Topics in Current Genetics 11
Series Editor: Stefan Hohmann Manfred J. Schmitt • Raffael Schaffrath (Eds.)
Microbial Protein Toxins
With 41 Figures, 6 of Them in Color; and 3 Tables
ABC Professor Dr. Manfred J. Schmitt Angewandte Molekularbiologie (FR 8.3) Universität des Saarlandes Postfach 151150 66041 Saarbrücken Germany
Privatdozent Dr. Raffael Schaffrath MLU Halle-Wittenberg Biologicum Institut für Genetik Weinbergweg 10 06120 Halle/Saale Germany
The cover illustration depicts pseudohyphal filaments of the ascomycete Saccharomyces cerevisiae that enable this organism to forage for nutrients. Pseudohyphal filaments were induced here in a wild- type haploid MATa S1278b strain by an unknown readily diffusible factor provided by growth in con- frontation with an isogenic petite yeast strain in a sealed petri dish for two weeks and photographed at 100X magnification (provided by Xuewen Pan and Joseph Heitman).
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Diphtheria toxin, diphtheria-related fusion protein toxins, and the molecular mechanism of their action against eukaryotic cells ...... 1 Ryan Ratts and John R. Murphy...... 1 Abstract ...... 1 1 Diphtheria toxin...... 1 2 Catalytic domain delivery into the eukaryotic cytosol results in an inhibition of protein synthesis ...... 2 3 Receptor binding and substitution of the native diphtheria toxin receptor binding domain with surrogate ligands ...... 3 4 Intoxication of target cells requires the toxin to pass through a low pH endosomal compartment...... 5 5 Internalization of the toxin by receptor mediated endocytosis ...... 6 6 The early endosomal compartment ...... 6 7 The transmembrane domain and channel formation ...... 8 8 The interchain disulfide bond...... 9 9 Proposed mechanisms of diphtheria toxin C domain translocation...... 11 9.1 Unassisted spontaneous translocation of the diphtheria toxin C domain ...... 11 9.2 A cytosolic translocation factor facilitates the membrane translocation of the diphtheria toxin C domain...... 12 References...... 14
Anthrax toxin and genetic aspects regulating its expression ...... 21 Amy E. Tucker and Jimmy D. Ballard...... 21 Abstract ...... 21 1 Introduction ...... 21 2 Overview of anthrax toxin...... 22 3 pXO1, the plasmid encoding AT...... 23 4 The genes of anthrax toxin: pagA, lef,and cya...... 25 5 Environmental signals regulating AT expression...... 26 6 AtxA, a global regulator of AT expression ...... 27 7 PagR, a negative regulator of PA expression ...... 28 8 AbrB, a growth phase-dependent regulator of AT production ...... 29 9 Conclusions and outlook ...... 29 References...... 31
Shiga toxins and their mechanisms of cell entry...... 35 Kirsten Sandvig, Sébastien Wälchli, and Silje U. Lauvrak...... 35 Abstract ...... 35 1 Introduction ...... 35 2 Structure of Shiga toxins ...... 37 VI Table of contents
3 Toxin interaction with cell surface receptors ...... 39 4 Endocytosis of Shiga toxins ...... 41 5 Endosome to Golgi transport of Shiga toxins...... 42 6 Toxin transport from the trans-Golgi network to the ER ...... 43 7 Furin-induced cleavage and activation of toxins...... 43 8 Transport from ER to the cytosol...... 44 9 Shiga toxin stimulates secretion of cytokines/chemokines ...... 44 10 Toxin-induced apoptosis ...... 45 11 Protection against Shiga toxin-induced disease ...... 46 12 Therapeutic use of Shiga toxins ...... 46 13 Conclusions...... 47 Acknowledgements...... 47 References...... 47
Cholera toxin: mechanisms of entry into host cells ...... 55 David E. Saslowsky, Michael Kothe, and Wayne I. Lencer...... 55 Abstract ...... 55 1 Introduction...... 55 2 Toxin structure ...... 56 4 Retrograde transport into the Golgi and ER...... 60 4.1 Possible mechanisms of ganglioside trafficking...... 60 4.2 A direct pathway from TGN to ER...... 61 5 Mechanisms of retro-translocation across the ER membrane ...... 61 6 Conclusions...... 63 Acknowledgements...... 64 References...... 64
ExoU: A cytotoxin delivered by the type III secretion system of Pseudomonas aeruginosa ...... 69 Shira D. P. Rabin and Alan R. Hauser...... 69 Abstract ...... 69 1 Introduction...... 69 2 Discovery ...... 70 3 Activity...... 71 3.1 Cell biological activity...... 71 3.2 Enzymatic activity ...... 72 3.3 Mechanism of cytotoxicity ...... 75 4 Regulation ...... 76 5 ExoU secretion as a variable trait...... 78 6 Role in virulence ...... 81 7 Role in human disease...... 82 8 Conclusion ...... 83 References...... 83 Table of contents VII
Staphylococcal alpha-toxin...... 91 Sucharit Bhakdi, Iwan Walev, Matthias Husmann, and Angela Valeva...... 91 Abstract ...... 91 1 Occurrence and biological significance...... 91 2 Properties of native toxin...... 92 3 Mechanism of action ...... 93 3.1 Binding ...... 93 3.2 Oligomerization ...... 93 3.3 Pore formation ...... 94 4 Structure ...... 95 4.1 Structure of the heptameric pore formed in detergent solution...... 95 4.2 Structure of the membrane-bound oligomer ...... 98 4.3 Structurally related pore-forming toxins...... 98 5 Cellular resistance and repair mechanisms...... 99 6 Biological effects...... 101 6.1 Cytocidal action ...... 101 6.2 Secondary cellular reactions ...... 101 6.3 Long-range effects ...... 104 6.4 Synergism between alpha-toxin and other toxins ...... 104 7 Use of alpha-toxin in cell biology ...... 104 8 Medical relevance...... 105 Acknowledgements ...... 106 References...... 106
S. cerevisiae K28 toxin - a secreted virus toxin of the A/B family of protein toxins ...... 111 Susanne Leis, Jenny Spindler, Jochen Reiter, Frank Breinig, and Manfred J. Schmitt...... 111 Abstract ...... 111 1 Introduction ...... 111 2 dsRNA viruses cause a killer phenotype in S. cerevisiae...... 112 2.1 Viral replication cycle...... 114 3 Preprotoxin processing and toxin secretion...... 115 4 Toxin uptake and retrograde transport...... 116 4.1A single disulfide bond between and exposes the ER targeting signal of the toxin...... 119 4.2 Toxin dislocation out of the ER...... 120 5 Mode of K28 toxin action...... 122 5.1 Toxin-induced apoptotic host cell responses ...... 124 6 Toxin immunity...... 125 7 Concluding remarks ...... 126 Acknowledgements ...... 126 References...... 127 VIII Table of contents
Kluyveromyces lactis zymocin and other plasmid-encoded yeast killer toxins ...... 133 Raffael Schaffrath and Friedhelm Meinhardt ...... 133 Abstract ...... 133 1 Introduction...... 133 2 The plasmid-encoded killer systemfrom Kluyveromyces lactis ...... 134 2.1 Plasmid structures, genome organizations, and gene functions...... 134 2.2 Molecular genetic manipulation, gene shuffles, and applications .. 135 3 The K. lactis zymocin complex...... 136 3.1 Zymocin subunit composition and biogenesis...... 136 3.2 Functional assignment of individual zymocin subunits...... 137 3.3 Autoimmunity of K. lactis zymocin producers...... 137 4 The zymocin response pathway of S. cerevisiae ...... 138 4.1 Target yeast spectrum and anti-proliferative effects...... 138 4.2 Zymocin sensitivity conferring genes and zymocin resistance...... 138 4.3 Zymocin docking and early response events ...... 139 4.4 Toxin-target capacity of the RNA polymerase II Elongator complex ...... 141 4.5 Other factors linked to Elongator’s TOT function...... 142 4.6 Zymocin mode of action: a working model...... 144 5 Zymocin-related yeast killer systems...... 145 6 Conclusions...... 146 Acknowledgements...... 147 References...... 148
The Ustilago maydis killer toxins...... 157 Jeremy Bruenn...... 157 Abstract ...... 157 1 Introduction...... 157 2 KP1 toxin ...... 159 2.1 Synthesis...... 159 2.2 Structure, mechanism of action, and heterologous expression ...... 159 3 KP4 toxin...... 160 3.1 Synthesis...... 160 3.2 Structure...... 160 3.3 Mechanism of action...... 162 3.4 Heterologous expression...... 164 4 KP6 toxin ...... 165 4.1 Synthesis...... 165 4.2 Structure...... 166 4.3 Mechanism of action...... 167 4.4 Heterologous expression...... 168 5 Summary ...... 168 References...... 169 Table of contents IX
Zygocin – a monomeric protein toxin secreted by virus-infected Zygosaccharomyces bailii...... 175 Frank Weiler and Manfred J.Schmitt...... 175 Abstract ...... 175 1 Zygocin is genetically encoded by a dsRNA “killer” virus...... 175 2 Zygocin is synthesized as an inactive precursor...... 177 3 Zygocin toxicity involves disruption of cellular integrity ...... 179 4 Identification of host genes conferring zygocin resistance...... 181 5 Zygocin as novel antimycotic...... 183 Acknowledgements ...... 184 References...... 184
Acidophilic structure and killing mechanism of the Pichia farinosa killer toxin SMKT...... 189 Chise Suzuki ...... 189 Abstract ...... 189 1 Introduction ...... 189 2 Properties of a halotolerant killer yeast, Pichia farinosa ...... 190 3 SMKT with an acidophilic subunit structure...... 191 3.1 SMKT consists of two distinct subunits ...... 191 3.2 SMKT preprotoxin encoded by the chromosomal gene and the maturation process ...... 192 3.3 Lethal effect of expression of SMK1 in S. cerevisiae ...... 193 3.4 Crystal structure of SMKT...... 194 3.5 Stable state and dissociation process of SMKT...... 197 4 P-type ATPase SPF1 required for sensitivity to SMKT...... 199 4.1 SPF1 encoding a novel P-type ATPase ...... 199 4.2 Feature of type V P-type ATPases...... 199 4.3 Localization of Spf1p...... 200 4.4 Phenotypes of disruptants of SPF1 ...... 201 4.5 Comparison of intracellular roles of Spf1p and Pmr1p...... 202 5 Killing and resistant mechanism of SMKT ...... 204 5.1 SMKT interacts with the cell surface of resistant cells...... 204 5.2 Interaction of SMKT with cell membranes...... 205 6 Concluding remarks ...... 208 Acknowledgements ...... 209 References...... 209 X Table of contents
Ricin: structure, synthesis, and mode of action ...... 215 J. Michael Lord and Lynne M. Roberts...... 215 Abstract ...... 215 1 Discovery ...... 215 2 Ricin structure ...... 216 3 Function of the ricin subunits...... 217 4 Ricin biosynthesis ...... 218 5 Ricin intoxication of mammalian cells...... 221 5.1 Endocytosis to the Golgi...... 221 5.2 Golgi to ER transport...... 222 6 Membrane translocation of ricin ...... 224 7 Concluding comments...... 226 References...... 227 List of contributors
Ballard, Jimmy D. University of Oklahoma, 770 Van Vleet Oval, GLCH 516, Norman, OK 73019 [email protected]
Bhakdi, Sucharit Institute of Medical Microbiology and Hygiene, Johannes Gutenberg- University Mainz, Hochhaus am Augustusplatz, D-55101 Mainz, Germany [email protected]
Breinig, Frank Angewandte Molekularbiologie, Universität des Saarlandes, Postfach 151150, Gebäude 2, D-66041 Saarbrücken, Germany
Bruenn, Jeremy Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260, USA [email protected]
Hauser, Alan R. Department of Microbiology/Immunology and Division of Infectious Diseases, Department of Medicine, Northwestern University, 303 East Chicago Avenue, Searle 6-495, Chicago, IL 60611, USA [email protected]
Husmann, Matthias Institute of Medical Microbiology and Hygiene, Johannes Gutenberg- University Mainz, Hochhaus am Augustusplatz, D-55101 Mainz, Germany
Kothe, Michael GI Cell Biology, Children’s Hospital Boston, the Harvard Digestive Diseases Center, and the Department of Pediatrics Harvard Medical School, 300 Long- wood Ave., Boston, MA 02115, USA
Lauvrak, Silje U. Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway
Leis, Susanne Angewandte Molekularbiologie, Universität des Saarlandes, Postfach 151150, Gebäude 2, D-66041 Saarbrücken, Germany XII
Lencer, Wayne I. GI Cell Biology, Children’s Hospital Boston, the Harvard Digestive Diseases Center, and the Department of Pediatrics Harvard Medical School, 300 Long- wood Ave., Boston, MA 02115, USA [email protected]
Lord, J. Michael Department of Biological Sciences, University of Warwick, Coventry CV4 7AL UK [email protected]
Meinhardt, Friedhelm Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wil- helms-Universität Münster, Corrensstr. 3, D-48149 Münster, Germany [email protected]
Murphy, John R. Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, 02118, USA [email protected]
Rabin, Shira D. P. Department of Microbiology/Immunology, Northwestern University, 303 East Chicago Avenue, Searle 6-495, Chicago IL 60611, USA
Ratts, Ryan Section of Molecular Medicine, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, 02118, USA
Reiter, Jochen Angewandte Molekularbiologie, Universität des Saarlandes, Postfach 151150, Gebäude 2, D-66041 Saarbrücken, Germany
Roberts, Lynne M. Department of Biological Sciences, University of Warwick, Coventry CV4 7AL UK
Sandvig, Kirsten Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway [email protected]
Saslowsky, David E. GI Cell Biology, Children’s Hospital Boston, the Harvard Digestive Diseases Center, and the Department of Pediatrics Harvard Medical School, 300 Long- wood Ave., Boston, MA 02115, USA List of contributors XIII
Schaffrath, Raffael Biologicum, Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany [email protected]
Schmitt, Manfred J. Angewandte Molekularbiologie, Universität des Saarlandes, Postfach 151150, Gebäude 2, D-66041 Saarbrücken, Germany [email protected]
Spindler, Jenny Angewandte Molekularbiologie, Universität des Saarlandes, Postfach 151150, Gebäude 2, D-66041 Saarbrücken, Germany
Suzuki, Chise National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305- 8642, Japan. Present address: National Institute of Livestock and Grassland Science, 2 Ikenodai, Tsukuba, Ibaraki 305-0901, Japan [email protected]
Tucker, Amy E. University of Oklahoma, 770 Van Vleet Oval, GLCH 516, Norman, OK 73019, USA
Valeva, Angela Institute of Medical Microbiology and Hygiene, Johannes Gutenberg- University Mainz, Hochhaus am Augustusplatz, D-55101 Mainz, Germany
Walev, Iwan Institute of Medical Microbiology and Hygiene, Johannes Gutenberg- University Mainz, Hochhaus am Augustusplatz, D-55101 Mainz, Germany
Wälchli, Sébastien Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway
Weiler, Frank Gastroenterologisches Labor, Medizinische Universitätsklinik Würzburg, Josef-Schneider Strasse 2, 97080 Würzburg, Germany [email protected] Diphtheria toxin, diphtheria-related fusion protein toxins, and the molecular mechanism of their action against eukaryotic cells
Ryan Ratts and John R. Murphy
Abstract
Diphtheria toxin remains one of the most successfully studied of the bacterial pro- tein toxins. A detailed understanding of the structure function relationships of the toxin and the role of each domain in the intoxication process is well understood. This understanding has led to the development of diphtheria toxin-related fusion protein toxins which are targeted toward specific cell surface receptors. The first of these targeted toxins are now approved for human clinical use in the treatment of refractory hematologic malignancies and graft-versus-host disease. In recent years, studies on the molecular mechanism by which the diphtheria toxin catalytic domain is translocated across the early endosomal membrane has revealed that a host cell cytosolic translocation factor complex facilitates the entry process. A de- tailed understanding of this process will further stimulate the development of new approaches toward the delivery of cargo, ranging from protein to nucleic acid and/or protein nucleic acids, to the eukaryotic cell cytosol.
1 Diphtheria toxin
Diphtheria toxin was first described by (Roux and Yersin 1888) in the culture me- dium of Corynebacterium diphtheriae. Of all the bacterial A/B toxins which exert their toxicity by the translocationof their enzymatically active domains into the cytosol of eukaryotic cells, diphtheria toxin (DT) and the DT-based fusion protein toxins have been among the most extensively and successfully studied. Diphtheria toxin is naturally expressed by strains of C. diphtheriae which are lysogenic for one of a family of closely related corynebacteriophages whose genome carries the structural gene encoding the toxin, tox. Diphtheria toxin is produced in precursor form with a 25 amino acid signal peptide and is co-translationally secreted as a single polypeptide chain. Upon cleavage of the signal sequence the toxin is re- leased into the culture medium in its mature form as a 535 amino acid residue pro- tein with a molecular weight of 58 kDa (Smith 1980; Smith et al. 1980; Kaczorek et al. 1983; Greenfield et al. 1983). Early biochemical analysis of diphtheria toxin revealed that the protein is ex- quisitely sensitive to serine protease (e.g. trypsin) attack which results in ‘nicking’