Toxic Plant Proteins (eBook)

Editors 6
Preface 8
Contents 10
Evolution of Plant Ribosome-Inactivating Proteins 12
1 Introduction 12
2 General Overview of the Taxonomic Distribution of A and B Domains within the Viridiplantae 13
3 Overview of the Taxonomic Distribution of A and B Domains within the Magnoliophyta (Flowering Plants) 15
3.1 ``Classical´´ Type 2 RIPs (AB proteins) 15
3.2 Other Proteins with Ricin- Domains 16
4 Molecular Evolution of Type 2 RIPs 16
4.1 General Observations Concerning the Taxonomic Distribution of Type 2 RIPs and the Occurrence of Multiple Paralogs 16
4.2 Overall Phylogeny of Type 2 RIPs 17
4.3 Special Evolutionary Events: Gene Amplification and Generation of Type A and Type B Proteins from Genuine Type 2 RIPs 19
4.4 What is the Origin of Type 2 RIP Genes? 22
4.4.1 Origin of the B-hain 22
4.4.2 Origin of the A-hain 23
5 Molecular Evolution of Type 1 RIPs 23
5.1 Dicots and Monocots Other Than Poaceae 24
5.2 Poaceae Type 1 RIPs 27
5.2.1 O. sativa 27
5.2.2 Andropogoneae: Z. mays and Sorghum bicolor 28
5.2.3 Pooideae 29
5.2.4 Relationships between the RIPs from Poaceae and Other Seed Plants 29
6 What is the Relationship between Plant and Bacterial RIPs? 31
7 Chimeric RIPs Other Than Type 2 RIPs 31
7.1 JIP60 and Other Type AC Chimeric RIPs 31
7.2 Chimeric RIP with a C-erminal D Domain 34
8 Conclusions 34
References 36
RNA N-Glycosidase Activity of Ribosome-Inactivating Proteins 38
1 Introduction 38
2 Ricin as an RNA N-lycosidase 39
2.1 28S rRNA as the Target of Modification by Ricin and Other RIPs 39
2.2 RNA N-lycosidase Activity of Ricin A-hain 41
2.3 Other RIPs 42
2.4 Major Role of RNA in Protein Synthesis 42
3 Ribosomal Mechanisms Involving the Sarcin-icin Domain 43
3.1 Eukaryotic Translation Can Be Inhibited Strongly by Dysfunction of a Small Fraction of the Ribosome Population 43
3.2 Difference in the Modes of Action between a-arcin and Ricin 43
3.3 Substrate Specificity 44
3.4 Structure of the SRL 44
4 Ribosomal RNA Apurinic Site-pecific Lyase: Intrinsic Stability of the Ribosome 46
References 48
Enzymatic Activities of Ribosome-Inactivating Proteins 51
1 Introduction 51
2 Action of RIPs on Ribosomes and rRNA 52
2.1 Site of Modification by RIPs 52
2.2 Structural Requirements in Ribosomal RNA for RIP Action 53
3 Polynucleotide:Adenosine Glycosidase Activity 56
3.1 5 Cap-ndependent Activity 56
3.2 5 Cap-ependent Activity 57
4 DNA Lyase 59
5 Bifunctional Enzymes with RIP Activity in Which the Non-IP Activity Acts on Non-ucleic Acid Substrates 59
5.1 Lipase 59
5.2 Chitinase 60
5.3 Superoxide Dismutase 60
6 Conclusions 61
References 62
Type I Ribosome-Inactivating Proteins from Saponaria officinalis 65
1 Introduction 65
2 Saporin Multigene Family and Saporin Isoforms 66
3 Saporin Biochemical Features 68
3.1 Saporin Structure 68
3.2 Saporin Catalytic Activity 71
3.3 Residues Important for the Catalytic Activity 72
3.4 Interaction with the Ribosome 73
3.5 Saporin Inhibitors 74
4 Saporin Trafficking and Toxicity in Eukaryotic Cells 75
4.1 Subcellular Distribution of Saporin Isoforms in Soapwort Tissues 75
4.2 Saporin Biosynthesis and Role in Planta 76
4.3 Intoxication Pathways in Mammalian Cells 77
5 Heterologous Expression of Saporin and Saporin Fusion Toxins 80
6 Conclusions and Perspectives 82
References 82
Type 1 Ribosome-Inactivating Proteins from the Ombú Tree (Phytolacca dioica L.) 89
1 Introduction 89
2 RIPs from P. dioica L. 90
2.1 Isolation of RIPs from Seeds and Leaves of P. dioica 92
2.2 Basic Characteristics of RIPs from Seeds and Leaves of P. dioica 92
2.3 Differential Seasonal and Age Expression in Leaves 97
2.4 Cellular Localization 98
2.5 Glycosylation of P. dioica RIPs 98
3 Enzymatic and Biological Characteristics 100
3.1 Neta-lycosidase and APG Activities 100
3.2 Toxicity to Mice 101
3.3 Immunotoxin 101
3.4 Cross-eactivity 102
3.5 Activity on Double-tranded pBR322 DNA 102
4 X-ay Crystal Structure of P. dioica RIPs 106
4.1 Atomic Resolution Studies of PD-4: A Reference RIP Structure 106
4.2 An Insight into the Active Site of PD-4: Tyr72 as a Substrate Carrier Through pi- Stacking Interactions with Aden 107
4.3 PD-1 and PD-4 -Two Homologous Proteins with Distinct Functional Properties 110
5 Concluding Remarks 111
References 112
Sambucus Ribosome-Inactivating Proteins and Lectins 117
1 Ribosome-nactivating Proteins 117
2 Occurrence and Structural Diversity of Sambucus Proteins 119
3 Similarity and Processing 122
4 Structure 126
5 Enzymic Activity 128
6 Toxicity to Cells and Animals 129
7 Interaction with Cells 130
8 Phylogenetic Relationship Among the RIPs and Lectins from Sambucus 132
9 Uses of the RIPs and Lectins From Sambucus 134
References 135
Ribosome-Inactivating Proteins from Abrus pulchellus 142
1 Introduction 142
2 Pulchellin Isoforms 145
3 The Heterologous Expression of Pulchellins 146
3.1 The Pulchellin A-hain 147
3.2 The Pulchellin B-hain 147
4 Pulchellin Endocytosis in Mammalian Cells 150
5 Structure of Pulchellin 151
6 Conclusion 153
References 154
Ribosome-Inactivating Proteins in Cereals 157
1 Introduction 157
2 Classification of RIPs 158
3 Applied Research on RIPs 159
4 Properties of Cereal RIPs 160
4.1 Rice RIPs 160
4.2 Wheat RIPs 161
4.3 Barley RIPs 161
4.4 Maize RIPs 162
5 Transgenic Plants Expressing RIPs 164
6 Conclusions 169
References 170
Ribosome Inactivating Proteins and Apoptosis 175
1 Introduction 175
2 Mechanism of Action of RIPs 176
3 Apoptosis 177
4 Ribosome Inactivating Proteins and Apoptosis 179
4.1 Activation of Intrinsic Pathway of Apoptosis by General Stress 180
4.2 Activation of the Extrinsic Pathway of Apoptosis 182
4.3 Impaired Balance Between and Pro-and Anti-poptotic Factors 183
4.4 Induction of Apoptosis in Response to Ribotoxic Stress 184
4.5 The Intrinsic Nuclease Activity of Toxins 187
4.6 Alternate Pathways 187
4.6.1 PARP Activation Resulting in NAD+Depletion 187
4.6.2 Down-egulation of Telomerase 188
4.6.3 Inhibition of Histone Deacetylase 188
4.6.4 Degradation of Cytoskeleton Proteins 189
4.6.5 Nitric Oxide-ediated Apoptosis Pathway 189
5 Conclusion 189
References 189
The Synthesis of Ricinus communis Lectins 198
1 Introduction 198
2 Ricin 199
2.1 Synthesis and Quality Control of Proricin 199
2.1.1 Synthesis and ER Translocation 200
2.1.2 Anterograde Trafficking 200
2.2 Ricin A Chain: ER Synthesis and Turnover in the Cytosol 203
2.3 Ricin B Chain: Synthesis and Quality Control 206
3 RCA 1 206
3.1 RCA Synthesis and Assembly 207
4 Concluding Remarks 207
References 207
How Ricin Reaches its Target in the Cytosol of Mammalian Cells 213
1 Introduction 213
2 Cytotoxicity Model 214
3 Cell Entry 215
3.1 Cell Surface Events Remain Cryptic 215
3.2 Retrograde Trafficking 215
3.3 Ricin Is Delivered to the ER 218
3.4 Ricin Is Reduced to its Constituent Chains in the ER 219
3.5 RTA Unfolds in the ER 219
3.6 Chaperone Interactions in the ER 221
3.7 The Dislocation Process for RTA Remains Mysterious 222
4 Recovery of Activity in the Cytosol 223
5 Conclusions 225
References 226
Ribosome-Inactivating Protein-Containing Conjugates for Therapeutic Use 231
1 Introduction 231
2 Distribution 233
2.1 Enzymatic Activity 234
2.2 Toxicity 235
3 Properties of RIPs 236
3.1 Other Biological Properties 237
3.2 Possible Uses 237
3.3 Role in Nature 238
4 RIP-Based Immunotoxins 238
4.1 Chemical Immunotoxins 238
4.2 Recombinant Immunotoxins 239
4.3 In Vitro Cytotoxicity 241
4.4 Enhancement of Cytotoxicity 241
4.4.1 Lysosomotropic Amines and Carboxylic Ionophores 241
4.4.2 Ammonium Chloride (NH4Cl) 242
4.4.3 Chloroquine 242
4.4.4 Other Lysosomotropic Amines (Methylamine, Amantadine) 242
4.4.5 Carboxylic Ionophores 243
4.4.6 Antagonists of Ca++ Channels and Other Compounds3.4.6 Antagonists of Ca++ channels and other compounds 244
4.4.7 Verapamil and Its Derivatives 244
4.4.8 Perhexiline and Indolizines 245
4.4.9 Ricin B-Chain 245
4.4.10 Viruses 246
4.4.11 Saponins 246
5 Animal Studies 246
6 Ex Vivo Bone Marrow Purging with Immunotoxins 248
7 Clinical Studies 249
7.1 Hematologic Tumors 249
7.1.1 Hodgkin´s Lymphoma 250
7.1.2 Non-Hodgkin´s Lymphoma 250
7.1.3 Leukemia 251
7.1.4 Multiple Myeloma 252
7.1.5 Cutaneous Lymphoma 252
7.2 Cerebrospinal Fluid Spread of Tumors 252
7.3 Solid Tumors 252
7.3.1 Small-Cell Lung Cancer (SCLC) 252
7.3.2 Bladder Cancer 253
7.3.3 Breast Tumors 253
7.3.4 Colon Carcinoma 253
7.3.5 Melanoma 254
8 Autoimmune Diseases 254
8.1 RA 254
8.2 SLE 255
9 Other Applications 255
9.1 Corneal Opacification 255
10 Problems and Opportunities in the Future Development of Immunotoxins 255
10.1 Selection of Patients 255
10.2 Immunogenicity 256
10.3 Side Effects 257
11 Conclusions 258
References 259
Index 270