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Quintero-Yanes A, Léger L, Collignon M, Mignon J, Mayard A, Michaux C, Hallez R. Regulation of potassium uptake in Caulobacter crescentus. J Bacteriol 2024; 206:e0010724. [PMID: 39133005 PMCID: PMC11411941 DOI: 10.1128/jb.00107-24] [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: 03/09/2024] [Accepted: 07/13/2024] [Indexed: 08/13/2024] Open
Abstract
Potassium (K+) is an essential physiological element determining membrane potential, intracellular pH, osmotic/turgor pressure, and protein synthesis in cells. Here, we describe the regulation of potassium uptake systems in the oligotrophic α-proteobacterium Caulobacter crescentus known as a model for asymmetric cell division. We show that C. crescentus can grow in concentrations from the micromolar to the millimolar range by mainly using two K+ transporters to maintain potassium homeostasis, the low-affinity Kup and the high-affinity Kdp uptake systems. When K+ is not limiting, we found that the kup gene is essential while kdp inactivation does not impact the growth. In contrast, kdp becomes critical but not essential and kup dispensable for growth in K+-limited environments. However, in the absence of kdp, mutations in kup were selected to improve growth in K+-depleted conditions, likely by increasing the affinity of Kup for K+. In addition, mutations in the KdpDE two-component system, which regulates kdpABCDE expression, suggest that the inner membrane sensor regulatory component KdpD mainly works as a phosphatase to limit the growth when cells reach late exponential phase. Our data therefore suggest that KdpE is phosphorylated by another non-cognate histidine kinase. On top of this, we determined the KdpE-dependent and independent K+ transcriptome. Together, our work illustrates how an oligotrophic bacterium responds to fluctuation in K+ availability.IMPORTANCEPotassium (K+) is a key metal ion involved in many essential cellular processes. Here, we show that the oligotroph Caulobacter crescentus can support growth at micromolar concentrations of K+ by mainly using two K+ uptake systems, the low-affinity Kup and the high-affinity Kdp. Using genome-wide approaches, we also determined the entire set of genes required for C. crescentus to survive at low K+ concentration as well as the full K+-dependent regulon. Finally, we found that the transcriptional regulation mediated by the KdpDE two-component system is unconventional since unlike Escherichia coli, the inner membrane sensor regulatory component KdpD seems to work rather as a phosphatase on the phosphorylated response regulator KdpE~P.
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Affiliation(s)
- Alex Quintero-Yanes
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Loïc Léger
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Madeline Collignon
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Julien Mignon
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, Namur Institute of Structured Matter (NISM), Namur Research Institute for Life Sciences (NARILIS), Universite de Namur, Namur, Belgium
| | - Aurélie Mayard
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
| | - Catherine Michaux
- Laboratoire de Chimie Physique des Biomolécules, UCPTS, Namur Institute of Structured Matter (NISM), Namur Research Institute for Life Sciences (NARILIS), Universite de Namur, Namur, Belgium
| | - Régis Hallez
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), Universite de Namur, Namur, Belgium
- WEL Research Institute, University of Namur, Namur, Belgium
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2
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Weigle AT, Shukla D. The Arabidopsis AtSWEET13 transporter discriminates sugars by selective facial and positional substrate recognition. Commun Biol 2024; 7:764. [PMID: 38914639 PMCID: PMC11196581 DOI: 10.1038/s42003-024-06291-6] [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: 10/26/2022] [Accepted: 05/03/2024] [Indexed: 06/26/2024] Open
Abstract
Transporters are targeted by endogenous metabolites and exogenous molecules to reach cellular destinations, but it is generally not understood how different substrate classes exploit the same transporter's mechanism. Any disclosure of plasticity in transporter mechanism when treated with different substrates becomes critical for developing general selectivity principles in membrane transport catalysis. Using extensive molecular dynamics simulations with an enhanced sampling approach, we select the Arabidopsis sugar transporter AtSWEET13 as a model system to identify the basis for glucose versus sucrose molecular recognition and transport. Here we find that AtSWEET13 chemical selectivity originates from a conserved substrate facial selectivity demonstrated when committing alternate access, despite mono-/di-saccharides experiencing differing degrees of conformational and positional freedom throughout other stages of transport. However, substrate interactions with structural hallmarks associated with known functional annotations can help reinforce selective preferences in molecular transport.
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Affiliation(s)
- Austin T Weigle
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Diwakar Shukla
- Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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3
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Chiang WT, Chang YK, Hui WH, Chang SW, Liao CY, Chang YC, Chen CJ, Wang WC, Lai CC, Wang CH, Luo SY, Huang YP, Chou SH, Horng TL, Hou MH, Muench SP, Chen RS, Tsai MD, Hu NJ. Structural basis and synergism of ATP and Na + activation in bacterial K + uptake system KtrAB. Nat Commun 2024; 15:3850. [PMID: 38719864 PMCID: PMC11078986 DOI: 10.1038/s41467-024-48057-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 04/17/2024] [Indexed: 05/12/2024] Open
Abstract
The K+ uptake system KtrAB is essential for bacterial survival in low K+ environments. The activity of KtrAB is regulated by nucleotides and Na+. Previous studies proposed a putative gating mechanism of KtrB regulated by KtrA upon binding to ATP or ADP. However, how Na+ activates KtrAB and the Na+ binding site remain unknown. Here we present the cryo-EM structures of ATP- and ADP-bound KtrAB from Bacillus subtilis (BsKtrAB) both solved at 2.8 Å. A cryo-EM density at the intra-dimer interface of ATP-KtrA was identified as Na+, as supported by X-ray crystallography and ICP-MS. Thermostability assays and functional studies demonstrated that Na+ binding stabilizes the ATP-bound BsKtrAB complex and enhances its K+ flux activity. Comparing ATP- and ADP-BsKtrAB structures suggests that BsKtrB Arg417 and Phe91 serve as a channel gate. The synergism of ATP and Na+ in activating BsKtrAB is likely applicable to Na+-activated K+ channels in central nervous system.
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Affiliation(s)
- Wesley Tien Chiang
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Yao-Kai Chang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Wei-Han Hui
- Department of Civil Engineering, National Taiwan University, Taipei, 106319, Taiwan
| | - Shu-Wei Chang
- Department of Civil Engineering, National Taiwan University, Taipei, 106319, Taiwan
- Department of Biomedical Engineering, National Taiwan University, Taipei, 10663, Taiwan
| | - Chen-Yi Liao
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Yi-Chuan Chang
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Chun-Jung Chen
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, 30092, Taiwan
| | - Wei-Chen Wang
- Institute of Molecular Biology, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Chien-Chen Lai
- Institute of Molecular Biology, National Chung Hsing University, Taichung, 402202, Taiwan
- Graduate Institute of Chinese Medical Science, China Medical University, Taichung, 406040, Taiwan
| | - Chun-Hsiung Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Siou-Ying Luo
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Ya-Ping Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan
| | - Shan-Ho Chou
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Tzyy-Leng Horng
- Department of Applied Mathematics, Feng Chia University, Taichung, 407102, Taiwan
| | - Ming-Hon Hou
- Institute of Genomics and Bioinformatics, National Chung Hsing University, Taichung, 402202, Taiwan
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences and the Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Ren-Shiang Chen
- Department of Life Science, Tunghai University, Taichung, 407224, Taiwan
| | - Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, 115201, Taiwan.
- Institute of Biochemical Sciences, National Taiwan University, Taipei, 106319, Taiwan.
| | - Nien-Jen Hu
- Graduate Institute of Biochemistry, National Chung Hsing University, Taichung, 402202, Taiwan.
- Ph.D Program in Translational Medicine, National Chung Hsing University, Taichung, 402202, Taiwan.
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4
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Wang X, Shen X, Qu Y, Zhang H, Wang C, Yang F, Shen H. Structural insights into ion selectivity and transport mechanisms of Oryza sativa HKT2;1 and HKT2;2/1 transporters. NATURE PLANTS 2024; 10:633-644. [PMID: 38570642 DOI: 10.1038/s41477-024-01665-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 03/06/2024] [Indexed: 04/05/2024]
Abstract
Plant high-affinity K+ transporters (HKTs) play a pivotal role in maintaining the balance of Na+ and K+ ions in plants, thereby influencing plant growth under K+-depleted conditions and enhancing tolerance to salinity stress. Here we report the cryo-electron microscopy structures of Oryza sativa HKT2;1 and HKT2;2/1 at overall resolutions of 2.5 Å and 2.3 Å, respectively. Both transporters adopt a dimeric assembly, with each protomer enclosing an ion permeation pathway. Comparison between the selectivity filters of the two transporters reveals the critical roles of Ser88/Gly88 and Val243/Gly243 in determining ion selectivity. A constriction site along the ion permeation pathway is identified, consisting of Glu114, Asn273, Pro392, Pro393, Arg525, Lys517 and the carboxy-terminal Trp530 from the neighbouring protomer. The linker between domains II and III adopts a stable loop structure oriented towards the constriction site, potentially participating in the gating process. Electrophysiological recordings, yeast complementation assays and molecular dynamics simulations corroborate the functional importance of these structural features. Our findings provide crucial insights into the ion selectivity and transport mechanisms of plant HKTs, offering valuable structural templates for developing new salinity-tolerant cultivars and strategies to increase crop yields.
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Affiliation(s)
- Xiaohui Wang
- Zhejiang Key Laboratory of Structural Biology, School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, China
| | - Xiaoshuai Shen
- Zhejiang Key Laboratory of Structural Biology, School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, China
| | - Yannan Qu
- Zhejiang Key Laboratory of Structural Biology, School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, China
| | - Heng Zhang
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Chu Wang
- Zhejiang Key Laboratory of Structural Biology, School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, China
| | - Fan Yang
- Department of Biophysics and Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China.
| | - Huaizong Shen
- Zhejiang Key Laboratory of Structural Biology, School of Life Sciences, Westlake University, Hangzhou, China.
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China.
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, China.
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5
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Wang J, Luo Y, Ye F, Ding ZJ, Zheng SJ, Qiao S, Wang Y, Guo J, Yang W, Su N. Structures and ion transport mechanisms of plant high-affinity potassium transporters. MOLECULAR PLANT 2024; 17:409-422. [PMID: 38335958 DOI: 10.1016/j.molp.2024.01.007] [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: 12/01/2023] [Revised: 01/11/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024]
Abstract
Plant high-affinity K+ transporters (HKTs) mediate Na+ and K+ uptake, maintain Na+/K+ homeostasis, and therefore play crucial roles in plant salt tolerance. In this study, we present cryoelectron microscopy structures of HKTs from two classes, class I HKT1;1 from Arabidopsis thaliana (AtHKT1;1) and class II HKT2;1 from Triticum aestivum (TaHKT2;1), in both Na+- and K+-bound states at 2.6- to 3.0-Å resolutions. Both AtHKT1;1 and TaHKT2;1 function as homodimers. Each HKT subunit consists of four tandem domain units (D1-D4) with a repeated K+-channel-like M-P-M topology. In each subunit, D1-D4 assemble into an ion conduction pore with a pseudo-four-fold symmetry. Although both TaHKT2;1 and AtHKT1;1 have only one putative Na+ ion bound in the selectivity filter with a similar coordination pattern, the two HKTs display different K+ binding modes in the filter. TaHKT2;1 has three K+ ions bound in the selectivity filter, but AtHKT1;1 has only two K+ ions bound in the filter, which has a narrowed external entrance due to the presence of a Ser residue in the first filter motif. These structures, along with computational, mutational, and electrophysiological analyses, enable us to pinpoint key residues that are critical for the ion selectivity of HKTs. The findings provide new insights into the ion selectivity and ion transport mechanisms of plant HKTs and improve our understanding about how HKTs mediate plant salt tolerance and enhance crop growth.
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Affiliation(s)
- Jiangqin Wang
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, China
| | - Yanping Luo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Fan Ye
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Zhong Jie Ding
- State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shao Jian Zheng
- State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shuai Qiao
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, China
| | - Yong Wang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jiangtao Guo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; Nanhu Brain-computer Interface Institute, Hangzhou, Zhejiang 311100, China.
| | - Wei Yang
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| | - Nannan Su
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, China.
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Gámez-Arjona F, Park HJ, García E, Aman R, Villalta I, Raddatz N, Carranco R, Ali A, Ali Z, Zareen S, De Luca A, Leidi EO, Daniel-Mozo M, Xu ZY, Albert A, Kim WY, Pardo JM, Sánchez-Rodriguez C, Yun DJ, Quintero FJ. Inverse regulation of SOS1 and HKT1 protein localization and stability by SOS3/CBL4 in Arabidopsis thaliana. Proc Natl Acad Sci U S A 2024; 121:e2320657121. [PMID: 38386704 PMCID: PMC10907282 DOI: 10.1073/pnas.2320657121] [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: 12/04/2023] [Accepted: 01/12/2024] [Indexed: 02/24/2024] Open
Abstract
To control net sodium (Na+) uptake, Arabidopsis plants utilize the plasma membrane (PM) Na+/H+ antiporter SOS1 to achieve Na+ efflux at the root and Na+ loading into the xylem, and the channel-like HKT1;1 protein that mediates the reverse flux of Na+ unloading off the xylem. Together, these opposing transport systems govern the partition of Na+ within the plant yet they must be finely co-regulated to prevent a futile cycle of xylem loading and unloading. Here, we show that the Arabidopsis SOS3 protein acts as the molecular switch governing these Na+ fluxes by favoring the recruitment of SOS1 to the PM and its subsequent activation by the SOS2/SOS3 kinase complex under salt stress, while commanding HKT1;1 protein degradation upon acute sodic stress. SOS3 achieves this role by direct and SOS2-independent binding to previously unrecognized functional domains of SOS1 and HKT1;1. These results indicate that roots first retain moderate amounts of salts to facilitate osmoregulation, yet when sodicity exceeds a set point, SOS3-dependent HKT1;1 degradation switches the balance toward Na+ export out of the root. Thus, SOS3 functionally links and co-regulates the two major Na+ transport systems operating in vascular plants controlling plant tolerance to salinity.
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Affiliation(s)
- Francisco Gámez-Arjona
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
- Department of Biology, ETH Zurich, Zurich8092, Switzerland
| | - Hee Jin Park
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
- Department of Biological Sciences, Chonnam National University, Gwangju61186, Korea
| | - Elena García
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Rashid Aman
- Laboratory for Genome Engineering and Synthetic Biology, King Abdullah University of Science and Technology, Thuwal23955-6900, Saudi Arabia
| | - Irene Villalta
- Institut de Recherche sur la Biologie de l’Insecte, Université de Tours, Tours37200, France
| | - Natalia Raddatz
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Raul Carranco
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Akhtar Ali
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
| | - Zahir Ali
- Laboratory for Genome Engineering and Synthetic Biology, King Abdullah University of Science and Technology, Thuwal23955-6900, Saudi Arabia
| | - Shah Zareen
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
| | - Anna De Luca
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Eduardo O. Leidi
- Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Cientificas, Seville41012, Spain
| | - Miguel Daniel-Mozo
- Instituto de Química Física Blas Cabrera, Consejo Superior de Investigaciones Científicas, Madrid28006, Spain
| | - Zheng-Yi Xu
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun130024, China
| | - Armando Albert
- Instituto de Química Física Blas Cabrera, Consejo Superior de Investigaciones Científicas, Madrid28006, Spain
| | - Woe-Yeon Kim
- Division of Applied Life Science (BK21 Program), Research Institute of Life Sciences, Gyeongsang National University, Jinju660-701, South Korea
| | - Jose M. Pardo
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Clara Sánchez-Rodriguez
- Department of Biology, ETH Zurich, Zurich8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid–Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (CSIC), Pozuelo de Alarcón28223, Spain
| | - Dae-Jin Yun
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
| | - Francisco J. Quintero
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
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Liang KK. On the crucial features of a single‐file transport model for ion channels. J CHIN CHEM SOC-TAIP 2023. [DOI: 10.1002/jccs.202200517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Kuo Kan Liang
- Department of Physics National Taiwan University Taipei Taiwan
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8
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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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9
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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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10
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Gyimesi G, Hediger MA. Systematic in silico discovery of novel solute carrier-like proteins from proteomes. PLoS One 2022; 17:e0271062. [PMID: 35901096 PMCID: PMC9333335 DOI: 10.1371/journal.pone.0271062] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 06/22/2022] [Indexed: 12/26/2022] Open
Abstract
Solute carrier (SLC) proteins represent the largest superfamily of transmembrane transporters. While many of them play key biological roles, their systematic analysis has been hampered by their functional and structural heterogeneity. Based on available nomenclature systems, we hypothesized that many as yet unidentified SLC transporters exist in the human genome, which await further systematic analysis. Here, we present criteria for defining "SLC-likeness" to curate a set of "SLC-like" protein families from the Transporter Classification Database (TCDB) and Protein families (Pfam) databases. Computational sequence similarity searches surprisingly identified ~120 more proteins in human with potential SLC-like properties compared to previous annotations. Interestingly, several of these have documented transport activity in the scientific literature. To complete the overview of the "SLC-ome", we present an algorithm to classify SLC-like proteins into protein families, investigating their known functions and evolutionary relationships to similar proteins from 6 other clinically relevant experimental organisms, and pinpoint structural orphans. We envision that our work will serve as a stepping stone for future studies of the biological function and the identification of the natural substrates of the many under-explored SLC transporters, as well as for the development of new therapeutic applications, including strategies for personalized medicine and drug delivery.
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Affiliation(s)
- Gergely Gyimesi
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department for BioMedical Research, Inselspital, University of Bern, Bern, Switzerland
- * E-mail: (GG); (MAH)
| | - Matthias A. Hediger
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension and Department for BioMedical Research, Inselspital, University of Bern, Bern, Switzerland
- * E-mail: (GG); (MAH)
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11
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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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12
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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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13
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Chan MC, Selvam B, Young HJ, Procko E, Shukla D. The substrate import mechanism of the human serotonin transporter. Biophys J 2022; 121:715-730. [PMID: 35114149 PMCID: PMC8943754 DOI: 10.1016/j.bpj.2022.01.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/18/2021] [Accepted: 01/25/2022] [Indexed: 11/17/2022] Open
Abstract
The serotonin transporter (SERT) initiates the reuptake of extracellular serotonin in the synapse to terminate neurotransmission. The cryogenic electron microscopy structures of SERT bound to ibogaine and the physiological substrate serotonin resolved in different states have provided a glimpse of the functional conformations at atomistic resolution. However, the conformational dynamics and structural transitions to intermediate states are not fully understood. Furthermore, the molecular basis of how serotonin is recognized and transported remains unclear. In this study, we performed unbiased microsecond-long simulations of the human SERT to investigate the structural dynamics to various intermediate states and elucidated the complete substrate import pathway. Using Markov state models, we characterized a sequential order of conformational-driven ion-coupled substrate binding and transport events and calculated the free energy barriers of conformation transitions associated with the import mechanism. We find that the transition from the occluded to inward-facing state is the rate-limiting step for substrate import and that the substrate decreases the free energy barriers to achieve the inward-facing state. Our study provides insights on the molecular basis of dynamics-driven ion-substrate recognition and transport of SERT that can serve as a model for other closely related neurotransmitter transporters.
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Affiliation(s)
- Matthew C Chan
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Balaji Selvam
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Heather J Young
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Erik Procko
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois; Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois; National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, Illinois; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois; NIH Center for Macromolecular Modeling and Bioinformatics, University of Illinois at Urbana-Champaign, Urbana, Illinois.
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14
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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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15
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Saradadevi GP, Das D, Mangrauthia SK, Mohapatra S, Chikkaputtaiah C, Roorkiwal M, Solanki M, Sundaram RM, Chirravuri NN, Sakhare AS, Kota S, Varshney RK, Mohannath G. Genetic, Epigenetic, Genomic and Microbial Approaches to Enhance Salt Tolerance of Plants: A Comprehensive Review. BIOLOGY 2021; 10:biology10121255. [PMID: 34943170 PMCID: PMC8698797 DOI: 10.3390/biology10121255] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 12/17/2022]
Abstract
Simple Summary Globally, soil salinity, which refers to salt-affected soils, is increasing due to various environmental factors and human activities. Soil salinity poses one of the most serious challenges in the field of agriculture as it significantly reduces the growth and yield of crop plants, both quantitatively and qualitatively. Over the last few decades, several studies have been carried out to understand plant biology in response to soil salinity stress with a major emphasis on genetic and other hereditary components. Based on the outcome of these studies, several approaches are being followed to enhance plants’ ability to tolerate salt stress while still maintaining reasonable levels of crop yields. In this manuscript, we comprehensively list and discuss various biological approaches being followed and, based on the recent advances in the field of molecular biology, we propose some new approaches to improve salinity tolerance of crop plants. The global scientific community can make use of this information for the betterment of crop plants. This review also highlights the importance of maintaining global soil health to prevent several crop plant losses. Abstract Globally, soil salinity has been on the rise owing to various factors that are both human and environmental. The abiotic stress caused by soil salinity has become one of the most damaging abiotic stresses faced by crop plants, resulting in significant yield losses. Salt stress induces physiological and morphological modifications in plants as a result of significant changes in gene expression patterns and signal transduction cascades. In this comprehensive review, with a major focus on recent advances in the field of plant molecular biology, we discuss several approaches to enhance salinity tolerance in plants comprising various classical and advanced genetic and genetic engineering approaches, genomics and genome editing technologies, and plant growth-promoting rhizobacteria (PGPR)-based approaches. Furthermore, based on recent advances in the field of epigenetics, we propose novel approaches to create and exploit heritable genome-wide epigenetic variation in crop plants to enhance salinity tolerance. Specifically, we describe the concepts and the underlying principles of epigenetic recombinant inbred lines (epiRILs) and other epigenetic variants and methods to generate them. The proposed epigenetic approaches also have the potential to create additional genetic variation by modulating meiotic crossover frequency.
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Affiliation(s)
- Gargi Prasad Saradadevi
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Hyderabad 500078, India; (G.P.S.); (S.M.)
| | - Debajit Das
- Biological Sciences and Technology Division, CSIR-North East Institute of Science and Technology (CSIR-NEIST), Jorhat 785006, India; (D.D.); (C.C.)
| | - Satendra K. Mangrauthia
- ICAR-Indian Institute of Rice Research, Hyderabad 500030, India; (S.K.M.); (M.S.); (R.M.S.); (N.N.C.); (A.S.S.)
| | - Sridev Mohapatra
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Hyderabad 500078, India; (G.P.S.); (S.M.)
| | - Channakeshavaiah Chikkaputtaiah
- Biological Sciences and Technology Division, CSIR-North East Institute of Science and Technology (CSIR-NEIST), Jorhat 785006, India; (D.D.); (C.C.)
| | - Manish Roorkiwal
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad 502324, India;
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6009, Australia
| | - Manish Solanki
- ICAR-Indian Institute of Rice Research, Hyderabad 500030, India; (S.K.M.); (M.S.); (R.M.S.); (N.N.C.); (A.S.S.)
| | - Raman Meenakshi Sundaram
- ICAR-Indian Institute of Rice Research, Hyderabad 500030, India; (S.K.M.); (M.S.); (R.M.S.); (N.N.C.); (A.S.S.)
| | - Neeraja N. Chirravuri
- ICAR-Indian Institute of Rice Research, Hyderabad 500030, India; (S.K.M.); (M.S.); (R.M.S.); (N.N.C.); (A.S.S.)
| | - Akshay S. Sakhare
- ICAR-Indian Institute of Rice Research, Hyderabad 500030, India; (S.K.M.); (M.S.); (R.M.S.); (N.N.C.); (A.S.S.)
| | - Suneetha Kota
- ICAR-Indian Institute of Rice Research, Hyderabad 500030, India; (S.K.M.); (M.S.); (R.M.S.); (N.N.C.); (A.S.S.)
- Correspondence: (S.K.); (R.K.V.); (G.M.); Tel.: +91-40-245-91268 (S.K.); +91-84-556-83305 (R.K.V.); +91-40-66303697 (G.M.)
| | - Rajeev K. Varshney
- Center of Excellence in Genomics & Systems Biology, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Hyderabad 502324, India;
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6009, Australia
- State Agricultural Biotechnology Centre, Centre for Crop and Food Innovation, Food Futures Institute, Murdoch University, Murdoch, WA 6150, Australia
- Correspondence: (S.K.); (R.K.V.); (G.M.); Tel.: +91-40-245-91268 (S.K.); +91-84-556-83305 (R.K.V.); +91-40-66303697 (G.M.)
| | - Gireesha Mohannath
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Hyderabad 500078, India; (G.P.S.); (S.M.)
- Correspondence: (S.K.); (R.K.V.); (G.M.); Tel.: +91-40-245-91268 (S.K.); +91-84-556-83305 (R.K.V.); +91-40-66303697 (G.M.)
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16
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Kelpšas V, von Wachenfeldt C. Enhancing protein perdeuteration by experimental evolution of Escherichia coli K-12 for rapid growth in deuterium-based media. Protein Sci 2021; 30:2457-2473. [PMID: 34655136 PMCID: PMC8605374 DOI: 10.1002/pro.4206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/07/2022]
Abstract
Deuterium is a natural low abundance stable hydrogen isotope that in high concentrations negatively affects growth of cells. Here, we have studied growth of Escherichia coli MG1655, a wild-type laboratory strain of E. coli K-12, in deuterated glycerol minimal medium. The growth rate and final biomass in deuterated medium is substantially reduced compared to cells grown in ordinary medium. By using a multi-generation adaptive laboratory evolution-based approach, we have isolated strains that show increased fitness in deuterium-based growth media. Whole-genome sequencing identified the genomic changes in the obtained strains and show that there are multiple routes to genetic adaptation to growth in deuterium-based media. By screening a collection of single-gene knockouts of nonessential genes, no specific gene was found to be essential for growth in deuterated minimal medium. Deuteration of proteins is of importance for NMR spectroscopy, neutron protein crystallography, neutron reflectometry, and small angle neutron scattering. The laboratory evolved strains, with substantially improved growth rate, were adapted for recombinant protein production by T7 RNA polymerase overexpression systems and shown to be suitable for efficient production of perdeuterated soluble and membrane proteins for structural biology applications.
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Affiliation(s)
- Vinardas Kelpšas
- The Microbiology Group, Department of Biology, Lund University, Lund, Sweden
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17
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Unappreciated Roles for K+ Channels in Bacterial Physiology. Trends Microbiol 2021; 29:942-950. [DOI: 10.1016/j.tim.2020.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/07/2020] [Accepted: 11/09/2020] [Indexed: 01/03/2023]
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18
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Deciphering ion transport and ATPase coupling in the intersubunit tunnel of KdpFABC. Nat Commun 2021; 12:5098. [PMID: 34429416 PMCID: PMC8385062 DOI: 10.1038/s41467-021-25242-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/29/2021] [Indexed: 02/07/2023] Open
Abstract
KdpFABC, a high-affinity K+ pump, combines the ion channel KdpA and the P-type ATPase KdpB to secure survival at K+ limitation. Here, we apply a combination of cryo-EM, biochemical assays, and MD simulations to illuminate the mechanisms underlying transport and the coupling to ATP hydrolysis. We show that ions are transported via an intersubunit tunnel through KdpA and KdpB. At the subunit interface, the tunnel is constricted by a phenylalanine, which, by polarized cation-π stacking, controls K+ entry into the canonical substrate binding site (CBS) of KdpB. Within the CBS, ATPase coupling is mediated by the charge distribution between an aspartate and a lysine. Interestingly, individual elements of the ion translocation mechanism of KdpFABC identified here are conserved among a wide variety of P-type ATPases from different families. This leads us to the hypothesis that KdpB might represent an early descendant of a common ancestor of cation pumps.
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19
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Abstract
Potassium is an essential mineral nutrient required by all living cells for normal physiological function. Therefore, maintaining intracellular potassium homeostasis during bacterial infection is a requirement for the survival of both host and pathogen. However, pathogenic bacteria require potassium transport to fulfill nutritional and chemiosmotic requirements, and potassium has been shown to directly modulate virulence gene expression, antimicrobial resistance, and biofilm formation. Host cells also require potassium to maintain fundamental biological processes, such as renal function, muscle contraction, and neuronal transmission; however, potassium flux also contributes to critical immunological and antimicrobial processes, such as cytokine production and inflammasome activation. Here, we review the role and regulation of potassium transport and signaling during infection in both mammalian and bacterial cells and highlight the importance of potassium to the success and survival of each organism.
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20
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A single residue deletion in the barley HKT1;5 P189 variant restores plasma membrane localisation but not Na + conductance. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183669. [PMID: 34139196 DOI: 10.1016/j.bbamem.2021.183669] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/12/2022]
Abstract
Leaf Na+ exclusion, mediated by plasma membrane-localised Class 1 High-affinity potassium (K+) Transporters (HKTs), is a key mechanism contributing to salinity tolerance of several major crop plants. We determined previously that the leucine to proline residue substitution at position 189 (L189P) in barley HvHKT1;5 disrupts its characteristic plasma membrane localisation and Na+ conductance. Here, we focus on a surprising observation that a single residue deletion of methionine at position 372 (M372del) within the conserved VMMYL motif in plant HKTs, restores plasma membrane localisation but not Na+ conductance in HvHKT1;5 P189. To clarify why the singular M372 deletion regains plasma membrane localisation, we built 3D models and defined α-helical assembly pathways of the P189 M372del mutant, and compared these findings to the wild-type protein, and the HvHKT1;5 L189 variant and its M372del mutant. We find that α-helical association and assembly pathways in HvHKT1;5 proteins fall in two contrasting categories. Inspections of structural flexibility through molecular dynamics simulations revealed that the conformational states of HvHKT1;5 P189 diverge from those of the L189 variant and M372del mutants. We propose that M372del in HvHKT1;5 P189 instigates structural rearrangements allowing routing to the plasma membrane, while the restoration of conductance would require further interventions. We integrate the microscopy, electrophysiology, and biocomputational data and discuss how a profound structural change in HvHKT1;5 P189 M372del impacts its α-helical protein association pathway and flexibility, and how these features underlie a delicate balance leading to restoring plasma membrane localisation but not Na+ conductance.
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21
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Ali A, Raddatz N, Pardo JM, Yun D. HKT sodium and potassium transporters in Arabidopsis thaliana and related halophyte species. PHYSIOLOGIA PLANTARUM 2021; 171:546-558. [PMID: 32652584 PMCID: PMC8048799 DOI: 10.1111/ppl.13166] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/30/2020] [Accepted: 07/06/2020] [Indexed: 05/10/2023]
Abstract
High salinity induces osmotic stress and often leads to sodium ion-specific toxicity, with inhibitory effects on physiological, biochemical and developmental pathways. To cope with increased Na+ in soil water, plants restrict influx, compartmentalize ions into vacuoles, export excess Na+ from the cell, and distribute ions between the aerial and root organs. In this review, we discuss our current understanding of how high-affinity K+ transporters (HKT) contribute to salinity tolerance, focusing on HKT1-like family members primarily involved in long-distance transport, and in the recent research in the model plant Arabidopsis and its halophytic counterparts of the Eutrema genus. Functional characterization of the salt overly sensitive (SOS) pathway and HKT1-type transporters in these species indicate that they utilize similar approaches to deal with salinity, regardless of their tolerance.
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Affiliation(s)
- Akhtar Ali
- Institute of Glocal Disease ControlKonkuk UniversitySeoul05029South Korea
- Department of Biomedical Science & EngineeringKonkuk UniversitySeoul05029South Korea
| | - Natalia Raddatz
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, CSIC‐Universidad de SevillaAmerico Vespucio 49, Sevilla41092Spain
| | - Jose M. Pardo
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, CSIC‐Universidad de SevillaAmerico Vespucio 49, Sevilla41092Spain
| | - Dae‐Jin Yun
- Department of Biomedical Science & EngineeringKonkuk UniversitySeoul05029South Korea
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22
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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: 55] [Impact Index Per Article: 18.3] [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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23
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Matamoros M, Nichols CG. Pore-forming transmembrane domains control ion selectivity and selectivity filter conformation in the KirBac1.1 potassium channel. J Gen Physiol 2021; 153:211923. [PMID: 33779689 PMCID: PMC8008366 DOI: 10.1085/jgp.202012683] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 11/23/2020] [Accepted: 03/09/2021] [Indexed: 01/10/2023] Open
Abstract
Potassium (K+) channels are membrane proteins with the remarkable ability to very selectively conduct K+ ions across the membrane. High-resolution structures have revealed that dehydrated K+ ions permeate through the narrowest region of the pore, formed by the backbone carbonyls of the signature selectivity filter (SF) sequence TxGYG. However, the existence of nonselective channels with similar SF sequences, as well as effects of mutations in other regions on selectivity, suggest that the SF is not the sole determinant of selectivity. We changed the selectivity of the KirBac1.1 channel by introducing mutations at residue I131 in transmembrane helix 2 (TM2). These mutations increase Na+ flux in the absence of K+ and introduce significant proton conductance. Consistent with K+ channel crystal structures, single-molecule FRET experiments show that the SF is conformationally constrained and stable in high-K+ conditions but undergoes transitions to dilated low-FRET states in high-Na+/low-K+ conditions. Relative to wild-type channels, I131M mutants exhibit marked shifts in the K+ and Na+ dependence of SF dynamics to higher K+ and lower Na+ concentrations. These results illuminate the role of I131, and potentially other structural elements outside the SF, in controlling ion selectivity, by suggesting that the physical interaction of these elements with the SF contributes to the relative stability of the constrained K+-induced SF configuration versus nonselective dilated conformations.
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Affiliation(s)
- Marcos Matamoros
- Center for Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
| | - Colin G Nichols
- Center for Investigation of Membrane Excitability Diseases, and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
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24
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Plant HKT Channels: An Updated View on Structure, Function and Gene Regulation. Int J Mol Sci 2021; 22:ijms22041892. [PMID: 33672907 PMCID: PMC7918770 DOI: 10.3390/ijms22041892] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/28/2022] Open
Abstract
HKT channels are a plant protein family involved in sodium (Na+) and potassium (K+) uptake and Na+-K+ homeostasis. Some HKTs underlie salt tolerance responses in plants, while others provide a mechanism to cope with short-term K+ shortage by allowing increased Na+ uptake under K+ starvation conditions. HKT channels present a functionally versatile family divided into two classes, mainly based on a sequence polymorphism found in the sequences underlying the selectivity filter of the first pore loop. Physiologically, most class I members function as sodium uniporters, and class II members as Na+/K+ symporters. Nevertheless, even within these two classes, there is a high functional diversity that, to date, cannot be explained at the molecular level. The high complexity is also reflected at the regulatory level. HKT expression is modulated at the level of transcription, translation, and functionality of the protein. Here, we summarize and discuss the structure and conservation of the HKT channel family from algae to angiosperms. We also outline the latest findings on gene expression and the regulation of HKT channels.
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25
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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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26
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Ding B, Zhang X, Xu Y, An L, Liu X, Su Q. The bacterial potassium transporter gene MbtrkH improves K+ uptake in yeast and tobacco. PLoS One 2020; 15:e0236246. [PMID: 32804956 PMCID: PMC7430745 DOI: 10.1371/journal.pone.0236246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 07/01/2020] [Indexed: 11/19/2022] Open
Abstract
K+ is an essential nutrient for plant growth and is responsible for many important physiological processes. K+ deficiency leads to crop yield losses, and overexpression of K+ transporter genes has been proven to be an effective way to resolve this problem. However, current research on the overexpression of K+ transporter genes is limited to plant sources. TrkH is a bacterial K+ transporter whose function generally depends on the regulation of TrkA. To date, whether TrkH can improve K+ uptake in eukaryotic organisms is still unknown. In this study, a novel MbtrkH gene was cloned from marine microbial metagenomic DNA. Functional complementation and K+-depletion analyses revealed that MbTrkH functions in K+ uptake in the K+-deficient yeast strain CY162. Moreover, K+-depletion assays revealed that MbtrkH overexpression improves plant K+ uptake. K+ hydroponic culture experiments showed that, compared with WT tobacco lines, MbtrkH transgenic tobacco lines had significantly greater fresh weights, dry weights and K+ contents. These results indicate that MbTrkH promotes K+ uptake independently of TrkA in eukaryotes and provide a new strategy for improving K+-use efficiency in plants.
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Affiliation(s)
- Baojuan Ding
- School of Bioengineering, Dalian University of Technology, Dalian, P. R. China
| | - Xiaoyan Zhang
- School of Bioengineering, Dalian University of Technology, Dalian, P. R. China
| | - Yongsheng Xu
- School of Bioengineering, Dalian University of Technology, Dalian, P. R. China
| | - Lijia An
- School of Bioengineering, Dalian University of Technology, Dalian, P. R. China
| | - Xiangguo Liu
- Institute of Agricultural Biotechnology, Jilin Academy of Agricultural Sciences, Changchun, P. R. China
| | - Qiao Su
- School of Bioengineering, Dalian University of Technology, Dalian, P. R. China
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27
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Somasundaram S, Véry AA, Vinekar RS, Ishikawa T, Kumari K, Pulipati S, Kumaresan K, Corratgé-Faillie C, Sowdhamini R, Parida A, Shabala L, Shabala S, Venkataraman G. Homology Modeling Identifies Crucial Amino-Acid Residues That Confer Higher Na+ Transport Capacity of OcHKT1;5 from Oryza coarctata Roxb. PLANT & CELL PHYSIOLOGY 2020; 61:1321-1334. [PMID: 32379873 DOI: 10.1093/pcp/pcaa061] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 04/28/2020] [Indexed: 05/20/2023]
Abstract
HKT1;5 loci/alleles are important determinants of crop salinity tolerance. HKT1;5s encode plasmalemma-localized Na+ transporters, which move xylem Na+ into xylem parenchyma cells, reducing shoot Na+ accumulation. Allelic variation in rice OsHKT1;5 sequence in specific landraces (Nona Bokra OsHKT1;5-NB/Nipponbare OsHKT1;5-Ni) correlates with variation in salt tolerance. Oryza coarctata, a halophytic wild rice, grows in fluctuating salinity at the seawater-estuarine interface in Indian and Bangladeshi coastal regions. The distinct transport characteristics of the shoots and roots expressing the O. coarctata OcHKT1;5 transporter are reported vis-à-vis OsHKT1;5-Ni. Yeast sodium extrusion-deficient cells expressing OcHKT1;5 are sensitive to increasing Na+ (10-100 mM). Electrophysiological measurements in Xenopus oocytes expressing O. coarctata or rice HKT1;5 transporters indicate that OcHKT1;5, like OsHKT1;5-Ni, is a Na+-selective transporter, but displays 16-fold lower affinity for Na+ and 3.5-fold higher maximal conductance than OsHKT1;5-Ni. For Na+ concentrations >10 mM, OcHKT1;5 conductance is higher than that of OsHKT1;5-Ni, indicating the potential of OcHKT1;5 for increasing domesticated rice salt tolerance. Homology modeling/simulation suggests that four key amino-acid changes in OcHKT1;5 (in loops on the extracellular side; E239K, G207R, G214R, L363V) account for its lower affinity and higher Na+ conductance vis-à-vis OsHKT1;5-Ni. Of these, E239K in OcHKT1;5 confers lower affinity for Na+ transport, as evidenced by Na+ transport assays of reciprocal site-directed mutants for both transporters (OcHKT1;5-K239E, OsHKT1;5-Ni-E270K) in Xenopus oocytes. Both transporters have likely analogous roles in xylem sap desalinization, and differences in xylem sap Na+ concentrations in both species are attributed to differences in Na+ transport affinity/conductance between the transporters.
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Affiliation(s)
- Suji Somasundaram
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600113, India
| | - Anne-Aliénor Véry
- Biochimie & Physiologie Moléculaire des Plantes, UMR Univ. Montpellier, CNRS, INRAE, SupAgro, 34060 Montpellier Cedex 2, France
| | - Rithvik S Vinekar
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 560 065, India
| | - Tetsuya Ishikawa
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, TAS 7001, Australia
| | - Kumkum Kumari
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600113, India
- Biochimie & Physiologie Moléculaire des Plantes, UMR Univ. Montpellier, CNRS, INRAE, SupAgro, 34060 Montpellier Cedex 2, France
| | - Shalini Pulipati
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600113, India
| | - Kavitha Kumaresan
- Krishi Vigyan Kendra, Thurupathisaram, Kanyakumari District, Tamil Nadu 629901, India
| | - Claire Corratgé-Faillie
- Biochimie & Physiologie Moléculaire des Plantes, UMR Univ. Montpellier, CNRS, INRAE, SupAgro, 34060 Montpellier Cedex 2, France
| | - R Sowdhamini
- National Centre for Biological Sciences, TIFR, GKVK Campus, Bellary Road, Bangalore 560 065, India
| | - Ajay Parida
- Institute of Life Sciences (ILS), NALCO Square, Bhubaneswar, Odisha 751023, India
| | - Lana Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, TAS 7001, Australia
| | - 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
| | - Gayatri Venkataraman
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600113, India
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28
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Ghebreamlak SM, Mansoorabadi SO. Divergent Members of the Nitrogenase Superfamily: Tetrapyrrole Biosynthesis and Beyond. Chembiochem 2020; 21:1723-1728. [PMID: 32180329 DOI: 10.1002/cbic.201900782] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 02/13/2020] [Indexed: 11/06/2022]
Abstract
The nitrogenase superfamily constitutes a large and diverse ensemble of two-component metalloenzymes. These systems couple the hydrolysis of ATP to the reduction of disparate substrates from diatomic gases (Mo and alternative nitrogenases) to photosynthetic pigments (protochlorophyllide and chlorophyllide oxidoreductases). Only very recently have the activities of the highly divergent and paraphyletic Group IV nitrogenases begun to be uncovered. This review highlights the first characterized member of this group, which was found to catalyze an unprecedented reaction in the coenzyme F430 biosynthetic pathway, and the catalytic potential of a superfamily that has yet to be fully explored.
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Affiliation(s)
- Selamawit M Ghebreamlak
- Department of Chemistry and Biochemistry, Auburn University 179 Chemistry Building, Auburn, AL, 36849, USA
| | - Steven O Mansoorabadi
- Department of Chemistry and Biochemistry, Auburn University 179 Chemistry Building, Auburn, AL, 36849, USA
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29
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Wani SH, Kumar V, Khare T, Guddimalli R, Parveda M, Solymosi K, Suprasanna P, Kavi Kishor PB. Engineering salinity tolerance in plants: progress and prospects. PLANTA 2020; 251:76. [PMID: 32152761 DOI: 10.1007/s00425-020-03366-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 02/24/2020] [Indexed: 05/20/2023]
Abstract
There is a need to integrate conceptual framework based on the current understanding of salt stress responses with different approaches for manipulating and improving salt tolerance in crop plants. Soil salinity exerts significant constraints on global crop production, posing a serious challenge for plant breeders and biotechnologists. The classical transgenic approach for enhancing salinity tolerance in plants revolves by boosting endogenous defence mechanisms, often via a single-gene approach, and usually involves the enhanced synthesis of compatible osmolytes, antioxidants, polyamines, maintenance of hormone homeostasis, modification of transporters and/or regulatory proteins, including transcription factors and alternative splicing events. Occasionally, genetic manipulation of regulatory proteins or phytohormone levels confers salinity tolerance, but all these may cause undesired reduction in plant growth and/or yields. In this review, we present and evaluate novel and cutting-edge approaches for engineering salt tolerance in crop plants. First, we cover recent findings regarding the importance of regulatory proteins and transporters, and how they can be used to enhance salt tolerance in crop plants. We also evaluate the importance of halobiomes as a reservoir of genes that can be used for engineering salt tolerance in glycophytic crops. Additionally, the role of microRNAs as critical post-transcriptional regulators in plant adaptive responses to salt stress is reviewed and their use for engineering salt-tolerant crop plants is critically assessed. The potentials of alternative splicing mechanisms and targeted gene-editing technologies in understanding plant salt stress responses and developing salt-tolerant crop plants are also discussed.
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Affiliation(s)
- Shabir Hussain Wani
- Mountain Research Centre for Field Crops, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Khudwani, Anantnag, Jammu and Kashmir, 192 101, India.
| | - Vinay Kumar
- Department of Biotechnology, Modern College, Savitribai Phule Pune University, Ganeshkhind, Pune, 411 016, India
- Department of Environmental Science, Savitribai Phule Pune University, Ganeshkhind, Pune, 411 016, India
| | - Tushar Khare
- Department of Biotechnology, Modern College, Savitribai Phule Pune University, Ganeshkhind, Pune, 411 016, India
| | | | | | - Katalin Solymosi
- Department of Plant Anatomy, Institute of Biology, ELTE-Eötvös Loránd University, Budapest, 1053, Hungary
| | - Penna Suprasanna
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400 085, India
| | - P B Kavi Kishor
- Department of Biotechnology, Vignan's Foundation for Science Technology and Research, Vadlamudi, Guntur, 522 213, India
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30
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Raddatz N, Morales de los Ríos L, Lindahl M, Quintero FJ, Pardo JM. Coordinated Transport of Nitrate, Potassium, and Sodium. FRONTIERS IN PLANT SCIENCE 2020; 11:247. [PMID: 32211003 PMCID: PMC7067972 DOI: 10.3389/fpls.2020.00247] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/18/2020] [Indexed: 05/19/2023]
Abstract
Potassium (K+) and nitrogen (N) are essential nutrients, and their absorption and distribution within the plant must be coordinated for optimal growth and development. Potassium is involved in charge balance of inorganic and organic anions and macromolecules, control of membrane electrical potential, pH homeostasis and the regulation of cell osmotic pressure, whereas nitrogen is an essential component of amino acids, proteins, and nucleic acids. Nitrate (NO3 -) is often the primary nitrogen source, but it also serves as a signaling molecule to the plant. Nitrate regulates root architecture, stimulates shoot growth, delays flowering, regulates abscisic acid-independent stomata opening, and relieves seed dormancy. Plants can sense K+/NO3 - levels in soils and adjust accordingly the uptake and root-to-shoot transport to balance the distribution of these ions between organs. On the other hand, in small amounts sodium (Na+) is categorized as a "beneficial element" for plants, mainly as a "cheap" osmolyte. However, at high concentrations in the soil, Na+ can inhibit various physiological processes impairing plant growth. Hence, plants have developed specific mechanisms to transport, sense, and respond to a variety of Na+ conditions. Sodium is taken up by many K+ transporters, and a large proportion of Na+ ions accumulated in shoots appear to be loaded into the xylem by systems that show nitrate dependence. Thus, an adequate supply of mineral nutrients is paramount to reduce the noxious effects of salts and to sustain crop productivity under salt stress. In this review, we will focus on recent research unraveling the mechanisms that coordinate the K+-NO3 -; Na+-NO3 -, and K+-Na+ transports, and the regulators controlling their uptake and allocation.
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Affiliation(s)
| | | | | | | | - José M. Pardo
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Científicas and Universidad de Sevilla, Seville, Spain
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31
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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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32
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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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Mikušević V, Schrecker M, Kolesova N, Patiño-Ruiz M, Fendler K, Hänelt I. A channel profile report of the unusual K + channel KtrB. J Gen Physiol 2019; 151:1357-1368. [PMID: 31624134 PMCID: PMC6888753 DOI: 10.1085/jgp.201912384] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 09/03/2019] [Accepted: 09/27/2019] [Indexed: 11/20/2022] Open
Abstract
KtrAB is a key player in bacterial K+ uptake required for K+ homeostasis and osmoadaptation. The system is unique in structure and function. It consists of the K+-translocating channel subunit KtrB, which forms a dimer in the membrane, and the soluble regulatory subunit KtrA, which attaches to the cytoplasmic side of the dimer as an octameric ring conferring Na+ and ATP dependency to the system. Unlike most K+ channels, KtrB lacks the highly conserved T(X)GYG selectivity filter sequence. Instead, only a single glycine residue is found in each pore loop, which raises the question of how selective the ion channel is. Here, we characterized the KtrB subunit from the Gram-negative pathogen Vibrio alginolyticus by isothermal titration calorimetry, solid-supported membrane-based electrophysiology, whole-cell K+ uptake, and ACMA-based transport assays. We found that, despite its simple selectivity filter, KtrB selectively binds K+ with micromolar affinity. Rb+ and Cs+ bind with millimolar affinities. However, only K+ and the poorly binding Na+ are efficiently translocated, based on size exclusion by the gating loop. Importantly, the physiologically required K+ over Na+ selectivity is provided by the channel's high affinity for potassium, which interestingly results from the presence of the sodium ions themselves. In the presence of the KtrA subunit, sodium ions further decrease the Michaelis-Menten constant for K+ uptake from milli- to micromolar concentrations and increase the Vmax, suggesting that Na+ also facilitates channel gating. In conclusion, high binding affinity and facilitated K+ gating allow KtrAB to function as a selective K+ channel.
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Affiliation(s)
- Vedrana Mikušević
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Marina Schrecker
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Natalie Kolesova
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Miyer Patiño-Ruiz
- Department of Biophysical Chemistry, Max Planck Institute for Biophysics, Frankfurt, Germany
| | - Klaus Fendler
- Department of Biophysical Chemistry, Max Planck Institute for Biophysics, Frankfurt, Germany
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany
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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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Wang JW, Gao J, Wang HF, Jin QH, Rao B, Deng W, Cao Y, Lei M, Ye S, Fang Q. Miniaturization of the Whole Process of Protein Crystallographic Analysis by a Microfluidic Droplet Robot: From Nanoliter-Scale Purified Proteins to Diffraction-Quality Crystals. Anal Chem 2019; 91:10132-10140. [PMID: 31276402 DOI: 10.1021/acs.analchem.9b02138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To obtain diffraction-quality crystals is one of the largest barriers to analyze the protein structure using X-ray crystallography. Here we describe a microfluidic droplet robot that enables successful miniaturization of the whole process of crystallization experiments including large-scale initial crystallization screening, crystallization optimization, and crystal harvesting. The combination of the state-of-the-art droplet-based microfluidic technique with the microbatch crystallization mode dramatically reduces the volumes of droplet crystallization reactors to tens nanoliter range, allowing large-scale initial screening of 1536 crystallization conditions and multifactor crystallization condition optimization with extremely low protein consumption, and on-chip harvesting of diffraction-quality crystals directly from the droplet reactors. We applied the droplet robot in miniaturized crystallization experiments of seven soluble proteins and two membrane proteins, and on-chip crystal harvesting of six proteins. The X-ray diffraction data sets of these crystals were collected using synchrotron radiation for analyzing the structures with similar diffraction qualities as conventional crystallization methods.
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Affiliation(s)
- Jian-Wei Wang
- Institute of Microanalytical Systems, Department of Chemistry , Zhejiang University , Hangzhou , 310058 , China
| | - Jie Gao
- Institute of Microanalytical Systems, Department of Chemistry , Zhejiang University , Hangzhou , 310058 , China
| | - Hui-Feng Wang
- Institute of Microanalytical Systems, Department of Chemistry , Zhejiang University , Hangzhou , 310058 , China
| | - Qiu-Heng Jin
- Life Sciences Institute , Zhejiang University , Hangzhou , 310058 , China
| | - Bing Rao
- State Key Laboratory of Molecular Biology , National Center for Protein Science · Shanghai , Shanghai , 201210 , China
| | - Wei Deng
- State Key Laboratory of Molecular Biology , National Center for Protein Science · Shanghai , Shanghai , 201210 , China
| | - Yu Cao
- State Key Laboratory of Molecular Biology , National Center for Protein Science · Shanghai , Shanghai , 201210 , China
| | - Ming Lei
- State Key Laboratory of Molecular Biology , National Center for Protein Science · Shanghai , Shanghai , 201210 , China
| | - Sheng Ye
- Life Sciences Institute , Zhejiang University , Hangzhou , 310058 , China.,School of Life Sciences , Tianjin University , Tianjin , 300072 , China
| | - Qun Fang
- Institute of Microanalytical Systems, Department of Chemistry , Zhejiang University , Hangzhou , 310058 , China
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Selvam B, Yu YC, Chen LQ, Shukla D. Molecular Basis of the Glucose Transport Mechanism in Plants. ACS CENTRAL SCIENCE 2019; 5:1085-1096. [PMID: 31263768 PMCID: PMC6598156 DOI: 10.1021/acscentsci.9b00252] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Indexed: 05/04/2023]
Abstract
The SWEET family belongs to a class of transporters in plants that undergoes large conformational changes to facilitate transport of sugar molecules across the cell membrane (SWEET, Sugars Will Eventually Be Exported Transporter). However, the structures of their functionally relevant conformational states in the transport cycle have not been reported. In this study, we have characterized the conformational dynamics and complete transport cycle of glucose in the OsSWEET2b transporter using extensive molecular dynamics simulations. Using Markov state models, we estimated the free energy barrier associated with different states as well as for the glucose transport mechanism. SWEETs undergo a structural transition to outward-facing (OF), occluded (OC), and inward-facing (IF) and strongly support an alternate access transport mechanism. The glucose diffuses freely from outside to inside the cell without causing major conformational changes which means that the conformations of glucose unbound and bound snapshots are exactly the same for OF, OC, and IF states. We identified a network of hydrophobic core residues at the center of the transporter that restricts the glucose entry to the cytoplasmic side and acts as an intracellular hydrophobic gate. The mechanistic predictions from molecular dynamics simulations are validated using site-directed mutagenesis experiments. Our simulation also revealed hourglass-like intermediate states making the pore radius narrower at the center. This work provides new fundamental insights into how substrate-transporter interactions actively change the free energy landscape of the transport cycle to facilitate enhanced transport activity.
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Affiliation(s)
- Balaji Selvam
- Department
of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ya-Chi Yu
- Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Li-Qing Chen
- Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Diwakar Shukla
- Department
of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois 61801, United States
- Center
for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- NIH
Center for Macromolecular Modeling and Bioinformatics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman
Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- E-mail:
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Li X, Gu AZ, Zhang Y, Xie B, Li D, Chen J. Sub-lethal concentrations of heavy metals induce antibiotic resistance via mutagenesis. JOURNAL OF HAZARDOUS MATERIALS 2019; 369:9-16. [PMID: 30753956 DOI: 10.1016/j.jhazmat.2019.02.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 01/31/2019] [Accepted: 02/03/2019] [Indexed: 05/20/2023]
Abstract
The emergence of antibiotic resistance is a growing problem worldwide. Numerous studies have demonstrated that heavy metals facilitate the spread of bacterial drug-resistance in the environment. However, the actions and mechanisms of metals at relatively low sub-lethal levels (far below the minimal inhibitory concentration [MIC]) on antibiotic resistance remain unclear. In this study, we investigated the effect of sub-lethal levels of heavy metals [Ag(I), Zn(II), and Cu(II)] on antibiotic resistance and explored the underlying mechanisms. The results demonstrated that sub-lethal levels of metal ions increased the mutation rates and enriched de novo mutants that exhibited significant resistance to multiple antibiotics. The resistant mutants exhibited hereditary resistance after 5-day of sub-culture. Whole-genome analysis revealed distinct mutations in genes involved in multiple drug and drug-specific resistance, as well as genes that are not associated with antibiotic resistance to data. The number and identities of genetic changes were distinct for mutants induced by different metals. This study provides evidence and mechanistic insights into the induction of antibiotic resistance by sub-lethal concentrations of heavy metals, which may enhance the emergence of antibiotic resistance in various environments. More consideration and regulations should be given to this potential health risk for long-standing and harmful heavy metals.
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Affiliation(s)
- Xiangyang Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China; College of Environment and Life Sciences, Kaili University, Kaiyuan Road, 556011, Kaili, China
| | - April Z Gu
- School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, 14853, United States
| | - Ye Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Bin Xie
- Pure and Applied Biochemistry, Department of Chemistry, Lund University, Box 124, SE, 22100, Lund, Sweden
| | - Dan Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China.
| | - Jianmin Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
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Xu X, Williams TC, Divne C, Pretorius IS, Paulsen IT. Evolutionary engineering in Saccharomyces cerevisiae reveals a TRK1-dependent potassium influx mechanism for propionic acid tolerance. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:97. [PMID: 31044010 PMCID: PMC6477708 DOI: 10.1186/s13068-019-1427-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Propionic acid (PA), a key platform chemical produced as a by-product during petroleum refining, has been widely used as a food preservative and an important chemical intermediate in many industries. Microbial PA production through engineering yeast as a cell factory is a potentially sustainable alternative to replace petroleum refining. However, PA inhibits yeast growth at concentrations well below the titers typically required for a commercial bioprocess. RESULTS Adaptive laboratory evolution (ALE) with PA concentrations ranging from 15 to 45 mM enabled the isolation of yeast strains with more than threefold improved tolerance to PA. Through whole genome sequencing and CRISPR-Cas9-mediated reverse engineering, unique mutations in TRK1, which encodes a high-affinity potassium transporter, were revealed as the cause of increased propionic acid tolerance. Potassium supplementation growth assays showed that mutated TRK1 alleles and extracellular potassium supplementation not only conferred tolerance to PA stress but also to multiple organic acids. CONCLUSION Our study has demonstrated the use of ALE as a powerful tool to improve yeast tolerance to PA. Potassium transport and maintenance is not only critical in yeast tolerance to PA but also boosts tolerance to multiple organic acids. These results demonstrate high-affinity potassium transport as a new principle for improving organic acid tolerance in strain engineering.
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Affiliation(s)
- Xin Xu
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109 Australia
| | - Thomas C. Williams
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109 Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, ACT 2601 Australia
| | - Christina Divne
- KTH School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
| | - Isak S. Pretorius
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109 Australia
| | - Ian T. Paulsen
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109 Australia
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40
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Fluctuating selection on migrant adaptive sodium transporter alleles in coastal Arabidopsis thaliana. Proc Natl Acad Sci U S A 2018; 115:E12443-E12452. [PMID: 30530653 PMCID: PMC6310793 DOI: 10.1073/pnas.1816964115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Stressors such as soil salinity and dehydration are major constraints on plant growth, causing worldwide crop losses. Compounding these insults, increasing climate volatility requires adaptation to fluctuating conditions. Salinity stress responses are relatively well understood in Arabidopsis thaliana, making this system suited for the rapid molecular dissection of evolutionary mechanisms. In a large-scale genomic analysis of Catalonian A. thaliana, we resequenced 77 individuals from multiple salinity gradients along the coast and integrated these data with 1,135 worldwide A. thaliana genomes for a detailed understanding of the demographic and evolutionary dynamics of naturally evolved salinity tolerance. This revealed that Catalonian varieties adapted to highly fluctuating soil salinity are not Iberian relicts but instead have immigrated to this region more recently. De novo genome assembly of three allelic variants of the high-affinity K+ transporter (HKT1;1) locus resolved structural variation between functionally distinct alleles undergoing fluctuating selection in response to seasonal changes in soil salinity. Plants harboring alleles responsible for low root expression of HKT1;1 and consequently high leaf sodium (HKT1;1 HLS ) were migrants that have moved specifically into areas where soil sodium levels fluctuate widely due to geography and rainfall variation. We demonstrate that the proportion of plants harboring HKT1;1 HLS alleles correlates with soil sodium level over time, HKT1;1 HLS -harboring plants are better adapted to intermediate levels of salinity, and the HKT1;1 HLS allele clusters with high-sodium accumulator accessions worldwide. Together, our evidence suggests that HKT1;1 is under fluctuating selection in response to climate volatility and is a worldwide determinant in adaptation to saline conditions.
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41
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Hrmova M, Gilliham M. Plants fighting back: to transport or not to transport, this is a structural question. CURRENT OPINION IN PLANT BIOLOGY 2018; 46:68-76. [PMID: 30138844 DOI: 10.1016/j.pbi.2018.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/06/2018] [Accepted: 07/12/2018] [Indexed: 06/08/2023]
Abstract
Membrane-embedded transport proteins are fundamental to life; their co-ordinated action controls the movement and distribution of solutes into, around and out of cells for signalling, metabolism, nutrition, stress tolerance and development. Here we outline two case studies of transport systems that plants use to tolerate soil elemental toxicity, demonstrating how iterative studies of protein structure and function result in unparalleled insights into transport mechanics. Further, we propose that integrative platforms of biological, biochemical and biophysical tools can provide quantitative data on substrate specificity and transport rates, which are important in understanding transporter evolution and their roles in cell biology and whole plant physiology. Such knowledge equips biotechnologists and breeders with the power to deliver improvements in crop yields in sub-optimal soils.
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Affiliation(s)
- Maria Hrmova
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia; School of Life Sciences, Huaiyin Normal University, Huai'an 223300, China.
| | - Matthew Gilliham
- School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, South Australia 5064, Australia; Australian Research Council Centre of Excellence in Plant Energy Biology, University of Adelaide, Waite Research Institute, Glen Osmond, South Australia 5064, Australia
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Hedrich R, Shabala S. Stomata in a saline world. CURRENT OPINION IN PLANT BIOLOGY 2018; 46:87-95. [PMID: 30138845 DOI: 10.1016/j.pbi.2018.07.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/18/2018] [Accepted: 07/25/2018] [Indexed: 05/20/2023]
Abstract
Salt stress results in a dramatic increase in ABA biosynthesis, H2O2 accumulation, and reduced K+ availability in the shoot. Each of these factors leads to stomata closure, so reducing CO2 assimilation and imposing yield penalties. However, halophytes, naturally salt tolerant plant species, flourish under saline conditions that would cause massive yield penalties in glycophytic crops. Is there anything special about the stomata of halophytes, why is guard cell function in these salt tolerant species not affected by the above factors? This opinion paper addresses these questions by providing a comprehensive assessment of the molecular identity and operational modes of major plasma membrane transporters that mediate stomata movements.
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Affiliation(s)
- Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University Wuerzburg, D-97070 Wuerzburg, Germany; Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tas 7001, Australia.
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tas 7001, Australia; Department of Horticulture, Foshan University, Foshan 528000, China.
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Cryo-EM structures of KdpFABC suggest a K + transport mechanism via two inter-subunit half-channels. Nat Commun 2018; 9:4971. [PMID: 30478378 PMCID: PMC6255902 DOI: 10.1038/s41467-018-07319-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Abstract
P-type ATPases ubiquitously pump cations across biological membranes to maintain vital ion gradients. Among those, the chimeric K+ uptake system KdpFABC is unique. While ATP hydrolysis is accomplished by the P-type ATPase subunit KdpB, K+ has been assumed to be transported by the channel-like subunit KdpA. A first crystal structure uncovered its overall topology, suggesting such a spatial separation of energizing and transporting units. Here, we report two cryo-EM structures of the 157 kDa, asymmetric KdpFABC complex at 3.7 Å and 4.0 Å resolution in an E1 and an E2 state, respectively. Unexpectedly, the structures suggest a translocation pathway through two half-channels along KdpA and KdpB, uniting the alternating-access mechanism of actively pumping P-type ATPases with the high affinity and selectivity of K+ channels. This way, KdpFABC would function as a true chimeric complex, synergizing the best features of otherwise separately evolved transport mechanisms.
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44
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Pan Y, Zhang Y, Gongpan P, Zhang Q, Huang S, Wang B, Xu B, Shan Y, Xiong W, Li G, Wang H. Single glucose molecule transport process revealed by force tracing and molecular dynamics simulations. NANOSCALE HORIZONS 2018; 3:517-524. [PMID: 32254137 DOI: 10.1039/c8nh00056e] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transporting individual molecules across cell membranes is a fundamental process in cellular metabolism. Although the crystal diffraction technique has greatly contributed to our understanding of the structures of the involved transporters, a description of the dynamic transport mechanism at the single-molecule level has been extremely elusive. In this study, we applied atomic force microscopy (AFM)-based force tracing to directly monitor the transport of a single molecule, d-glucose, across living cell membranes. Our results show that the force to transport a single molecule of d-glucose across cell membranes is 37 ± 9 pN, and the corresponding transport interval is approximately 20 ms, while the average speed is approximately 0.3 μm s-1. Furthermore, our calculated force profile from molecular dynamics simulations showed quantitatively good agreement with the force tracing observation and revealed detailed information regarding the glucose transport path, indicating that two salt bridges, K38/E299 and K300/E426, play critical roles during glucose transport across glucose transporter 1 (GLUT1). This role was further verified using biological experiments that disrupted these two bridges and measured the uptake of glucose into the cells. Our approaches led to the first unambiguous description of the glucose transport process across cell membranes at the single-molecule level and demonstrated the biological importance of the two salt bridges for transporting glucose across GLUT1.
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Affiliation(s)
- Yangang Pan
- State Key Laboratory of Electroanalytical Chemistry, Research Center of Biomembranomics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P. R. China.
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45
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46
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Xu B, Waters S, Byrt CS, Plett D, Tyerman SD, Tester M, Munns R, Hrmova M, Gilliham M. Structural variations in wheat HKT1;5 underpin differences in Na + transport capacity. Cell Mol Life Sci 2018; 75:1133-1144. [PMID: 29177534 PMCID: PMC11105589 DOI: 10.1007/s00018-017-2716-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/31/2017] [Accepted: 11/16/2017] [Indexed: 12/01/2022]
Abstract
An important trait associated with the salt tolerance of wheat is the exclusion of sodium ions (Na+) from the shoot. We have previously shown that the sodium transporters TmHKT1;5-A and TaHKT1;5-D, from Triticum monoccocum (Tm) and Triticum aestivum (Ta), are encoded by genes underlying the major shoot Na+-exclusion loci Nax1 and Kna1, respectively. Here, using heterologous expression, we show that the affinity (K m) for the Na+ transport of TmHKT1;5-A, at 2.66 mM, is higher than that of TaHKT1;5-D at 7.50 mM. Through 3D structural modelling, we identify residues D471/a gap and D474/G473 that contribute to this property. We identify four additional mutations in amino acid residues that inhibit the transport activity of TmHKT1;5-A, which are predicted to be the result of an occlusion of the pore. We propose that the underlying transport properties of TmHKT1;5-A and TaHKT1;5-D contribute to their unique ability to improve Na+ exclusion in wheat that leads to an improved salinity tolerance in the field.
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Affiliation(s)
- Bo Xu
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Shane Waters
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Caitlin S Byrt
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Darren Plett
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Stephen D Tyerman
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Mark Tester
- Division of Biological and Environmental Sciences and Engineering, Center for Desert Agriculture, King Abdullah University of Science and Technology, 4700, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Rana Munns
- School of Agriculture and Environment, and ARC Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, 6009, Australia
| | - Maria Hrmova
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia.
| | - Matthew Gilliham
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia.
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia.
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He B, Li H, Zeng B. Genome-wide Identification and Expression Analysis of the TRK Gene Family in Aspergillus oryzae. PROCEEDINGS OF THE 2018 8TH INTERNATIONAL CONFERENCE ON BIOSCIENCE, BIOCHEMISTRY AND BIOINFORMATICS 2018. [DOI: 10.1145/3180382.3180408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Affiliation(s)
- Bin He
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
| | - Haoran Li
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
| | - Bin Zeng
- Jiangxi Science & Technology, Normal University, Nanchang, Jiangxi, China
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Kumar S, Beena AS, Awana M, Singh A. Physiological, Biochemical, Epigenetic and Molecular Analyses of Wheat ( Triticum aestivum) Genotypes with Contrasting Salt Tolerance. FRONTIERS IN PLANT SCIENCE 2017; 8:1151. [PMID: 28713411 PMCID: PMC5491648 DOI: 10.3389/fpls.2017.01151] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/15/2017] [Indexed: 05/03/2023]
Abstract
Abiotic stress exerts significant impact on plant's growth, development, and productivity. Productivity of crop plants under salt stress is lagging behind because of our limited knowledge about physiological, biochemical, epigenetic, and molecular mechanisms of salt tolerance in plants. This study aimed to investigate physio-biochemical, molecular indices and defense responses of selected wheat cultivars to identify the most contrasting salt-responsive genotypes and the mechanisms associated with their differential responses. Physio-biochemical traits specifically membrane stability index, antioxidant potential, osmoprotectants and chlorophyll contents, measured at vegetative stage, were used for multivariate analysis to identify the most contrasting genotypes. Genetic and epigenetic analyses indicated the possible mechanisms associated with differential response of the wheat genotypes under salt stress. Better antioxidant potential, membrane stability, increased accumulation of osmolytes/phytophenolics, and higher K+/Na+ ratio under 200 mM NaCl stress identified Kharchia-65 to be the most salt-tolerant cultivar. By contrast, increased MDA level, reduced soluble sugar, proline, total chlorophyll, total phenolics contents, and lower antioxidant potential in HD-2329 marked it to be sensitive to the stress. Genetic and bioinformatics analyses of HKT1;4 of contrasting genotypes (Kharchia-65 and HD-2329) revealed deletions, transitions, and transversions resulting into altered structure, loss of conserved motifs (Ser-Gly-Gly-Gly and Gly-Arg) and function in salt-sensitive (HD-2329) genotype. Expression analysis of HKTs rationalized the observed responses. Epigenetic variations in cytosine methylation explained tissue- and genotype-specific differential expression of HKT2;1 and HKT2;3.
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Affiliation(s)
- Suresh Kumar
- Division of Biochemistry, ICAR – Indian Agricultural Research InstituteNew Delhi, India
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49
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Abstract
Cellular potassium import systems play a fundamental role in osmoregulation, pH homeostasis and membrane potential in all domains of life. In bacteria, the kdp operon encodes a four subunit potassium pump that maintains intracellular homeostasis as well as cell shape and turgor under conditions where potassium is limiting1. This membrane complex, called KdpFABC, has one channel-like subunit (KdpA) belonging to the Superfamily of Potassium Transporters and another pump-like subunit (KdpB) belonging to the Superfamily of P-type ATPases. Although there is considerable structural and functional information about members from both superfamilies, the mechanism by which uphill potassium transport through KdpA is coupled with ATP hydrolysis by KdpB remains poorly understood. Here we report the 2.9 Å X-ray structure of the complete Escherichia coli KdpFABC complex with a potassium ion within the selectivity filter of KdpA as well as a water molecule at a canonical cation site in the transmembrane domain of KdpB. The structure also reveals two structural elements that appear to mediate the coupling between these two subunits. Specifically, a protein-embedded tunnel runs between these potassium and water sites and a helix controlling the cytoplasmic gate of KdpA is linked to the phosphorylation domain of KdpB. Based on these observations, we propose an unprecedented mechanism that repurposes protein channel architecture for active transport across biomembranes.
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Affiliation(s)
- Ching-Shin Huang
- Molecular Biophysics Graduate Program, New York University School of Medicine, Skirball Institute, 540 First Avenue, New York, New York 10016, USA
| | - Bjørn Panyella Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, DK-8000 Aarhus C, Denmark
| | - David L Stokes
- Department of Cell Biology, New York University School of Medicine, Skirball Institute, 540 First Avenue, New York, New York 10016, USA
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50
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Diskowski M, Mehdipour AR, Wunnicke D, Mills DJ, Mikusevic V, Bärland N, Hoffmann J, Morgner N, Steinhoff HJ, Hummer G, Vonck J, Hänelt I. Helical jackknives control the gates of the double-pore K + uptake system KtrAB. eLife 2017; 6. [PMID: 28504641 PMCID: PMC5449183 DOI: 10.7554/elife.24303] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 05/14/2017] [Indexed: 12/27/2022] Open
Abstract
Ion channel gating is essential for cellular homeostasis and is tightly controlled. In some eukaryotic and most bacterial ligand-gated K+ channels, RCK domains regulate ion fluxes. Until now, a single regulatory mechanism has been proposed for all RCK-regulated channels, involving signal transduction from the RCK domain to the gating area. Here, we present an inactive ADP-bound structure of KtrAB from Vibrio alginolyticus, determined by cryo-electron microscopy, which, combined with EPR spectroscopy and molecular dynamics simulations, uncovers a novel regulatory mechanism for ligand-induced action at a distance. Exchange of activating ATP to inactivating ADP triggers short helical segments in the K+-translocating KtrB dimer to organize into two long helices that penetrate deeply into the regulatory RCK domains, thus connecting nucleotide-binding sites and ion gates. As KtrAB and its homolog TrkAH have been implicated as bacterial pathogenicity factors, the discovery of this functionally relevant inactive conformation may advance structure-guided drug development. DOI:http://dx.doi.org/10.7554/eLife.24303.001
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Affiliation(s)
- Marina Diskowski
- Institute of Biochemistry, Goethe-University, Frankfurt, Germany
| | - Ahmad Reza Mehdipour
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Dorith Wunnicke
- Institute of Biochemistry, Goethe-University, Frankfurt, Germany
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | | | - Natalie Bärland
- Institute of Biochemistry, Goethe-University, Frankfurt, Germany.,Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Jan Hoffmann
- Institute for Physical and Theoretical Chemistry, Goethe-University, Frankfurt, Germany
| | - Nina Morgner
- Institute for Physical and Theoretical Chemistry, Goethe-University, Frankfurt, Germany
| | | | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany.,Institute of Biophysics, Goethe-University, Frankfurt, Germany
| | - Janet Vonck
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Inga Hänelt
- Institute of Biochemistry, Goethe-University, Frankfurt, Germany
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