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Beratto-Ramos A, Dagnino-Leone J, Martínez-Oyanedel J, Fernández M, Aranda M, Bórquez R. Optimization of detergents in solubilization and reconstitution of Aquaporin Z: A structural approach. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184101. [PMID: 36535340 DOI: 10.1016/j.bbamem.2022.184101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 12/03/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
BACKGROUND The exceptional capacities of aquaporins in terms of water permeation and selectivity have made them an interesting system for membrane applications. Despite the multiple attempts for immobilizing the aquaporins over a porous substrate, there is a lack of studies related to the purification and reconstitution steps, principally associated with the use of detergents in solubilization and destabilization steps. This study analyzed the effect of detergents in Aquaporin Z solubilization, considering the purity and structural homogeneity of the protein. METHODS The extraction process was optimized by the addition of detergent at the sonication step, which enabled the omission of the ultracentrifugation and resuspension steps. Two detergents, Triton X-100, and octyl-glucoside were also evaluated. Destabilization mediated by detergents was used as reconstitution method. Saturation and solubilization points were defined by detergent concentration and both, liposomes and proteoliposomes, were analyzed by size distribution and permeability assays. Detergent removal with Bio-beads was also analyzed. RESULTS Octyl glucoside ensures structural stability and homogeneity of Aquaporin Z. However, high concentrations of detergents induce the presence of defects in proteoliposomes. While saturated liposomes create homogeneous and functional structures, solubilized liposomes get affected by a reassembly process, creating vesicle defects with anomalous permeability profiles. CONCLUSIONS Detergent concentration affects the structural conformation of proteoliposomes in the reconstitution process. GENERAL SIGNIFICANCE Since the destabilization process is dependent on vesicle, detergent, and buffer composition, optimization of this process should be mandatory for further studies. All these considerations will allow achieving the potential of Aquaporins and any other integral membrane protein in their applications for industrial purposes.
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Affiliation(s)
| | | | - José Martínez-Oyanedel
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
| | - Marcos Fernández
- Departamento de Farmacia, Facultad de Farmacia, Universidad de Concepción, Chile
| | - Mario Aranda
- Facultad de Química y de Farmacia, Pontificia Universidad Católica de Chile, Chile
| | - Rodrigo Bórquez
- Department of Chemical Engineering, Universidad de Concepción, Chile.
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2
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Drechsel V, Schneebauer G, Fiechtner B, Cutler CP, Pelster B. Aquaporin expression and cholesterol content in eel swimbladder tissue. JOURNAL OF FISH BIOLOGY 2022; 100:609-618. [PMID: 34882794 PMCID: PMC9302985 DOI: 10.1111/jfb.14973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 05/08/2023]
Abstract
Leakiness of the swimbladder wall of teleost fishes must be prevented to avoid diffusional loss of gases out of the swimbladder. Guanine incrustation as well as high concentrations of cholesterol in swimbladder membranes in midwater and deep-sea fish has been connected to a reduced gas permeability of the swimbladder wall. On the contrary, the swimbladder is filled by diffusion of gases, mainly oxygen and CO2 , from the blood and the gas gland cells into the swimbladder lumen. In swimbladder tissue of the zebrafish and the Japanese eel, aquaporin mRNA has been detected, and the aquaporin protein has been considered important for the diffusion of water, which may accidentally be gulped by physostome fish when taking an air breath. In the present study, the expression of two aquaporin 1 genes (Aqp1aa and Aqp1ab) in the swimbladder tissue of the European eel, a functional physoclist fish, was assessed using immunohistochemistry, and the expression of both genes was detected in endothelial cells of swimbladder capillaries as well as in basolateral membranes of gas gland cells. In addition, Aqp1ab was present in apical membranes of swimbladder gas gland cells. The authors also found high concentrations of cholesterol in these membranes, which were several fold higher than in muscle tissue membranes. In yellow eels the cholesterol concentration exceeded the concentration detected in silver eel swimbladder membranes. The authors suggest that aquaporin 1 in swimbladder gas gland cells and endothelial cells facilitates CO2 diffusion into the blood, enhancing the switch-on of the Root effect, which is essential for the secretion of oxygen into the swimbladder. It may also facilitate CO2 diffusion into the swimbladder lumen along the partial gradient established by CO2 production in gas gland cells. Cholesterol has been shown to reduce the gas permeability of membranes and thus could contribute to the gas tightness of swimbladder membranes, which is essential to avoid diffusional loss of gas out of the swimbladder.
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Affiliation(s)
- Victoria Drechsel
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Gabriel Schneebauer
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | - Birgit Fiechtner
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
| | | | - Bernd Pelster
- Institute of ZoologyUniversity of InnsbruckInnsbruckAustria
- Center for Molecular BiosciencesUniversity of InnsbruckInnsbruckAustria
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3
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Pellavio G, Laforenza U. Human sperm functioning is related to the aquaporin-mediated water and hydrogen peroxide transport regulation. Biochimie 2021; 188:45-51. [PMID: 34087390 DOI: 10.1016/j.biochi.2021.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/11/2021] [Accepted: 05/23/2021] [Indexed: 10/21/2022]
Abstract
Aquaporins (AQPs) are transmembrane water channels and some of them are permeable in addition to water to other small solutes including hydrogen peroxide. The sperm cells of mammals and fishes express different AQPs, although there is no agreement in the literature on their localization. In humans, AQP3 and AQP11 are expressed mainly in the tail, AQP7 in the head and AQP8 in the midpiece. Thanks to the results of experiments with KO mice and to data obtained by comparing sub-fertile patients with normospermic subjects, the importance of AQPs for the normal functioning of sperms to ensure normal fertility emerged. AQP3, AQP7 and AQP11 appeared involved in the sperm volume regulation, a key role for fertility because osmoadaptation protect the sperm against a swelling and tail bending that could affect sperm motility. AQP8 seems to have a fundamental role in regulating the elimination of hydrogen peroxide, the most abundant reactive oxygen species (ROS), and therefore in the response to oxidative stress. In this review, the human AQPs expression, their localization and functions, as well as their relevance in normal fertility are discussed. To understand better the AQPs role in human sperm functionality, the results of studies obtained in other animal species were also considered.
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Affiliation(s)
- Giorgia Pellavio
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, I-27100, Italy
| | - Umberto Laforenza
- Department of Molecular Medicine, Human Physiology Unit, University of Pavia, Pavia, I-27100, Italy.
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4
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Al-Samir S, Itel F, Hegermann J, Gros G, Tsiavaliaris G, Endeward V. O 2 permeability of lipid bilayers is low, but increases with membrane cholesterol. Cell Mol Life Sci 2021; 78:7649-7662. [PMID: 34694438 PMCID: PMC8629883 DOI: 10.1007/s00018-021-03974-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/06/2021] [Accepted: 10/12/2021] [Indexed: 11/18/2022]
Abstract
Oxygen on its transport route from lung to tissue mitochondria has to cross several cell membranes. The permeability value of membranes for O2 (PO2), although of fundamental importance, is controversial. Previous studies by mostly indirect methods diverge between 0.6 and 125 cm/s. Here, we use a most direct approach by observing transmembrane O2 fluxes out of 100 nm liposomes at defined transmembrane O2 gradients in a stopped-flow system. Due to the small size of the liposomes intra- as well as extraliposomal diffusion processes do not affect the overall kinetics of the O2 release process. We find, for cholesterol-free liposomes, the unexpectedly low PO2 value of 0.03 cm/s at 35 °C. This PO2 would present a serious obstacle to O2 entering or leaving the erythrocyte. Cholesterol turns out to be a novel major modifier of PO2, able to increase PO2 by an order of magnitude. With a membrane cholesterol of 45 mol% as it occurs in erythrocytes, PO2 rises to 0.2 cm/s at 35 °C. This PO2 is just sufficient to ensure complete O2 loading during passage of erythrocytes through the lung's capillary bed under the conditions of rest as well as maximal exercise.
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Affiliation(s)
- Samer Al-Samir
- AG Vegetative Physiologie 4220, Zentrum Physiologie, Medizinische Hochschule Hannover, 30625, Hannover, Germany
| | - Fabian Itel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstr. 5, CH-9014, St. Gallen, Switzerland
| | - Jan Hegermann
- Abteilung Funktionelle und Angewandte Anatomie, Elektronenmikroskopie 8840, Medizinische Hochschule Hannover, 30625, Hannover, Germany
| | - Gerolf Gros
- AG Vegetative Physiologie 4220, Zentrum Physiologie, Medizinische Hochschule Hannover, 30625, Hannover, Germany.
| | - Georgios Tsiavaliaris
- Abteilung Biophysikalische Chemie 4350, Medizinische Hochschule Hannover, 30625, Hannover, Germany
| | - Volker Endeward
- AG Vegetative Physiologie 4220, Zentrum Physiologie, Medizinische Hochschule Hannover, 30625, Hannover, Germany
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5
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Moss FJ, Mahinthichaichan P, Lodowski DT, Kowatz T, Tajkhorshid E, Engel A, Boron WF, Vahedi-Faridi A. Aquaporin-7: A Dynamic Aquaglyceroporin With Greater Water and Glycerol Permeability Than Its Bacterial Homolog GlpF. Front Physiol 2020; 11:728. [PMID: 32695023 PMCID: PMC7339978 DOI: 10.3389/fphys.2020.00728] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 06/04/2020] [Indexed: 12/27/2022] Open
Abstract
Xenopus oocytes expressing human aquaporin-7 (AQP7) exhibit greater osmotic water permeability and 3H-glycerol uptake vs. those expressing the bacterial glycerol facilitator GlpF. AQP7-expressing oocytes exposed to increasing extracellular [glycerol] under isosmolal conditions exhibit increasing swelling rates, whereas GlpF-expressing oocytes do not swell at all. To provide a structural basis for these observed physiological differences, we performed X-ray crystallographic structure determination of AQP7 and molecular-dynamics simulations on AQP7 and GlpF. The structure reveals AQP7 tetramers containing two monomers with 3 glycerols, and two monomers with 2 glycerols in the pore. In contrast to GlpF, no glycerol is bound at the AQP7 selectivity filter (SF), comprising residues F74, G222, Y223, and R229. The AQP7 SF is resolved in its closed state because F74 blocks the passage of small solutes. Molecular dynamics simulations demonstrate that F74 undergoes large and rapid conformational changes, allowing glycerol molecules to permeate without orientational restriction. The more rigid GlpF imposes orientational constraints on glycerol molecules passing through the SF. Moreover, GlpF-W48 (analogous to AQP7-F74) undergoes rare but long-lasting conformational changes that block the pore to H2O and glycerol.
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Affiliation(s)
- Fraser J. Moss
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Paween Mahinthichaichan
- Department of Biochemistry, Center for Biophysics and Quantitative Biology, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - David T. Lodowski
- Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Thomas Kowatz
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Emad Tajkhorshid
- Department of Biochemistry, Center for Biophysics and Quantitative Biology, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Andreas Engel
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Walter F. Boron
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
- Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Ardeschir Vahedi-Faridi
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
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6
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Abstract
Spontaneous solute and solvent permeation through membranes is of vital importance to human life, be it gas exchange in red blood cells, metabolite excretion, drug/toxin uptake, or water homeostasis. Knowledge of the underlying molecular mechanisms is the sine qua non of every functional assignment to membrane transporters. The basis of our current solubility diffusion model was laid by Meyer and Overton. It correlates the solubility of a substance in an organic phase with its membrane permeability. Since then, a wide range of studies challenging this rule have appeared. Commonly, the discrepancies have their origin in ill-used measurement approaches, as we demonstrate on the example of membrane CO2 transport. On the basis of the insight that scanning electrochemical microscopy offered into solute concentration distributions in immediate membrane vicinity of planar membranes, we analyzed the interplay between chemical reactions and diffusion for solvent transport, weak acid permeation, and enzymatic reactions adjacent to membranes. We conclude that buffer reactions must also be considered in spectroscopic investigations of weak acid transport in vesicular suspensions. The evaluation of energetic contributions to membrane translocation of charged species demonstrates the compatibility of the resulting membrane current with the solubility diffusion model. A local partition coefficient that depends on membrane penetration depth governs spontaneous membrane translocation of both charged and uncharged molecules. It is determined not only by the solubility in an organic phase but also by other factors like cholesterol concentration and intrinsic electric membrane potentials.
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Affiliation(s)
- Christof Hannesschlaeger
- From the Institute of Biophysics , Johannes Kepler University Linz , Gruberstrasse 40 , 4020 Linz , Austria
| | - Andreas Horner
- From the Institute of Biophysics , Johannes Kepler University Linz , Gruberstrasse 40 , 4020 Linz , Austria
| | - Peter Pohl
- From the Institute of Biophysics , Johannes Kepler University Linz , Gruberstrasse 40 , 4020 Linz , Austria
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7
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The Effect of Buffers on Weak Acid Uptake by Vesicles. Biomolecules 2019; 9:biom9020063. [PMID: 30781892 PMCID: PMC6406578 DOI: 10.3390/biom9020063] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/07/2019] [Accepted: 02/08/2019] [Indexed: 11/16/2022] Open
Abstract
The assessment of weak acid membrane permeability (Pm) frequently involves large unilamellar vesicles. It relies on measurements of the intravesicular pH drop, ΔpHin, in response to a sudden augmentation of external acid concentration. However, ΔpHin may be primarily governed by non-instantaneous protonation and deprotonation reactions of (i) the acid itself, (ii) the buffer molecules, and (iii) the fluorescent pH reporter dye. Moreover, buffer concentration and acid gradient also serve as determinants of ΔpHin, as we show here. The uniexponential time constant (τ) of ΔpHin(t) is an invalid measure of Pm as Arrhenius plots of Pm and τ reveal different activation energies for acid influx. We calculate Pm by fitting a mathematical model to experimental stopped-flow traces. The model takes into account not only the time course of total internal buffer capacity but also (i) water self-dissociation, (ii) volume changes due to acid induced osmotic water flow, and (iii) the spontaneous membrane proton leak. It allows extracting a Pm of 30.8 ± 3.5 μm/s for formic acid for 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) vesicles.
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8
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Arias-Hidalgo M, Al-Samir S, Gros G, Endeward V. Cholesterol is the main regulator of the carbon dioxide permeability of biological membranes. Am J Physiol Cell Physiol 2018; 315:C137-C140. [PMID: 29874108 DOI: 10.1152/ajpcell.00139.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We present here a compilation of membrane CO2 permeabilities (Pco2) for various cell types from the literature. Pco2 values vary over more than two orders of magnitude. Relating Pco2 to the cholesterol content of the membranes shows that, with the exception of red blood cells, it is essentially membrane cholesterol that determines the value of Pco2. Thus, the observed strong modulation of Pco2 in the majority of membranes is caused by cholesterol rather than gas channels.
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Affiliation(s)
- Mariela Arias-Hidalgo
- Institut für Molekular und Zellphysiologie, AG Vegetative Physiologie, Medizinische Hochschule Hannover, Hannover , Germany
| | - Samer Al-Samir
- Institut für Molekular und Zellphysiologie, AG Vegetative Physiologie, Medizinische Hochschule Hannover, Hannover , Germany
| | - Gerolf Gros
- Institut für Molekular und Zellphysiologie, AG Vegetative Physiologie, Medizinische Hochschule Hannover, Hannover , Germany
| | - Volker Endeward
- Institut für Molekular und Zellphysiologie, AG Vegetative Physiologie, Medizinische Hochschule Hannover, Hannover , Germany
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9
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CO₂ Permeability of Biological Membranes and Role of CO₂ Channels. MEMBRANES 2017; 7:membranes7040061. [PMID: 29064458 PMCID: PMC5746820 DOI: 10.3390/membranes7040061] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 10/13/2017] [Accepted: 10/18/2017] [Indexed: 01/09/2023]
Abstract
We summarize here, mainly for mammalian systems, the present knowledge of (a) the membrane CO₂ permeabilities in various tissues; (b) the physiological significance of the value of the CO₂ permeability;
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10
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Maeshima K, Yoshimoto M. Preparation and characterization of carbonic anhydrase-conjugated liposomes for catalytic synthesis of calcium carbonate particles. Enzyme Microb Technol 2017; 105:9-17. [PMID: 28756864 DOI: 10.1016/j.enzmictec.2017.06.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/15/2017] [Accepted: 06/03/2017] [Indexed: 11/27/2022]
Abstract
The biomimetic approach using immobilized enzymes is useful for the synthesis of structurally defined inorganic materials. In this work, carbonic anhydrase (CA) from bovine erythrocytes was covalently conjugated at 25°C to the liposomes composed of 15mol% 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine-N-(glutaryl) (NG-POPE), and the zwitterionic and anionic phospholipids with the same acyl chains as NG-POPE. For the conjugation, the carboxyl groups of liposomal NG-POPE were activated with 11mM 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 4.6mM N-hydroxysulfosuccinimide (sulfo-NHS). The carbonic anhydrase-conjugated liposomes (CALs) with the mean hydrodynamic diameter of 149nm showed the esterase activity corresponding to on average 5.5×102 free CA molecules per liposome. On the other hand, the intrinsic fluorescence and absorbance measurements consistently revealed that on average 1.4×103 CA molecules were conjugated to a liposome, suggesting that the molecular orientation of enzyme affected its activity. The formation of calcium carbonate particles was significantly accelerated by the CALs ([lipid]=50μ M) in the 0.3M Tris solution at 10-40°C with dissolved CO2 (≈17mM) and CaCl2 (46mM). The anionic CALs were adsorbed with calcium as revealed with the ζ-potential measurements. The CAL system offered the calcium-rich colloidal interface where the bicarbonate ions were catalytically produced by the liposome-conjugated CA molecules. The CALs also functioned in the external loop airlift bubble column operated with a model flue gas (10vol/vo% CO2), yielding partly agglomerated calcium carbonate particles as observed with the scanning electron microscopy (SEM).
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Affiliation(s)
- Keisuke Maeshima
- Department of Applied Molecular Bioscience, Yamaguchi University, Tokiwadai 2-16-1, Ube 755-8611, Japan
| | - Makoto Yoshimoto
- Department of Applied Molecular Bioscience, Yamaguchi University, Tokiwadai 2-16-1, Ube 755-8611, Japan.
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11
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Groszmann M, Osborn HL, Evans JR. Carbon dioxide and water transport through plant aquaporins. PLANT, CELL & ENVIRONMENT 2017; 40:938-961. [PMID: 27739588 DOI: 10.1111/pce.12844] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/01/2016] [Accepted: 09/22/2016] [Indexed: 05/25/2023]
Abstract
Aquaporins are channel proteins that function to increase the permeability of biological membranes. In plants, aquaporins are encoded by multigene families that have undergone substantial diversification in land plants. The plasma membrane intrinsic proteins (PIPs) subfamily of aquaporins is of particular interest given their potential to improve plant water relations and photosynthesis. Flowering plants have between 7 and 28 PIP genes. Their expression varies with tissue and cell type, through development and in response to a variety of factors, contributing to the dynamic and tissue specific control of permeability. There are a growing number of PIPs shown to act as water channels, but those altering membrane permeability to CO2 are more limited. The structural basis for selective substrate specificities has not yet been resolved, although a few key amino acid positions have been identified. Several regions important for dimerization, gating and trafficking are also known. PIP aquaporins assemble as tetramers and their properties depend on the monomeric composition. PIPs control water flux into and out of veins and stomatal guard cells and also increase membrane permeability to CO2 in mesophyll and stomatal guard cells. The latter increases the effectiveness of Rubisco and can potentially influence transpiration efficiency.
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Affiliation(s)
- Michael Groszmann
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Hannah L Osborn
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - John R Evans
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
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12
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Talbot K, Kwong RWM, Gilmour KM, Perry SF. The water channel aquaporin-1a1 facilitates movement of CO₂ and ammonia in zebrafish (Danio rerio) larvae. ACTA ACUST UNITED AC 2017; 218:3931-40. [PMID: 26677259 DOI: 10.1242/jeb.129759] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The present study tested the hypothesis that zebrafish (Danio rerio) aquaporin-1a1 (AQP1a1) serves as a multi-functional channel for the transfer of the small gaseous molecules, CO2 and ammonia, as well as water, across biological membranes. Zebrafish embryos were microinjected with a translation-blocking morpholino oligonucleotide targeted to AQP1a1. Knockdown of AQP1a1 significantly reduced rates of CO2 and ammonia excretion, as well as water fluxes, in larvae at 4 days post fertilization (dpf). Because AQP1a1 is expressed both in ionocytes present on the body surface and in red blood cells, the haemolytic agent phenylhydrazine was used to distinguish between the contributions of AQP1a1 to gas transfer in these two locations. Phenylhydrazine treatment had no effect on AQP1a1-linked excretion of CO2 or ammonia, providing evidence that AQP1a1 localized to the yolk sac epithelium, rather than red blood cell AQP1a1, is the major site of CO2 and ammonia movements. The possibility that AQP1a1 and the rhesus glycoprotein Rhcg1, which also serves as a dual CO2 and ammonia channel, act in concert to facilitate CO2 and ammonia excretion was explored. Although knockdown of each protein did not affect the abundance of mRNA and protein of the other protein under control conditions, impairment of ammonia excretion by chronic exposure to high external ammonia triggered a significant increase in the abundance of AQP1a1 mRNA and protein in 4 dpf larvae experiencing Rhcg1 knockdown. Collectively, these results suggest that AQP1a1 in zebrafish larvae facilitates the movement of CO2 and ammonia, as well as water, in a physiologically relevant fashion.
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Affiliation(s)
- Krystle Talbot
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Raymond W M Kwong
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Kathleen M Gilmour
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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13
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Cooper GJ, Occhipinti R, Boron WF. Rebuttal from Gordon J. Cooper, Rossana Occhipinti and Walter F. Boron. J Physiol 2015; 593:5033. [PMID: 26568430 DOI: 10.1113/jp271239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 09/22/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Gordon J Cooper
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Rossana Occhipinti
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Walter F Boron
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.,Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
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14
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Laforenza U, Bottino C, Gastaldi G. Mammalian aquaglyceroporin function in metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:1-11. [PMID: 26456554 DOI: 10.1016/j.bbamem.2015.10.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 11/26/2022]
Abstract
Aquaglyceroporins are integral membrane proteins that are permeable to glycerol as well as water. The movement of glycerol from a tissue/organ to the plasma and vice versa requires the presence of different aquaglyceroporins that can regulate the entrance or the exit of glycerol across the plasma membrane. Actually, different aquaglyceroporins have been discovered in the adipose tissue, small intestine, liver, kidney, heart, skeletal muscle, endocrine pancreas and capillary endothelium, and their differential expression could be related to obesity and the type 2 diabetes. Here we describe the expression and function of different aquaglyceroporins in physiological condition and in obesity and type 2 diabetes, suggesting they are potential therapeutic targets for metabolic disorders.
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Affiliation(s)
| | - Cinzia Bottino
- Department of Molecular Medicine, University of Pavia, Italy
| | - Giulia Gastaldi
- Department of Molecular Medicine, University of Pavia, Italy
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