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Fu L, Hu Y, Lin X, Wang Q, Yang L, Xin W, Zhou S, Qian Y, Kong XY, Jiang L, Wen L. Engineering Multi-field-coupled Synergistic Ion Transport System Based on the Heterogeneous Nanofluidic Membrane for High-Efficient Lithium Extraction. NANO-MICRO LETTERS 2023; 15:130. [PMID: 37209189 PMCID: PMC10200000 DOI: 10.1007/s40820-023-01106-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 04/13/2023] [Indexed: 05/22/2023]
Abstract
The global carbon neutrality strategy brings a wave of rechargeable lithium-ion batteries technique development and induces an ever-growing consumption and demand for lithium (Li). Among all the Li exploitation, extracting Li from spent LIBs would be a strategic and perspective approach, especially with the low energy consumption and eco-friendly membrane separation method. However, current membrane separation systems mainly focus on monotonous membrane design and structure optimization, and rarely further consider the coordination of inherent structure and applied external field, resulting in limited ion transport. Here, we propose a heterogeneous nanofluidic membrane as a platform for coupling multi-external fields (i.e., light-induced heat, electrical, and concentration gradient fields) to construct the multi-field-coupled synergistic ion transport system (MSITS) for Li-ion extraction from spent LIBs. The Li flux of the MSITS reaches 367.4 mmol m-2 h-1, even higher than the sum flux of those applied individual fields, reflecting synergistic enhancement for ion transport of the multi-field-coupled effect. Benefiting from the adaptation of membrane structure and multi-external fields, the proposed system exhibits ultrahigh selectivity with a Li+/Co2+ factor of 216,412, outperforming previous reports. MSITS based on nanofluidic membrane proves to be a promising ion transport strategy, as it could accelerate ion transmembrane transport and alleviate the ion concentration polarization effect. This work demonstrated a collaborative system equipped with an optimized membrane for high-efficient Li extraction, providing an expanded strategy to investigate the other membrane-based applications of their common similarities in core concepts.
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Affiliation(s)
- Lin Fu
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Yuhao Hu
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Xiangbin Lin
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Qingchen Wang
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Linsen Yang
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Weiwen Xin
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Shengyang Zhou
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Yongchao Qian
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
| | - Xiang-Yu Kong
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
| | - Lei Jiang
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Liping Wen
- CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, People's Republic of China.
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2
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Ling H, Xin W, Qian Y, He X, Yang L, Chen W, Wu Y, Du H, Liu Y, Kong XY, Jiang L, Wen L. Heterogeneous Electrospinning Nanofiber Membranes with pH-regulated Ion Gating for Tunable Osmotic Power Harvesting. Angew Chem Int Ed Engl 2023; 62:e202212120. [PMID: 36329000 DOI: 10.1002/anie.202212120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Indexed: 11/06/2022]
Abstract
Biological ion channels existing in organisms are critical for many biological processes. Inspired by biological ion channels, the heterogeneous electrospinning nanofiber membranes (HENM) with functional ion channels are constructed by electrospinning technology. The HENM successfully realizes ion-gating effects, which can be used for tunable energy conversions. Introduction of pyridine and carboxylic acid groups into the HENM plays an important role in generating unique and stable ion transport behaviors, in which gates become alternative states of open and close, responding to symmetric/asymmetric pH stimulations. Then we used the HENM to convert osmotic energy into electric energy which reach a maximum value up to 12.34 W m-2 and the output power density of HENM-based system could be regulated by ion-gating effects. The properties of the HENM provide widespread potentials in application of smart nanofluidic devices, energy conversion, and water treatment.
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Affiliation(s)
- Haoyang Ling
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Weiwen Xin
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yongchao Qian
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi, 710072, P. R. China
| | - Xiaofeng He
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Linsen Yang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Weipeng Chen
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Yadong Wu
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Huaqing Du
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yang Liu
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Xiang-Yu Kong
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Lei Jiang
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Liping Wen
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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3
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Zhou W, Yu T, Hua Y, Hou Y, Ding Y, Nie H. Effects of Hypoxia on Respiratory Diseases: Perspective View of Epithelial Ion Transport. Am J Physiol Lung Cell Mol Physiol 2022; 323:L240-L250. [PMID: 35819839 DOI: 10.1152/ajplung.00065.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The balance of gas exchange and lung ventilation is essential for the maintenance of body homeostasis. There are many ion channels and transporters in respiratory epithelial cells, including epithelial sodium channel, Na,K-ATPase, cystic fibrosis transmembrane conductance regulator, and some transporters. These ion channels/transporters maintain the capacity of liquid layer on the surface of respiratory epithelial cells, and provide an immune barrier for the respiratory system to clear off foreign pathogens. However, in some harmful external environment and/or pathological conditions, the respiratory epithelium is prone to hypoxia, which would destroy the ion transport function of the epithelium and unbalance the homeostasis of internal environment, triggering a series of pathological reactions. Many respiratory diseases associated with hypoxia manifest an increased expression of hypoxia-inducible factor-1, which mediates the integrity of the epithelial barrier and affects epithelial ion transport function. It is important to study the relationship between hypoxia and ion transport function, whereas the mechanism of hypoxia-induced ion transport dysfunction in respiratory diseases is not clear. This review focuses on the relationship of hypoxia and respiratory diseases, as well as dysfunction of ion transport and tight junctions in respiratory epithelial cells under hypoxia.
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Affiliation(s)
- Wei Zhou
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Tong Yu
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yu Hua
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yapeng Hou
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yan Ding
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Hongguang Nie
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
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Tsumoto K, Kurata Y. Bifurcations and Proarrhythmic Behaviors in Cardiac Electrical Excitations. Biomolecules 2022; 12:biom12030459. [PMID: 35327651 PMCID: PMC8946197 DOI: 10.3390/biom12030459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/09/2022] [Accepted: 03/14/2022] [Indexed: 12/23/2022] Open
Abstract
The heart is a hierarchical dynamic system consisting of molecules, cells, and tissues, and acts as a pump for blood circulation. The pumping function depends critically on the preceding electrical activity, and disturbances in the pattern of excitation propagation lead to cardiac arrhythmia and pump failure. Excitation phenomena in cardiomyocytes have been modeled as a nonlinear dynamical system. Because of the nonlinearity of excitation phenomena, the system dynamics could be complex, and various analyses have been performed to understand the complex dynamics. Understanding the mechanisms underlying proarrhythmic responses in the heart is crucial for developing new ways to prevent and control cardiac arrhythmias and resulting contractile dysfunction. When the heart changes to a pathological state over time, the action potential (AP) in cardiomyocytes may also change to a different state in shape and duration, often undergoing a qualitative change in behavior. Such a dynamic change is called bifurcation. In this review, we first summarize the contribution of ion channels and transporters to AP formation and our knowledge of ion-transport molecules, then briefly describe bifurcation theory for nonlinear dynamical systems, and finally detail its recent progress, focusing on the research that attempts to understand the developing mechanisms of abnormal excitations in cardiomyocytes from the perspective of bifurcation phenomena.
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5
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Hu JJ, Jiang W, Chen Q, Liu R, Lou X, Xia F. Solid-State Nanochannel with Multiple Signal Outputs for Furin Detection Based on the Biocompatible Condensation Reaction. Anal Chem 2021; 93:14036-14041. [PMID: 34633790 DOI: 10.1021/acs.analchem.1c03727] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Utilizing ionic current and fluorescent dual-signal-output nanochannels to achieve the detection of specific target species has received much attention. The introduction of an optical signal could not only improve the selectivity of the detection systems, but also make it possible to observe the reduction of the ionic current that originated from stimulus-triggered nanochannel changes. However, the resolution of an optical signal can only verify issues of the presence or absence and cannot precisely analyze the detailed chemical structural changes within nanochannels. Here, we employed a biocompatible condensation reaction between 2-cyanobenzothiazole (CBT) and d-cysteine, and synthesized molecules PCTC that can be polymerized by cutting off short peptide sequences in the presence of furin to realize the detection of furin with multiple signal outputs. Through the introduction of a UV light-sensitive DNA sequence to the capture probes (CPs) inside the nanochannels, the blocking of the nanochannels can be confirmed to the formed oligomers by mass spectrometry analysis.
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Affiliation(s)
- Jing-Jing Hu
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
| | - Wenlian Jiang
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
| | - Qing Chen
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
| | - Rui Liu
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
| | - Xiaoding Lou
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, China
- Zhejiang Institute, China University of Geosciences, Hangzhou, 311305, China
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6
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ATP1A3 mutation as a candidate cause of autosomal dominant cone-rod dystrophy. Hum Genet 2020; 139:1391-1401. [PMID: 32440726 DOI: 10.1007/s00439-020-02182-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/08/2020] [Indexed: 10/24/2022]
Abstract
Cone-rod dystrophy (CORD) is an inherited retinal degenerative disease characterized by progressive loss of cone and rod photoreceptors. Although several genes have been reported to cause autosomal dominant CORD (adCORD), the genetic causes of adCORD have not been fully elucidated. Here, we identified the ATP1A3 gene, encoding the α3 subunit of Na+, K+-ATPase, as a novel gene associated with adCORD. Using whole-exome sequencing (WES), we found a candidate mutation of ATP1A3 that co-segregated with the disease in an analysis of two affected patients and one healthy relative in an adCORD family. According to our RNA-seq data, we demonstrated that the Atp1a3 mRNA level was extremely high in the murine retina. Overexpression of mutant ATP1A3 in vitro led to a reduced oxygen consumption rate (OCR), reflecting the limited mitochondrial reserve capacity. Furthermore, we generated transgenic mice expressing the ATP1A3 cDNA with patient variant and found decreased electroretinogram (ERG) responses. Moreover, the mutant ATP1A3 is highly expressed in photoreceptor inner segment, where mitochondria are enriched. These results suggest that the ATP1A3 mutation is a new genetic cause responsible for adCORD and indicate that ATP1A3 plays an important role in retinal function.
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7
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Hsu JP, Chen YM, Lin CY, Tseng S. Electrokinetic ion transport in an asymmetric double-gated nanochannel with a pH-tunable zwitterionic surface. Phys Chem Chem Phys 2019; 21:7773-7780. [PMID: 30918928 DOI: 10.1039/c9cp00266a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bioinspired, artificial functional nanochannels for intelligent molecular and ionic transport control have versatile potential applications in nanofluidics, energy conversion, and controlled drug release. To simulate the gating and rectification functions of biological ion channels, we model the electrokinetic ion transport phenomenon in an asymmetric double-gated nanochannel having a pH-regulated, zwitterionic surface. Taking account of the effect of electroosmotic flow (EOF), the conductance of the nanochannel and its ion current rectification (ICR) behavior are investigated and the associated mechanisms interpreted. In particular, the influences of the solution pH, the bulk salt concentration, and the base opening radius and the surface curvature of the nanochannel on these behaviors are examined. We show that through adjusting the base opening radius and the surface curvature of a nanochannel, its ICR behavior can be tuned effectively. In addition to proposing underlying mechanisms for the phenomena observed, the results gathered in this study also provide necessary information for designing relevant devices.
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Affiliation(s)
- Jyh-Ping Hsu
- Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan.
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8
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Câmara DR, Kastelic JP, Thundathil JC. Role of the Na +/K +-ATPase ion pump in male reproduction and embryo development. Reprod Fertil Dev 2018; 29:1457-1467. [PMID: 27456939 DOI: 10.1071/rd16091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/19/2016] [Indexed: 12/18/2022] Open
Abstract
Na+/K+-ATPase was one of the first ion pumps studied because of its importance in maintaining osmotic and ionic balances between intracellular and extracellular environments, through the exchange of three Na+ ions out and two K+ ions into a cell. This enzyme, which comprises two main subunits (α and β), with or without an auxiliary polypeptide (γ), can have specific biochemical properties depending on the expression of associated isoforms (α1β1 and/or α2β1) in the cell. In addition to the importance of Na+/K+-ATPase in ensuring the function of many tissues (e.g. brain, heart and kidney), in the reproductive tract this protein is essential for embryo development because of its roles in blastocoel formation and embryo hatching. In the context of male reproduction, the discovery of a very specific subunit (α4), apparently restricted to male germ cells, only expressed after puberty and able to influence sperm function (e.g. motility and capacitation), opened a remarkable field for further investigations regarding sperm biology. Therefore, the present review focuses on the importance of Na+/K+-ATPase on male reproduction and embryo development.
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Affiliation(s)
- D R Câmara
- Faculdade de Medicina Veterinária, Universidade Federal de Alagoas, Fazenda São Luiz, s/n, Zona Rural do Município de Viçosa, Viçosa-AL, CEP: 57700-000, Brazil
| | - J P Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Dr., NW, Calgary, AB T2N 4N1, Canada
| | - J C Thundathil
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Dr., NW, Calgary, AB T2N 4N1, Canada
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9
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Wu Y, Wang D, Willner I, Tian Y, Jiang L. Smart DNA Hydrogel Integrated Nanochannels with High Ion Flux and Adjustable Selective Ionic Transport. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803222] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yafeng Wu
- School of Chemistry and Chemical Engineering; Southeast University; Nanjing 211189 China
- Laboratory of Bioinspired Smart Interfacial Science; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
| | - Dianyu Wang
- Jilin University; College of Chemistry; Changchun 130012 P. R. China
| | - Itamar Willner
- Institute of Chemistry; The Minerva Center for Complex Biohybrid Systems; The Hebrew University of Jerusalem; Jerusalem 91904 Israel
| | - Ye Tian
- Beijing National Laboratory for Molecular Sciences (BNLMS); Key Laboratory of Organic Solids; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
| | - Lei Jiang
- Laboratory of Bioinspired Smart Interfacial Science; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
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10
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Wu Y, Wang D, Willner I, Tian Y, Jiang L. Smart DNA Hydrogel Integrated Nanochannels with High Ion Flux and Adjustable Selective Ionic Transport. Angew Chem Int Ed Engl 2018; 57:7790-7794. [DOI: 10.1002/anie.201803222] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Yafeng Wu
- School of Chemistry and Chemical Engineering; Southeast University; Nanjing 211189 China
- Laboratory of Bioinspired Smart Interfacial Science; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
| | - Dianyu Wang
- Jilin University; College of Chemistry; Changchun 130012 P. R. China
| | - Itamar Willner
- Institute of Chemistry; The Minerva Center for Complex Biohybrid Systems; The Hebrew University of Jerusalem; Jerusalem 91904 Israel
| | - Ye Tian
- Beijing National Laboratory for Molecular Sciences (BNLMS); Key Laboratory of Organic Solids; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
| | - Lei Jiang
- Laboratory of Bioinspired Smart Interfacial Science; Technical Institute of Physics and Chemistry; Chinese Academy of Sciences; Beijing 100190 P. R. China
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11
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Cheng MH, Torres-Salazar D, Gonzalez-Suarez AD, Amara SG, Bahar I. Substrate transport and anion permeation proceed through distinct pathways in glutamate transporters. eLife 2017; 6. [PMID: 28569666 PMCID: PMC5472439 DOI: 10.7554/elife.25850] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/10/2017] [Indexed: 11/13/2022] Open
Abstract
Advances in structure-function analyses and computational biology have enabled a deeper understanding of how excitatory amino acid transporters (EAATs) mediate chloride permeation and substrate transport. However, the mechanism of structural coupling between these functions remains to be established. Using a combination of molecular modeling, substituted cysteine accessibility, electrophysiology and glutamate uptake assays, we identified a chloride-channeling conformer, iChS, transiently accessible as EAAT1 reconfigures from substrate/ion-loaded into a substrate-releasing conformer. Opening of the anion permeation path in this iChS is controlled by the elevator-like movement of the substrate-binding core, along with its wall that simultaneously lines the anion permeation path (global); and repacking of a cluster of hydrophobic residues near the extracellular vestibule (local). Moreover, our results demonstrate that stabilization of iChS by chemical modifications favors anion channeling at the expense of substrate transport, suggesting a mutually exclusive regulation mediated by the movement of the flexible wall lining the two regions.
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Affiliation(s)
- Mary Hongying Cheng
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
| | - Delany Torres-Salazar
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Aneysis D Gonzalez-Suarez
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Ivet Bahar
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
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12
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13
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Zhang Z, Kong XY, Xie G, Li P, Xiao K, Wen L, Jiang L. "Uphill" cation transport: A bioinspired photo-driven ion pump. SCIENCE ADVANCES 2016; 2:e1600689. [PMID: 27774511 PMCID: PMC5072182 DOI: 10.1126/sciadv.1600689] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 09/22/2016] [Indexed: 05/26/2023]
Abstract
Biological ion pumps with active ionic transport properties lay the foundation for many life processes. However, few analogs have been produced because extra energy is needed to couple to this "uphill" process. We demonstrate a bioinspired artificial photo-driven ion pump based on a single polyethylene terephthalate conical nanochannel. The pumping process behaving as an inversion of zero-volt current can be realized by applying ultraviolet irradiation from the large opening. The light energy can accelerate the dissociation of the benzoic acid derivative dimers existing on the inner surface of nanochannel, which consequently produces more mobile carboxyl groups. Enhanced electrostatic interaction between the ions traversing the nanochannel and the charged groups on the inner wall is the key reason for the uphill cation transport behavior. This system creates an ideal experimental and theoretical platform for further development and design of various stimuli-driven and specific ion-selective bioinspired ion pumps, which anticipates wide potential applications in biosensing, energy conversion, and desalination.
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Affiliation(s)
- Zhen Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Xiang-Yu Kong
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Ganhua Xie
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Pei Li
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Kai Xiao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Liping Wen
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
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14
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Cai SL, Zheng YB, Cao SH, Cai XH, Li YQ. A conformation and charge co-modulated ultrasensitive biomimetic ion channel. Chem Commun (Camb) 2016; 52:12450-12453. [DOI: 10.1039/c6cc04899d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For the first time, an ultrasensitive nanopore-based sensor that co-modulated simultaneously by conformation and charge has been developed for the detection of ATP.
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Affiliation(s)
- Sheng-Lin Cai
- Department of Chemistry and Key Laboratory of Analytical Sciences
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
- P. R. China
| | - Yu-Bin Zheng
- Department of Chemistry and Key Laboratory of Analytical Sciences
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
- P. R. China
| | - Shuo-Hui Cao
- Department of Chemistry and Key Laboratory of Analytical Sciences
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
- P. R. China
| | - Xiu-Hong Cai
- Department of Chemistry and Key Laboratory of Analytical Sciences
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
- P. R. China
| | - Yao-Qun Li
- Department of Chemistry and Key Laboratory of Analytical Sciences
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
- P. R. China
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15
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Abstract
Work done by Bennett et al. [ Nature 2002 , 420 , 398 - 401 ] demonstrated that Ca(2+) ions can be actively transported through a lipid bilayer membrane by an artificial photosynthetic machine. However, details of the pump process, such as the oxidation state of the shuttle molecule and stoichiometry of the shuttle-ion complex, are not fully understood, which hinders the development of ion pumps of this type with higher efficiency. In this study, we combine all atom molecular dynamics simulations and quantum mechanics calculations to estimate the time scale of the shuttle-ion complex diffusion process and charge transfer step. We find that the process of shuttle-ion complex diffusion across the lipid bilayer membrane is the rate-limiting step, with a time scale of seconds to minutes. Other processes such as charge transfer between the redox reaction center and the shuttle molecule have picoseconds time scales. We also show that a shuttle-ion complex with 2:1 stoichiometry ratio has a lower energy barrier across the lipid membrane than other choices of complexes. The calculations show that the Ca(2+) ion is likely to be shuttled by a semiquinone type of shuttle molecule as this has the lowest free energy barrier across the lipid bilayer membrane, the fewest electrons transferred in the redox cycle, and it does not generate (or require) proton flow. Estimates of ion flow rates are consistent with measured values.
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Affiliation(s)
- Cheng-Tsung Lai
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Yu Zhang
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.,Center for Bioinspired Energy Science, Northwestern University , Chicago, Illinois 60611, United States
| | - George C Schatz
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.,Center for Bioinspired Energy Science, Northwestern University , Chicago, Illinois 60611, United States
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16
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Abstract
The Na+/K+-ATPase restores sodium
(Na+) and potassium (K+)
electrochemical gradients dissipated by action potentials and ion-coupled transport
processes. As ions are transported, they become transiently trapped between
intracellular and extracellular gates. Once the external gate opens, three
Na+ ions are released, followed by the binding and
occlusion of two K+ ions. While the mechanisms of
Na+ release have been well characterized by the study of
transient Na+ currents, smaller and faster transient
currents mediated by external K+ have been more difficult to
study. Here we show that external K+ ions travelling to
their binding sites sense only a small fraction of the electric field as they
rapidly and simultaneously become occluded. Consistent with these results, molecular
dynamics simulations of a pump model show a wide water-filled access channel
connecting the binding site to the external solution. These results suggest a
mechanism of K+ gating different from that of
Na+ occlusion. During transport by the
Na+/K+-ATPase,
Na+ and K+ ions become occluded
between intra- and extracellular gates. Here Castillo et al. measure transient
electrical signals arising from K+ occlusion and use molecular
simulations to describe a K+ gating mechanism fundamentally
different to that of Na+.
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17
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Abstract
When the Na,K-ATPase pumps at each turnover two K(+) ions into the cytoplasm, this translocation consists of several reaction steps. First, the ions diffuse consecutively from the extracellular phase through an access pathway to the binding sites where they are coordinated. In the next step, the enzyme is dephosphorylated and the ions are occluded inside the membrane domain. The subsequent transition to the E1 conformation produces a deocclusion of the binding sites to the cytoplasmic side of the membrane and allows in the last steps ion dissociation and diffusion to the aqueous phase. The interaction and competition of K(+) with various quaternary organic ammonium ions have been used to gain insight into the molecular mechanism of the ion binding process from the extracellular side in the P-E2 conformation of the enzyme. Using the electrochromic styryl dye RH421, evidence has been obtained that the access pathway consists of a wide and water-filled funnel-like part that is accessible also for bulky cations such as the benzyltriethylammonium ion, and a narrow part that permits passage only of small cations such as K(+) and NH4(+) in a distinct electrogenic way. Benzyltriethylammonium ions inhibit K(+) binding in a competitive manner that can be explained by a stopper-like function at the interface between the wide and narrow parts of the access pathway. In contrast to other quaternary organic ammonium ions, benzyltriethylammonium ions show a specific binding to the ion pump in a position inside the access pathway where it blocks effectively the access to the binding sites.
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Affiliation(s)
| | - Hans-Jürgen Apell
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
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18
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Opoku-Okrah C, Acquah BKS, Dogbe EE. Changes in potassium and sodium concentrations in stored blood. Pan Afr Med J 2015; 20:236. [PMID: 27386032 PMCID: PMC4919675 DOI: 10.11604/pamj.2015.20.236.5851] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/13/2015] [Indexed: 01/10/2023] Open
Abstract
Potassium is the principal intracellular cation with sodium being the principal extracellular cation. Maintenance of the distribution of potassium and sodium between the intracellular and the extracellular compartments relies on several homeostatic mechanisms. This study analysed the effect of blood storage on the concentrations of potassium and sodium in stored blood and also determine any variations that may exist in their concentrations. 50 mls of blood was sampled each from 28 units of evenly mixed donated blood in citrate phosphate dextrose adenine (CPDA-1) bags immediately after donation into satellite bag and stored at 4oC. Potassium and sodium concentration determinations were done on each of the 28 samples on day 0 (before blood was initially stored in the fridge), day 5, day 10, day 15 and day 20 of storage using the Roche 9180 ISE Electrolyte Analyser (Hoffmann-La Roche Ltd, Switzerland). data analysis showed significant changes in the potassium and sodium concentrations with a continuous rise in potassium and a continuous fall in sodium. A daily change of 0.59 mmol/l and 0.50 mmol/l was observed in the potassium and sodium concentrations respectively. We showed steady but increased daily concentrations of potassium and decrease concentrations of sodium in blood stored over time at 4oC.
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Affiliation(s)
- Clement Opoku-Okrah
- Department of Medical Laboratory Technology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Benjamin Kojo Safo Acquah
- Department of Medical Laboratory Technology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Elliot Eli Dogbe
- Transfusion Medicine Unit, Komfo Anokye Teaching Hospital, Kumasi, Ghana
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19
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Vedovato N, Gadsby DC. Route, mechanism, and implications of proton import during Na+/K+ exchange by native Na+/K+-ATPase pumps. ACTA ACUST UNITED AC 2014; 143:449-64. [PMID: 24688018 PMCID: PMC3971657 DOI: 10.1085/jgp.201311148] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The Na+/K+ pump is a hybrid transporter that can also import protons at physiological K+ and Na+ concentrations. A single Na+/K+-ATPase pumps three Na+ outwards and two K+ inwards by alternately exposing ion-binding sites to opposite sides of the membrane in a conformational sequence coupled to pump autophosphorylation from ATP and auto-dephosphorylation. The larger flow of Na+ than K+ generates outward current across the cell membrane. Less well understood is the ability of Na+/K+ pumps to generate an inward current of protons. Originally noted in pumps deprived of external K+ and Na+ ions, as inward current at negative membrane potentials that becomes amplified when external pH is lowered, this proton current is generally viewed as an artifact of those unnatural conditions. We demonstrate here that this inward current also flows at physiological K+ and Na+ concentrations. We show that protons exploit ready reversibility of conformational changes associated with extracellular Na+ release from phosphorylated Na+/K+ pumps. Reversal of a subset of these transitions allows an extracellular proton to bind an acidic side chain and to be subsequently released to the cytoplasm. This back-step of phosphorylated Na+/K+ pumps that enables proton import is not required for completion of the 3 Na+/2 K+ transport cycle. However, the back-step occurs readily during Na+/K+ transport when external K+ ion binding and occlusion are delayed, and it occurs more frequently when lowered extracellular pH raises the probability of protonation of the externally accessible carboxylate side chain. The proton route passes through the Na+-selective binding site III and is distinct from the principal pathway traversed by the majority of transported Na+ and K+ ions that passes through binding site II. The inferred occurrence of Na+/K+ exchange and H+ import during the same conformational cycle of a single molecule identifies the Na+/K+ pump as a hybrid transporter. Whether Na+/K+ pump–mediated proton inflow may have any physiological or pathophysiological significance remains to be clarified.
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Affiliation(s)
- Natascia Vedovato
- The Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, NY 10065
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20
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Cui H, Li L, Wang W, Shen J, Yue Z, Zheng X, Zuo X, Liang B, Gao M, Fan X, Yin X, Shen C, Yang C, Zhang C, Zhang X, Sheng Y, Gao J, Zhu Z, Lin D, Zhang A, Wang Z, Liu S, Sun L, Yang S, Cui Y, Zhang X. Exome sequencing identifies SLC17A9 pathogenic gene in two Chinese pedigrees with disseminated superficial actinic porokeratosis. J Med Genet 2014; 51:699-704. [PMID: 25180256 DOI: 10.1136/jmedgenet-2014-102486] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Disseminated superficial actinic porokeratosis (DSAP) is a rare autosomal dominant genodermatosis characterised by annular lesions that has an atrophic centre and a prominent peripheral ridge distributed on sun exposed area. It exhibits high heterogeneity, and five linkage loci have been reported. The mevalonate kinase (MVK) gene located on 12q24 has been confirmed as one of the disease-causing genes. But, the pathogenesis of a large part of DSAP remains unclear so far. METHODS The recruited with DSAP carried no MVK coding mutations. Exome sequencing was performed in two affected and one unaffected individual in Family 1. Cosegregation of the candidate variants was tested in other family members. Sanger sequencing in 33 individuals with familial DSAP and 19 sporadic DSAP individuals was performed for validating the causative gene. RESULTS An average of 1.35×10(5) variants were generated from exome data and 133 novel NS/SS/indels were identified as being shared by two affected individuals but absent in the unaffected individual. After functional prediction, 25 possible deleterious variants were identified. In Family 1, a missense variant c.932G>A (p.Arg311Gln) in exon 10 of SLC17A9 was observed in cosegregation with the phenotype; this amino acid substitution was located in a highly conserved major facilitator superfamily (MFS) domain in multiple mammalian. One additional missense variant c.25C>T (p.Arg9Cys) in exon 2 of SLC17A9 was found in Family 2. CONCLUSIONS The result identified SLC17A9 as another pathogenic gene for DSAP, which suggests a correlation between the aberrant vesicular nucleotide transporter and the pathogenesis of DSAP.
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Affiliation(s)
- Hongzhou Cui
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology, Huashan Hospital of Fudan University, Shanghai, China Department of Dermatology at No.2 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Longnian Li
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Wenjun Wang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Jie Shen
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Zhen Yue
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Xiaodong Zheng
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Xianbo Zuo
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Bo Liang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Min Gao
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Xing Fan
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Xianyong Yin
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Changbing Shen
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Chao Yang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Change Zhang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Xiaoguang Zhang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Yujun Sheng
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Jinping Gao
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Zhengwei Zhu
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Da Lin
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Anping Zhang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Zaixing Wang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Shengxiu Liu
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Liangdan Sun
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Sen Yang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology, Huashan Hospital of Fudan University, Shanghai, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Yong Cui
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
| | - Xuejun Zhang
- Institute of Dermatology and Department of Dermatology at No.1 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology, Huashan Hospital of Fudan University, Shanghai, China Department of Dermatology at No.2 Hospital, Anhui Medical University, Hefei, Anhui, China Department of Dermatology and Venereology, Anhui Medical University, Hefei, Anhui, China State Key Laboratory Incubation Base of Dermatology, Ministry of National Science and Technology & Key Laboratory of Dermatology, Ministry of Education & Key Laboratory of Dermatology, Hefei, Anhui, China
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21
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Hilgemann DW. Fishing for holes in transporters: how protons breach the Na/K pump security gates. ACTA ACUST UNITED AC 2014; 143:437-41. [PMID: 24688016 PMCID: PMC3971659 DOI: 10.1085/jgp.201411189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Donald W Hilgemann
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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22
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Zhang H, Hou X, Zeng L, Yang F, Li L, Yan D, Tian Y, Jiang L. Bioinspired Artificial Single Ion Pump. J Am Chem Soc 2013; 135:16102-10. [DOI: 10.1021/ja4037669] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Huacheng Zhang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Xu Hou
- National Center for Nanoscience and Technology, Beijing 100190, P. R.
China
| | | | | | | | | | - Ye Tian
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Lei Jiang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Organic Solids,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
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23
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Heasley B. Chemical synthesis of the cardiotonic steroid glycosides and related natural products. Chemistry 2012; 18:3092-120. [PMID: 22354477 DOI: 10.1002/chem.201103733] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The active components from the extracts of Digitalis, cardiotonic steroid glycosides, have been ingested by humans for more than 200 years as a medicinal therapy for heart failure and abnormal heart rhythms. The positive inotropic activity of the cardiotonic steroids that mediates clinically useful physiological effects in patients has been attributed largely to a high affinity inhibitory interaction with the extracellular surface of the membrane-bound sodium pump (Na(+)/K(+)-ATPase). However, previously unrecognized intracellular signaling pathways continue to be uncovered. This Review examines both partial and de novo synthetic approaches to the medicinally important and structurally captivating cardenolide and bufadienolide steroid families, with an emphasis on the stereocontrolled construction of the pharmacophoric aglycone (genin) framework.
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Affiliation(s)
- Brian Heasley
- Scynexis, Inc. P. O. Box 12878, Research Triangle Park, NC 27709-2878, USA.
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24
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Mechanism of proton/substrate coupling in the heptahelical lysosomal transporter cystinosin. Proc Natl Acad Sci U S A 2012; 109:E210-7. [PMID: 22232659 DOI: 10.1073/pnas.1115581109] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Secondary active transporters use electrochemical gradients provided by primary ion pumps to translocate metabolites or drugs "uphill" across membranes. Here we report the ion-coupling mechanism of cystinosin, an unusual eukaryotic, proton-driven transporter distantly related to the proton pump bacteriorhodopsin. In humans, cystinosin exports the proteolysis-derived dimeric amino acid cystine from lysosomes and is impaired in cystinosis. Using voltage-dependence analysis of steady-state and transient currents elicited by cystine and neutralization-scanning mutagenesis of conserved protonatable residues, we show that cystine binding is coupled to protonation of a clinically relevant aspartate buried in the membrane. Deuterium isotope substitution experiments are consistent with an access of this aspartate from the lysosomal lumen through a deep proton channel. This aspartate lies in one of the two PQ-loop motifs shared by cystinosin with a set of eukaryotic membrane proteins of unknown function and is conserved in about half of them, thus suggesting that other PQ-loop proteins may translocate protons.
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25
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Sandtner W, Egwolf B, Khalili-Araghi F, Sánchez-Rodríguez JE, Roux B, Bezanilla F, Holmgren M. Ouabain binding site in a functioning Na+/K+ ATPase. J Biol Chem 2011; 286:38177-38183. [PMID: 21911500 DOI: 10.1074/jbc.m111.267682] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Na(+)/K(+) ATPase is an almost ubiquitous integral membrane protein within the animal kingdom. It is also the selective target for cardiotonic derivatives, widely prescribed inhibitors for patients with heart failure. Functional studies revealed that ouabain-sensitive residues distributed widely throughout the primary sequence of the protein. Recently, structural work has brought some consensus to the functional observations. Here, we use a spectroscopic approach to estimate distances between a fluorescent ouabain and a lanthanide binding tag (LBT), which was introduced at five different positions in the Na(+)/K(+) ATPase sequence. These five normally functional LBT-Na(+)/K(+) ATPase constructs were expressed in the cell membrane of Xenopus laevis oocytes, operating under physiological internal and external ion conditions. The spectroscopic data suggest two mutually exclusive distances between the LBT and the fluorescent ouabain. From the estimated distances and using homology models of the LBT-Na(+)/K(+) ATPase constructs, approximate ouabain positions could be determined. Our results suggest that ouabain binds at two sites along the ion permeation pathway of the Na(+)/K(+) ATPase. The external site (low apparent affinity) occupies the same region as previous structural findings. The high apparent affinity site is, however, slightly deeper toward the intracellular end of the protein. Interestingly, in both cases the lactone ring faces outward. We propose a sequential ouabain binding mechanism that is consistent with all functional and structural studies.
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Affiliation(s)
- Walter Sandtner
- Department of Pharmacology, Medical University of Vienna, Waehringer Strasse 13A, 1090 Vienna, Austria
| | - Bernhard Egwolf
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Fatemeh Khalili-Araghi
- Department of Biochemistry and Molecular Biology, The University of Chicago Gordon Center for Integrative Science, Chicago, Illinois 60637
| | - Jorge E Sánchez-Rodríguez
- Department of Biochemistry and Molecular Biology, The University of Chicago Gordon Center for Integrative Science, Chicago, Illinois 60637
| | - Benoit Roux
- Department of Biochemistry and Molecular Biology, The University of Chicago Gordon Center for Integrative Science, Chicago, Illinois 60637.
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, The University of Chicago Gordon Center for Integrative Science, Chicago, Illinois 60637.
| | - Miguel Holmgren
- Molecular Neurophysiology Section, Porter Neuroscience Research Center, NINDS, National Institutes of Health, Bethesda, Maryland 20892.
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Stewart AK, Kedar PS, Shmukler BE, Vandorpe DH, Hsu A, Glader B, Rivera A, Brugnara C, Alper SL. Functional characterization and modified rescue of novel AE1 mutation R730C associated with overhydrated cation leak stomatocytosis. Am J Physiol Cell Physiol 2011; 300:C1034-46. [PMID: 21209359 PMCID: PMC3093938 DOI: 10.1152/ajpcell.00447.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 12/23/2010] [Indexed: 01/20/2023]
Abstract
We report the novel, heterozygous AE1 mutation R730C associated with dominant, overhydrated, cation leak stomatocytosis and well-compensated anemia. Parallel elevations of red blood cell cation leak and ouabain-sensitive Na(+) efflux (pump activity) were apparently unaccompanied by increased erythroid cation channel-like activity, and defined ouabain-insensitive Na(+) efflux pathways of nystatin-treated cells were reduced. Epitope-tagged AE1 R730C at the Xenopus laevis oocyte surface exhibited severely reduced Cl(-) transport insensitive to rescue by glycophorin A (GPA) coexpression or by methanethiosulfonate (MTS) treatment. AE1 mutant R730K preserved Cl(-) transport activity, but R730 substitution with I, E, or H inactivated Cl(-) transport. AE1 R730C expression substantially increased endogenous oocyte Na(+)-K(+)-ATPase-mediated (86)Rb(+) influx, but ouabain-insensitive flux was minimally increased and GPA-insensitive. The reduced AE1 R730C-mediated sulfate influx did not exhibit the wild-type pattern of stimulation by acidic extracellular pH (pH(o)) and, unexpectedly, was partially rescued by exposure to sodium 2-sulfonatoethyl methanethiosulfonate (MTSES) but not to 2-aminoethyl methanethiosulfonate hydrobromide (MTSEA) or 2-(trimethylammonium)ethyl methanethiosulfonate bromide (MTSET). AE1 R730E correspondingly exhibited acid pH(o)-stimulated sulfate uptake at rates exceeding those of wild-type AE1 and AE1 R730K, whereas mutants R730I and R730H were inactive and pH(o) insensitive. MTSES-treated oocytes expressing AE1 R730C and untreated oocytes expressing AE1 R730E also exhibited unprecedented stimulation of Cl(-) influx by acid pH(o). Thus recombinant cation-leak stomatocytosis mutant AE1 R730C exhibits severely reduced anion transport unaccompanied by increased Rb(+) and Li(+) influxes. Selective rescue of acid pH(o)-stimulated sulfate uptake and conferral of acid pH(o)-stimulated Cl(-) influx, by AE1 R730E and MTSES-treated R730C, define residue R730 as critical to selectivity and regulation of anion transport by AE1.
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Affiliation(s)
- Andrew K Stewart
- Division of Nephrology, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215, USA
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Bai Y, Li M, Hwang TC. Dual roles of the sixth transmembrane segment of the CFTR chloride channel in gating and permeation. ACTA ACUST UNITED AC 2010; 136:293-309. [PMID: 20805575 PMCID: PMC2931150 DOI: 10.1085/jgp.201010480] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is the only member of the adenosine triphosphate-binding cassette (ABC) transporter superfamily that functions as a chloride channel. Previous work has suggested that the external side of the sixth transmembrane segment (TM6) plays an important role in governing chloride permeation, but the function of the internal side remains relatively obscure. Here, on a cysless background, we performed cysteine-scanning mutagenesis and modification to screen the entire TM6 with intracellularly applied thiol-specific methanethiosulfonate reagents. Single-channel amplitude was reduced in seven cysteine-substituted mutants, suggesting a role of these residues in maintaining the pore structure for normal ion permeation. The reactivity pattern of differently charged reagents suggests that the cytoplasmic part of TM6 assumes a secondary structure of an alpha helix, and that reactive sites (341, 344, 345, 348, 352, and 353) reside in two neighboring faces of the helix. Although, as expected, modification by negatively charged reagents inhibits anion permeation, interestingly, modification by positively charged reagents of cysteine thiolates on one face (344, 348, and 352) of the helix affects gating. For I344C and M348C, the open time was prolonged and the closed time was shortened after modification, suggesting that depositions of positive charges at these positions stabilize the open state but destabilize the closed state. For R352C, which exhibited reduced single-channel amplitude, modifications by two positively charged reagents with different chemical properties completely restored the single-channel amplitude but had distinct effects on both the open time and the closed time. These results corroborate the idea that a helix rotation of TM6, which has been proposed to be part of the molecular motions during transport cycles in other ABC transporters, is associated with gating of the CFTR pore.
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Affiliation(s)
- Yonghong Bai
- Dalton Cardiovascular Research Center, Department of Biological Engineering, University of Missouri-Columbia, Columbia, MO 65211, USA
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Colina C, Palavicini JP, Srikumar D, Holmgren M, Rosenthal JJC. Regulation of Na+/K+ ATPase transport velocity by RNA editing. PLoS Biol 2010; 8:e1000540. [PMID: 21124885 PMCID: PMC2990702 DOI: 10.1371/journal.pbio.1000540] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 10/01/2010] [Indexed: 12/27/2022] Open
Abstract
Editing of Na+/K+ ATPase mRNAs modulates the Na+/K+ pump's turnover rate by selectively targeting the release of the final sodium to the outside. Because firing properties and metabolic rates vary widely, neurons require different transport rates from their Na+/K+ pumps in order to maintain ion homeostasis. In this study we show that Na+/K+ pump activity is tightly regulated by a novel process, RNA editing. Three codons within the squid Na+/K+ ATPase gene can be recoded at the RNA level, and the efficiency of conversion for each varies dramatically, and independently, between tissues. At one site, a highly conserved isoleucine in the seventh transmembrane span can be converted to a valine, a change that shifts the pump's intrinsic voltage dependence. Mechanistically, the removal of a single methyl group specifically targets the process of Na+ release to the extracellular solution, causing a higher turnover rate at the resting membrane potential. In order for excitable cells like neurons and muscles to generate electrical signals, they require ion gradients across their plasma membranes. For example, sodium concentrations are much lower inside a cell than outside, and for potassium it is the opposite case. The job of maintaining these ion gradients falls squarely on a single protein: the Na+/K+ pump. During each transport cycle, this enzyme moves three sodium ions out of the cell and imports two of potassium. Because this process is the foundation for so many physiological processes, the Na+/K+ pump is costly to operate, using ∼30% of the ATP generated by an organism. Proper regulation of its turnover rate is vital. In this work, we use the giant nerve cell of squid as a model to show that the Na+/K+ pump can be regulated by an unsuspected mechanism. Although the gene that codes for this enzyme can make a perfectly functional pump, sometimes its information changes as it passes through the messenger RNA. This is achieved by editing RNA and as a result subtly different versions of the pump can be made, differing at only three amino acids out of more than a thousand. We demonstrate that RNA editing modulates the Na+/K+ pump's turnover rate and sodium release.
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Affiliation(s)
- Claudia Colina
- Institute of Neurobiology, University of Puerto Rico–Medical Sciences Campus, San Juan, Puerto Rico
| | - Juan Pablo Palavicini
- Institute of Neurobiology, University of Puerto Rico–Medical Sciences Campus, San Juan, Puerto Rico
| | - Deepa Srikumar
- Molecular Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Miguel Holmgren
- Molecular Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (MH); (JJCR)
| | - Joshua J. C. Rosenthal
- Institute of Neurobiology, University of Puerto Rico–Medical Sciences Campus, San Juan, Puerto Rico
- Department of Biochemistry, University of Puerto Rico–Medical Sciences Campus, San Juan, Puerto Rico
- * E-mail: (MH); (JJCR)
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Rossini GP, Bigiani A. Palytoxin action on the Na(+),K(+)-ATPase and the disruption of ion equilibria in biological systems. Toxicon 2010; 57:429-39. [PMID: 20932855 DOI: 10.1016/j.toxicon.2010.09.011] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 09/03/2010] [Accepted: 09/24/2010] [Indexed: 11/29/2022]
Abstract
Palytoxin-group toxins (PlTX) exert their potent biological activity by altering mechanisms of ion homeostasis in excitable and non-excitable tissues. This review will describe major aspects that led to the relatively early identification of the Na(+),K(+)-ATPase as the molecular target and receptor of the toxin in sensitive systems. The importance of this pump in the normal functioning of animal cells has driven extensive investigative efforts. The recognized molecular mechanism of action of PlTX involves its binding to the extracellular portion of alpha subunit of this plasma membrane protein, which converts an enzyme carrying ions against their concentration gradients at the expense of chemical energy (ATP) into a non-selective cation channel, allowing passive flow of ions following their concentration gradients. More recent findings have indicated that PlTX would interfere with the normal strict coupling between inner and outer gates of the pump controlling the ion access to the Na(+),K(+)-ATPase, allowing the gates to be simultaneously open. The ability of PlTX to make internal portions of the Na(+),K(+)-ATPase accessible to relatively large molecules has been exploited to characterize the structure-function relationship of the pump, leading to a better understanding of its ion translocation pathway. Thus, forty years from the isolation of this potent marine biotoxin, a considerable understanding of its mode of action and of its potential as a research tool have been achieved and are the basis for promising future advancement in the characterization of biological systems and their alteration by PlTX.
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Affiliation(s)
- Gian Paolo Rossini
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia, Via G. Campi 287, I-41125 Modena, Italy.
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Hoeberichts FA, Perez-Valle J, Montesinos C, Mulet JM, Planes MD, Hueso G, Yenush L, Sharma SC, Serrano R. The role of K+ and H+ transport systems during glucose- and H2O2-induced cell death in Saccharomyces cerevisiae. Yeast 2010; 27:713-25. [DOI: 10.1002/yea.1767] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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31
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In and out of the cation pumps: P-type ATPase structure revisited. Curr Opin Struct Biol 2010; 20:431-9. [PMID: 20634056 DOI: 10.1016/j.sbi.2010.06.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 06/08/2010] [Accepted: 06/15/2010] [Indexed: 12/12/2022]
Abstract
Active transport across membranes is a crucial requirement for life. P-type ATPases build up electrochemical gradients at the expense of ATP by forming and splitting a covalent phosphoenzyme intermediate, coupled to conformational changes in the transmembrane section where the ions are translocated. The marked increment during the last three years in the number of crystal structures of P-type ATPases has greatly improved our understanding of the similarities and differences of pumps with different ion specificities, since the structures of the Ca2+-ATPase, the Na+,K+-ATPase and the H+-ATPase can now be compared directly. Mechanisms for ion gating, charge neutralization and backflow prevention are starting to emerge from comparative structural analysis; and in combination with functional studies of mutated pumps this provides a framework for speculating on how the ions are bound and released as well as on how specificity is achieved.
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Abstract
Marine huge polyol and polyether compounds are remarkable molecules owing to their extraordinary structures and significant biological activities. Currently, palytoxin and maitotoxin are believed to have the longest carbon chains in nature (more than 100 A in length), except for biopolymers. The structural properties of such marine huge molecules are highlighted, especially with regard to the length and shape of their carbon chains.
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Affiliation(s)
- Masaki Kita
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan.
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33
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Accardi A, Picollo A. CLC channels and transporters: proteins with borderline personalities. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1457-64. [PMID: 20188062 DOI: 10.1016/j.bbamem.2010.02.022] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 02/12/2010] [Accepted: 02/18/2010] [Indexed: 11/19/2022]
Abstract
Controlled chloride movement across membranes is essential for a variety of physiological processes ranging from salt homeostasis in the kidneys to acidification of cellular compartments. The CLC family is formed by two, not so distinct, sub-classes of membrane transport proteins: Cl(-) channels and H(+)/Cl(-) exchangers. All CLC's are homodimers with each monomer forming an individual Cl- permeation pathway which appears to be largely unaltered in the two CLC sub-classes. Key residues for ion binding and selectivity are also highly conserved. Most CLC's have large cytosolic carboxy-terminal domains containing two cystathionine beta-synthetase (CBS) domains. The C-termini are critical regulators of protein trafficking and directly modulate Cl- by binding intracellular ATP, H+ or oxidizing compounds. This review focuses on the recent mechanistic insights on the how the structural similarities between CLC channels and transporters translate in unexpected mechanistic analogies between these two sub-classes.
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Affiliation(s)
- Alessio Accardi
- Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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34
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Phycotoxins: chemistry, mechanisms of action and shellfish poisoning. EXPERIENTIA SUPPLEMENTUM 2010; 100:65-122. [PMID: 20358682 DOI: 10.1007/978-3-7643-8338-1_3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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35
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36
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Use of biosensors as alternatives to current regulatory methods for marine biotoxins. SENSORS 2009; 9:9414-43. [PMID: 22291571 PMCID: PMC3260648 DOI: 10.3390/s91109414] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 10/27/2009] [Accepted: 10/28/2009] [Indexed: 12/12/2022]
Abstract
Marine toxins are currently monitored by means of a bioassay that requires the use of many mice, which poses a technical and ethical problem in many countries. With the exception of domoic acid, there is a legal requirement for the presence of other toxins (yessotoxin, saxitoxin and analogs, okadaic acid and analogs, pectenotoxins and azaspiracids) in seafood to be controlled by bioassay, but other toxins, such as palytoxin, cyclic imines, ciguatera and tetrodotoxin are potentially present in European food and there are no legal requirements or technical approaches available to identify their presence. The need for alternative methods to the bioassay is clearly important, and biosensors have become in recent years a feasible alternative to animal sacrifice. This review will discuss the advantages and disadvantages of using biosensors as alternatives to animal assays for marine toxins, with particular focus on surface plasmon resonance (SPR) technology.
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37
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Takeuchi A, Reyes N, Artigas P, Gadsby DC. Visualizing the mapped ion pathway through the Na,K-ATPase pump. Channels (Austin) 2009; 3:383-6. [PMID: 19806033 DOI: 10.4161/chan.3.6.9775] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Na(+),K(+)-ATPase pump achieves thermodynamically uphill exchange of cytoplasmic Na(+) ions for extracellular K(+) ions by using ATP-mediated phosphorylation, followed by autodephosphorylation, to power conformational changes that allow ion access to the pump's binding sites from only one side of the membrane at a time. Formally, the pump behaves like an ion channel with two tightly coupled gates that are constrained to open and close alternately. The marine agent palytoxin disrupts this coupling, allowing both gates to sometimes be open, so temporarily transforming a pump into an ion channel. We made a cysteine scan of Na(+),K(+)-ATPase transmembrane (TM) segments TM1 to TM6, and used recordings of Na(+) current flow through palytoxin-bound pump-channels to monitor accessibility of introduced cysteine residues via their reaction with hydrophilic methanethiosulfonate (MTS) reagents. To visualize the open-channel pathway, the reactive positions were mapped onto a homology model of Na(+),K(+)-ATPase based on the structure of the related sarcoplasmicand endoplasmic-reticulum (SERCA) Ca(2+)-ATPase in a BeF(3)(-)-trapped state,(1,2) in which the extra-cytoplasmic gate is wide open (although the cytoplasmic access pathway is firmly shut). The results revealed a single unbroken chain of reactive positions that traverses the pump from the extracellular surface to the cytoplasm, comprises residues from TM1, TM2, TM4 and TM6, and passes through the equivalent of cation binding site II in SERCA, but not through site I. Cavity search analysis of the homology model validated its use for mapping the data by yielding a calculated extra-cytoplasmic pathway surrounded by MTS-reactive residues. As predicted by previous experimental results, that calculated extra-cytoplasmic pathway abruptly broadens above residue T806, at the outermost end of TM6 that forms the floor of the extracellular-facing vestibule. These findings provide a structural basis for further understanding cation translocation by the Na(+),K(+)-ATPase and by other P-type pumps like the Ca(2+)- and H(+),K(+)-ATPases.
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Affiliation(s)
- Ayako Takeuchi
- Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, NY, USA
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38
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Rinaldi DE, Adamo HP. The role of the Ca2+ binding ligand Asn879 in the function of the plasma membrane Ca2+ pump. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2404-10. [PMID: 19761757 DOI: 10.1016/j.bbamem.2009.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 08/26/2009] [Accepted: 09/06/2009] [Indexed: 11/27/2022]
Abstract
Asn879 in the transmembrane segment M6 of the plasma membrane Ca(2+) pump (PMCA human isoform 4xb) has been proposed to coordinate Ca(2+) at the transport site through its carboxylate. This idea agrees with the fact that this Asn is conserved in other Ca(2+)-ATPases but is replaced by Asp, Glu, and other residues in closely related 2P-type ATPases of different ionic specificity. Previous mutagenesis studies have shown that the substitution of Ala for Asn abolishes the activity of the enzyme (Adebayo et al., 1995; Guerini et al., 1996). We have constructed a mutant PMCA in which the Asn879 was substituted by Asp. The mutant protein was expressed in Saccharomyces cerevisiae, solubilized and purified by calmodulin affinity chromatography. The Asn879Asp PMCA mutant exhibited about 30% of the wild type Ca(2+)-dependent ATPase activity and only a minor reduction of the apparent affinity for Ca(2+). The decrease in the Ca(2+)-ATPase of the mutant enzyme was in parallel with the reduction in the amount of phosphoenzyme formed from Ca(2+) plus ATP. Noteworthy, the mutation nearly eliminated the ability of the enzyme to hydrolyze pNPP which is maximal in the absence of Ca(2+) revealing a major effect of the mutation on the Ca(2+)-independent reactions of the transport cycle. At a pH low enough to protonate the Asp carboxylate the pNPPase activity of Asn879Asp increased, suggesting that the binding of protons to Asn879 is essential for the activities catalyzed by E(2)-like forms of the enzyme.
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Affiliation(s)
- Débora E Rinaldi
- Instituto de Química y Fisicoquímica Biológicas (IQUIFIB)-Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Ciudad de Buenos Aires, Argentina
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39
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Teriete P, Thai K, Choi J, Marassi FM. Effects of PKA phosphorylation on the conformation of the Na,K-ATPase regulatory protein FXYD1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2462-70. [PMID: 19761758 DOI: 10.1016/j.bbamem.2009.09.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 08/21/2009] [Accepted: 09/06/2009] [Indexed: 12/17/2022]
Abstract
FXYD1 (phospholemman) is a member of an evolutionarily conserved family of membrane proteins that regulate the function of the Na,K-ATPase enzyme complex in specific tissues and specific physiological states. In heart and skeletal muscle sarcolemma, FXYD1 is also the principal substrate of hormone-regulated phosphorylation by c-AMP dependent protein kinase A and by protein kinase C, which phosphorylate the protein at conserved Ser residues in its cytoplasmic domain, altering its Na,K-ATPase regulatory activity. FXYD1 adopts an L-shaped alpha-helical structure with the transmembrane helix loosely connected to a cytoplasmic amphipathic helix that rests on the membrane surface. In this paper we describe NMR experiments showing that neither PKA phosphorylation at Ser68 nor the physiologically relevant phosphorylation mimicking mutation Ser68Asp induces major changes in the protein conformation. The results, viewed in light of a model of FXYD1 associated with the Na,K-ATPase alpha and beta subunits, indicate that the effects of phosphorylation on the Na,K-ATPase regulatory activity of FXYD1 could be due primarily to changes in electrostatic potential near the membrane surface and near the Na(+)/K(+) ion binding site of the Na,K-ATPase alpha subunit.
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Affiliation(s)
- Peter Teriete
- Burnham Institute for Medical Research, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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40
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Ion transport and energy transduction of P-type ATPases: Implications from electrostatic calculations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:721-9. [DOI: 10.1016/j.bbabio.2009.02.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 02/13/2009] [Accepted: 02/17/2009] [Indexed: 12/12/2022]
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41
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Voltage clamp fluorometry: Combining fluorescence and electrophysiological methods to examine the structure–function of the Na+/K+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:714-20. [DOI: 10.1016/j.bbabio.2009.03.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/29/2009] [Accepted: 03/30/2009] [Indexed: 11/23/2022]
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42
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Ares IR, Cagide E, Louzao MC, Espiña B, Vieytes MR, Yasumoto T, Botana LM. Ostreocin-D impact on globular actin of intact cells. Chem Res Toxicol 2009; 22:374-81. [PMID: 19154108 DOI: 10.1021/tx800273f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ostreocin-D, discovered in the past decade, is a marine toxin produced by dinoflagellates. It shares structure with palytoxin, a toxic compound responsible for the seafood intoxication named clupeotoxism. At the cellular level, the action sites and pharmacological effects for ostreocin-D are still almost unknown. Previously, we demonstrated that these toxins change the filamentous actin cytoskeleton, which is essential for multiple cellular functions. However, nothing has yet been reported about what happens with the unpolymerized actin pool. Here (i) the effects induced by ostreocin-D on unpolymerized actin, (ii) the Ca2+ role in such a process, and (iii) the cytotoxic activity of ostreocin-D on the human neuroblastoma BE(2)-M17 cell line are shown for the first time. Fluorescently labeled DNase I was used for staining of monomeric actin prior to detection with both laser-scanning cytometry and confocal microscopy techniques. Cellular viability was tested through a microplate metabolic activity assay. Ostreocin-D elicited a rearrangement of monomeric actin toward the nuclear region. This event was not accompanied by changes in its content. In addition, the presence or absence of external Ca2+ did not change these results. This toxin was also found to cause a decrease in the viability of neuroblastoma cells, which was inhibited by the specific blocker of Na+/K+-ATPase, ouabain. All these responses were comparable to those obtained with palytoxin under identical conditions. The data suggest that ostreocin-D modulates the unassembled actin pool, activating signal transduction pathways not related to Ca2+ influx in the same way as palytoxin.
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Affiliation(s)
- Isabel R Ares
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo, Spain
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Gadsby DC. Ion channels versus ion pumps: the principal difference, in principle. Nat Rev Mol Cell Biol 2009; 10:344-52. [PMID: 19339978 DOI: 10.1038/nrm2668] [Citation(s) in RCA: 302] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The incessant traffic of ions across cell membranes is controlled by two kinds of border guards: ion channels and ion pumps. Open channels let selected ions diffuse rapidly down electrical and concentration gradients, whereas ion pumps labour tirelessly to maintain the gradients by consuming energy to slowly move ions thermodynamically uphill. Because of the diametrically opposed tasks and the divergent speeds of channels and pumps, they have traditionally been viewed as completely different entities, as alike as chalk and cheese. But new structural and mechanistic information about both of these classes of molecular machines challenges this comfortable separation and forces its re-evaluation.
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Affiliation(s)
- David C Gadsby
- Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, 1230 York Avenue, New York, New York 10065-6399, USA.
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44
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Gadsby DC, Takeuchi A, Artigas P, Reyes N. Review. Peering into an ATPase ion pump with single-channel recordings. Philos Trans R Soc Lond B Biol Sci 2009; 364:229-38. [PMID: 18986966 DOI: 10.1098/rstb.2008.0243] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In principle, an ion channel needs no more than a single gate, but a pump requires at least two gates that open and close alternately to allow ion access from only one side of the membrane at a time. In the Na+,K+-ATPase pump, this alternating gating effects outward transport of three Na+ ions and inward transport of two K+ ions, for each ATP hydrolysed, up to a hundred times per second, generating a measurable current if assayed in millions of pumps. Under these assay conditions, voltage jumps elicit brief charge movements, consistent with displacement of ions along the ion pathway while one gate is open but the other closed. Binding of the marine toxin, palytoxin, to the Na+,K+-ATPase uncouples the two gates, so that although each gate still responds to its physiological ligand they are no longer constrained to open and close alternately, and the Na+,K+-ATPase is transformed into a gated cation channel. Millions of Na+ or K+ ions per second flow through such an open pump-channel, permitting assay of single molecules and allowing unprecedented access to the ion transport pathway through the Na+,K+-ATPase. Use of variously charged small hydrophilic thiol-specific reagents to probe cysteine targets introduced throughout the pump's transmembrane segments allows mapping and characterization of the route traversed by transported ions.
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Affiliation(s)
- David C Gadsby
- Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, NY 10065, USA.
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45
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Investigating the potassium interactions with the palytoxin induced channels in Na+/K+ pump. Comput Biol Chem 2009; 33:14-21. [DOI: 10.1016/j.compbiolchem.2008.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 07/03/2008] [Accepted: 07/06/2008] [Indexed: 11/18/2022]
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Takeuchi A, Reyes N, Artigas P, Gadsby DC. The ion pathway through the opened Na(+),K(+)-ATPase pump. Nature 2008; 456:413-6. [PMID: 18849964 PMCID: PMC2585603 DOI: 10.1038/nature07350] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Accepted: 08/20/2008] [Indexed: 11/09/2022]
Abstract
P-type ATPases pump ions across membranes, generating steep electrochemical gradients that are essential for the function of all cells. Access to the ion-binding sites within the pumps alternates between the two sides of the membrane to avoid the dissipation of the gradients that would occur during simultaneous access. In Na(+),K(+)-ATPase pumps treated with the marine agent palytoxin, this strict alternation is disrupted and binding sites are sometimes simultaneously accessible from both sides of the membrane, transforming the pumps into ion channels (see, for example, refs 2, 3). Current recordings in these channels can monitor accessibility of introduced cysteine residues to water-soluble sulphydryl-specific reagents. We found previously that Na(+),K(+) pump-channels open to the extracellular surface through a deep and wide vestibule that emanates from a narrower pathway between transmembrane helices 4 and 6 (TM4 and TM6). Here we report that cysteine scans from TM1 to TM6 reveal a single unbroken cation pathway that traverses palytoxin-bound Na(+),K(+) pump-channels from one side of the membrane to the other. This pathway comprises residues from TM1, TM2, TM4 and TM6, passes through ion-binding site II, and is probably conserved in structurally and evolutionarily related P-type pumps, such as sarcoplasmic- and endoplasmic-reticulum Ca(2+)-ATPases and H(+),K(+)-ATPases.
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Affiliation(s)
- Ayako Takeuchi
- Laboratory of Cardiac/Membrane Physiology, The Rockefeller University, New York, New York 10065, USA
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The twain shall meet: channels, transporters and things between. Meeting on Membrane Transport in Flux: the Ambiguous Interface Between Channels and Pumps. EMBO Rep 2008; 9:960-5. [PMID: 18772896 DOI: 10.1038/embor.2008.172] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Accepted: 08/11/2008] [Indexed: 11/09/2022] Open
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Sodium Gill Potential as a Tool to Monitor Valve Closure Behavior in Freshwater Clam Corbicula fluminea in Response to Copper. SENSORS 2008; 8:5250-5269. [PMID: 27873813 PMCID: PMC3705503 DOI: 10.3390/s8095250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 08/14/2008] [Accepted: 08/28/2008] [Indexed: 11/17/2022]
Abstract
Valve closure behavior in freshwater clam Corbicula fluminea is a biologically sensitive endpoint. The purpose of this paper was to derive an electrophysiological response model of C. fluminea to assess copper (Cu)–sodium (Na) interactions in gill membrane, whereby valve closure behavior and Cu toxicity could be monitored. The proposed model was based on the integration of Cu bioavailability, Na and Cu internalizations, and electrochemically-based gill potentials. Based on Na active transport under non-equilibrium conditions, predicted gill potential of −8.2 mV agreed reasonably well with published the measured transepithelial potential of −7 mV in C. fluminea. Our proposed framework captured the general features observed in model applications including: (i) 50% inhibitory Cu2+ activities for Na membrane potential (ENa) and uptake rate (JNa) were estimated to be 0.072 and 0.043 μM, respectively, with a stoichiometry of 3Cu2+: 1ENa and 1JNa; (ii) the external Cu2+–dependent internal Na concentration could be parsimoniously estimated, and (iii) the site-specific clam gill potentials could be monitored. Here we provided a new approach to monitor waterborne metal toxicity to reduce the nationwide economic losses due to bans on harvesting of contaminated clam and the potential risks to the health of clams.
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Ion permeation through a Cl--selective channel designed from a CLC Cl-/H+ exchanger. Proc Natl Acad Sci U S A 2008; 105:11194-9. [PMID: 18678918 DOI: 10.1073/pnas.0804503105] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The CLC family of Cl(-)-transporting proteins includes both Cl(-) channels and Cl(-)/H(+) exchange transporters. CLC-ec1, a structurally known bacterial homolog of the transporter subclass, exchanges two Cl(-) ions per proton with strict, obligatory stoichiometry. Point mutations at two residues, Glu(148) and Tyr(445), are known to impair H(+) movement while preserving Cl(-) transport. In the x-ray crystal structure of CLC-ec1, these residues form putative "gates" flanking an ion-binding region. In mutants with both of the gate-forming side chains reduced in size, H(+) transport is abolished, and unitary Cl(-) transport rates are greatly increased, well above values expected for transporter mechanisms. Cl(-) transport rates increase as side-chain volume at these positions is decreased. The crystal structure of a doubly ungated mutant shows a narrow conduit traversing the entire protein transmembrane width. These characteristics suggest that Cl(-) flux through uncoupled, ungated CLC-ec1 occurs via a channel-like electrodiffusion mechanism rather than an alternating-exposure conformational cycle that has been rendered proton-independent by the gate mutations.
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Inuzuka T, Uemura D, Arimoto H. The conformational features of palytoxin in aqueous solution. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.06.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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