1
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Boyer JC, Véry AA, Fristot E, Guyot V, Sentenac H, Peltier JB. Cell-free expressed uniporter and symporter systems from the plant HKT transporter family display channel-like gating and unitary conductances. THE NEW PHYTOLOGIST 2024. [PMID: 38992953 DOI: 10.1111/nph.19958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 06/24/2024] [Indexed: 07/13/2024]
Affiliation(s)
- Jean-Christophe Boyer
- IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, CEDEX 2, Montpellier, 34060, France
| | - Anne-Aliénor Véry
- IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, CEDEX 2, Montpellier, 34060, France
| | - Elsa Fristot
- IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, CEDEX 2, Montpellier, 34060, France
| | - Valentin Guyot
- IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, CEDEX 2, Montpellier, 34060, France
| | - Hervé Sentenac
- IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, CEDEX 2, Montpellier, 34060, France
| | - Jean-Benoît Peltier
- IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, CEDEX 2, Montpellier, 34060, France
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2
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Tichy J, Waldherr M, Ortbauer M, Graf A, Sipek B, Jembrih-Simbuerger D, Sterflinger K, Piñar G. Pretty in pink? Complementary strategies for analysing pink biofilms on historical buildings. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166737. [PMID: 37659529 DOI: 10.1016/j.scitotenv.2023.166737] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/21/2023] [Accepted: 08/30/2023] [Indexed: 09/04/2023]
Abstract
Salt-weathering is a deterioration mechanism affecting building materials that results from repetitive cycles of salt crystallisation-dissolution in the porous mineral network under changing environmental conditions, causing damage to surfaces. However, an additional biodeterioration phenomenon frequently associated with salt efflorescence is the appearance of coloured biofilms, comprising halotolerant/halophilic microorganisms, containing carotenoid pigments that cause pinkish patinas. In this work, two Austrian historical salt-weathered buildings showing pink biofilms, the St. Virgil's Chapel and the Charterhouse Mauerbach, were investigated. Substrate chemistry (salt concentration/composition) was analysed by ion chromatography and X-ray diffraction to correlate these parameters with the associated microorganisms. Microbiomes were analysed by sequencing full-length 16S rRNA amplicons using Nanopore technology. Data demonstrates that microbiomes are not only influenced by salt concentration, but also by its chemical composition. The chapel showed a high overall halite (NaCl) concentration, but the factor influencing the microbiome was the presence/absence of K+. The K+ areas showed a dominance of Aliifodinibius and Salinisphaera species, capable of tolerating high salt concentrations through the "salt-in" strategy by transporting K+ into cells. Conversely, areas without K+ showed a community shift towards Halomonas species, which favour the synthesis of compatible solutes for salt tolerance. In the charterhouse, the main salts were sulphates. In areas with low concentrations, Rubrobacter species dominated, while in areas with high concentrations, Haloechinothrix species did. Among archaea, Haloccoccus species were dominant in all samples, except at high sulphate concentrations, where Halalkalicoccus prevailed. Finally, the biological pigments visible in both buildings were analysed by Raman spectroscopy, showing the same spectra in all areas investigated, regardless of the building and the microbiomes, demonstrating the presence of carotenoids in the pink biofilms. Comprehensive information on the factors affecting the microbiome associated with salt-weathered buildings should provide the basis for selecting the most appropriate desalination treatment to remove both salt efflorescence and associated biofilms.
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Affiliation(s)
- Johannes Tichy
- Institute for Natural Sciences and Technology in the Art, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria.
| | - Monika Waldherr
- Department of Applied Life Sciences/Bioengineering/Bioinformatics, FH Campus Wien, Favoritenstrasse 226, A-1100 Vienna, Austria
| | - Martin Ortbauer
- Institute for Conservation - Restoration, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria
| | - Alexandra Graf
- Department of Applied Life Sciences/Bioengineering/Bioinformatics, FH Campus Wien, Favoritenstrasse 226, A-1100 Vienna, Austria
| | - Beate Sipek
- Institute for Conservation - Restoration, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria
| | - Dubravka Jembrih-Simbuerger
- Institute for Natural Sciences and Technology in the Art, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria
| | - Katja Sterflinger
- Institute for Natural Sciences and Technology in the Art, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria
| | - Guadalupe Piñar
- Institute for Natural Sciences and Technology in the Art, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria
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3
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Gu S, Han S, Abid M, Bai D, Lin M, Sun L, Qi X, Zhong Y, Fang J. A High-K + Affinity Transporter (HKT) from Actinidia valvata Is Involved in Salt Tolerance in Kiwifruit. Int J Mol Sci 2023; 24:15737. [PMID: 37958739 PMCID: PMC10647804 DOI: 10.3390/ijms242115737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Ion transport is crucial for salt tolerance in plants. Under salt stress, the high-affinity K+ transporter (HKT) family is mainly responsible for the long-distance transport of salt ions which help to reduce the deleterious effects of high concentrations of ions accumulated within plants. Kiwifruit is well known for its susceptibility to salt stress. Therefore, a current study was designed to decipher the molecular regulatory role of kiwifruit HKT members in the face of salt stress. The transcriptome data from Actinidia valvata revealed that salt stress significantly induced the expression of AvHKT1. A multiple sequence alignment analysis indicated that the AvHKT1 protein contains three conserved amino acid sites for the HKT family. According to subcellular localization analysis, the protein was primarily present in the cell membrane and nucleus. Additionally, we tested the AvHKT1 overexpression in 'Hongyang' kiwifruit, and the results showed that the transgenic lines exhibited less leaf damage and improved plant growth compared to the control plants. The transgenic lines displayed significantly higher SPAD and Fv/Fm values than the control plants. The MDA contents of transgenic lines were also lower than that of the control plants. Furthermore, the transgenic lines accumulated lower Na+ and K+ contents, proving this protein involvement in the transport of Na+ and K+ and classification as a type II HKT transporter. Further research showed that the peroxidase (POD) activity in the transgenic lines was significantly higher, indicating that the salt-induced overexpression of AvHKT1 also scavenged POD. The promoter of AvHKT1 contained phytohormone and abiotic stress-responsive cis-elements. In a nutshell, AvHKT1 improved kiwifruit tolerance to salinity by facilitating ion transport under salt stress conditions.
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Affiliation(s)
| | | | | | | | | | | | | | - Yunpeng Zhong
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou 450009, China; (S.G.); (S.H.); (M.A.); (D.B.); (M.L.); (L.S.); (X.Q.)
| | - Jinbao Fang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou 450009, China; (S.G.); (S.H.); (M.A.); (D.B.); (M.L.); (L.S.); (X.Q.)
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4
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Tanudjaja E, Hoshi N, Yamamoto K, Ihara K, Furuta T, Tsujii M, Ishimaru Y, Uozumi N. Two Trk/Ktr/HKT-type potassium transporters, TrkG and TrkH, perform distinct functions in Escherichia coli K-12. J Biol Chem 2022; 299:102846. [PMID: 36586436 PMCID: PMC9898762 DOI: 10.1016/j.jbc.2022.102846] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
Escherichia coli K-12 possesses two versions of Trk/Ktr/HKT-type potassium ion (K+) transporters, TrkG and TrkH. The current paradigm is that TrkG and TrkH have largely identical characteristics, and little information is available regarding their functional differences. Here, we show using cation uptake experiments with K+ transporter knockout mutants that TrkG and TrkH have distinct ion transport activities and physiological roles. K+-transport by TrkG required Na+, whereas TrkH-mediated K+ uptake was not affected by Na+. An aspartic acid located five residues away from a critical glycine in the third pore-forming region might be involved in regulation of Na+-dependent activation of TrkG. In addition, we found that TrkG but not TrkH had Na+ uptake activity. Our analysis of K+ transport mutants revealed that TrkH supported cell growth more than TrkG; however, TrkG was able to complement loss of TrkH-mediated K+ uptake in E. coli. Furthermore, we determined that transcription of trkG in E. coli was downregulated but not completely silenced by the xenogeneic silencing factor H-NS (histone-like nucleoid structuring protein or heat-stable nucleoid-structuring protein). Taken together, the transport function of TrkG is clearly distinct from that of TrkH, and TrkG seems to have been accepted by E. coli during evolution as a K+ uptake system that coexists with TrkH.
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Affiliation(s)
- Ellen Tanudjaja
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Naomi Hoshi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | | | - Kunio Ihara
- Center for Gene Research, Nagoya University, Nagoya, Japan
| | - Tadaomi Furuta
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Masaru Tsujii
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Yasuhiro Ishimaru
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan.
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5
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Kulik N, Kale D, Spurna K, Shamayeva K, Hauser F, Milic S, Janout H, Zayats V, Jacak J, Ludwig J. Dimerisation of the Yeast K + Translocation Protein Trk1 Depends on the K + Concentration. Int J Mol Sci 2022; 24:ijms24010398. [PMID: 36613841 PMCID: PMC9820094 DOI: 10.3390/ijms24010398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/16/2022] [Accepted: 12/21/2022] [Indexed: 12/28/2022] Open
Abstract
In baker's yeast (Saccharomyces cerevisiae), Trk1, a member of the superfamily of K-transporters (SKT), is the main K+ uptake system under conditions when its concentration in the environment is low. Structurally, Trk1 is made up of four domains, each similar and homologous to a K-channel α subunit. Because most K-channels are proteins containing four channel-building α subunits, Trk1 could be functional as a monomer. However, related SKT proteins TrkH and KtrB were crystallised as dimers, and for Trk1, a tetrameric arrangement has been proposed based on molecular modelling. Here, based on Bimolecular Fluorescence Complementation experiments and single-molecule fluorescence microscopy combined with molecular modelling; we provide evidence that Trk1 can exist in the yeast plasma membrane as a monomer as well as a dimer. The association of monomers to dimers is regulated by the K+ concentration.
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Affiliation(s)
- Natalia Kulik
- Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 3733 Nove Hrady, Czech Republic
| | - Deepika Kale
- Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 3733 Nove Hrady, Czech Republic
| | - Karin Spurna
- Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 3733 Nove Hrady, Czech Republic
| | - Katsiaryna Shamayeva
- Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 3733 Nove Hrady, Czech Republic
| | - Fabian Hauser
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstr, 21, 4020 Linz, Austria
| | - Sandra Milic
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstr, 21, 4020 Linz, Austria
| | - Hannah Janout
- Bioinformatics, University of Applied Sciences Upper Austria, 4232 Hagenberg, Austria
- Institute of Symbolic AI, Johannes Kepler University, 4040 Linz, Austria
| | - Vasilina Zayats
- Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 3733 Nove Hrady, Czech Republic
| | - Jaroslaw Jacak
- School of Medical Engineering and Applied Social Sciences, University of Applied Sciences Upper Austria, Garnisonstr, 21, 4020 Linz, Austria
| | - Jost Ludwig
- Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 3733 Nove Hrady, Czech Republic
- Correspondence:
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6
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Blair JMA, Zeth K, Bavro VN, Sancho-Vaello E. The role of bacterial transport systems in the removal of host antimicrobial peptides in Gram-negative bacteria. FEMS Microbiol Rev 2022; 46:6617596. [PMID: 35749576 PMCID: PMC9629497 DOI: 10.1093/femsre/fuac032] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/23/2022] [Accepted: 06/22/2022] [Indexed: 01/09/2023] Open
Abstract
Antibiotic resistance is a global issue that threatens our progress in healthcare and life expectancy. In recent years, antimicrobial peptides (AMPs) have been considered as promising alternatives to the classic antibiotics. AMPs are potentially superior due to their lower rate of resistance development, since they primarily target the bacterial membrane ('Achilles' heel' of the bacteria). However, bacteria have developed mechanisms of AMP resistance, including the removal of AMPs to the extracellular space by efflux pumps such as the MtrCDE or AcrAB-TolC systems, and the internalization of AMPs to the cytoplasm by the Sap transporter, followed by proteolytic digestion. In this review, we focus on AMP transport as a resistance mechanism compiling all the experimental evidence for the involvement of efflux in AMP resistance in Gram-negative bacteria and combine this information with the analysis of the structures of the efflux systems involved. Finally, we expose some open questions with the aim of arousing the interest of the scientific community towards the AMPs-efflux pumps interactions. All the collected information broadens our understanding of AMP removal by efflux pumps and gives some clues to assist the rational design of AMP-derivatives as inhibitors of the efflux pumps.
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Affiliation(s)
- Jessica M A Blair
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Kornelius Zeth
- Department of Science and Environment, Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
| | - Vassiliy N Bavro
- School of Life Sciences, University of Essex, Colchester, CO4 3SQ, United Kingdom
| | - Enea Sancho-Vaello
- Corresponding author. College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom. E-mail:
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7
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Imran S, Oyama M, Horie R, Kobayashi NI, Costa A, Kumano R, Hirata C, Tran STH, Katsuhara M, Tanoi K, Kohchi T, Ishizaki K, Horie T. Distinct Functions of the Atypical Terminal Hydrophilic Domain of the HKT Transporter in the Liverwort Marchantia polymorpha. PLANT & CELL PHYSIOLOGY 2022; 63:802-816. [PMID: 35380735 DOI: 10.1093/pcp/pcac044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/29/2022] [Accepted: 04/03/2022] [Indexed: 06/14/2023]
Abstract
K+/Na+ homeostasis is important for land plants, particularly under salt stress. In this study, the structure and ion transport properties of the high-affinity K+ transporter (HKT) of the liverwort Marchantia polymorpha were investigated. Only one HKT gene, MpHKT1, was identified in the genome of M. polymorpha. Phylogenetic analysis of HKT proteins revealed that non-seed plants possess HKTs grouped into a clade independent of the other two clades including HKTs of angiosperms. A distinct long hydrophilic domain was found in the C-terminus of MpHKT1. Complementary DNA (cDNA) of truncated MpHKT1 (t-MpHKT1) encoding the MpHKT_Δ596-812 protein was used to examine the functions of the C-terminal domain. Both MpHKT1 transporters fused with enhanced green fluorescent protein at the N-terminus were localized to the plasma membrane when expressed in rice protoplasts. Two-electrode voltage clamp experiments using Xenopus laevis oocytes indicated that MpHKT1 mediated the transport of monovalent alkali cations with higher selectivity for Na+ and K+, but truncation of the C-terminal domain significantly reduced the transport activity with a decrease in the Na+ permeability. Overexpression of MpHKT1 or t-MpHKT1 in M. polymorpha conferred accumulation of higher Na+ levels and showed higher Na+ uptake rates, compared to those of wild-type plants; however, phenotypes with t-MpHKT1 were consistently weaker than those with MpHKT1. Together, these findings suggest that the hydrophilic C-terminal domain plays a unique role in the regulation of transport activity and ion selectivity of MpHKT1.
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Affiliation(s)
- Shahin Imran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046 Japan
- Department of Agronomy, Khulna Agricultural University, Khulna 9100, Bangladesh
| | - Masumi Oyama
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
| | - Rie Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
| | - Natsuko I Kobayashi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan
| | - Alex Costa
- Department of Biosciences, University of Milan, Via Celoria 26, Milano 20133, Italy
- Institute of Biophysics, National Research Council of Italy (CNR), Milano 20133, Italy
| | - Ryosuke Kumano
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
| | - Chiho Hirata
- Graduate School of Science, Kobe University, Kobe, Hyogo 657-8501 Japan
| | - Sen Thi Huong Tran
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046 Japan
- Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Hue, Thua Thien Hue 530000, Vietnam
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama 710-0046 Japan
| | - Keitaro Tanoi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8502 Japan
| | | | - Tomoaki Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano, 386-8567 Japan
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8
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Jiang W, Jin R, Wang D, Yang Y, Zhao P, Liu M, Zhang A, Tang Z. A Novel High-Affinity Potassium Transporter IbHKT-like Gene Enhances Low-Potassium Tolerance in Transgenic Roots of Sweet Potato ( Ipomoea batatas (L.) Lam.). PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11111389. [PMID: 35684162 PMCID: PMC9182616 DOI: 10.3390/plants11111389] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/13/2022] [Accepted: 05/17/2022] [Indexed: 05/27/2023]
Abstract
The high-affinity potassium transporters (HKT) mediate K+-Na+ homeostasis in plants. However, the function of enhancing low-potassium tolerance in sweet potato [Ipomoea batatas (L.) Lam.] remains unrevealed. In this study, a novel HKT transporter homolog IbHKT-like gene was cloned from sweet potato, which was significantly induced by potassium deficiency stress. IbHKT-like overexpressing transgenic roots were obtained from a sweet potato cultivar Xuzishu8 using an Agrobacterium rhizogenes-mediated root transgenic system in vivo. Compared with the CK, whose root cells did not overexpress the IbHKT-like gene, overexpression of the IbHKT-like gene protected cell ultrastructure from damage, and transgenic root meristem cells had intact mitochondria, endoplasmic reticulum, and Golgi dictyosomes. The steady-state K+ influx increased by 2.2 times in transgenic root meristem cells. Overexpression of the IbHKT-like gene also improved potassium content in the whole plant, which increased by 63.8% compared with the CK plants. These results could imply that the IbHKT-like gene, as a high-affinity potassium transporter gene, may play an important role in potassium deficiency stress responses.
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Affiliation(s)
- Wei Jiang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
| | - Rong Jin
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
| | - Danfeng Wang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
| | - Yufeng Yang
- Cereal Research Institute, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China;
| | - Peng Zhao
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
| | - Ming Liu
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
| | - Aijun Zhang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
| | - Zhonghou Tang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Xuzhou 221121, China; (W.J.); (R.J.); (D.W.); (P.Z.); (M.L.); (A.Z.)
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9
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Ruiz-Castilla FJ, Ruiz Pérez FS, Ramos-Moreno L, Ramos J. Candida albicans Potassium Transporters. Int J Mol Sci 2022; 23:ijms23094884. [PMID: 35563275 PMCID: PMC9105532 DOI: 10.3390/ijms23094884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/26/2022] [Accepted: 04/26/2022] [Indexed: 12/10/2022] Open
Abstract
Potassium is basic for life. All living organisms require high amounts of intracellular potassium, which fulfils multiple functions. To reach efficient potassium homeostasis, eukaryotic cells have developed a complex and tightly regulated system of transporters present both in the plasma membrane and in the membranes of internal organelles that allow correct intracellular potassium content and distribution. We review the information available on the pathogenic yeast Candida albicans. While some of the plasma membrane potassium transporters are relatively well known and experimental data about their nature, function or regulation have been published, in the case of most of the transporters present in intracellular membranes, their existence and even function have just been deduced because of their homology with those present in other yeasts, such as Saccharomyces cerevisiae. Finally, we analyse the possible links between pathogenicity and potassium homeostasis. We comment on the possibility of using some of these transporters as tentative targets in the search for new antifungal drugs.
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10
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Yeast Trk1 Potassium Transporter Gradually Changes Its Affinity in Response to Both External and Internal Signals. J Fungi (Basel) 2022; 8:jof8050432. [PMID: 35628688 PMCID: PMC9144525 DOI: 10.3390/jof8050432] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/14/2022] [Accepted: 04/20/2022] [Indexed: 01/04/2023] Open
Abstract
Yeasts need a high intracellular concentration of potassium to grow. The main K+ uptake system in Saccharomyces cerevisiae is the Trk1 transporter, a complex protein with four MPM helical membrane motifs. Trk1 has been shown to exist in low- or high-affinity modes, which reflect the availability of potassium in the environment. However, when and how the affinity changes, and whether the potassium availability is the only signal for the affinity switch, remains unknown. Here, we characterize the Trk1 kinetic parameters under various conditions and find that Trk1’s KT and Vmax change gradually. This gliding adjustment is rapid and precisely reflects the changes in the intracellular potassium content and membrane potential. A detailed characterization of the specific mutations in the P-helices of the MPM segments reveals that the presence of proline in the P-helix of the second and third MPM domain (F820P and L949P) does not affect the function of Trk1 in general, but rather specifically prevents the transporter’s transition to a high-affinity state. The analogous mutations in the two remaining MPM domains (L81P and L1115P) result in a mislocalized and inactive protein, highlighting the importance of the first and fourth P-helices in proper Trk1 folding and activity at the plasma membrane.
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11
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Dave A, Agarwal P, Agarwal PK. Mechanism of high affinity potassium transporter (HKT) towards improved crop productivity in saline agricultural lands. 3 Biotech 2022; 12:51. [PMID: 35127306 PMCID: PMC8795266 DOI: 10.1007/s13205-021-03092-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 12/10/2021] [Indexed: 02/03/2023] Open
Abstract
Glycophytic plants are susceptible to salinity and their growth is hampered in more than 40 mM of salt. Salinity not only affects crop yield but also limits available land for farming by decreasing its fertility. Presence of distinct traits in response to environmental conditions might result in evolutionary adaptations. A better understanding of salinity tolerance through a comprehensive study of how Na+ is transported will help in the development of plants with improved salinity tolerance and might lead to increased yield of crops growing in strenuous environment. Ion transporters play pivotal role in salt homeostasis and maintain low cytotoxic effect in the cell. High-affinity potassium transporters are the critical class of integral membrane proteins found in plants. It mainly functions to remove excess Na+ from the transpiration stream to prevent sodium toxicity in the salt-sensitive shoot and leaf tissues. However, there are large number of HKT proteins expressed in plants, and it is possible that these members perform in a wide range of functions. Understanding their mechanism and functions will aid in further manipulation and genetic transformation of different crops. This review focuses on current knowledge of ion selectivity and molecular mechanisms controlling HKT gene expression. The current review highlights the mechanism of different HKT transporters from different plant sources and how this knowledge could prove as a valuable tool to improve crop productivity.
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Affiliation(s)
- Ankita Dave
- Plant Omics Division, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Bhavnagar, Gujarat 364 002 India ,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
| | - Parinita Agarwal
- Plant Omics Division, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Bhavnagar, Gujarat 364 002 India
| | - Pradeep K. Agarwal
- Plant Omics Division, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Bhavnagar, Gujarat 364 002 India ,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India
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12
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Andrew RD, Hartings JA, Ayata C, Brennan KC, Dawson-Scully KD, Farkas E, Herreras O, Kirov SA, Müller M, Ollen-Bittle N, Reiffurth C, Revah O, Robertson RM, Shuttleworth CW, Ullah G, Dreier JP. The Critical Role of Spreading Depolarizations in Early Brain Injury: Consensus and Contention. Neurocrit Care 2022; 37:83-101. [PMID: 35257321 PMCID: PMC9259543 DOI: 10.1007/s12028-021-01431-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 12/29/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND When a patient arrives in the emergency department following a stroke, a traumatic brain injury, or sudden cardiac arrest, there is no therapeutic drug available to help protect their jeopardized neurons. One crucial reason is that we have not identified the molecular mechanisms leading to electrical failure, neuronal swelling, and blood vessel constriction in newly injured gray matter. All three result from a process termed spreading depolarization (SD). Because we only partially understand SD, we lack molecular targets and biomarkers to help neurons survive after losing their blood flow and then undergoing recurrent SD. METHODS In this review, we introduce SD as a single or recurring event, generated in gray matter following lost blood flow, which compromises the Na+/K+ pump. Electrical recovery from each SD event requires so much energy that neurons often die over minutes and hours following initial injury, independent of extracellular glutamate. RESULTS We discuss how SD has been investigated with various pitfalls in numerous experimental preparations, how overtaxing the Na+/K+ ATPase elicits SD. Elevated K+ or glutamate are unlikely natural activators of SD. We then turn to the properties of SD itself, focusing on its initiation and propagation as well as on computer modeling. CONCLUSIONS Finally, we summarize points of consensus and contention among the authors as well as where SD research may be heading. In an accompanying review, we critique the role of the glutamate excitotoxicity theory, how it has shaped SD research, and its questionable importance to the study of early brain injury as compared with SD theory.
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Affiliation(s)
- R. David Andrew
- grid.410356.50000 0004 1936 8331Queen’s University, Kingston, ON Canada
| | - Jed A. Hartings
- grid.24827.3b0000 0001 2179 9593University of Cincinnati, Cincinnati, OH USA
| | - Cenk Ayata
- grid.38142.3c000000041936754XHarvard Medical School, Harvard University, Boston, MA USA
| | - K. C. Brennan
- grid.223827.e0000 0001 2193 0096The University of Utah, Salt Lake City, UT USA
| | | | - Eszter Farkas
- grid.9008.10000 0001 1016 96251HCEMM-USZ Cerebral Blood Flow and Metabolism Research Group, and the Department of Cell Biology and Molecular Medicine, Faculty of Science and Informatics & Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Oscar Herreras
- grid.419043.b0000 0001 2177 5516Instituto de Neurobiologia Ramon Y Cajal (Consejo Superior de Investigaciones Científicas), Madrid, Spain
| | - Sergei. A. Kirov
- grid.410427.40000 0001 2284 9329Medical College of Georgia, Augusta, GA USA
| | - Michael Müller
- grid.411984.10000 0001 0482 5331University of Göttingen, University Medical Center Göttingen, Göttingen, Germany
| | - Nikita Ollen-Bittle
- grid.39381.300000 0004 1936 8884University of Western Ontario, London, ON Canada
| | - Clemens Reiffurth
- grid.7468.d0000 0001 2248 7639Center for Stroke Research Berlin, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health; and the Department of Experimental Neurology, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health., Berlin, Germany
| | - Omer Revah
- grid.168010.e0000000419368956School of Medicine, Stanford University, Stanford, CA USA
| | | | | | - Ghanim Ullah
- grid.170693.a0000 0001 2353 285XUniversity of South Florida, Tampa, FL USA
| | - Jens P. Dreier
- grid.7468.d0000 0001 2248 7639Center for Stroke Research Berlin, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health; and the Department of Experimental Neurology, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health., Berlin, Germany
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13
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Venkataraman G, Shabala S, Véry AA, Hariharan GN, Somasundaram S, Pulipati S, Sellamuthu G, Harikrishnan M, Kumari K, Shabala L, Zhou M, Chen ZH. To exclude or to accumulate? Revealing the role of the sodium HKT1;5 transporter in plant adaptive responses to varying soil salinity. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 169:333-342. [PMID: 34837866 DOI: 10.1016/j.plaphy.2021.11.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/13/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
Arid/semi-arid and coastal agricultural areas of the world are especially vulnerable to climate change-driven soil salinity. Salinity tolerance in plants is a complex trait, with salinity negatively affecting crop yield. Plants adopt a range of mechanisms to combat salinity, with many transporter genes being implicated in Na+-partitioning processes. Within these, the high-affinity K+ (HKT) family of transporters play a critical role in K+ and Na+ homeostasis in plants. Among HKT transporters, Type I transporters are Na+-specific. While Arabidopsis has only one Na + -specific HKT (AtHKT1;1), cereal crops have a multiplicity of Type I and II HKT transporters. AtHKT1; 1 (Arabidopsis thaliana) and HKT1; 5 (cereal crops) 'exclude' Na+ from the xylem into xylem parenchyma in the root, reducing shoot Na+ and hence, confer sodium tolerance. However, more recent data from Arabidopsis and crop species show that AtHKT1;1/HKT1;5 alleles have a strong genetic association with 'shoot sodium accumulation' and concomitant salt tolerance. The review tries to resolve these two seemingly contradictory effects of AtHKT1;1/HKT1;5 operation (shoot exclusion vs shoot accumulation), both conferring salinity tolerance and suggests that contrasting phenotypes are attributable to either hyper-functional or weak AtHKT1;1/HKT1;5 alleles/haplotypes and are under strong selection by soil salinity levels. It also suggests that opposite balancing mechanisms involving xylem ion loading in these contrasting phenotypes exist that require transporters such as SOS1 and CCC. While HKT1; 5 is a crucial but not sole determinant of salinity tolerance, investigation of the adaptive benefit(s) conferred by naturally occurring intermediate HKT1;5 alleles will be important under a climate change scenario.
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Affiliation(s)
- Gayatri Venkataraman
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, 600113, India.
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas, 7001, Australia; International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, 528000, China.
| | - Anne-Aliénor Véry
- Biochimie & Physiologie Moléculaire des Plantes, UMR Univ. Montpellier, CNRS, INRAE, Institut Agro, 34060, Montpellier Cedex 2, France.
| | - Gopalasamudram Neelakantan Hariharan
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, 600113, India
| | - Suji Somasundaram
- Department of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai, 600124, India
| | - Shalini Pulipati
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, 600113, India
| | - Gothandapani Sellamuthu
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, 600113, India; Forest Molecular Entomology Laboratory, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague (CZU), Kamycka 129, Praha, 16500, Czech Republic
| | - Mohan Harikrishnan
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, 600113, India
| | - Kumkum Kumari
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai, 600113, India
| | - Lana Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas, 7001, Australia
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas, 7001, Australia
| | - Zhong-Hua Chen
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
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14
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Cation Transporters of Candida albicans-New Targets to Fight Candidiasis? Biomolecules 2021; 11:biom11040584. [PMID: 33923411 PMCID: PMC8073359 DOI: 10.3390/biom11040584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 04/14/2021] [Indexed: 02/07/2023] Open
Abstract
Candidiasis is the wide-spread fungal infection caused by numerous strains of yeast, with the prevalence of Candida albicans. The current treatment of candidiasis is becoming rather ineffective and costly owing to the emergence of resistant strains; hence, the exploration of new possible drug targets is necessary. The most promising route is the development of novel antibiotics targeting this pathogen. In this review, we summarize such candidates found in C. albicans and those involved in the transport of (metal) cations, as the latter are essential for numerous processes within the cell; hence, disruption of their fluxes can be fatal for C. albicans.
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15
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Stautz J, Hellmich Y, Fuss MF, Silberberg JM, Devlin JR, Stockbridge RB, Hänelt I. Molecular Mechanisms for Bacterial Potassium Homeostasis. J Mol Biol 2021; 433:166968. [PMID: 33798529 DOI: 10.1016/j.jmb.2021.166968] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/11/2021] [Accepted: 03/22/2021] [Indexed: 10/21/2022]
Abstract
Potassium ion homeostasis is essential for bacterial survival, playing roles in osmoregulation, pH homeostasis, regulation of protein synthesis, enzyme activation, membrane potential adjustment and electrical signaling. To accomplish such diverse physiological tasks, it is not surprising that a single bacterium typically encodes several potassium uptake and release systems. To understand the role each individual protein fulfills and how these proteins work in concert, it is important to identify the molecular details of their function. One needs to understand whether the systems transport ions actively or passively, and what mechanisms or ligands lead to the activation or inactivation of individual systems. Combining mechanistic information with knowledge about the physiology under different stress situations, such as osmostress, pH stress or nutrient limitation, one can identify the task of each system and deduce how they are coordinated with each other. By reviewing the general principles of bacterial membrane physiology and describing the molecular architecture and function of several bacterial K+-transporting systems, we aim to provide a framework for microbiologists studying bacterial potassium homeostasis and the many K+-translocating systems that are still poorly understood.
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Affiliation(s)
- Janina Stautz
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Yvonne Hellmich
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Michael F Fuss
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jakob M Silberberg
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jason R Devlin
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Randy B Stockbridge
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States.
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.
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16
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Fernandes AS, Pombinho A, Teixeira-Duarte CM, Morais-Cabral JH, Harley CA. Fluorometric Liposome Screen for Inhibitors of a Physiologically Important Bacterial Ion Channel. Front Microbiol 2021; 12:603700. [PMID: 33732218 PMCID: PMC7956971 DOI: 10.3389/fmicb.2021.603700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 02/01/2021] [Indexed: 11/13/2022] Open
Abstract
The bacterial K+ homeostasis machinery is widely conserved across bacterial species, and different from that in animals. Dysfunction in components of the machinery has an impact on intracellular turgor, membrane potential, adaptation to changes in both extracellular pH and osmolarity, and in virulence. Using a fluorescence-based liposome flux assay, we have performed a high-throughput screen to identify novel inhibitors of the KtrAB ion channel complex from Bacillus subtilis, a component of the K+ homeostasis machinery that is also present in many bacterial pathogens. The screen identified 41 compounds that inhibited K+ flux and that clustered into eight chemical groups. Many of the identified inhibitors were found to target KtrAB with an in vitro potency in the low μM range. We investigated the mechanisms of inhibition and found that most molecules affected either the membrane component of the channel, KtrB alone or the full KtrAB complex without a preference for the functional conformation of the channel, thus broadening their inhibitory action. A urea derivative molecule that inhibited the membrane component of KtrAB affected cell viability in conditions in which KtrAB activity is essential. With this proof-of-concept study, we demonstrate that targeting components of the K+ homeostasis machinery has the potential as a new antibacterial strategy and that the fluorescence-based flux assay is a robust tool for screening chemical libraries.
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Affiliation(s)
- Andreia S Fernandes
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - António Pombinho
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Celso M Teixeira-Duarte
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Carol A Harley
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
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17
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Shamayeva K, Spurna K, Kulik N, Kale D, Munko O, Spurny P, Zayats V, Ludwig J. MPM motifs of the yeast SKT protein Trk1 can assemble to form a functional K +-translocation system. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183513. [PMID: 33245894 DOI: 10.1016/j.bbamem.2020.183513] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 11/14/2020] [Accepted: 11/18/2020] [Indexed: 10/22/2022]
Abstract
The yeast Trk1 polypeptide, like other members of the Superfamily of K Transporters (SKT proteins) consists of four Membrane-Pore-Membrane motifs (MPMs A-D) each of which is homologous to a single K-channel subunit. SKT proteins are thought to have evolved from ancestral K-channels via two gene duplications and thus single MPMs might be able to assemble when located on different polypeptides. To test this hypothesis experimentally we generated a set of partial gene deletions to create alleles encoding one, two, or three MPMs, and analysed the cellular localisation and interactions of these Trk1 fragments using GFP tags and Bimolecular Fluorescence Complementation (BiFC). The function of these partial Trk1 proteins either alone or in combinations was assessed by expressing the encoding genes in a K+-uptake deficient strain lacking also the K-channel Tok1 (trk1,trk2,tok1Δ) and (i) analysing their ability to promote growth in low [K+] media and (ii) by ion flux measurements using "microelectrode based ion flux estimation" (MIFE). We found that proteins containing only one or two MPM motifs can interact with each other and assemble with a polypeptide consisting of the rest of the Trk system to form a functional K+-translocation system.
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Affiliation(s)
- Katsiaryna Shamayeva
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic.
| | - Karin Spurna
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic.
| | - Natalia Kulik
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic.
| | - Deepika Kale
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic.
| | - Oksana Munko
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic; University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 1760, 370 05 Ceske Budejovice, Czech Republic.
| | - Pavel Spurny
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic.
| | - Vasilina Zayats
- Centre of New Technologies, University of Warsaw, Stefana Banacha 2c, 02-097 Warsaw, Poland.
| | - Jost Ludwig
- Center for Nanobiology and Structural Biology, Institute of Microbiology of the Czech Academy of Sciences, Zamek 136, 373 33 Nove Hrady, Czech Republic.
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18
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Schrecker M, Wunnicke D, Hänelt I. How RCK domains regulate gating of K+ channels. Biol Chem 2020; 400:1303-1322. [PMID: 31361596 DOI: 10.1515/hsz-2019-0153] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Accepted: 07/02/2019] [Indexed: 11/15/2022]
Abstract
Potassium channels play a crucial role in the physiology of all living organisms. They maintain the membrane potential and are involved in electrical signaling, pH homeostasis, cell-cell communication and survival under osmotic stress. Many prokaryotic potassium channels and members of the eukaryotic Slo channels are regulated by tethered cytoplasmic domains or associated soluble proteins, which belong to the family of regulator of potassium conductance (RCK). RCK domains and subunits form octameric rings, which control ion gating. For years, a common regulatory mechanism was suggested: ligand-induced conformational changes in the octameric ring would pull open a gate in the pore via flexible linkers. Consistently, ligand-dependent conformational changes were described for various RCK gating rings. Yet, recent structural and functional data of complete ion channels uncovered that the following signal transduction to the pore domains is divers. The different RCK-regulated ion channels show remarkably heterogeneous mechanisms with neither the connection from the RCK domain to the pore nor the gate being conserved. Some channels even lack the flexible linkers, while in others the gate cannot easily be assigned. In this review we compare available structures of RCK-gated potassium channels, highlight the similarities and differences of channel gating, and delineate existing inconsistencies.
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Affiliation(s)
- Marina Schrecker
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt Main, Germany
| | - Dorith Wunnicke
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt Main, Germany
| | - Inga Hänelt
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, D-60438 Frankfurt Main, Germany
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19
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TrkA undergoes a tetramer-to-dimer conversion to open TrkH which enables changes in membrane potential. Nat Commun 2020; 11:547. [PMID: 31992706 PMCID: PMC6987127 DOI: 10.1038/s41467-019-14240-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 12/11/2019] [Indexed: 01/07/2023] Open
Abstract
TrkH is a bacterial ion channel implicated in K+ uptake and pH regulation. TrkH assembles with its regulatory protein, TrkA, which closes the channel when bound to ADP and opens it when bound to ATP. However, it is unknown how nucleotides control the gating of TrkH through TrkA. Here we report the structures of the TrkH-TrkA complex in the presence of ADP or ATP. TrkA forms a tetrameric ring when bound to ADP and constrains TrkH to a closed conformation. The TrkA ring splits into two TrkA dimers in the presence of ATP and releases the constraints on TrkH, resulting in an open channel conformation. Functional studies show that both the tetramer-to-dimer conversion of TrkA and the loss of constraints on TrkH are required for channel gating. In addition, deletion of TrkA in Escherichia coli depolarizes the cell, suggesting that the TrkH-TrkA complex couples changes in intracellular nucleotides to membrane potential.
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20
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Hmidi D, Messedi D, Corratgï-Faillie C, Marhuenda TO, Fizames CC, Zorrig W, Abdelly C, Sentenac H, Vï Ry AAN. Investigation of Na+ and K+ Transport in Halophytes: Functional Analysis of the HmHKT2;1 Transporter from Hordeum maritimum and Expression under Saline Conditions. PLANT & CELL PHYSIOLOGY 2019; 60:2423-2435. [PMID: 31292634 DOI: 10.1093/pcp/pcz136] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 07/04/2019] [Indexed: 06/09/2023]
Abstract
Control of K+ and Na+ transport plays a central role in plant adaptation to salinity. In the halophyte Hordeum maritimum, we have characterized a transporter gene, named HmHKT2;1, whose homolog HvHKT2;1 in cultivated barley, Hordeum vulgare, was known to give rise to increased salt tolerance when overexpressed. The encoded protein is strictly identical in two H. maritimum ecotypes, from two biotopes (Tunisian sebkhas) affected by different levels of salinity. These two ecotypes were found to display distinctive responses to salt stress in terms of biomass production, Na+ contents, K+ contents and K+ absorption efficiency. Electrophysiological analysis of HmHKT2;1 in Xenopus oocytes revealed distinctive properties when compared with HvHKT2;1 and other transporters from the same group, especially a much higher affinity for both Na+ and K+, and an Na+-K+ symporter behavior in a very broad range of Na+ and K+ concentrations, due to reduced K+ blockage of the transport pathway. Domain swapping experiments identified the region including the fifth transmembrane segment and the adjacent extracellular loop as playing a major role in the determination of the affinity for Na+ and the level of K+ blockage in these HKT2;1 transporters. The analysis (quantitative reverse transcription-PCR; qRT-PCR) of HmHKT2;1 expression in the two ecotypes submitted to saline conditions revealed that the levels of HmHKT2;1 transcripts were maintained constant in the most salt-tolerant ecotype whereas they decreased in the less tolerant one. Both the unique functional properties of HmHKT2;1 and the regulation of the expression of the encoding gene could contribute to H. maritimum adaptation to salinity.
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Affiliation(s)
- Dorsaf Hmidi
- Biochimie et Physiologie Mol�culaire des Plantes, Univ Montpellier, CNRS, INRA, SupAgro Montpellier, Campus SupAgro-INRA, Montpellier Cedex 2, France
- Laboratoire des Plantes Extr�mophiles, BP 901, Centre de Biotechnologie, Technopole de Borj C�dria, HammamLif, Tunisia
| | - Dorsaf Messedi
- Laboratoire des Plantes Extr�mophiles, BP 901, Centre de Biotechnologie, Technopole de Borj C�dria, HammamLif, Tunisia
| | - Claire Corratgï-Faillie
- Biochimie et Physiologie Mol�culaire des Plantes, Univ Montpellier, CNRS, INRA, SupAgro Montpellier, Campus SupAgro-INRA, Montpellier Cedex 2, France
| | - Thï O Marhuenda
- Biochimie et Physiologie Mol�culaire des Plantes, Univ Montpellier, CNRS, INRA, SupAgro Montpellier, Campus SupAgro-INRA, Montpellier Cedex 2, France
| | - Cï Cile Fizames
- Biochimie et Physiologie Mol�culaire des Plantes, Univ Montpellier, CNRS, INRA, SupAgro Montpellier, Campus SupAgro-INRA, Montpellier Cedex 2, France
| | - Walid Zorrig
- Laboratoire des Plantes Extr�mophiles, BP 901, Centre de Biotechnologie, Technopole de Borj C�dria, HammamLif, Tunisia
| | - Chedly Abdelly
- Laboratoire des Plantes Extr�mophiles, BP 901, Centre de Biotechnologie, Technopole de Borj C�dria, HammamLif, Tunisia
| | - Hervï Sentenac
- Biochimie et Physiologie Mol�culaire des Plantes, Univ Montpellier, CNRS, INRA, SupAgro Montpellier, Campus SupAgro-INRA, Montpellier Cedex 2, France
| | - Anne-Aliï Nor Vï Ry
- Biochimie et Physiologie Mol�culaire des Plantes, Univ Montpellier, CNRS, INRA, SupAgro Montpellier, Campus SupAgro-INRA, Montpellier Cedex 2, France
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21
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Kale D, Spurny P, Shamayeva K, Spurna K, Kahoun D, Ganser D, Zayats V, Ludwig J. The S. cerevisiae cation translocation protein Trk1 is functional without its “long hydrophilic loop” but LHL regulates cation translocation activity and selectivity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1476-1488. [DOI: 10.1016/j.bbamem.2019.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 06/14/2019] [Accepted: 06/17/2019] [Indexed: 10/26/2022]
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22
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Zhu L, Shahid MA, Markham J, Browning GF, Noormohammadi AH, Marenda MS. Comparative genomic analyses of Mycoplasma synoviae vaccine strain MS-H and its wild-type parent strain 86079/7NS: implications for the identification of virulence factors and applications in diagnosis of M. synoviae. Avian Pathol 2019; 48:537-548. [PMID: 31244324 DOI: 10.1080/03079457.2019.1637514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mycoplasma synoviae is an economically important avian pathogen worldwide, causing respiratory disease, infectious synovitis, airsacculitis and eggshell apex abnormalities in commercial chickens. Despite the widespread use of MS-H as a live attenuated vaccine over the past two decades, the precise molecular basis for loss of virulence in this vaccine is not yet fully understood. To address this, the whole genome sequence of the vaccine parent strain, 86079/7NS, was obtained and compared to that of the MS-H vaccine. Except for the vlhA expressed region, both genomes were nearly identical. Thirty-two single nucleotide polymorphisms (SNPs) were identified in MS-H, including 11 non-synonymous mutations that were predicted, by bioinformatics analysis, to have changed the secondary structure of the deduced proteins. One of these mutations caused truncation of the oppF-1 gene, which encodes the ATP-binding protein of an oligopeptide permease transporter. Overall, the attenuation of MS-H strain may be caused by the cumulative and complex effects of several mutations. The SNPs identified in MS-H were further analyzed by comparing the MS-H and 86079/7NS sequences with the strains WVU-1853 and MS53. In the genomic regions conserved between all strains, 30 SNPs were found to be unique to MS-H lineage. These results have provided a foundation for developing novel biomarkers for the detection of virulence in M. synoviae and also for designing new genotyping assays for discrimination of MS-H from field strains.
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Affiliation(s)
- Ling Zhu
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Werribee , Australia
| | - Muhammad A Shahid
- Department of Pathobiology, Faculty of Veterinary Sciences, Bahauddin Zakariya University , Multan , Pakistan
| | - John Markham
- Department of Electrical and Electronic Engineering, the University of Melbourne , Parkville , Australia
| | - Glenn F Browning
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Parkville , Australia
| | - Amir H Noormohammadi
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Werribee , Australia
| | - Marc S Marenda
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Werribee , Australia
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Overexpression of PeHKT1;1 Improves Salt Tolerance in Populus. Genes (Basel) 2018; 9:genes9100475. [PMID: 30274294 PMCID: PMC6210203 DOI: 10.3390/genes9100475] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/21/2018] [Accepted: 09/25/2018] [Indexed: 02/03/2023] Open
Abstract
Soil salinization is an increasingly serious threat that limits plant growth and development. Class I transporters of the high-affinity K+ transporter (HKT) family have been demonstrated to be involved in salt tolerance by contributing to Na+ exclusion from roots and shoots. Here, we isolated the PeHKT1;1 gene from hybrid poplar based on the sequences of the Populus trichocarpa genome. The full-length PeHKT1;1 gene was 2173 bp, including a 1608 bp open reading frame (ORF) encoding 535 amino acids and containing eight distinct transmembrane domains. Multiple sequence alignment and phylogenetic analysis suggested that the PeHKT1;1 protein had a typical S–G–G–G signature for the P-loop domains and belonged to class I of HKT transporters. PeHKT1;1 transcripts were mainly detected in stem and root, and were remarkably induced by salt stress treatment. In further characterization of its functions, overexpression of PeHKT1;1 in Populus davidiana × Populus bolleana resulted in a better relative growth rate in phenotypic analysis, including root and plant height, and exhibited higher catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities than non-transgenic poplar under salt stress conditions. These observations indicated that PeHKT1;1 may enhance salt tolerance by improving the efficiency of antioxidant systems. Together, these data suggest that PeHKT1;1 plays an important role in response to salt stress in Populus.
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Ali A, Raddatz N, Aman R, Kim S, Park HC, Jan M, Baek D, Khan IU, Oh DH, Lee SY, Bressan RA, Lee KW, Maggio A, Pardo JM, Bohnert HJ, Yun DJ. A Single Amino-Acid Substitution in the Sodium Transporter HKT1 Associated with Plant Salt Tolerance. PLANT PHYSIOLOGY 2016; 171:2112-26. [PMID: 27208305 PMCID: PMC4936583 DOI: 10.1104/pp.16.00569] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 05/06/2016] [Indexed: 05/20/2023]
Abstract
A crucial prerequisite for plant growth and survival is the maintenance of potassium uptake, especially when high sodium surrounds the root zone. The Arabidopsis HIGH-AFFINITY K(+) TRANSPORTER1 (HKT1), and its homologs in other salt-sensitive dicots, contributes to salinity tolerance by removing Na(+) from the transpiration stream. However, TsHKT1;2, one of three HKT1 copies in Thellungiella salsuginea, a halophytic Arabidopsis relative, acts as a K(+) transporter in the presence of Na(+) in yeast (Saccharomyces cerevisiae). Amino-acid sequence comparisons indicated differences between TsHKT1;2 and most other published HKT1 sequences with respect to an Asp residue (D207) in the second pore-loop domain. Two additional T salsuginea and most other HKT1 sequences contain Asn (n) in this position. Wild-type TsHKT1;2 and altered AtHKT1 (AtHKT1(N-D)) complemented K(+)-uptake deficiency of yeast cells. Mutant hkt1-1 plants complemented with both AtHKT1(N) (-) (D) and TsHKT1;2 showed higher tolerance to salt stress than lines complemented by the wild-type AtHKT1 Electrophysiological analysis in Xenopus laevis oocytes confirmed the functional properties of these transporters and the differential selectivity for Na(+) and K(+) based on the n/d variance in the pore region. This change also dictated inward-rectification for Na(+) transport. Thus, the introduction of Asp, replacing Asn, in HKT1-type transporters established altered cation selectivity and uptake dynamics. We describe one way, based on a single change in a crucial protein that enabled some crucifer species to acquire improved salt tolerance, which over evolutionary time may have resulted in further changes that ultimately facilitated colonization of saline habitats.
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Affiliation(s)
- Akhtar Ali
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Natalia Raddatz
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Rashid Aman
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Songmi Kim
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Hyeong Cheol Park
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Masood Jan
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Dongwon Baek
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Irfan Ullah Khan
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Dong-Ha Oh
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Sang Yeol Lee
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Ray A Bressan
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Keun Woo Lee
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Albino Maggio
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Jose M Pardo
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Hans J Bohnert
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
| | - Dae-Jin Yun
- Division of Applied Life Science (BK21 Plus Program), Gyeongsang National University, Jinju 660-701, Republic of Korea (A.A., R.A., S.K., M.J., D.B., I.U.K., S.Y.L., K.W.L., H.J.B., D.-J.Y.); Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Carretera M-40, km 37.7, E-28223 Pozuelo de Alarcón Madrid (N.R.);Division of Ecological Adaptation Research, National Institute of Ecology (NIE), Seocheon 325-813, Republic of Korea (H.C.P.); Department of Biology, Louisiana State University, Baton Rouge, Louisiana 70803 (D.-H.O.);Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-2010 (R.A.B.);Department of Agriculture, University of Naples Federico II, Via Universita` 100, Portici, I-80055, Italy (A.M.);Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Cientificas, 41092 Sevilla, Spain (J.M.P.); College of Science, King Abdulaziz University, Jeddah 21589, KSA (H.J.B.); and Department of Plant Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801 (H.J.B.)
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Elicharová H, Hušeková B, Sychrová H. ThreeCandida albicanspotassium uptake systems differ in their ability to provideSaccharomyces cerevisiae trk1trk2mutants with necessary potassium. FEMS Yeast Res 2016; 16:fow039. [DOI: 10.1093/femsyr/fow039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2016] [Indexed: 12/31/2022] Open
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Ariyarathna HACK, Francki MG. Phylogenetic relationships and protein modelling revealed two distinct subfamilies of group II HKT genes between crop and model grasses. Genome 2016; 59:509-17. [PMID: 27203707 DOI: 10.1139/gen-2016-0035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Molecular evolution of large protein families in closely related species can provide useful insights on structural functional relationships. Phylogenetic analysis of the grass-specific group II HKT genes identified two distinct subfamilies, I and II. Subfamily II was represented in all species, whereas subfamily I was identified only in the small grain cereals and possibly originated from an ancestral gene duplication post divergence from the coarse grain cereal lineage. The core protein structures were highly analogous despite there being no more than 58% amino acid identity between members of the two subfamilies. Distinctly variable regions in known functional domains, however, indicated functional divergence of the two subfamilies. The subsets of codons residing external to known functional domains predicted signatures of positive Darwinian selection potentially identifying new domains of functional divergence and providing new insights on the structural function and relationships between protein members of the two subfamilies.
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Affiliation(s)
- H A Chandima K Ariyarathna
- a School of Plant Biology and Institute of Agriculture, The University of Western Australia, Crawley WA 6009, Australia.,b State Agricultural Biotechnology Centre, Murdoch University, Murdoch WA 6150, Australia
| | - Michael G Francki
- b State Agricultural Biotechnology Centre, Murdoch University, Murdoch WA 6150, Australia.,c Department of Agriculture and Food Western Australia, 3 Baron Hay Ct, South Perth WA 6151, Australia
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Checchetto V, Segalla A, Sato Y, Bergantino E, Szabo I, Uozumi N. Involvement of Potassium Transport Systems in the Response of Synechocystis PCC 6803 Cyanobacteria to External pH Change, High-Intensity Light Stress and Heavy Metal Stress. PLANT & CELL PHYSIOLOGY 2016; 57:862-877. [PMID: 26880819 DOI: 10.1093/pcp/pcw032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/04/2016] [Indexed: 06/05/2023]
Abstract
The unicellular photosynthetic cyanobacterium, able to survive in varying environments, is the only prokaryote that directly converts solar energy and CO2 into organic material and is thus relevant for primary production in many ecosystems. To maintain the intracellular and intrathylakoid ion homeostasis upon different environmental challenges, the concentration of potassium as a major intracellular cation has to be optimized by various K(+)uptake-mediated transport systems. We reveal here the specific and concerted physiological function of three K(+)transporters of the plasma and thylakoid membranes, namely of SynK (K(+)channel), KtrB (Ktr/Trk/HKT) and KdpA (Kdp) in Synechocystis sp. strain PCC 6803, under specific stress conditions. The behavior of the wild type, single, double and triple mutants was compared, revealing that only Synk contributes to heavy metal-induced stress, while only Ktr/Kdp is involved in osmotic and salt stress adaptation. With regards to pH shifts in the external medium, the Kdp/Ktr uptake systems play an important role in the adaptation to acidic pH. Ktr, by affecting the CO2 concentration mechanism via its action on the bicarbonate transporter SbtA, might also be responsible for the observed effects concerning high-light stress and calcification. In the case of illumination with high-intensity light, a synergistic action of Kdr/Ktp and SynK is required in order to avoid oxidative stress and ensure cell viability. In summary, this study dissects, using growth tests, measurement of photosynthetic activity and analysis of ultrastructure, the physiological role of three K(+)transporters in adaptation of the cyanobacteria to various environmental changes.
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Affiliation(s)
- Vanessa Checchetto
- Department of Biology, University of Padova, Padova 35121, Italy Department of Biomedical Sciences, University of Padova, Padova 35121, Italy
| | - Anna Segalla
- Department of Biology, University of Padova, Padova 35121, Italy
| | - Yuki Sato
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, 980-8579 Japan
| | | | - Ildiko Szabo
- Department of Biology, University of Padova, Padova 35121, Italy
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, 980-8579 Japan
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Suzuki K, Yamaji N, Costa A, Okuma E, Kobayashi NI, Kashiwagi T, Katsuhara M, Wang C, Tanoi K, Murata Y, Schroeder JI, Ma JF, Horie T. OsHKT1;4-mediated Na(+) transport in stems contributes to Na(+) exclusion from leaf blades of rice at the reproductive growth stage upon salt stress. BMC PLANT BIOLOGY 2016; 16:22. [PMID: 26786707 PMCID: PMC4719677 DOI: 10.1186/s12870-016-0709-4] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 01/11/2016] [Indexed: 05/02/2023]
Abstract
BACKGROUND Na(+) exclusion from leaf blades is one of the key mechanisms for glycophytes to cope with salinity stress. Certain class I transporters of the high-affinity K(+) transporter (HKT) family have been demonstrated to mediate leaf blade-Na(+) exclusion upon salinity stress via Na(+)-selective transport. Multiple HKT1 transporters are known to function in rice (Oryza sativa). However, the ion transport function of OsHKT1;4 and its contribution to the Na(+) exclusion mechanism in rice remain to be elucidated. RESULTS Here, we report results of the functional characterization of the OsHKT1;4 transporter in rice. OsHKT1;4 mediated robust Na(+) transport in Saccharomyces cerevisiae and Xenopus laevis oocytes. Electrophysiological experiments demonstrated that OsHKT1;4 shows strong Na(+) selectivity among cations tested, including Li(+), Na(+), K(+), Rb(+), Cs(+), and NH4 (+), in oocytes. A chimeric protein, EGFP-OsHKT1;4, was found to be functional in oocytes and targeted to the plasma membrane of rice protoplasts. The level of OsHKT1;4 transcripts was prominent in leaf sheaths throughout the growth stages. Unexpectedly however, we demonstrate here accumulation of OsHKT1;4 transcripts in the stem including internode II and peduncle in the reproductive growth stage. Moreover, phenotypic analysis of OsHKT1;4 RNAi plants in the vegetative growth stage revealed no profound influence on the growth and ion accumulation in comparison with WT plants upon salinity stress. However, imposition of salinity stress on the RNAi plants in the reproductive growth stage caused significant Na(+) overaccumulation in aerial organs, in particular, leaf blades and sheaths. In addition, (22)Na(+) tracer experiments using peduncles of RNAi and WT plants suggested xylem Na(+) unloading by OsHKT1;4. CONCLUSIONS Taken together, our results indicate a newly recognized function of OsHKT1;4 in Na(+) exclusion in stems together with leaf sheaths, thus excluding Na(+) from leaf blades of a japonica rice cultivar in the reproductive growth stage, but the contribution is low when the plants are in the vegetative growth stage.
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Grants
- P42 ES010337 NIEHS NIH HHS
- P42ES010337 NIEHS NIH HHS
- Ministry of Education, Culture, Sports, Science, and Technology (JP)
- Ministry of Education, Culture, Sports, Science, and Technology as part of the Joint Research Program implemented at the Institute of Plant Science and Resources, Okayama University (JP)
- Public Foundation of Chubu Science and Technology Center (JP)
- Ministero dell’Istruzione, dell’Università e della Ricerca Fondo per gli Investimenti della Ricerca di Base (FIRB) 2010
- National Institutes of Health (US)
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Affiliation(s)
- Kei Suzuki
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano, 386-8567, Japan.
| | - Naoki Yamaji
- Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, 710-0046, Japan.
| | - Alex Costa
- Department of Biosciences, University of Milan, Via G. Celoria 26, 20133, Milan, Italy.
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via G. Celoria 26, 20133, Milan, Italy.
| | - Eiji Okuma
- Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Okayama, 700-8530, Japan.
| | - Natsuko I Kobayashi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Tatsuhiko Kashiwagi
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano, 386-8567, Japan.
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, 710-0046, Japan.
| | - Cun Wang
- Division of Biological Sciences, Cell and Developmental Biology Section, University of California, SanDiego, La Jolla, CA, 92093-0116, USA.
| | - Keitaro Tanoi
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Yoshiyuki Murata
- Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Okayama, 700-8530, Japan.
| | - Julian I Schroeder
- Division of Biological Sciences, Cell and Developmental Biology Section, University of California, SanDiego, La Jolla, CA, 92093-0116, USA.
| | - Jian Feng Ma
- Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, 710-0046, Japan.
| | - Tomoaki Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano, 386-8567, Japan.
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Szollosi A, Vieira-Pires RS, Teixeira-Duarte CM, Rocha R, Morais-Cabral JH. Dissecting the Molecular Mechanism of Nucleotide-Dependent Activation of the KtrAB K+ Transporter. PLoS Biol 2016; 14:e1002356. [PMID: 26771197 PMCID: PMC4714889 DOI: 10.1371/journal.pbio.1002356] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 12/10/2015] [Indexed: 11/18/2022] Open
Abstract
KtrAB belongs to the Trk/Ktr/HKT superfamily of monovalent cation (K+ and Na+) transport proteins that closely resemble K+ channels. These proteins underlie a plethora of cellular functions that are crucial for environmental adaptation in plants, fungi, archaea, and bacteria. The activation mechanism of the Trk/Ktr/HKT proteins remains unknown. It has been shown that ATP stimulates the activity of KtrAB while ADP does not. Here, we present X-ray structural information on the KtrAB complex with bound ADP. A comparison with the KtrAB-ATP structure reveals conformational changes in the ring and in the membrane protein. In combination with a biochemical and functional analysis, we uncover how ligand-dependent changes in the KtrA ring are propagated to the KtrB membrane protein and conclude that, despite their structural similarity, the activation mechanism of KtrAB is markedly different from the activation mechanism of K+ channels. This study reveals how structural changes triggered by the exchange of bound ADP for ATP activate KtrAB, a potassium ion transporter involved in osmotic adaption in bacteria. Animals have organs that regulate the balance of water and ions in the fluids bathing their cells. In contrast, the cells of plants, bacteria, and fungi have little or no control over those fluids and, thus, they have to cope with changes in the local environment. These cells have therefore evolved specific molecular systems that are crucial for environmental adaptation. We study the molecular properties of the membrane protein KtrAB—a member of the Trk/Ktr/HKT superfamily of transport proteins that shuffle K+ and Na+ ions across the plasma membrane, closely resemble K+ channels, and underlie environmental adaptation of cells of plants, fungi, bacteria, and archaea. KtrAB is formed by the KtrB membrane protein and the KtrA cytosolic ring protein. KtrA binds to both ADP and ATP, resulting in a low-activity ADP-bound state and a high-activity ATP-bound state, respectively. We determined a low resolution structure of a low-activity form of the transport protein. A comparison of this structure with the structure of ATP-bound KtrAB reveals changes in both the KtrA ring and the KtrB membrane protein. We uncover how changes in the KtrA ring are propagated to KtrB and conclude that, despite their structural similarity, the activation mechanism of KtrAB is markedly different from the activation mechanism of K+ channels.
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Affiliation(s)
- Andras Szollosi
- IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | | | - Celso M. Teixeira-Duarte
- IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Rita Rocha
- IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - João H. Morais-Cabral
- IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- * E-mail:
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30
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Suzuki K, Costa A, Nakayama H, Katsuhara M, Shinmyo A, Horie T. OsHKT2;2/1-mediated Na(+) influx over K(+) uptake in roots potentially increases toxic Na(+) accumulation in a salt-tolerant landrace of rice Nona Bokra upon salinity stress. JOURNAL OF PLANT RESEARCH 2016; 129:67-77. [PMID: 26578190 DOI: 10.1007/s10265-015-0764-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/18/2015] [Indexed: 05/10/2023]
Abstract
HKT transporters are Na(+)-permeable membrane proteins, which mediate Na(+) and K(+) homeostasis in K(+)-depleted and saline environments in plants. Class II HKT transporters, a distinct subgroup found predominantly in monocots, are known to mediate Na(+)-K(+) co-transport in principle. Here we report features of ion transport functions of No-OsHKT2;2/1, a class II transporter identified in a salt tolerant landrace of indica rice, Nona Bokra. We profiled No-OsHKT2;2/1 expression in organs of Nona Bokra plants with or without salinity stress. Dominant accumulation of the No-OsHKT2;2/1 transcript in K(+)-starved roots of Nona Bokra plants largely disappeared in response to 50 mM NaCl. We found that No-OsHKT2;2/1 expressed in the high-affinity K(+) uptake deficient mutant of Saccharomyces cerevisiae and Xenopus laevis oocytes shows robust K(+) selectivity even in the presence of a large amount of NaCl as reported previously. However, No-OsHKT2;2/1-expressing yeast cells exhibited Na(+) hypersensitive growth under various concentrations of K(+) and Na(+) as the cells expressing Po-OsHKT2;2, a similar class II transporter from another salt tolerant indica rice Pokkali, when compared with the growth of cells harboring empty vector or cells expressing OsHKT2;4. The OsHKT2;4 protein expressed in Xenopus oocytes showed strong K(+) selectivity in the presence of 50 mM NaCl in comparison with No-OsHKT2;2/1 and Po-OsHKT2;2. Together with apparent plasma membrane-localization of No-OsHKT2;2/1, these results point to possibilities that No-OsHKT2;2/1 could mediate destructive Na(+) influx over K(+) uptake in Nona Bokra plants upon salinity stress, and that a predominant physiological function of No-OsHKT2;2/1 might be the acquisition of Na(+) and K(+) in K(+)-limited environments.
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Affiliation(s)
- Kei Suzuki
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano, 386-8567, Japan
| | - Alex Costa
- Department of Biosciences, University of Milan, Via G. Celoria 26, 20133, Milan, Italy
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Via G. Celoria 26, 20133, Milan, Italy
| | - Hideki Nakayama
- Institute of Environmental Studies, Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Maki Katsuhara
- Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki, 710-0046, Japan
| | - Atsuhiko Shinmyo
- Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, 630-0192, Japan
| | - Tomoaki Horie
- Division of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, 3-15-1, Tokida, Ueda, Nagano, 386-8567, Japan.
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31
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Abstract
Escherichia coli and Salmonella encounter osmotic pressure variations in natural environments that include host tissues, food, soil, and water. Osmotic stress causes water to flow into or out of cells, changing their structure, physics, and chemistry in ways that perturb cell functions. E. coli and Salmonella limit osmotically induced water fluxes by accumulating and releasing electrolytes and small organic solutes, some denoted compatible solutes because they accumulate to high levels without disturbing cell functions. Osmotic upshifts inhibit membrane-based energy transduction and macromolecule synthesis while activating existing osmoregulatory systems and specifically inducing osmoregulatory genes. The osmoregulatory response depends on the availability of osmoprotectants (exogenous organic compounds that can be taken up to become compatible solutes). Without osmoprotectants, K+ accumulates with counterion glutamate, and compatible solute trehalose is synthesized. Available osmoprotectants are taken up via transporters ProP, ProU, BetT, and BetU. The resulting compatible solute accumulation attenuates the K+ glutamate response and more effectively restores cell hydration and growth. Osmotic downshifts abruptly increase turgor pressure and strain the cytoplasmic membrane. Mechanosensitive channels like MscS and MscL open to allow nonspecific solute efflux and forestall cell lysis. Research frontiers include (i) the osmoadaptive remodeling of cell structure, (ii) the mechanisms by which osmotic stress alters gene expression, (iii) the mechanisms by which transporters and channels detect and respond to osmotic pressure changes, (iv) the coordination of osmoregulatory programs and selection of available osmoprotectants, and (v) the roles played by osmoregulatory mechanisms as E. coli and Salmonella survive or thrive in their natural environments.
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32
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A structural model for facultative anion channels in an oligomeric membrane protein: the yeast TRK (K+) system. Pflugers Arch 2015; 467:2447-60. [DOI: 10.1007/s00424-015-1712-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 06/02/2015] [Accepted: 06/04/2015] [Indexed: 12/16/2022]
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33
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Zayats V, Stockner T, Pandey SK, Wörz K, Ettrich R, Ludwig J. A refined atomic scale model of the Saccharomyces cerevisiae K+-translocation protein Trk1p combined with experimental evidence confirms the role of selectivity filter glycines and other key residues. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1183-95. [DOI: 10.1016/j.bbamem.2015.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 02/04/2015] [Accepted: 02/08/2015] [Indexed: 11/25/2022]
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Crystal structure of a two-subunit TrkA octameric gating ring assembly. PLoS One 2015; 10:e0122512. [PMID: 25826626 PMCID: PMC4380455 DOI: 10.1371/journal.pone.0122512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/12/2015] [Indexed: 12/28/2022] Open
Abstract
The TM1088 locus of T. maritima codes for two proteins designated TM1088A and TM1088B, which combine to form the cytosolic portion of a putative Trk K+ transporter. We report the crystal structure of this assembly to a resolution of 3.45 Å. The high resolution crystal structures of the components of the assembly, TM1088A and TM1088B, were also determined independently to 1.50 Å and 1.55 Å, respectively. The TM1088 proteins are structurally homologous to each other and to other K+ transporter proteins, such as TrkA. These proteins form a cytosolic gating ring assembly that controls the flow of K+ ions across the membrane. TM1088 represents the first structure of a two-subunit Trk assembly. Despite the atypical genetics and chain organization of the TM1088 assembly, it shares significant structural homology and an overall quaternary organization with other single-subunit K+ gating ring assemblies. This structure provides the first structural insights into what may be an evolutionary ancestor of more modern single-subunit K+ gating ring assemblies.
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35
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Sanadhya P, Agarwal P, Khedia J, Agarwal PK. A Low-Affinity K+ Transporter AlHKT2;1 from Recretohalophyte Aeluropus lagopoides Confers Salt Tolerance in Yeast. Mol Biotechnol 2015; 57:489-98. [DOI: 10.1007/s12033-015-9842-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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36
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Model of Cation Transportation Mediated by High-Affinity Potassium Transporters (HKTs) in Higher Plants. Biol Proced Online 2015; 17:1. [PMID: 25698907 PMCID: PMC4334588 DOI: 10.1186/s12575-014-0013-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/06/2014] [Indexed: 01/18/2023] Open
Abstract
Trk/Ktr/HKT transporters probably were evolved from simple K+ channels KcsA. HKT transporters, which mediate Na+-uniport or Na+/K+-symport, maintain K+/Na+ homeostasis and increase salinity tolerance, can be classified into three subfamilies in higher plants. In this review, we systematically analyzed the characteristics of amino acids sequences and physiological functions of HKT transporters in higher plant. Furthermore, we depicted the hypothetical models of cations selection and transportation mediated by HKT transporters according to the highly conserved structure for the goal of better understanding the cations transportation processes.
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37
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Comparative analysis of kdp and ktr mutants reveals distinct roles of the potassium transporters in the model cyanobacterium Synechocystis sp. strain PCC 6803. J Bacteriol 2014; 197:676-87. [PMID: 25313394 DOI: 10.1128/jb.02276-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Photoautotrophic bacteria have developed mechanisms to maintain K(+) homeostasis under conditions of changing ionic concentrations in the environment. Synechocystis sp. strain PCC 6803 contains genes encoding a well-characterized Ktr-type K(+) uptake transporter (Ktr) and a putative ATP-dependent transporter specific for K(+) (Kdp). The contributions of each of these K(+) transport systems to cellular K(+) homeostasis have not yet been defined conclusively. To verify the functionality of Kdp, kdp genes were expressed in Escherichia coli, where Kdp conferred K(+) uptake, albeit with lower rates than were conferred by Ktr. An on-chip microfluidic device enabled monitoring of the biphasic initial volume recovery of single Synechocystis cells after hyperosmotic shock. Here, Ktr functioned as the primary K(+) uptake system during the first recovery phase, whereas Kdp did not contribute significantly. The expression of the kdp operon in Synechocystis was induced by extracellular K(+) depletion. Correspondingly, Kdp-mediated K(+) uptake supported Synechocystis cell growth with trace amounts of external potassium. This induction of kdp expression depended on two adjacent genes, hik20 and rre19, encoding a putative two-component system. The circadian expression of kdp and ktr peaked at subjective dawn, which may support the acquisition of K(+) required for the regular diurnal photosynthetic metabolism. These results indicate that Kdp contributes to the maintenance of a basal intracellular K(+) concentration under conditions of limited K(+) in natural environments, whereas Ktr mediates fast potassium movements in the presence of greater K(+) availability. Through their distinct activities, both Ktr and Kdp coordinate the responses of Synechocystis to changes in K(+) levels under fluctuating environmental conditions.
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38
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Levin EJ, Zhou M. Recent progress on the structure and function of the TrkH/KtrB ion channel. Curr Opin Struct Biol 2014; 27:95-101. [PMID: 25011047 DOI: 10.1016/j.sbi.2014.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
Members of the Superfamily of K(+) Transporters (SKT) are integral membrane proteins that mediate the uptake of ions into non-animal cells. Although these proteins are homologous to the well-characterized K(+) channel family, relatively little was known about their transport and gating mechanisms until the recent determination of crystal structures for two SKT proteins, TrkH and KtrB. These structures reveal that the SKT proteins are channels, containing a flexible loop in the middle of the permeation pathway that may act as a gate. Two different conformational changes have been observed for the associated gating rings, suggesting different mechanisms of regulation by the binding of nucleotides.
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Affiliation(s)
- Elena J Levin
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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39
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Hamamoto S, Uozumi N. Organelle-localized potassium transport systems in plants. JOURNAL OF PLANT PHYSIOLOGY 2014; 171:743-7. [PMID: 24810770 DOI: 10.1016/j.jplph.2013.09.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 09/06/2013] [Accepted: 09/06/2013] [Indexed: 05/03/2023]
Abstract
Some intracellular organelles found in eukaryotes such as plants have arisen through the endocytotic engulfment of prokaryotic cells. This accounts for the presence of plant membrane intrinsic proteins that have homologs in prokaryotic cells. Other organelles, such as those of the endomembrane system, are thought to have evolved through infolding of the plasma membrane. Acquisition of intracellular components (organelles) in the cells supplied additional functions for survival in various natural environments. The organelles are surrounded by biological membranes, which contain membrane-embedded K(+) transport systems allowing K(+) to move across the membrane. K(+) transport systems in plant organelles act coordinately with the plasma membrane intrinsic K(+) transport systems to maintain cytosolic K(+) concentrations. Since it is sometimes difficult to perform direct studies of organellar membrane proteins in plant cells, heterologous expression in yeast and Escherichia coli has been used to elucidate the function of plant vacuole K(+) channels and other membrane transporters. The vacuole is the largest organelle in plant cells; it has an important task in the K(+) homeostasis of the cytoplasm. The initial electrophysiological measurements of K(+) transport have categorized three classes of plant vacuolar cation channels, and since then molecular cloning approaches have led to the isolation of genes for a number of K(+) transport systems. Plants contain chloroplasts, derived from photoautotrophic cyanobacteria. A novel K(+) transport system has been isolated from cyanobacteria, which may add to our understanding of K(+) flux across the thylakoid membrane and the inner membrane of the chloroplast. This chapter will provide an overview of recent findings regarding plant organellar K(+) transport proteins.
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Affiliation(s)
- Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
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40
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Sato Y, Nanatani K, Hamamoto S, Shimizu M, Takahashi M, Tabuchi-Kobayashi M, Mizutani A, Schroeder JI, Souma S, Uozumi N. Defining membrane spanning domains and crucial membrane-localized acidic amino acid residues for K+ transport of a Kup/HAK/KT-type Escherichia coli potassium transporter. ACTA ACUST UNITED AC 2014; 155:315-23. [DOI: 10.1093/jb/mvu007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Herrera R, Álvarez MC, Gelis S, Kodedová M, Sychrová H, Kschischo M, Ramos J. Role of Saccharomyces cerevisiae Trk1 in stabilization of intracellular potassium content upon changes in external potassium levels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:127-33. [DOI: 10.1016/j.bbamem.2013.08.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 11/30/2022]
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Yamaguchi T, Hamamoto S, Uozumi N. Sodium transport system in plant cells. FRONTIERS IN PLANT SCIENCE 2013; 4:410. [PMID: 24146669 PMCID: PMC3797977 DOI: 10.3389/fpls.2013.00410] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 09/27/2013] [Indexed: 05/18/2023]
Abstract
Since sodium, Na, is a non-essential element for the plant growth, the molecular mechanism of Na(+) transport system in plants has remained elusive for the last two decades. The accumulation of Na(+) in soil through irrigation for sustainable agricultural crop production, particularly in arid land, and by changes in environmental and climate conditions leads to the buildup of toxic level of salts in the soil. Since the latter half of the twentieth century, extensive molecular research has identified several classes of Na(+) transporters that play major roles in the alleviation of ionic stress by excluding toxic Na(+) from the cytosol or preventing Na(+) transport to the photosynthetic organs, and also in osmotic stress by modulating intra/extracellular osmotic balance. In this review, we summarize the current knowledge of three major Na(+) transporters, namely NHX, SOS1, and HKT transporters, including recently revealed characteristics of these transporters.
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Affiliation(s)
- Toshio Yamaguchi
- Department of Microbiology, Faculty of Pharmacy, Niigata University of Pharmacy and Applied Life SciencesNiigata, Japan
| | - Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku UniversitySendai, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku UniversitySendai, Japan
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HKT transporters--state of the art. Int J Mol Sci 2013; 14:20359-85. [PMID: 24129173 PMCID: PMC3821619 DOI: 10.3390/ijms141020359] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 08/15/2013] [Accepted: 09/18/2013] [Indexed: 12/18/2022] Open
Abstract
The increase in soil salinity poses a serious threat to agricultural yields. Under salinity stress, several Na⁺ transporters play an essential role in Na⁺ tolerance in plants. Amongst all Na+ transporters, HKT has been shown to have a crucial role in both mono and dicotyledonous plants in the tolerance to salinity stress. Here we present an overview of the physiological role of HKT transporters in plant Na⁺ homeostasis. HKT regulation and amino acids important to the correct function of HKT transporters are reviewed. The functions of the most recently characterized HKT members from both HKT1 and HKT2 subfamilies are also discussed. Topics that still need to be studied in future research (e.g., HKT regulation) as well as research suggestions (e.g., generation of HKT mutants) are addressed.
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Abstract
Staphylococcus aureus is a hardy organism that can survive high-salt conditions better than many other bacteria. This characteristic is thought to help S. aureus survive in the nares and on the skin of the human host and is used to selectively propagate and identify Staphylococcus species. However, the mechanism that allows S. aureus to tolerate such high-salt conditions is not well understood. A recent study in mBio by A. Price-Whelan et al. [mBio 4(4):e00407-13, 2013, doi:10.1128/mBio.00407-13] highlights the importance of potassium uptake in this process. This commentary provides a perspective of the study by Price-Whelan et al. as well as other recently reported work on potassium uptake and transport systems in S. aureus.
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Asins MJ, Villalta I, Aly MM, Olías R, Alvarez DE Morales P, Huertas R, Li J, Jaime-Pérez N, Haro R, Raga V, Carbonell EA, Belver A. Two closely linked tomato HKT coding genes are positional candidates for the major tomato QTL involved in Na+ /K+ homeostasis. PLANT, CELL & ENVIRONMENT 2013; 36:1171-91. [PMID: 23216099 DOI: 10.1111/pce.12051] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 11/28/2012] [Indexed: 05/18/2023]
Abstract
The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na(+) ] and [K(+) ] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na(+) -selective class I-HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single-nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near-isogenic lines (NILs): 157-14 (double homozygote for the cheesmaniae alleles) and 157-17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157-14 in comparison with 157-17. A significant difference between NILs was also found for [K(+) ] and the [Na(+) ]/[K(+) ] ratio in leaf and stem but not for [Na(+) ] arising a disagreement with the corresponding RIL population. Their association with leaf [Na(+) ] and salt tolerance in tomato is also discussed.
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Affiliation(s)
- Maria José Asins
- Plant Protection and Biotechnology Center, Instituto Valenciano de Investigaciones Agrarias (IVIA), E46113, Valencia, Spain.
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The structure of the KtrAB potassium transporter. Nature 2013; 496:323-8. [PMID: 23598340 DOI: 10.1038/nature12055] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 03/05/2013] [Indexed: 12/23/2022]
Abstract
In bacteria, archaea, fungi and plants the Trk, Ktr and HKT ion transporters are key components of osmotic regulation, pH homeostasis and resistance to drought and high salinity. These ion transporters are functionally diverse: they can function as Na(+) or K(+) channels and possibly as cation/K(+) symporters. They are closely related to potassium channels both at the level of the membrane protein and at the level of the cytosolic regulatory domains. Here we describe the crystal structure of a Ktr K(+) transporter, the KtrAB complex from Bacillus subtilis. The structure shows the dimeric membrane protein KtrB assembled with a cytosolic octameric KtrA ring bound to ATP, an activating ligand. A comparison between the structure of KtrAB-ATP and the structures of the isolated full-length KtrA protein with ATP or ADP reveals a ligand-dependent conformational change in the octameric ring, raising new ideas about the mechanism of activation in these transporters.
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Abstract
Recent research suggests that in addition to their role as soluble electron carriers, pyridine nucleotides [NAD(P)(H)] also regulate ion transport mechanisms. This mode of regulation seems to have been conserved through evolution. Several bacterial ion-transporting proteins or their auxiliary subunits possess nucleotide-binding domains. In eukaryotes, the Kv1 and Kv4 channels interact with pyridine nucleotide-binding β-subunits that belong to the aldo-keto reductase superfamily. Binding of NADP(+) to Kvβ removes N-type inactivation of Kv currents, whereas NADPH stabilizes channel inactivation. Pyridine nucleotides also regulate Slo channels by interacting with their cytosolic regulator of potassium conductance domains that show high sequence homology to the bacterial TrkA family of K(+) transporters. These nucleotides also have been shown to modify the activity of the plasma membrane K(ATP) channels, the cystic fibrosis transmembrane conductance regulator, the transient receptor potential M2 channel, and the intracellular ryanodine receptor calcium release channels. In addition, pyridine nucleotides also modulate the voltage-gated sodium channel by supporting the activity of its ancillary subunit-the glycerol-3-phosphate dehydrogenase-like protein. Moreover, the NADP(+) metabolite, NAADP(+), regulates intracellular calcium homeostasis via the 2-pore channel, ryanodine receptor, or transient receptor potential M2 channels. Regulation of ion channels by pyridine nucleotides may be required for integrating cell ion transport to energetics and for sensing oxygen levels or metabolite availability. This mechanism also may be an important component of hypoxic pulmonary vasoconstriction, memory, and circadian rhythms, and disruption of this regulatory axis may be linked to dysregulation of calcium homeostasis and cardiac arrhythmias.
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Affiliation(s)
- Peter J Kilfoil
- Diabetes Obesity Center, University of Louisville, Louisville, KY 40202, USA
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Coordination of K+ transporters in neurospora: TRK1 is scarce and constitutive, while HAK1 is abundant and highly regulated. EUKARYOTIC CELL 2013; 12:684-96. [PMID: 23475706 DOI: 10.1128/ec.00017-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fungi, plants, and bacteria accumulate potassium via two distinct molecular machines not directly coupled to ATP hydrolysis. The first, designated TRK, HKT, or KTR, has eight transmembrane helices and is folded like known potassium channels, while the second, designated HAK, KT, or KUP, has 12 transmembrane helices and resembles MFS class proteins. One of each type functions in the model organism Neurospora crassa, where both are readily accessible for biochemical, genetic, and electrophysiological characterization. We have now determined the operating balance between Trk1p and Hak1p under several important conditions, including potassium limitation and carbon starvation. Growth measurements, epitope tagging, and quantitative Western blotting have shown the gene HAK1 to be much more highly regulated than is TRK1. This conclusion follows from three experimental results: (i) Trk1p is expressed constitutively but at low levels, and it is barely sensitive to extracellular [K(+)] and/or the coexpression of HAK1; (ii) Hak1p is abundant but is markedly depressed by elevated extracellular concentrations of K(+) and by coexpression of TRK1; and (iii) Carbon starvation slowly enhances Hak1p expression and depresses Trk1p expression, yielding steady-state Hak1p:Trk1p ratios of ∼500:1, viz., 10- to 50-fold larger than that in K(+)- and carbon-replete cells. Additionally, it appears that both potassium transporters can adjust kinetically to sustained low-K(+) stress by means of progressively increasing transporter affinity for extracellular K(+). The underlying observations are (iv) that K(+) influx via Trk1p remains nearly constant at ∼9 mM/h when extracellular K(+) is progressively depleted below 0.05 mM and (v) that K(+) influx via Hak1p remains at ∼3 mM/h when extracellular K(+) is depleted below 0.1 mM.
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Negrão S, Almadanim MC, Pires IS, Abreu IA, Maroco J, Courtois B, Gregorio GB, McNally KL, Oliveira MM. New allelic variants found in key rice salt-tolerance genes: an association study. PLANT BIOTECHNOLOGY JOURNAL 2013; 11:87-100. [PMID: 23116435 DOI: 10.1111/pbi.12010] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Revised: 09/17/2012] [Accepted: 09/19/2012] [Indexed: 05/18/2023]
Abstract
Salt stress is a complex physiological trait affecting plants by limiting growth and productivity. Rice, one of the most important food crops, is rated as salt-sensitive. High-throughput screening methods are required to exploit novel sources of genetic variation in rice and further improve salinity tolerance in breeding programmes. To search for genotypic differences related to salt stress, we genotyped 392 rice accessions by EcoTILLING. We targeted five key salt-related genes involved in mechanisms such as Na(+) /K(+) ratio equilibrium, signalling cascade and stress protection, and we found 40 new allelic variants in coding sequences. By performing association analyses using both general and mixed linear models, we identified 11 significant SNPs related to salinity. We further evaluated the putative consequences of these SNPs at the protein level using bioinformatic tools. Amongst the five nonsynonymous SNPs significantly associated with salt-stress traits, we found a T67K mutation that may cause the destabilization of one transmembrane domain in OsHKT1;5, and a P140A alteration that significantly increases the probability of OsHKT1;5 phosphorylation. The K24E mutation can putatively affect SalT interaction with other proteins thus impacting its function. Our results have uncovered allelic variants affecting salinity tolerance that may be important in breeding.
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Affiliation(s)
- Sónia Negrão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal; iBET, Oeiras, Portugal
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50
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Oomen RJFJ, Benito B, Sentenac H, Rodríguez-Navarro A, Talón M, Véry AA, Domingo C. HKT2;2/1, a K⁺-permeable transporter identified in a salt-tolerant rice cultivar through surveys of natural genetic polymorphism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 71:750-62. [PMID: 22530609 DOI: 10.1111/j.1365-313x.2012.05031.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We have investigated OsHKT2;1 natural variation in a collection of 49 cultivars with different levels of salt tolerance and geographical origins. The effect of identified polymorphism on OsHKT2;1 activity was analysed through heterologous expression of variants in Xenopus oocytes. OsHKT2;1 appeared to be a highly conserved protein with only five possible amino acid substitutions that have no substantial effect on functional properties. Our study, however, also identified a new HKT isoform, No-OsHKT2;2/1 in Nona Bokra, a highly salt-tolerant cultivar. No-OsHKT2;2/1 probably originated from a deletion in chromosome 6, producing a chimeric gene. Its 5' region corresponds to that of OsHKT2;2, whose full-length sequence is not present in Nipponbare but has been identified in Pokkali, a salt-tolerant rice cultivar. Its 3' region corresponds to that of OsHKT2;1. No-OsHKT2;2/1 is essentially expressed in roots and displays a significant level of expression at high Na⁺ concentrations, in contrast to OsHKT2;1. Expressed in Xenopus oocytes or in Saccharomyces cerevisiae, No-OsHKT2;2/1 exhibited a strong permeability to Na⁺ and K⁺, even at high external Na⁺ concentrations, like OsHKT2;2, and in contrast to OsHKT2;1. Our results suggest that No-OsHKT2;2/1 can contribute to Nona Bokra salt tolerance by enabling root K⁺ uptake under saline conditions.
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Affiliation(s)
- Ronald J F J Oomen
- Biochimie et Physiologie Moléculaire des Plantes, Institut de Biologie Intégrative des Plantes, UMR 5004 CNRS/UMR 0386 INRA/Montpellier SupAgro/Université Montpellier 2, 34060 Montpellier Cedex 2, France
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