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Vascon F, Gasparotto M, Giacomello M, Cendron L, Bergantino E, Filippini F, Righetto I. Protein electrostatics: From computational and structural analysis to discovery of functional fingerprints and biotechnological design. Comput Struct Biotechnol J 2020; 18:1774-1789. [PMID: 32695270 PMCID: PMC7355722 DOI: 10.1016/j.csbj.2020.06.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 06/16/2020] [Accepted: 06/19/2020] [Indexed: 12/31/2022] Open
Abstract
Computationally driven engineering of proteins aims to allow them to withstand an extended range of conditions and to mediate modified or novel functions. Therefore, it is crucial to the biotechnological industry, to biomedicine and to afford new challenges in environmental sciences, such as biocatalysis for green chemistry and bioremediation. In order to achieve these goals, it is important to clarify molecular mechanisms underlying proteins stability and modulating their interactions. So far, much attention has been given to hydrophobic and polar packing interactions and stability of the protein core. In contrast, the role of electrostatics and, in particular, of surface interactions has received less attention. However, electrostatics plays a pivotal role along the whole life cycle of a protein, since early folding steps to maturation, and it is involved in the regulation of protein localization and interactions with other cellular or artificial molecules. Short- and long-range electrostatic interactions, together with other forces, provide essential guidance cues in molecular and macromolecular assembly. We report here on methods for computing protein electrostatics and for individual or comparative analysis able to sort proteins by electrostatic similarity. Then, we provide examples of electrostatic analysis and fingerprints in natural protein evolution and in biotechnological design, in fields as diverse as biocatalysis, antibody and nanobody engineering, drug design and delivery, molecular virology, nanotechnology and regenerative medicine.
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Affiliation(s)
- Filippo Vascon
- Synthetic Biology and Biotechnology Unit, Department of Biology, University of Padua, Italy
| | - Matteo Gasparotto
- Synthetic Biology and Biotechnology Unit, Department of Biology, University of Padua, Italy
| | - Marta Giacomello
- Bioenergetic Organelles Unit, Department of Biology, University of Padua, Italy
- Department of Biomedical Sciences, University of Padua, Italy
| | - Laura Cendron
- Synthetic Biology and Biotechnology Unit, Department of Biology, University of Padua, Italy
| | - Elisabetta Bergantino
- Synthetic Biology and Biotechnology Unit, Department of Biology, University of Padua, Italy
| | - Francesco Filippini
- Synthetic Biology and Biotechnology Unit, Department of Biology, University of Padua, Italy
| | - Irene Righetto
- Synthetic Biology and Biotechnology Unit, Department of Biology, University of Padua, Italy
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2
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Varela-Chavez C, Blondel A, Popoff MR. Bacterial intracellularly active toxins: Membrane localisation of the active domain. Cell Microbiol 2020; 22:e13213. [PMID: 32353188 DOI: 10.1111/cmi.13213] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 04/06/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022]
Abstract
Numerous bacterial toxins exert their activity by inactivating or modulating a specific intracellular host target. For this purpose, these toxins have developed efficient strategies to overcome the different host cell defences including specific binding to cell surface, internalisation, passage through the endosome or plasma membrane, exploiting intracellular trafficking and addressing to intracellular targets. Several intracellularly active toxins deliver an active domain into the cytosol that interacts with a target localised to the inner face of the plasma membrane. Thus, the large clostridial glucosylating toxins (LCGTs) target Rho/Ras-GTPases, certain virulence factors of Gram negative bacteria, Rho-GTPases, while Pasteurella multocida toxin (PMT) targets trimeric G-proteins. Others such as botulinum neurotoxins and tetanus neurotoxin have their substrate on synaptic vesicle membrane. LCGTs, PMT, and certain virulence factors from Vibrio sp. show a particular structure constituted of a four-helix bundle membrane (4HBM) protruding from the catalytic site that specifically binds to the membrane phospholipids and then trap the catalytic domain at the proximity of the membrane anchored substrate. Structural and functional analysis indicate that the 4HBM tip of the Clostridium sordellii lethal toxin (TcsL) from the LCGT family contain two loops forming a cavity that mediates the binding to phospholipids and more specifically to phosphatidylserine.
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Affiliation(s)
| | - Arnaud Blondel
- Unité de Bio-Informatique Structurale, Institut Pasteur, Paris, France
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3
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Yahalom A, Davidov G, Kolusheva S, Shaked H, Barber-Zucker S, Zarivach R, Chill JH. Structure and membrane-targeting of a Bordetella pertussis effector N-terminal domain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183054. [DOI: 10.1016/j.bbamem.2019.183054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/05/2019] [Accepted: 08/22/2019] [Indexed: 01/07/2023]
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4
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Chen P, Lam KH, Liu Z, Mindlin FA, Chen B, Gutierrez CB, Huang L, Zhang Y, Hamza T, Feng H, Matsui T, Bowen ME, Perry K, Jin R. Structure of the full-length Clostridium difficile toxin B. Nat Struct Mol Biol 2019; 26:712-719. [PMID: 31308519 PMCID: PMC6684407 DOI: 10.1038/s41594-019-0268-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 06/07/2019] [Indexed: 01/07/2023]
Abstract
Clostridium difficile is an opportunistic pathogen that establishes in the colon when the gut microbiota are disrupted by antibiotics or disease. C. difficile infection (CDI) is largely caused by two virulence factors, TcdA and TcdB. Here, we report a 3.87-Å-resolution crystal structure of TcdB holotoxin that captures a unique conformation of TcdB at endosomal pH. Complementary biophysical studies suggest that the C-terminal combined repetitive oligopeptides (CROPs) domain of TcdB is dynamic and can sample open and closed conformations that may facilitate modulation of TcdB activity in response to environmental and cellular cues during intoxication. Furthermore, we report three crystal structures of TcdB-antibody complexes that reveal how antibodies could specifically inhibit the activities of individual TcdB domains. Our studies provide novel insight into the structure and function of TcdB holotoxin and identify intrinsic vulnerabilities that could be exploited to develop new therapeutics and vaccines for the treatment of CDI.
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Affiliation(s)
- Peng Chen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Kwok-Ho Lam
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Zheng Liu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Frank A Mindlin
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Baohua Chen
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Craig B Gutierrez
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA
| | - Yongrong Zhang
- Department of Microbial Pathogenesis, University of Maryland Baltimore, Baltimore, MD, USA
| | - Therwa Hamza
- Department of Microbial Pathogenesis, University of Maryland Baltimore, Baltimore, MD, USA
| | - Hanping Feng
- Department of Microbial Pathogenesis, University of Maryland Baltimore, Baltimore, MD, USA
| | - Tsutomu Matsui
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA
| | - Mark E Bowen
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL, USA
| | - Rongsheng Jin
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, USA.
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5
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Chandrasekaran R, Lacy DB. The role of toxins in Clostridium difficile infection. FEMS Microbiol Rev 2017; 41:723-750. [PMID: 29048477 PMCID: PMC5812492 DOI: 10.1093/femsre/fux048] [Citation(s) in RCA: 210] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 10/10/2017] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile is a bacterial pathogen that is the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. The incidence, severity, mortality and healthcare costs associated with C. difficile infection (CDI) are rising, making C. difficile a major threat to public health. Traditional treatments for CDI involve use of antibiotics such as metronidazole and vancomycin, but disease recurrence occurs in about 30% of patients, highlighting the need for new therapies. The pathogenesis of C. difficile is primarily mediated by the actions of two large clostridial glucosylating toxins, toxin A (TcdA) and toxin B (TcdB). Some strains produce a third toxin, the binary toxin C. difficile transferase, which can also contribute to C. difficile virulence and disease. These toxins act on the colonic epithelium and immune cells and induce a complex cascade of cellular events that result in fluid secretion, inflammation and tissue damage, which are the hallmark features of the disease. In this review, we summarize our current understanding of the structure and mechanism of action of the C. difficile toxins and their role in disease.
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Affiliation(s)
- Ramyavardhanee Chandrasekaran
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - D. Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- The Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37232, USA
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6
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Di Bella S, Ascenzi P, Siarakas S, Petrosillo N, di Masi A. Clostridium difficile Toxins A and B: Insights into Pathogenic Properties and Extraintestinal Effects. Toxins (Basel) 2016; 8:E134. [PMID: 27153087 PMCID: PMC4885049 DOI: 10.3390/toxins8050134] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 02/06/2023] Open
Abstract
Clostridium difficile infection (CDI) has significant clinical impact especially on the elderly and/or immunocompromised patients. The pathogenicity of Clostridium difficile is mainly mediated by two exotoxins: toxin A (TcdA) and toxin B (TcdB). These toxins primarily disrupt the cytoskeletal structure and the tight junctions of target cells causing cell rounding and ultimately cell death. Detectable C. difficile toxemia is strongly associated with fulminant disease. However, besides the well-known intestinal damage, recent animal and in vitro studies have suggested a more far-reaching role for these toxins activity including cardiac, renal, and neurologic impairment. The creation of C. difficile strains with mutations in the genes encoding toxin A and B indicate that toxin B plays a major role in overall CDI pathogenesis. Novel insights, such as the role of a regulator protein (TcdE) on toxin production and binding interactions between albumin and C. difficile toxins, have recently been discovered and will be described. Our review focuses on the toxin-mediated pathogenic processes of CDI with an emphasis on recent studies.
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Affiliation(s)
- Stefano Di Bella
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Rome 00149, Italy.
| | - Paolo Ascenzi
- Department of Science, Roma Tre University, Rome 00154, Italy.
| | - Steven Siarakas
- Department of Microbiology and Infectious Diseases, Concord Repatriation General Hospital, Sydney 2139, Australia.
| | - Nicola Petrosillo
- 2nd Infectious Diseases Division, National Institute for Infectious Diseases "L. Spallanzani", Rome 00149, Italy.
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7
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Varela Chavez C, Haustant GM, Baron B, England P, Chenal A, Pauillac S, Blondel A, Popoff MR. The Tip of the Four N-Terminal α-Helices of Clostridium sordellii Lethal Toxin Contains the Interaction Site with Membrane Phosphatidylserine Facilitating Small GTPases Glucosylation. Toxins (Basel) 2016; 8:90. [PMID: 27023605 PMCID: PMC4848617 DOI: 10.3390/toxins8040090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/01/2016] [Accepted: 03/10/2016] [Indexed: 12/22/2022] Open
Abstract
Clostridium sordellii lethal toxin (TcsL) is a powerful virulence factor responsible for severe toxic shock in man and animals. TcsL belongs to the large clostridial glucosylating toxin (LCGT) family which inactivates small GTPases by glucosylation with uridine-diphosphate (UDP)-glucose as a cofactor. Notably, TcsL modifies Rac and Ras GTPases, leading to drastic alteration of the actin cytoskeleton and cell viability. TcsL enters cells via receptor-mediated endocytosis and delivers the N-terminal glucosylating domain (TcsL-cat) into the cytosol. TcsL-cat was found to preferentially bind to phosphatidylserine (PS)-containing membranes and to increase the glucosylation of Rac anchored to the lipid membrane. We have previously reported that the N-terminal four helical bundle structure (1–93 domain) recognizes a broad range of lipids, but that TcsL-cat specifically binds to PS and phosphatidic acid. Here, we show using mutagenesis that the PS binding site is localized on the tip of the four-helix bundle which is rich in positively-charged amino acids. Residues Y14, V15, F17, and R18 on loop 1, between helices 1 and 2, in coordination with R68 from loop 3, between helices 3 and 4, form a pocket which accommodates L-serine. The functional PS-binding site is required for TcsL-cat binding to the plasma membrane and subsequent cytotoxicity. TcsL-cat binding to PS facilitates a high enzymatic activity towards membrane-anchored Ras by about three orders of magnitude as compared to Ras in solution. The PS-binding site is conserved in LCGTs, which likely retain a common mechanism of binding to the membrane for their full activity towards membrane-bound GTPases.
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Affiliation(s)
- Carolina Varela Chavez
- Unité des Bactéries anaérobies et Toxines, Institut Pasteur, 75724 Paris cedex15, France.
| | | | - Bruno Baron
- Plate-Forme de Biophysique Moléculaires, Institut Pasteur, 75724 Paris cedex15, France.
| | - Patrick England
- Plate-Forme de Biophysique Moléculaires, Institut Pasteur, 75724 Paris cedex15, France.
| | - Alexandre Chenal
- Unité de Biochimie des Interactions Macromoléculaires, Institut Pasteur, 75724 Paris cedex15, France.
| | - Serge Pauillac
- Unité des Bactéries anaérobies et Toxines, Institut Pasteur, 75724 Paris cedex15, France.
| | - Arnaud Blondel
- Unité de Bioinformatique Structurale, Institut Pasteur, 75724 Paris cedex15, France.
| | - Michel-Robert Popoff
- Unité des Bactéries anaérobies et Toxines, Institut Pasteur, 75724 Paris cedex15, France.
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8
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Abstract
The virulence of highly pathogenic bacteria such as Salmonella, Yersinia, Staphylococci, Clostridia, and pathogenic strains of Escherichia coli involves intimate cross-talks with the host actin cytoskeleton and its upstream regulators. A large number of virulence factors expressed by these pathogens modulate Rho GTPase activities either by mimicking cellular regulators or by catalyzing posttranslational modifications of these small proteins. This impressive convergence of virulence toward Rho GTPases and actin indeed offers pathogens the capacity to breach host defenses and invade their host, while it promotes inflammatory reactions. In return, the study of this targeting of Rho GTPases in infection has been an invaluable source of information in cell signaling, cell biology, and biomechanics, as well as in immunology. Through selected examples, I highlight the importance of recent studies on this crosstalk, which have unveiled new mechanisms of regulation of Rho GTPases; the relationship between cell shape and actin cytoskeleton organization; and the relationship between Rho GTPases and innate immune signaling.
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Affiliation(s)
- Emmanuel Lemichez
- UCA, Inserm, C3M, U1065, Team Microbial Toxins in Host Pathogen Interactions, Equipe Labellisée la Ligue Contre le Cancer, Nice, 06204, France.
- UFR Médecine, Université de Nice-Sophia-Antipolis, Nice, France.
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9
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Gerhard R. Receptors and Binding Structures for Clostridium difficile Toxins A and B. Curr Top Microbiol Immunol 2016; 406:79-96. [PMID: 27380268 DOI: 10.1007/82_2016_17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two characteristics of toxins A and B from C. difficile (TcdA, TcdB) are important for the understanding of the pathogenic effect of these homologous toxins. First, these toxins are huge single-chain but multidomain proteins that display their action intracellularly within the cytosol of host cells. And second, albeit various cell types highly differ in their sensitivity toward these toxins, no toxin-resistant cell type has been described yet. Investigation of receptor-mediated uptake of these toxins is very ambitious. It demands discrimination between cell surface binding, interaction with more than one functional receptor responsible for uptake as well as other functional receptors that recognize bacterial pathogens and are not necessarily related with endocytosis. The current understanding of a complex uptake process is that TcdB interacts with at least two facultative receptors that mediate entry into host cells by redundant endocytotic pathways. Although both homologous toxins do obviously not share the same receptors, this principle of redundant binding domains found for TcdB does also account for TcdA.
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Affiliation(s)
- Ralf Gerhard
- Institut für Toxikologie, Medizinische Hochschule, Hannover, Germany.
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10
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Clostridium sordellii Lethal-Toxin Autoprocessing and Membrane Localization Activities Drive GTPase Glucosylation Profiles in Endothelial Cells. mSphere 2015; 1:mSphere00012-15. [PMID: 27303685 PMCID: PMC4863631 DOI: 10.1128/msphere.00012-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 11/05/2015] [Indexed: 11/20/2022] Open
Abstract
Clostridium sordellii is a bacterium that can infect humans and cause serious disease and death. The principle virulence factor associated with clinical symptoms is a large protein toxin known as lethal toxin. The mechanism of lethal-toxin intoxication is assumed to be similar to that of the homologous toxins from C. difficile, but very few studies have been done in the context of endothelial cells, a relevant target in C. sordellii infections. This study was designed to test the role of the lethal-toxin enzymatic activities and membrane localization in endothelial cell toxicity and host substrate modification. Clostridium sordellii infections cause gangrene and edema in humans and gastrointestinal infections in livestock. One of the principle virulence factors is TcsL, a large protein toxin which glucosylates host GTPases to cause cytopathic and cytotoxic effects. TcsL has two enzymatic domains, an N-terminal glucosyltransferase domain (GTD) and an autoprocessing domain responsible for release of the GTD within the cell. The GTD can then use its N-terminal membrane localization domain (MLD) for orientation on membranes and modification of GTPases. This study describes the use of conditionally immortalized murine pulmonary microvascular endothelial cells as a model for the study of TcsL functional activities. Point mutations that disrupt the glucosyltransferase, autoprocessing, or membrane localization activities were introduced into a recombinant version of TcsL, and the activities of these mutants were compared to those of wild-type toxin. We observed that all mutants are defective or impaired in cytotoxicity but differ in their modification of Rac1 and Ras. The data suggest a model where differences in GTPase localization dictate cellular responses to intoxication and highlight the importance of autoprocessing in the function of TcsL. IMPORTANCEClostridium sordellii is a bacterium that can infect humans and cause serious disease and death. The principle virulence factor associated with clinical symptoms is a large protein toxin known as lethal toxin. The mechanism of lethal-toxin intoxication is assumed to be similar to that of the homologous toxins from C. difficile, but very few studies have been done in the context of endothelial cells, a relevant target in C. sordellii infections. This study was designed to test the role of the lethal-toxin enzymatic activities and membrane localization in endothelial cell toxicity and host substrate modification.
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11
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The phospholipid code: a key component of dying cell recognition, tumor progression and host-microbe interactions. Cell Death Differ 2015; 22:1893-905. [PMID: 26450453 DOI: 10.1038/cdd.2015.122] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 02/06/2023] Open
Abstract
A significant effort is made by the cell to maintain certain phospholipids at specific sites. It is well described that proteins involved in intracellular signaling can be targeted to the plasma membrane and organelles through phospholipid-binding domains. Thus, the accumulation of a specific combination of phospholipids, denoted here as the 'phospholipid code', is key in initiating cellular processes. Interestingly, a variety of extracellular proteins and pathogen-derived proteins can also recognize or modify phospholipids to facilitate the recognition of dying cells, tumorigenesis and host-microbe interactions. In this article, we discuss the importance of the phospholipid code in a range of physiological and pathological processes.
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12
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Varela Chavez C, Hoos S, Haustant GM, Chenal A, England P, Blondel A, Pauillac S, Lacy DB, Popoff MR. The catalytic domains of Clostridium sordellii lethal toxin and related large clostridial glucosylating toxins specifically recognize the negatively charged phospholipids phosphatidylserine and phosphatidic acid. Cell Microbiol 2015; 17:1477-93. [PMID: 25882477 DOI: 10.1111/cmi.12449] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/15/2015] [Indexed: 12/23/2022]
Abstract
Clostridium sordellii lethal toxin (TcsL) is a potent virulence factor belonging to the large clostridial glucosylating toxin family. TcsL enters target cells via receptor-mediated endocytosis and delivers the N-terminal catalytic domain (TcsL-cat) into the cytosol upon an autoproteolytic process. TcsL-cat inactivates small GTPases including Rac and Ras by glucosylation with uridine-diphosphate (UDP)-glucose as cofactor leading to drastic changes in cytoskeleton and cell viability. TcsL-cat was found to preferentially bind to phosphatidylserine (PS)-containing membranes and to increase the glucosylation of Rac anchored to lipid membrane. We here report binding affinity measurements of TcsL-cat for brain PS-containing membranes by surface plasmon resonance and enzyme-linked immunosorbent assay (ELISA). In addition, TcsL-cat bound to phosphatidic acid (PA) and, to a lesser extent, to other anionic lipids, but not to neutral lipids, sphingolipids or sterol. We further show that the lipid unsaturation status influenced TcsL-cat binding to phospholipids, PS with unsaturated acyl chains and PA with saturated acyl chains being the preferred bindingsubstrates. Phospholipid binding site is localized at the N-terminal four helical bundle structure (1-93 domain). However, TcsL-1-93 bound to a broad range of substrates, whereas TcsL-cat, which is the active domain physiologically delivered into the cytosol, selectively bound to PS and PA. Similar findings were observed with the other large clostridial glucosylating toxins from C. difficile, C. novyi and C. perfringens.
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Affiliation(s)
| | - Sylviane Hoos
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | | | - Alexandre Chenal
- Unité de Biochimie des Interactions Macromoléculaires, Institut Pasteur, Paris, France
| | - Patrick England
- Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France
| | - Arnaud Blondel
- Unité de Bioinformatique Structurale, Institut Pasteur, Paris, France
| | - Serge Pauillac
- Unité des Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France
| | - D Borden Lacy
- Unité de Bioinformatique Structurale, Institut Pasteur, Paris, France.,Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
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13
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Jank T, Trillhaase C, Brozda N, Steinemann M, Schwan C, Süss R, Aktories K. Intracellular plasma membrane guidance of
Photorhabdus asymbiotica
toxin is crucial for cell toxicity. FASEB J 2015; 29:2789-802. [DOI: 10.1096/fj.14-269381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/26/2015] [Indexed: 01/06/2023]
Affiliation(s)
- Thomas Jank
- Departments of Experimental and Clinical Pharmacology and ToxicologyUniversity of FreiburgFreiburgGermany
| | - Christoph Trillhaase
- Departments of Experimental and Clinical Pharmacology and ToxicologyUniversity of FreiburgFreiburgGermany
| | - Natalia Brozda
- Departments of Experimental and Clinical Pharmacology and ToxicologyUniversity of FreiburgFreiburgGermany
| | - Marcus Steinemann
- Departments of Experimental and Clinical Pharmacology and ToxicologyUniversity of FreiburgFreiburgGermany
| | - Carsten Schwan
- Departments of Experimental and Clinical Pharmacology and ToxicologyUniversity of FreiburgFreiburgGermany
| | - Regine Süss
- Pharmaceutical Technology and BiopharmacyUniversity of FreiburgFreiburgGermany
| | - Klaus Aktories
- Departments of Experimental and Clinical Pharmacology and ToxicologyUniversity of FreiburgFreiburgGermany
- Centre for Biological Signalling Studies, University of FreiburgFreiburgGermany
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14
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Tyson GH, Halavaty AS, Kim H, Geissler B, Agard M, Satchell KJ, Cho W, Anderson WF, Hauser AR. A novel phosphatidylinositol 4,5-bisphosphate binding domain mediates plasma membrane localization of ExoU and other patatin-like phospholipases. J Biol Chem 2014; 290:2919-37. [PMID: 25505182 DOI: 10.1074/jbc.m114.611251] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacterial toxins require localization to specific intracellular compartments following injection into host cells. In this study, we examined the membrane targeting of a broad family of bacterial proteins, the patatin-like phospholipases. The best characterized member of this family is ExoU, an effector of the Pseudomonas aeruginosa type III secretion system. Upon injection into host cells, ExoU localizes to the plasma membrane, where it uses its phospholipase A2 activity to lyse infected cells. The targeting mechanism of ExoU is poorly characterized, but it was recently found to bind to the phospholipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a marker for the plasma membrane of eukaryotic cells. We confirmed that the membrane localization domain (MLD) of ExoU had a direct affinity for PI(4,5)P2, and we determined that this binding was required for ExoU localization. Previously uncharacterized ExoU homologs from Pseudomonas fluorescens and Photorhabdus asymbiotica also localized to the plasma membrane and required PI(4,5)P2 for this localization. A conserved arginine within the MLD was critical for interaction of each protein with PI(4,5)P2 and for localization. Furthermore, we determined the crystal structure of the full-length P. fluorescens ExoU and found that it was similar to that of P. aeruginosa ExoU. Each MLD contains a four-helical bundle, with the conserved arginine exposed at its cap to allow for interaction with the negatively charged PI(4,5)P2. Overall, these findings provide a structural explanation for the targeting of patatin-like phospholipases to the plasma membrane and define the MLD of ExoU as a member of a new class of PI(4,5)P2 binding domains.
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Affiliation(s)
| | - Andrei S Halavaty
- Biochemistry and Center for Structural Genomics of Infectious Diseases, Northwestern University, Chicago, Illinois 60611 and
| | - Hyunjin Kim
- the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | | | | | | | - Wonhwa Cho
- the Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607
| | - Wayne F Anderson
- Biochemistry and Center for Structural Genomics of Infectious Diseases, Northwestern University, Chicago, Illinois 60611 and
| | - Alan R Hauser
- From the Departments of Microbiology-Immunology, Medicine, and
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15
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Bigay J, Antonny B. Curvature, lipid packing, and electrostatics of membrane organelles: defining cellular territories in determining specificity. Dev Cell 2013; 23:886-95. [PMID: 23153485 DOI: 10.1016/j.devcel.2012.10.009] [Citation(s) in RCA: 358] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Whereas some rare lipids contribute to the identity of cell organelles, we focus on the abundant lipids that form the matrix of organelle membranes. Observations using bioprobes and peripheral proteins, notably sensors of membrane curvature, support the prediction that the cell contains two broad membrane territories: the territory of loose lipid packing, where cytosolic proteins take advantage of membrane defects, and the territory of electrostatics, where proteins are attracted by negatively charged lipids. The contrasting features of these territories provide specificity for reactions occurring along the secretory pathway, on the plasma membrane, and also on lipid droplets and autophagosomes.
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Affiliation(s)
- Joëlle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia Antipolis et CNRS, 06560 Valbonne, France
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16
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Singh MK, Ren F, Giesemann T, Dal Bosco C, Pasternak TP, Blein T, Ruperti B, Schmidt G, Aktories K, Molendijk AJ, Palme K. Modification of plant Rac/Rop GTPase signalling using bacterial toxin transgenes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:314-24. [PMID: 23020817 DOI: 10.1111/tpj.12040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 09/20/2012] [Accepted: 09/27/2012] [Indexed: 05/23/2023]
Abstract
Bacterial protein toxins which modify Rho GTPase are useful for the analysis of Rho signalling in animal cells, but these toxins cannot be taken up by plant cells. We demonstrate in vitro deamidation of Arabidopsis Rop4 by Escherichia coli Cytotoxic Necrotizing Factor 1 (CNF1) and glucosylation by Clostridium difficile toxin B. Expression of the catalytic domain of CNF1 caused modification and activation of co-expressed Arabidopsis Rop4 GTPase in tobacco leaves, resulting in hypersensitive-like cell death. By contrast, the catalytic domain of toxin B modified and inactivated co-expressed constitutively active Rop4, blocking the hypersensitive response caused by over-expression of active Rops. In transgenic Arabidopsis, both CNF1 and toxin B inhibited Rop-dependent polar morphogenesis of leaf epidermal cells. Toxin B expression also inhibited Rop-dependent morphogenesis of root hairs and trichome branching, and resulted in root meristem enlargement and dwarf growth. Our results show that CNF1 and toxin B transgenes are effective tools in Rop GTPase signalling studies.
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Affiliation(s)
- Manoj K Singh
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Fugang Ren
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Torsten Giesemann
- Institute for Clinical and Experimental Pharmacology and Toxicology, Albert-Ludwigs-University of Freiburg, Albertstrasse 25, 79104, Freiburg, Germany
| | - Cristina Dal Bosco
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Taras P Pasternak
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Thomas Blein
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Benedetto Ruperti
- Department of Environmental Agronomy and Crop Science, University of Padova, Via Romea, 16, Agripolis, 35020, Legnaro, Padova, Italy
| | - Gudula Schmidt
- Institute for Clinical and Experimental Pharmacology and Toxicology, Albert-Ludwigs-University of Freiburg, Albertstrasse 25, 79104, Freiburg, Germany
| | - Klaus Aktories
- Institute for Clinical and Experimental Pharmacology and Toxicology, Albert-Ludwigs-University of Freiburg, Albertstrasse 25, 79104, Freiburg, Germany
| | - Arthur J Molendijk
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
- Freiburg Initiative for Systems Biology (FRISYS), Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Klaus Palme
- Faculty of Biology, Institute for Biology II/Botany, Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
- Freiburg Initiative for Systems Biology (FRISYS), Albert-Ludwigs-University of Freiburg, Schänzlestrasse 1, 79104, Freiburg, Germany
- Centre of Biological Systems Analysis, Albert-Ludwigs-University of Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany
- Freiburg Institute for Advanced Sciences (FRIAS), Albert-Ludwigs-University of Freiburg, Albertstrasse 19, 79104, Freiburg, Germany
- Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University of Freiburg, Albertstrasse 19, 79104, Freiburg, Germany
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17
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Geissler B. Bacterial toxin effector-membrane targeting: outside in, then back again. Front Cell Infect Microbiol 2012; 2:75. [PMID: 22919666 PMCID: PMC3417404 DOI: 10.3389/fcimb.2012.00075] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/14/2012] [Indexed: 01/20/2023] Open
Abstract
Pathogenic bacteria utilize multiple approaches to establish infection and mediate their toxicity to eukaryotic cells. Dedicated protein machines deposit toxic effectors directly inside the host, whereas secreted toxins must enter cells independently of other bacterial components. Regardless of how they reach the cytosol, these bacterial proteins must accurately identify their intracellular target before they can manipulate the host cell to benefit their associated bacteria. Within eukaryotic cells, post-translational modifications and individual targeting motifs spatially regulate endogenous host proteins. This review focuses on the strategies employed by bacterial effectors to associate with a frequently targeted location within eukaryotic cells, the plasma membrane.
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Affiliation(s)
- Brett Geissler
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA.
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18
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Pruitt RN, Lacy DB. Toward a structural understanding of Clostridium difficile toxins A and B. Front Cell Infect Microbiol 2012; 2:28. [PMID: 22919620 PMCID: PMC3417631 DOI: 10.3389/fcimb.2012.00028] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 02/27/2012] [Indexed: 12/17/2022] Open
Abstract
Clostridium difficile is a toxin-producing bacterium that is a frequent cause of hospital-acquired and antibiotic-associated diarrhea. The incidence, severity, and costs associated with C. difficile associated disease are substantial and increasing, making C. difficile a significant public health concern. The two primary toxins, TcdA and TcdB, disrupt host cell function by inactivating small GTPases that regulate the actin cytoskeleton. This review will discuss the role of these two toxins in pathogenesis and the structural and molecular mechanisms by which they intoxicate cells. A focus will be placed on recent publications highlighting mechanistic similarities and differences between TcdA, TcdB, and different TcdB variants.
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Affiliation(s)
- Rory N Pruitt
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville TN, USA
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19
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Pruitt RN, Chumbler NM, Rutherford SA, Farrow MA, Friedman DB, Spiller B, Lacy DB. Structural determinants of Clostridium difficile toxin A glucosyltransferase activity. J Biol Chem 2012; 287:8013-20. [PMID: 22267739 DOI: 10.1074/jbc.m111.298414] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The principle virulence factors in Clostridium difficile pathogenesis are TcdA and TcdB, homologous glucosyltransferases capable of inactivating small GTPases within the host cell. We present crystal structures of the TcdA glucosyltransferase domain in the presence and absence of the co-substrate UDP-glucose. Although the enzymatic core is similar to that of TcdB, the proposed GTPase-binding surface differs significantly. We show that TcdA is comparable with TcdB in its modification of Rho family substrates and that, unlike TcdB, TcdA is also capable of modifying Rap family GTPases both in vitro and in cells. The glucosyltransferase activities of both toxins are reduced in the context of the holotoxin but can be restored with autoproteolytic activation and glucosyltransferase domain release. These studies highlight the importance of cellular activation in determining the array of substrates available to the toxins once delivered into the cell.
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Affiliation(s)
- Rory N Pruitt
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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20
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Abstract
All bacterial toxins, which globally are hydrophilic proteins, interact first with their target cells by recognizing a surface receptor, which is either a lipid or a lipid derivative, or another compound but in a lipid environment. Intracellular active toxins follow various trafficking pathways, the sorting of which is greatly dependent on the nature of the receptor, notably lipidic receptor or receptor embedded into a distinct environment such as lipid microdomains. Numerous other toxins act locally on cell membrane. Indeed, phospholipase activity is a common mechanism shared by several membrane-damaging toxins. In addition, many toxins active intracellularly or on cell membrane modulate host cell phospholipid pathways. Unusually, a few bacterial toxins require a lipid post-translational modification to be active. Thereby, lipids are obligate partners of bacterial toxins.
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Affiliation(s)
- Blandine Geny
- Unité des Bactéries Anaérobies et Toxines, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris cedex 15, France
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21
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Geissler B, Ahrens S, Satchell KJF. Plasma membrane association of three classes of bacterial toxins is mediated by a basic-hydrophobic motif. Cell Microbiol 2011; 14:286-98. [PMID: 22044757 DOI: 10.1111/j.1462-5822.2011.01718.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Plasma membrane targeting is essential for the proper function of many bacterial toxins. A conserved fourhelical bundle membrane localization domain (4HBM) was recently identified within three diverse families of toxins: clostridial glucosylating toxins, MARTX toxins and Pasteurella multocida-like toxins. When expressed in tissue culture cells or in yeast, GFP fusions to at least one 4HBM from each toxin family show significant peripheral membrane localization but with differing profiles. Both in vivo expression and in vitro binding studies reveal that the ability of these domains to localize to the plasma membrane and bind negatively charged phospholipids requires a basic-hydrophobic motif formed by the L1 and L3 loops. The different binding capacity of each 4HBM is defined by the hydrophobicity of an exposed residue within the motif. This study establishes that bacterial effectors utilize a normal host cell mechanism to locate the plasma membrane where they can then access their intracellular targets.
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Affiliation(s)
- Brett Geissler
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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22
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Satchell KJ. Structure and Function of MARTX Toxins and Other Large Repetitive RTX Proteins. Annu Rev Microbiol 2011; 65:71-90. [DOI: 10.1146/annurev-micro-090110-102943] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Karla J.F. Satchell
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611;
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23
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Belyi Y, Jank T, Aktories K. Effector glycosyltransferases in legionella. Front Microbiol 2011; 2:76. [PMID: 21833323 PMCID: PMC3153043 DOI: 10.3389/fmicb.2011.00076] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 03/31/2011] [Indexed: 11/13/2022] Open
Abstract
Legionella causes severe pneumonia in humans. The pathogen produces an array of effectors, which interfere with host cell functions. Among them are the glucosyltransferases Lgt1, Lgt2 and Lgt3 from L. pneumophila. Lgt1 and Lgt2 are produced predominately in the post-exponential phase of bacterial growth, while synthesis of Lgt3 is induced mainly in the lag-phase before intracellular replication of bacteria starts. Lgt glucosyltransferases are structurally similar to clostridial glucosylating toxins. The enzymes use UDP–glucose as a donor substrate and modify eukaryotic elongation factor eEF1A at serine-53. This modification results in inhibition of protein synthesis and death of target cells.In addition to Lgts, Legionella genomes disclose several genes, coding for effector proteins likely to possess glycosyltransferase activities, including SetA (subversion of eukaryotic vesicle trafficking A), which influences vesicular trafficking in the yeast model system and displays tropism for late endosomal/lysosomal compartments of mammalian cells. This review mainly discusses recent results on the structure–function relationship of Lgt glucosyltransferases.
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Affiliation(s)
- Yury Belyi
- Gamaleya Research Institute Moscow, Russia
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24
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Kamitani S, Kitadokoro K, Miyazawa M, Toshima H, Fukui A, Abe H, Miyake M, Horiguchi Y. Characterization of the membrane-targeting C1 domain in Pasteurella multocida toxin. J Biol Chem 2010; 285:25467-75. [PMID: 20534589 DOI: 10.1074/jbc.m110.102285] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Pasteurella multocida toxin (PMT) is a virulence factor responsible for the pathogenesis of some forms of pasteurellosis. The toxin activates G(q)- and G(12/13)-dependent pathways through the deamidation of a glutamine residue in the alpha-subunit of heterotrimeric GTPases. We recently reported the crystal structure of the C terminus (residues 575-1285) of PMT (C-PMT), which is composed of three domains (C1, C2, and C3), and that the C1 domain is involved in the localization of C-PMT to the plasma membrane, and the C3 domain possesses a cysteine protease-like catalytic triad. In this study, we analyzed the membrane-targeting function of the C1 domain in detail. The C1 domain consists of seven helices of which the first four (residues 590-670), showing structural similarity to the N terminus of Clostridium difficile toxin B, were found to be involved in the recruitment of C-PMT to the plasma membrane. C-PMT lacking these helices (C-PMT DeltaC1(4H)) neither localized to the plasma membrane nor stimulated the G(q/12/13)-dependent signaling pathways. When the membrane-targeting property was complemented by a peptide tag with an N-myristoylation motif, C-PMT DeltaC1(4H) recovered the PMT activity. Direct binding between the C1 domain and liposomes containing phospholipids was evidenced by surface plasmon resonance analyses. These results indicate that the C1 domain of C-PMT functions as a targeting signal for the plasma membrane.
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Affiliation(s)
- Shigeki Kamitani
- Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita-shi, Osaka 565-0871, Japan.
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25
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Identification of a conserved membrane localization domain within numerous large bacterial protein toxins. Proc Natl Acad Sci U S A 2010; 107:5581-6. [PMID: 20212166 DOI: 10.1073/pnas.0908700107] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Vibrio cholerae is the causative agent of the diarrheal disease cholera. Many virulence factors contribute to intestinal colonization and disease including the Multifunctional Autoprocessing RTX toxin (MARTX(Vc)). The Rho-inactivation domain (RID) of MARTX(Vc) is responsible for inactivating the Rho-family of small GTPases, which leads to depolymerization of the actin cytoskeleton. Based on a deletion analysis of RID to determine the minimal functional domain, we have identified a subdomain at the N terminus of RID that is homologous to the membrane targeting C1 domain of Pasteurella multocida toxin. A GFP fusion to this subdomain from RID colocalized with a plasma membrane marker when transiently expressed within HeLa cells and can be found in the membrane fraction following subcellular fractionation. This C1-like subdomain is present in multiple families of bacterial toxins, including all of the clostridial glucosyltransferase toxins and various MARTX toxins. GFP-fusions to these homologous domains are also membrane associated, indicating that this is a conserved membrane localization domain (MLD). We have identified three residues (Y23, S68, R70) as necessary for proper localization of one but not all MLDs. In addition, we found that substitution of the RID MLD with the MLDs from two different effector domains from the Vibrio vulnificus MARTX toxin restored RID activity, indicating that there is functional overlap between these MLDs. This study describes the initial recognition of a family of conserved plasma membrane-targeting domains found in multiple large bacterial toxins.
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26
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Belyi Y, Aktories K. Bacterial toxin and effector glycosyltransferases. Biochim Biophys Acta Gen Subj 2010; 1800:134-43. [DOI: 10.1016/j.bbagen.2009.07.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 07/14/2009] [Accepted: 07/18/2009] [Indexed: 02/08/2023]
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27
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Abstract
Clostridia produce the highest number of toxins of any type of bacteria and are involved in severe diseases in humans and other animals. Most of the clostridial toxins are pore-forming toxins responsible for gangrenes and gastrointestinal diseases. Among them, perfringolysin has been extensively studied and it is the paradigm of the cholesterol-dependent cytolysins, whereas Clostridium perfringens epsilon-toxin and Clostridium septicum alpha-toxin, which are related to aerolysin, are the prototypes of clostridial toxins that form small pores. Other toxins active on the cell surface possess an enzymatic activity, such as phospholipase C and collagenase, and are involved in the degradation of specific cell-membrane or extracellular-matrix components. Three groups of clostridial toxins have the ability to enter cells: large clostridial glucosylating toxins, binary toxins and neurotoxins. The binary and large clostridial glucosylating toxins alter the actin cytoskeleton by enzymatically modifying the actin monomers and the regulatory proteins from the Rho family, respectively. Clostridial neurotoxins proteolyse key components of neuroexocytosis. Botulinum neurotoxins inhibit neurotransmission at neuromuscular junctions, whereas tetanus toxin targets the inhibitory interneurons of the CNS. The high potency of clostridial toxins results from their specific targets, which have an essential cellular function, and from the type of modification that they induce. In addition, clostridial toxins are useful pharmacological and biological tools.
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Affiliation(s)
- Michel R Popoff
- Institut Pasteur, Bactéries Anaérobies et Toxines, 75724 Paris cedex 15, France.
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28
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Geny B, Popoff MR. Activation of a c-Jun-NH2-terminal kinase pathway by the lethal toxin fromClostridium sordellii, TcsL-82, occurs independently of the toxin intrinsic enzymatic activity and facilitates small GTPase glucosylation. Cell Microbiol 2009; 11:1102-13. [DOI: 10.1111/j.1462-5822.2009.01314.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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29
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Abramovici H, Mojtabaie P, Parks RJ, Zhong XP, Koretzky GA, Topham MK, Gee SH. Diacylglycerol kinase zeta regulates actin cytoskeleton reorganization through dissociation of Rac1 from RhoGDI. Mol Biol Cell 2009; 20:2049-59. [PMID: 19211846 DOI: 10.1091/mbc.e07-12-1248] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Activation of Rac1 GTPase signaling is stimulated by phosphorylation and release of RhoGDI by the effector p21-activated kinase 1 (PAK1), but it is unclear what initiates this potential feed-forward mechanism for regulation of Rac activity. Phosphatidic acid (PA), which is produced from the lipid second messenger diacylglycerol (DAG) by the action of DAG kinases (DGKs), is known to activate PAK1. Here, we investigated whether PA produced by DGKzeta initiates RhoGDI release and Rac1 activation. In DGKzeta-deficient fibroblasts PAK1 phosphorylation and Rac1-RhoGDI dissociation were attenuated, leading to reduced Rac1 activation after platelet-derived growth factor stimulation. The cells were defective in Rac1-regulated behaviors, including lamellipodia formation, membrane ruffling, migration, and spreading. Wild-type DGKzeta, but not a kinase-dead mutant, or addition of exogenous PA rescued Rac activation. DGKzeta stably associated with PAK1 and RhoGDI, suggesting these proteins form a complex that functions as a Rac1-selective RhoGDI dissociation factor. These results define a pathway that links diacylglycerol, DGKzeta, and PA to the activation of Rac1: the PA generated by DGKzeta activates PAK1, which dissociates RhoGDI from Rac1 leading to changes in actin dynamics that facilitate the changes necessary for cell motility.
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Affiliation(s)
- Hanan Abramovici
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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30
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Jank T, Aktories K. Structure and mode of action of clostridial glucosylating toxins: the ABCD model. Trends Microbiol 2008; 16:222-9. [PMID: 18394902 DOI: 10.1016/j.tim.2008.01.011] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 12/21/2007] [Accepted: 01/21/2008] [Indexed: 10/22/2022]
Abstract
Toxins A and B, which are the major virulence factors of antibiotic-associated diarrhea and pseudomembranous colitis caused by Clostridium difficile, are the prototypes of the family of clostridial glucosylating toxins. The toxins inactivate Rho and Ras proteins by glucosylation. Recent findings on the autocatalytic processing of the toxins and analysis of the crystal structures of their domains have made a revision of the current model of their actions on the eukaryotic target cells necessary.
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Affiliation(s)
- Thomas Jank
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Otto-Krayer-Haus, Albertstrasse 25, D-79104 Freiburg, Germany
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31
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Ziegler MOP, Jank T, Aktories K, Schulz GE. Conformational changes and reaction of clostridial glycosylating toxins. J Mol Biol 2008; 377:1346-56. [PMID: 18325534 DOI: 10.1016/j.jmb.2007.12.065] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 12/19/2007] [Accepted: 12/22/2007] [Indexed: 11/19/2022]
Abstract
The crystal structures of the catalytic fragments of 'lethal toxin' from Clostridium sordellii and of 'alpha-toxin' from Clostridium novyi have been established. Almost half of the residues follow the chain fold of the glycosyl-transferase type A family of enzymes; the other half forms large alpha-helical protrusions that are likely to confer specificity for the respective targeted subgroup of Rho proteins in the cell. In the crystal, the active center of alpha-toxin contained no substrates and was disassembled, whereas that of lethal toxin, which was ligated with the donor substrate UDP-glucose and cofactor Mn2+, was catalytically competent. Surprisingly, the structure of lethal toxin with Ca2+ (instead of Mn2+) at the cofactor position showed a bound donor substrate with a disassembled active center, indicating that the strictly octahedral coordination sphere of Mn2+ is indispensable to the integrity of the enzyme. The homologous structures of alpha-toxin without substrate, distorted lethal toxin with Ca2+ plus donor, active lethal toxin with Mn2+ plus donor and the homologous Clostridium difficile toxin B with a hydrolyzed donor have been lined up to show the geometry of several reaction steps. Interestingly, the structural refinement of one of the three crystallographically independent molecules of Ca2+-ligated lethal toxin resulted in the glucosyl half-chair conformation expected for glycosyl-transferases that retain the anomeric configuration at the C1'' atom. A superposition of six acceptor substrates bound to homologous enzymes yielded the position of the nucleophilic acceptor atom with a deviation of <1 A. The resulting donor-acceptor geometry suggests that the reaction runs as a circular electron transfer in a six-membered ring, which involves the deprotonation of the nucleophile by the beta-phosphoryl group of the donor substrate UDP-glucose.
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Affiliation(s)
- Mathias O P Ziegler
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstr. 21, D-79104 Freiburg im Breisgau, Germany
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32
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Voth DE, Ballard JD. Critical intermediate steps in Clostridium sordellii lethal toxin-induced apoptosis. Biochem Biophys Res Commun 2007; 363:959-64. [PMID: 17910886 DOI: 10.1016/j.bbrc.2007.09.073] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Accepted: 09/19/2007] [Indexed: 11/26/2022]
Abstract
Clostridium sordellii lethal toxin (TcsL) inactivates small GTPases via glucosylation and induces apoptosis in mammalian cells; however, signaling events that link substrate modification with modulation of the mitochondria in these cells has not been determined. Experiments in the current study examined TcsL modulation of the Akt signaling pathway and related downstream targets. Early in TcsL intoxication, cells demonstrated a dramatic decrease in phosphorylated Akt, and this event required toxin enzymatic activity. The decrease in phosphorylated Akt was followed by caspase-dependent processing of Bcl-x(L) and Bid, revealing the connection between GTPase inactivation and mitochondrial-mediated apoptosis observed in TcsL-intoxicated cells. Levels of glycogen synthase kinase-3beta declined during later times of TcsL intoxication, suggesting a second intermediate step in apoptosis. Collectively, these data provide insight into the cascade of signaling events that lead to apoptotic death of TcsL-intoxicated cells.
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Affiliation(s)
- Daniel E Voth
- Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, 975 N.E. 10th St., BRC-362A, Oklahoma City, OK 73104, USA
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33
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Jank T, Giesemann T, Aktories K. Clostridium difficile glucosyltransferase toxin B-essential amino acids for substrate binding. J Biol Chem 2007; 282:35222-31. [PMID: 17901056 DOI: 10.1074/jbc.m703138200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Recently the crystal structure of the catalytic domain of Clostridium difficile toxin B was solved ( Reinert, D. J., Jank, T., Aktories, K., and Schulz, G. E. (2005) J. Mol. Biol. 351, 973-981 ). On the basis of this structure, we studied the functional role of several amino acids located in the catalytic center of toxin B. Besides the (286)DXD(288) motif and Trp(102), which were shown to be necessary for Mn(2+) and UDP binding, respectively, we identified by alanine scanning Asp(270), Arg(273), Tyr(284), Asn(384), and Trp(520) as being important for enzyme activity. The amino acids Arg(455), Asp(461), Lys(463), and Glu(472) and residues of helix alpha17 (e.g. Glu(449)) of toxin B are essential for enzyme-protein substrate recognition. Introduction of helix alpha17 of toxin B into Clostridium sordellii lethal toxin inhibited modification of Ras subfamily proteins but enabled glucosylation of RhoA, indicating that helix alpha17 is involved in RhoA recognition by toxin B. The data allow the design of a model of the interaction of the glucosyltransferase domain of toxin B with its protein substrate RhoA.
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Affiliation(s)
- Thomas Jank
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany
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Kitadokoro K, Kamitani S, Miyazawa M, Hanajima-Ozawa M, Fukui A, Miyake M, Horiguchi Y. Crystal structures reveal a thiol protease-like catalytic triad in the C-terminal region of Pasteurella multocida toxin. Proc Natl Acad Sci U S A 2007; 104:5139-44. [PMID: 17360394 PMCID: PMC1829276 DOI: 10.1073/pnas.0608197104] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pasteurella multocida toxin (PMT), one of the virulence factors produced by the bacteria, exerts its toxicity by up-regulating various signaling cascades downstream of the heterotrimeric GTPases Gq and G12/13 in an unknown fashion. Here, we present the crystal structure of the C-terminal region (residues 575-1,285) of PMT, which carries an intracellularly active moiety. The overall structure of C-terminal region of PMT displays a Trojan horse-like shape, composed of three domains with a "feet"-,"body"-, and "head"-type arrangement, which were designated C1, C2, and C3 from the N to the C terminus, respectively. The C1 domain, showing marked similarity in steric structure to the N-terminal domain of Clostridium difficile toxin B, was found to lead the toxin molecule to the plasma membrane. The C3 domain possesses the Cys-His-Asp catalytic triad that is organized only when the Cys is released from a disulfide bond. The steric alignment of the triad corresponded well to that of papain or other enzymes carrying Cys-His-Asp. PMT toxicities on target cells were completely abrogated when one of the amino acids constituting the triad was mutated. Our results indicate that PMT is an enzyme toxin carrying the cysteine protease-like catalytic triad dependent on the redox state and functions on the cytoplasmic face of the plasma membrane of target cells.
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Affiliation(s)
- Kengo Kitadokoro
- *Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; and
| | - Shigeki Kamitani
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
| | - Masayuki Miyazawa
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
| | - Miyuki Hanajima-Ozawa
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
| | - Aya Fukui
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
| | - Masami Miyake
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
| | - Yasuhiko Horiguchi
- Department of Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan
- To whom correspondence should be sent. E-mail:
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Jank T, Giesemann T, Aktories K. Rho-glucosylating Clostridium difficile toxins A and B: new insights into structure and function. Glycobiology 2007; 17:15R-22R. [PMID: 17237138 DOI: 10.1093/glycob/cwm004] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Clostridium difficile causes pseudomembranous colitis and is responsible for many cases of nosocomial antibiotic-associated diarrhea. Major virulence factors of C. difficile are the glucosylating exotoxins A and B. Both toxins enter target cells in a pH- dependent manner from endosomes by forming pores. They translocate the N-terminal catalytic domains into the cytosol of host cells and inactivate Rho guanosine triphosphatases by glucosylation. The crystal structure of the catalytic domain of toxin B was solved in a complex with uridine diphosphate, glucose, and manganese ion, exhibiting a folding of type A family glycosyltransferases. Crystallization of fragments of the C-terminus of toxin A, which is characterized by polypeptide repeats, revealed a solenoid-like structure often found in bacterial cell surface proteins. These studies, which provide new insights into structure, uptake, and function of the family of clostridial glucosylating toxins, are reviewed.
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Affiliation(s)
- Thomas Jank
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Otto-Krayer-Haus, Albertstrasse 25, D-79104 Freiburg, Germany
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Aldape MJ, Bryant AE, Stevens DL. Clostridium sordellii infection: epidemiology, clinical findings, and current perspectives on diagnosis and treatment. Clin Infect Dis 2006; 43:1436-46. [PMID: 17083018 DOI: 10.1086/508866] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 07/17/2006] [Indexed: 12/27/2022] Open
Abstract
Clostridium sordellii infections pose difficult clinical challenges and are usually fatal. Most commonly, these infections occur after trauma, childbirth, and routine gynecological procedures, but they have recently been associated with medically induced abortions and injection drug use. We report 2 fatal cases, one of which was associated with minor trauma, and the other of which was associated with normal childbirth, and we summarize the clinical features of 43 additional cases of reported C. sordellii infection. Of these 45 cases, 8 (18%) were associated with normal childbirth, 5 (11%) were associated with medically induced abortion, and 2 (0.4%) were associated with spontaneous abortion. The case-fatality rate was 100% in these groups. Ten (22%) of the C. sordellii infections occurred in injection drug users, and 50% of these patients died. Other cases of C. sordellii infection (in 19 patients [43%]) occurred after trauma or surgery, mostly in healthy persons, and 53% these patients died. Overall, the mortality rate was 69% (31 of 45 patients). Eighty-five percent of all patients with fatal cases died within 2-6 days of initial infection, and nearly 80% of fatal cases developed leukemoid reactions. Rapid diagnostic tests and improved treatments are needed to reduced the morbidity and mortality associated with this devastating infection.
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Affiliation(s)
- M J Aldape
- Veterans Affairs Medical Center, Boise, ID 83702, USA.
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Ugolev Y, Molshanski-Mor S, Weinbaum C, Pick E. Liposomes comprising anionic but not neutral phospholipids cause dissociation of Rac(1 or 2) x RhoGDI complexes and support amphiphile-independent NADPH oxidase activation by such complexes. J Biol Chem 2006; 281:19204-19. [PMID: 16702219 DOI: 10.1074/jbc.m600042200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Activation of the phagocyte NADPH oxidase involves the assembly of a membrane-localized cytochrome b559 with the cytosolic components p47(phox), p67(phox), p40(phox), and the GTPase Rac (1 or 2). In resting phagocytes, Rac is found in the cytosol as a prenylated protein in the GDP-bound form, associated with the Rho GDP dissociation inhibitor (RhoGDI). In the process of NADPH oxidase activation, Rac is dissociated from RhoGDI and translocates to the membrane, in concert with the other cytosolic components. The mechanism responsible for dissociation of Rac from RhoGDI is poorly understood. We generated Rac(1 or 2) x RhoGDI complexes in vitro from recombinant Rac(1 or 2), prenylated enzymatically, and recombinant RhoGDI, and purified these by anion exchange chromatography. Exposing Rac(1 or 2)(GDP) x RhoGDI complexes to liposomes containing four different anionic phospholipids caused the dissociation of Rac(1 or 2)(GDP) from RhoGDI and its binding to the anionic liposomes. Rac2(GDP) x RhoGDI complexes were more resistant to dissociation, reflecting the lesser positive charge of Rac2. Liposomes consisting of neutral phospholipid did not cause dissociation of Rac(1 or 2) x RhoGDI complexes. Rac1 exchanged to the hydrolysis-resistant GTP analogue, GMPPNP, associated with RhoGDI with lower affinity than Rac1(GDP) and Rac1(GMPPNP) x RhoGDI complexes were more readily dissociated by anionic liposomes. Rac1(GMPPNP) x RhoGDI complexes elicited NADPH oxidase activation in native phagocyte membrane liposomes in the presence of p67(phox), without the need for an anionic amphiphile, as activator. Both Rac1(GDP) x RhoGDI and Rac1(GMPPNP) x RhoGDI complexes elicited amphiphile-independent, p67(phox)-dependent NADPH oxidase activation in phagocyte membrane liposomes enriched in anionic phospholipids but not in membrane liposomes enriched in neutral phospholipids.
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Affiliation(s)
- Yelena Ugolev
- Julius Friedrich Cohnheim-Minerva Center for Phagocyte Research and the Ela Kodesz Institute of Host Defense against Infectious Diseases, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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Mesmin B, Antonny B. GEF and glucosylation assays on liposome-bound Rac. Methods Enzymol 2006; 406:70-80. [PMID: 16472650 DOI: 10.1016/s0076-6879(06)06006-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Rac binds tightly to lipid membranes through a lipid modification. The influence of the lipid membrane environment on the multiple interactions of Rac has not been well documented. In this chapter, we detail a method to prepare geranyl-geranylated Rac bound to liposomes of defined composition. With this method, one can dissect some lipid-protein interactions that facilitate the interaction of Rac with other proteins such as guanine nucleotide exchange factors and bacterial toxins.
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Affiliation(s)
- Bruno Mesmin
- CNRS-Institut de Pharmacologie, Moleculaire et Cellulaire, Valbonne, France
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Reinert DJ, Jank T, Aktories K, Schulz GE. Structural basis for the function of Clostridium difficile toxin B. J Mol Biol 2005; 351:973-81. [PMID: 16054646 DOI: 10.1016/j.jmb.2005.06.071] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 06/13/2005] [Accepted: 06/29/2005] [Indexed: 11/22/2022]
Abstract
Toxin B is a member of the family of large clostridial cytotoxins which are of great medical importance. Its catalytic fragment was crystallized in the presence of UDP-glucose and Mn2+. The structure was determined at 2.2 A resolution, showing that toxin B belongs to the glycosyltransferase type A family. However, toxin B contains as many as 309 residues in addition to the common chainfold, which most likely contribute to the target specificity. A superposition with other glycosyltransferases shows the expected positions of the acceptor oxygen atom during glucosyl transfer and indicates further that the reaction proceeds probably along a single-displacement pathway. The C1'' donor carbon atom position is defined by the bound UDP and glucose. It assigns the surface area of toxin B that forms the interface to the target protein during the modifying reaction. A docking attempt brought the known acceptor atom, Thr37 O(gamma1) of the switch I region of the RhoA:GDP target structure, near the expected position. The relative orientation of the two proteins was consistent with both being attached to a membrane. Sequence comparisons between toxin B variants revealed that the highest exchange rate occurs around the active center at the putative docking interface, presumably due to a continuous hit-and-evasion struggle between Clostridia and their eukaryotic hosts.
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Affiliation(s)
- Dirk J Reinert
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstr. 21, 79104 Freiburg im Breisgau, Germany
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