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Papatheodorou P, Minton NP, Aktories K, Barth H. An Updated View on the Cellular Uptake and Mode-of-Action of Clostridioides difficile Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1435:219-247. [PMID: 38175478 DOI: 10.1007/978-3-031-42108-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Research on the human gut pathogen Clostridioides (C.) difficile and its toxins continues to attract much attention as a consequence of the threat to human health posed by hypervirulent strains. Toxin A (TcdA) and Toxin B (TcdB) are the two major virulence determinants of C. difficile. Both are single-chain proteins with a similar multidomain architecture. Certain hypervirulent C. difficile strains also produce a third toxin, namely binary toxin CDT (C. difficile transferase). C. difficile toxins are the causative agents of C. difficile-associated diseases (CDADs), such as antibiotics-associated diarrhea and pseudomembranous colitis. For that reason, considerable efforts have been expended to unravel their molecular mode-of-action and the cellular mechanisms responsible for their uptake. Many of these studies have been conducted in European laboratories. Here, we provide an update on our previous review (Papatheodorou et al. Adv Exp Med Biol, 2018) on important advances in C. difficile toxins research.
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Affiliation(s)
- Panagiotis Papatheodorou
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany.
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre, University of Nottingham, Nottingham, UK
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Holger Barth
- Institute of Experimental and Clinical Pharmacology, Toxicology and Pharmacology of Natural Products, Ulm University Medical Center, Ulm, Germany
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Paparella A, Cahill SM, Aboulache BL, Schramm VL. Clostridioides difficile TcdB Toxin Glucosylates Rho GTPase by an S Ni Mechanism and Ion Pair Transition State. ACS Chem Biol 2022; 17:2507-2518. [PMID: 36038138 PMCID: PMC9486934 DOI: 10.1021/acschembio.2c00408] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Toxins TcdA and TcdB from Clostridioides difficile glucosylate human colon Rho GTPases. TcdA and TcdB glucosylation of RhoGTPases results in cytoskeletal changes, causing cell rounding and loss of intestinal integrity. Clostridial toxins TcdA and TcdB are proposed to catalyze glucosylation of Rho GTPases with retention of stereochemistry from UDP-glucose. We used kinetic isotope effects to analyze the mechanisms and transition-state structures of the glucohydrolase and glucosyltransferase activities of TcdB. TcdB catalyzes Rho GTPase glucosylation with retention of stereochemistry, while hydrolysis of UDP-glucose by TcdB causes inversion of stereochemistry. Kinetic analysis revealed TcdB glucosylation via the formation of a ternary complex with no intermediate, supporting an SNi mechanism with nucleophilic attack and leaving group departure occurring on the same face of the glucose ring. Kinetic isotope effects combined with quantum mechanical calculations revealed that the transition states of both glucohydrolase and glucosyltransferase activities of TcdB are highly dissociative. Specifically, the TcdB glucosyltransferase reaction proceeds via an SNi mechanism with the formation of a distinct oxocarbenium phosphate ion pair transition state where the glycosidic bond to the UDP leaving group breaks prior to attack of the threonine nucleophile from Rho GTPase.
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Abstract
Posttranslational modifications (PTMs) are important physiological means to regulate the activities and structures of central regulatory proteins in health and disease. Small GTPases have been recognized as important molecules that are targeted by PTMs during infections of mammalian cells by bacterial pathogens. The enzymes DrrA/SidM and AnkX from Legionella pneumophila AMPylate and phosphocholinate Rab1b during infection, respectively. Cdc42 is AMPylated by IbpA from Histophilus somni at tyrosine 32 or by VopS from Vibrio parahaemolyticus at threonine 35. These modifications take place in the important regulatory switch I or switch II regions of the GTPases. Since Rab1b and Cdc42 are central regulators of intracellular vesicular trafficking and of the actin cytoskeleton, their modifications by bacterial pathogens have a profound impact on the course of infection. Here, we addressed the biochemical and structural consequences of GTPase AMPylation and phosphocholination. By combining biochemical experiments and NMR analysis, we demonstrate that AMPylation can overrule the activity state of Rab1b that is commonly dictated by binding to guanosine diphosphate or guanosine triphosphate. Thus, PTMs may exert conformational control over small GTPases and may add another previously unrecognized layer of activity control to this important regulatory protein family.
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Cellular Uptake and Mode-of-Action of Clostridium difficile Toxins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1050:77-96. [DOI: 10.1007/978-3-319-72799-8_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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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: 196] [Impact Index Per Article: 28.0] [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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Metal Ion Activation of Clostridium sordellii Lethal Toxin and Clostridium difficile Toxin B. Toxins (Basel) 2016; 8:109. [PMID: 27089365 PMCID: PMC4848635 DOI: 10.3390/toxins8040109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 04/05/2016] [Accepted: 04/05/2016] [Indexed: 12/02/2022] Open
Abstract
Lethal Toxin from Clostridium sordellii (TcsL) and Toxin B from Clostridium difficile (TcdB) belong to the family of the “Large clostridial glycosylating toxins.” These toxins mono-O-glucosylate low molecular weight GTPases of the Rho and Ras families by exploiting UDP-glucose as a hexose donor. TcsL is casually involved in the toxic shock syndrome and the gas gangrene. TcdB—together with Toxin A (TcdA)—is causative for the pseudomembranous colitis (PMC). Here, we present evidence for the in vitro metal ion activation of the glucosyltransferase and the UDP-glucose hydrolysis activity of TcsL and TcdB. The following rating is found for activation by divalent metal ions: Mn2+ > Co2+ > Mg2+ >> Ca2+, Cu2+, Zn2+. TcsL and TcdB thus require divalent metal ions providing an octahedral coordination sphere. The EC50 values for TcsL were estimated at about 28 µM for Mn2+ and 180 µM for Mg2+. TcsL and TcdB further require co-stimulation by monovalent K+ (not by Na+). Finally, prebound divalent metal ions were dispensible for the cytopathic effects of TcsL and TcdB, leading to the conclusion that TcsL and TcdB recruit intracellular metal ions for activation of the glucosyltransferase activity. With regard to the intracellular metal ion concentrations, TcsL and TcdB are most likely activated by K+ and Mg2+ (rather than Mn2+) in mammalian target cells.
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Luitz MP, Bomblies R, Ramcke E, Itzen A, Zacharias M. Adenylylation of Tyr77 stabilizes Rab1b GTPase in an active state: A molecular dynamics simulation analysis. Sci Rep 2016; 6:19896. [PMID: 26818796 PMCID: PMC4730224 DOI: 10.1038/srep19896] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 12/21/2015] [Indexed: 11/09/2022] Open
Abstract
The pathogenic pathway of Legionella pneumophila exploits the intercellular vesicle transport system via the posttranslational attachment of adenosine monophosphate (AMP) to the Tyr77 sidechain of human Ras like GTPase Rab1b. The modification, termed adenylylation, is performed by the bacterial enzyme DrrA/SidM, however the effect on conformational properties of the molecular switch mechanism of Rab1b remained unresolved. In this study we find that the adenylylation of Tyr77 stabilizes the active Rab1b state by locking the switch in the active signaling conformation independent of bound GTP or GDP and that electrostatic interactions due to the additional negative charge in the switch region make significant contributions. The stacking interaction between adenine and Phe45 however, seems to have only minor influence on this stabilisation. The results may also have implications for the mechanistic understanding of conformational switching in other signaling proteins.
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Affiliation(s)
- Manuel P Luitz
- Physics Department T38, Technische Universität München, 85748 Garching, Germany
| | - Rainer Bomblies
- Physics Department T38, Technische Universität München, 85748 Garching, Germany
| | - Evelyn Ramcke
- Center for Integrated Protein Science Munich, Technische Universität München, Department Chemistry, 85748 Garching, Germany
| | - Aymelt Itzen
- Center for Integrated Protein Science Munich, Technische Universität München, Department Chemistry, 85748 Garching, Germany
| | - Martin Zacharias
- Physics Department T38, Technische Universität München, 85748 Garching, Germany
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Zeiser J, Gerhard R, Just I, Pich A. Substrate specificity of clostridial glucosylating toxins and their function on colonocytes analyzed by proteomics techniques. J Proteome Res 2013; 12:1604-18. [PMID: 23387933 DOI: 10.1021/pr300973q] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Clostridium difficile is the major cause of intestinal infections in hospitals. The major virulence factors are toxin A (TcdA) and toxin B (TcdB), which belong to the group of clostridial glucosylating toxins (CGT) that inactivate small GTPases. After a 24 h incubation period with TcdA or a glucosyltransferase-deficient mutant TcdA (gdTcdA), quantitative changes in the proteome of colonic cells (Caco-2) were analyzed using high-resolution LC-MS/MS and the SILAC technique. The changes in abundance of more than 5100 proteins were quantified. Nearly 800 toxin-responsive proteins were identified that were involved in cell cycle, cell structure, and adhesion as well as metabolic processes. Several proteins localized to mitochondria or involved in lipid metabolism were consistently of higher abundance after TcdA treatment. All changes of protein abundance depended on the glucosyltransferase activity of TcdA. Glucosylation of the known targets of TcdA such as RhoA, RhoC, RhoG was detected by LC-MS/MS. In addition, an almost complete glucosylation of Rap1(A/B), Rap2(A/B/C) and a partial glucosylation of Ral(A/B) and (H/K/N)Ras were detected. The glucosylation pattern of TcdA was compared to that of other CGT like TcdB, the variant TcdB from C. difficile strain VPI 1470 (TcdBF), and lethal toxin from C. sordellii (TcsL).
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Affiliation(s)
- Johannes Zeiser
- Hannover Medical School, Institute of Toxicology , Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Brandes V, Schelle I, Brinkmann S, Schulz F, Schwarz J, Gerhard R, Genth H. Protection from Clostridium difficile toxin B-catalysed Rac1/Cdc42 glucosylation by tauroursodeoxycholic acid-induced Rac1/Cdc42 phosphorylation. Biol Chem 2013; 393:77-84. [PMID: 22628301 DOI: 10.1515/bc-2011-198] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 11/03/2011] [Indexed: 02/02/2023]
Abstract
Toxin A (TcdA) and toxin B (TcdB) are the major virulence factors of Clostridium difficile-associated diarrhoea (CDAD). TcdA and TcdB mono-glucosylate small GTPases of the Rho family, thereby causing actin re-organisation in colonocytes, resulting in the loss of colonic barrier function. The hydrophilic bile acid tauroursodeoxycholic acid (TUDCA) is an approved drug for the treatment of cholestasis and biliary cirrhosis. In this study, TUDCA-induced activation of Akt1 is presented to increase cellular levels of pS71-Rac1/Cdc42 in human hepatocarcinoma (HepG2) cells, showing for the first time that bile acid signalling affects the activity of Rho proteins. Rac1/Cdc42 phosphorylation, in turn, protects Rac1/Cdc42 from TcdB-catalysed glucosylation and reduces the TcdB-induced cytopathic effects in HepG2 cells. The results of this study indicate that TUDCA may prove useful as a therapeutic agent for the treatment of CDAD.
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Affiliation(s)
- Vanessa Brandes
- Institut für Toxikologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
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Abstract
Many bacterial pathogens produce protein toxins to outmanoeuvre the immune system of the host. Some of these proteins target regulatory GTPases such as those belonging to the RHO family, which control the actin cytoskeleton of the host cell. In this Review, I discuss a diversity of mechanisms that are used by bacterial effectors and toxins to modulate the activity of host GTPases, with a focus on covalent modifications such as ADP-ribosylation, glucosylation, adenylylation, proteolysis, deamidation and transglutamination.
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Affiliation(s)
- Klaus Aktories
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104 Freiburg, Germany.
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Functional implications of lethal toxin-catalysed glucosylation of (H/K/N)Ras and Rac1 in Clostridium sordellii-associated disease. Eur J Cell Biol 2010; 90:959-65. [PMID: 21134703 DOI: 10.1016/j.ejcb.2010.10.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 10/19/2010] [Accepted: 10/19/2010] [Indexed: 11/20/2022] Open
Abstract
Clostridium sordellii-based diseases in humans and livestock rely on the activity of the major virulence factors, the single-chain protein toxins TcsL and TcsH, both belonging to the large clostridial glucosylating toxins. TcsL exclusively glucosylates Rho and Ras low molecular weight GTP-binding proteins. TcsL-induced loss of barrier function in epithelial (diarrhoea) and endothelial cells (extravasation of blood fluid) is based on Rac glucosylation whereas induction of apoptosis results from glucosylation of Ras. Intracellular glucosylation of Rac and Ras can be tracked by immunoblot applying the glucosylation-sensitive antibodies Rac1(Mab 102) and Ras(Mab 27H5). Induction of apoptosis especially of phagocytotic cells is crucial for the severity of C. sordellii-associated disease. The inhibition of TcsL-induced apoptosis by tauroursodeoxycholic acid (TUDCA) may be a promising therapeutic option.
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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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Belyi Y, Stahl M, Sovkova I, Kaden P, Luy B, Aktories K. Region of elongation factor 1A1 involved in substrate recognition by Legionella pneumophila glucosyltransferase Lgt1: identification of Lgt1 as a retaining glucosyltransferase. J Biol Chem 2009; 284:20167-74. [PMID: 19478083 DOI: 10.1074/jbc.m109.008441] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lgt1 is one of the glucosyltransferases produced by the Gram-negative bacterium Legionella pneumophila. This enzyme modifies eukaryotic elongation factor 1A (eEF1A) at serine 53, which leads to inhibition of protein synthesis and death of target cells. Here we studied the region of eEF1A, which is essential for substrate recognition by Lgt1. We report that the decapeptide (50)GKGSFKYAWV(59) of eEF1A is efficiently modified by Lgt1. This peptide covers the loop of the helix-loop-helix region formed by helices A* and A' of eEF1A and is part of the first turn of helix A'. Substitution of either serine 53, phenylalanine 54, tyrosine 56, or tryptophan 58 by alanine abolished or severely decreased glucosylation. Lgt1 modified the decapeptide (50)GKGSFKYAWV(59) with a higher glucosylation rate than full-length eEF1A purified from yeast, suggesting that a specific conformation of eEF1A is the preferred substrate of Lgt1. A GenBank search on the basis of the substrate decapeptide for similar peptide sequences retrieved heat shock protein 70 subfamily B suppressor 1 (Hbs1) as a target for glucosylation by Lgt1. Recombinant Hbs1 and the corresponding fragment ((303)GKASFAYAWV(312)) were gluco syl a ted by Lgt1. NMR studies with the gluco syl a ted eEF1A-derived decapeptide identified an alpha-anomeric structure of the glucose-serine 53 bond and characterize Lgt1 as a retaining glucosyltransferase.
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Affiliation(s)
- Yury Belyi
- Gamaleya Research Institute, Moscow 123098, Russia
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Giesemann T, Egerer M, Jank T, Aktories K. Processing of Clostridium difficile toxins. J Med Microbiol 2008; 57:690-696. [DOI: 10.1099/jmm.0.47742-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The pathogenicity ofClostridium difficiledepends on the large clostridial glucosylating toxins A and B (TcdA and TcdB). The proteins accomplish their own uptake by a modular structure comprising a catalytic and a binding/translocation domain. Based on a proteolytic processing step solely the catalytic domain reaches the cytosol. Within the cells, the glucosyltransferases inactivate small GTPases by mono-O-glucosylation. Here, a short overview is given regarding latest insights into the intramolecular processing, which is mediated by an intrinsic protease activity.
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Affiliation(s)
- Torsten Giesemann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
| | - Martina Egerer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
| | - Thomas Jank
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
| | - Klaus Aktories
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
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15
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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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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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Walsh CT, Garneau-Tsodikova S, Gatto GJ. Protein posttranslational modifications: the chemistry of proteome diversifications. Angew Chem Int Ed Engl 2007; 44:7342-72. [PMID: 16267872 DOI: 10.1002/anie.200501023] [Citation(s) in RCA: 1057] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The diversity of distinct covalent forms of proteins (the proteome) greatly exceeds the number of proteins predicted by DNA coding capacities owing to directed posttranslational modifications. Enzymes dedicated to such protein modifications include 500 human protein kinases, 150 protein phosphatases, and 500 proteases. The major types of protein covalent modifications, such as phosphorylation, acetylation, glycosylation, methylation, and ubiquitylation, can be classified according to the type of amino acid side chain modified, the category of the modifying enzyme, and the extent of reversibility. Chemical events such as protein splicing, green fluorescent protein maturation, and proteasome autoactivations also represent posttranslational modifications. An understanding of the scope and pattern of the many posttranslational modifications in eukaryotic cells provides insight into the function and dynamics of proteome compositions.
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Affiliation(s)
- Christopher T Walsh
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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Belyi Y, Niggeweg R, Opitz B, Vogelsgesang M, Hippenstiel S, Wilm M, Aktories K. Legionella pneumophila glucosyltransferase inhibits host elongation factor 1A. Proc Natl Acad Sci U S A 2006; 103:16953-8. [PMID: 17068130 PMCID: PMC1636560 DOI: 10.1073/pnas.0601562103] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Legionella pneumophila, the causal agent of Legionnaires' disease, is an intracellular parasite and invades and proliferates within different eukaryotic cells, including human alveolar macrophages. After several 100-fold multiplication within host cells, the pathogens are released for new invasion by induction of apoptosis or necrosis. Here we report that L. pneumophila produces a glucosyltransferase, which selectively modifies an approximately 50-kDa mammalian protein by using UDP-glucose as a cosubstrate. MS analysis identified the protein substrate as the mammalian elongation factor (EF)1A. Legionella glucosyltransferase modifies its eukaryotic protein substrate at serine-53, which is located in the GTPase domain of the EF. Glucosylation of EF1A results in inhibition of eukaryotic protein synthesis and death of target cells. Our findings show a mode of inhibition of protein synthesis by microbial pathogens and offer a perspective for understanding of the host-pathogen interaction of L. pneumophila.
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Affiliation(s)
- Yury Belyi
- Gamaleya Research Institute, Ulitsa Gamalei 18, Moscow 123098, Russia
| | - Ricarda Niggeweg
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Bastian Opitz
- Department of Internal Medicine/Infectious and Pulmonary Diseases, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; and
| | - Martin Vogelsgesang
- Institute of Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
| | - Stefan Hippenstiel
- Department of Internal Medicine/Infectious and Pulmonary Diseases, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; and
| | - Matthias Wilm
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
- To whom correspondence should be addressed. E-mail:
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Majumder S, Schmidt G, Lohia A, Aktories K. EhRho1, a RhoA-like GTPase of Entamoeba histolytica, is modified by clostridial glucosylating cytotoxins. Appl Environ Microbiol 2006; 72:7842-8. [PMID: 17056697 PMCID: PMC1694214 DOI: 10.1128/aem.01826-06] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridial glucosylating cytotoxins inactivate mammalian Rho GTPases by mono-O glucosylation of a conserved threonine residue located in the switch 1 region of the target protein. Here we report that EhRho1, a RhoA-like GTPase from the protozoan parasite Entamoeba histolytica, is glucosylated by clostridial cytotoxins. Recombinant glutathione S-transferase-EhRho1 and EhRho1 from cell lysate of Entamoeba histolytica were glucosylated by Clostridium difficile toxin B and Clostridium novyi alpha-toxin. In contrast, Clostridium difficile toxin A, which shares the same mammalian protein substrates with toxin B, did not modify EhRho1. Change of threonine 52 of EhRho1 to alanine prevented glucosylation by toxin B from Clostridium difficile and by alpha-toxin from Clostridium novyi, which suggests that the equivalent threonine residues are glucosylated in mammalian and Entamoeba Rho GTPases. Lethal toxin from Clostridium sordellii did not glucosylate EhRho1 but labeled several other substrate proteins in lysates from Entamoeba histolytica in the presence of UDP-[14C]glucose.
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Walsh CT, Garneau-Tsodikova S, Gatto GJ. Posttranslationale Proteinmodifikation: die Chemie der Proteomdiversifizierung. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200501023] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Abstract
Rho proteins are master regulators of a large array of cellular functions, including control of cell morphology, cell migration and polarity, transcriptional activation, and cell cycle progression. They are the eukaryotic targets of various bacterial protein toxins and effectors, which activate or inactivate the GTPases. Here Rho-inactivating toxins and effectors are reviewed, including the families of large clostridial cytotoxins and C3-like transferases, which inactivate Rho GTPases by glucosylation and ADP-ribosylation, respectively.
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Affiliation(s)
- K Aktories
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albertstrasse 25, 79104 Freiburg, Germany.
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Gerhard R, Tatge H, Genth H, Thum T, Borlak J, Fritz G, Just I. Clostridium difficile toxin A induces expression of the stress-induced early gene product RhoB. J Biol Chem 2004; 280:1499-505. [PMID: 15531589 DOI: 10.1074/jbc.m406014200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clostridium difficile toxin A monoglucosylates the Rho family GTPases Rho, Rac, and Cdc42. Glucosylation leads to the functional inactivation of Rho GTPases and causes disruption of the actin cytoskeleton. A cDNA microarray revealed the immediate early gene rhoB as the gene that was predominantly up-regulated in colonic CaCo-2 cells after treatment with toxin A. This toxin A effect was also detectable in epithelial cells such as HT29 and Madin-Darby canine kidney cells, as well as NIH 3T3 fibroblasts. The expression of RhoB was time-dependent and correlated with the morphological changes of cells. The up-regulation of RhoB was approximately 15-fold and was based on the de novo synthesis of the GTPase because cycloheximide completely inhibited the toxin A effect. After 8 h, a steady state was reached, with no further increase in RhoB. The p38 MAPK inhibitor SB202190 reduced the expression of RhoB, indicating a participation of the p38 MAPK in this stress response. Surprisingly, newly formed RhoB protein was only partially glucosylated by toxin A, sparing a pool of potentially active RhoB, as checked by sequential C3bot-catalyzed ADP-ribosylation. A pull-down assay in fact revealed a significant amount of active RhoB in toxin A-treated cells that was not present in control cells. We demonstrate for the first time that toxin A has not only the property to inactivate the GTPases RhoA, Rac1, and Cdc42 by glucosylation, but it also has the property to generate active RhoB that likely contributes to the overall picture of toxin treatment.
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Affiliation(s)
- Ralf Gerhard
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
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Abstract
The large clostridial cytotoxins are a family of structurally and functionally related exotoxins from Clostridium difficile (toxins A and B), C. sordellii (lethal and hemorrhagic toxin) and C. novyi (alpha-toxin). The exotoxins are major pathogenicity factors which in addition to their in vivo effects are cytotoxic to cultured cell lines causing reorganization of the cytoskeleton accompanied by morphological changes. The exotoxins are single-chain protein toxins, which are constructed of three domains: receptor-binding, translocation and catalytic domain. These domains reflect the self-mediated cell entry via receptor-mediated endocytosis, translocation into the cytoplasm, and execution of their cytotoxic activity by an inherent enzyme activity. Enzymatically, the toxins catalyze the transfer of a glucosyl moiety from UDP-glucose to the intracellular target proteins which are the Rho and Ras GTPases. The covalent attachment of the glucose moiety to a conserved threonine within the effector region of the GTPases renders the Rho-GTPases functionally inactive. Whereas the molecular mode of cytotoxic effects is fully understood, the mechanisms leading to inflammatory processes in the context of disease (e.g., antibiotic-associated pseudomembranous colitis caused by Clostridium difficile) are less clear.
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Affiliation(s)
- I Just
- Institut für Toxikologie, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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