Plant Aquaporins: Roles in Plant Physiology.

Biochimie et Physiologie Moléculaire des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, F-34060 Montpellier Cedex 2, France.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 11/2013; 1840(5). DOI: 10.1016/j.bbagen.2013.11.004
Source: PubMed


Aquaporins are membrane channels that facilitate the transport of water and small neutral molecules across biological membranes of most living organisms.
Here, we present comprehensive insights made on plant aquaporins in recent years, pointing to their molecular and physiological specificities with respect to animal or microbial counterparts.
In plants, aquaporins occur as multiple isoforms reflecting a high diversity of cellular localizations and various physiological substrates in addition to water. Of particular relevance for plants is the transport by aquaporins of dissolved gases such as carbon dioxide or metalloids such as boric or silicic acid. The mechanisms that determine the gating and subcellular localization of plant aquaporins are extensively studied. They allow aquaporin regulation in response to multiple environmental and hormonal stimuli. Thus, aquaporins play key roles in hydraulic regulation and nutrient transport in roots and leaves. They contribute to several plant growth and developmental processes such as seed germination or emergence of lateral roots.
Plants with genetically altered aquaporin functions are now tested for their ability to improve plant tolerance to stresses. This article is part of a Special Issue entitled Aquaporins.

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Available from: Guowei Li, Oct 25, 2014
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    • "The aim of this review is to provide a brief summary of such diversity. It is not intended to give a comprehensive review of aquaporin structural biology and physiology, since these aspects have recently been reviewed elsewhere (Abascal et al., 2014; Ahmadpour et al., 2014; Bienert and Chaumont, 2014; Day et al., 2014; Ishibashi et al., 2014; Kaldenhoff et al., 2014; Li et al., 2014; Mukhopadhyay et al., 2014; Song et al., 2014; Tani and Fujiyoshi, 2014). Therefore, we present a short overview of the structure and function of aquaporins, and include a section on prokaryotic aquaporins Received 15 April 2015; accepted 16 July 2015. "
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    ABSTRACT: In this review, we provide a brief synopsis of the evolution and functional diversity of the aquaporin gene superfamily in prokaryotic and eukaryotic organisms. Based upon the latest data, we discuss the expanding list of molecules shown to permeate the central pore of aquaporins, and the unexpected diversity of water channel genes in Archaea and Bacteria. We further provide new insight into the origin by horizontal gene transfer of plant glycerol-transporting aquaporins (NIPs), and the functional co-option and gene replacement of insect glycerol transporters. Finally, we discuss the origins of four major grades of aquaporins in Eukaryota, together with the increasing repertoires of aquaporins in vertebrates. © 2015 Marine Biological Laboratory.
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    • "Lipid auto-oxidation generates various ROS and causes seed deterioration at a moisture content <6%. Above a 14% moisture content, lipid oxidation may again be stimulated by the activity of hydrolytic oxidative enzymes (Labuza et al., 1972; Roberts and Ellis, 1989; McDonald, 1999; Shaban, 2013). Moreover, under a high moisture content, antioxidant enzymes (such as catalase, superoxide dismutase, and glutathione reductase) gradually lose activity and ROS will be accumulated (Bailly et al., 1996; Bailly, 2004). "
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    ABSTRACT: The tonoplast intrinsic proteins TIP3;1 and TIP3;2 are specifically expressed during seed maturation and localized to the seed protein storage vacuole membrane. However, the function and physiological roles of TIP3s are still largely unknown. The seed performance of TIP3 knockdown mutants was analysed using the controlled deterioration test. The tip3;1/tip3;2 double mutant was affected in seed longevity and accumulated high levels of hydrogen peroxide compared with the wild type, suggesting that TIP3s function in seed longevity. The transcription factor ABSCISIC ACID INSENSITIVE 3 (ABI3) is known to be involved in seed desiccation tolerance and seed longevity. TIP3 transcript and protein levels were significantly reduced in abi3-6 mutant seeds. TIP3;1 and TIP3;2 promoters could be activated by ABI3 in the presence of abscisic acid (ABA) in Arabidopsis protoplasts. TIP3 proteins were detected in the protoplasts transiently expressing ABI3 and in ABI3-overexpressing seedlings when treated with ABA. Furthermore, ABI3 directly binds to the RY motif of the TIP3 promoters. Therefore, seed-specific TIP3s may help maintain seed longevity under the expressional control of ABI3 during seed maturation and are members of the ABI3-mediated seed longevity pathway together with small heat shock proteins and late embryo abundant proteins. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.
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    • "In mammals, MIPs have a significant role in urinary concentration in the kidneys (Bockenhauer & Bichet, 2014; Nielsen et al., 2002), regulating the water fluxes into and out of brain (Badaut, Fukuda, Jullienne, & Petry, 2014; Papadopoulos & Verkman, 2007), follicle development in reproductive systems (Huang et al., 2006), skin hydration and elasticity (Hara, Ma, & Verkman, 2002; Lee et al., 2012), adipose metabolism (Kuriyama et al., 2002), maintaining corneal and lens transparency in the eye (Schey, Wang, Wenke, & Qi, 2014; Verkman, Ruiz-Ederra, & Levin, 2008), and lung edema ( Jin, Yu, Peng, Zhang, & Xin, 2013). In plants, MIPs seem to have diverse roles including leaf movement (Uehlein & Kaldenhoff, 2008), nutrient transport (Li, Santoni, et al., 2014), seed germination (Liu et al., 2013), hydraulic conductivity "
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    ABSTRACT: Members of the superfamily of major intrinsic proteins (MIPs) facilitate water and solute permeability across cell membranes and are found in sources ranging from bacteria to humans. Aquaporin and aquaglyceroporin channels are the prominent members of the MIP superfamily. Experimental studies show that MIPs are involved in important physiological processes in mammals and plants. They are implicated in several human diseases and are considered to be attractive drug targets for a wide range of diseases such as cancer, brain edema, epilepsy, glaucoma, and congestive heart failure. Three-dimensional structures of MIP channels from diverse sources reveal that MIPs adopt a unique conserved hourglass helical fold consisting of six transmembrane helices (TM1-TM6) and two half-helices (LB and LE). Conserved NPA motifs near the center and the aromatic/arginine selectivity filter (Ar/R SF) toward the extracellular side constitute two narrow constriction regions within the channel. Structural knowledge combined with simulation studies have helped to investigate the role of these two constriction regions in the transport and selectivity of the solutes. With the availability of many genome sequences from diverse species, a large number of MIP genes have been identified. Homology models of 1500 MIP channels have been used to derive structure-based sequence alignment of TM1-TM6 helices and the two half-helices LB and LE. Thirteen residues are highly conserved in different transmembrane helices and half-helices. High group conservation of small and weakly polar residues is observed in 27 positions at the interface of two interacting helices. Thus, although the MIP sequences are diverse, the hourglass helical fold is maintained during evolution with the conservation of these 40 positions within the transmembrane region. We have proposed a generic structure-based numbering scheme for the MIP channels that will facilitate easier comparison of the MIP sequences. Analysis of Ar/R SF in all 1500 MIPs indicates the extent of diversity in the four residues that form this narrow region. Certain residues are completely avoided in the SF, even if they have the same chemical nature as that of the most frequently observed residues. For example, arginine is the most preferred residue in a specific position of Ar/R SF, whereas lysine is almost always avoided in any of the four positions. MIP channels with highly hydrophobic or hydrophilic Ar/R SF have been identified. Similarly, there are examples of MIP channels in which all four residues of Ar/R SF are bulky, thus almost occluding the pore. Many plant MIPs possess small residues at all SF positions, resulting in a larger pore diameter. A majority of MIP channels are yet to be functionally characterized, and their in vivo substrates are not yet identified. A complete understanding of the relationship between the nature of Ar/R SF and the solutes that are transported is required to exploit MIP channels as potential drug targets. © 2015 Elsevier Inc. All rights reserved.
    Methods in enzymology 05/2015; 557:485-520. DOI:10.1016/bs.mie.2014.12.006 · 2.09 Impact Factor
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