PT), a major virulence factor secreted by B. pertussis, is an AB5-type protein complex topologically related to cholera toxin. The PT protein complex is internalized by host cells and follows a retrograde trafficking route to the endoplasmic reticulum, where it subsequently dissociates. The released enzymatic S1 subunit is then translocated from the endoplasmic reticulum into the cytosol and subsequently ADP-ribosylates the inhibitory alpha-subunits (Gαi) of heterotrimeric G proteins, thus promoting dysregulation of G protein–coupled receptor signaling. However, the mechanistic details of the ADP-ribosylation activity of PT are not well understood. Here, we describe crystal structures of the S1 subunit in complex with nicotinamide adenine dinucleotide (NAD+), with NAD+ hydrolysis products ADP-ribose and nicotinamide, with NAD+ analog PJ34, and with a novel NAD+ analog formed upon S1 subunit crystallization with 3-amino benzamide and NAD+, which we name benzamide amino adenine dinucleotide. These crystal structures provide unprecedented insights into pre- and post-NAD+ hydrolysis steps of the ADP-ribosyltransferase activity of PT. We propose that these data may aid in rational drug design approaches and further development of PT-specific small-molecule inhibitors.
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Affiliation(s)
- Moona Sakari
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Turku, Finland
| | - Mai T Tran
- Infection and Immunity Program & Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Jamie Rossjohn
- Infection and Immunity Program & Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia; Institute of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff, Wales, United Kingdom
| | - Arto T Pulliainen
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Turku, Finland.
| | - Travis Beddoe
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience, La Trobe University, Bundoora, Victoria, Australia.
| | - Dene R Littler
- Infection and Immunity Program & Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
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Xu Y, Cheng S, Zeng H, Zhou P, Ma Y, Li L, Liu X, Shao F, Ding J. ARF GTPases activate Salmonella effector SopF to ADP-ribosylate host V-ATPase and inhibit endomembrane damage-induced autophagy. Nat Struct Mol Biol 2022; 29:67-77. [PMID: 35046574 DOI: 10.1038/s41594-021-00710-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 12/02/2021] [Indexed: 12/19/2022]
Abstract
Selective autophagy helps eukaryotes to cope with endogenous dangers or foreign invaders; its initiation often involves membrane damage. By studying a Salmonella effector SopF, we recently identified the vacuolar ATPase (V-ATPase)-ATG16L1 axis that initiates bacteria-induced autophagy. Here we show that SopF is an ADP-ribosyltransferase specifically modifying Gln124 of ATP6V0C in V-ATPase. We identify GTP-bound ADP-ribosylation factor (ARF) GTPases as a cofactor required for SopF functioning. Crystal structures of SopF-ARF1 complexes not only reveal structural basis of SopF ADP-ribosyltransferase activity but also a unique effector-binding mode adopted by ARF GTPases. Further, the N terminus of ARF1, although dispensable for high-affinity binding to SopF, is critical for activating SopF to modify ATP6V0C. Moreover, lysosome or Golgi damage-induced autophagic LC3 activation is inhibited by SopF or Q124A mutation of ATP6V0C, thus also mediated by the V-ATPase-ATG16L1 axis. In this process, the V-ATPase functions to sense membrane damages, which can be uncoupled from its proton-pumping activity.
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Affiliation(s)
- Yue Xu
- National Institute of Biological Sciences, Beijing, China.,Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Sen Cheng
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.,Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Huan Zeng
- National Institute of Biological Sciences, Beijing, China.,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Ping Zhou
- National Institute of Biological Sciences, Beijing, China
| | - Yan Ma
- National Institute of Biological Sciences, Beijing, China
| | - Lin Li
- National Institute of Biological Sciences, Beijing, China
| | - Xiaoyun Liu
- Institute of Analytical Chemistry and Synthetic and Functional Biomolecules Center, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.,Department of Microbiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Feng Shao
- National Institute of Biological Sciences, Beijing, China. .,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China. .,Research Unit of Pyroptosis and Immunity, Chinese Academy of Medical Sciences and National Institute of Biological Sciences, Beijing, China. .,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China.
| | - Jingjin Ding
- National Institute of Biological Sciences, Beijing, China. .,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
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10
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Badshah SL, Naeem A. Computational Simulation of Conjugated Cholera Toxin Protein. MOLECULAR GENETICS, MICROBIOLOGY AND VIROLOGY 2021. [DOI: 10.3103/s0891416821050049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Novel Nematode-Killing Protein-1 (Nkp-1) from a Marine Epiphytic Bacterium Pseudoalteromonas tunicata. Biomedicines 2021; 9:biomedicines9111586. [PMID: 34829814 PMCID: PMC8615270 DOI: 10.3390/biomedicines9111586] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/22/2021] [Accepted: 10/22/2021] [Indexed: 12/12/2022] Open
Abstract
Drug resistance among parasitic nematodes has resulted in an urgent need for the development of new therapies. However, the high re-discovery rate of anti-nematode compounds from terrestrial environments necessitates a new repository for future drug research. Marine epiphytes are hypothesised to produce nematicidal compounds as a defence against bacterivorous predators, thus representing a promising yet underexplored source for anti-nematode drug discovery. The marine epiphytic bacterium Pseudoalteromonas tunicata is known to produce several bioactive compounds. Screening heterologously expressed genomic libraries of P. tunicata against the nematode Caenorhabditis elegans, identified as an E. coli clone (HG8), shows fast-killing activity. Here we show that clone HG8 produces a novel nematode-killing protein-1 (Nkp-1) harbouring a predicted carbohydrate-binding domain with weak homology to known bacterial pore-forming toxins. We found bacteria expressing Nkp-1 were able to colonise the C. elegans intestine, with exposure to both live bacteria and protein extracts resulting in physical damage and necrosis, leading to nematode death within 24 h of exposure. Furthermore, this study revealed C. elegans dar (deformed anal region) and internal hatching may act as a nematode defence strategy against Nkp-1 toxicity. The characterisation of this novel protein and putative mode of action not only contributes to the development of novel anti-nematode applications in the future but reaffirms the potential of marine epiphytic bacteria as a new source of novel biomolecules.
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12
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Intranasal vaccination with a recombinant protein CTA1-DD-RBF protects mice against hRSV infection. Sci Rep 2021; 11:18641. [PMID: 34545126 PMCID: PMC8452643 DOI: 10.1038/s41598-021-97535-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 08/04/2021] [Indexed: 12/05/2022] Open
Abstract
Human respiratory syncytial virus (hRSV) infection is a major pediatric health concern worldwide. Despite more than half a century of efforts, there is still no commercially available vaccine. In this study, we constructed and purified the recombinant protein CTA1-DD-RBF composed of a CTA1-DD mucosal adjuvant and prefusion F protein (RBF) using Escherichia coli BL21 cells. We studied the immunogenicity of CTA1-DD-RBF in mice. Intranasal immunization with CTA1-DD-RBF stimulated hRSV F-specific IgG1, IgG2a, sIgA, and neutralizing antibodies as well as T cell immunity without inducing lung immunopathology upon hRSV challenge. Moreover, the protective immunity of CTA1-DD-RBF was superior to that of the RBF protein, as confirmed by the assessment of serum-neutralizing activity and viral clearance after challenge. Compared to formalin-inactivated hRSV (FI-RSV), intranasal immunization with CTA1-DD-RBF induced a Th1 immune response. In summary, intranasal immunization with CTA1-DD-RBF is safe and effective in mice. Therefore, CTA1-DD-RBF represents a potential mucosal vaccine candidate for the prevention of human infection with hRSV.
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13
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Zhang X, Yu S, Cheng D, Feng Y, Yang Y, Sun H, Ding J, Wang F. An Attenuated Escherichia coli K88ac LT(S63K)Δ STb Efficiently Provides Protection Against Enterotoxigenic Escherichia coli in the Mouse Model. Front Vet Sci 2021; 7:620255. [PMID: 33644141 PMCID: PMC7907446 DOI: 10.3389/fvets.2020.620255] [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: 10/22/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
To develop an attenuated vaccine candidate against K88ac enterotoxigenic Escherichia coli (ETEC), a novel Escherichia coli (E. coli) K88ac LT(S63K)ΔSTb with LT(S63K) mutation and ST1 deletion was generated using site mutagenesis and λ-Red homologous recombination based on wild paternal ETEC strain C83902. E. coli K88ac LT(S63K)ΔSTb showed very similar fimbriae expression and growth kinetics to the wild strain C83902, but it was significantly attenuated according to the results of a rabbit ligated ileal loop assay and mouse infection study. Oral inoculation with E. coli K88ac LT(S63K)ΔSTb stimulated the mucosa immune response and induced the secretion of IgA to K88ac in the intestines in mice. A challenge experiment revealed that the attenuated strain provided efficient protection against C83902 in the following 7 days and at the 24th day post-inoculation, suggesting that the attenuated isolate could act as an ecological protectant and vaccine in preventing K88ac ETEC.
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Affiliation(s)
- Xinyu Zhang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Shupei Yu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Darong Cheng
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Yu Feng
- Department of Biologics Detection Technology, China Institute of Veterinary Drugs Control, Beijing, China
| | - Yuefei Yang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Huaichang Sun
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Jiabo Ding
- Department of Biologics Detection Technology, China Institute of Veterinary Drugs Control, Beijing, China
| | - Fang Wang
- Department of Biologics Detection Technology, China Institute of Veterinary Drugs Control, Beijing, China
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14
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The N-terminus of Paenibacillus larvae C3larvinA modulates catalytic efficiency. Biosci Rep 2021; 41:227200. [PMID: 33289829 PMCID: PMC7789906 DOI: 10.1042/bsr20203727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 01/21/2023] Open
Abstract
C3larvinA was recently described as a mono-ADP-ribosyltransferase (mART) toxin from the enterobacterial repetitive intergenic consensus (ERIC) III genotype of the agricultural pathogen, Paenibacillus larvae. It was shown to be the full-length, functional version of the previously described C3larvintrunc toxin, due to a 33-residue extension of the N-terminus of the protein. In the present study, a series of deletions and substitutions were made to the N-terminus of C3larvinA to assess the contribution of the α1-helix to toxin structure and function. Catalytic characterization of these variants identified Asp23 and Ala31 residues as supportive to enzymatic function. A third residue, Lys36, was also found to contribute to the catalytic activity of the enzyme. Analysis of the C3larvinA homology model revealed that these three residues were participating in a series of interactions to properly orient both the Q-X-E and S-T-S motifs. Ala31 and Lys36 were found to associate with a structural network of residues previously identified in silico, whereas Asp23 forms novel interactions not previously described. At last, the membrane translocation activity into host target cells of each variant was assessed, highlighting a possible relationship between protein dipole and target cell entry.
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15
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Herrera A, Satchell KJF. Cross-Kingdom Activation of Vibrio Toxins by ADP-Ribosylation Factor Family GTPases. J Bacteriol 2020; 202:e00278-20. [PMID: 32900828 PMCID: PMC7685564 DOI: 10.1128/jb.00278-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pathogenic Vibrio species use many different approaches to subvert, attack, and undermine the host response. The toxins they produce are often responsible for the devastating effects associated with their diseases. These toxins target a variety of host proteins, which leads to deleterious effects, including dissolution of cell organelle integrity and inhibition of protein secretion. Becoming increasingly prevalent as cofactors for Vibrio toxins are proteins of the small GTPase families. ADP-ribosylation factor small GTPases (ARFs) in particular are emerging as a common host cofactor necessary for full activation of Vibrio toxins. While ARFs are not the direct target of Vibrio cholerae cholera toxin (CT), ARF binding is required for its optimal activity as an ADP-ribosyltransferase. The makes caterpillars floppy (MCF)-like and the domain X (DmX) effectors of the Vibrio vulnificus multifunctional autoprocessing repeats-in-toxin (MARTX) toxin also both require ARFs to initiate autoprocessing and activation as independent effectors. ARFs are ubiquitously expressed in eukaryotes and are key regulators of many cellular processes, and as such they are ideal cofactors for Vibrio pathogens that infect many host species. In this review, we cover in detail the known Vibrio toxins that use ARFs as cross-kingdom activators to both stimulate and optimize their activity. We further discuss how these contrast to toxins and effectors from other bacterial species that coactivate, stimulate, or directly modify host ARFs as their mechanisms of action.
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Affiliation(s)
- Alfa Herrera
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Karla J F Satchell
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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16
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Towards the application of Tc toxins as a universal protein translocation system. Nat Commun 2019; 10:5263. [PMID: 31748551 PMCID: PMC6868009 DOI: 10.1038/s41467-019-13253-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/28/2019] [Indexed: 11/25/2022] Open
Abstract
Tc toxins are bacterial protein complexes that inject cytotoxic enzymes into target cells using a syringe-like mechanism. Tc toxins are composed of a membrane translocator and a cocoon that encapsulates a toxic enzyme. The toxic enzyme varies between Tc toxins from different species and is not conserved. Here, we investigate whether the toxic enzyme can be replaced by other small proteins of different origin and properties, namely Cdc42, herpes simplex virus ICP47, Arabidopsis thaliana iLOV, Escherichia coli DHFR, Ras-binding domain of CRAF kinase, and TEV protease. Using a combination of electron microscopy, X-ray crystallography and in vitro translocation assays, we demonstrate that it is possible to turn Tc toxins into customizable molecular syringes for delivering proteins of interest across membranes. We also infer the guidelines that protein cargos must obey in terms of size, charge, and fold in order to apply Tc toxins as a universal protein translocation system. Tc toxins are a major class of bacterial toxin translocation systems that inject toxic enzymes into target cells. Here the authors present functional and structural data showing that the toxic enzyme can be replaced by other small proteins and identify prerequisites required for successful translocation, which could facilitate the development of functional Tc-based protein injection devices.
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17
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Herrera A, Muroski J, Sengupta R, Nguyen HH, Agarwal S, Ogorzalek Loo RR, Mattoo S, Loo JA, Satchell KJF. N-terminal autoprocessing and acetylation of multifunctional-autoprocessing repeats-in-toxins (MARTX) Makes Caterpillars Floppy-like effector is stimulated by adenosine diphosphate (ADP)-Ribosylation Factor 1 in advance of Golgi fragmentation. Cell Microbiol 2019; 22:e13133. [PMID: 31658406 DOI: 10.1111/cmi.13133] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/26/2019] [Accepted: 10/11/2019] [Indexed: 12/17/2022]
Abstract
Studies have successfully elucidated the mechanism of action of several effector domains that comprise the multifunctional-autoprocessing repeats-in-toxins (MARTX) toxins of Vibrio vulnificus. However, the biochemical linkage between the cysteine proteolytic activity of Makes Caterpillars Floppy (MCF)-like effector and its cellular effects remains unknown. In this study, we identify the host cell factors that activate in vivo and in vitro MCF autoprocessing as adenosine diphosphate (ADP)-Ribosylation Factor 1 (ARF1) and ADP-Ribosylation Factor 3 (ARF3). Autoprocessing activity is enhanced when ARF1 is in its active [guanosine triphosphate (GTP)-bound] form compared to the inactive [guanosine diphosphate (GDP)-bound] form. Subsequent to auto-cleavage, MCF is acetylated on its exposed N-terminal glycine residue. Acetylation apparently does not dictate subcellular localization as MCF is found localized throughout the cell. However, the cleaved form of MCF gains the ability to bind to the specialized lipid phosphatidylinositol 5-phosphate enriched in Golgi and other membranes necessary for endocytic trafficking, suggesting that a fraction of MCF may be subcellularly localized. Traditional thin-section electron microscopy, high-resolution cryoAPEX localization, and fluorescent microscopy show that MCF causes Golgi dispersal resulting in extensive vesiculation. In addition, host mitochondria are disrupted and fragmented. Mass spectrometry analysis found no reproducible modifications of ARF1 suggesting that ARF1 is not post-translationally modified by MCF. Further, catalytically active MCF does not stably associate with ARF1. Our data indicate not only that ARF1 is a cross-kingdom activator of MCF, but also that MCF may mediate cytotoxicity by directly targeting another yet to be identified protein. This study begins to elucidate the biochemical activity of this important domain and gives insight into how it may promote disease progression.
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Affiliation(s)
- Alfa Herrera
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - John Muroski
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California
| | - Ranjan Sengupta
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana
| | - Hong Hanh Nguyen
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California
| | - Shivangi Agarwal
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Rachel R Ogorzalek Loo
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA Molecular Biology Institute, University of California-Los Angeles, Los Angeles, California.,UCLA/DOE Institute of Genomics and Proteomics, University of California-Los Angeles, Los Angeles, California
| | - Seema Mattoo
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana.,Purdue Institute for Inflammation, Immunology and Infectious Diseases, Purdue University, West Lafayette, Indiana
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California.,Department of Biological Chemistry, David Geffen School of Medicine, UCLA Molecular Biology Institute, University of California-Los Angeles, Los Angeles, California
| | - Karla J F Satchell
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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18
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Gangopadhyay A, Chakraborty HJ, Datta A. Employing virtual screening and molecular dynamics simulations for identifying hits against the active cholera toxin. Toxicon 2019; 170:1-9. [PMID: 31494206 DOI: 10.1016/j.toxicon.2019.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 08/22/2019] [Accepted: 09/01/2019] [Indexed: 12/24/2022]
Abstract
Cholera is a major global threat, affecting millions each year. The ADP ribosyltransferase activity of the active cholera toxin catalyses the massive loss of water and electrolytes during cholera infections. The active toxin heterodimer comprises the A1 subunit from Vibrio cholerae and ARF (ADP Ribosylation Factor) from the human host. Although the active toxin is a potential target for drug discovery against cholera, it has been scarcely targeted to date. The A1-ARF interface contains a potential druggable site for small molecule inhibitors. By combining a sequential docking and scoring strategy with molecular dynamics (MD) simulations, this study identified hits against the protein-protein interface (PPI) of the active cholera toxin from an in-house library of 9,175 ADMET-screened alkaloids. The docking algorithms and scoring functions of Glide SP, Glide XP, and AutoDock were employed for initial library screening. Three alkaloids were initially selected by docking-based virtual screening. The stability of the hit-toxin complexes was validated by MD simulations. Two of the three hits, namely, A6225 (7-formyldehydrothalicsimidine) and A16503 (1,2,7,8-tetrahydroxy dibenz[cd,f]indol-4(5H)-one), formed stable complexes with the toxin. Analyses of the hydrogen bond occupancies revealed that the hits formed stable hydrogen bonds with the toxin PPI. The hits identified herein can serve as reference compounds for drug discovery against cholera in the future.
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Affiliation(s)
- Aditi Gangopadhyay
- Department of Chemical Technology, University of Calcutta, 92, APC Road, Kolkata 700009, West Bengal, India; DBT Centre for Bioinformatics, Presidency University, Kolkata 700073, West Bengal, India.
| | - Hirak Jyoti Chakraborty
- DBT Centre for Bioinformatics, Presidency University, Kolkata 700073, West Bengal, India; Central Inland Fisheries Research Institute, Barrackpore, Kolkata 700120, West Bengal, India
| | - Abhijit Datta
- DBT Centre for Bioinformatics, Presidency University, Kolkata 700073, West Bengal, India; Department of Botany, Jhargram Raj College, Jhargram 721507, Paschim Medinipur, India
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19
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Makes caterpillars floppy-like effector-containing MARTX toxins require host ADP-ribosylation factor (ARF) proteins for systemic pathogenicity. Proc Natl Acad Sci U S A 2019; 116:18031-18040. [PMID: 31427506 PMCID: PMC6731672 DOI: 10.1073/pnas.1905095116] [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] [Indexed: 12/18/2022] Open
Abstract
MARTX toxins present across multiple bacterial genera are primary virulence factors that facilitate initial colonization, dissemination, and lethality in a wide range of hosts, including humans. Upon entry into host cells, the toxins undergo a processing event to release their disease-related modularly structured effector domains. However, the mechanisms underlying processing and activation of diverse effector domains within the toxins remain unclear. Here, we use biochemical and structural biological approaches, in combination with cellular microbiological experiments, to demonstrate how Makes caterpillars floppy-like effector (MCF) or its homolog-containing MARTX toxins process effector modules and fully activate effectors. MCF-containing toxins target ADP-ribosylation factor proteins ubiquitously expressed in cells to activate and disseminate effectors across subcellular compartments simultaneously, eventually leading to systemic pathogenicity. Upon invading target cells, multifunctional autoprocessing repeats-in-toxin (MARTX) toxins secreted by bacterial pathogens release their disease-related modularly structured effector domains. However, it is unclear how a diverse repertoire of effector domains within these toxins are processed and activated. Here, we report that Makes caterpillars floppy-like effector (MCF)-containing MARTX toxins require ubiquitous ADP-ribosylation factor (ARF) proteins for processing and activation of intermediate effector modules, which localize in different subcellular compartments following limited processing of holo effector modules by the internal cysteine protease. Effector domains structured tandemly with MCF in intermediate modules become disengaged and fully activated by MCF, which aggressively interacts with ARF proteins present at the same location as intermediate modules and is converted allosterically into a catalytically competent protease. MCF-mediated effector processing leads ultimately to severe virulence in mice via an MCF-mediated ARF switching mechanism across subcellular compartments. This work provides insight into how bacteria take advantage of host systems to induce systemic pathogenicity.
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20
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Williams HF, Layfield HJ, Vallance T, Patel K, Bicknell AB, Trim SA, Vaiyapuri S. The Urgent Need to Develop Novel Strategies for the Diagnosis and Treatment of Snakebites. Toxins (Basel) 2019; 11:E363. [PMID: 31226842 PMCID: PMC6628419 DOI: 10.3390/toxins11060363] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/18/2019] [Accepted: 06/18/2019] [Indexed: 01/09/2023] Open
Abstract
Snakebite envenoming (SBE) is a priority neglected tropical disease, which kills in excess of 100,000 people per year. Additionally, many millions of survivors also suffer through disabilities and long-term health consequences. The only treatment for SBE, antivenom, has a number of major associated problems, not least, adverse reactions and limited availability. This emphasises the necessity for urgent improvements to the management of this disease. Administration of antivenom is too frequently based on symptomatology, which results in wasting crucial time. The majority of SBE-affected regions rely on broad-spectrum polyvalent antivenoms that have a low content of case-specific efficacious immunoglobulins. Research into small molecular therapeutics such as varespladib/methyl-varespladib (PLA2 inhibitors) and batimastat/marimastat (metalloprotease inhibitors) suggest that such adjunctive treatments could be hugely beneficial to victims. Progress into toxin-specific monoclonal antibodies as well as alternative binding scaffolds such as aptamers hold much promise for future treatment strategies. SBE is not implicit during snakebite, due to venom metering. Thus, the delay between bite and symptom presentation is critical and when symptoms appear it may often already be too late to effectively treat SBE. The development of reliable diagnostical tools could therefore initiate a paradigm shift in the treatment of SBE. While the complete eradication of SBE is an impossibility, mitigation is in the pipeline, with new treatments and diagnostics rapidly emerging. Here we critically review the urgent necessity for the development of diagnostic tools and improved therapeutics to mitigate the deaths and disabilities caused by SBE.
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Affiliation(s)
| | | | - Thomas Vallance
- School of Pharmacy, University of Reading, Reading RG6 6AH, UK.
| | - Ketan Patel
- School of Biological Sciences, University of Reading, Reading RG6 6AH, UK.
| | - Andrew B Bicknell
- School of Biological Sciences, University of Reading, Reading RG6 6AH, UK.
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21
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Kim MS, Yi EJ, Kim YI, Kim SH, Jung YS, Kim SR, Iwawaki T, Ko HJ, Chang SY. ERdj5 in Innate Immune Cells Is a Crucial Factor for the Mucosal Adjuvanticity of Cholera Toxin. Front Immunol 2019; 10:1249. [PMID: 31275300 PMCID: PMC6593289 DOI: 10.3389/fimmu.2019.01249] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/16/2019] [Indexed: 12/31/2022] Open
Abstract
Cholera toxin (CT) is one of most strong mucosal adjuvants, but it cannot be clinically used owing to its toxicity. The cytosolic A1 subunit of CT (CTA1) is the molecule responsible for its immunostimulatory activity, which increases the concentration of cyclic AMP and causes the induction of pro-inflammatory cytokines in innate immune cells. However, the importance of endoplasmic reticulum (ER) molecules involved in CTA1 retro-translocation to induce immune responses remained to be investigated. ERdj5 is an ER protein which is expected to transfer CTA1 to the Hrd1 complex for the retro-translocation of CTA1. In this study, we investigated the physiological relevance of ERdj5 in immune stimulation by CT. ERdj5-knockout (ERdj5 KO) mice had decreased production of antigen-specific IgG in the serum and IgA in the mucosal secretion after intranasal immunization with Ag and CT. Especially, IgG2c isotypes were specifically reduced in the absence of ERdj5. ERdj5 KO dendritic cells (DCs) failed to full activation with decreased expression of costimulatory molecules, such as MHC class II, CD80, and CD 86. In ERdj5 KO DCs, secretion of pro-inflammatory cytokines, such as IL-1β, TNF-α, and IL-6, was reduced. The cytokine signatures of several helper T cells were reduced in ERdj5 KO mice following intranasal CT immunization. The absence of ERdj5 affects the immunostimulatory properties of CT but does not affect the response to the CTB pentamer, the response to alum, total antibody production, or cytokine release from DCs exposed to CpG. Interestingly, CT enhanced the expression of ER stress proteins in ERdj5 KO innate immune cells. These results suggested that ERdj5 contributed as a decisive factor to the immunostimulatory capacity of CT via CTA1 retro-translocation.
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Affiliation(s)
- Mee-Sun Kim
- College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon-si, South Korea
| | - Eun-Je Yi
- College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon-si, South Korea
| | - Young-In Kim
- College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon-si, South Korea
| | - So Hee Kim
- College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon-si, South Korea
| | - Yi-Sook Jung
- College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon-si, South Korea
| | - Seong-Ryeol Kim
- Laboratory of Microbiology and Immunology, College of Pharmacy, Kangwon National University, Chuncheon-si, South Korea
| | - Takao Iwawaki
- Division of Cell Medicine, Department of Life Science, Medical Research Institute, Kanazawa Medical University, Uchinada, Japan
| | - Hyun-Jeong Ko
- Laboratory of Microbiology and Immunology, College of Pharmacy, Kangwon National University, Chuncheon-si, South Korea
| | - Sun-Young Chang
- College of Pharmacy, and Research Institute of Pharmaceutical Science and Technology (RIPST), Ajou University, Suwon-si, South Korea
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22
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Kumar R, Feltrup TM, Kukreja RV, Patel KB, Cai S, Singh BR. Evolutionary Features in the Structure and Function of Bacterial Toxins. Toxins (Basel) 2019; 11:toxins11010015. [PMID: 30609803 PMCID: PMC6356308 DOI: 10.3390/toxins11010015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/24/2018] [Accepted: 12/25/2018] [Indexed: 12/21/2022] Open
Abstract
Toxins can function both as a harmful and therapeutic molecule, depending on their concentrations. The diversity in their function allows us to ask some very pertinent questions related to their origin and roles: (a) What makes them such effective molecules? (b) Are there evolutionary features encoded within the structures of the toxins for their function? (c) Is structural hierarchy in the toxins important for maintaining their structure and function? (d) Do protein dynamics play a role in the function of toxins? and (e) Do the evolutionary connections to these unique features and functions provide the fundamental points in driving evolution? In light of the growing evidence in structural biology, it would be appropriate to suggest that protein dynamics and flexibility play a much bigger role in the function of the toxin than the structure itself. Discovery of IDPs (intrinsically disorder proteins), multifunctionality, and the concept of native aggregation are shaking the paradigm of the requirement of a fixed three-dimensional structure for the protein’s function. Growing evidence supporting the above concepts allow us to redesign the structure-function aspects of the protein molecules. An evolutionary model is necessary and needs to be developed to study these important aspects. The criteria for a well-defined model would be: (a) diversity in structure and function, (b) unique functionality, and (c) must belong to a family to define the evolutionary relationships. All these characteristics are largely fulfilled by bacterial toxins. Bacterial toxins are diverse and widely distributed in all three forms of life (Bacteria, Archaea and Eukaryotes). Some of the unique characteristics include structural folding, sequence and functional combination of domains, targeting a cellular process to execute their function, and most importantly their flexibility and dynamics. In this work, we summarize certain unique aspects of bacterial toxins, including role of structure in defining toxin function, uniqueness in their enzymatic function, and interaction with their substrates and other proteins. Finally, we have discussed the evolutionary aspects of toxins in detail, which will help us rethink the current evolutionary theories. A careful study, and appropriate interpretations, will provide answers to several questions related to the structure-function relationship of proteins, in general. Additionally, this will also allow us to refine the current evolution theories.
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Affiliation(s)
- Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Thomas M Feltrup
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Roshan V Kukreja
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Kruti B Patel
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
| | - Shuowei Cai
- Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, MA 02747, USA.
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
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23
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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24
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Abstract
The intestinal consequences of cholera enterotoxin are caused by activation of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel through the actions of an as-yet-unknown adenylate cyclase. A new study hunts down this elusive enzyme, showing that mouse and human intestinal epithelium functionally and structurally pair adenylate cyclase isoform 6 (AC6) with CFTR. These findings provide important insights into the molecular mechanisms underlying the robust pathological activation of CFTR activity and promise new opportunities to treat cholera.
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Affiliation(s)
- Christoph O Randak
- Stead Family Department of Pediatrics and the Lung Biology and Cystic Fibrosis Research Center of the Pappajohn Biomedical Institute, University of Iowa, Iowa City, Iowa 52242.
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25
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ADP-ribosylating enterotoxins as vaccine adjuvants. Curr Opin Pharmacol 2018; 41:42-51. [PMID: 29702466 DOI: 10.1016/j.coph.2018.03.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 03/30/2018] [Indexed: 01/18/2023]
Abstract
Most infections are caused by pathogens that access the body at mucosal sites. Hence, development of mucosal vaccines to prevent local infection or invasion of pathogens appears highly warranted, especially since only mucosal immunization will stimulate strong local IgA responses and tissue resident memory CD4 and CD8 T cells. The most significant obstacle to developing such vaccines is the lack of approved adjuvants that can effectively and safely enhance relevant mucosal and systemic immune responses. The most potent mucosal adjuvants known today are the adenosine diphosphate (ADP)-ribosylating bacterial enterotoxins cholera toxin (CT) and Escherichia coli heat-labile toxins (LTs). Unfortunately, these molecules are also very toxic, which precludes their clinical use. However, much effort has been devoted to developing derivatives of these enterotoxins with low or no toxicity and retained adjuvant activity. Although it is fair to say that we know more about how these toxins affect the immune system than ever before, we still lack a detailed understanding of how and why these toxins are effective adjuvants. In the present review, we provide a state-of-the-art overview of the mechanism of action of the holotoxins and the strategies used for improving the toxin-based adjuvants.
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26
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Das S, Angsantikul P, Le C, Bao D, Miyamoto Y, Gao W, Zhang L, Eckmann L. Neutralization of cholera toxin with nanoparticle decoys for treatment of cholera. PLoS Negl Trop Dis 2018; 12:e0006266. [PMID: 29470490 PMCID: PMC5839590 DOI: 10.1371/journal.pntd.0006266] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 03/06/2018] [Accepted: 01/24/2018] [Indexed: 01/16/2023] Open
Abstract
Diarrheal diseases are a major cause of morbidity and mortality worldwide. In many cases, antibiotic therapy is either ineffective or not recommended due to concerns about emergence of resistance. The pathogenesis of several of the most prevalent infections, including cholera and enteroxigenic Escherichia coli, is dominated by enterotoxins produced by lumen-dwelling pathogens before clearance by intestinal defenses. Toxins gain access to the host through critical host receptors, making these receptors attractive targets for alternative antimicrobial strategies that do not rely on conventional antibiotics. Here, we developed a new nanotechnology strategy as a countermeasure against cholera, one of the most important and prevalent toxin-mediated enteric infections. The key host receptor for cholera toxin, monosialotetrahexosylganglioside (GM1), was coated onto the surface of polymeric nanoparticles. The resulting GM1-polymer hybrid nanoparticles were shown to function as toxin decoys by selectively and stably binding cholera toxin, and neutralizing its actions on epithelial cells in vitro and in vivo. Furthermore, the GM1-coated nanoparticle decoys attenuated epithelial 3’,5’-cyclic adenosine monophosphate production and fluid responses to infection with live Vibrio cholera in cell culture and a murine infection model. Together, these studies illustrate that the new nanotechnology-based platform can be employed as a non-traditional antimicrobial strategy for the management of enteric infections with enterotoxin-producing pathogens. Diarrheal diseases are a major cause of suffering and death in the world, particularly in tropical regions with limited health care resources. Many of the most important diarrhea-causing microbes produce toxins that activate fluid secretion in the gut. A prototype pathogen in this category is the cause of cholera, Vibrio cholerae, which is characterized by profuse diarrhea and severe electrolyte disturbances due to the release of cholera toxin. Although treatment with fluids by mouth or injection can save patients from death, they still experience the devastating symptoms of the disease. In the present study, we have developed a new intervention strategy with engineered nanoparticles, particulates than are smaller than one millionth of a meter, which can neutralize cholera toxin in the gut before it can cause the characteristic disease manifestations. This strategy represents a novel interventional approach whose mechanism of action is different from currently existing therapies, thus significantly broadening the medical armamentarium against cholera and perhaps other gut infections that cause diseases dominated by toxin production.
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Affiliation(s)
- Soumita Das
- Department of Pathology, University of California, San Diego, La Jolla, California, United States of America
| | - Pavimol Angsantikul
- Department of Nanoengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Christine Le
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Denny Bao
- Department of Pathology, University of California, San Diego, La Jolla, California, United States of America
| | - Yukiko Miyamoto
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
| | - Weiwei Gao
- Department of Nanoengineering, University of California, San Diego, La Jolla, California, United States of America
| | - Liangfang Zhang
- Department of Nanoengineering, University of California, San Diego, La Jolla, California, United States of America
- * E-mail: (LE); (LZ)
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, La Jolla, California, United States of America
- * E-mail: (LE); (LZ)
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Gunasekara DB, DiSalvo M, Wang Y, Nguyen DL, Reed MI, Speer J, Sims CE, Magness ST, Allbritton NL. Development of Arrayed Colonic Organoids for Screening of Secretagogues Associated with Enterotoxins. Anal Chem 2018; 90:1941-1950. [PMID: 29281259 PMCID: PMC6028038 DOI: 10.1021/acs.analchem.7b04032] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Enterotoxins increase intestinal fluid secretion through modulation of ion channels as well as activation of the enteric nervous and immune systems. Colonic organoids, also known as colonoids, are functionally and phenotypically similar to in vivo colonic epithelium and have been used to study intestinal ion transport and subsequent water flux in physiology and disease models. In conventional cultures, organoids exist as spheroids embedded within a hydrogel patty of extracellular matrix, and they form at multiple depths, impairing efficient imaging necessary to capture data from statistically relevant sample sizes. To overcome these limitations, an analytical platform with colonic organoids localized to the planar surface of a hydrogel layer was developed. The arrays of densely packed colonoids (140 μm average diameter, 4 colonoids/mm2) were generated in a 96-well plate, enabling assay of the response of hundreds of organoids so that organoid subpopulations with distinct behaviors were identifiable. Organoid cell types, monolayer polarity, and growth were similar to those embedded in hydrogel. An automated imaging and analysis platform efficiently tracked over time swelling due to forskolin and fluid movement across the cell monolayer stimulated by cholera toxin. The platform was used to screen compounds associated with the enteric nervous and immune systems for their effect on fluid movement across epithelial cells. Prostaglandin E2 promoted increased water flux in a subset of organoids that resulted in organoid swelling, confirming a role for this inflammatory mediator in diarrheal conditions but also illustrating organoid differences in response to an identical stimulus. By allowing sampling of a large number of organoids, the arrayed organoid platform permits identification of organoid subpopulations intermixed within a larger group of nonresponding organoids. This technique will enable automated, large-scale screening of the impact of drugs, toxins, and other compounds on colonic physiology.
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Affiliation(s)
- Dulan B. Gunasekara
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Matthew DiSalvo
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, NC 27599, USA and North Carolina State University, Raleigh, NC 27607, USA
| | - Yuli Wang
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Daniel L. Nguyen
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Mark I. Reed
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Jennifer Speer
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Christopher E. Sims
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
| | - Scott T. Magness
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, NC 27599, USA and North Carolina State University, Raleigh, NC 27607, USA
- Department of Medicine, Division of Gastroenterology and Hepatology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nancy L. Allbritton
- Department of Chemistry, University of North Carolina at Chapel Hill, NC 27599, USA
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, NC 27599, USA and North Carolina State University, Raleigh, NC 27607, USA
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28
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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: 177] [Impact Index Per Article: 22.1] [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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29
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Sparrer KMJ, Gableske S, Zurenski MA, Parker ZM, Full F, Baumgart GJ, Kato J, Pacheco-Rodriguez G, Liang C, Pornillos O, Moss J, Vaughan M, Gack MU. TRIM23 mediates virus-induced autophagy via activation of TBK1. Nat Microbiol 2017; 2:1543-1557. [PMID: 28871090 PMCID: PMC5658249 DOI: 10.1038/s41564-017-0017-2] [Citation(s) in RCA: 167] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022]
Abstract
Autophagy and interferon (IFN)-mediated innate immunity are critical antiviral defence mechanisms, and recent evidence indicated that tripartite motif (TRIM) proteins are important regulators of both processes. Although the role of TRIM proteins in modulating antiviral cytokine responses has been well established, much less is known about their involvement in autophagy in response to different viral pathogens. Through a targeted RNAi screen examining the relevance of selected TRIM proteins in autophagy induced by herpes simplex virus 1 (HSV-1), encephalomyocarditis virus (EMCV) and influenza A virus (IAV), we identified several TRIM proteins that regulate autophagy in a virus-species-specific manner, as well as a few TRIM proteins that were essential for autophagy triggered by all three viruses and rapamycin, among them TRIM23. TRIM23 was critical for autophagy-mediated restriction of multiple viruses, and this activity was dependent on both its RING E3 ligase and ADP-ribosylation factor (ARF) GTPase activity. Mechanistic studies revealed that unconventional K27-linked auto-ubiquitination of the ARF domain is essential for the GTP hydrolysis activity of TRIM23 and activation of TANK-binding kinase 1 (TBK1) by facilitating its dimerization and ability to phosphorylate the selective autophagy receptor p62. Our work identifies the TRIM23-TBK1-p62 axis as a key component of selective autophagy and further reveals a role for K27-linked ubiquitination in GTPase-dependent TBK1 activation.
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Affiliation(s)
| | - Sebastian Gableske
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Matthew A Zurenski
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Zachary M Parker
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Florian Full
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Gavin J Baumgart
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Jiro Kato
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Gustavo Pacheco-Rodriguez
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Chengyu Liang
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22908, USA
| | - Joel Moss
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Martha Vaughan
- Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Michaela U Gack
- Department of Microbiology, The University of Chicago, Chicago, IL, 60637, USA.
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30
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An Enterotoxin-Like Binary Protein from Pseudomonas protegens with Potent Nematicidal Activity. Appl Environ Microbiol 2017; 83:AEM.00942-17. [PMID: 28733289 PMCID: PMC5601331 DOI: 10.1128/aem.00942-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/05/2017] [Indexed: 11/20/2022] Open
Abstract
Soil microbes are a major food source for free-living soil nematodes. It is known that certain soil bacteria have evolved systems to combat predation. We identified the nematode-antagonistic Pseudomonas protegens strain 15G2 from screening of microbes. Through protein purification we identified a binary protein, designated Pp-ANP, which is responsible for the nematicidal activity. This binary protein inhibits Caenorhabditis elegans growth and development by arresting larvae at the L1 stage and killing older-staged worms. The two subunits, Pp-ANP1a and Pp-ANP2a, are active when reconstituted from separate expression in Escherichia coli. The binary toxin also shows strong nematicidal activity against three other free-living nematodes (Pristionchus pacificus, Panagrellus redivivus, and Acrobeloides sp.), but we did not find any activity against insects and fungi under test conditions, indicating specificity for nematodes. Pp-ANP1a has no significant identity to any known proteins, while Pp-ANP2a shows ∼30% identity to E. coli heat-labile enterotoxin (LT) subunit A and cholera toxin (CT) subunit A. Protein modeling indicates that Pp-ANP2a is structurally similar to CT/LT and likely acts as an ADP-ribosyltransferase. Despite the similarity, Pp-ANP shows several characteristics distinct from CT/LT toxins. Our results indicate that Pp-ANP is a new enterotoxin-like binary toxin with potent and specific activity to nematodes. The potency and specificity of Pp-ANP suggest applications in controlling parasitic nematodes and open an avenue for further research on its mechanism of action and role in bacterium-nematode interaction. IMPORTANCE This study reports the discovery of a new enterotoxin-like binary protein, Pp-ANP, from a Pseudomonas protegens strain. Pp-ANP shows strong nematicidal activity against Caenorhabditis elegans larvae and older-staged worms. It also shows strong activity on other free-living nematodes (Pristionchus pacificus, Panagrellus redivivus, and Acrobeloides sp.). The two subunits, Pp-ANP1a and Pp-ANP2a, can be expressed separately and reconstituted to form the active complex. Pp-ANP shows some distinct characteristics compared with other toxins, including Escherichia coli enterotoxin and cholera toxin. The present study indicates that Pp-ANP is a novel binary toxin and that it has potential applications in controlling parasitic nematodes and in studying toxin-host interaction.
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31
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Oda T, Hirabayashi H, Shikauchi G, Takamura R, Hiraga K, Minami H, Hashimoto H, Yamamoto M, Wakabayashi K, Shimizu T, Sato M. Structural basis of autoinhibition and activation of the DNA-targeting ADP-ribosyltransferase pierisin-1. J Biol Chem 2017; 292:15445-15455. [PMID: 28765284 DOI: 10.1074/jbc.m117.776641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 07/25/2017] [Indexed: 01/10/2023] Open
Abstract
ADP-ribosyltransferases transfer the ADP-ribose moiety of βNAD+ to an acceptor molecule, usually a protein that modulates the function of the acceptor. Pierisin-1 is an ADP-ribosyltransferase from the cabbage butterfly Pieris rapae and is composed of N-terminal catalytic and C-terminal ricin B-like domains. Curiously, it ADP-ribosylates the DNA duplex, resulting in apoptosis of various cancer cells, which has raised interest in pierisin-1 as an anti-cancer agent. However, both the structure and the mechanism of DNA ADP-ribosylation are unclear. Here, we report the crystal structures of the N-terminal catalytic domain of pierisin-1, its complex with βNAD+, and the catalytic domain with the linker connecting it to the ricin B-like domains. We found that the catalytic domain possesses a defined, positively charged region on the molecular surface but that its overall structure is otherwise similar to those of protein-targeting ADP-ribosyltransferases. Electrophoretic mobility shift assays and site-directed mutagenesis indicated that pierisin-1 binds double-stranded but not single-stranded DNA and that Lys122, Lys123, and Lys124, which are found in a loop, and Arg181 and Arg187, located in a basic cleft near the loop, are required for DNA binding. Furthermore, the structure of the catalytic domain with the linker revealed an autoinhibitory mechanism in which the linker occupies and blocks both the βNAD+- and DNA-binding sites, suggesting that proteolytic cleavage to remove the linker is necessary for enzyme catalysis. Our study provides a structural basis for the DNA-acceptor specificity of pierisin-1 and reveals that a self-regulatory mechanism is required for its activity.
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Affiliation(s)
- Takashi Oda
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Hirokazu Hirabayashi
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Gen Shikauchi
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Ryouma Takamura
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Kiyoshi Hiraga
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Hiroshi Minami
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Hiroshi Hashimoto
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.,the School of Pharmaceutical Sciences and
| | - Masafumi Yamamoto
- the Central Institute for Experimental Animals, Kawasaki 210-0821, Japan, and
| | - Keiji Wakabayashi
- the Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Toshiyuki Shimizu
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.,the Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan
| | - Mamoru Sato
- From the Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan,
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32
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Littler DR, Ang SY, Moriel DG, Kocan M, Kleifeld O, Johnson MD, Tran MT, Paton AW, Paton JC, Summers RJ, Schembri MA, Rossjohn J, Beddoe T. Structure-function analyses of a pertussis-like toxin from pathogenic Escherichia coli reveal a distinct mechanism of inhibition of trimeric G-proteins. J Biol Chem 2017; 292:15143-15158. [PMID: 28663369 DOI: 10.1074/jbc.m117.796094] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 06/14/2017] [Indexed: 11/06/2022] Open
Abstract
Pertussis-like toxins are secreted by several bacterial pathogens during infection. They belong to the AB5 virulence factors, which bind to glycans on host cell membranes for internalization. Host cell recognition and internalization are mediated by toxin B subunits sharing a unique pentameric ring-like assembly. Although the role of pertussis toxin in whooping cough is well-established, pertussis-like toxins produced by other bacteria are less studied, and their mechanisms of action are unclear. Here, we report that some extra-intestinal Escherichia coli pathogens (i.e. those that reside in the gut but can spread to other bodily locations) encode a pertussis-like toxin that inhibits mammalian cell growth in vitro We found that this protein, EcPlt, is related to toxins produced by both nontyphoidal and typhoidal Salmonella serovars. Pertussis-like toxins are secreted as disulfide-bonded heterohexamers in which the catalytic ADP-ribosyltransferase subunit is activated when exposed to the reducing environment in mammalian cells. We found here that the reduced EcPlt exhibits large structural rearrangements associated with its activation. We noted that inhibitory residues tethered within the NAD+-binding site by an intramolecular disulfide in the oxidized state dissociate upon the reduction and enable loop restructuring to form the nucleotide-binding site. Surprisingly, although pertussis toxin targets a cysteine residue within the α subunit of inhibitory trimeric G-proteins, we observed that activated EcPlt toxin modifies a proximal lysine/asparagine residue instead. In conclusion, our results reveal the molecular mechanism underpinning activation of pertussis-like toxins, and we also identified differences in host target specificity.
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Affiliation(s)
- Dene R Littler
- From the Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Sheng Y Ang
- the Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Danilo G Moriel
- the School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Martina Kocan
- the Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Oded Kleifeld
- the Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Matthew D Johnson
- From the Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Mai T Tran
- From the Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia
| | - Adrienne W Paton
- the Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia
| | - James C Paton
- the Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia
| | - Roger J Summers
- the Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Mark A Schembri
- the School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jamie Rossjohn
- From the Infection and Immunity Program and Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3800, Australia, .,the Institute of Infection and Immunity, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, Wales, United Kingdom.,the ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia, and
| | - Travis Beddoe
- the Department of Animal, Plant and Soil Science and Centre for AgriBioscience, La Trobe University, Bundoora, Victoria 3086, Australia
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33
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Bhattaram V, Upadhyay A, Yin HB, Mooyottu S, Venkitanarayanan K. Effect of Dietary Minerals on Virulence Attributes of Vibrio cholerae. Front Microbiol 2017; 8:911. [PMID: 28579983 PMCID: PMC5437166 DOI: 10.3389/fmicb.2017.00911] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 05/04/2017] [Indexed: 12/22/2022] Open
Abstract
Vibrio cholerae is a water-borne pathogen responsible for causing a toxin-mediated profuse diarrhea in humans, leading to severe dehydration and death in unattended patients. With increasing reports of antibiotic resistance in V. cholerae, there is a need for alternate interventional strategies for controlling cholera. A potential new strategy for treating infectious diseases involves targeting bacterial virulence rather than growth, where a pathogen’s specific mechanisms critical for causing infection in hosts are inhibited. Since bacterial motility, intestinal colonization and cholera toxin are critical components in V. cholerae pathogenesis, attenuating these virulence factors could potentially control cholera in humans. In this study, the efficacy of sub-inhibitory concentration (SIC, highest concentration not inhibiting bacterial growth) of essential minerals, zinc (Zn), selenium (Se), and manganese (Mn) in reducing V. cholerae motility and adhesion to intestinal epithelial cells (Caco-2), cholera toxin production, and toxin binding to the ganglioside receptor (GM1) was investigated. Additionally, V. cholerae attachment and toxin production in an ex vivo mouse intestine model was determined. Further, the effect of Zn, Se and Mn on V. cholerae virulence genes, ctxAB (toxin production), fliA (motility), tcpA (intestinal colonization), and toxR (master regulon) was determined using real-time quantitative PCR. All three minerals significantly reduced V. cholerae motility, adhesion to Caco-2 cells, and cholera toxin production in vitro, and decreased adhesion and toxin production in mouse intestine ex vivo (P < 0.05). In addition, Zn, Se, and Mn down-regulated the transcription of virulence genes, ctxAB, fliA, and toxR. Results suggest that Zn, Se, and Mn could be potentially used to reduce V. cholerae virulence. However, in vivo studies in an animal model are necessary to validate these results.
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Affiliation(s)
- Varunkumar Bhattaram
- Department of Animal Science, University of Connecticut, StorrsCT, United States
| | - Abhinav Upadhyay
- Department of Animal Science, University of Connecticut, StorrsCT, United States.,Department of Poultry Science, University of Arkansas, FayettevilleAR, United States
| | - Hsin-Bai Yin
- Department of Animal Science, University of Connecticut, StorrsCT, United States
| | - Shankumar Mooyottu
- Department of Animal Science, University of Connecticut, StorrsCT, United States
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34
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Affiliation(s)
- Megan Garland
- Cancer
Biology Program, ‡Department of Pathology, §Department of Microbiology and Immunology, and ∥Department of
Chemical and Systems Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305, United States
| | - Sebastian Loscher
- Cancer
Biology Program, ‡Department of Pathology, §Department of Microbiology and Immunology, and ∥Department of
Chemical and Systems Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305, United States
| | - Matthew Bogyo
- Cancer
Biology Program, ‡Department of Pathology, §Department of Microbiology and Immunology, and ∥Department of
Chemical and Systems Biology, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, California 94305, United States
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35
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Mechanism of the intrinsic arginine finger in heterotrimeric G proteins. Proc Natl Acad Sci U S A 2016; 113:E8041-E8050. [PMID: 27911799 DOI: 10.1073/pnas.1612394113] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterotrimeric G proteins are crucial molecular switches that maintain a large number of physiological processes in cells. The signal is encoded into surface alterations of the Gα subunit that carries GTP in its active state and GDP in its inactive state. The ability of the Gα subunit to hydrolyze GTP is essential for signal termination. Regulator of G protein signaling (RGS) proteins accelerates this process. A key player in this catalyzed reaction is an arginine residue, Arg178 in Gαi1, which is already an intrinsic part of the catalytic center in Gα in contrast to small GTPases, at which the corresponding GTPase-activating protein (GAP) provides the arginine "finger." We applied time-resolved FTIR spectroscopy in combination with isotopic labeling and site-directed mutagenesis to reveal the molecular mechanism, especially of the role of Arg178 in the intrinsic Gαi1 mechanism and the RGS4-catalyzed mechanism. Complementary biomolecular simulations (molecular mechanics with molecular dynamics and coupled quantum mechanics/molecular mechanics) were performed. Our findings show that Arg178 is bound to γ-GTP for the intrinsic Gαi1 mechanism and pushed toward a bidentate α-γ-GTP coordination for the Gαi1·RGS4 mechanism. This movement induces a charge shift toward β-GTP, increases the planarity of γ-GTP, and thereby catalyzes the hydrolysis.
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36
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Dubreuil JD, Isaacson RE, Schifferli DM. Animal Enterotoxigenic Escherichia coli. EcoSal Plus 2016; 7:10.1128/ecosalplus.ESP-0006-2016. [PMID: 27735786 PMCID: PMC5123703 DOI: 10.1128/ecosalplus.esp-0006-2016] [Citation(s) in RCA: 196] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 12/13/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is the most common cause of E. coli diarrhea in farm animals. ETEC are characterized by the ability to produce two types of virulence factors: adhesins that promote binding to specific enterocyte receptors for intestinal colonization and enterotoxins responsible for fluid secretion. The best-characterized adhesins are expressed in the context of fimbriae, such as the F4 (also designated K88), F5 (K99), F6 (987P), F17, and F18 fimbriae. Once established in the animal small intestine, ETEC produce enterotoxin(s) that lead to diarrhea. The enterotoxins belong to two major classes: heat-labile toxins that consist of one active and five binding subunits (LT), and heat-stable toxins that are small polypeptides (STa, STb, and EAST1). This review describes the disease and pathogenesis of animal ETEC, the corresponding virulence genes and protein products of these bacteria, their regulation and targets in animal hosts, as well as mechanisms of action. Furthermore, vaccines, inhibitors, probiotics, and the identification of potential new targets by genomics are presented in the context of animal ETEC.
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Affiliation(s)
- J Daniel Dubreuil
- Faculté de Médecine Vétérinaire, Université de Montréal, Québec J2S 7C6, Canada
| | - Richard E Isaacson
- Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108
| | - Dieter M Schifferli
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
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37
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Galindo A, Soler N, McLaughlin SH, Yu M, Williams RL, Munro S. Structural Insights into Arl1-Mediated Targeting of the Arf-GEF BIG1 to the trans-Golgi. Cell Rep 2016; 16:839-50. [PMID: 27373159 PMCID: PMC4956616 DOI: 10.1016/j.celrep.2016.06.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 05/09/2016] [Accepted: 06/02/2016] [Indexed: 11/28/2022] Open
Abstract
The GTPase Arf1 is the major regulator of vesicle traffic at both the cis- and trans-Golgi. Arf1 is activated at the cis-Golgi by the guanine nucleotide exchange factor (GEF) GBF1 and at the trans-Golgi by the related GEF BIG1 or its paralog, BIG2. The trans-Golgi-specific targeting of BIG1 and BIG2 depends on the Arf-like GTPase Arl1. We find that Arl1 binds to the dimerization and cyclophilin binding (DCB) domain in BIG1 and report a crystal structure of human Arl1 bound to this domain. Residues in the DCB domain that bind Arl1 are required for BIG1 to locate to the Golgi in vivo. DCB domain-binding residues in Arl1 have a distinct conformation from those in known Arl1-effector complexes, and this plasticity allows Arl1 to interact with different effectors of unrelated structure. The findings provide structural insight into how Arf1 GEFs, and hence active Arf1, achieve their correct subcellular distribution.
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Affiliation(s)
- Antonio Galindo
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Nicolas Soler
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Stephen H McLaughlin
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Minmin Yu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Roger L Williams
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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Kim BS, Satchell KJF. MARTX effector cross kingdom activation by Golgi-associated ADP-ribosylation factors. Cell Microbiol 2016; 18:1078-93. [PMID: 26780191 DOI: 10.1111/cmi.12568] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/28/2015] [Accepted: 01/10/2016] [Indexed: 02/07/2023]
Abstract
Vibrio vulnificus infects humans and causes lethal septicemia. The primary virulence factor is a multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin consisting of conserved repeats-containing regions and various effector domains. Recent genomic analyses for the newly emerged V. vulnificus biotype 3 strain revealed that its MARTX toxin has two previously unknown effector domains. Herein, we characterized one of these domains, Domain X (DmXVv ). A structure-based homology search revealed that DmXVv belongs to the C58B cysteine peptidase subfamily. When ectopically expressed in cells, DmXVv was autoprocessed and induced cytopathicity including Golgi dispersion. When the catalytic cysteine or the region flanking the scissile bond was mutated, both autoprocessing and cytopathicity were significantly reduced indicating that DmXVv cytopathicity is activated by amino-terminal autoprocessing. Consistent with this, host cell protein export was affected by Vibrio cells producing a toxin with wild-type, but not catalytically inactive, DmXVv . DmXVv was found to localize to Golgi and to directly interact with Golgi-associated ADP-ribosylation factors ARF1, ARF3 and ARF4, although ARF binding was not necessary for the subcellular localization. Rather, this interaction was found to induce autoprocessing of DmXVv . These data demonstrate that the V. vulnificus hijacks the host ARF proteins to activate the cytopathic DmXVv effector domain of MARTX toxin.
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Affiliation(s)
- Byoung Sik Kim
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Karla J F Satchell
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
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Host Cell Chaperones Hsp70/Hsp90 and Peptidyl-Prolyl Cis/Trans Isomerases Are Required for the Membrane Translocation of Bacterial ADP-Ribosylating Toxins. Curr Top Microbiol Immunol 2016; 406:163-198. [PMID: 27197646 DOI: 10.1007/82_2016_14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacterial ADP-ribosylating toxins are the causative agents for several severe human and animal diseases such as diphtheria, cholera, or enteric diseases. They display an AB-type structure: The enzymatically active A-domain attaches to the binding/translocation B-domain which then binds to a receptor on the cell surface. After receptor-mediated endocytosis, the B-domain facilitates the membrane translocation of the unfolded A-domain into the host cell cytosol. Here, the A-domain transfers an ADP-ribose moiety onto its specific substrate which leads to characteristic cellular effects and thus to severe clinical symptoms. Since the A-domain has to reach the cytosol to achieve a cytotoxic effect, the membrane translocation represents a crucial step during toxin uptake. Host cell chaperones including Hsp90 and protein-folding helper enzymes of the peptidyl-prolyl cis/trans isomerase (PPIase) type facilitate this membrane translocation of the unfolded A-domain for ADP-ribosylating toxins but not for toxins with a different enzyme activity. This review summarizes the uptake mechanisms of the ADP-ribosylating clostridial binary toxins, diphtheria toxin (DT) and cholera toxin (CT), with a special focus on the interaction of these toxins with the chaperones Hsp90 and Hsp70 and PPIases of the cyclophilin and FK506-binding protein families during the membrane translocation of their ADP-ribosyltransferase domains into the host cell cytosol. Moreover, the medical implications of host cell chaperones and PPIases as new drug targets for the development of novel therapeutic strategies against diseases caused by bacterial ADP-ribosylating toxins are discussed.
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Badshah SL, Khan AN, Mabkhot YN. Molecular Dynamics Simulation of Cholera Toxin A-1 Polypeptide. OPEN CHEM 2016. [DOI: 10.1515/chem-2016-0021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
AbstractA molecular dynamics (MD) simulation study of the enzymatic portion of cholera toxin; cholera toxin A-1 polypeptide (CTA1) was performed at 283, 310 and 323 K. From total energy analysis it was observed that this toxin is stable thermodynamically and these outcomes were likewise confirmed by root mean square deviations (RMSD) investigations. The Cα root mean square fluctuation (RMSF) examinations revealed that there are a number of residues inside CTA1, which can be used as target for designing and synthesizing inhibitory drugs, in order to inactivate cholera toxin inside the human body. The fluctuations in the radius of gyration and hydrogen bonding in CTA1 proved that protein unfolding and refolding were normal routine phenomena in its structure at all temperatures. Solvent accessible surface area study identified the hydrophilic nature of the CTA1, and due to this property it can be a potential biological weapon. The structural identification (STRIDE) algorithm for proteins was successfully used to determine the partially disordered secondary structure of CTA1. On account of this partially disordered secondary structure, it can easily deceive the proteolytic enzymes of the endoplasmic reticulum of host cells.
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Affiliation(s)
- Syed Lal Badshah
- 1National Center of Excellence in Physical Chemistry, University of Peshawar, Khyber Pukhtoonkhwa, Pakistan. 25120
- 2Department Biochemistry, Abdul Wali Khan University Mardan. Khyber Pukhtoonkhwa, Pakistan
- 3Department of Chemistry, Islamia College University Peshawar, Peshawar, Khyber Pukhtoonkhwa, Pakistan. 25120
| | - Abdul Naeem Khan
- 1National Center of Excellence in Physical Chemistry, University of Peshawar, Khyber Pukhtoonkhwa, Pakistan. 25120
- 2Department Biochemistry, Abdul Wali Khan University Mardan. Khyber Pukhtoonkhwa, Pakistan
| | - Yahia Nasser Mabkhot
- 3Department of Chemistry, Islamia College University Peshawar, Peshawar, Khyber Pukhtoonkhwa, Pakistan. 25120
- 4Department of Chemistry, College of Sciences, King Saud University, Riyadh 11451. Saudi Arabia
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Selection of Single-Stranded DNA Molecular Recognition Elements against Exotoxin A Using a Novel Decoy-SELEX Method and Sensitive Detection of Exotoxin A in Human Serum. BIOMED RESEARCH INTERNATIONAL 2015; 2015:417641. [PMID: 26636098 PMCID: PMC4655287 DOI: 10.1155/2015/417641] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/09/2015] [Accepted: 10/12/2015] [Indexed: 12/04/2022]
Abstract
Exotoxin A is one of the virulence factors of Pseudomonas aeruginosa, a bacterium that can cause infections resulting in adverse health outcomes and increased burden to health care systems. Current methods of diagnosing P. aeruginosa infections are time consuming and can require significant preparation of patient samples. This study utilized a novel variation of the Systematic Evolution of Ligand by Exponential Enrichment, Decoy-SELEX, to identify an Exotoxin A specific single-stranded DNA (ssDNA) molecular recognition element (MRE). Its emphasis is on increasing stringency in directing binding toward free target of interest and at the same time decreasing binding toward negative targets. A ssDNA MRE with specificity and affinity was identified after fourteen rounds of Decoy-SELEX. Utilizing surface plasmon resonance measurements, the determined equilibrium dissociation constant (Kd) of the MRE is between 4.2 µM and 4.5 µM, and is highly selective for Exotoxin A over negative targets. A ssDNA MRE modified sandwich enzyme-linked immunosorbent assay (ELISA) has been developed and achieved sensitive detection of Exotoxin A at nanomolar concentrations in human serum. This study has demonstrated the proof-of-principle of using a ssDNA MRE as a clinical diagnostic tool.
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Shao X, Liu K, Fan Y, Ding Z, Chen M, Zhu M, Weinstein LS, Li H, Li H. Gαs Relays Sphingosine-1-Phosphate Receptor 1 Signaling to Stabilize Vascular Endothelial-Cadherin at Endothelial Junctions to Control Mouse Embryonic Vascular Integrity. J Genet Genomics 2015; 42:613-624. [PMID: 26674379 DOI: 10.1016/j.jgg.2015.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 08/02/2015] [Accepted: 08/03/2015] [Indexed: 02/05/2023]
Abstract
Sphingosine-1-phosphate receptor 1 (S1PR1), a G protein-coupled receptor (GPCR), controls vascular stability by stabilizing vascular endothelial (VE)-cadherin junctional localization and inhibiting vascular endothelial growth factor receptor 2 (VEGFR2) signaling. However, the molecular mechanisms that link S1PR1 signaling to intracellular effectors remain unknown. In this study, we demonstrate that the heterotrimeric G protein subfamily member Gαs, encoded by GNAS, acts as a relay mediator of S1PR1 signaling to control vascular integrity by stabilizing VE-cadherin at endothelial junctions. The endothelial cell-specific deletion of Gαs in mice causes early embryonic lethality with massive hemorrhage and a disorganized vasculature. The immunostaining results revealed that Gαs deletion remarkably reduces the junctional localization of VE-cadherin, whereas the mural cell coverage of the vessels is not impaired. In addition, we found that Gαs depletion blocks the S1PR1-activation induced VE-cadherin stabilization at junctions, supporting that Gαs acts downstream of S1PR1 signaling. Thus, our results demonstrate that Gαs is an essential mediator to relay S1PR1 signaling and maintain vascular integrity.
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Affiliation(s)
- Ximing Shao
- West China Developmental and Stem Cell Institute, West China Second Hospital, Sichuan University, Chengdu 610041, China; State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; Shenzhen Key Laboratory for Molecular Biology of Neural Development, Laboratory of Developmental and Regenerative Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Ke Liu
- West China Developmental and Stem Cell Institute, West China Second Hospital, Sichuan University, Chengdu 610041, China; State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; Shenzhen Key Laboratory for Molecular Biology of Neural Development, Laboratory of Developmental and Regenerative Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Yi Fan
- West China Developmental and Stem Cell Institute, West China Second Hospital, Sichuan University, Chengdu 610041, China; State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China
| | - Zhihao Ding
- Shenzhen Key Laboratory for Molecular Biology of Neural Development, Laboratory of Developmental and Regenerative Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Min Chen
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Minyan Zhu
- SARITEX Center for Stem Cell Engineering Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China
| | - Lee S Weinstein
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hongchang Li
- Shenzhen Key Laboratory for Molecular Biology of Neural Development, Laboratory of Developmental and Regenerative Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
| | - Huashun Li
- West China Developmental and Stem Cell Institute, West China Second Hospital, Sichuan University, Chengdu 610041, China; State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu 610041, China; SARITEX Center for Stem Cell Engineering Translational Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200123, China; Nerdbio Inc., SIP Biobay, Suzhou 215213, China.
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Abstract
Heat-labile enterotoxins (LTs) of Escherichia coli are closely related to cholera toxin (CT), which was originally discovered in 1959 in culture filtrates of the gram-negative bacterium Vibrio cholerae. Several other gram-negative bacteria also produce enterotoxins related to CT and LTs, and together these toxins form the V. cholerae-E. coli family of LTs. Strains of E. coli causing a cholera-like disease were designated enterotoxigenic E. coli (ETEC) strains. The majority of LTI genes (elt) are located on large, self-transmissible or mobilizable plasmids, although there are instances of LTI genes being located on chromosomes or carried by a lysogenic phage. The stoichiometry of A and B subunits in holotoxin requires the production of five B monomers for every A subunit. One proposed mechanism is a more efficient ribosome binding site for the B gene than for the A gene, increasing the rate of initiation of translation of the B gene independently from A gene translation. The three-dimensional crystal structures of representative members of the LT family (CT, LTpI, and LTIIb) have all been determined by X-ray crystallography and found to be highly similar. Site-directed mutagenesis has identified many residues in the CT and LT A subunits, including His44, Val53, Ser63, Val97, Glu110, and Glu112, that are critical for the structures and enzymatic activities of these enterotoxins. For the enzymatically active A1 fragment to reach its substrate, receptor-bound holotoxin must gain access to the cytosol of target cells.
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Large-scale identification of encystment-related proteins and genes in Pseudourostyla cristata. Sci Rep 2015; 5:11360. [PMID: 26079518 PMCID: PMC4650649 DOI: 10.1038/srep11360] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 05/22/2015] [Indexed: 11/08/2022] Open
Abstract
The transformation of a ciliate into cyst is an advance strategy against an adverse situation. However, the molecular mechanism for the encystation of free-living ciliates is poorly understood. A large-scale identification of the encystment-related proteins and genes in ciliate would provide us with deeper insights into the molecular mechanisms for the encystations of ciliate. We identified the encystment-related proteins and genes in Pseudourostyla cristata with shotgun LC-MS/MS and scale qRT-PCR, respectively, in this report. A total of 668 proteins were detected in the resting cysts, 102 of these proteins were high credible proteins, whereas 88 high credible proteins of the 724 total proteins were found in the vegetative cells. Compared with the vegetative cell, 6 specific proteins were found in the resting cyst. However, the majority of high credible proteins in the resting cyst and the vegetative cell were co-expressed. We compared 47 genes of the co-expressed proteins with known functions in both the cyst and the vegetative cell using scale qRT-PCR. Twenty-seven of 47 genes were differentially expressed in the cyst compared with the vegetative cell. In our identifications, many uncharacterized proteins were also found. These results will help reveal the molecular mechanism for the formation of cyst in ciliates.
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Toda A, Tsurumura T, Yoshida T, Tsumori Y, Tsuge H. Rho GTPase Recognition by C3 Exoenzyme Based on C3-RhoA Complex Structure. J Biol Chem 2015; 290:19423-32. [PMID: 26067270 DOI: 10.1074/jbc.m115.653220] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Indexed: 12/18/2022] Open
Abstract
C3 exoenzyme is a mono-ADP-ribosyltransferase (ART) that catalyzes transfer of an ADP-ribose moiety from NAD(+) to Rho GTPases. C3 has long been used to study the diverse regulatory functions of Rho GTPases. How C3 recognizes its substrate and how ADP-ribosylation proceeds are still poorly understood. Crystal structures of C3-RhoA complex reveal that C3 recognizes RhoA via the switch I, switch II, and interswitch regions. In C3-RhoA(GTP) and C3-RhoA(GDP), switch I and II adopt the GDP and GTP conformations, respectively, which explains why C3 can ADP-ribosylate both nucleotide forms. Based on structural information, we successfully changed Cdc42 to an active substrate with combined mutations in the C3-Rho GTPase interface. Moreover, the structure reflects the close relationship among Gln-183 in the QXE motif (C3), a modified Asn-41 residue (RhoA) and NC1 of NAD(H), which suggests that C3 is the prototype ART. These structures show directly for the first time that the ARTT loop is the key to target protein recognition, and they also serve to bridge the gaps among independent studies of Rho GTPases and C3.
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Affiliation(s)
- Akiyuki Toda
- From the Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, and
| | - Toshiharu Tsurumura
- From the Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, and the Structural Biology Research Center, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto 603-8555, Japan
| | - Toru Yoshida
- From the Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, and the Structural Biology Research Center, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto 603-8555, Japan
| | - Yayoi Tsumori
- From the Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, and
| | - Hideaki Tsuge
- From the Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, and the Structural Biology Research Center, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto 603-8555, Japan
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Chiou E, Zennadi R. Gαs proteins activate p72(Syk) and p60-c-Src tyrosine kinases to mediate sickle red blood cell adhesion to endothelium via LW-αvβ3 and CD44-CD44 interactions. Int J Biochem Cell Biol 2015; 65:40-51. [PMID: 26007235 DOI: 10.1016/j.biocel.2015.05.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 04/16/2015] [Accepted: 05/14/2015] [Indexed: 12/13/2022]
Abstract
G protein-coupled receptors (GPCRs) have been suggested as new drug targets to treat a variety of diseases. In sickle cell disease (SCD), the LW erythrocyte adhesion receptor can be activated by stimulation of β2 adrenergic receptors (β2ARs), to mediate sickle erythrocyte (SSRBC) adhesion to endothelium. However, the involvement of tyrosine protein kinases in β2AR signaling to activate SSRBC adhesion to endothelium has not been thoroughly elucidated. Either direct activation with Cholera toxin of Gαs protein, which acts downstream of β2ARs, or inhibition with Pertussis toxin of Gαi, mediating suppression of adenylyl cyclase, increased SSRBC adhesion to endothelium over baseline adhesion. This effect involved the non-receptor tyrosine kinases, p72(Syk) and p60-c-Src, which were more abundant in SSRBCs than in normal erythrocytes. In contrast, Pertussis toxin and Cholera toxin failed to increase adhesion of normal erythrocytes. SSRBC Gαi inhibition also increased phosphorylation of p72(Syk) and p60-c-Src. Further, we investigated the relevance of activation of p72(Syk) and p60-c-Src, and identified LW (ICAM-4, CD242) and CD44 as the erythroid adhesion molecules both physically interacting with activated p60-c-Src. As a result, SSRBC LW underwent increased tyrosine phosphorylation, leading to SSRBC LW and CD44 binding to endothelial αvβ3 integrin and CD44, respectively. These data provide in vitro mechanistic evidence that p60-c-Src, which could act downstream of Gαs/p72(Syk), associates with LW and CD44 on SSRBCs leading to their interactions with endothelial αvβ3 and CD44, respectively. Thus, increased activation of these signaling mechanisms in SSRBCs could initiate or exacerbate vascular occlusion, the hallmark of SCD.
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Affiliation(s)
- Edward Chiou
- Division of Hematology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, United States
| | - Rahima Zennadi
- Division of Hematology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, United States.
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Structure of CARDS toxin, a unique ADP-ribosylating and vacuolating cytotoxin from Mycoplasma pneumoniae. Proc Natl Acad Sci U S A 2015; 112:5165-70. [PMID: 25848012 DOI: 10.1073/pnas.1420308112] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mycoplasma pneumoniae (Mp) infections cause tracheobronchitis and "walking" pneumonia, and are linked to asthma and other reactive airway diseases. As part of the infectious process, the bacterium expresses a 591-aa virulence factor with both mono-ADP ribosyltransferase (mART) and vacuolating activities known as Community-Acquired Respiratory Distress Syndrome Toxin (CARDS TX). CARDS TX binds to human surfactant protein A and annexin A2 on airway epithelial cells and is internalized, leading to a range of pathogenetic events. Here we present the structure of CARDS TX, a triangular molecule in which N-terminal mART and C-terminal tandem β-trefoil domains associate to form an overall architecture distinct from other well-recognized ADP-ribosylating bacterial toxins. We demonstrate that CARDS TX binds phosphatidylcholine and sphingomyelin specifically over other membrane lipids, and that cell surface binding and internalization activities are housed within the C-terminal β-trefoil domain. The results enhance our understanding of Mp pathogenicity and suggest a novel avenue for the development of therapies to treat Mp-associated asthma and other acute and chronic airway diseases.
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48
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Identification of inhibitors against the potential ligandable sites in the active cholera toxin. Comput Biol Chem 2015; 55:37-48. [DOI: 10.1016/j.compbiolchem.2015.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 01/29/2015] [Accepted: 02/04/2015] [Indexed: 11/23/2022]
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49
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Mott HR, Owen D. Structures of Ras superfamily effector complexes: What have we learnt in two decades? Crit Rev Biochem Mol Biol 2015; 50:85-133. [PMID: 25830673 DOI: 10.3109/10409238.2014.999191] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The Ras superfamily small G proteins are master regulators of a diverse range of cellular processes and act via downstream effector molecules. The first structure of a small G protein-effector complex, that of Rap1A with c-Raf1, was published 20 years ago. Since then, the structures of more than 60 small G proteins in complex with their effectors have been published. These effectors utilize a diverse array of structural motifs to interact with the G protein fold, which we have divided into four structural classes: intermolecular β-sheets, helical pairs, other interactions, and pleckstrin homology (PH) domains. These classes and their representative structures are discussed and a contact analysis of the interactions is presented, which highlights the common effector-binding regions between and within the small G protein families.
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Affiliation(s)
- Helen R Mott
- Department of Biochemistry, University of Cambridge , Cambridge , UK
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50
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A mutational analysis of residues in cholera toxin A1 necessary for interaction with its substrate, the stimulatory G protein Gsα. Toxins (Basel) 2015; 7:919-35. [PMID: 25793724 PMCID: PMC4379533 DOI: 10.3390/toxins7030919] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/27/2015] [Accepted: 03/04/2015] [Indexed: 01/10/2023] Open
Abstract
Pathogenesis of cholera diarrhea requires cholera toxin (CT)-mediated adenosine diphosphate (ADP)-ribosylation of stimulatory G protein (Gsα) in enterocytes. CT is an AB5 toxin with an inactive CTA1 domain linked via CTA2 to a pentameric receptor-binding B subunit. Allosterically activated CTA1 fragment in complex with NAD+ and GTP-bound ADP-ribosylation factor 6 (ARF6-GTP) differs conformationally from the CTA1 domain in holotoxin. A surface-exposed knob and a short α-helix (formed, respectively, by rearranging “active-site” and “activation” loops in inactive CTA1) and an ADP ribosylating turn-turn (ARTT) motif, all located near the CTA1 catalytic site, were evaluated for possible roles in recognizing Gsα. CT variants with one, two or three alanine substitutions at surface-exposed residues within these CTA1 motifs were tested for assembly into holotoxin and ADP-ribosylating activity against Gsα and diethylamino-(benzylidineamino)-guanidine (DEABAG), a small substrate predicted to fit into the CTA1 active site). Variants with single alanine substitutions at H55, R67, L71, S78, or D109 had nearly wild-type activity with DEABAG but significantly decreased activity with Gsα, suggesting that the corresponding residues in native CTA1 participate in recognizing Gsα. As several variants with multiple substitutions at these positions retained partial activity against Gsα, other residues in CTA1 likely also participate in recognizing Gsα.
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