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Schey KL, Gletten RB, O’Neale CVT, Wang Z, Petrova RS, Donaldson PJ. Lens Aquaporins in Health and Disease: Location is Everything! Front Physiol 2022; 13:882550. [PMID: 35514349 PMCID: PMC9062079 DOI: 10.3389/fphys.2022.882550] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 03/23/2022] [Indexed: 01/07/2023] Open
Abstract
Cataract and presbyopia are the leading cause of vision loss and impaired vision, respectively, worldwide. Changes in lens biochemistry and physiology with age are responsible for vision impairment, yet the specific molecular changes that underpin such changes are not entirely understood. In order to preserve transparency over decades of life, the lens establishes and maintains a microcirculation system (MCS) that, through spatially localized ion pumps, induces circulation of water and nutrients into (influx) and metabolites out of (outflow and efflux) the lens. Aquaporins (AQPs) are predicted to play important roles in the establishment and maintenance of local and global water flow throughout the lens. This review discusses the structure and function of lens AQPs and, importantly, their spatial localization that is likely key to proper water flow through the MCS. Moreover, age-related changes are detailed and their predicted effects on the MCS are discussed leading to an updated MCS model. Lastly, the potential therapeutic targeting of AQPs for prevention or treatment of cataract and presbyopia is discussed.
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Affiliation(s)
- Kevin L. Schey
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States,*Correspondence: Kevin L. Schey,
| | - Romell B. Gletten
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Carla V. T. O’Neale
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Zhen Wang
- Department of Biochemistry, School of Medicine, Vanderbilt University, Nashville, TN, United States
| | - Rosica S. Petrova
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J. Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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McDonald TR, Rizvi MF, Ruiter BL, Roy R, Reinders A, Ward JM. Posttranslational regulation of transporters important for symbiotic interactions. PLANT PHYSIOLOGY 2022; 188:941-954. [PMID: 34850211 PMCID: PMC8825328 DOI: 10.1093/plphys/kiab544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/27/2021] [Indexed: 05/20/2023]
Abstract
Coordinated sharing of nutritional resources is a central feature of symbiotic interactions, and, despite the importance of this topic, many questions remain concerning the identification, activity, and regulation of transporter proteins involved. Recent progress in obtaining genome and transcriptome sequences for symbiotic organisms provides a wealth of information on plant, fungal, and bacterial transporters that can be applied to these questions. In this update, we focus on legume-rhizobia and mycorrhizal symbioses and how transporters at the symbiotic interfaces can be regulated at the protein level. We point out areas where more research is needed and ways that an understanding of transporter mechanism and energetics can focus hypotheses. Protein phosphorylation is a predominant mechanism of posttranslational regulation of transporters in general and at the symbiotic interface specifically. Other mechanisms of transporter regulation, such as protein-protein interaction, including transporter multimerization, polar localization, and regulation by pH and membrane potential are also important at the symbiotic interface. Most of the transporters that function in the symbiotic interface are members of transporter families; we bring in relevant information on posttranslational regulation within transporter families to help generate hypotheses for transporter regulation at the symbiotic interface.
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Affiliation(s)
- Tami R McDonald
- Department of Biology, St Catherine University, St Paul, Minnesota, USA
| | - Madeeha F Rizvi
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Bretton L Ruiter
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
| | - Rahul Roy
- Department of Biology, St Catherine University, St Paul, Minnesota, USA
| | - Anke Reinders
- College of Continuing and Professional Studies, University of Minnesota, St. Paul, Minnesota, USA
| | - John M Ward
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, Minnesota, USA
- Author for communication:
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Shivaraj SM, Mandlik R, Bhat JA, Raturi G, Elbaum R, Alexander L, Tripathi DK, Deshmukh R, Sonah H. Outstanding Questions on the Beneficial Role of Silicon in Crop Plants. PLANT & CELL PHYSIOLOGY 2022; 63:4-18. [PMID: 34558628 DOI: 10.1093/pcp/pcab145] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
Silicon (Si) is widely accepted as a beneficial element for plants. Despite the substantial progress made in understanding Si transport mechanisms and modes of action in plants, several questions remain unanswered. In this review, we discuss such outstanding questions and issues commonly encountered by biologists studying the role of Si in plants in relation to Si bioavailability. In recent years, advances in our understanding of the role of Si-solubilizing bacteria and the efficacy of Si nanoparticles have been made. However, there are many unknown aspects associated with structural and functional features of Si transporters, Si loading into the xylem, and the role of specialized cells like silica cells and compounds preventing Si polymerization in plant tissues. In addition, despite several 1,000 reports showing the positive effects of Si in high as well as low Si-accumulating plant species, the exact roles of Si at the molecular level are yet to be understood. Some evidence suggests that Si regulates hormonal pathways and nutrient uptake, thereby explaining various observed benefits of Si uptake. However, how Si modulates hormonal pathways or improves nutrient uptake remains to be explained. Finally, we summarize the knowledge gaps that will provide a roadmap for further research on plant silicon biology, leading to an exploration of the benefits of Si uptake to enhance crop production.
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Affiliation(s)
- S M Shivaraj
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
| | - Rushil Mandlik
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
- Department of Biotechnology, Panjab University, Chandigarh, Punjab 160014, India
| | - Javaid Akhter Bhat
- National Center for Soybean Improvement, Nanjing Agricultural University, Nanjing 210095, China
| | - Gaurav Raturi
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
- Department of Biotechnology, Panjab University, Chandigarh, Punjab 160014, India
| | - Rivka Elbaum
- R H Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Lux Alexander
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Bratislava SK-84215, Slovakia
| | - Durgesh Kumar Tripathi
- Amity Institute of Organic Agriculture, Amity University, Noida, Uttar Pradesh 201313, India
| | - Rupesh Deshmukh
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
| | - Humira Sonah
- National Agri-Food Biotechnology Institute (NABI), Sector 81, SAS Nagar, Mohali, Punjab 140308, India
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Su Y, Liu Z, Sun J, Wu C, Li Y, Zhang C, Zhao L. Genome-Wide Identification of Maize Aquaporin and Functional Analysis During Seed Germination and Seedling Establishment. FRONTIERS IN PLANT SCIENCE 2022; 13:831916. [PMID: 35154233 PMCID: PMC8828918 DOI: 10.3389/fpls.2022.831916] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/07/2022] [Indexed: 05/10/2023]
Abstract
Water uptake facilitates the initiation of seed germination. It is presumed that aquaporin (AQP)-mediated water inflow contributes to seed germination, but the genetic evidence is still lacking. This study aimed at genome-wide identification of ZmAQPs and further determined the physiological functions. Following a comprehensive search, a total of 41 ZmAQPs were identified according to the latest genome database. Through bioinformatic approaches, the physicochemical characteristics, phylogenetic relationships, and structural features of ZmAQPs were analyzed. The gene expression analysis of 20 high-resolution and multi-tissues samples showed that ZmAQPs had distinct spatiotemporal and tissue-specific expression profiles during seed germination and early seedling development. We then focused on the aquaporin of maize tonoplast intrinsic protein 3 (ZmTIP3), which is specifically expressed in germinating seed. A mutant zmtip3-1 with disruption of the ZmTIP3-1 gene showed shorter shoot and root length, and decreased seedling dry weight compared with the control (W22). The result revealed that ZmTIP3-1 improved the absolute content of seed protein and promoted storage reserves mobilization, suggesting that ZmTIP3 may be a positive regulator of seed vigor. This work provides valuable clues for understanding the function and possible regulatory mechanism of ZmAQPs in seed germination and seedling growth.
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Patel J, Mishra A. Plant aquaporins alleviate drought tolerance in plants by modulating cellular biochemistry, root-architecture, and photosynthesis. PHYSIOLOGIA PLANTARUM 2021; 172:1030-1044. [PMID: 33421148 DOI: 10.1111/ppl.13324] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 12/04/2020] [Accepted: 12/21/2020] [Indexed: 05/09/2023]
Abstract
Water is a vital resource for plants to grow, thrive, and complete their life cycle. In recent years, drastic changes in the climate, especially drought frequency and severity, have increased, which reduces agricultural productivity worldwide. Aquaporins are membrane channels belonging to the major intrinsic protein superfamily, which play an essential role in cellular water and osmotic homeostasis of plants under both control and water deficit conditions. A genome-wide search reveals the vast availability of aquaporin isoforms, phylogenetic relationships, different families, conserved residues, chromosomal locations, and gene structure of aquaporins. Furthermore, aquaporins gating and subcellular trafficking are commonly controlled by phosphorylation, cytosolic pH, divalent cations, reactive oxygen species, and stoichiometry. Researchers have identified their involvement in regulating hydraulic conductance, root system architecture, modulation of abiotic stress-related genes, seed viability and germination, phloem loading, xylem water exit, photosynthetic parameters, and post-drought recovery. Remarkable effects following the change in aquaporin activity and/or gene expression have been observed on root water transport properties, nutrient acquisition, physiology, transpiration, stomatal aperture, gas exchange, and water use efficiency. The present review highlights the role of different aquaporin homologs under water-deficit stress condition in model and crop plants. Moreover, the opportunity and challenges encountered to explore aquaporins for engineering drought-tolerant crop plants are also discussed here.
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Affiliation(s)
- Jaykumar Patel
- Division of Applied Phycology and Biotechnology, CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Avinash Mishra
- Division of Applied Phycology and Biotechnology, CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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Phosphorylation of TIP3 Aquaporins during Phaseolus vulgaris Embryo Development. Cells 2019; 8:cells8111362. [PMID: 31683651 PMCID: PMC6912600 DOI: 10.3390/cells8111362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 11/19/2022] Open
Abstract
The membrane phosphoproteome in plant seed changes dynamically during embryo development. We examined the patterns of Phaseolus vulgaris (common bean) seed membrane protein phosphorylation from the mid-maturation stage until two days after germination. Serine and threonine phosphorylation declined during seed maturation while tyrosine phosphorylation remained relatively constant. We discovered that the aquaporin PvTIP3;1 is the primary seed membrane phosphoprotein, and PvTIP3;2 shows a very low level of expression. The level of phosphorylated Ser7 in PvTIP3;1 increased four-fold after seed maturation. Since phosphorylation increases water channel activity, we infer that water transport by PvTIP3;1 is highest in dry and germinating seeds, which would be optimal for seed imbibition. By the use of isoform-specific, polyclonal peptide antibodies, we found that PvTIP3;2 is expressed in a developmental pattern similar to PvTIP3;1. Unexpectedly, PvTIP3;2 is tyrosine phosphorylated following seed maturation, which may suggest a mechanism for the regulation of PvTIP3;2 following seed germination. Analysis of protein secondary structure by circular dichroism spectroscopy indicated that the amino-terminal domain of PvTIP3;1 is generally unstructured, and phosphorylation increases polyproline II (PPII) helical structure. The carboxy-terminal domain also gains PPII character, but in a pH-dependent manner. These structural changes are a first step to understand TIP3 aquaporin regulation.
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Bezerra-Neto JP, de Araújo FC, Ferreira-Neto JRC, da Silva MD, Pandolfi V, Aburjaile FF, Sakamoto T, de Oliveira Silva RL, Kido EA, Barbosa Amorim LL, Ortega JM, Benko-Iseppon AM. Plant Aquaporins: Diversity, Evolution and Biotechnological Applications. Curr Protein Pept Sci 2019; 20:368-395. [PMID: 30387391 DOI: 10.2174/1389203720666181102095910] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/24/2018] [Accepted: 10/30/2018] [Indexed: 12/20/2022]
Abstract
The plasma membrane forms a permeable barrier that separates the cytoplasm from the external environment, defining the physical and chemical limits in each cell in all organisms. The movement of molecules and ions into and out of cells is controlled by the plasma membrane as a critical process for cell stability and survival, maintaining essential differences between the composition of the extracellular fluid and the cytosol. In this process aquaporins (AQPs) figure as important actors, comprising highly conserved membrane proteins that carry water, glycerol and other hydrophilic molecules through biomembranes, including the cell wall and membranes of cytoplasmic organelles. While mammals have 15 types of AQPs described so far (displaying 18 paralogs), a single plant species can present more than 120 isoforms, providing transport of different types of solutes. Such aquaporins may be present in the whole plant or can be associated with different tissues or situations, including biotic and especially abiotic stresses, such as drought, salinity or tolerance to soils rich in heavy metals, for instance. The present review addresses several aspects of plant aquaporins, from their structure, classification, and function, to in silico methodologies for their analysis and identification in transcriptomes and genomes. Aspects of evolution and diversification of AQPs (with a focus on plants) are approached for the first time with the aid of the LCA (Last Common Ancestor) analysis. Finally, the main practical applications involving the use of AQPs are discussed, including patents and future perspectives involving this important protein family.
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Affiliation(s)
- João P Bezerra-Neto
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Flávia Czekalski de Araújo
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - José R C Ferreira-Neto
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Manassés D da Silva
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Valesca Pandolfi
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Flavia F Aburjaile
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Tetsu Sakamoto
- Universidade Federal de Minas Gerais, Department of Biochemistry and Immunology, Belo Horizonte, Brazil
| | - Roberta L de Oliveira Silva
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Ederson A Kido
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
| | - Lidiane L Barbosa Amorim
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil.,Instituto Federal de Educação, Ciência e Tecnologia do Piauí, Campus Oeiras, Avenida Projetada, s/n, 64.500-000, Oeiras, Piauí, Brazil
| | - José M Ortega
- Universidade Federal de Minas Gerais, Department of Biochemistry and Immunology, Belo Horizonte, Brazil
| | - Ana M Benko-Iseppon
- Universidade Federal de Pernambuco, Genetics Department, Center of Biosciences, Av. Prof. Moraes Rego, 1235, 50.670-423, Recife, Pernambuco, Brazil
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Zhang L, Chen L, Dong H. Plant Aquaporins in Infection by and Immunity Against Pathogens - A Critical Review. FRONTIERS IN PLANT SCIENCE 2019; 10:632. [PMID: 31191567 PMCID: PMC6546722 DOI: 10.3389/fpls.2019.00632] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/26/2019] [Indexed: 05/18/2023]
Abstract
Plant aquaporins (AQPs) of the plasma membrane intrinsic protein (PIP) family face constant risk of hijack by pathogens aiming to infect plants. PIPs can also be involved in plant immunity against infection. This review will utilize two case studies to discuss biochemical and structural mechanisms that govern the functions of PIPs in the regulation of plant infection and immunity. The first example concerns the interaction between rice Oryza sativa and the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). To infect rice, Xoo uses the type III (T3) secretion system to secrete the proteic translocator Hpa1, and Hpa1 subsequently mediates the translocation of T3 effectors secreted by this system. Once shifted from bacteria into rice cells, effectors exert virulent or avirulent effects depending on the susceptibility of the rice varieties. The translocator function of Hpa1 requires cooperation with OsPIP1;3, the rice interactor of Hpa1. This role of OsPIP1;3 is related to regulatory models of effector translocation. The regulatory models have been proposed as, translocon-dependent delivery, translocon-independent pore formation, and effector endocytosis with membrane protein/lipid trafficking. The second case study includes the interaction of Hpa1 with the H2O2 transport channel AtPIP1;4, and the associated consequence for H2O2 signal transduction of immunity pathways in Arabidopsis thaliana, a non-host of Xoo. H2O2 is generated in the apoplast upon induction by a pathogen or microbial pattern. H2O2 from this source translocates quickly into Arabidopsis cells, where it interacts with pathways of intracellular immunity to confer plant resistance against diseases. To expedite H2O2 transport, AtPIP1;4 must adopt a specific conformation in a number of ways, including channel width extension through amino acid interactions and selectivity for H2O2 through amino acid protonation and tautomeric reactions. Both topics will reference relevant studies, conducted on other organisms and AQPs, to highlight possible mechanisms of T3 effector translocation currently under debate, and highlight the structural basis of AtPIP1;4 in H2O2 transport facilitated by gating and trafficking regulation.
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Affiliation(s)
- Liyuan Zhang
- Plant Immunity Research Group, National Key Laboratory of Crop Science, Department of Plant Pathology, Shandong Agricultural University, Tai’an, China
| | - Lei Chen
- Plant Immunity Research Group, National Key Laboratory of Crop Science, Department of Plant Pathology, Shandong Agricultural University, Tai’an, China
| | - Hansong Dong
- Plant Immunity Research Group, National Key Laboratory of Crop Science, Department of Plant Pathology, Shandong Agricultural University, Tai’an, China
- Plant Immunity Laboratory, Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
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Baranowski Ł, Różańska E, Sańko-Sawczenko I, Matuszkiewicz M, Znojek E, Filipecki M, Grundler FMW, Sobczak M. Arabidopsis tonoplast intrinsic protein and vacuolar H +-adenosinetriphosphatase reflect vacuole dynamics during development of syncytia induced by the beet cyst nematode Heterodera schachtii. PROTOPLASMA 2019; 256:419-429. [PMID: 30187342 PMCID: PMC6510842 DOI: 10.1007/s00709-018-1303-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 08/24/2018] [Indexed: 05/20/2023]
Abstract
Plant parasitic cyst nematodes induce specific hypermetabolic syncytial nurse cell structures in host roots. A characteristic feature of syncytia is the lack of the central vacuole and the formation of numerous small and larger vesicles. We show that these structures are formed de novo via widening of ER cisternae during the entire development of syncytium, whereas in advanced stages of syncytium development, larger vacuoles are also formed via fusion of vesicles/tubules surrounding organelle-free pre-vacuole regions. Immunogold transmission electron microscopy of syncytia localised the vacuolar markers E subunit of vacuolar H+-adenosinetriphosphatase (V-ATPase) complex and tonoplast intrinsic protein (γ-TIP1;1) mostly in membranes surrounding syncytial vesicles, thus indicating that these structures are vacuoles and that some of them have a lytic character. To study the function of syncytial vacuoles, changes in expression of AtVHA-B1, AtVHA-B2 and AtVHA-B3 (coding for isoforms of subunit B of V-ATPase), and TIP1;1 and TIP1;2 (coding for γ-TIP proteins) genes were analysed. RT-qPCR revealed significant downregulation of AtVHA-B2, TIP1;1 and TIP1;2 at the examined stages of syncytium development compared to uninfected roots. Expression of VHA-B1 and VHA-B3 decreased at 3 dpi but reached the level of control at 7 dpi. These results were confirmed for TIP1;1 by monitoring At-γ-TIP-YFP reporter construct expression. Infection test conducted on tip1;1 mutant plants showed formation of larger syncytia and higher numbers of females in comparison to wild-type plants indicating that reduced levels or lack of TIP1;1 protein promote nematode development.
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Affiliation(s)
- Łukasz Baranowski
- Department of Botany, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland
| | - Elżbieta Różańska
- Department of Botany, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland
| | - Izabela Sańko-Sawczenko
- Department of Botany, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland
| | - Mateusz Matuszkiewicz
- Department of Plant Genetics, Breeding and Biotechnology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland
| | - Ewa Znojek
- Department of Botany, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland
| | - Marcin Filipecki
- Department of Plant Genetics, Breeding and Biotechnology, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland
| | - Florian M W Grundler
- INRES - Molecular Phytomedicine, Rheinische Friedrich-Wilhelms-University of Bonn, Karlrobert-Kreiten-Straße 13, 53115, Bonn, Germany
| | - Mirosław Sobczak
- Department of Botany, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159, 02-766, Warsaw, Poland.
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Yuan D, Li W, Hua Y, King GJ, Xu F, Shi L. Genome-Wide Identification and Characterization of the Aquaporin Gene Family and Transcriptional Responses to Boron Deficiency in Brassica napus. FRONTIERS IN PLANT SCIENCE 2017; 8:1336. [PMID: 28824672 PMCID: PMC5539139 DOI: 10.3389/fpls.2017.01336] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/17/2017] [Indexed: 05/18/2023]
Abstract
Aquaporins (AQPs) are an abundant protein family and play important roles to facilitate small neutral molecule transport across membranes. Oilseed rape (Brassica napus L.) is an important oil crop in China and elsewhere in the world, and is very sensitive to low boron (B) stress. Several AQP family genes have been reported to be involved in B transport across plasma membranes in plants. In this study, a total of 121 full-length AQPs were identified and characterized in B. napus (AC genome), and could be classified into four sub-families, including 43 PIPs (plasma membrane intrinsic proteins), 35 TIPs (tonoplast intrinsic proteins), 32 NIPs (NOD26-like intrinsic proteins), and 11 SIPs (small basic intrinsic proteins). The gene characteristics of BnaAQPs were similar to those of BraAQPs (A genome) and BolAQPs (C genome) including the composition of each sub-family, gene structure, and substrate selectivity filters. The BnaNIP was the most complex AQP sub-family, reflecting the composition of substrate selectivity filter structures which affect the permeation of solution molecules. In this study, the seedlings of both B-efficient (QY10) and B-inefficient (W10) cultivars were treated with two boron (B) levels: deficient (0.25 μM B) and sufficient (25 μM B). The transcription of AQP genes in root (R), juvenile leaf (JL), and old leaf (OL) tissues of both cultivars was investigated under B deficient and sufficient conditions. Transcription of most BnaPIPs and BnaTIPs was significantly increased compared with other BnaAQPs in all the three tissues, especially in the roots, of both B-efficient and B-inefficient cultivars under both B conditions. With B deprivation, the expression of the majority of the BnaPIPs and BnaTIPs was down-regulated in the roots. However, the BnaNIPs were up-regulated. In addition, the BnaCnn_random.PIP1;4b, BnaPIP2;4s, BnaC04.TIP4;1a, BnaAnn_random.TIP1;1b, and BnaNIP5;1s (except for BnaA07.NIP5;1c and BnaC06.NIP5;1c) exhibited obvious differences at low B between B-efficient and B-inefficient cultivars. These results will help us to understand boron homeostasis in B. napus.
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Affiliation(s)
- Dan Yuan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
- Microelement Research Center/Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural UniversityWuhan, China
| | - Wei Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
- Microelement Research Center/Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural UniversityWuhan, China
| | - Yingpeng Hua
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
- Microelement Research Center/Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural UniversityWuhan, China
| | - Graham J. King
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
- Southern Cross Plant Science, Southern Cross UniversityLismore, NSW, Australia
| | - Fangsen Xu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
- Microelement Research Center/Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural UniversityWuhan, China
| | - Lei Shi
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural UniversityWuhan, China
- Microelement Research Center/Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, Huazhong Agricultural UniversityWuhan, China
- *Correspondence: Lei Shi
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Deshmukh RK, Sonah H, Bélanger RR. Plant Aquaporins: Genome-Wide Identification, Transcriptomics, Proteomics, and Advanced Analytical Tools. FRONTIERS IN PLANT SCIENCE 2016; 7:1896. [PMID: 28066459 PMCID: PMC5167727 DOI: 10.3389/fpls.2016.01896] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/30/2016] [Indexed: 05/02/2023]
Abstract
Aquaporins (AQPs) are channel-forming integral membrane proteins that facilitate the movement of water and many other small molecules. Compared to animals, plants contain a much higher number of AQPs in their genome. Homology-based identification of AQPs in sequenced species is feasible because of the high level of conservation of protein sequences across plant species. Genome-wide characterization of AQPs has highlighted several important aspects such as distribution, genetic organization, evolution and conserved features governing solute specificity. From a functional point of view, the understanding of AQP transport system has expanded rapidly with the help of transcriptomics and proteomics data. The efficient analysis of enormous amounts of data generated through omic scale studies has been facilitated through computational advancements. Prediction of protein tertiary structures, pore architecture, cavities, phosphorylation sites, heterodimerization, and co-expression networks has become more sophisticated and accurate with increasing computational tools and pipelines. However, the effectiveness of computational approaches is based on the understanding of physiological and biochemical properties, transport kinetics, solute specificity, molecular interactions, sequence variations, phylogeny and evolution of aquaporins. For this purpose, tools like Xenopus oocyte assays, yeast expression systems, artificial proteoliposomes, and lipid membranes have been efficiently exploited to study the many facets that influence solute transport by AQPs. In the present review, we discuss genome-wide identification of AQPs in plants in relation with recent advancements in analytical tools, and their availability and technological challenges as they apply to AQPs. An exhaustive review of omics resources available for AQP research is also provided in order to optimize their efficient utilization. Finally, a detailed catalog of computational tools and analytical pipelines is offered as a resource for AQP research.
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Maurel C, Boursiac Y, Luu DT, Santoni V, Shahzad Z, Verdoucq L. Aquaporins in Plants. Physiol Rev 2015; 95:1321-58. [DOI: 10.1152/physrev.00008.2015] [Citation(s) in RCA: 486] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Aquaporins are membrane channels that facilitate the transport of water and small neutral molecules across biological membranes of most living organisms. In plants, aquaporins occur as multiple isoforms reflecting a high diversity of cellular localizations, transport selectivity, and regulation properties. Plant aquaporins are localized in the plasma membrane, endoplasmic reticulum, vacuoles, plastids and, in some species, in membrane compartments interacting with symbiotic organisms. Plant aquaporins can transport various physiological substrates in addition to water. Of particular relevance for plants is the transport of dissolved gases such as carbon dioxide and ammonia or metalloids such as boron and silicon. Structure-function studies are developed to address the molecular and cellular mechanisms of plant aquaporin gating and subcellular trafficking. Phosphorylation plays a central role in these two processes. These mechanisms allow aquaporin regulation in response to signaling intermediates such as cytosolic pH and calcium, and reactive oxygen species. Combined genetic and physiological approaches are now integrating this knowledge, showing that aquaporins play key roles in hydraulic regulation in roots and leaves, during drought but also in response to stimuli as diverse as flooding, nutrient availability, temperature, or light. A general hydraulic control of plant tissue expansion by aquaporins is emerging, and their role in key developmental processes (seed germination, emergence of lateral roots) has been established. Plants with genetically altered aquaporin functions are now tested for their ability to improve plant tolerance to stresses. In conclusion, research on aquaporins delineates ever expanding fields in plant integrative biology thereby establishing their crucial role in plants.
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Affiliation(s)
- Christophe Maurel
- Biochimie et Physiologie Moléculaire des Plantes, Unité Mixte de Recherche 5004, CNRS/INRA/Montpellier SupAgro/Université de Montpellier, Montpellier, France
| | - Yann Boursiac
- Biochimie et Physiologie Moléculaire des Plantes, Unité Mixte de Recherche 5004, CNRS/INRA/Montpellier SupAgro/Université de Montpellier, Montpellier, France
| | - Doan-Trung Luu
- Biochimie et Physiologie Moléculaire des Plantes, Unité Mixte de Recherche 5004, CNRS/INRA/Montpellier SupAgro/Université de Montpellier, Montpellier, France
| | - Véronique Santoni
- Biochimie et Physiologie Moléculaire des Plantes, Unité Mixte de Recherche 5004, CNRS/INRA/Montpellier SupAgro/Université de Montpellier, Montpellier, France
| | - Zaigham Shahzad
- Biochimie et Physiologie Moléculaire des Plantes, Unité Mixte de Recherche 5004, CNRS/INRA/Montpellier SupAgro/Université de Montpellier, Montpellier, France
| | - Lionel Verdoucq
- Biochimie et Physiologie Moléculaire des Plantes, Unité Mixte de Recherche 5004, CNRS/INRA/Montpellier SupAgro/Université de Montpellier, Montpellier, France
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Ayadi M, Cavez D, Miled N, Chaumont F, Masmoudi K. Identification and characterization of two plasma membrane aquaporins in durum wheat (Triticum turgidum L. subsp. durum) and their role in abiotic stress tolerance. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:1029-39. [PMID: 21723739 DOI: 10.1016/j.plaphy.2011.06.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 06/02/2011] [Indexed: 05/21/2023]
Abstract
Plant plasma membrane intrinsic proteins (PIP) cluster in two phylogenetic groups, PIP1 and PIP2 that have different water channel activities when expressed in Xenopus oocytes. PIP2s induce a marked increase of the membrane osmotic water-permeability coefficient (P(f)), whereas PIP1s are generally inactive. Here we report the cloning of two durum wheat (Triticum turgidum L. subsp. durum) cDNAs encoding TdPIP1;1 and TdPIP2;1 belonging to the PIP1 and PIP2 subfamilies, respectively. Contrary to TdPIP1;1, expression of TdPIP2;1 in Xenopus oocytes resulted in an increase in P(f) compared to water-injected oocytes. Co-expression of the non-functional TdPIP1;1 and the functional TdPIP2;1 lead to a significant increase in P(f) compared with oocytes expressing TdPIP2;1 alone. A truncated form of TdPIP2;1, tdpip2;1, missing the first two transmembrane domains, had no water channel activity. Nonetheless, its co-expression with the functional TdPIP2;1 partially inhibits the P(f) and disrupt the activities of plant aquaporins. In contrast to the approach developed in Xenopus oocytes, phenotypic analyses of transgenic tobacco plants expressing TdPIP1;1 or TdPIP2;1 generated a tolerance phenotype towards osmotic and salinity stress. TdPIP1;1 and TdPIP2;1 are differentially regulated in roots and leaves in the salt-tolerant wheat variety when challenged with salt stress and abscisic acid. Confocal microscopy analysis of tobacco roots expressing TdPIP1;1 and TdPIP2;1 fused to the green fluorescent protein showed that the proteins were localized at the plasma membrane.
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Affiliation(s)
- Malika Ayadi
- Plant Protection and Improvement Laboratory, Centre of Biotechnology of Sfax, University of Sfax, Route Sidi Mansour Km 6, BP 1177, 3018 Sfax, Tunisia
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Hachez C, Chaumont F. Aquaporins: a family of highly regulated multifunctional channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 679:1-17. [PMID: 20666220 DOI: 10.1007/978-1-4419-6315-4_1] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Aquaporins (AQPs) were discovered as channels facilitatingwater movement across cellular membranes. Whereas much of the research has focused on characterizing AQPs with respect to cell water homeostasis, recent discoveries in terms of the transport selectivity of AQP homologs has shed new light on their physiological roles. In fact, whereas some AQPs behave as "strict" water channels, others can conduct a wide range ofnonpolar solutes, such as urea or glycerol and even more unconventional permeants, such as the nonpolar gases carbon dioxide and nitric oxide, the polar gas ammonia, the reactive oxygen species hydrogen peroxide and the metalloids antimonite, arsenite, boron and silicon. This suggests that AQPs are also key players in various physiological processes not related to water homeostasis. The function, regulation and biological importance of AQPs in the different kingdoms is reviewed in this chapter, with special emphasis on animal and plant AQPs.
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Affiliation(s)
- Charles Hachez
- Institut des Sciences de la Vie, Universit4 catholique de Louvain, Croix du Sud 5-15, B-1348 Louvain-la-Neuve, Belgium
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Schenk AD, Hite RK, Engel A, Fujiyoshi Y, Walz T. Electron crystallography and aquaporins. Methods Enzymol 2010; 483:91-119. [PMID: 20888471 DOI: 10.1016/s0076-6879(10)83005-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Electron crystallography of two-dimensional (2D) crystals can provide information on the structure of membrane proteins at near-atomic resolution. Originally developed and used to determine the structure of bacteriorhodopsin (bR), electron crystallography has recently been applied to elucidate the structure of aquaporins (AQPs), a family of membrane proteins that form pores mostly for water but also other solutes. While electron crystallography has made major contributions to our understanding of the structure and function of AQPs, structural studies on AQPs, in turn, have fostered a number of technical developments in electron crystallography. In this contribution, we summarize the insights electron crystallography has provided into the biology of AQPs, and describe technical advancements in electron crystallography that were driven by structural studies on AQP 2D crystals. In addition, we discuss some of the lessons that were learned from electron crystallographic work on AQPs.
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Affiliation(s)
- Andreas D Schenk
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts, USA
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Wudick MM, Luu DT, Maurel C. A look inside: localization patterns and functions of intracellular plant aquaporins. THE NEW PHYTOLOGIST 2009; 184:289-302. [PMID: 19674338 DOI: 10.1111/j.1469-8137.2009.02985.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Aquaporins form a superfamily of intrinsic channel proteins in the plasma and intracellular membranes of plant cells. While a lot of research effort has substantiated the importance of plasma membrane aquaporins for the regulation of plant water homeostasis, comparably little is known about the function of intracellular aquaporins. Yet, various low-molecular-weight compounds, in addition to water, were recently shown to permeate some of these aquaporins. In this review, we examine the diversity of transport properties and localization patterns of intracellular aquaporins. The discussed profiles include, for example, water and ammonia transport across the tonoplast or CO2 transport through the chloroplast envelope. Furthermore, we try to assess to what extent the diverse aquaporin distribution patterns, in relation to the high degree of compartmentation of plant cells, can be linked to a wide range of cellular functions.
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Affiliation(s)
- Michael M Wudick
- Biochimie et physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 2, France
| | - Doan-Trung Luu
- Biochimie et physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 2, France
| | - Christophe Maurel
- Biochimie et physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 2, France
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18
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Shao HB, Chu LY, Shao HB, Chu LY, Shao MA, Zhao CX. Advances in functional regulation mechanisms of plant aquaporins: Their diversity, gene expression, localization, structure and roles in plant soil-water relations (Review). Mol Membr Biol 2009; 25:179-91. [DOI: 10.1080/09687680801914508] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Beebo A, Thomas D, Der C, Sanchez L, Leborgne-Castel N, Marty F, Schoefs B, Bouhidel K. Life with and without AtTIP1;1, an Arabidopsis aquaporin preferentially localized in the apposing tonoplasts of adjacent vacuoles. PLANT MOLECULAR BIOLOGY 2009; 70:193-209. [PMID: 19229639 DOI: 10.1007/s11103-009-9465-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Accepted: 01/30/2009] [Indexed: 05/27/2023]
Abstract
The Arabidopsis thaliana Tonoplast Intrinsic Protein 1;1 (AtTIP1;1) is a member of the tonoplast aquaporin family. The tissue-specific expression pattern and intracellular localization of AtTIP1;1 were characterized using GUS and GFP fusion genes. Results indicate that AtTIP1;1 is expressed in almost all cell types with the notable exception of meristematic cells. The highest level of AtTIP1;1 expression was detected in vessel-flanking cells in vascular bundles. AtTIP1;1-GFP fusion protein labelled the tonoplast of the central vacuole and other smaller peripheral vacuoles. The fusion protein was not found evenly distributed along the tonoplast continuum but concentrated in contact zones of tonoplasts from adjacent vacuoles and in invaginations of the central vacuole. Such invaginations may result from partially engulfed small vacuoles. A knockout mutant was isolated and characterized to gain insight into AtTIP1;1 function. No phenotypic alteration was found under optimal growth conditions indicating that AtTIP1;1 function is not essential to the plant and that some members of the TIP family may act redundantly to facilitate water flow across the tonoplast. However, a conditional root phenotype was observed when mutant plants were grown on a glycerol-containing medium.
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Affiliation(s)
- Azeez Beebo
- UMR INRA 1088/CNRS 5184/Université de Bourgogne, Plante-Microbe-Environnement, BP 86510, 21065, Dijon, France.
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20
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Zhao CX, Shao HB, Chu LY. Aquaporin structure–function relationships: Water flow through plant living cells. Colloids Surf B Biointerfaces 2008; 62:163-72. [DOI: 10.1016/j.colsurfb.2007.10.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Revised: 10/08/2007] [Accepted: 10/28/2007] [Indexed: 11/25/2022]
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Katsuhara M, Hanba YT, Shiratake K, Maeshima M. Expanding roles of plant aquaporins in plasma membranes and cell organelles. FUNCTIONAL PLANT BIOLOGY : FPB 2008; 35:1-14. [PMID: 32688752 DOI: 10.1071/fp07130] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 12/04/2007] [Indexed: 06/11/2023]
Abstract
Aquaporins facilitate water transport across biomembranes in a manner dependent on osmotic pressure and water-potential gradient. The discovery of aquaporins has facilitated research on intracellular and whole-plant water transport at the molecular level. Aquaporins belong to a ubiquitous family of membrane intrinsic proteins (MIP). Plants have four subfamilies: plasma-membrane intrinsic protein (PIP), tonoplast intrinsic protein (TIP), nodulin 26-like intrinsic protein (NIP), and small basic intrinsic protein (SIP). Recent research has revealed a diversity of plant aquaporins, especially their physiological functions and intracellular localisation. A few PIP members have been reported to be involved in carbon dioxide permeability of cells. Newly identified transport substrates for NIP members of rice and Arabidopsis thaliana have been demonstrated to transport silicon and boron, respectively. Ammonia, glycerol, and hydrogen peroxide have been identified as substrates for plant aquaporins. The intracellular localisation of plant aquaporins is diverse; for example, SIP members are localised on the ER membrane. There has been much progress in the research on the functional regulation of water channel activity of PIP members including phosphorylation, formation of hetero-oligomer, and protonation of histidine residues under acidic condition. This review provides a broad overview of the range of potential aquaporins, which are now believed to participate in the transport of several small molecules in various membrane systems in model plants, crops, flowers and fruits.
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Affiliation(s)
- Maki Katsuhara
- Research Institute for Bioresources, Okayama University, Kurashiki 710-0046, Japan
| | - Yuko T Hanba
- Centre for Bioresource Field Science, Kyoto Institute of Technology, Kyoto 616-8354, Japan
| | - Katsuhiro Shiratake
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Masayoshi Maeshima
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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22
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Maurel C, Verdoucq L, Luu DT, Santoni V. Plant aquaporins: membrane channels with multiple integrated functions. ANNUAL REVIEW OF PLANT BIOLOGY 2008; 59:595-624. [PMID: 18444909 DOI: 10.1146/annurev.arplant.59.032607.092734] [Citation(s) in RCA: 696] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Aquaporins are channel proteins present in the plasma and intracellular membranes of plant cells, where they facilitate the transport of water and/or small neutral solutes (urea, boric acid, silicic acid) or gases (ammonia, carbon dioxide). Recent progress was made in understanding the molecular bases of aquaporin transport selectivity and gating. The present review examines how a wide range of selectivity profiles and regulation properties allows aquaporins to be integrated in numerous functions, throughout plant development, and during adaptations to variable living conditions. Although they play a central role in water relations of roots, leaves, seeds, and flowers, aquaporins have also been linked to plant mineral nutrition and carbon and nitrogen fixation.
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Affiliation(s)
- Christophe Maurel
- Biochimie et Physiologie Moléculaire des Plantes, SupAgro/INRA/CNRS/UM2 UMR 5004, F-34060 Montpellier Cedex 1, France.
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23
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Maurel C. Plant aquaporins: novel functions and regulation properties. FEBS Lett 2007; 581:2227-36. [PMID: 17382935 DOI: 10.1016/j.febslet.2007.03.021] [Citation(s) in RCA: 268] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 03/07/2007] [Accepted: 03/09/2007] [Indexed: 01/04/2023]
Abstract
Aquaporins are water channel proteins of intracellular and plasma membranes that play a crucial role in plant water relations. The present review focuses on the most recent findings concerning the molecular and cellular properties of plant aquaporins. The mechanisms of transport selectivity and gating (i.e. pore opening and closing) have recently been described, based on aquaporin structures at atomic resolution. Novel dynamic aspects of aquaporin subcellular localisation have been uncovered. Also, some aquaporin isoforms can transport, besides water, physiologically important molecules such as CO(2), H(2)O(2), boron or silicon. Thus, aquaporins are involved in many great functions of plants, including nutrient acquisition, carbon fixation, cell signalling and stress responses.
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Affiliation(s)
- Christophe Maurel
- Biochimie et Physiologie Moléculaire des Plantes, Agro-M/CNRS/INRA/UM2 UMR 5004, Place Viala, F-34060 Montpellier Cedex 1, France.
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Hachez C, Zelazny E, Chaumont F. Modulating the expression of aquaporin genes in planta: A key to understand their physiological functions? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1142-56. [PMID: 16580626 DOI: 10.1016/j.bbamem.2006.02.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 02/02/2006] [Accepted: 02/14/2006] [Indexed: 12/01/2022]
Abstract
Aquaporins (AQPs) are believed to act as "cellular plumbers", allowing plants to rapidly alter their membrane water permeability in response to environmental cues. This study of AQP regulation at both the RNA and protein levels has revealed a large number of possible mechanisms. Currently, modulation of AQP expression in planta is considered the strategy of choice for elucidating the role of AQPs in plant physiology. This review highlights the fact that this strategy is complicated by many factors, such as the incomplete characterization of transport selectivity of the targeted AQP, the fact that AQPs might act as multifunctional channels with multiple physiological roles, and the number of post-translational regulation mechanisms. The classification of AQPs as constitutive or stress-responsive isoforms is also proposed.
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Affiliation(s)
- Charles Hachez
- Unité de Biochimie physiologique, Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 5-15, B-1348 Louvain-la-Neuve, Belgium
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25
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Törnroth-Horsefield S, Wang Y, Hedfalk K, Johanson U, Karlsson M, Tajkhorshid E, Neutze R, Kjellbom P. Structural mechanism of plant aquaporin gating. Nature 2005; 439:688-94. [PMID: 16340961 DOI: 10.1038/nature04316] [Citation(s) in RCA: 564] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 10/14/2005] [Indexed: 11/10/2022]
Abstract
Plants counteract fluctuations in water supply by regulating all aquaporins in the cell plasma membrane. Channel closure results either from the dephosphorylation of two conserved serine residues under conditions of drought stress, or from the protonation of a conserved histidine residue following a drop in cytoplasmic pH due to anoxia during flooding. Here we report the X-ray structure of the spinach plasma membrane aquaporin SoPIP2;1 in its closed conformation at 2.1 A resolution and in its open conformation at 3.9 A resolution, and molecular dynamics simulations of the initial events governing gating. In the closed conformation loop D caps the channel from the cytoplasm and thereby occludes the pore. In the open conformation loop D is displaced up to 16 A and this movement opens a hydrophobic gate blocking the channel entrance from the cytoplasm. These results reveal a molecular gating mechanism which appears conserved throughout all plant plasma membrane aquaporins.
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Affiliation(s)
- Susanna Törnroth-Horsefield
- Department of Chemistry and Bioscience, Chalmers University of Technology, P O Box 462, SE-40530 Göteborg, Sweden
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26
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Abstract
Accumulating evidence indicates that aquaporins play a key role in plant water relations. Plant aquaporins are part of a large and highly divergent protein family that can be divided into four subfamilies according to amino acid sequence similarity. As in other organisms, plant aquaporins facilitate the transcellular movement of water, but, in some cases, also the flux of small neutral solutes across a cellular membrane. Plant cell membranes are characterized by a large range of osmotic water permeabilities, and recent data indicate that plant aquaporin activity might be regulated by gating mechanisms. The factors affecting the gating behaviour possibly involve phosphorylation, heteromerization, pH, Ca2+, pressure, solute gradients and temperature. Regulation of aquaporin trafficking may also represent a way to modulate membrane water permeability. The aim of this review is to integrate recent molecular and biophysical data on the mechanisms regulating aquaporin activity in plant membranes and to relate them to putative changes in protein structure.
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Affiliation(s)
- François Chaumont
- Unité de Biochimie Physiologique, Institut des Science de la Vie, Université catholique de Louvain, Croix du Sud 2-20, B-1348 Louvain-la-Neuve, Belgium.
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27
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Daniels MJ, Yeager M. Phosphorylation of Aquaporin PvTIP3;1 Defined by Mass Spectrometry and Molecular Modeling†. Biochemistry 2005; 44:14443-54. [PMID: 16262244 DOI: 10.1021/bi050565d] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The water channel protein PvTIP3;1 (alpha-TIP) is a member of the Major Intrinsic Protein membrane channel family. The in vitro activity of this aquaporin is dependent on phosphorylation, and the protein is phosphorylated in vivo by a membrane-associated Ca(2+)-dependent kinase. Mutagenesis studies have implicated three serine residues as kinase targets, but only phosphorylation of Ser7 has been observed in vivo. An atomic model of PvTIP3;1 generated by homology modeling suggested that Ser7 is the only residue that would be sterically accessible to kinases. To further explain the phosphorylation of PvTIP3;1, we overexpressed this aquaporin in the methylotrophic yeast Pichia pastoris and purified the hexahistidine-tagged protein by immobilized metal affinity chromatography. Mass spectrometry confirmed that a fraction of recombinant PvTIP3;1 was phosphorylated. Phosphatase and kinase treatments indicated that Ser7 was the only residue that could be phosphorylated. In addition, mass spectrometry indicated that the native and expressed proteins are N-terminally acetylated. This is the first demonstration that a full-length, recombinant aquaporin can be produced in yeast and authentically phosphorylated in vitro. Characterization of phosphorylation-mediated gating in PvTIP3;1 will serve as a paradigm for understanding gating mechanisms of other channels.
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Affiliation(s)
- Mark J Daniels
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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28
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Kukulski W, Schenk AD, Johanson U, Braun T, de Groot BL, Fotiadis D, Kjellbom P, Engel A. The 5A structure of heterologously expressed plant aquaporin SoPIP2;1. J Mol Biol 2005; 350:611-6. [PMID: 15964017 DOI: 10.1016/j.jmb.2005.05.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Revised: 04/25/2005] [Accepted: 05/02/2005] [Indexed: 11/29/2022]
Abstract
SoPIP2;1 is one of the major integral proteins in spinach leaf plasma membranes. In the Xenopus oocyte expression system its water channel activity is regulated by phosphorylation at the C terminus and in the first cytosolic loop. To assess its structure, SoPIP2;1 was heterologously expressed in Pichia pastoris as a His-tagged protein and in the non-tagged form. Both forms were reconstituted into 2D crystals in the presence of lipids. Tubular crystals and double-layered crystalline sheets of non-tagged SoPIP2;1 were observed and analyzed by cryo-electron microscopy. Crystalline sheets were highly ordered and diffracted electrons to a resolution of 2.96A. High-resolution projection maps of tilted specimens provided a 3D structure at 5A resolution. Superposition of the SoPIP2;1 potential map with the atomic model of AQP1 demonstrates the generally well conserved overall structure of water channels. Differences concerning the extracellular loop A explain the particular crystal contacts between oppositely oriented membrane sheets of SoPIP2;1 2D crystals, and may have a function in rapid volume changes observed in stomatal guard cells or mesophyll protoplasts. This crystal packing arrangement provides access to the phosphorylated C terminus as well as the loop B phosphorylation site for studies of channel gating.
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Affiliation(s)
- W Kukulski
- Maurice E. Müller Institute for Microscopy, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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29
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Wallace IS, Roberts DM. Homology modeling of representative subfamilies of Arabidopsis major intrinsic proteins. Classification based on the aromatic/arginine selectivity filter. PLANT PHYSIOLOGY 2004; 135:1059-68. [PMID: 15181215 PMCID: PMC514140 DOI: 10.1104/pp.103.033415] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2003] [Revised: 11/24/2003] [Accepted: 12/02/2003] [Indexed: 05/18/2023]
Abstract
Major intrinsic proteins (MIPs) are a family of membrane channels that facilitate the bidirectional transport of water and small uncharged solutes such as glycerol. The 35 full-length members of the MIP family in Arabidopsis are segregated into four structurally homologous subfamilies: plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin 26-like intrinsic membrane proteins (NIPs), and small basic intrinsic proteins (SIPs). Computational methods were used to construct structural models of the putative pore regions of various plant MIPs based on homology modeling with the atomic resolution crystal structures of mammalian aquaporin 1 and the bacterial glycerol permease GlpF. Based on comparisons of the narrow selectivity filter regions (the aromatic/Arg [ar/R] filter), the members of the four phylogenetic subfamilies of Arabidopsis MIPs can be classified into eight groups. PIPs possess a uniform ar/R signature characteristic of high water transport aquaporins, whereas TIPs are highly diverse with three separate conserved ar/R regions. NIPs possess two separate conserved ar/R regions, one that is similar to the archetype, soybean (Glycine max) nodulin 26, and another that is characteristic of Arabidopsis NIP6;1. The SIP subfamily possesses two ar/R subgroups, characteristic of either SIP1 or SIP2. Both SIP ar/R residues are divergent from all other MIPs in plants and other kingdoms. Overall, these findings suggest that higher plant MIPs have a common fold but show distinct differences in proposed pore apertures, potential to form hydrogen bonds with transported molecules, and amphiphilicity that likely results in divergent transport selectivities.
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Affiliation(s)
- Ian S Wallace
- Department of Biochemistry, Cellular, and Molecular Biology and Center of Excellence in Structural Biology, The University of Tennessee, Knoxville, Tennessee 37996, USA
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Lopez F, Bousser A, Sissoëff I, Gaspar M, Lachaise B, Hoarau J, Mahé A. Diurnal Regulation of Water Transport and Aquaporin Gene Expression in Maize Roots: Contribution of PIP2 Proteins. ACTA ACUST UNITED AC 2003; 44:1384-95. [PMID: 14701934 DOI: 10.1093/pcp/pcg168] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
In maize (Zea mays) roots, xylem water transfer supported by root pressure occurs during the day and is less important at night. Diurnal modifications of osmotic pressure gradient between medium and xylem could not explain the oscillation of water flux in young maize roots during the day-night cycle. We observed a high turgor pressure of root cortical cells associated with a high flux. In maize roots, ZmPIP transcripts oscillate during the day-night cycle exhibiting some characteristics of genes regulated by a circadian mechanism. The PIP protein level profile is different from the mRNA pattern. Moreover, ZmPIP1 and ZmPIP2 protein levels are differentially regulated during the light and dark period and in response to continuous darkness suggesting different roles for both classes of PIP. Finally, our results suggest that aquaporins from ZmPIP2 subgroup may contribute to root water transfer by cellular pathway that occurs during the light and the dark period of the day-night cycle.
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Affiliation(s)
- Félicie Lopez
- Institut de Biotechnologie des Plantes, CNRS-UMR 8618, Bât. 630, Université Paris-Sud, F-91405 Orsay cedex, France
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Suga S, Murai M, Kuwagata T, Maeshima M. Differences in aquaporin levels among cell types of radish and measurement of osmotic water permeability of individual protoplasts. PLANT & CELL PHYSIOLOGY 2003; 44:277-286. [PMID: 12668774 DOI: 10.1093/pcp/pcg032] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We investigated tissue- and cell-specific accumulation of radish aquaporin isoforms by immunocytochemical analysis. In taproots, the plasma membrane aquaporins (RsPIP1 and RsPIP2) were accumulated at high levels in the cambium, while the tonoplast aquaporin (RsTIP) was distributed in all tissues. The three isoforms were highly accumulated in the central cylinder of seedling roots and hypocotyls, and rich in the vascular tissue of the petiole of mature plants. The results suggest that RsPIP1 and RsPIP2 are abundant in the cells surrounding the sieve tube of the radish plant. The swelling rate of protoplasts in a hypotonic solution was determined individually by a newly established method to compare the osmotic water permeability of different cell types. All cells of the cortex and endodermis in seedlings showed a high water permeability of more than 300 microm s(-1). There was no marked difference in the values between the root endodermis and cortex protoplasts, although the RsPIP level was lower in the cortex than in the endodermis. This inconsistency suggests two possibilities: (1) a low level of aquaporin is enough for high water permeability and (2) the water channel activity of aquaporin in the tissues is regulated individually. The uneven distribution of aquaporins in tissues is discussed along with their physiological roles.
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Affiliation(s)
- Shinobu Suga
- Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601 Japan
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Niemietz CM, Tyerman SD. New potent inhibitors of aquaporins: silver and gold compounds inhibit aquaporins of plant and human origin. FEBS Lett 2002; 531:443-7. [PMID: 12435590 DOI: 10.1016/s0014-5793(02)03581-0] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Silver and gold compounds were tested as potential inhibitors of aquaporins of plant- and human origin. Silver as AgNO(3) or silver sulfadiazine inhibited with high potency (EC(50) 1-10 microM) the water permeability of the peribacteroid membrane from soybean (containing Nodulin 26), the water permeability of plasma membrane from roots (containing plasma membrane integral proteins), and the water permeability of human red cells (containing aquaporin 1). Gold as HAuCl(4) was less effective but still inhibited peribacteroid membrane water permeability (EC(50)=10 microM). Silver and gold are more potent inhibitors of aquaporins than the presently widely used mercury containing compounds.
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Affiliation(s)
- Christa M Niemietz
- Department of Horticulture, Viticulture and Oenology, Adelaide University, Waite Campus, Private Mail Bag 1, 5064, Glen Osmond, SA, Australia.
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Maurel C, Javot H, Lauvergeat V, Gerbeau P, Tournaire C, Santoni V, Heyes J. Molecular physiology of aquaporins in plants. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 215:105-48. [PMID: 11952226 DOI: 10.1016/s0074-7696(02)15007-8] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In plants, membrane channels of the major intrinsic protein (MIP) super-family exhibit a high diversity with, for instance, 35 homologues in the model species Arabidopsis thaliana. As has been found in other organisms, plant MIPs function as membrane channels permeable to water (aquaporins) and in some cases to small nonelectrolytes. The aim of the present article is to integrate into plant physiology what has been recently learned about the molecular and functional properties of aquaporins in plants. Exhaustive compilation of data in the literature shows that the numerous aquaporin isoforms of plants have specific expression patterns throughout plant development and in response to environmental stimuli. The diversity of aquaporin homologues in plants can also be explained in part by their presence in multiple subcellular compartments. In recent years, there have been numerous reports that describe the activity of water channels in purified membrane vesicles, in isolated organelles or protoplasts, and in intact plant cells or even tissues. Altogether, these data suggest that the transport of water and solutes across plant membranes concerns many facets of plant physiology. Because of the high degree of compartmentation of plant cells, aquaporins may play a critical role in cell osmoregulation. Water uptake in roots represents a typical process in which to investigate the role of aquaporins in transcellular water transport, and the mechanisms and regulations involved are discussed.
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Affiliation(s)
- C Maurel
- Biochimie et Physiologie Moléculaire des Plantes, Agro-M/CNRS/INRA/UM2, Montpellier, France
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Engel A, Stahlberg H. Aquaglyceroporins: channel proteins with a conserved core, multiple functions, and variable surfaces. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 215:75-104. [PMID: 11952238 DOI: 10.1016/s0074-7696(02)15006-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Membrane channels for water and small nonionic solutes are required for osmoregulation in bacteria, plants, and animals. Aquaporin-1, the water channel of human erythrocytes, is the first channel demonstrated to conduct water, by expression in Xenopus oocytes. Phylogenetic analyses reveal the existence of two clusters of subfamilies, the aquaporins (AQPs) and glycerol facilitators (GLPs). Sequence-based structure prediction provided a model comprising six membrane-spanning helices, while sequence analyses suggested strategic residues that are important for structure and function. The surface topography of several AQPs has been mapped by atomic force microscopy, revealing different features that correlate with differences in the loops connecting transmembrane helices. The 3D structures of AQP1 and GlpF have been determined by electron cryomicroscopy. The 3.8-A density map allowed the first atomic model of AQP1 to be built, taking into account data from sequence analyses. This model provides some insight into the permeation of water through a channel that blocks the passage of protons. GIpF has been resolved to 6.9 A, revealing helices that are similar to those of AQP1. Homology modeling shows the channel region of these distant aquaglyceroporins to be similar, as confirmed by the 2.2-A structure of GlpF from X-ray crystallography.
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Affiliation(s)
- Andreas Engel
- M. E. Müller-Institute for Microscopic Structural Biology, Biozentrum, University of Basel, Switzerland
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35
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Abstract
Aquaporins are ubiquitous membrane channel proteins that facilitate and regulate the permeation of water across biological membranes. Aquaporins are members of the MIP family and some of them seem to be also able to transport other molecules such as urea or glycerol. In the plant kingdom, a single plant expresses a considerably large number of MIP homologues. These homologues can be subdivided into four groups (PIP, TIP, NIP, SIP) with highly conserved amino acid sequences and intron positions in each group. Since their discovery, advancing knowledge of their structure led to an understanding of the basic features of the water transport mechanism. An optimal water balance is essential to the homeostasis of most organisms, and aquaporins may be one of the mechanisms involved under changing environmental and developmental conditions. In fact, this may be one reason for the abundance and diversity of aquaporins, in particular in plants. In addition, exposure to different types of stress alters water relations and thus, aquaporins may be involved in stress responses as well. The transcriptional and/or post-translational regulation of aquaporins would determine changes in membrane water permeability. Both phosphorylation and translocation to/from vesicles have been reported as post-translational mechanisms. However, translocation in plants has not yet been shown. Although significant advances have been achieved, complete understanding of aquaporin function and regulation remains elusive.
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Affiliation(s)
- Isabel Baiges
- Unitat d'Enologia-CeRTA, Departament de Bioquímica i Biotecnologia, Facultat d'Enologia de Tarragona, Universitat Rovira i Virgili, Ramon y Cajal, 70. E-43005 Tarragona, Spain Institute of Biochemical Plant Pathology, GSF Research Centre for Environment and Health, Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
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Roudier N, Bailly P, Gane P, Lucien N, Gobin R, Cartron JP, Ripoche P. Erythroid expression and oligomeric state of the AQP3 protein. J Biol Chem 2002; 277:7664-9. [PMID: 11751877 DOI: 10.1074/jbc.m105411200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Biochemical and biophysical studies have shown that the strictly water-permeable aquaporins have a tetrameric structure, whereas results concerning the oligomeric state of GlpF, the glycerol facilitator of Escherichia coli, are dependent upon the analytical technique used. Here, we analyzed the oligomerization of the AQP3 aquaglyceroporin, which presents a mixed selectivity for water, glycerol, and urea. At first, based on transcript detection by reverse transcription-PCR from human erythroid tissues and membrane expression detected by flow cytometry analysis, we demonstrated that AQP3 is expressed on human and rat but not on mouse red blood cells. Then, the quaternary structure of AQP3 was determined using as models human red blood cell membranes, which carry both AQP1 and AQP3, and two heterologous expression systems: Xenopus laevis oocyte, for density and size estimation of aquaporins, and Saccharomyces cerevisiae yeast, which expressed a non-glycosylated form of AQP3. By velocity sedimentation in sucrose gradient after non-denaturing detergent solubilization, AQP3 was essentially found as mono- and dimeric species in conditions under which AQP1 preserved its tetrameric structure. Freeze-fracture studies on oocyte plasma membranes gave a size of AQP3 particles in favor of a dimeric or trimeric structure. Finally, by cross-linking experiments with red blood cell membranes, AQP3 is visible as different oligomeric structures, including a tetrameric one.
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Affiliation(s)
- Nathalie Roudier
- Département de Biologie Cellulaire et Moléculaire, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
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Tyerman SD, Niemietz CM, Bramley H. Plant aquaporins: multifunctional water and solute channels with expanding roles. PLANT, CELL & ENVIRONMENT 2002; 25:173-194. [PMID: 11841662 DOI: 10.1046/j.0016-8025.2001.00791.x] [Citation(s) in RCA: 293] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
There is strong evidence that aquaporins are central components in plant water relations. Plant species possess more aquaporin genes than species from other kingdoms. According to sequence similarities, four major groups have been identified, which can be further divided into subgroups that may correspond to localization and transport selectivity. They may be involved in compatible solute distribution, gas-transfer (CO2, NH3) as well as in micronutrient uptake (boric acid). Recent advances in determining the structure of some aquaporins gives further details on the mechanism of selectivity. Gating behaviour of aquaporins is poorly understood but evidence is mounting that phosphorylation, pH, pCa and osmotic gradients can affect water channel activity. Aquaporins are enriched in zones of fast cell division and expansion, or in areas where water flow or solute flux density would be expected to be high. This includes biotrophic interfaces between plants and parasites, between plants and symbiotic bacteria or fungi, and between germinating pollen and stigma. On a cellular level aquaporin clusters have been identified in some membranes. There is also a possibility that aquaporins in the endoplasmic reticulum may function in symplasmic transport if water can flow from cell to cell via the desmotubules in plasmodesmata. Functional characterization of aquaporins in the native membrane has raised doubt about the conclusiveness of expression patterns alone and need to be conducted in parallel. The challenge will be to elucidate gating on a molecular level and cellular level and to tie those findings into plant water relations on a macroscopic scale where various flow pathways need to be considered.
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Affiliation(s)
- S. D. Tyerman
- School of Biological Sciences, Flinders University Adelaide, GPO Box 2100, Adelaide SA 5001, Australia
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Quigley F, Rosenberg JM, Shachar-Hill Y, Bohnert HJ. From genome to function: the Arabidopsis aquaporins. Genome Biol 2002; 3:RESEARCH0001. [PMID: 11806824 PMCID: PMC150448 DOI: 10.1186/gb-2001-3-1-research0001] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2001] [Revised: 09/03/2001] [Accepted: 10/08/2001] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND In the post-genomic era newly sequenced genomes can be used to deduce organismal functions from our knowledge of other systems. Here we apply this approach to analyzing the aquaporin gene family in Arabidopsis thaliana. The aquaporins are intrinsic membrane proteins that have been characterized as facilitators of water flux. Originally termed major intrinsic proteins (MIPs), they are now also known as water channels, glycerol facilitators and aqua-glyceroporins, yet recent data suggest that they facilitate the movement of other low-molecular-weight metabolites as well. RESULTS The Arabidopsis genome contains 38 sequences with homology to aquaporin in four subfamilies, termed PIP, TIP, NIP and SIP. We have analyzed aquaporin family structure and expression using the A. thaliana genome sequence, and introduce a new NMR approach for the purpose of analyzing water movement in plant roots in vivo. CONCLUSIONS Our preliminary data indicate a strongly transcellular component for the flux of water in roots.
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Affiliation(s)
- Francoise Quigley
- Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, AZ 85721, USA.
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Abstract
Electron cryomicroscopy methods comprise a rapidly expanding field providing insights into the structure and function of biological macromolecules and their supramolecular assemblies. The 3.8 A resolution structure of the membrane protein aquaporin, a view of the herpesvirus capsid at 8.5 A and the 10 A resolution structure of the spliceosomal U1 small nuclear ribonucleoprotein complex are three outstanding examples emphasizing the versatility of this technique.
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Affiliation(s)
- V M Unger
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8024, USA.
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Werten PJ, Hasler L, Koenderink JB, Klaassen CH, de Grip WJ, Engel A, Deen PM. Large-scale purification of functional recombinant human aquaporin-2. FEBS Lett 2001; 504:200-5. [PMID: 11532454 DOI: 10.1016/s0014-5793(01)02703-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The homotetrameric aquaporin-2 (AQP2) water channel is essential for the concentration of urine and of critical importance in diseases with water dysregulation, such as nephrogenic diabetes insipidus, congestive heart failure, liver cirrhosis and pre-eclampsia. The structure of human AQP2 is a prerequisite for understanding its function and for designing specific blockers. To obtain sufficient amounts of AQP2 for structural analyses, we have expressed recombinant his-tagged human AQP2 (HT-AQP2) in the baculovirus/insect cell system. Using the protocols outlined in this study, 0.5 mg of pure HT-AQP2 could be obtained per liter of bioreactor culture. HT-AQP2 had retained its homotetrameric structure and exhibited a single channel water permeability of 0.93+/-0.03x10(-13) cm3/s, similar to that of other AQPs. Thus, the baculovirus/insect cell system allows large-scale expression of functional recombinant human AQP2 that is suitable for structural studies.
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Affiliation(s)
- P J Werten
- Department of Cell Physiology, University of Nijmegen, The Netherlands
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Mitra AK. Three-Dimensional Organization of the aquaporin water channel: what can structure tell us about function? VITAMINS AND HORMONES 2001; 62:133-66. [PMID: 11345897 DOI: 10.1016/s0083-6729(01)62003-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- A K Mitra
- Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037, USA
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Maeshima M. TONOPLAST TRANSPORTERS: Organization and Function. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY 2001; 52:469-497. [PMID: 11337406 DOI: 10.1146/annurev.arplant.52.1.469] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Regulation of the contents and volume of vacuoles in plant cells depends on the coordinated activities of transporters and channels located in the tonoplast (vacuolar membrane). The three major components of the tonoplast are two proton pumps, the vacuolar H+-ATPase (V-ATPase) and H+-pyrophosphatase (V-PPase), and aquaporins. The tertiary structure of the V-ATPase complex and properties of its subunits have been characterized by biochemical and genetic techniques. These studies and a comparison with the F-type ATPase have enabled estimation of the dynamics of V-ATPase activity during catalysis. V-PPase, a simple proton pump, has been identified and cloned from various plant species and other organisms, such as algae and phototrophic bacteria, and functional motifs of the enzyme have been determined. Aquaporin, serving as the water channel, is the most abundant protein in the tonoplast in most plants. A common molecular architecture of aquaporins in mammals and plants has been determined by two-dimensional crystallographic analysis. Furthermore, recent molecular biological studies have revealed several other types of tonoplast transporters, such as the Ca2+-ATPase, Ca2+/H+ antiporter and Na+/H+ antiporter. Many other transporters and channels in the tonoplast remain to be identified; their activities have already been detected. This review presents an overview of the field and discusses recent findings on the tonoplast protein components that have been identified and their physiological consequences.
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Affiliation(s)
- Masayoshi Maeshima
- Laboratory of Biochemistry, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; e-mail:
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Chaumont F, Barrieu F, Wojcik E, Chrispeels MJ, Jung R. Aquaporins constitute a large and highly divergent protein family in maize. PLANT PHYSIOLOGY 2001; 125:1206-15. [PMID: 11244102 PMCID: PMC65601 DOI: 10.1104/pp.125.3.1206] [Citation(s) in RCA: 390] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2000] [Revised: 12/18/2000] [Accepted: 12/19/2000] [Indexed: 05/18/2023]
Abstract
Aquaporins (AQPs) are an ancient family of channel proteins that transport water and neutral solutes through a pore and are found in all eukaryotes and most prokaryotes. A comparison of the amino acid sequences and phylogenetic analysis of 31 full-length cDNAs of maize (Zea mays) AQPs shows that they comprise four different groups of highly divergent proteins. We have classified them as plasma membrane intinsic proteins (PIPs), tonoplast intrinsic proteins, Nod26-like intrinsic proteins, and small and basic intrinsic proteins. Amino acid sequence identities vary from 16% to 100%, but all sequences share structural motifs and conserved amino acids necessary to stabilize the two loops that form the aqueous pore. Most divergent are the small and basic integral proteins in which the first of the two highly conserved Asn-Pro-Ala motifs of the pore is not conserved, but is represented by alanine-proline-threonine or alanine-proline-serine. We present a model of ZmPIP1-2 based on the three-dimensional structure of mammalian AQP1. Tabulation of the number of times that the AQP sequences are found in a collection of databases that comprises about 470,000 maize cDNAs indicates that a few of the maize AQPs are very highly expressed and many are not abundantly expressed. The phylogenetic analysis supports the interpretation that the divergence of PIPs through gene duplication occurred more recently than the divergence of the members of the other three subfamilies. This study opens the way to analyze the function of the proteins in Xenopus laevis oocytes, determine the tissue specific expression of the genes, recover insertion mutants, and determine the in planta function.
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Affiliation(s)
- F Chaumont
- Physiological Biochemistry, Université Catholique de Louvain, B-1348 Louvain-La-Neuve, Belgium
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44
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Stahlberg H, Heymann B, Mitsuoka K, Fuyijoshi Y, Engel A. Chapter 2 The aquaporin superfamily: Structure and function. CURRENT TOPICS IN MEMBRANES 2001. [DOI: 10.1016/s1063-5823(01)51004-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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45
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Chapter 7 Aquaporins of plants: Structure, function, regulation, and role in plant water relations. CURRENT TOPICS IN MEMBRANES 2001. [DOI: 10.1016/s1063-5823(01)51009-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Santoni V, Gerbeau P, Javot H, Maurel C. The high diversity of aquaporins reveals novel facets of plant membrane functions. CURRENT OPINION IN PLANT BIOLOGY 2000; 3:476-481. [PMID: 11074378 DOI: 10.1016/s1369-5266(00)00116-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The past year has brought significant advances in the characterisation in plants of a large class of water-channel proteins called aquaporins. The capacity of some of these proteins to transport small non-electrolytes in addition to water, together with their broad range of sub-cellular localisations, provides new clues to explain the great diversity of aquaporins in plants. Recent studies on water transport in roots illustrate how the variety of aquaporin functions at the tissue level is being uncovered.
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Affiliation(s)
- V Santoni
- Biochimie et Physiologie Moléculaire des Plantes, Institut National de la Recherche Agronomique (INRA), Centre Nationale de la Recherche Scientifique (CNRS), Montpellier, France.
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Braun T, Philippsen A, Wirtz S, Borgnia MJ, Agre P, Kühlbrandt W, Engel A, Stahlberg H. The 3.7 A projection map of the glycerol facilitator GlpF: a variant of the aquaporin tetramer. EMBO Rep 2000; 1:183-9. [PMID: 11265760 PMCID: PMC1084254 DOI: 10.1093/embo-reports/kvd022] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2000] [Revised: 05/05/2000] [Accepted: 06/05/2000] [Indexed: 11/15/2022] Open
Abstract
GlpF, the glycerol facilitator protein of Escherichia coli, is an archetypal member of the aquaporin superfamily. To assess its structure, recombinant histidine-tagged protein was overexpressed, solubilized in octylglucoside and purified to homogeneity. Negative stain electron microscopy of solubilized GlpF protein revealed a tetrameric structure of approximately 80 A side length. Scanning transmission electron microscopy yielded a mass of 170 kDa, corroborating the tetrameric nature of GlpF. Reconstitution of GlpF in the presence of lipids produced highly ordered two-dimensional crystals, which diffracted electrons to 3.6 A resolution. Cryoelectron microscopy provided a 3.7 A projection map exhibiting a unit cell comprised of two tetramers. In projection, GlpF is similar to AQP1, the erythrocyte water channel. However, the major density minimum within each monomer is distinctly larger in GlpF than in AQP1.
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Affiliation(s)
- T Braun
- ME Müller Institute for Microscopy, University of Basel, Switzerland
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Scheuring S, Tittmann P, Stahlberg H, Ringler P, Borgnia M, Agre P, Gross H, Engel A. The aquaporin sidedness revisited. J Mol Biol 2000; 299:1271-8. [PMID: 10873451 DOI: 10.1006/jmbi.2000.3811] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aquaporins are transmembrane water channel proteins, which play important functions in the osmoregulation and water balance of micro-organisms, plants, and animal tissues. All aquaporins studied to date are thought to be tetrameric assemblies of four subunits each containing its own aqueous pore. Moreover, the subunits contain an internal sequence repeat forming two obversely symmetric hemichannels predicted to resemble an hour-glass. This unique arrangement of two highly related protein domains oriented at 180 degrees to each other poses a significant challenge in the determination of sidedness. Aquaporin Z (AqpZ) from Escherichia coli was reconstituted into highly ordered two-dimensional crystals. They were freeze-dried and metal-shadowed to establish the relationship between surface structure and underlying protein density by electron microscopy. The shadowing of some surfaces was prevented by protruding aggregates. Thus, images collected from freeze-dried crystals that exhibited both metal-coated and uncoated regions allowed surface relief reconstructions and projection maps to be obtained from the same crystal. Cross-correlation peak searches along lattices crossing metal-coated and uncoated regions allowed an unambiguous alignment of the surface reliefs to the underlying density maps. AqpZ topographs previously determined by AFM could then be aligned with projection maps of AqpZ, and finally with human erythrocyte aquaporin-1 (AQP1). Thereby features of the AqpZ topography could be interpreted by direct comparison to the 6 A three-dimensional structure of AQP1. We conclude that the sidedness we originally proposed for aquaporin density maps was inverted.
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Affiliation(s)
- S Scheuring
- M. E. Müller Institute for Microscopy at the Biozentrum, University of Basel, Klingelbergstr. 70, Basel, CH-4056, Switzerland
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Engel A, Fujiyoshi Y, Agre P. The importance of aquaporin water channel protein structures. EMBO J 2000; 19:800-6. [PMID: 10698922 PMCID: PMC305620 DOI: 10.1093/emboj/19.5.800] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/1999] [Revised: 01/12/2000] [Accepted: 01/12/2000] [Indexed: 11/13/2022] Open
Abstract
The history of the water channel and recent structural and functional analyses of aquaporins are reviewed. These ubiquitous channels are important for bacteria, plants and animals, exhibit a pronounced sequence homology and share functional as well as structural similarities. Aquaporins allow water or small specific solutes to pass unhindered, but block the passage of ions to prevent dissipation of the transmembrane potential. Besides advances in structure determination, recent experiments suggest that many of these channels are regulated by pH variations, phosphorylation and binding of auxiliary proteins.
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Affiliation(s)
- A Engel
- M.E.Müller-Institute for Microscopy at the Biozentrum, University of Basel, CH-4056, Switzerland.
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