MIPs and Their Roles in the Exchange of Metalloids (Advances in Experimental Medicine and Biology) (Advances in Experimental Medicine and Biology, 679)

Sixteen years have passed since human aquaporin-1 (AQP1) was discovered as the first water channel, facilitating trans-membrane water fluxes. Subsequent years of research showed that the water channel AQP1 was only the tip of an iceberg; the iceberg itself being the ubiquitous super family of membrane intrinsic proteins (MIPs) that facilitate trans-membrane transport of water and an increasing number of small, water-soluble and uncharged compounds. Here we introduce you to the superfamily of MIPs and provide a summary about our gradually refined understanding of the phylogenetic relationship of its members. This volume is dedicated to the metalloids, a recently discovered group of substrates for a number of specific MIPs in a diverse spectrum of organisms. Particular focus is given to the essential boron, the beneficial silicon and the highly toxic arsenic. The respective MIP isoforms that facilitate the transport of these metalloids include members from several clades of the phylogenetic tree, suggesting that metalloid transport is an ancient function within this family of channel proteins. Among all the various substrates that have been shown to be transported by MIPs, metalloids take an outstanding position. While water transport seems to be a common function of many MIPs, single isoforms in plants have been identified as being crucially important for the uptake of boric acid as well as silicic acid. Here, the function seems not to be redundant, as mutations in those genes render plants deficient in boron and silicon, respectively. Title Page 3 Copyright Page 4 PREFACE 5 ABOUT THE EDITORS... 7 ABOUT THE EDITORS... 8 PARTICIPANTS 9 Table of Contents 11 Chapter 1 Aquaporins: A Family of Highly Regulated Multifunctional Channels 15 Introduction—The Discovery of Aquaporins 15 Topology of Aquaporins 17 Selectivity of Aquaporins 17 Measurement of Aquaporin Activity and Water Movement 18 Cell Swelling Assays 18 Stopped-Flow Spectrophotometry 19 Cell Pressure Probe Measurements 19 Proton NMR 20 Aquaporin Inhibition 20 Phenotype Analysis Reveals Involvement of Aquaporins in Key Physiological Processes 20 Aquaporin Regulation: Gating and Localization 21 Phosphorylation 22 pH and Divalent Cations 23 Hetero-Oligomerization 24 Modification of the Subcellular Localization 24 Conclusion 25 References 25 Chapter 2 Phylogeny of Major Intrinsic Proteins 33 Introduction 33 A Historical Account of the MIP Phylogeny 33 Plant MIPs 35 Phylogenetic Analysis of NIPs 38 Solute Transport 40 NIP-Like Bacterial MIPs and Ancestral State of ar/R Filter 40 Conclusion 41 References 41 Chapter 3 Metalloids, Soil Chemistry and the Environment 47 Introduction 47 Historical Perspective 48 Environmental Relevance 49 Environmental Toxicity of Metalloids 49 Factors Controlling Bioavailability 50 Solid: Solution Partitioning of Metalloids 50 Speciation of Metalloids in the Environment 51 Assessing Soil Bioavailability of Metalloids 54 Conclusion 55 References 56 Chapter 4 Arsenic Transport in Prokaryotes and Eukaryotic Microbes 60 Introduction 60 Metalloid Transport in Prokaryotes 60 Metalloid Transport in Eukaryotic Microbes 64 Metalloid Uptake in Yeast 64 Metalloid Efflux in Yeast 64 Metalloid Transport in Parasites 65 Conclusion 66 References 66 Chapter 5 Metalloid Transport by Aquaglyceroporins: Consequences in the Treatment of Human Diseases 70 Introduction 70 Metalloids and Cancer 72 Uptake of Metalloids via Human Aquaglyceroporins 72 Metalloids in Protozoan Parasitic Infections 73 Parasite Aquaglyceroporins Facilitate Metalloid Transport 74 Therapeutic Modulation of AQP Permeability 76 Conclusion 79 References 79 Chapter 6 Roles of Vertebrate Aquaglyceroporins in Arsenic Transport and Detoxification 84 Introduction 84 Expression of Vertebrate Aquaglyceroporins 84 Arsenic Is Both an Environmental Toxin and Human Carcinogen 86 Uptake of Organic and Inorganic Arsenic via Aquaglyceroporins 87 Molecular Mechanisms for Arsenic Translocation by Aquaglyceroporins 90 Arsenic Toxicity in Relation of Aquaglyceroporins Regulation 91 Perspectives 92 Conclusion 92 References 92 Chapter 7 Molecular Mechanisms of Boron Transport in Plants: Involvement of Arabidopsis NIP5;1 and NIP6;1 96 Physiological Function of Boron in Plants 96 Essentiality of Boron in Plants 96 Rhamnogalacturonan-II Binds Boron 97 Involvement of Rhamnogalacturonan-II in B Function 98 Roles of B Other Than Binding to RG-II 99 Physiological Analysis of B Transport 99 Passive Diffusion 99 Channel-Mediated B Transport 100 “Active” B Transport against Concentration Gradients 100 Molecular Mechanisms of B Transport 101 BOR1, a Transport Protein Responsible for Xylem Loading 101 B-Deficiency Sensitive Mutant of Arabidopsis thaliana, bor1-1 101 B Transport Properties of bor1-1 101 BOR1 is an Efflux Transporter of Boron 101 BOR1 Degradation via Endocytosis in Response to High B Supply 102 BOR1 Paralogs in A. thaliana 103 A. thaliana NIP5;1, a Channel for Boric Acid Mediates B Uptake under B Limitation 103 Complementary Roles of BOR1 and NIP5;1 in Efficient B Transport under BLimitation 104 NIP6;1, a Channel for Boric Acid Responsible for B Distribution to Leaves under B Limitation 104 Improvement of Plant Growth Property through BOR and NIP Transporters 105 Low B Tolerant Plants 105 High B Tolerant Plants Can Be Generated through Overexpression of BOR4 105 Growth Improvement by Enhanced Expression of NIP5;1 106 Conclusion 106 References 106 Chapter 8 Silicon Transporters in Higher Plants 111 Introduction 111 Silicon Transporters 112 Influx Si Transporters 112 Influx Si Transporter (OsLsi1) in Rice 112 Isolation of Rice Si Transporter (OsLsi1) 112 Expression Pattern of OsLsi1 112 Cellular and Subcellular Localization of OsLsi1 113 Characteristics of Rice Si Transporter 113 Influx Si Transporters in Barley and Maize 115 Efflux Transporter of Silicon 115 Efflux Si Transporters in Rice 115 Isolation of Rice Efflux Si Transporter (OsLsi2) 115 Expression Pattern of OsLsi2 115 Localization of Rice Si Efflux Transporter OsLsi2 115 Characteristics of Rice Si Efflux Transporter OsLsi2 115 Efflux Transporters in Barley and Maize 116 Difference in Si Uptake System between Paddy and Field Crops 116 Silicon Transporters for Xylem Unloading 118 Conclusion 118 References 120 Chapter 9 Major Intrinsic Proteins and Arsenic Transport in Plants: New Players and Their Potential Role 123 Introduction 123 The Challenge of As Speciation in Plants 125 Transport of As in Plants 126 As(V) Uptake 126 As(III) Transport Via NIPs—Gateway for Good and Bad 126 Genetic Evidence 127 Uptake and Distribution of As in Rice and the Consequences for the Food Chain 128 Rice NIP2;1 Mediates the Uptake of Methylated As Species 129 Transport of Conjugated As Species in Plants 131 What Do the Different “Omics” Tell Us About NIP-Mediated As Transmembrane Transport? 131 The Physiological Role of NIPs 132 Do MIPs Play a Physiological Role in the Translocation of Toxic Compounds Such as As(III)? 132 Regulating Bi-Directional Flux Through MIPs 133 Plant NIPs Transport Trivalent Antimony 134 Conclusion 134 References 135 Chapter 10 Major Intrinsic Proteins in Biomimetic Membranes 139 Introduction 139 Biomimetic Membranes 140 Sensor Applications 141 Separation Applications 142 MIP Biomimetic Membranes and Osmotic Processes 142 MIP Basic Properties 142 Considerations Regarding Permeability 143 Osmotic Processes 146 Polarization Effects 148 Conclusion 148 References 150 Index 155 Aquaporins : a family of highly regulated multifunctional channels / Charles Hachez and François Chaumont Phylogeny of major intrinsic proteins / Jonas Å.H. Danielson and Urban Johanson Metalloids, soil chemistry, and the environment / Enzo Lombi and Peter E. Holm Arsenic transport in prokaryotes and eukaryotic microbes / Barry P. Rosen and Markus J. Tamøs Metalloid transport by aquaglyceroporins : consequences in the treatment of human diseases / Rita Mukhopadhyay and Eric Beitz Roles of vertebrate aquaglyceroporins in arsenic transport and detoxification / Zijuan Liu Molecular mechanisms of boron transport in plants : involvement of arabidopsis NIP5;1 and NIP6;1 / Kyoko Miwa ... [et al.] Silicon transporters in higher plants / Jian Feng Ma Major intrinsic proteins and arsenic transport in plants : new players and their potential roles / Gerd P. Bienert and Thomas P. Jahn Major intrinsic proteins in biomimetic membranes / Claus Hølix Nielsen. Front Matter....Pages i-xv Aquaporins: A Family of Highly Regulated Multifunctional Channels....Pages 1-17 Phylogeny of Major Intrinsic Proteins....Pages 19-31 Metalloids, Soil Chemistry and the Environment....Pages 33-44 Arsenic Transport in Prokaryotes and Eukaryotic Microbes....Pages 47-55 Metalloid Transport by Aquaglyceroporins: Consequences in the Treatment of Human Diseases....Pages 57-69 Roles of Vertebrate Aquaglyceroporins in Arsenic Transport and Detoxification....Pages 71-81 Molecular Mechanisms of Boron Transport in Plants: Involvement of Arabidopsis NIP5;1 and NIP6;1....Pages 83-96 Silicon Transporters in Higher Plants....Pages 99-109 Major Intrinsic Proteins and Arsenic Transport in Plants: New Players and Their Potential Role....Pages 111-125 Major Intrinsic Proteins in Biomimetic Membranes....Pages 127-142 Back Matter....Pages 143-145 This book is dedicated to the metalloids, a recently discovered group of substrates for a number of specific MIPs in a diverse spectrum of organisms. Particular focus is given to the essential boron, the beneficial silicon and the highly toxic arsenic. The respective MIP isoforms that facilitate the transport of these metalloids include members from several clades of the phylogenetic tree, suggesting that metalloid transport is an ancient function within this family of channel proteins