Cell Biology of Metals and Nutrients (eBook)

Rüdiger Hell studied Biology at the Technical University of Darmstadt, Germany, and completed his PhD at the University of Cologne, Germany in 1989. From 1990 to 1992 he worked at the University of California in Berkeley as a postdoctoral researcher. After returning to Germany he completed his postdoctoral thesis at the University of Bochum in 1998 and held a position at the Leibniz Institute for Plant Genetics and Crop Plant Research in Gatersleben. During that time he developed his ongoing interest in molecular mechanisms of plant nutrition, especially sulfur metabolism and cellular redox control. In 2003 he was appointed chair at the Heidelberg Institute for Plant Sciences. He served as Dean of the Faculty of Biosciences at Heidelberg University from 2005-2007, and is currently the managing director of the university’s Plant Sciences Institute. Ralf R. Mendel studied biochemistry at the Humboldt University in Berlin, completed his PhD at the Martin-Luther-University Halle in 1979 and his postdoctoral thesis in 1985. During that time he held a position at the Institute for Plant Genetics and Crop Plant Research in Gatersleben. In 1992 he was appointed Full Professor of Botany at the (now) Institute of Plant Biology of the Braunschweig University of Technology, Germany. He has been the director of the Institute since 1993 and also served as Dean of Biosciences at Braunschweig from 1997 to 1999. His research focuses on the cell biology and biochemistry of molybdenum in plants and humans.

About the Editors 6
Preface 7
Contents 9
Contributors 11
Role of Boron in Plant Growth and its Transport Mechanisms 14
Introduction: Specialty of B 14
Physiological Significance of B 15
B Essentiality in Plants and Animals 15
B Deficiency and Toxicity Symptoms in Plants 16
RG-II-B in Cell Wall and its Requirement for Plant Growth 16
Chemical Properties of B: Possible Binding Sites of B in Cell 16
Identification of RG-II-B Complex in Plant Cell Walls 17
Synthesis of RG-II and Physiological Roles of RG-II 17
A. thaliana MUR1 for Fucose Synthesis Essential for Efficient Formation of dRG-II-B 17
NpGUT1, Glucuronyltransferase 1, for Cell Adhesion and Attachment 18
Changes in RG-II Properties in Response to B Nutrition 18
Molecular Mechanism of B Transport in Plants 19
Passive Diffusion 19
Channel-mediated B Transport for Facilitation 19
A. thaliana NIP5 1, A Channel for Boric Acid for B Uptake Under B Limitation
A. thaliana NIP6 1, for Preferential Distribution of B into Growing Shoot Tissues
Active B Transport System Under Limited Supply of B 21
A. thaliana BOR1, the First Borate Transporter Identified in the Biological Systems 21
BOR1 Degradation Via Endocytosis in Response to High B Supply 22
Active B Transport System Under Toxic Level of B 22
Cellular B Distribution Under Adequate and Toxic Level of B 22
BOR1 Homologs Involved in High B Tolerance Through B Efflux in Plants 22
Retranslocation of B 23
B Transport Mechanisms in Yeast and Mammals 23
Function of a BOR1 Homolog in S. cerevisiae 24
Function of a BOR1 Homolog in Animals 24
Conclusions and Foresights 24
References 25
Calcium: Not Just Another Ion 29
Introduction 29
Nutritional and Structural Functions of Ca2+ 30
Nutritional Functions of Ca2+ 30
Structural Functions of Ca2+ 31
The Evolution of Ca2+ as a Signaling Molecule 32
Calcium Release in Response to Signals and Stimuli 33
Calcium Responses to Abiotic, Biotic Factors and Development 33
Calcium Responses to Hormones 34
Interconnection of Ca2+ Dynamics with other Second Messengers 35
Organelles and Ca2+ 35
Calcium Signaling within the Nucleus 37
Calcium Regulation by the ER 38
Mitochondrial Calcium Dynamics 39
The Role of Chloroplasts in Cellular Calcium Homeostasis 39
Channels and Transporters shaping Ca2+ Signals 40
Influx of Ca2+ 40
Voltage Dependent Channels 41
Ligand Gated Channels 41
Vacuolar and ER Ca2+ Channels 42
Efflux of Calcium 43
Calcium-Proton Antiporter 43
Phosphorylated-type ATPases 44
Signal Response Coupling of Calcium 45
Differences in Salt and Mannitol Responses 45
Differences in Symbiotic Calcium Responses 46
Calcium Binding Proteins 47
Calmodulin 47
CDPKs 48
CBLs and CIPKs 49
Conclusions 51
References 52
Cell Biology of Copper 67
Introduction 67
Functions of Cu Proteins in Plants 68
Plastocyanin 68
Cytochrome c Oxidase 68
Cu/Zn Superoxide Dismutase 69
Ethylene Receptors 69
Phytocyanins 69
Laccase and Ascorbate Oxidase 70
Polyphenol Oxidase 70
Amine Oxidase 71
Other Roles of Cu in Plants 71
Cu Movement in and out of Root Cells 71
Cu Uptake 71
Cu Export and Intercellular Reallocation 72
Root to Shoot Cu Translocation 73
Excess Cu 73
Intracellular Cu Delivery to Cu Protein Targets 74
Chloroplast: Cu Import into the Chloroplast 74
Delivery of Cu to other Compartments 76
Mitochondria 76
Endomembrane and Secretory Pathway 76
Senescence, Reallocation, and Delivery to Reproductive Tissues 77
Regulation of Copper Homeostasis 78
Transcription Factors 78
The Cu microRNAs 80
Overview 80
References 81
Iron 87
Introduction 87
The Reduction Strategy 89
The Chelation Strategy 90
Regulation of the Reduction Strategy 92
Regulation of the Chelation Strategy 94
Fe Transport within the Plant 95
Intercellular Fe Transport 95
Citrate 95
Nicotianamine 96
Iron Transport Protein (ITP) 97
Subcellular Fe Transport 97
Vacuoles 97
Chloroplasts 98
Mitochondria 99
References 100
Dissecting Pathways Involved in Manganese Homeostasis and Stress in Higher Plant Cells 107
Introduction 107
Importance of Mn in Plants and Consequences of Mn Deficiency and Excess 108
Uptake, Distribution and Detoxification 112
Uptake into the Cell 112
Subcellular Compartmentalisation 113
The Role of CAX (Cation Exchanger) Transporters and the MTP (Metal Tolerance Protein) Family of Transporters 113
The Role of Natural Resistance Associated Macrophage Protein Transporters 115
Role of P-type ATPases 116
ECA3 116
ECA1 and LCA1P-type ATPase 118
Long-Distance Transport and Seed Loading 118
Are There Transporters Yet to be Identified? 120
Chaperones for Mn? 121
Homeostasis and Aspects of Sensing, Signalling and Regulation 121
Conclusions and Future Directions 123
References 124
Cell Biology of Molybdenum 130
Introduction 131
Molybdenum Uptake into Cells 132
The Molybdenum Cofactor 132
Molybdenum Cofactor Biosynthesis 135
Step 1: Conversion of GTP into cPMP 135
Step 2: Synthesis of Molybdopterin 136
Step 3: Adenlyation of Molybdopterin 137
Step 4: Molybdenum Insertion into Molybdopterin and Crosstalk to Copper Metabolism 137
Allocation of the Molybdenum Cofactor 138
Storage and Transfer of the Molybdenum Cofactor 138
Insertion of the Molybdenum Cofactor into Molybdenum Enyzmes 139
Micro-Compartmentalization and Cytoskeleton Binding 139
Molybdenum Enzymes 140
Xanthine Dehydrogenase 141
Aldehyde Oxidase 142
Sulfite Oxidase 143
Nitrate Reductase 143
Mitochondrial Amidoxime Reducting Component 144
Posttranslational Sulfuration of Xanthine Oxidase Family-Enzymes 145
Crosstalk between Molybdenum and Iron Metabolism 146
Conclusion 147
References 148
Cellular Biology of Nitrogen Metabolism and Signaling 155
Introduction 155
Distribution of N Forms in Plant Cells 156
N in Different Tissues 156
N Cellular Distribution 156
N Fluxes Within a Plant Cell 158
Nitrate and Nitrite Fluxes 158
Ammonium Fluxes 160
Urea Transport 161
Organic N Transport 162
N Assimilation Pathways 162
N Assimilation 163
N Remobilization 164
Regulation of N Uptake and Metabolism 164
Regulation at the mRNA Level 164
Regulation at the Protein Level 167
N- Signaling: Nitric Oxide - A Special Case 168
Sources for NO in Plants 169
Mechanisms Through Which NO Affects Targets 171
Conclusion 173
References 174
Phosphorus: Plant Strategies to Cope with its Scarcity 183
Introduction 183
Phosphorus is Needed to Sustain Life 183
The Phosphorus Paradox 184
Phosphorus is Necessary for Plant Welfare 184
Phosphorus: Its Limited Availability 184
Phosphorus in Soil 185
Phosphorus Availability: Economical and Environmental Problems 185
Pi Uptake and Transport by Plants 186
Pi Uptake and Translocation in Whole Plant 186
Pi Transporters in Plants 187
The Plant Phosphate Starvation Response 188
Biochemical Adaptations of Phosphate Starved Plants 188
Gathering and Recycling Phosphorus from Organic Pi Pool 188
Solubilizing Phosphorus from Inorganic Pi Pool 189
Increasing the Pi Uptake Ratio and Translocation 190
Physiological Changes 190
Morphological Adaptations of Phosphate-Starved Plants 191
Pi Can Modify Post-Embrionary Root Development 191
RH Formation 191
Root System Architecture 192
Interaction with Other Organisms 192
Regulation and Signaling Mechanisms of Phosphate Starvation 193
Phosphate Starvation Response, a Coordinate Mechanism 193
Is There a Plant Pho Regulon? 193
Sensing Pi Status 193
Transcriptional Factors Involved in Phosphate Starvation 195
Phosphate Homeostasis 196
Signaling Pathway of Phosphate Starvation Dependent of PHR1, PHO2, and MicroRNA399 196
The Role of Sugars in Phosphate Starvation 198
The Role of Plant Hormones in the Regulation of Phosphate Starvation Response 199
Conclusions 201
References 202
Potassium 209
Potassium is an Essential Mineral Element 209
Physiological Functions of Potassium 209
Symptoms of Potassium Deficiency 211
Acclimatory Responses to Potassium Starvation 213
The Acquisition and Cellular Distribution of Potassium 216
Potassium Acquisition by Plant Roots 216
Thermodynamic Consideration of K+ Uptake and Distribution in Root Cells 217
Cellular K+ Homeostasis 218
Potassium Transport Within the Plant 218
The Molecular Biology of K+ Transporters 221
Summary 227
References 228
Selenium Metabolism in Plants 235
Introduction 235
Metabolism of Se 238
From Selenate to Selenocysteine 238
From Selenocysteine to Other Selenocompounds 239
Genetic Engineering of Plant Se Metabolism 240
Results Obtained from Various Transgenic Approaches 240
Obtained Insight into Rate-controlling Steps and Se Detoxification Mechanisms 241
Testing the Potential of the Transgenics for Phytoremediation, and as Fortified Foods 241
New Insights into Plant Se Responses and Tolerance Mechanisms 242
Results Using the Model Nonaccumulator Species Arabidopsis thaliana 242
Results Using Se Hyperaccumulators and Related Nonhyperaccumulators 243
Ecological Aspects of Plant Se Accumulation 244
Contribution of Microbes to Se Uptake and Volatilization 244
Effects of Plant Se on Ecological Partners 246
Conclusions and Future Prospects 247
References 248
Cellular Biology of Sulfur and Its Functions in Plants 252
Sulfur is an Essential Mineral Element 252
Physiological Functions of Sulfur 252
Symptoms of Sulfur Deficiency 253
Acclimatory Responses to Sulfur Starvation 254
The Acquisition and Allocation of Sulfur Compounds 255
Sulfate Acquisition by Plant Roots 255
Whole Plant Allocation of Sulfur Compounds 258
Cellular Distribution of Sulfur-containing Compounds 260
Reductive Sulfate Assimilation 260
Subcellular Organization of Reactions 260
Signal Mechanisms and Homeostasis of Uptake and Reductive Assimilation 263
Regulation of Sulfur Amino Acids Biosynthesis 265
Regulation of Cysteine Biosynthesis 265
Catabolism, Storage and Transport of Cysteine 268
Biosynthesis of Methionine 269
Catabolism, Storage and Transport of Methionine 271
Roles of GSH in Redox Homeostasis and Detoxification 272
GSH Biosynthesis and Functions 272
GSH Degradation and Detoxification of Xenobiotics 274
References 275
Zn - A Versatile Player in Plant Cell Biology 289
Zn Chemistry and Biological Functions 289
Cellular Compartmentalization of Zn 291
Physiological Range of Zn Concentrations in Plants 293
Zn Acquisition 293
Cellular Zn Homeostasis 295
Long-distance Transport and Accumulation of Zn 297
Zn Toxicity and Tolerance 299
Cell Biology of Zn Hyperaccumulation 299
Regulation of Zn Homeostasis 300
Perspectives 301
References 302
Index 307