1
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Sun J, Ding Y, Zhou Q, Kalds P, Han J, Zhang K, Wei Y, Wu W, Wang X, Zheng W. KCNE4 is a crucial host factor for Orf virus infection by mediating viral entry. Virol J 2024; 21:181. [PMID: 39118175 PMCID: PMC11308312 DOI: 10.1186/s12985-024-02454-3] [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: 04/28/2024] [Accepted: 07/31/2024] [Indexed: 08/10/2024] Open
Abstract
The orf virus (ORFV) poses a serious threat to the health of domestic small ruminants (i.e., sheep and goats) and humans on a global scale, causing around $150 million in annual losses to livestock industry. However, the host factors involved in ORFV infection and replication are still elusive. In this study, we compared the RNA-seq profiles of ORFV-infected or non-infected sheep testicular interstitial cells (STICs) and identified a novel host gene, potassium voltage-gated channel subfamily E member 4 (KCNE4), as a key host factor involved in the ORFV infection. Both RNA-seq data and RT-qPCR assay revealed a significant increase in the expression of KCNE4 in the infected STICs from 9 to 48 h post infection (hpi). On the other hand, the RT-qPCR assay detected a decrease in ORFV copy number in both the STICs transfected by KCNE4 siRNA and the KCNE4 knockout (KO) HeLa cells after the ORFV infection, together with a reduced fluorescence ratio of ORFV-GFP in the KO HeLa cells at 24 hpi, indicating KCNE4 to be critical for the ORFV infection. Furthermore, the attachment and internalization assays showed decreased ORFV attachment, internalization, replication, and release by the KO HeLa cells, demonstrating a potential inhibition of ORFV entry into the cells by KCNE4. Pretreatment with the KCNE4 inhibitors such as quinidine and fluoxetine significantly repressed the ORFV infection. All our findings reveal KCNE4 as a novel host regulator of the ORFV entry and replication, shedding new insight into the interactive mechanism of ORFV infection. The study also highlights the K+ channels as possible druggable targets to impede viral infection and disease.
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Affiliation(s)
- Jiayuan Sun
- International Joint Agriculture Research Center for Animal Bio-breeding, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Yige Ding
- International Joint Agriculture Research Center for Animal Bio-breeding, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Qian Zhou
- International Joint Agriculture Research Center for Animal Bio-breeding, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
| | - Peter Kalds
- Yazhouwan National Laboratory, Sanya, 572024, China
| | - Jianlin Han
- Yazhouwan National Laboratory, Sanya, 572024, China
| | - Keshan Zhang
- Guangdong Provincial Key Laboratory of Animal Molecular Design and Precise Breeding, School of Life Science and Engineering, Foshan University, Foshan, 528225, China
| | - Yinghui Wei
- International Joint Agriculture Research Center for Animal Bio-breeding, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
- Key Laboratory of Livestock Biology, Northwest A&F University, Yangling, 712100, China
- School of Future Technology on Bio-breeding, Northwest A&F University, Yangling, 712100, China
| | - Weiwei Wu
- Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, 830011, China
| | - Xiaolong Wang
- International Joint Agriculture Research Center for Animal Bio-breeding, Ministry of Agriculture and Rural Affairs, College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China.
- Key Laboratory of Livestock Biology, Northwest A&F University, Yangling, 712100, China.
- School of Future Technology on Bio-breeding, Northwest A&F University, Yangling, 712100, China.
| | - Wenxin Zheng
- Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, 830011, China.
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2
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Gibby WAT, Barabash ML, Khovanov IA, Luchinsky DG, McClintock PVE. Ionic Coulomb blockade controls the current in a short narrow carbon nanotube. J Chem Phys 2024; 161:054710. [PMID: 39092950 DOI: 10.1063/5.0210853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 07/11/2024] [Indexed: 08/04/2024] Open
Abstract
We use all-atom molecular dynamics simulations to investigate ionic conduction in a short, charged, single-wall carbon nanotube. They reveal ionic Coulomb blockade (ICB) oscillations in the current as a function of the fixed charge on the wall, and an associated occupancy staircase. Current peaks related to fluctuations around the 2 → 1 and 1 → 0 steps in occupancy are clearly resolved, in agreement with ICB theory. Current peaks were also observed at constant occupancy. These unpredicted secondary peaks are attributed to edge effects involving a remote knock-on mechanism; they are attenuated, or absent, for certain choices of model parameters. The key parameters of the system that underlie the current oscillations are estimated using ICB theory and the potential of the mean force. Future perspectives opened up by these observations are discussed.
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Affiliation(s)
- William A T Gibby
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Miraslau L Barabash
- Department of Chemical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Igor A Khovanov
- School of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Dmitry G Luchinsky
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
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3
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Brahma R, Raghuraman H. Characterization of a novel MgtE homolog and its structural dynamics in membrane mimetics. Biophys J 2024; 123:1968-1983. [PMID: 38042987 PMCID: PMC11309985 DOI: 10.1016/j.bpj.2023.11.3402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/03/2023] [Accepted: 11/30/2023] [Indexed: 12/04/2023] Open
Abstract
Magnesium (Mg2+) is the most abundant divalent cation in the cell and is critical for numerous cellular processes. Despite its importance, the mechanisms of intracellular Mg2+ transport and its regulation are poorly understood. MgtE is the main Mg2+ transport system in almost half of bacterial species and is an ortholog of mammalian SLC41A1 transporters, which are implicated in neurodegenerative diseases and cancer. To date, only MgtE from Thermus thermophilus (MgtETT) has been extensively characterized, mostly in detergent micelles, and gating-related structural dynamics in biologically relevant membranes are scarce. The MgtE homolog from Bacillus firmus (MgtEBF) is unique since it lacks the entire Mg2+-sensing N-domain but has conserved structural motifs in the TM-domain for Mg2+ transport. In this work, we have successfully purified this novel homolog in a stable and functional form, and ColabFold structure prediction analysis suggests a homodimer. Further, microscale thermophoresis experiments show that MgtEBF binds Mg2+ and ATP, similar to MgtETT. Importantly, we show that, despite lacking the N-domain, MgtEBF mediates Mg2+ transport function in the presence of an inwardly directed Mg2+ gradient in reconstituted proteoliposomes. Furthermore, comparison of the organization and dynamics of Trp residues in the TM-domain of MgtEBF in membrane mimetics, in apo- and Mg2+-bound forms, suggests that the cytoplasmic binding of Mg2+ might involve modest gating-related conformational changes at the TM-domain. Overall, our results show that the gating-related structural dynamics (hydration dynamics, conformational heterogeneity) of the full-length MgtEBF is significantly changed in functionally pertinent membrane environment, emphasizing the importance of lipid-protein interactions in MgtE gating mechanisms.
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Affiliation(s)
- Rupasree Brahma
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India; Homi Bhabha National Institute, Training School Complex, Mumbai, India
| | - H Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Kolkata, India; Homi Bhabha National Institute, Training School Complex, Mumbai, India.
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4
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Mehrafrooz B, Yu L, Pandey L, Siwy ZS, Wanunu M, Aksimentiev A. Electro-osmotic Flow Generation via a Sticky Ion Action. ACS NANO 2024; 18:17521-17533. [PMID: 38832758 PMCID: PMC11233251 DOI: 10.1021/acsnano.4c00829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Selective transport of ions through nanometer-sized pores is fundamental to cell biology and central to many technological processes such as water desalination and electrical energy storage. Conventional methods for generating ion selectivity include placement of fixed electrical charges at the inner surface of a nanopore through either point mutations in a protein pore or chemical treatment of a solid-state nanopore surface, with each nanopore type requiring a custom approach. Here, we describe a general method for transforming a nanoscale pore into a highly selective, anion-conducting channel capable of generating a giant electro-osmotic effect. Our molecular dynamics simulations and reverse potential measurements show that exposure of a biological nanopore to high concentrations of guanidinium chloride renders the nanopore surface positively charged due to transient binding of guanidinium cations to the protein surface. A comparison of four biological nanopores reveals the relationship between ion selectivity, nanopore shape, composition of the nanopore surface, and electro-osmotic flow. Guanidinium ions are also found to produce anion selectivity and a giant electro-osmotic flow in solid-state nanopores via the same mechanism. Our sticky-ion approach to generate electro-osmotic flow can have numerous applications in controlling molecular transport at the nanoscale and for detection, identification, and sequencing of individual proteins.
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Affiliation(s)
- Behzad Mehrafrooz
- Center for Biophysics and Quantitative Biology, 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
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Luning Yu
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Laxmi Pandey
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
| | - Zuzanna S Siwy
- Department of Physics, University of California at Irvine, Irvine, California 92697, United States
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, United States
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Aleksei Aksimentiev
- Center for Biophysics and Quantitative Biology, 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
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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5
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Mondal R, Vaissier Welborn V. Dynamics accelerate the kinetics of ion diffusion through channels: Continuous-time random walk models beyond the mean field approximation. J Chem Phys 2024; 160:144109. [PMID: 38597306 DOI: 10.1063/5.0188469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/14/2024] [Indexed: 04/11/2024] Open
Abstract
Ion channels are proteins that play a significant role in physiological processes, including neuronal excitability and signal transduction. However, the precise mechanisms by which these proteins facilitate ion diffusion through cell membranes are not well understood. This is because experimental techniques to characterize ion channel activity operate on a time scale too large to understand the role of the various protein conformations on diffusion. Meanwhile, computational approaches operate on a time scale too short to rationalize the observed behavior at the microscopic scale. In this paper, we present a continuous-time random walk model that aims to bridge the scales between the atomistic models of ion channels and the experimental measurement of their conductance. We show how diffusion slows down in complex systems by using 3D lattices that map out the pore geometry of two channels: Nav1.7 and gramicidin. We also introduce spatial and dynamic site disorder to account for system heterogeneity beyond the mean field approximation. Computed diffusion coefficients show that an increase in spatial disorder slows down diffusion kinetics, while dynamic disorder has the opposite effect. Our results imply that microscopic or phenomenological models based on the potential of mean force data overlook the functional importance of protein dynamics on ion diffusion through channels.
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Affiliation(s)
- Ronnie Mondal
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, USA
| | - Valerie Vaissier Welborn
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, USA
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6
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Xu J, Zhang H, Chen D, Xu K, Li Z, Wu H, Geng X, Wei X, Wu J, Cui W, Wei S. Looking for a Beam of Light to Heal Chronic Pain. J Pain Res 2024; 17:1091-1105. [PMID: 38510563 PMCID: PMC10953534 DOI: 10.2147/jpr.s455549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 03/05/2024] [Indexed: 03/22/2024] Open
Abstract
Chronic pain (CP) is a leading cause of disability and a potential factor that affects biological processes, family relationships, and self-esteem of patients. However, the need for treatment of CP is presently unmet. Current methods of pain management involve the use of drugs, but there are different degrees of concerning side effects. At present, the potential mechanisms underlying CP are not completely clear. As research progresses and novel therapeutic approaches are developed, the shortcomings of current pain treatment methods may be overcome. In this review, we discuss the retinal photoreceptors and brain regions associated with photoanalgesia, as well as the targets involved in photoanalgesia, shedding light on its potential underlying mechanisms. Our aim is to provide a foundation to understand the mechanisms underlying CP and develop light as a novel analgesic treatment has its biological regulation principle for CP. This approach may provide an opportunity to drive the field towards future translational, clinical studies and support pain drug development.
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Affiliation(s)
- Jialing Xu
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Hao Zhang
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Dan Chen
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Kaiyong Xu
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Zifa Li
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Hongyun Wu
- Department of Neurology, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Xiwen Geng
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Xia Wei
- NMPA Key Laboratory for Research and Evaluation of Generic Drugs, Shandong Institute for Food and Drug Control, Ji’nan, Shandong, People’s Republic of China
| | - Jibiao Wu
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Wenqiang Cui
- Department of Neurology, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
| | - Sheng Wei
- The Key Laboratory of Traditional Chinese Medicine Classic Theory of Ministry of Education, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
- Chinese Medicine and Brain Science Interdisciplinary Research Institute, Shandong University of Traditional Chinese Medicine, Ji’nan, Shandong, People’s Republic of China
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7
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Han D, Jin X, Li Y, He W, Ai X, Yang Y, Zhang N, Zhao M, Zhou KG. Ultrahigh Lithium Selective Transport in Two-Dimensional Confined Ice. J Phys Chem Lett 2024; 15:2375-2383. [PMID: 38393886 DOI: 10.1021/acs.jpclett.3c03445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Inspired by selective ion transport in biological membrane proteins, researchers developed artificial ion channels that sieve monovalent cations, catering to the increasing lithium demand. In this work, we engineered an ion transport channel based on the confined ice within two-dimensional (2D) capillaries and found that the permselectivity of monovalent cations depends on the anisotropy of the confined ice. Particularly, the 2D confined ice showed an anomalous lithium selective transport along the (002) direction in the vermiculite capillary, with the Li+/Na+ and Li+/K+ permselectivity reaching up to 556 ± 86 and 901 ± 172, respectively, superior to most ion-selective channels. However, the 2D confined ice along the (100) direction showed less Li+ permselectivity. Additionally, the anisotropy of 2D confined ice can be tuned by adjusting the interlayer spacing. By providing insights into the ion transport in the 2D confined ice, our work may inspire more design of monovalent ion-selective channels for efficient lithium separation.
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Affiliation(s)
- Dong Han
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Xiaorui Jin
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - YuHao Li
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Weijun He
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Xinyu Ai
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Yongan Yang
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Ning Zhang
- School of Chemical Engineering, Ocean and Life Sciences, Dalian University of Technology, Panjin 124221, China
| | - Min Zhao
- College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Kai-Ge Zhou
- Institute of Molecular Plus, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
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8
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Das A, Bysack A, Raghuraman H. Cholesterol modulates the structural dynamics of the paddle motif loop of KvAP voltage sensor. Curr Res Struct Biol 2024; 7:100137. [PMID: 38500801 PMCID: PMC10945132 DOI: 10.1016/j.crstbi.2024.100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/20/2024] Open
Abstract
KvAP is a prokaryotic Kv channel, which has been widely used as a model system to understand voltage- and lipid-dependent gating mechanisms. In phospholipid membranes, the KvAP-VSD adopts the activated/'Up' conformation, whereas the presence of non-phospholipids in membranes favours the structural transition to resting/'Down' state. The S3b-S4 paddle motif loop of KvAP-VSD is functionally important as this participates in protein-protein interactions and is the target for animal toxins. In this study, we have monitored the modulatory role of cholesterol - the physiologically-relevant non-phospholipid - on the organization and dynamics of the S3b-S4 loop of the isolated KvAP-VSD in membranes by site-directed fluorescence approaches using the environmental sensitivity of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine (NBD) fluorescence. Our results show that cholesterol alters the dynamic nature (rotational and hydration dynamics) of S3b-S4 loop in a segmental fashion, i.e., the residues 110 to 114 and 115 to 117 behave differently in the presence of cholesterol, which is accompanied by considerable change in conformational heterogeneity. Further, quantitative depth measurements using the parallax quenching method reveal that the sensor loop is located at the shallow interfacial region of cholesterol-containing membranes, suggesting that the sensor loop organization is not directly correlated with S4 helix movement. Our results clearly show that cholesterol-induced changes in bilayer properties may not be the predominant factor for the sensor loop's altered structural dynamics, but can be attributed to the conformational change of the KvAP-VSD in cholesterol-containing membranes. Overall, these results are relevant for gating mechanisms, particularly the lipid-dependent gating, of Kv channels in membranes.
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Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - Arpan Bysack
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
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9
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Chen YN, Liu YZ, Sun Q. The Molecular Mechanism of Ion Selectivity in Nanopores. Molecules 2024; 29:853. [PMID: 38398605 PMCID: PMC10891634 DOI: 10.3390/molecules29040853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/03/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
Ion channels exhibit strong selectivity for specific ions over others under electrochemical potentials, such as KcsA for K+ over Na+. Based on the thermodynamic analysis, this study is focused on exploring the mechanism of ion selectivity in nanopores. It is well known that ions must lose part of their hydration layer to enter the channel. Therefore, the ion selectivity of a channel is due to the rearrangement of water molecules when entering the nanopore, which may be related to the hydrophobic interactions between ions and channels. In our recent works on hydrophobic interactions, with reference to the critical radius of solute (Rc), it was divided into initial and hydrophobic solvation processes. Additionally, the different dissolved behaviors of solutes in water are expected in various processes, such as dispersed and accumulated distributions in water. Correspondingly, as the ion approaches the nanopore, there seems to exist the "repulsive" or "attractive" forces between them. In the initial process (
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Affiliation(s)
| | | | - Qiang Sun
- Key Laboratory of Orogenic Belts and Crustal Evolution, The School of Earth and Space Sciences, Ministry of Education, Peking University, Beijing 100871, China; (Y.-N.C.); (Y.-Z.L.)
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10
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Ngo K, Yarov-Yarovoy V, Clancy CE, Vorobyov I. Harnessing AlphaFold to reveal state secrets: Prediction of hERG closed and inactivated states. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.27.577468. [PMID: 38352360 PMCID: PMC10862728 DOI: 10.1101/2024.01.27.577468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
To design safe, selective, and effective new therapies, there must be a deep understanding of the structure and function of the drug target. One of the most difficult problems to solve has been resolution of discrete conformational states of transmembrane ion channel proteins. An example is KV11.1 (hERG), comprising the primary cardiac repolarizing current, IKr. hERG is a notorious drug anti-target against which all promising drugs are screened to determine potential for arrhythmia. Drug interactions with the hERG inactivated state are linked to elevated arrhythmia risk, and drugs may become trapped during channel closure. However, the structural details of multiple conformational states have remained elusive. Here, we guided AlphaFold2 to predict plausible hERG inactivated and closed conformations, obtaining results consistent with myriad available experimental data. Drug docking simulations demonstrated hERG state-specific drug interactions aligning well with experimental results, revealing that most drugs bind more effectively in the inactivated state and are trapped in the closed state. Molecular dynamics simulations demonstrated ion conduction that aligned with earlier studies. Finally, we identified key molecular determinants of state transitions by analyzing interaction networks across closed, open, and inactivated states in agreement with earlier mutagenesis studies. Here, we demonstrate a readily generalizable application of AlphaFold2 as a novel method to predict discrete protein conformations and novel linkages from structure to function.
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Affiliation(s)
- Khoa Ngo
- Biophysics Graduate Group, University of California, Davis, CA
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Center for Precision Medicine and Data Science, University of California, Davis, CA
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Department of Anesthesiology and Pain Medicine, University of California, Davis, CA
| | - Colleen E. Clancy
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Department of Pharmacology, University of California, Davis, CA
- Center for Precision Medicine and Data Science, University of California, Davis, CA
| | - Igor Vorobyov
- Department of Physiology and Membrane Biology, University of California, Davis, CA
- Department of Pharmacology, University of California, Davis, CA
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11
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Mehrafrooz B, Yu L, Siwy Z, Wanunu M, Aksimentiev A. Electro-Osmotic Flow Generation via a Sticky Ion Action. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.14.571673. [PMID: 38168277 PMCID: PMC10760089 DOI: 10.1101/2023.12.14.571673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Selective transport of ions through nanometer-sized pores is fundamental to cell biology and central to many technological processes such as water desalination and electrical energy storage. Conventional methods for generating ion selectivity include placement of fixed electrical charges at the inner surface of a nanopore through either point mutations in a protein pore or chemical treatment of a solid-state nanopore surface, with each nanopore type requiring a custom approach. Here, we describe a general method for transforming a nanoscale pore into a highly selective, anion-conducting channel capable of generating a giant electro-osmotic effect. Our molecular dynamics simulations and reverse potential measurements show that exposure of a biological nanopore to high concentrations of guanidinium chloride renders the nanopore surface positively charged due to transient binding of guanidinium cations to the protein surface. A comparison of four biological nanopores reveals the relationship between ion selectivity, nanopore shape, composition of the nanopore surface, and electro-osmotic flow. Remarkably, guanidinium ions are also found to produce anion selectivity and a giant electro-osmotic flow in solid-state nanopores via the same mechanism. Our sticky-ion approach to generate electro-osmotic flow can have numerous applications in controlling molecular transport at the nanoscale and for detection, identification, and sequencing of individual proteins.
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Affiliation(s)
- Behzad Mehrafrooz
- Center for Biophysics and Quantitative Biology
- Beckman Institute for Advanced Science and Technology
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Luning Yu
- Department of Physics, Northeastern University, Boston, MA 02115 USA
| | - Zuzanna Siwy
- Department of Physics, University of California at Irvine, Irvine, CA 92697, USA
| | - Meni Wanunu
- Department of Physics, Northeastern University, Boston, MA 02115 USA
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
| | - Aleksei Aksimentiev
- Center for Biophysics and Quantitative Biology
- Beckman Institute for Advanced Science and Technology
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois
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12
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Phan LX, Owji AP, Yang T, Crain J, Sansom MSP, Tucker SJ. Electronic Polarizability Tunes the Function of the Human Bestrophin 1 Cl - Channel. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567055. [PMID: 38014257 PMCID: PMC10680768 DOI: 10.1101/2023.11.14.567055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Mechanisms of anion permeation within ion channels and nanopores remain poorly understood. Recent cryo-electron microscopy structures of the human bestrophin 1 chloride channel (hBest1) provide an opportunity to evaluate ion interactions predicted by molecular dynamics (MD) simulations against experimental observations. We implement the fully polarizable forcefield AMOEBA in MD simulations of open and partially-open states of the hBest1. The AMOEBA forcefield models multipole moments up to the quadrupole; therefore, it captures induced dipole and anion- π interactions. By including polarization we demonstrate the key role that aromatic residues play in ion permeation and the functional advantages of pore asymmetry within the highly conserved hydrophobic neck of the pore. We establish that these only arise when electronic polarization is included in the molecular models. We also show that Cl - permeation in this region can be achieved through hydrophobic solvation concomitant with partial ion dehydration, which is compensated for by the formation of contacts with the edge of the phenylalanine ring. Furthermore, we demonstrate how polarizable simulations can help determine the identity of ion-like densities within high-resolution cryo-EM structures. Crucially, neglecting polarization in simulation of these systems results in the localization of Cl - at positions that do not correspond with their experimentally resolved location. Overall, our results demonstrate the importance of including electronic polarization in realistic and physically accurate models of biological systems. Statement of Significance Ion channels are nanoscale protein pores that enable the selective passage of charged ions across cell membranes. Understanding the underlying mechanisms for selective anion permeation through such pores remains a challenge. To simulate their behavior efficiently in silico , fixed charge models are typically employed. However, this approach is insufficient for the study of anions. Here, we use simulations with explicit treatment of electrostatics to investigate the interactions of chloride ions in the human bestrophin 1 channel. We find that electronic polarization tunes the state of the channel and affects the interactions of chloride ions thereby revealing a mechanism for permeation. Furthermore, these simulations can be used to resolve experimental ambiguity in ion-like densities from cryo-EM structures.
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13
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Wawrzkiewicz-Jałowiecka A, Fuliński A. Brownian Aging as One of the Mechanistic Components That Shape the Single-Channel Ionic Currents through Biological and Synthetic Membranes. MEMBRANES 2023; 13:879. [PMID: 37999365 PMCID: PMC10673163 DOI: 10.3390/membranes13110879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/26/2023] [Accepted: 11/08/2023] [Indexed: 11/25/2023]
Abstract
Semipermeable membranes enable the separation of a given system from its environment. In biological terms, they are responsible for cells' identity. In turn, the functioning of ion channels is crucial for the control of ionic fluxes across the membranes and, consequently, for the exchange of chemical and electrical signals. This paper presents a model and simulations of currents through ionic nanochannels in an attempt to better understand the physical mechanism(s) of open/closed (O/C) sequences, i.e., random interruptions of ionic flows through channels observed in all known biochannels and in some synthetic nanopores. We investigate whether aging, i.e., the changes in Brownian motion characteristics with the lapse of time, may be at least one of the sources of the O/C sequences (in addition to the gating machinery in biochannels). The simulations based on the approximated nanostructure of ion channels confirm this postulation. The results also show the possibility of changing the O/C characteristics through an appropriate alteration of the channel surroundings. This observation may be valuable in technical uses of nanochannels in synthetic membranes and allow for a better understanding of the reason for the differences between the biochannels' activity in diverse biological membranes. Proposals of experimental verification of this aging O/C hypothesis are also presented.
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Affiliation(s)
- Agata Wawrzkiewicz-Jałowiecka
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice, Poland
| | - Andrzej Fuliński
- Institute of Theoretical Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland
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14
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Stevens MJ, Rempe SLB. Binding of carboxylate and water to monovalent cations. Phys Chem Chem Phys 2023; 25:29881-29893. [PMID: 37889481 DOI: 10.1039/d3cp04200f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
The interactions of carboxylate anions with water and cations are important for a wide variety of systems, both biological and synthetic. To gain insight on properties of the local complexes, we apply density functional theory, to treat the complex electrostatic interactions, and investigate mixtures with varied numbers of carboxylate anions (acetate) and waters binding to monovalent cations, Li+, Na+ and K+. The optimal structure with overall lowest free energy contains two acetates and two waters such that the cation is four-fold coordinated, similar to structures found earlier for pure water or pure carboxylate ligands. More generally, the complexes with two acetates have the lowest free energy. In transitioning from the overall optimal state, exchanging an acetate for water has a lower free energy barrier than exchanging water for an acetate. In most cases, the carboxylates are monodentate and in the first solvation shell. As water is added to the system, hydrogen bonding between waters and carboxylate O atoms further stabilizes monodentate structures. These structures, which have strong electrostatic interactions that involve hydrogen bonds of varying strength, are significantly polarized, with ChelpG partial charges that vary substantially as the bonding geometry varies. Overall, these results emphasize the increasing importance of water as a component of binding sites as the number of ligands increases, thus affecting the preferential solvation of specific metal ions and clarifying Hofmeister effects. Finally, structural analysis correlated with free energy analysis supports the idea that binding to more than the preferred number of carboxylates under architectural constraints are a key to ion transport.
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Affiliation(s)
- Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
| | - Susan L B Rempe
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
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15
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Silva MP, Rodrigues CG, Machado DC, Nogueira RA. Long-term memory in Staphylococcus aureus α-hemolysin ion channel kinetics. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:661-671. [PMID: 37542583 DOI: 10.1007/s00249-023-01675-8] [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: 06/20/2022] [Revised: 07/03/2023] [Accepted: 07/20/2023] [Indexed: 08/07/2023]
Abstract
The kinetics of an ion channel are classically understood as a random process. However, studies have shown that in complex ion channels, formed by multiple subunits, this process can be deterministic, presenting long-term memory. Staphylococcus aureus α-hemolysin (α-HL) is a toxin that acts as the major factor in Staphylococcus aureus virulence. α-HL is a water-soluble protein capable of forming ion channels into lipid bilayers, by insertion of an amphipathic β-barrel. Here, the α-HL was used as an experimental model to study memory in ion channel kinetics. We applied the approximate entropy (ApEn) approach to analyze randomness and the Detrended Fluctuation Analysis (DFA) to investigate the existence of long memory in α-HL channel kinetics. Single-channel currents were measured through experiments with α-HL channels incorporated in planar lipid bilayers. All experiments were carried out under the following conditions: 1 M NaCl solution, pH 4.5; transmembrane potential of + 40 mV and temperature 25 ± 1 °C. Single-channel currents were recorded in real-time in the memory of a microcomputer coupled to an A/D converter and a patch-clamp amplifier. The conductance value of the α-HL channels was 0.82 ± 0.0025 nS (n = 128). The DFA analysis showed that the kinetics of α-HL channels presents long-term memory ([Formula: see text] = 0.63 ± 0.04). The ApEn outcomes showed low complexity to dwell times when open (ApEno = 0.5514 ± 0.28) and closed (ApEnc = 0.1145 ± 0.08), corroborating the results of the DFA method.
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Affiliation(s)
- M P Silva
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil
| | - C G Rodrigues
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Recife, Pernambuco, Brazil
| | - D C Machado
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Recife, Pernambuco, Brazil
| | - R A Nogueira
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil.
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16
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Colla T, Telles IM, Arfan M, Dos Santos AP, Levin Y. Spiers Memorial Lecture: Towards understanding of iontronic systems: electroosmotic flow of monovalent and divalent electrolyte through charged cylindrical nanopores. Faraday Discuss 2023; 246:11-46. [PMID: 37395363 DOI: 10.1039/d3fd00062a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
In many practical applications, ions are the primary charge carrier and must move through either semipermeable membranes or through pores, which mimic ion channels in biological systems. In analogy to electronic devices, the "iontronic" ones use electric fields to induce the charge motion. However, unlike the electrons that move through a conductor, motion of ions is usually associated with simultaneous solvent flow. A study of electroosmotic flow through narrow pores is an outstanding challenge that lies at the interface of non-equilibrium statistical mechanics and fluid dynamics. In this paper, we will review recent works that use dissipative particle dynamics simulations to tackle this difficult problem. We will also present a classical density functional theory (DFT) based on the hypernetted-chain approximation (HNC), which allows us to calculate the velocity of electroosmotic flows inside nanopores containing 1 : 1 or 2 : 1 electrolyte solution. The theoretical results will be compared with simulations. In simulations, the electrostatic interactions are treated using the recently introduced pseudo-1D Ewald summation method. The zeta potentials calculated from the location of the shear plane of a pure solvent are found to agree reasonably well with the Smoluchowski equation. However, the quantitative structure of the fluid velocity profiles deviates significantly from the predictions of the Smoluchowski equation in the case of charged pores with 2 : 1 electrolyte. For low to moderate surface charge densities, the DFT allows us to accurately calculate the electrostatic potential profiles and the zeta potentials inside the nanopores. For pores with 1 : 1 electrolyte, the agreement between theory and simulation is particularly good for large ions, for which steric effects dominate over the ionic electrostatic correlations. The electroosmotic flow is found to depend very strongly on the ionic radii. In the case of pores containing 2 : 1 electrolyte, we observe a reentrant transition in which the electroosmotic flow first reverses and then returns to normal as the surface change density of the pore is increased.
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Affiliation(s)
- Thiago Colla
- Instituto de Física, Universidade Federal de Ouro Preto, Ouro Preto, MG, 35400-000, Brazil.
| | - Igor M Telles
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, Porto Alegre, RS, CEP 91501-970, Brazil.
| | - Muhammad Arfan
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, Porto Alegre, RS, CEP 91501-970, Brazil.
| | - Alexandre P Dos Santos
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, Porto Alegre, RS, CEP 91501-970, Brazil.
| | - Yan Levin
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, Porto Alegre, RS, CEP 91501-970, Brazil.
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17
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Maqoud F, Tricarico D, Mallamaci R, Orlando A, Russo F. The Role of Ion Channels in Functional Gastrointestinal Disorders (FGID): Evidence of Channelopathies and Potential Avenues for Future Research and Therapeutic Targets. Int J Mol Sci 2023; 24:11074. [PMID: 37446251 DOI: 10.3390/ijms241311074] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023] Open
Abstract
Several gastrointestinal (GI) tract abnormalities, including visceral hypersensitivity, motility, and intestinal permeability alterations, have been implicated in functional GI disorders (FGIDs). Ion channels play a crucial role in all the functions mentioned above. Hormones and natural molecules modulate these channels and represent targets of drugs and bacterial toxins. Mutations and abnormal functional expression of ion channel subunits can lead to diseases called channelopathies. These channelopathies in gastroenterology are gaining a strong interest, and the evidence of co-relationships is increasing. In this review, we describe the correlation status between channelopathies and FGIDs. Different findings are available. Among others, mutations in the ABCC7/CFTR gene have been described as a cause of constipation and diarrhea. Mutations of the SCN5A gene are instead associated with irritable bowel syndrome. In contrast, mutations of the TRPV1 and TRPA genes of the transient receptor potential (TRP) superfamily manifest hypersensitivity and visceral pain in sensory nerves. Recently, mice and humans affected by Cantu syndrome (CS), which is associated with the mutations of the KCNJ8 and ABCC9 genes encoding for the Kir6.1 and SUR2 subunits, showed dysfunction of contractility throughout the intestine and death in the mice after the weaning on solid food. The discovery of a correlation between channelopathies and FIGD opens new avenues for discovering new direct drug targets for specific channelopathies, leading to significant implications for diagnosing and treating functional GI diseases.
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Affiliation(s)
- Fatima Maqoud
- Functional Gastrointestinal Disorders Research Group, National Institute of Gastroenterology IRCCS "Saverio de Bellis", Castellana Grotte, 70013 Bari, Italy
| | - Domenico Tricarico
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Rosanna Mallamaci
- Department of Biosciences, Biotechnologies and Environment University of Bari Aldo Moro, 70125 Bari, Italy
| | - Antonella Orlando
- Functional Gastrointestinal Disorders Research Group, National Institute of Gastroenterology IRCCS "Saverio de Bellis", Castellana Grotte, 70013 Bari, Italy
| | - Francesco Russo
- Functional Gastrointestinal Disorders Research Group, National Institute of Gastroenterology IRCCS "Saverio de Bellis", Castellana Grotte, 70013 Bari, Italy
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18
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Alberini G, Alexis Paz S, Corradi B, Abrams CF, Benfenati F, Maragliano L. Molecular Dynamics Simulations of Ion Permeation in Human Voltage-Gated Sodium Channels. J Chem Theory Comput 2023; 19:2953-2972. [PMID: 37116214 DOI: 10.1021/acs.jctc.2c00990] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
The recent determination of cryo-EM structures of voltage-gated sodium (Nav) channels has revealed many details of these proteins. However, knowledge of ionic permeation through the Nav pore remains limited. In this work, we performed atomistic molecular dynamics (MD) simulations to study the structural features of various neuronal Nav channels based on homology modeling of the cryo-EM structure of the human Nav1.4 channel and, in addition, on the recently resolved configuration for Nav1.2. In particular, single Na+ permeation events during standard MD runs suggest that the ion resides in the inner part of the Nav selectivity filter (SF). On-the-fly free energy parametrization (OTFP) temperature-accelerated molecular dynamics (TAMD) was also used to calculate two-dimensional free energy surfaces (FESs) related to single/double Na+ translocation through the SF of the homology-based Nav1.2 model and the cryo-EM Nav1.2 structure, with different realizations of the DEKA filter domain. These additional simulations revealed distinct mechanisms for single and double Na+ permeation through the wild-type SF, which has a charged lysine in the DEKA ring. Moreover, the configurations of the ions in the SF corresponding to the metastable states of the FESs are specific for each SF motif. Overall, the description of these mechanisms gives us new insights into ion conduction in human Nav cryo-EM-based and cryo-EM configurations that could advance understanding of these systems and how they differ from potassium and bacterial Nav channels.
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Affiliation(s)
- Giulio Alberini
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Sergio Alexis Paz
- Departamento de Química Teórica y Computacional, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Fisicoquímica de Córdoba (INFIQC), X5000HUA Córdoba, Argentina
| | - Beatrice Corradi
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- Department of Experimental Medicine, Università degli Studi di Genova, Viale Benedetto XV 3, 16132 Genova, Italy
| | - Cameron F Abrams
- Department of Chemical and Biological Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
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19
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Wang G, Xu L, Chen H, Liu Y, Pan P, Hou T. Recent advances in computational studies on voltage‐gated sodium channels: Drug design and mechanism studies. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2023. [DOI: 10.1002/wcms.1641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Affiliation(s)
- Gaoang Wang
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University College of Pharmaceutical Sciences, Zhejiang University Hangzhou Zhejiang China
| | - Lei Xu
- Institute of Bioinformatics and Medical Engineering School of Electrical and Information Engineering, Jiangsu University of Technology Changzhou Jiangsu China
| | - Haiyi Chen
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University College of Pharmaceutical Sciences, Zhejiang University Hangzhou Zhejiang China
| | - Yifei Liu
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University College of Pharmaceutical Sciences, Zhejiang University Hangzhou Zhejiang China
| | - Peichen Pan
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University College of Pharmaceutical Sciences, Zhejiang University Hangzhou Zhejiang China
| | - Tingjun Hou
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University College of Pharmaceutical Sciences, Zhejiang University Hangzhou Zhejiang China
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20
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Matamoros M, Ng XW, Brettmann JB, Piston DW, Nichols CG. Conformational plasticity of NaK2K and TREK2 potassium channel selectivity filters. Nat Commun 2023; 14:89. [PMID: 36609575 PMCID: PMC9822992 DOI: 10.1038/s41467-022-35756-7] [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: 05/18/2022] [Accepted: 12/23/2022] [Indexed: 01/07/2023] Open
Abstract
The K+ channel selectivity filter (SF) is defined by TxGYG amino acid sequences that generate four identical K+ binding sites (S1-S4). Only two sites (S3, S4) are present in the non-selective bacterial NaK channel, but a four-site K+-selective SF is obtained by mutating the wild-type TVGDGN SF sequence to a canonical K+ channel TVGYGD sequence (NaK2K mutant). Using single molecule FRET (smFRET), we show that the SF of NaK2K, but not of non-selective NaK, is ion-dependent, with the constricted SF configuration stabilized in high K+ conditions. Patch-clamp electrophysiology and non-canonical fluorescent amino acid incorporation show that NaK2K selectivity is reduced by crosslinking to limit SF conformational movement. Finally, the eukaryotic K+ channel TREK2 SF exhibits essentially identical smFRET-reported ion-dependent conformations as in prokaryotic K+ channels. Our results establish the generality of K+-induced SF conformational stability across the K+ channel superfamily, and introduce an approach to study manipulation of channel selectivity.
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Affiliation(s)
- Marcos Matamoros
- Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Xue Wen Ng
- Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Joshua B Brettmann
- Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Millipore-Sigma Inc., St. Louis, MO, USA
| | - David W Piston
- Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Colin G Nichols
- Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA.
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21
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Haas R, Nikel PI. Challenges and opportunities in bringing nonbiological atoms to life with synthetic metabolism. Trends Biotechnol 2023; 41:27-45. [PMID: 35786519 DOI: 10.1016/j.tibtech.2022.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 06/05/2022] [Accepted: 06/09/2022] [Indexed: 02/06/2023]
Abstract
The relatively narrow spectrum of chemical elements within the microbial 'biochemical palate' limits the reach of biotechnology, because several added-value compounds can only be produced with traditional organic chemistry. Synthetic biology offers enabling tools to tackle this issue by facilitating 'biologization' of non-canonical chemical atoms. The interplay between xenobiology and synthetic metabolism multiplies routes for incorporating nonbiological atoms into engineered microbes. In this review, we survey natural assimilation routes for elements beyond the essential biology atoms [i.e., carbon (C), hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P), and sulfur (S)], discussing how these mechanisms could be repurposed for biotechnology. Furthermore, we propose a computational framework to identify chemical elements amenable to biologization, ranking reactions suitable to build synthetic metabolism. When combined and deployed in robust microbial hosts, these approaches will offer sustainable alternatives for smart chemical production.
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Affiliation(s)
- Robert Haas
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Pablo I Nikel
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
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22
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Weak Point of SARS-CoV-2: Human and Viral Ion Channels under External Physical Fields. Int J Mol Sci 2022; 23:ijms232315185. [PMID: 36499511 PMCID: PMC9737394 DOI: 10.3390/ijms232315185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022] Open
Abstract
The ionic E-nanochannel (viroporin) is the weak point of SARS-CoV-2, the virus responsible for the (still threatening) COVID-19 since it is vital to the virus's budding and propagation. Therefore, targeting it to disable its functions ought to incapacitate, or at least weaken, the virus. The ionic currents inside this channel could be affected and disturbed by direct physical attack via the actions of external fields. The paper presents the first step towards the application of such methods in the fight against the current pandemic, numerical simulations of external fields' impact on ionic currents through viral channels. These simulations-based on the actual, detailed physical nanostructure of ionic channels, measured experimentally and reported in the literature-show that external physical fields can diminish the channel's currents and that the lower the channel's selectivity, the stronger the effect. Simulations suggest that SARS-CoV-2 E-viroporin is almost non-selective, which means that the whole virus ought to be highly vulnerable to the actions of external physical fields, much more vulnerable than the much more selective human cell ionic channels. If corroborated by experiment, this observation may result in an innovative method of dealing with the recent pandemic caused by SARS-CoV-2 and other similar viruses.
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23
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Liu J, Li X, Xu N, Han H, Li X. Role of ion channels in the mechanism of proteinuria (Review). Exp Ther Med 2022; 25:27. [PMID: 36561615 PMCID: PMC9748662 DOI: 10.3892/etm.2022.11726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/10/2022] [Indexed: 11/25/2022] Open
Abstract
Proteinuria is a common clinical manifestation of kidney diseases, such as glomerulonephritis, nephrotic syndrome, immunoglobulin A nephropathy and diabetic nephropathy. Therefore, proteinuria is considered to be a risk factor for renal dysfunction. Furthermore, proteinuria is also significantly associated with the progression of kidney diseases and increased mortality. Its occurrence is closely associated with damage to the structure of the glomerular filtration membrane. An impaired glomerular filtration membrane can affect the selective filtration function of the kidneys; therefore, several macromolecular substances, such as proteins, may pass through the filtration membrane and promote the manifestation of proteinuria. It has been reported that ion channels play a significant role in the mechanisms underlying proteinuria. Ion channel mutations or other dysfunctions have been implicated in several diseases, therefore ion channels could be used as major therapeutic targets. The mechanisms underlying the action of ion channels and ion transporters in proteinuria have been overlooked in the literature, despite their importance in identifying novel targets for treating proteinuria and delaying the progression of kidney diseases. The current review article focused on the four key ion channel groups, namely Na+, Ca2+, Cl- and K+ ion channels and the associated ion transporters.
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Affiliation(s)
- Jie Liu
- Department of Nephrology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong 261000, P.R. China
| | - Xuewei Li
- Department of Rheumatology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong 261000, P.R. China
| | - Ning Xu
- Department of Nephrology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong 261000, P.R. China
| | - Huirong Han
- Department of Anesthesiology, Weifang Medical University, Weifang, Shandong 261000, P.R. China
| | - Xiangling Li
- Department of Nephrology, Affiliated Hospital of Weifang Medical University, Weifang, Shandong 261000, P.R. China,Correspondence to: Professor Xiangling Li, Department of Nephrology, Affiliated Hospital of Weifang Medical University, 2428 Yu He Road, Weifang, Shandong 261000, P.R. China
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24
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Higgins JA, Ramos DS, Gili S, Spetea C, Kanoski S, Ha D, McDonough AA, Youn JH. Stable potassium isotopes (41K/39K) track transcellular and paracellular potassium transport in biological systems. Front Physiol 2022; 13:1016242. [PMID: 36388124 PMCID: PMC9644202 DOI: 10.3389/fphys.2022.1016242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 09/21/2022] [Indexed: 12/04/2022] Open
Abstract
As the most abundant cation in archaeal, bacterial, and eukaryotic cells, potassium (K+) is an essential element for life. While much is known about the machinery of transcellular and paracellular K transport–channels, pumps, co-transporters, and tight-junction proteins—many quantitative aspects of K homeostasis in biological systems remain poorly constrained. Here we present measurements of the stable isotope ratios of potassium (41K/39K) in three biological systems (algae, fish, and mammals). When considered in the context of our current understanding of plausible mechanisms of K isotope fractionation and K+ transport in these biological systems, our results provide evidence that the fractionation of K isotopes depends on transport pathway and transmembrane transport machinery. Specifically, we find that passive transport of K+ down its electrochemical potential through channels and pores in tight-junctions at favors 39K, a result which we attribute to a kinetic isotope effect associated with dehydration and/or size selectivity at the channel/pore entrance. In contrast, we find that transport of K+ against its electrochemical gradient via pumps and co-transporters is associated with less/no isotopic fractionation, a result that we attribute to small equilibrium isotope effects that are expressed in pumps/co-transporters due to their slower turnover rate and the relatively long residence time of K+ in the ion pocket. These results indicate that stable K isotopes may be able to provide quantitative constraints on transporter-specific K+ fluxes (e.g., the fraction of K efflux from a tissue by channels vs. co-transporters) and how these fluxes change in different physiological states. In addition, precise determination of K isotope effects associated with K+ transport via channels, pumps, and co-transporters may provide unique constraints on the mechanisms of K transport that could be tested with steered molecular dynamic simulations.
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Affiliation(s)
- John A. Higgins
- Department of Geosciences, Princeton University, Princeton, NJ, United States
- *Correspondence: John A. Higgins,
| | - Danielle Santiago Ramos
- Department of Marine and Coastal Science, Rutgers University, New Brunswick, NJ, United States
| | - Stefania Gili
- Department of Geosciences, Princeton University, Princeton, NJ, United States
| | - Cornelia Spetea
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States
| | - Scott Kanoski
- Department of Human and Evolutionary Biology, University of Southern California, Los Angeles, CA, United States
| | - Darren Ha
- Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - Alicia A. McDonough
- Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
| | - Jang H. Youn
- Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, United States
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25
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Yan P, Ke B, Fang X. Ion channels as a therapeutic target for renal fibrosis. Front Physiol 2022; 13:1019028. [PMID: 36277193 PMCID: PMC9581181 DOI: 10.3389/fphys.2022.1019028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Renal ion channel transport and electrolyte disturbances play an important role in the process of functional impairment and fibrosis in the kidney. It is well known that there are limited effective drugs for the treatment of renal fibrosis, and since a large number of ion channels are involved in the renal fibrosis process, understanding the mechanisms of ion channel transport and the complex network of signaling cascades between them is essential to identify potential therapeutic approaches to slow down renal fibrosis. This review summarizes the current work of ion channels in renal fibrosis. We pay close attention to the effect of cystic fibrosis transmembrane conductance regulator (CFTR), transmembrane Member 16A (TMEM16A) and other Cl− channel mediated signaling pathways and ion concentrations on fibrosis, as well as the various complex mechanisms for the action of Ca2+ handling channels including Ca2+-release-activated Ca2+ channel (CRAC), purinergic receptor, and transient receptor potential (TRP) channels. Furthermore, we also focus on the contribution of Na+ transport such as epithelial sodium channel (ENaC), Na+, K+-ATPase, Na+-H+ exchangers, and K+ channels like Ca2+-activated K+ channels, voltage-dependent K+ channel, ATP-sensitive K+ channels on renal fibrosis. Proposed potential therapeutic approaches through further dissection of these mechanisms may provide new therapeutic opportunities to reduce the burden of chronic kidney disease.
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26
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Berselli A, Alberini G, Benfenati F, Maragliano L. Computational study of ion permeation through claudin-4 paracellular channels. Ann N Y Acad Sci 2022; 1516:162-174. [PMID: 35811406 PMCID: PMC9796105 DOI: 10.1111/nyas.14856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Claudins (Cldns) form a large family of protein homologs that are essential for the assembly of paracellular tight junctions (TJs), where they form channels or barriers with tissue-specific selectivity for permeants. In contrast to several family members whose physiological role has been identified, the function of claudin 4 (Cldn4) remains elusive, despite experimental evidence suggesting that it can form anion-selective TJ channels in the renal epithelium. Computational approaches have recently been employed to elucidate the molecular basis of Cldns' function, and hence could help in clarifying the role of Cldn4. In this work, we use structural modeling and all-atom molecular dynamics simulations to transfer two previously introduced structural models of Cldn-based paracellular complexes to Cldn4 to reproduce a paracellular anion channel. Free energy calculations for ionic transport through the pores allow us to establish the thermodynamic properties driving the ion-selectivity of the structures. While one model shows a cavity permeable to chloride and repulsive to cations, the other forms barrier to the passage of all the major physiological ions. Furthermore, our results confirm the charge selectivity role of the residue Lys65 in the first extracellular loop of the protein, rationalizing Cldn4 control of paracellular permeability.
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Affiliation(s)
- Alessandro Berselli
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,Department of Experimental MedicineUniversità degli Studi di GenovaGenovaItaly
| | - Giulio Alberini
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,IRCCS Ospedale Policlinico San MartinoGenovaItaly
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,IRCCS Ospedale Policlinico San MartinoGenovaItaly
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe)Istituto Italiano di TecnologiaGenovaItaly,Department of Life and Environmental SciencesPolytechnic University of MarcheAnconaItaly
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27
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Stevens MJ, Rempe SLB. Carboxylate binding prefers two cations to one. Phys Chem Chem Phys 2022; 24:22198-22205. [PMID: 36093927 DOI: 10.1039/d2cp03561h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Almost all studies of specific ion binding by carboxylates (-COO-) have considered only a single cation, but clustering of ions and ligands is a common phenomenon. We apply density functional theory to investigate how variations in the number of acetate ligands in binding to two monovalent cations affects ion binding preferences. We study a series of monovalent (Li+, Na+, K+, Cs+) ions relevant to experimental work on many topics, including ion channels, battery storage, water purification and solar cells. We find that the preferred optimal structure has 3 acetates except for Cs+, which has 2 acetates. The optimal coordination of the cation by the carboxylate O atoms is 4 for both Na+ and K+, and 3 for Li+ and Cs+. There is a 4-fold coordination minimum just a few kcal mol-1 higher than the optimal 3-fold structure for Li+. For two cations, multiple minima occur in the vicinity of the lowest free energy state. We find that, for Li, Na and K, the preferred optimal structure with two cations is favored over a mixture of single cation complexes, providing a basis for understanding ionic cluster formation that is relevant for engineering proteins and other materials for rapid, selective ion transport.
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Affiliation(s)
- Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA.
| | - Susan L B Rempe
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87185, USA. .,CBRN Defense and Energy Technologies, Sandia National Laboratories, Albuquerque, NM, 87185, USA.
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28
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Ahrari S, Ozturk TN, D'Avanzo N. ION BEHAVIOUR IN THE SELECTIVITY FILTER OF HCN1 CHANNELS. Biophys J 2022; 121:2206-2218. [PMID: 35474263 DOI: 10.1016/j.bpj.2022.04.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/20/2022] [Accepted: 04/20/2022] [Indexed: 11/26/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated channels (HCNs) are responsible for the generation of pacemaker currents (If or Ih) in cardiac and neuronal cells. Despite the overall structural similarity to voltage-gated potassium (Kv) channels, HCNs show much lower selectivity for K+ over Na+ ions. This increased permeability to Na+ is critical to their role in membrane depolarization. HCNs can also select between Na+ and Li+ ions. Here we investigate the unique ion selectivity properties of HCNs using molecular dynamics simulations. Our simulations suggest that the HCN1 pore is flexible and dilated compared to Kv channels with only one stable ion binding site within the selectivity filter. We also observe that ion coordination and hydration differ within the HCN1 selectivity filter compared to those in Kv and CNG channels. Additionally, the C358T mutation further stabilizes the symmetry of the binding site and provides a more fit space for ion coordination, particularly for Li+. STATEMENT OF SIGNIFICANCE: Hyperpolarization-activated cyclic-nucleotide gated (HCN) channels represent the molecular correlate of the currents If or Ih in cardiomyocytes and neurons. Here we study the unique low conductance and semi-selective properties of HCNs. The conductance and selectivity mechanisms of ion channels are tightly associated with their physiological role and contribute to the specific properties of the excitable cells in which they are expressed.
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Affiliation(s)
- Sajjad Ahrari
- Département de pharmacologie et physiologie, Université de Montréal, 2960 Chemin de la Tour, Montréal, Canada, H3T 1J4
| | - Tugba N Ozturk
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, 223 McDonnell Sciences Building, St. Louis, US, 63110; Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, Maryland, 20814
| | - Nazzareno D'Avanzo
- Département de pharmacologie et physiologie, Université de Montréal, 2960 Chemin de la Tour, Montréal, Canada, H3T 1J4.
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29
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Bauer D, Wissmann J, Moroni A, Thiel G, Hamacher K. Weak Cation Selectivity in HCN Channels Results From K +-Mediated Release of Na + From Selectivity Filter Binding Sites. FUNCTION (OXFORD, ENGLAND) 2022; 3:zqac019. [PMID: 36156894 PMCID: PMC9492253 DOI: 10.1093/function/zqac019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 01/07/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels generate the pacemaker current which plays an important role in the timing of various biological processes like the heart beat. We used umbrella sampling to explore the potential of mean force for the conduction of potassium and sodium through the open HCN4 pore. Our data explain distinct functional features like low unitary conductance and weak selectivity as a result of high energetic barriers inside the selectivity filter of this channel. They exceed the 3-5 kJ/mol threshold which is presumed as maximal barrier for diffusion-limited conductance. Furthermore, simulations provide a thermodynamic explanation for the weak cation selectivity of HCN channels that contain only two ion binding sites in the selectivity filter (SF). We find that sodium ions bind more strongly to the SF than potassium and are easier released by binding of potassium than of another sodium. Hence ion transport and selectivity in HCN channels is not determined by the same mechanism as in potassium-selective channels; it rather relies on sodium as a weak blocker that can only be released by potassium.
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Affiliation(s)
- Daniel Bauer
- Department of Biology and Centre for Synthetic Biology, TU Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
| | - Jan Wissmann
- Department of Physics, TU Darmstadt, Schlossgartenstrasse 7, 64289 Darmstadt, Germany
| | - Anna Moroni
- Department of Biosciences, University of Milan, via Celoria 26, 20133 Milan, Italy
| | | | - Kay Hamacher
- Department of Biology and Centre for Synthetic Biology, TU Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany,Department of Physics, TU Darmstadt, Schlossgartenstrasse 7, 64289 Darmstadt, Germany
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30
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Picci G, Marchesan S, Caltagirone C. Ion Channels and Transporters as Therapeutic Agents: From Biomolecules to Supramolecular Medicinal Chemistry. Biomedicines 2022; 10:biomedicines10040885. [PMID: 35453638 PMCID: PMC9032600 DOI: 10.3390/biomedicines10040885] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/07/2022] [Accepted: 04/09/2022] [Indexed: 12/13/2022] Open
Abstract
Ion channels and transporters typically consist of biomolecules that play key roles in a large variety of physiological and pathological processes. Traditional therapies include many ion-channel blockers, and some activators, although the exact biochemical pathways and mechanisms that regulate ion homeostasis are yet to be fully elucidated. An emerging area of research with great innovative potential in biomedicine pertains the design and development of synthetic ion channels and transporters, which may provide unexplored therapeutic opportunities. However, most studies in this challenging and multidisciplinary area are still at a fundamental level. In this review, we discuss the progress that has been made over the last five years on ion channels and transporters, touching upon biomolecules and synthetic supramolecules that are relevant to biological use. We conclude with the identification of therapeutic opportunities for future exploration.
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Affiliation(s)
- Giacomo Picci
- Chemical and Geological Sciences Department, University of Cagliari, 09042 Cagliari, Italy;
| | - Silvia Marchesan
- Chemical and Pharmaceutical Sciences Department, University of Trieste, 34127 Trieste, Italy
- Correspondence: (S.M.); (C.C.)
| | - Claudia Caltagirone
- Chemical and Geological Sciences Department, University of Cagliari, 09042 Cagliari, Italy;
- Correspondence: (S.M.); (C.C.)
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31
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Matevosyan A, Allahverdyan AE. Nonequilibrium, weak-field-induced cyclotron motion: A mechanism for magnetobiology. Phys Rev E 2021; 104:064407. [PMID: 35030908 DOI: 10.1103/physreve.104.064407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 11/17/2021] [Indexed: 11/07/2022]
Abstract
There is a long-time quest for understanding physical mechanisms of weak magnetic field interaction with biological matter. Two factors impeded the development of such mechanisms: first, a high (room) temperature of a cellular environment, where a weak, static magnetic field induces a (classically) zero equilibrium response. Second, the friction in the cellular environment is large, preventing a weak field to alter nonequilibrium processes such as a free diffusion of charges. Here we study a class of nonequilibrium steady states of a cellular ion in a confining potential, where the response to a (weak, homogeneous, static) magnetic field survives strong friction and thermal fluctuations. The magnetic field induces a rotational motion of the ion that proceeds with the cyclotron frequency. Such nonequilibrium states are generated by a white noise acting on the ion additionally to the nonlocal (memory-containing) friction and noise generated by an equilibrium thermal bath. The intensity of this white noise can be weak, i.e., much smaller than the thermal noise intensity.
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Affiliation(s)
- Ashot Matevosyan
- University of Cambridge, Cavendish Laboratory, 19 J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom.,Alikhanyan National Laboratory (Yerevan Physics Institute), 2 Alikhanyan Brothers street, Yerevan 0036, Armenia
| | - Armen E Allahverdyan
- Alikhanyan National Laboratory (Yerevan Physics Institute), 2 Alikhanyan Brothers street, Yerevan 0036, Armenia.,Yerevan State University, 1 A. Manoogian street, Yerevan 0025, Armenia
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32
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Bogard A, Finn PW, McKinney F, Flacau IM, Smith AR, Whiting R, Fologea D. The Ionic Selectivity of Lysenin Channels in Open and Sub-Conducting States. MEMBRANES 2021; 11:897. [PMID: 34832126 PMCID: PMC8622276 DOI: 10.3390/membranes11110897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/14/2021] [Accepted: 11/18/2021] [Indexed: 01/13/2023]
Abstract
The electrochemical gradients established across cell membranes are paramount for the execution of biological functions. Besides ion channels, other transporters, such as exogenous pore-forming toxins, may present ionic selectivity upon reconstitution in natural and artificial lipid membranes and contribute to the electrochemical gradients. In this context, we utilized electrophysiology approaches to assess the ionic selectivity of the pore-forming toxin lysenin reconstituted in planar bilayer lipid membranes. The membrane voltages were determined from the reversal potentials recorded upon channel exposure to asymmetrical ionic conditions, and the permeability ratios were calculated from the fit with the Goldman-Hodgkin-Katz equation. Our work shows that lysenin channels are ion-selective and the determined permeability coefficients are cation and anion-species dependent. We also exploited the unique property of lysenin channels to transition to a stable sub-conducting state upon exposure to calcium ions and assessed their subsequent change in ionic selectivity. The observed loss of selectivity was implemented in an electrical model describing the dependency of reversal potentials on calcium concentration. In conclusion, our work demonstrates that this pore-forming toxin presents ionic selectivity but this is adjusted by the particular conduction state of the channels.
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Affiliation(s)
- Andrew Bogard
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Pangaea W. Finn
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
| | - Fulton McKinney
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
| | - Ilinca M. Flacau
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
| | - Aviana R. Smith
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
| | - Rosey Whiting
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Daniel Fologea
- Department of Physics, Boise State University, Boise, ID 83725, USA; (A.B.); (P.W.F.); (F.M.); (I.M.F.); (A.R.S.); (R.W.)
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
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33
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Islam MS, Gaston JP, Baker MAB. Fluorescence Approaches for Characterizing Ion Channels in Synthetic Bilayers. MEMBRANES 2021; 11:857. [PMID: 34832086 PMCID: PMC8619978 DOI: 10.3390/membranes11110857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/25/2021] [Accepted: 10/28/2021] [Indexed: 12/12/2022]
Abstract
Ion channels are membrane proteins that play important roles in a wide range of fundamental cellular processes. Studying membrane proteins at a molecular level becomes challenging in complex cellular environments. Instead, many studies focus on the isolation and reconstitution of the membrane proteins into model lipid membranes. Such simpler, in vitro, systems offer the advantage of control over the membrane and protein composition and the lipid environment. Rhodopsin and rhodopsin-like ion channels are widely studied due to their light-interacting properties and are a natural candidate for investigation with fluorescence methods. Here we review techniques for synthesizing liposomes and for reconstituting membrane proteins into lipid bilayers. We then summarize fluorescence assays which can be used to verify the functionality of reconstituted membrane proteins in synthetic liposomes.
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Affiliation(s)
- Md. Sirajul Islam
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia; (M.S.I.); (J.P.G.)
| | - James P. Gaston
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia; (M.S.I.); (J.P.G.)
| | - Matthew A. B. Baker
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington, NSW 2052, Australia; (M.S.I.); (J.P.G.)
- CSIRO Synthetic Biology Future Science Platform, GPO Box 2583, Brisbane, QLD 4001, Australia
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Mukherjee A, Ghule S, Vanka K. Computational Insights into the Role of External and Local Electric Fields in Macrocyclic Chemical and Biological Systems. Chemphyschem 2021; 22:2484-2492. [PMID: 34606681 DOI: 10.1002/cphc.202100581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/02/2021] [Indexed: 11/06/2022]
Abstract
The investigation of the role of the electric field in systems of widespread interest employing computational techniques is an emerging area of research. The outcome of applying an oriented external electric field (OEEF) on the geometric and electronic properties of the chemically unique π-conjugated cyclic carbon ring compounds has been explored with density functional theory (DFT). Distinct changes in the structural and electronic features of such ring compounds are observed upon the application of OEEFs. Importantly, the calculations indicate that a mixed aliphatic-aromatic conjugated ring converts from a singlet to a triplet after the application of an OEEF, suggesting potential applications in optoelectronics for such molecules, without the need for photochemically induced change in the spin state. Furthermore, the influence of built-in local electric fields (LEFs) present in naturally occurring macrocyclic systems such as valinomycin has also been explored. Static and ab initio molecular dynamics (AIMD) calculations indicate that LEFs are the primary driving factor in determining the energetically favoured position of counter anions such as chloride (Cl- ) in the potassium (K+ ) and sodium (Na+ ) coordinated valinomycin macrocycle structures: they exist inside the cage in the case of K+ sequestration by valinomycin and outside for Na+ . This divergence has been proposed to be the determining factor for the selectivity of the valinomycin macrocycle for binding a K+ cation over Na+ .
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Affiliation(s)
- Anagh Mukherjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Siddharth Ghule
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Kumar Vanka
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
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35
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Şterbuleac D. Molecular dynamics: a powerful tool for studying the medicinal chemistry of ion channel modulators. RSC Med Chem 2021; 12:1503-1518. [PMID: 34671734 PMCID: PMC8459385 DOI: 10.1039/d1md00140j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 07/21/2021] [Indexed: 01/10/2023] Open
Abstract
Molecular dynamics (MD) simulations allow researchers to investigate the behavior of desired biological targets at ever-decreasing costs with ever-increasing precision. Among the biological macromolecules, ion channels are remarkable transmembrane proteins, capable of performing special biological processes and revealing a complex regulatory matrix, including modulation by small molecules, either endogenous or exogenous. Recently, given the developments in ion channel structure determination and accessibility of bio-computational techniques, MD and related tools are becoming increasingly popular in the intense research area regarding ligand-channel interactions. This review synthesizes and presents the most important fields of MD involvement in investigating channel-molecule interactions, including, but not limited to, deciphering the binding modes of ligands to their ion channel targets and the mechanisms through which chemical compounds exert their effect on channel function. Special attention is devoted to the importance of more elaborate methods, such as free energy calculations, while principles regarding drug design and discovery are highlighted. Several technical aspects involving the creation and simulation of channel-molecule MD systems (ligand parameterization, proper membrane setup, system building, etc.) are also presented.
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Affiliation(s)
- Daniel Şterbuleac
- Department of Health and Human Development, "Ştefan cel Mare" University of Suceava Str. Universităţii 13, 720229, E Building Suceava Romania
- Department of Forestry and Environmental Protection, "Ştefan cel Mare" University of Suceava Str. Universităţii 13, 720229, E Building Suceava Romania
- Integrated Center for Research, Development and Innovation in Advanced Materials, Nanotechnologies and Distributed Systems for Fabrication and Control (MANSiD), "Ştefan cel Mare" University of Suceava Str. Universităţii 13 720229 Suceava Romania
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36
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Conductance selectivity of Na + across the K + channel via Na + trapped in a tortuous trajectory. Proc Natl Acad Sci U S A 2021; 118:2017168118. [PMID: 33741736 DOI: 10.1073/pnas.2017168118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Ion selectivity of the potassium channel is crucial for regulating electrical activity in living cells; however, the mechanism underlying the potassium channel selectivity that favors large K+ over small Na+ remains unclear. Generally, Na+ is not completely excluded from permeation through potassium channels. Herein, the distinct nature of Na+ conduction through the prototypical KcsA potassium channel was examined. Single-channel current recordings revealed that, at a high Na+ concentration (200 mM), the channel was blocked by Na+, and this blocking was relieved at high membrane potentials, suggesting the passage of Na+ across the channel. At a 2,000 mM Na+ concentration, single-channel Na+ conductance was measured as one-eightieth of the K+ conductance, indicating that the selectivity filter allows substantial conduit of Na+ Molecular dynamics simulations revealed unprecedented atomic trajectories of Na+ permeation. In the selectivity filter having a series of carbonyl oxygen rings, a smaller Na+ was distributed off-center in eight carbonyl oxygen-coordinated sites as well as on-center in four carbonyl oxygen-coordinated sites. This amphipathic nature of Na+ coordination yielded a continuous but tortuous path along the filter. Trapping of Na+ in many deep free energy wells in the filter caused slow elution. Conversely, K+ is conducted via a straight path, and as the number of occupied K+ ions increased to three, the concerted conduction was accelerated dramatically, generating the conductance selectivity ratio of up to 80. The selectivity filter allows accommodation of different ion species, but the ion coordination and interactions between ions render contrast conduction rates, constituting the potassium channel conductance selectivity.
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38
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Domene C, Ocello R, Masetti M, Furini S. Ion Conduction Mechanism as a Fingerprint of Potassium Channels. J Am Chem Soc 2021; 143:12181-12193. [PMID: 34323472 DOI: 10.1021/jacs.1c04802] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
K+-channels are membrane proteins that regulate the selective conduction of potassium ions across cell membranes. Although the atomic mechanisms of K+ permeation have been extensively investigated, previous work focused on characterizing the selectivity and occupancy of the binding sites, the role of water molecules in the conduction process, or the identification of the minimum energy pathways enabling permeation. Here, we exploit molecular dynamics simulations and the analytical power of Markov state models to perform a comparative study of ion conduction in three distinct channel models. Significant differences emerged in terms of permeation mechanisms and binding site occupancy by potassium ions and/or water molecules from 100 μs cumulative trajectories. We found that, at odds with the current paradigm, each system displays a characteristic permeation mechanism, and thus, there is not a unique way by which potassium ions move through K+-channels. The high functional diversity of K+-channels can be attributed in part to the differences in conduction features that have emerged from this work. This study provides crucial information and further inspiration for wet-lab chemists designing new synthetic strategies to produce versatile artificial ion channels that emulate membrane transport for their applications in diagnosis, sensors, the next generation of water treatment technologies, etc., as the ability of synthetic channels to transport molecular ions across a bilayer in a controlled way is usually governed through the choice of metal ions, their oxidation states, or their coordination geometries.
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Affiliation(s)
- Carmen Domene
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, U.K.,Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, U.K
| | - Riccardo Ocello
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy
| | - Matteo Masetti
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum-Università di Bologna, Via Belmeloro 6, 40126 Bologna, Italy
| | - Simone Furini
- Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
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39
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Brown RB. Sodium Toxicity in the Nutritional Epidemiology and Nutritional Immunology of COVID-19. MEDICINA (KAUNAS, LITHUANIA) 2021; 57:739. [PMID: 34440945 PMCID: PMC8399536 DOI: 10.3390/medicina57080739] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/17/2021] [Accepted: 07/19/2021] [Indexed: 02/06/2023]
Abstract
Dietary factors in the etiology of COVID-19 are understudied. High dietary sodium intake leading to sodium toxicity is associated with comorbid conditions of COVID-19 such as hypertension, kidney disease, stroke, pneumonia, obesity, diabetes, hepatic disease, cardiac arrhythmias, thrombosis, migraine, tinnitus, Bell's palsy, multiple sclerosis, systemic sclerosis, and polycystic ovary syndrome. This article synthesizes evidence from epidemiology, pathophysiology, immunology, and virology literature linking sodium toxicological mechanisms to COVID-19 and SARS-CoV-2 infection. Sodium toxicity is a modifiable disease determinant that impairs the mucociliary clearance of virion aggregates in nasal sinuses of the mucosal immune system, which may lead to SARS-CoV-2 infection and viral sepsis. In addition, sodium toxicity causes pulmonary edema associated with severe acute respiratory syndrome, as well as inflammatory immune responses and other symptoms of COVID-19 such as fever and nasal sinus congestion. Consequently, sodium toxicity potentially mediates the association of COVID-19 pathophysiology with SARS-CoV-2 infection. Sodium dietary intake also increases in the winter, when sodium losses through sweating are reduced, correlating with influenza-like illness outbreaks. Increased SARS-CoV-2 infections in lower socioeconomic classes and among people in government institutions are linked to the consumption of foods highly processed with sodium. Interventions to reduce COVID-19 morbidity and mortality through reduced-sodium diets should be explored further.
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Affiliation(s)
- Ronald B Brown
- School of Public Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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40
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Hendriks K, Öster C, Shi C, Sun H, Lange A. Sodium Ions Do Not Stabilize the Selectivity Filter of a Potassium Channel. J Mol Biol 2021; 433:167091. [PMID: 34090923 DOI: 10.1016/j.jmb.2021.167091] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/12/2021] [Accepted: 05/27/2021] [Indexed: 11/28/2022]
Abstract
Ion conduction is an essential function for electrical activity in all organisms. The non-selective ion channel NaK was previously shown to adopt two stable conformations of the selectivity filter. Here, we present solid-state NMR measurements of NaK demonstrating a population shift between these conformations induced by changing the ions in the sample while the overall structure of NaK is not affected. We show that two K+-selective mutants (NaK2K and NaK2K-Y66F) suffer a complete loss of selectivity filter stability under Na+ conditions, but do not collapse into a defined structure. Widespread chemical shift perturbations are seen between the Na+ and K+ states of the K+-selective mutants in the region of the pore helix indicating structural changes. We conclude that the stronger link between the selectivity filter and the pore helix in the K+-selective mutants, compared to the non-selective wild-type NaK channel, reduces the ion-dependent conformational flexibility of the selectivity filter.
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Affiliation(s)
- Kitty Hendriks
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Carl Öster
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Chaowei Shi
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany; Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Huangshan Road 443, Hefei 230027, China
| | - Han Sun
- Structural Chemistry and Computational Biophysics Group, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Adam Lange
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125 Berlin, Germany; Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115 Berlin, Germany.
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41
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Gibby WAT, Barabash ML, Guardiani C, Luchinsky DG, McClintock PVE. Physics of Selective Conduction and Point Mutation in Biological Ion Channels. PHYSICAL REVIEW LETTERS 2021; 126:218102. [PMID: 34114848 DOI: 10.1103/physrevlett.126.218102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
We introduce a statistical and linear response theory of selective conduction in biological ion channels with multiple binding sites and possible point mutation. We derive an effective grand-canonical ensemble and generalized Einstein relations for the selectivity filter, assuming strongly coordinated ionic motion, and allowing for ionic Coulomb blockade. The theory agrees well with data from the KcsA K^{+} channel and a mutant. We show that the Eisenman relations for thermodynamic selectivity follow from the condition for fast conduction and find that maximum conduction requires the binding sites to be nearly identical.
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Affiliation(s)
- W A T Gibby
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - M L Barabash
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - C Guardiani
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
- Department of Mechanical and Aerospace Engineering, Sapienza University, Rome 00184, Italy
| | - D G Luchinsky
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
- KBR Inc., Ames Research Center, Moffett Field, Mountain View, California 94035, USA
| | - P V E McClintock
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
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42
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Pizzagalli MD, Bensimon A, Superti‐Furga G. A guide to plasma membrane solute carrier proteins. FEBS J 2021; 288:2784-2835. [PMID: 32810346 PMCID: PMC8246967 DOI: 10.1111/febs.15531] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/07/2020] [Accepted: 08/17/2020] [Indexed: 12/13/2022]
Abstract
This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.
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Affiliation(s)
- Mattia D. Pizzagalli
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Ariel Bensimon
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Giulio Superti‐Furga
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Center for Physiology and PharmacologyMedical University of ViennaAustria
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43
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Roy RN, Hendriks K, Kopec W, Abdolvand S, Weiss KL, de Groot BL, Lange A, Sun H, Coates L. Structural plasticity of the selectivity filter in a nonselective ion channel. IUCRJ 2021; 8:421-430. [PMID: 33953928 PMCID: PMC8086165 DOI: 10.1107/s205225252100213x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
The sodium potassium ion channel (NaK) is a nonselective ion channel that conducts both sodium and potassium across the cellular membrane. A new crystallographic structure of NaK reveals conformational differences in the residues that make up the selectivity filter between the four subunits that form the ion channel and the inner helix of the ion channel. The crystallographic structure also identifies a side-entry, ion-conduction pathway for Na+ permeation that is unique to NaK. NMR studies and molecular dynamics simulations confirmed the dynamical nature of the top part of the selectivity filter and the inner helix in NaK as also observed in the crystal structure. Taken together, these results indicate that the structural plasticity of the selectivity filter combined with the dynamics of the inner helix of NaK are vital for the efficient conduction of different ions through the non-selective ion channel of NaK.
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Affiliation(s)
- Raktim N. Roy
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Kitty Hendriks
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Wojciech Kopec
- Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Saeid Abdolvand
- Structural Chemistry and Computational Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Kevin L. Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
| | - Bert L. de Groot
- Computational Biomolecular Dynamics Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Adam Lange
- Department of Molecular Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Han Sun
- Structural Chemistry and Computational Biophysics, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany
| | - Leighton Coates
- Second Target Station, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831, USA
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44
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Carnevale V, Delemotte L, Howard RJ. Molecular Dynamics Simulations of Ion Channels. Trends Biochem Sci 2021; 46:621-622. [PMID: 33941431 DOI: 10.1016/j.tibs.2021.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/06/2021] [Accepted: 04/06/2021] [Indexed: 10/21/2022]
Affiliation(s)
- Vincenzo Carnevale
- Institute for Computational Molecular Science, Temple University, Philadelphia, PA 19122, USA
| | - Lucie Delemotte
- Department of Applied Physics, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden.
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics and Science for Life Laboratory, Stockholm University, 17165 Solna, Sweden
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45
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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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46
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Alberini G, Benfenati F, Maragliano L. Structural Mechanism of ω-Currents in a Mutated Kv7.2 Voltage Sensor Domain from Molecular Dynamics Simulations. J Chem Inf Model 2021; 61:1354-1367. [PMID: 33570938 PMCID: PMC8023575 DOI: 10.1021/acs.jcim.0c01407] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
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Activation of voltage-gated
ion channels is regulated by conformational
changes of the voltage sensor domains (VSDs), four water- and ion-impermeable
modules peripheral to the central, permeable pore domain. Anomalous
currents, defined as ω-currents, have been recorded in response
to mutations of residues on the VSD S4 helix and associated with ion
fluxes through the VSDs. In humans, gene defects in the potassium
channel Kv7.2 result in a broad range of epileptic disorders, from
benign neonatal seizures to severe epileptic encephalopathies. Experimental
evidence suggests that the R207Q mutation in S4, associated with peripheral
nerve hyperexcitability, induces ω-currents at depolarized potentials,
but the fine structural details are still elusive. In this work, we
use atom-detailed molecular dynamics simulations and a refined model
structure of the Kv7.2 VSD in the active conformation in a membrane/water
environment to study the effect of R207Q and four additional mutations
of proven clinical importance. Our results demonstrate that the R207Q
mutant shows the most pronounced increase of hydration in the internal
VSD cavity, a feature favoring the occurrence of ω-currents.
Free energy and kinetics calculations of sodium permeation through
the native and mutated VSD indicate as more favorable the formation
of a cationic current in the latter. Overall, our simulations establish
a mechanistic linkage between genetic variations and their physiological
outcome, by providing a computational description that includes both
thermodynamic and kinetic features of ion permeation associated with
ω-currents.
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Affiliation(s)
- Giulio Alberini
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi, 10, 16132 Genova, Italy.,Department of Experimental Medicine, Università degli Studi di Genova, Viale Benedetto XV, 3, 16132 Genova, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi, 10, 16132 Genova, Italy.,IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi, 10, 16132 Genova, Italy
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology (NSYN@UniGe), Istituto Italiano di Tecnologia, Largo Rosanna Benzi, 10, 16132 Genova, Italy.,Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
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47
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Linsdell P. On the relationship between anion binding and chloride conductance in the CFTR anion channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183558. [PMID: 33444622 DOI: 10.1016/j.bbamem.2021.183558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 12/26/2022]
Abstract
Mutations at many sites within the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel pore region result in changes in chloride conductance. Although chloride binding in the pore - as well as interactions between concurrently bound chloride ions - are thought to be important facets of the chloride permeation mechanism, little is known about the relationship between anion binding and chloride conductance. The present work presents a comprehensive investigation of a number of anion binding properties in different pore mutants with differential effects on chloride conductance. When multiple pore mutants are compared, conductance appears best correlated with the ability of anions to bind to the pore when it is already occupied by chloride ions. In contrast, conductance was not correlated with biophysical measures of anion:anion interactions inside the pore. Although these findings suggest anion binding is required for high conductance, mutations that strengthened anion binding had very little effect on conductance, especially at high chloride concentrations, suggesting that the wild-type CFTR pore is already close to saturated with chloride ions. These results are used to support a revised model of chloride permeation in CFTR in which the overall chloride occupancy of multiple loosely-defined chloride binding sites results in high chloride conductance through the pore.
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Affiliation(s)
- Paul Linsdell
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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48
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Novel insights in linking solvent relaxation dynamics and protein conformations utilizing red edge excitation shift approach. Emerg Top Life Sci 2021; 5:89-101. [PMID: 33416893 DOI: 10.1042/etls20200256] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/14/2020] [Accepted: 12/18/2020] [Indexed: 01/01/2023]
Abstract
Protein hydration dynamics plays an important role in many physiological processes since protein fluctuations, slow solvation, and the dynamics of hydrating water are all intrinsically related. Red edge excitation shift (REES) is a unique and powerful wavelength-selective (i.e. excitation-energy dependent) fluorescence approach that can be used to directly monitor the environment-induced restriction and dynamics around a polar fluorophore in a complex biological system. This review is mainly focused on recent applications of REES and a novel analysis of REES data to monitor the structural dynamics, functionally relevant conformational transitions and to unmask the structural ensembles in proteins. In addition, the novel utility of REES in imaging protein aggregates in a cellular context is discussed. We believe that the enormous potential of REES approach showcased in this review will engage more researchers, particularly from life sciences.
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49
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Miao Y, Lam D, Zhuang J, Zhu J, Poget SF, Tang M. Membrane Topology of an Ion Channel Detected by Solid-State Nuclear Magnetic Resonance and Paramagnetic Effects. J Phys Chem Lett 2020; 11:9795-9801. [PMID: 33151058 DOI: 10.1021/acs.jpclett.0c02014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ion channels are often targeted by toxins or other ligands to modify their channel activities and alter ion conductance. Interactions between toxins and ion channels could result in changes in membrane insertion depth for residues close to the binding site. Paramagnetic solid-state nuclear magnetic resonance (SSNMR) has shown great potential in providing structural information on membrane samples. We used KcsA as a model ion channel to investigate how the paramagnetic effects of Mn2+ and Dy3+ ions with headgroup-modified chelator lipids would influence the SSNMR signals of membrane proteins in proteoliposomes. Spectral comparisons have shown significant changes of peak intensities for the residues in the loop or terminal regions due to paramagnetic effects corresponding to the close proximity to the membrane surface. Hence, these results demonstrate that paramagnetic SSNMR can be used to detect surface residues based on the topology and membrane insertion properties for integral membrane proteins.
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Affiliation(s)
- Yimin Miao
- Department of Chemistry, College of Staten Island-Ph.D. Programs in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Dennis Lam
- Department of Chemistry, College of Staten Island-Ph.D. Programs in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Jianqin Zhuang
- Department of Chemistry, College of Staten Island-Ph.D. Programs in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Jing Zhu
- Department of Chemistry, College of Staten Island-Ph.D. Programs in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Sebastien F Poget
- Department of Chemistry, College of Staten Island-Ph.D. Programs in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Ming Tang
- Department of Chemistry, College of Staten Island-Ph.D. Programs in Chemistry and Biochemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
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50
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Korolev N. How potassium came to be the dominant biological cation: of metabolism, chemiosmosis, and cation selectivity since the beginnings of life. Bioessays 2020; 43:e2000108. [PMID: 33191554 DOI: 10.1002/bies.202000108] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/30/2020] [Accepted: 09/30/2020] [Indexed: 12/22/2022]
Abstract
In the cytoplasm of practically all living cells, potassium is the major cation while sodium dominates in the media (seawater, extracellular fluids). Both prokaryotes and eukaryotes have elaborate mechanisms and spend significant energy to maintain this asymmetric K+ /Na+ distribution. This essay proposes an original line of evidence to explain how bacteria selected potassium at the very beginning of the evolutionary process and why it remains essential for eukaryotes.
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Affiliation(s)
- Nikolay Korolev
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, Singapore
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