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Turcio R, Di Matteo F, Capolupo I, Ciaglia T, Musella S, Di Chio C, Stagno C, Campiglia P, Bertamino A, Ostacolo C. Voltage-Gated K + Channel Modulation by Marine Toxins: Pharmacological Innovations and Therapeutic Opportunities. Mar Drugs 2024; 22:350. [PMID: 39195466 DOI: 10.3390/md22080350] [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: 06/10/2024] [Revised: 07/25/2024] [Accepted: 07/28/2024] [Indexed: 08/29/2024] Open
Abstract
Bioactive compounds are abundant in animals originating from marine ecosystems. Ion channels, which include sodium, potassium, calcium, and chloride, together with their numerous variants and subtypes, are the primary molecular targets of the latter. Based on their cellular targets, these venom compounds show a range of potencies and selectivity and may have some therapeutic properties. Due to their potential as medications to treat a range of (human) diseases, including pain, autoimmune disorders, and neurological diseases, marine molecules have been the focus of several studies over the last ten years. The aim of this review is on the various facets of marine (or marine-derived) molecules, ranging from structural characterization and discovery to pharmacology, culminating in the development of some "novel" candidate chemotherapeutic drugs that target potassium channels.
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Affiliation(s)
- Rita Turcio
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | | | - Ilaria Capolupo
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | - Tania Ciaglia
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | - Simona Musella
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | - Carla Di Chio
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, 98166 Messina, Italy
| | - Claudio Stagno
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, 98166 Messina, Italy
| | - Pietro Campiglia
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | - Alessia Bertamino
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
| | - Carmine Ostacolo
- Department of Pharmacy, University of Salerno, 84084 Fisciano, Italy
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2
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Chandy KG, Sanches K, Norton RS. Structure of the voltage-gated potassium channel K V1.3: Insights into the inactivated conformation and binding to therapeutic leads. Channels (Austin) 2023; 17:2253104. [PMID: 37695839 PMCID: PMC10496531 DOI: 10.1080/19336950.2023.2253104] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/13/2023] Open
Abstract
The voltage-gated potassium channel KV1.3 is an important therapeutic target for the treatment of autoimmune and neuroinflammatory diseases. The recent structures of KV1.3, Shaker-IR (wild-type and inactivating W434F mutant) and an inactivating mutant of rat KV1.2-KV2.1 paddle chimera (KVChim-W362F+S367T+V377T) reveal that the transition of voltage-gated potassium channels from the open-conducting conformation into the non-conducting inactivated conformation involves the rupture of a key intra-subunit hydrogen bond that tethers the selectivity filter to the pore helix. Breakage of this bond allows the side chains of residues at the external end of the selectivity filter (Tyr447 and Asp449 in KV1.3) to rotate outwards, dilating the outer pore and disrupting ion permeation. Binding of the peptide dalazatide (ShK-186) and an antibody-ShK fusion to the external vestibule of KV1.3 narrows and stabilizes the selectivity filter in the open-conducting conformation, although K+ efflux is blocked by the peptide occluding the pore through the interaction of ShK-Lys22 with the backbone carbonyl of KV1.3-Tyr447 in the selectivity filter. Electrophysiological studies on ShK and the closely-related peptide HmK show that ShK blocks KV1.3 with significantly higher potency, even though molecular dynamics simulations show that ShK is more flexible than HmK. Binding of the anti-KV1.3 nanobody A0194009G09 to the turret and residues in the external loops of the voltage-sensing domain enhances the dilation of the outer selectivity filter in an exaggerated inactivated conformation. These studies lay the foundation to further define the mechanism of slow inactivation in KV channels and can help guide the development of future KV1.3-targeted immuno-therapeutics.
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Affiliation(s)
- K. George Chandy
- LKCMedicine-ICESing Ion Channel Platform, Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
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3
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Montero-Domínguez PA, Mares-Sámano S, Garduño-Juárez R. Insight on the interaction between the scorpion toxin blocker Discrepin on potassium voltage-gated channel Kv4.3 by molecular dynamics simulations. J Biomol Struct Dyn 2022:1-10. [PMID: 35916276 DOI: 10.1080/07391102.2022.2106514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Discrepin is a 38-residue α-toxin extracted from the venom of the Venezuelan scorpion Tityus discrepans, which inhibits ionic transit in the voltage-dependent potassium channels (Kv) of A-type current. The effect of specific residues on the IC50 between Discrepine and Kv4.3, the main component of A-type currents, is known; however, the molecular details of the toxin-channel interaction are not known. In this work, we present interaction models between Discrepin (wt) and two peptide variants (V6K/D20K and K13A) on the pore-forming domain of the Kv4.3 channel obtained from homology, docking, and molecular dynamics modeling techniques. The free energy calculations in these models correspond to the order of the experimentally determined IC50 values. Our studies shed light on the role of the K13 residue as responsible for occluding the Kv4.3 selectivity filter and the importance of the V6K mutation in the approach and stabilization of toxin-channel complex interactions.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
| | - Sergio Mares-Sámano
- CONACYT - Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Ramón Garduño-Juárez
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, México
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4
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Sanches K, Wai DCC, Norton RS. Conformational dynamics in peptide toxins: Implications for receptor interactions and molecular design. Toxicon 2021; 201:127-140. [PMID: 34454969 DOI: 10.1016/j.toxicon.2021.08.020] [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: 07/07/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 10/20/2022]
Abstract
Peptide toxins are potent and often exquisitely selective probes of the structure and function of ion channels and receptors, and are therefore of significant interest to the pharmaceutical and biotech industries as both pharmacological tools and therapeutic leads. The three-dimensional structures of peptide toxins are essential as a basis for understanding their structure-activity relationships and their binding to target receptors, as well as in guiding the design of analogues with modified potency and/or selectivity for key targets. NMR spectroscopy has played a key role in elucidating the structures of peptide toxins and probing their structure-function relationships. In this article, we highlight the additional important contribution of NMR to characterising the dynamics of peptide toxins. We also compare the information available from NMR measurements with that afforded by molecular dynamics simulations. We describe several examples of the importance of dynamics measurements over a range of timescales for understanding the structure-function relationships of peptide toxins and their receptor engagement. Peptide toxins that inhibit the voltage-gated potassium channel KV1.3 with pM affinities display different degrees of conformational flexibility, even though they contain multiple disulfide bonds, and this flexibility can affect the relative orientation of residues that have been shown to be critical for channel binding. Information on the dynamic properties of peptide toxins is important in the design of analogues or mimetics where receptor-bound structures are not available.
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Affiliation(s)
- Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia; ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia
| | - Dorothy C C Wai
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia; ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia.
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5
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Gubič Š, Hendrickx LA, Toplak Ž, Sterle M, Peigneur S, Tomašič T, Pardo LA, Tytgat J, Zega A, Mašič LP. Discovery of K V 1.3 ion channel inhibitors: Medicinal chemistry approaches and challenges. Med Res Rev 2021; 41:2423-2473. [PMID: 33932253 PMCID: PMC8252768 DOI: 10.1002/med.21800] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 03/03/2021] [Accepted: 03/19/2021] [Indexed: 12/12/2022]
Abstract
The KV 1.3 voltage-gated potassium ion channel is involved in many physiological processes both at the plasma membrane and in the mitochondria, chiefly in the immune and nervous systems. Therapeutic targeting KV 1.3 with specific peptides and small molecule inhibitors shows great potential for treating cancers and autoimmune diseases, such as multiple sclerosis, type I diabetes mellitus, psoriasis, contact dermatitis, rheumatoid arthritis, and myasthenia gravis. However, no KV 1.3-targeted compounds have been approved for therapeutic use to date. This review focuses on the presentation of approaches for discovering new KV 1.3 peptide and small-molecule inhibitors, and strategies to improve the selectivity of active compounds toward KV 1.3. Selectivity of dalatazide (ShK-186), a synthetic derivate of the sea anemone toxin ShK, was achieved by chemical modification and has successfully reached clinical trials as a potential therapeutic for treating autoimmune diseases. Other peptides and small-molecule inhibitors are critically evaluated for their lead-like characteristics and potential for progression into clinical development. Some small-molecule inhibitors with well-defined structure-activity relationships have been optimized for selective delivery to mitochondria, and these offer therapeutic potential for the treatment of cancers. This overview of KV 1.3 inhibitors and methodologies is designed to provide a good starting point for drug discovery to identify novel effective KV 1.3 modulators against this target in the future.
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Affiliation(s)
- Špela Gubič
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | - Louise A. Hendrickx
- Toxicology and PharmacologyUniversity of Leuven, Campus GasthuisbergLeuvenBelgium
| | - Žan Toplak
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | - Maša Sterle
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | - Steve Peigneur
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
| | | | - Luis A. Pardo
- AG OncophysiologyMax‐Planck Institute for Experimental MedicineGöttingenGermany
| | - Jan Tytgat
- Toxicology and PharmacologyUniversity of Leuven, Campus GasthuisbergLeuvenBelgium
| | - Anamarija Zega
- Faculty of PharmacyUniversity of LjubljanaLjubljanaSlovenia
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6
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Patel D, Kuyucak S, Doupnik CA. Structural Determinants Mediating Tertiapin Block of Neuronal Kir3.2 Channels. Biochemistry 2020; 59:836-850. [PMID: 31990535 DOI: 10.1021/acs.biochem.9b01098] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Tertiapin (TPN) is a 21 amino acid venom peptide from Apis mellifera that inhibits certain members of the inward rectifier potassium (Kir) channel family at a nanomolar affinity with limited specificity. Structure-based computational simulations predict that TPN behaves as a pore blocker; however, the molecular determinants mediating block of neuronal Kir3 channels have been inconclusive and unvalidated. Here, using molecular docking and molecular dynamics (MD) simulations with 'potential of mean force' (PMF) calculations, we investigated the energetically most favored interaction of TPN with several Kir3.x channel structures. The resulting binding model for Kir3.2-TPN complexes was then tested by targeted mutagenesis of the predicted contact sites, and their impact on the functional channel block was measured electrophysiologically. Together, our findings indicate that a high-affinity TPN block of Kir3.2 channels involves a pore-inserting lysine side chain requiring (1) hydrophobic interactions at a phenylalanine ring surrounding the channel pore and (2) electrostatic interactions with two adjacent Kir3.2 turret regions. Together, these interactions collectively stabilize high-affinity toxin binding to the Kir3.2 outer vestibule, which orients the ε-amino group of TPN-K21 to occupy the outermost K+ binding site of the selectivity filter. The structural determinants for the TPN block described here also revealed a favored subunit arrangement for assembled Kir3.x heteromeric channels, in addition to a multimodal binding capacity of TPN variants consistent with the functional dyad model for polybasic peptide pore blockers. These novel findings will aid efforts in re-engineering the TPN pharmacophore to develop peptide variants having unique and distinct Kir channel blocking properties.
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Affiliation(s)
- Dharmeshkumar Patel
- School of Physics , University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Serdar Kuyucak
- School of Physics , University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Craig A Doupnik
- Department of Molecular Pharmacology & Physiology , University of South Florida College of Medicine , 12901 Bruce B. Downs Boulevard , Tampa , Florida 33612 , United States
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7
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Iwakawa N, Baxter NJ, Wai DCC, Fowler NJ, Morales RAV, Sugase K, Norton RS, Williamson MP. Conformational exchange in the potassium channel blocker ShK. Sci Rep 2019; 9:19307. [PMID: 31848433 PMCID: PMC6917819 DOI: 10.1038/s41598-019-55806-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 11/21/2019] [Indexed: 11/25/2022] Open
Abstract
ShK is a 35-residue disulfide-linked polypeptide produced by the sea anemone Stichodactyla helianthus, which blocks the potassium channels Kv1.1 and Kv1.3 with pM affinity. An analogue of ShK has been developed that blocks Kv1.3 > 100 times more potently than Kv1.1, and has completed Phase 1b clinical trials for the treatment of autoimmune diseases such as psoriasis and rheumatoid arthritis. Previous studies have indicated that ShK undergoes a conformational exchange that is critical to its function, but this has proved difficult to characterise. Here, we have used high hydrostatic pressure as a tool to increase the population of the alternative state, which is likely to resemble the active form that binds to the Kv1.3 channel. By following changes in chemical shift with pressure, we have derived the chemical shift values of the low- and high-pressure states, and thus characterised the locations of structural changes. The main difference is in the conformation of the Cys17-Cys32 disulfide, which is likely to affect the positions of the critical Lys22-Tyr23 pair by twisting the 21–24 helix and increasing the solvent exposure of the Lys22 sidechain, as indicated by molecular dynamics simulations.
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Affiliation(s)
- Naoto Iwakawa
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-Ku, Kyoto, 615-8510, Japan.,Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Nicola J Baxter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Dorothy C C Wai
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Nicholas J Fowler
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Rodrigo A V Morales
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia.,CSL Limited (Bio21), 30 Flemington Road, Parkville, Victoria, 3010, Australia
| | - Kenji Sugase
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-Ku, Kyoto, 615-8510, Japan
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia. .,ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, 3052, Australia.
| | - Mike P Williamson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.
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8
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Su Z, Burchfield JG, Yang P, Humphrey SJ, Yang G, Francis D, Yasmin S, Shin SY, Norris DM, Kearney AL, Astore MA, Scavuzzo J, Fisher-Wellman KH, Wang QP, Parker BL, Neely GG, Vafaee F, Chiu J, Yeo R, Hogg PJ, Fazakerley DJ, Nguyen LK, Kuyucak S, James DE. Global redox proteome and phosphoproteome analysis reveals redox switch in Akt. Nat Commun 2019; 10:5486. [PMID: 31792197 PMCID: PMC6889415 DOI: 10.1038/s41467-019-13114-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 10/18/2019] [Indexed: 01/04/2023] Open
Abstract
Protein oxidation sits at the intersection of multiple signalling pathways, yet the magnitude and extent of crosstalk between oxidation and other post-translational modifications remains unclear. Here, we delineate global changes in adipocyte signalling networks following acute oxidative stress and reveal considerable crosstalk between cysteine oxidation and phosphorylation-based signalling. Oxidation of key regulatory kinases, including Akt, mTOR and AMPK influences the fidelity rather than their absolute activation state, highlighting an unappreciated interplay between these modifications. Mechanistic analysis of the redox regulation of Akt identified two cysteine residues in the pleckstrin homology domain (C60 and C77) to be reversibly oxidized. Oxidation at these sites affected Akt recruitment to the plasma membrane by stabilizing the PIP3 binding pocket. Our data provide insights into the interplay between oxidative stress-derived redox signalling and protein phosphorylation networks and serve as a resource for understanding the contribution of cellular oxidation to a range of diseases.
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Affiliation(s)
- Zhiduan Su
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - James G Burchfield
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Pengyi Yang
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Mathematics and Statistics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Sean J Humphrey
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Guang Yang
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Deanne Francis
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Sabina Yasmin
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Sung-Young Shin
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC, 3800, Australia
- Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Dougall M Norris
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Alison L Kearney
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Miro A Astore
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Jonathan Scavuzzo
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Kelsey H Fisher-Wellman
- Brody School of Medicine, Physiology Department, East Carolina University, Greenville, NC, USA
- East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Qiao-Ping Wang
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life & Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Benjamin L Parker
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - G Gregory Neely
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
- The Dr. John and Anne Chong Laboratory for Functional Genomics, Charles Perkins Centre and School of Life & Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Fatemeh Vafaee
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Mathematics and Statistics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Joyce Chiu
- The Centenary Institute, Newtown, NSW, 2042, Australia
- National Health and Medical Research Council Clinical Trials Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Reichelle Yeo
- The Centenary Institute, Newtown, NSW, 2042, Australia
- National Health and Medical Research Council Clinical Trials Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Philip J Hogg
- The Centenary Institute, Newtown, NSW, 2042, Australia
- National Health and Medical Research Council Clinical Trials Centre, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Daniel J Fazakerley
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Lan K Nguyen
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, VIC, 3800, Australia
- Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Serdar Kuyucak
- School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia
| | - David E James
- Charles Perkins Centre, The University of Sydney, Sydney, NSW, 2006, Australia.
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.
- Sydney Medical School, The University of Sydney, Sydney, NSW, 2006, Australia.
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9
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Ma G, Shan X, Wang S, Tao N. Quantifying Ligand-Protein Binding Kinetics with Self-Assembled Nano-oscillators. Anal Chem 2019; 91:14149-14156. [PMID: 31593433 DOI: 10.1021/acs.analchem.9b04195] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Measuring ligand-protein interactions is critical for unveiling molecular-scale biological processes in living systems and for screening drugs. Various detection technologies have been developed, but quantifying the binding kinetics of small molecules to the proteins remains challenging because the sensitivities of the mainstream technologies decrease with the size of the ligand. Here, we report a method to measure and quantify the binding kinetics of both large and small molecules with self-assembled nano-oscillators, each consisting of a nanoparticle tethered to a surface via long polymer molecules. By applying an oscillating electric field normal to the surface, the nanoparticle oscillates, and the oscillation amplitude is proportional to the number of charges on the nano-oscillator. Upon the binding of ligands onto the nano-oscillator, the oscillation amplitude will change. Using a plasmonic imaging approach, the oscillation amplitude is measured with subnanometer precision, allowing us to accurately quantify the binding kinetics of ligands, including small molecules, to their protein receptors. This work demonstrates the capability of nano-oscillators as an useful tool for measuring the binding kinetics of both large and small molecules.
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Affiliation(s)
- Guangzhong Ma
- Biodesign Center for Bioelectronics and Biosensors , Arizona State University , Tempe , Arizona 85287 , United States.,School of Molecular Sciences , Arizona State University , Tempe , Arizona 85287 , United States
| | - Xiaonan Shan
- Biodesign Center for Bioelectronics and Biosensors , Arizona State University , Tempe , Arizona 85287 , United States.,School of Electrical, Computer and Energy Engineering , Arizona State University , Tempe , Arizona 85287 , United States
| | - Shaopeng Wang
- Biodesign Center for Bioelectronics and Biosensors , Arizona State University , Tempe , Arizona 85287 , United States
| | - Nongjian Tao
- Biodesign Center for Bioelectronics and Biosensors , Arizona State University , Tempe , Arizona 85287 , United States.,School of Electrical, Computer and Energy Engineering , Arizona State University , Tempe , Arizona 85287 , United States
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10
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Madio B, King GF, Undheim EAB. Sea Anemone Toxins: A Structural Overview. Mar Drugs 2019; 17:E325. [PMID: 31159357 PMCID: PMC6627431 DOI: 10.3390/md17060325] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/22/2019] [Accepted: 05/25/2019] [Indexed: 02/06/2023] Open
Abstract
Sea anemones produce venoms of exceptional molecular diversity, with at least 17 different molecular scaffolds reported to date. These venom components have traditionally been classified according to pharmacological activity and amino acid sequence. However, this classification system suffers from vulnerabilities due to functional convergence and functional promiscuity. Furthermore, for most known sea anemone toxins, the exact receptors they target are either unknown, or at best incomplete. In this review, we first provide an overview of the sea anemone venom system and then focus on the venom components. We have organised the venom components by distinguishing firstly between proteins and non-proteinaceous compounds, secondly between enzymes and other proteins without enzymatic activity, then according to the structural scaffold, and finally according to molecular target.
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Affiliation(s)
- Bruno Madio
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Eivind A B Undheim
- Centre for Advanced Imaging, The University of Queensland, St. Lucia, QLD 4072, Australia.
- Centre for Ecology and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
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11
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Setiadi J, Kuyucak S. A simple, parameter-free method for computing solvation free energies of ions. J Chem Phys 2019; 150:065101. [DOI: 10.1063/1.5082975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Jeffry Setiadi
- School of Physics, University of Sydney, Sydney, NSW 2006, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, NSW 2006, Australia
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12
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Rashid MH, Kuyucak S. Computational Study of the Loss-of-Function Mutations in the Kv1.5 Channel Associated with Atrial Fibrillation. ACS OMEGA 2018; 3:8882-8890. [PMID: 31459020 PMCID: PMC6645308 DOI: 10.1021/acsomega.8b01094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 07/31/2018] [Indexed: 06/10/2023]
Abstract
Atrial fibrillation (AF) is a heart disease caused by defective ion channels in the atria, which affect the action potential (AP) duration and disturb normal heart rhythm. Rapid firing of APs in neighboring atrial cells is a common mechanism of AF, and therefore, therapeutic approaches have focused on extending the AP duration by inhibiting the K+ channels involved in repolarization. Of these, Kv1.5 that carries the I Kur current is a promising target because it is expressed mainly in atria and not in ventricles. In genetic studies of AF patients, both loss-of-function and gain-of-function mutations in Kv1.5 have been identified, indicating that either decreased or increased I Kur currents could trigger AF. Blocking of already downregulated Kv1.5 channels could cause AF to become chronic. Thus, a molecular-level understanding of how the loss-of-function mutations in Kv1.5 affect I Kur would be useful for developing new therapeutics. Here, we perform molecular dynamics simulations to study the effect of three loss-of-function mutations in the pore domain of Kv1.5 on ion permeation. Comparison of the pore structures and ion free energies in the wild-type and mutant Kv1.5 channels indicates that conformational changes in the selectivity filter could hinder ion permeation in the mutant channels.
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Affiliation(s)
- Md Harunur Rashid
- Department of Chemistry,
Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- School of Engineering, RMIT University, Melbourne, Victoria 3000, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
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13
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Dutta D, Fliegel L. Molecular modeling and inhibitor docking analysis of the Na +/H + exchanger isoform one 1. Biochem Cell Biol 2018; 97:333-343. [PMID: 30058365 DOI: 10.1139/bcb-2018-0158] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Na+/H+ exchanger isoform one (NHE1) is a mammalian plasma membrane protein that removes intracellular protons, thereby elevating intracellular pH (pHi). NHE1 uses the energy of allowing an extracellular sodium down its gradient into cells to remove one intracellular proton. The ubiquitous protein has several important physiological and pathological influences on mammalian cells as a result of its activity. The three-dimensional structure of human NHE1 (hNHE1) is not known. Here, we modeled NHE1 based on the structure of MjNhaP1 of Methanocaldoccocus jannaschii in combination with biochemical surface accessibility data. hNHE1 contained 12 transmembrane segments including a characteristic Na+/H+ antiporter fold of two transmembrane segments with a helix - extended region - helix conformation crossing each other within the membrane. Amino acids 363-410 mapped principally to the extracellular surface as an extracellular loop (EL5). A large preponderance of amino acids shown to be surface accessible by biochemical experiments mapped near to, or on, the extracellular surface. Docking of Na+/H+ exchanger inhibitors to the extracellular surface suggested that inhibitor binding on an extracellular site is made up from several amino acids of different regions of the protein. The results present a novel testable, three-dimensional model illustrating NHE1 structure and accounting for experimental biochemical data.
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Affiliation(s)
- Debajyoti Dutta
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.,Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Larry Fliegel
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.,Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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14
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Krishnarjuna B, MacRaild CA, Sunanda P, Morales RAV, Peigneur S, Macrander J, Yu HH, Daly M, Raghothama S, Dhawan V, Chauhan S, Tytgat J, Pennington MW, Norton RS. Structure, folding and stability of a minimal homologue from Anemonia sulcata of the sea anemone potassium channel blocker ShK. Peptides 2018; 99:169-178. [PMID: 28993277 DOI: 10.1016/j.peptides.2017.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/03/2017] [Accepted: 10/05/2017] [Indexed: 01/01/2023]
Abstract
Peptide toxins elaborated by sea anemones target various ion-channel sub-types. Recent transcriptomic studies of sea anemones have identified several novel candidate peptides, some of which have cysteine frameworks identical to those of previously reported sequences. One such peptide is AsK132958, which was identified in a transcriptomic study of Anemonia sulcata and has a cysteine framework similar to that of ShK from Stichodactyla helianthus, but is six amino acid residues shorter. We have determined the solution structure of this novel peptide using NMR spectroscopy. The disulfide connectivities and structural scaffold of AsK132958 are very similar to those of ShK but the structure is more constrained. Toxicity assays were performed using grass shrimp (Palaemonetes sp) and Artemia nauplii, and patch-clamp electrophysiology assays were performed to assess the activity of AsK132958 against a range of voltage-gated potassium (KV) channels. AsK132958 showed no activity against grass shrimp, Artemia nauplii, or any of the KV channels tested, owing partly to the absence of a functional Lys-Tyr dyad. Three AsK132958 analogues, each containing a Tyr in the vicinity of Lys19, were therefore generated in an effort to restore binding, but none showed activity against any of KV channels tested. However, AsK132958 and its analogues are less susceptible to proteolysis than that of ShK. Our structure suggests that Lys19, which might be expected to occupy the pore of the channel, is not sufficiently accessible for binding, and therefore that AsK132958 must have a distinct functional role that does not involve KV channels.
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Affiliation(s)
- Bankala Krishnarjuna
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Punnepalli Sunanda
- NMR Research Centre, Indian Institute of Science, Bangalore 560012, India
| | - Rodrigo A V Morales
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, 3000, Leuven, Belgium
| | - Jason Macrander
- Department of Evolution, Ecology, Organismal Biology, Ohio State University, 1315 Kinnear Rd, Columbus, OH 43212, USA; Department of Biology, University of North Carolina at Charlotte, 9201 University City Blvd, Charlotte, NC 28223, USA
| | - Heidi H Yu
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, VIC 3800, Australia
| | - Marymegan Daly
- Department of Evolution, Ecology, Organismal Biology, Ohio State University, 1315 Kinnear Rd, Columbus, OH 43212, USA
| | | | - Vikas Dhawan
- Peptides International, Louisville, KY 40299, USA
| | | | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven, O&N 2, Herestraat 49, P.O. Box 922, 3000, Leuven, Belgium
| | | | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia.
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15
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Hung A, Kuyucak S, Schroeder CI, Kaas Q. Modelling the interactions between animal venom peptides and membrane proteins. Neuropharmacology 2017; 127:20-31. [PMID: 28778835 DOI: 10.1016/j.neuropharm.2017.07.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/18/2017] [Accepted: 07/31/2017] [Indexed: 12/19/2022]
Abstract
The active components of animal venoms are mostly peptide toxins, which typically target ion channels and receptors of both the central and peripheral nervous system, interfering with action potential conduction and/or synaptic transmission. The high degree of sequence conservation of their molecular targets makes a range of these toxins active at human receptors. The high selectivity and potency displayed by some of these toxins have prompted their use as pharmacological tools as well as drugs or drug leads. Molecular modelling has played an essential role in increasing our molecular-level understanding of the activity and specificity of animal toxins, as well as engineering them for biotechnological and pharmaceutical applications. This review focuses on the biological insights gained from computational and experimental studies of animal venom toxins interacting with membranes and ion channels. A host of recent X-ray crystallography and electron-microscopy structures of the toxin targets has contributed to a dramatic increase in the accuracy of the molecular models of toxin binding modes greatly advancing this exciting field of study. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Andrew Hung
- School of Science, RMIT University, GPO Box 2476, Melbourne, Victoria 3001, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Christina I Schroeder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane 4072, Australia.
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16
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Venom-derived peptide inhibitors of voltage-gated potassium channels. Neuropharmacology 2017; 127:124-138. [PMID: 28689025 DOI: 10.1016/j.neuropharm.2017.07.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/02/2017] [Accepted: 07/04/2017] [Indexed: 12/11/2022]
Abstract
Voltage-gated potassium channels play a key role in human physiology and pathology. Reflecting their importance, numerous channelopathies have been characterised that arise from mutations in these channels or from autoimmune attack on the channels. Voltage-gated potassium channels are also the target of a broad range of peptide toxins from venomous organisms, including sea anemones, scorpions, spiders, snakes and cone snails; many of these peptides bind to the channels with high potency and selectivity. In this review we describe the various classes of peptide toxins that block these channels and illustrate the broad range of three-dimensional structures that support channel blockade. The therapeutic opportunities afforded by these peptides are also highlighted. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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17
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Patel D, Kuyucak S. Computational study of aggregation mechanism in human lysozyme[D67H]. PLoS One 2017; 12:e0176886. [PMID: 28467454 PMCID: PMC5415109 DOI: 10.1371/journal.pone.0176886] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 04/19/2017] [Indexed: 11/18/2022] Open
Abstract
Aggregation of proteins is an undesired phenomena that affects both human health and bioengineered products such as therapeutic proteins. Finding preventative measures could be facilitated by a molecular-level understanding of dimer formation, which is the first step in aggregation. Here we present a molecular dynamics (MD) study of dimer formation propensity in human lysozyme and its D67H variant. Because the latter protein aggregates while the former does not, they offer an ideal system for testing the feasibility of the proposed MD approach which comprises three stages: i) partially unfolded conformers involved in dimer formation are generated via high-temperature MD simulations, ii) potential dimer structures are searched using docking and refined with MD, iii) free energy calculations are performed to find the most stable dimer structure. Our results provide a detailed explanation for how a single mutation (D67H) turns human lysozyme from non-aggregating to an aggregating protein. Conversely, the proposed method can be used to identify the residues causing aggregation in a protein, which can be mutated to prevent it.
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Affiliation(s)
- Dharmeshkumar Patel
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
- * E-mail:
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18
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Molecular Simulations of Disulfide-Rich Venom Peptides with Ion Channels and Membranes. Molecules 2017; 22:molecules22030362. [PMID: 28264446 PMCID: PMC6155311 DOI: 10.3390/molecules22030362] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 12/12/2022] Open
Abstract
Disulfide-rich peptides isolated from the venom of arthropods and marine animals are a rich source of potent and selective modulators of ion channels. This makes these peptides valuable lead molecules for the development of new drugs to treat neurological disorders. Consequently, much effort goes into understanding their mechanism of action. This paper presents an overview of how molecular simulations have been used to study the interactions of disulfide-rich venom peptides with ion channels and membranes. The review is focused on the use of docking, molecular dynamics simulations, and free energy calculations to (i) predict the structure of peptide-channel complexes; (ii) calculate binding free energies including the effect of peptide modifications; and (iii) study the membrane-binding properties of disulfide-rich venom peptides. The review concludes with a summary and outlook.
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19
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Kuyucak S, Kayser V. Biobetters From an Integrated Computational/Experimental Approach. Comput Struct Biotechnol J 2017; 15:138-145. [PMID: 28179976 PMCID: PMC5279740 DOI: 10.1016/j.csbj.2017.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/05/2017] [Accepted: 01/10/2017] [Indexed: 02/04/2023] Open
Abstract
Biobetters are new drugs designed from existing peptide or protein-based therapeutics by improving their properties such as affinity and selectivity for the target epitope, and stability against degradation. Computational methods can play a key role in such design problems—by predicting the changes that are most likely to succeed, they can drastically reduce the number of experiments to be performed. Here we discuss the computational and experimental methods commonly used in drug design problems, focusing on the inverse relationship between the two, namely, the more accurate the computational predictions means the less experimental effort is needed for testing. Examples discussed include efforts to design selective analogs from toxin peptides targeting ion channels for treatment of autoimmune diseases and monoclonal antibodies which are the fastest growing class of therapeutic agents particularly for cancers and autoimmune diseases.
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Affiliation(s)
- Serdar Kuyucak
- School of Physics, University of Sydney, NSW 2006, Australia
- Corresponding author.
| | - Veysel Kayser
- Faculty of Pharmacy, University of Sydney, NSW 2006, Australia
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20
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Nekrasova OV, Volyntseva AD, Kudryashova KS, Novoseletsky VN, Lyapina EA, Illarionova AV, Yakimov SA, Korolkova YV, Shaitan KV, Kirpichnikov MP, Feofanov AV. Complexes of Peptide Blockers with Kv1.6 Pore Domain: Molecular Modeling and Studies with KcsA-Kv1.6 Channel. J Neuroimmune Pharmacol 2016; 12:260-276. [PMID: 27640211 DOI: 10.1007/s11481-016-9710-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/09/2016] [Indexed: 11/25/2022]
Abstract
Potassium voltage-gated Kv1.6 channel, which is distributed primarily in neurons of central and peripheral nervous systems, is of significant physiological importance. To date, several high-affinity Kv1.6-channel blockers are known, but the lack of selective ones among them hampers the studies of tissue localization and functioning of Kv1.6 channels. Here we present an approach to advanced understanding of interactions of peptide toxin blockers with a Kv1.6 pore. It combines molecular modeling studies and an application of a new bioengineering system based on a KcsA-Kv1.6 hybrid channel for the quantitative fluorescent analysis of blocker-channel interactions. Using this system we demonstrate that peptide toxins agitoxin 2, kaliotoxin1 and OSK1 have similar high affinity to the extracellular vestibule of the K+-conducting pore of Kv1.6, hetlaxin is a low-affinity ligand, whereas margatoxin and scyllatoxin do not bind to Kv1.6 pore. Binding of toxins to Kv1.6 pore has considerable inverse dependence on the ionic strength. Model structures of KcsA-Kv1.6 and Kv1.6 complexes with agitoxin 2, kaliotoxin 1 and OSK1 were obtained using homology modeling and molecular dynamics simulation. Interaction interfaces, which are formed by 15-19 toxin residues and 10 channel residues, are described and compared. Specific sites of Kv1.6 pore recognition are identified for targeting of peptide blockers. Analysis of interactions between agitoxin 2 derivatives with point mutations (S7K, S11G, L19S, R31G) and KcsA-Kv1.6 confirms reliability of the calculated complex structure.
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Affiliation(s)
- O V Nekrasova
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - A D Volyntseva
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - K S Kudryashova
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - V N Novoseletsky
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - E A Lyapina
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - A V Illarionova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - S A Yakimov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - Yu V Korolkova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - K V Shaitan
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia
| | - M P Kirpichnikov
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia
| | - A V Feofanov
- Biological Faculty, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119992, Russia. .,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997, Moscow, Russia.
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21
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Wu B, Wu BF, Feng YJ, Tao J, Ji YH. Mapping the Interaction Anatomy of BmP02 on Kv1.3 Channel. Sci Rep 2016; 6:29431. [PMID: 27403813 PMCID: PMC4941521 DOI: 10.1038/srep29431] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 06/16/2016] [Indexed: 12/21/2022] Open
Abstract
The potassium channel Kv 1.3 plays a vital part in the activation of T lymphocytes and is an attractive pharmacological target for autoimmune diseases. BmP02, a 28-residue peptide isolated from Chinese scorpion (Buthus martensi Karsch) venom, is a potent and selective Kv1.3 channel blocker. However, the mechanism through which BmP02 recognizes and inhibits the Kv1.3 channel is still unclear. In the present study, a complex molecular model of Kv1.3-BmP02 was developed by docking analysis and molecular dynamics simulations. From these simulations, it appears the large β-turn (residues 10–16) of BmP02 might be the binding interface with Kv 1.3. These results were confirmed by scanning alanine mutagenesis of BmP02, which identified His9, Lys11 and Lys13, which lie within BmP02’s β-turn, as key residues for interacting with Kv1.3. Based on these results and molecular modeling, two negatively charged residues of Kv1.3, D421 and D422, located in turret region, were predicted to act as the binding site for BmP02. Mutation of these residues reduced sensitivity of Kv 1.3 to BmP02 inhibition, suggesting that electrostatic interactions play a crucial role in Kv1.3-BmP02 interaction. This study revealed the molecular basis of Kv 1.3 recognition by BmP02 venom, and provides a novel interaction model for Kv channel-specific blocker complex, which may help guide future drug-design for Kv1.3-related channelopathies.
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Affiliation(s)
- B Wu
- Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Nanchen Road 333, Shanghai 200444, China
| | - B F Wu
- Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Nanchen Road 333, Shanghai 200444, China
| | - Y J Feng
- Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Nanchen Road 333, Shanghai 200444, China
| | - J Tao
- Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, 164 Lanxi road, Shanghai 200062, China
| | - Y H Ji
- Lab of Neuropharmacology and Neurotoxicology, Shanghai University, Nanchen Road 333, Shanghai 200444, China
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22
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Patel D, Mahdavi S, Kuyucak S. Computational Study of Binding of μ-Conotoxin GIIIA to Bacterial Sodium Channels NaVAb and NaVRh. Biochemistry 2016; 55:1929-38. [PMID: 26959170 DOI: 10.1021/acs.biochem.5b01324] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Structures of several voltage-gated sodium (NaV) channels from bacteria have been determined recently, but the same feat might not be achieved for the mammalian counterparts in the near future. Thus, at present, computational studies of the mammalian NaV channels have to be performed using homology models based on the bacterial crystal structures. A successful homology model for the mammalian NaV1.4 channel was recently constructed using the extensive mutation data for binding of μ-conotoxin GIIIA to NaV1.4, which was further validated through studies of binding of other μ-conotoxins and ion permeation. Understanding the similarities and differences between the bacterial and mammalian NaV channels is an important issue, and the NaV1.4-GIIIA system provides a good opportunity for such a comparison. To this end, we study the binding of GIIIA to the bacterial channels NaVAb and NaVRh. The complex structures are obtained using docking and molecular dynamics simulations, and the dissociation of GIIIA is studied through umbrella sampling simulations. The results are compared to those obtained from the NaV1.4-GIIIA system, and the differences in the binding modes arising from the changes in the selectivity filters are highlighted.
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Affiliation(s)
- Dharmeshkumar Patel
- School of Physics, University of Sydney , Sydney, New South Wales 2006, Australia
| | - Somayeh Mahdavi
- School of Physics, University of Sydney , Sydney, New South Wales 2006, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney , Sydney, New South Wales 2006, Australia
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23
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Ma G, Guan Y, Wang S, Xu H, Tao N. Study of Small-Molecule-Membrane Protein Binding Kinetics with Nanodisc and Charge-Sensitive Optical Detection. Anal Chem 2016; 88:2375-9. [PMID: 26752355 DOI: 10.1021/acs.analchem.5b04366] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Nanodisc technology provides membrane proteins with a nativelike lipid bilayer and much-needed solubility and enables in vitro quantification of membrane protein binding with ligands. However, it has been a challenge to measure interaction between small-molecule ligands and nanodisc-encapsulated membrane proteins, because the responses of traditional mass-based detection methods scale with the mass of the ligands. We have developed a charge-sensitive optical detection (CSOD) method for label-free measurement of the binding kinetics of low molecular mass ligands with nanodisc-encapsulated membrane proteins. This microplate-compatible method is sensitive to the charge instead of the mass of a ligand and is able to measure both large and small molecules in a potentially high-throughput format. Using CSOD, we measured the binding kinetics between peptide and small-molecule ligands and a nanodisc-encapsulated potassium ion channel protein, KcsA-Kv1.3. Both association and dissociation rate constants for these ligands are obtained for the first time. The CSOD results were validated by the consistency of the values with reported binding affinities. In addition, we found that CSOD can tolerate up to 3.9% dimethyl sulfoxide (DMSO) and up to 10% serum, which shows its compatibility with realistic sample conditions.
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Affiliation(s)
- Guangzhong Ma
- Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85281, United States
| | | | | | - Han Xu
- Therapeutic Discovery, Amgen Incorporated , Thousand Oaks, California 91320, United States
| | - Nongjian Tao
- Department of Chemistry and Biochemistry, Arizona State University , Tempe, Arizona 85281, United States
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24
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Computational Studies of Venom Peptides Targeting Potassium Channels. Toxins (Basel) 2015; 7:5194-211. [PMID: 26633507 PMCID: PMC4690127 DOI: 10.3390/toxins7124877] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/13/2015] [Accepted: 11/20/2015] [Indexed: 01/18/2023] Open
Abstract
Small peptides isolated from the venom of animals are potential scaffolds for ion channel drug discovery. This review article mainly focuses on the computational studies that have advanced our understanding of how various toxins interfere with the function of K+ channels. We introduce the computational tools available for the study of toxin-channel interactions. We then discuss how these computational tools have been fruitfully applied to elucidate the mechanisms of action of a wide range of venom peptides from scorpions, spiders, and sea anemone.
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25
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Murray JK, Qian YX, Liu B, Elliott R, Aral J, Park C, Zhang X, Stenkilsson M, Salyers K, Rose M, Li H, Yu S, Andrews KL, Colombero A, Werner J, Gaida K, Sickmier EA, Miu P, Itano A, McGivern J, Gegg CV, Sullivan JK, Miranda LP. Pharmaceutical Optimization of Peptide Toxins for Ion Channel Targets: Potent, Selective, and Long-Lived Antagonists of Kv1.3. J Med Chem 2015; 58:6784-802. [DOI: 10.1021/acs.jmedchem.5b00495] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Kristin L. Andrews
- Therapeutic
Discovery, Amgen Inc., 360 Binney Street, Cambridge, Massachusetts 02142, United States
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26
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Computational approaches for designing potent and selective analogs of peptide toxins as novel therapeutics. Future Med Chem 2015; 6:1645-58. [PMID: 25406005 DOI: 10.4155/fmc.14.98] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Peptide toxins provide valuable therapeutic leads for many diseases. As they bind to their targets with high affinity, potency is usually ensured. However, toxins also bind to off-target receptors, causing potential side effects. Thus, a major challenge in generating drugs from peptide toxins is ensuring their specificity for their intended targets. Computational methods can play an important role in solving such design problems through construction of accurate models of receptor-toxin complexes and calculation of binding free energies. Here we review the computational methods used for this purpose and their application to toxins targeting ion channels. We describe ShK and HsTX1 toxins, high-affinity blockers of the voltage-gated potassium channel Kv1.3, which could be developed as therapeutic agents for autoimmune diseases.
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Rashid MH, Heinzelmann G, Kuyucak S. Calculation of free energy changes due to mutations from alchemical free energy simulations. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2015. [DOI: 10.1142/s0219633615500236] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
How a mutation affects the binding free energy of a ligand is a fundamental problem in molecular biology/biochemistry with many applications in pharmacology and biotechnology, e.g. design of drugs and enzymes. Free energy change due to a mutation can be determined most accurately by performing alchemical free energy calculations in molecular dynamics (MD) simulations. Here we discuss the necessary conditions for success of free energy calculations using toxin peptides that bind to ion channels as examples. We show that preservation of the binding mode is an essential requirement but this condition is not always satisfied, especially when the mutation involves a charged residue. Otherwise problems with accuracy of results encountered in mutation of charged residues can be overcome by performing the mutation on the ligand in the binding site and bulk simultaneously and in the same system. The proposed method will be useful in improving the affinity and selectivity profiles of drug leads and enzymes via computational design and protein engineering.
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Affiliation(s)
- M. Harunur Rashid
- School of Physics, University of Sydney, New South Wales 2006, Australia
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Germano Heinzelmann
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, Santa Catarina, Brazil
| | - Serdar Kuyucak
- Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, Santa Catarina, Brazil
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Plectasin, first animal toxin-like fungal defensin blocking potassium channels through recognizing channel pore region. Toxins (Basel) 2015; 7:34-42. [PMID: 25568977 PMCID: PMC4303811 DOI: 10.3390/toxins7010034] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/24/2014] [Indexed: 12/04/2022] Open
Abstract
The potassium channels were recently found to be inhibited by animal toxin-like human β-defensin 2 (hBD2), the first defensin blocker of potassium channels. Whether there are other defensin blockers from different organisms remains an open question. Here, we reported the potassium channel-blocking plectasin, the first defensin blocker from a fungus. Based on the similar cysteine-stabilized alpha-beta (CSαβ) structure between plectasin and scorpion toxins acting on potassium channels, we found that plectasin could dose-dependently block Kv1.3 channel currents through electrophysiological experiments. Besides Kv1.3 channel, plectasin could less inhibit Kv1.1, Kv1.2, IKCa, SKCa3, hERG and KCNQ channels at the concentration of 1 μΜ. Using mutagenesis and channel activation experiments, we found that outer pore region of Kv1.3 channel was the binding site of plectasin, which is similar to the interacting site of Kv1.3 channel recognized by animal toxin blockers. Together, these findings not only highlight the novel function of plectasin as a potassium channel inhibitor, but also imply that defensins from different organisms functionally evolve to be a novel kind of potassium channel inhibitors.
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Systematic study of binding of μ-conotoxins to the sodium channel NaV1.4. Toxins (Basel) 2014; 6:3454-70. [PMID: 25529306 PMCID: PMC4280544 DOI: 10.3390/toxins6123454] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/01/2014] [Accepted: 12/10/2014] [Indexed: 01/25/2023] Open
Abstract
Voltage-gated sodium channels (NaV) are fundamental components of the nervous system. Their dysfunction is implicated in a number of neurological disorders, such as chronic pain, making them potential targets for the treatment of such disorders. The prominence of the NaV channels in the nervous system has been exploited by venomous animals for preying purposes, which have developed toxins that can block the NaV channels, thereby disabling their function. Because of their potency, such toxins could provide drug leads for the treatment of neurological disorders associated with NaV channels. However, most toxins lack selectivity for a given target NaV channel, and improving their selectivity profile among the NaV1 isoforms is essential for their development as drug leads. Computational methods will be very useful in the solution of such design problems, provided accurate models of the protein-ligand complex can be constructed. Using docking and molecular dynamics simulations, we have recently constructed a model for the NaV1.4-μ-conotoxin-GIIIA complex and validated it with the ample mutational data available for this complex. Here, we use the validated NaV1.4 model in a systematic study of binding other μ-conotoxins (PIIIA, KIIIA and BuIIIB) to NaV1.4. The binding mode obtained for each complex is shown to be consistent with the available mutation data and binding constants. We compare the binding modes of PIIIA, KIIIA and BuIIIB to that of GIIIA and point out the similarities and differences among them. The detailed information about NaV1.4-μ-conotoxin interactions provided here will be useful in the design of new NaV channel blocking peptides.
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Mahdavi S, Kuyucak S. Molecular dynamics study of binding of µ-conotoxin GIIIA to the voltage-gated sodium channel Na(v)1.4. PLoS One 2014; 9:e105300. [PMID: 25133704 PMCID: PMC4136838 DOI: 10.1371/journal.pone.0105300] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/22/2014] [Indexed: 12/27/2022] Open
Abstract
Homology models of mammalian voltage-gated sodium (NaV) channels based on the crystal structures of the bacterial counterparts are needed to interpret the functional data on sodium channels and understand how they operate. Such models would also be invaluable in structure-based design of therapeutics for diseases involving sodium channels such as chronic pain and heart diseases. Here we construct a homology model for the pore domain of the NaV1.4 channel and use the functional data for the binding of µ-conotoxin GIIIA to NaV1.4 to validate the model. The initial poses for the NaV1.4-GIIIA complex are obtained using the HADDOCK protein docking program, which are then refined in molecular dynamics simulations. The binding mode for the final complex is shown to be in broad agreement with the available mutagenesis data. The standard binding free energy, determined from the potential of mean force calculations, is also in good agreement with the experimental value. Because the pore domains of NaV1 channels are highly homologous, the model constructed for NaV1.4 will provide an excellent template for other NaV1 channels.
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Affiliation(s)
- Somayeh Mahdavi
- School of Physics, University of Sydney, Sydney, New South Wales, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales, Australia
- * E-mail:
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31
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Chen R, Chung SH. Binding modes of two scorpion toxins to the voltage-gated potassium channel kv1.3 revealed from molecular dynamics. Toxins (Basel) 2014; 6:2149-61. [PMID: 25054783 PMCID: PMC4113748 DOI: 10.3390/toxins6072149] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/08/2014] [Accepted: 07/10/2014] [Indexed: 12/13/2022] Open
Abstract
Molecular dynamics (MD) simulations are used to examine the binding modes of two scorpion toxins, margatoxin (MgTx) and hongotoxin (HgTx), to the voltage gated K+ channel, Kv1.3. Using steered MD simulations, we insert either Lys28 or Lys35 of the toxins into the selectivity filter of the channel. The MgTx-Kv1.3 complex is stable when the side chain of Lys35 from the toxin occludes the channel filter, suggesting that Lys35 is the pore-blocking residue for Kv1.3. In this complex, Lys28 of the toxin forms one additional salt bridge with Asp449 just outside the filter of the channel. On the other hand, HgTx forms a stable complex with Kv1.3 when the side chain of Lys28 but not Lys35 protrudes into the filter of the channel. A survey of all the possible favorable binding modes of HgTx-Kv1.3 is carried out by rotating the toxin at 3° intervals around the channel axis while the position of HgTx-Lys28 relative to the filter is maintained. We identify two possible favorable binding modes: HgTx-Arg24 can interact with either Asp433 or Glu420 on the vestibular wall of the channel. The dissociation constants calculated from the two binding modes of HgTx-Kv1.3 differ by approximately 20 fold, suggesting that the two modes are of similar energetics.
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Affiliation(s)
- Rong Chen
- Research School of Biology, Australian National University, Canberra, ACT 0200, Australia.
| | - Shin-Ho Chung
- Research School of Biology, Australian National University, Canberra, ACT 0200, Australia.
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Molecular dynamics simulations of scorpion toxin recognition by the Ca(2+)-activated potassium channel KCa3.1. Biophys J 2014; 105:1829-37. [PMID: 24138859 DOI: 10.1016/j.bpj.2013.08.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 08/26/2013] [Accepted: 08/30/2013] [Indexed: 02/06/2023] Open
Abstract
The Ca(2+)-activated channel of intermediate-conductance (KCa3.1) is a target for antisickling and immunosuppressant agents. Many small peptides isolated from animal venoms inhibit KCa3.1 with nanomolar affinities and are promising drug scaffolds. Although the inhibitory effect of peptide toxins on KCa3.1 has been examined extensively, the structural basis of toxin-channel recognition has not been understood in detail. Here, the binding modes of two selected scorpion toxins, charybdotoxin (ChTx) and OSK1, to human KCa3.1 are examined in atomic detail using molecular dynamics (MD) simulations. Employing a homology model of KCa3.1, we first determine conduction properties of the channel using Brownian dynamics and ascertain that the simulated results are in accord with experiment. The model structures of ChTx-KCa3.1 and OSK1-KCa3.1 complexes are then constructed using MD simulations biased with distance restraints. The ChTx-KCa3.1 complex predicted from biased MD is consistent with the crystal structure of ChTx bound to a voltage-gated K(+) channel. The dissociation constants (Kd) for the binding of both ChTx and OSK1 to KCa3.1 determined experimentally are reproduced within fivefold using potential of mean force calculations. Making use of the knowledge we gained by studying the ChTx-KCa3.1 complex, we attempt to enhance the binding affinity of the toxin by carrying out a theoretical mutagenesis. A mutant toxin, in which the positions of two amino acid residues are interchanged, exhibits a 35-fold lower Kd value for KCa3.1 than that of the wild-type. This study provides insight into the key molecular determinants for the high-affinity binding of peptide toxins to KCa3.1, and demonstrates the power of computational methods in the design of novel toxins.
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Sabogal-Arango A, Barreto GE, Ramírez-Sánchez D, González-Mendoza J, Barreto V, Morales L, González J. Computational Insights of the Interaction among Sea Anemones Neurotoxins and Kv1.3 Channel. Bioinform Biol Insights 2014; 8:73-81. [PMID: 24812496 PMCID: PMC3999815 DOI: 10.4137/bbi.s13403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 12/21/2022] Open
Abstract
Sea anemone neurotoxins are peptides that interact with Na(+) and K(+) channels, resulting in specific alterations on their functions. Some of these neurotoxins (1ROO, 1BGK, 2K9E, 1BEI) are important for the treatment of about 80 autoimmune disorders because of their specificity for Kv1.3 channel. The aim of this study was to identify the common residues among these neurotoxins by computational methods, and establish whether there is a pattern useful for the future generation of a treatment for autoimmune diseases. Our results showed eight new key common residues between the studied neurotoxins interacting with a histidine ring and the selectivity filter of the receptor, thus showing a possible pattern of interaction. This knowledge may serve as an input for the design of more promising drugs for autoimmune treatments.
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Affiliation(s)
- Angélica Sabogal-Arango
- Department of Nutrition and Biochemistry, Faculty of Science, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - George E Barreto
- Department of Nutrition and Biochemistry, Faculty of Science, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - David Ramírez-Sánchez
- Department of Pharmacy, Faculty of Science, Universidad Nacional de Colombia, Bogotá D.C., Colombia
| | - Juan González-Mendoza
- Department of Pharmacy, Faculty of Science, Universidad Nacional de Colombia, Bogotá D.C., Colombia
| | - Viviana Barreto
- Department of Nutrition and Biochemistry, Faculty of Science, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Ludis Morales
- Department of Nutrition and Biochemistry, Faculty of Science, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
| | - Janneth González
- Department of Nutrition and Biochemistry, Faculty of Science, Pontificia Universidad Javeriana, Bogotá D.C., Colombia
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Zhang H, Tan T, Hetényi C, Lv Y, van der Spoel D. Cooperative Binding of Cyclodextrin Dimers to Isoflavone Analogues Elucidated by Free Energy Calculations. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:7163-7173. [PMID: 24719673 PMCID: PMC3977494 DOI: 10.1021/jp412041d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/11/2014] [Indexed: 06/03/2023]
Abstract
Dimerization of cyclodextrin (CD) molecules is an elementary step in the construction of CD-based nanostructured materials. Cooperative binding of CD cavities to guest molecules facilitates the dimerization process and, consequently, the overall stability and assembly of CD nanostructures. In the present study, all three dimerization modes (head-to-head, head-to-tail, and tail-to-tail) of β-CD molecules and their binding to three isoflavone drug analogues (puerarin, daidzin, and daidzein) were investigated in explicit water surrounding using molecular dynamics simulations. Total and individual contributions from the binding partners and solvent environment to the thermodynamics of these binding reactions are quantified in detail using free energy calculations. Cooperative drug binding to two CD cavities gives an enhanced binding strength for daidzin and daidzein, whereas for puerarin no obvious enhancement is observed. Head-to-head dimerization yields the most stable complexes for inclusion of the tested isoflavones (templates) and may be a promising building block for construction of template-stabilized CD nanostructures. Compared to the case of CD monomers, the desolvation of CD dimers and entropy changes upon complexation prove to be influential factors of cooperative binding. Our results shed light on key points of the design of CD-based supramolecular assemblies. We also show that structure-based calculation of binding thermodynamics can quantify stabilization caused by cooperative effects in building blocks of nanostructured materials.
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Affiliation(s)
- Haiyang Zhang
- Beijing
Key Laboratory of Bioprocess, Department of Biochemical Engineering, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, Uppsala University, Husargatan 3, Box
596, SE-75124 Uppsala, Sweden
| | - Tianwei Tan
- Beijing
Key Laboratory of Bioprocess, Department of Biochemical Engineering, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - Csaba Hetényi
- Molecular
Biophysics Research Group, Hungarian Academy
of Sciences, Pázmány sétány
1/C, H-1117 Budapest, Hungary
| | - Yongqin Lv
- Beijing
Key Laboratory of Bioprocess, Department of Biochemical Engineering, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - David van der Spoel
- Uppsala
Center for Computational Chemistry, Science for Life Laboratory, Department
of Cell and Molecular Biology, Uppsala University, Husargatan 3, Box
596, SE-75124 Uppsala, Sweden
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35
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Rashid MH, Huq R, Tanner MR, Chhabra S, Khoo KK, Estrada R, Dhawan V, Chauhan S, Pennington MW, Beeton C, Kuyucak S, Norton RS. A potent and Kv1.3-selective analogue of the scorpion toxin HsTX1 as a potential therapeutic for autoimmune diseases. Sci Rep 2014; 4:4509. [PMID: 24676092 PMCID: PMC3968461 DOI: 10.1038/srep04509] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Accepted: 03/12/2014] [Indexed: 01/30/2023] Open
Abstract
HsTX1 toxin, from the scorpion Heterometrus spinnifer, is a 34-residue, C-terminally amidated peptide cross-linked by four disulfide bridges. Here we describe new HsTX1 analogues with an Ala, Phe, Val or Abu substitution at position 14. Complexes of HsTX1 with the voltage-gated potassium channels Kv1.3 and Kv1.1 were created using docking and molecular dynamics simulations, then umbrella sampling simulations were performed to construct the potential of mean force (PMF) of the ligand and calculate the corresponding binding free energy for the most stable configuration. The PMF method predicted that the R14A mutation in HsTX1 would yield a > 2 kcal/mol gain for the Kv1.3/Kv1.1 selectivity free energy relative to the wild-type peptide. Functional assays confirmed the predicted selectivity gain for HsTX1[R14A] and HsTX1[R14Abu], with an affinity for Kv1.3 in the low picomolar range and a selectivity of more than 2,000-fold for Kv1.3 over Kv1.1. This remarkable potency and selectivity for Kv1.3, which is significantly up-regulated in activated effector memory cells in humans, suggest that these analogues represent valuable leads in the development of therapeutics for autoimmune diseases.
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Affiliation(s)
- M Harunur Rashid
- 1] Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia [2] School of Physics, University of Sydney, New South Wales 2006, Australia
| | - Redwan Huq
- 1] Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA [2] Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mark R Tanner
- 1] Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA [2] Interdepartmental Graduate Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Keith K Khoo
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Rosendo Estrada
- Peptides International, 11621 Electron Drive, Louisville, KY 40299, USA
| | - Vikas Dhawan
- Peptides International, 11621 Electron Drive, Louisville, KY 40299, USA
| | - Satendra Chauhan
- Peptides International, 11621 Electron Drive, Louisville, KY 40299, USA
| | | | - Christine Beeton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Serdar Kuyucak
- School of Physics, University of Sydney, New South Wales 2006, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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Berkut AA, Usmanova DR, Peigneur S, Oparin PB, Mineev KS, Odintsova TI, Tytgat J, Arseniev AS, Grishin EV, Vassilevski AA. Structural similarity between defense peptide from wheat and scorpion neurotoxin permits rational functional design. J Biol Chem 2014; 289:14331-40. [PMID: 24671422 DOI: 10.1074/jbc.m113.530477] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In this study, we present the spatial structure of the wheat antimicrobial peptide (AMP) Tk-AMP-X2 studied using NMR spectroscopy. This peptide was found to adopt a disulfide-stabilized α-helical hairpin fold and therefore belongs to the α-hairpinin family of plant defense peptides. Based on Tk-AMP-X2 structural similarity to cone snail and scorpion potassium channel blockers, a mutant molecule, Tk-hefu, was engineered by incorporating the functionally important residues from κ-hefutoxin 1 onto the Tk-AMP-X2 scaffold. The designed peptide contained the so-called essential dyad of amino acid residues significant for channel-blocking activity. Electrophysiological studies showed that although the parent peptide Tk-AMP-X2 did not present any activity against potassium channels, Tk-hefu blocked Kv1.3 channels with similar potency (IC50 ∼ 35 μm) to κ-hefutoxin 1 (IC50 ∼ 40 μm). We conclude that α-hairpinins are attractive in their simplicity as structural templates, which may be used for functional engineering and drug design.
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Affiliation(s)
- Antonina A Berkut
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia, Moscow Institute of Physics and Technology (State University), Moscow 117303, Russia
| | - Dinara R Usmanova
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia, Moscow Institute of Physics and Technology (State University), Moscow 117303, Russia
| | - Steve Peigneur
- Laboratory of Toxicology and Pharmacology, University of Leuven, Leuven 3000, Belgium, and
| | - Peter B Oparin
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Konstantin S Mineev
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Tatyana I Odintsova
- N. I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Jan Tytgat
- Laboratory of Toxicology and Pharmacology, University of Leuven, Leuven 3000, Belgium, and
| | - Alexander S Arseniev
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Eugene V Grishin
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Alexander A Vassilevski
- From the M. M. Shemyakin and Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia,
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37
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Heinzelmann G, Chen PC, Kuyucak S. Computation of standard binding free energies of polar and charged ligands to the glutamate receptor GluA2. J Phys Chem B 2014; 118:1813-24. [PMID: 24479628 DOI: 10.1021/jp412195m] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Accurate calculation of the binding affinity of small molecules to proteins has the potential to become an important tool in rational drug design. In this study, we use the free energy perturbation (FEP) method with restraints to calculate the standard binding free energy of five ligands (ACPA, AMPA, CNQX, DNQX, and glutamate) to the glutamate receptor GluA2, which plays an essential role in synaptic transmission. To deal with the convergence problem in FEP calculations with charged ligands, we use a protocol where the ligand is coupled in the binding site while it is decoupled in bulk solution simultaneously. The contributions from the conformational, rotational, and translational entropies to the standard binding free energy are determined by applying/releasing respective restraints to the ligand in bulk/binding site. We also employ the confine-and-release approach, which helps to resolve convergence problems in FEP calculations. Our results are in good agreement with the experimental values for all five ligands, including the charged ones which are often problematic in FEP calculations. We also analyze the different contributions to the binding free energy of each ligand to GluA2 and discuss the nature of these interactions.
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38
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Rashid MH, Kuyucak S. Free Energy Simulations of Binding of HsTx1 Toxin to Kv1 Potassium Channels: the Basis of Kv1.3/Kv1.1 Selectivity. J Phys Chem B 2014; 118:707-16. [DOI: 10.1021/jp410950h] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- M. Harunur Rashid
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
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39
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Enhanced Sampling in Molecular Dynamics Using Metadynamics, Replica-Exchange, and Temperature-Acceleration. ENTROPY 2013. [DOI: 10.3390/e16010163] [Citation(s) in RCA: 291] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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40
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Rashid MH, Heinzelmann G, Huq R, Tajhya RB, Chang SC, Chhabra S, Pennington MW, Beeton C, Norton RS, Kuyucak S. A potent and selective peptide blocker of the Kv1.3 channel: prediction from free-energy simulations and experimental confirmation. PLoS One 2013; 8:e78712. [PMID: 24244345 PMCID: PMC3820677 DOI: 10.1371/journal.pone.0078712] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 09/23/2013] [Indexed: 12/27/2022] Open
Abstract
The voltage-gated potassium channel Kv1.3 is a well-established target for treatment of autoimmune diseases. ShK peptide from a sea anemone is one of the most potent blockers of Kv1.3 but its application as a therapeutic agent for autoimmune diseases is limited by its lack of selectivity against other Kv channels, in particular Kv1.1. Accurate models of Kv1.x-ShK complexes suggest that specific charge mutations on ShK could considerably enhance its specificity for Kv1.3. Here we evaluate the K18A mutation on ShK, and calculate the change in binding free energy associated with this mutation using the path-independent free energy perturbation and thermodynamic integration methods, with a novel implementation that avoids convergence problems. To check the accuracy of the results, the binding free energy differences were also determined from path-dependent potential of mean force calculations. The two methods yield consistent results for the K18A mutation in ShK and predict a 2 kcal/mol gain in Kv1.3/Kv1.1 selectivity free energy relative to wild-type peptide. Functional assays confirm the predicted selectivity gain for ShK[K18A] and suggest that it will be a valuable lead in the development of therapeutics for autoimmune diseases.
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Affiliation(s)
- M. Harunur Rashid
- School of Physics, University of Sydney, Sydney, New South Wales, Australia
| | | | - Redwan Huq
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Rajeev B. Tajhya
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shih Chieh Chang
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Sandeep Chhabra
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | | | - Christine Beeton
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- * E-mail: (RSN); (SK)
| | - Serdar Kuyucak
- School of Physics, University of Sydney, Sydney, New South Wales, Australia
- * E-mail: (RSN); (SK)
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Zhang H, Tan T, Hetényi C, van der Spoel D. Quantification of Solvent Contribution to the Stability of Noncovalent Complexes. J Chem Theory Comput 2013; 9:4542-51. [DOI: 10.1021/ct400404q] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Haiyang Zhang
- Beijing Key Laboratory
of Bioprocess, Department of Biochemical Engineering, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
- Science for Life
Laboratory, Department of Cell and Molecular Biology, Uppsala University, Husargatan
3, Box 596, SE-751 24 Uppsala, Sweden
| | - Tianwei Tan
- Beijing Key Laboratory
of Bioprocess, Department of Biochemical Engineering, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - Csaba Hetényi
- Molecular Biophysics
Research Group, Hungarian Academy of Sciences, Pázmány sétány 1/C, H-1117 Budapest, Hungary
| | - David van der Spoel
- Science for Life
Laboratory, Department of Cell and Molecular Biology, Uppsala University, Husargatan
3, Box 596, SE-751 24 Uppsala, Sweden
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42
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Gordon D, Chen R, Chung SH. Computational methods of studying the binding of toxins from venomous animals to biological ion channels: theory and applications. Physiol Rev 2013; 93:767-802. [PMID: 23589832 PMCID: PMC3768100 DOI: 10.1152/physrev.00035.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The discovery of new drugs that selectively block or modulate ion channels has great potential to provide new treatments for a host of conditions. One promising avenue revolves around modifying or mimicking certain naturally occurring ion channel modulator toxins. This strategy appears to offer the prospect of designing drugs that are both potent and specific. The use of computational modeling is crucial to this endeavor, as it has the potential to provide lower cost alternatives for exploring the effects of new compounds on ion channels. In addition, computational modeling can provide structural information and theoretical understanding that is not easily derivable from experimental results. In this review, we look at the theory and computational methods that are applicable to the study of ion channel modulators. The first section provides an introduction to various theoretical concepts, including force-fields and the statistical mechanics of binding. We then look at various computational techniques available to the researcher, including molecular dynamics, brownian dynamics, and molecular docking systems. The latter section of the review explores applications of these techniques, concentrating on pore blocker and gating modifier toxins of potassium and sodium channels. After first discussing the structural features of these channels, and their modes of block, we provide an in-depth review of past computational work that has been carried out. Finally, we discuss prospects for future developments in the field.
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Affiliation(s)
- Dan Gordon
- Research School of Biology, The Australian National University, Acton, ACT 0200, Australia.
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43
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Computational studies of marine toxins targeting ion channels. Mar Drugs 2013; 11:848-69. [PMID: 23528952 PMCID: PMC3705375 DOI: 10.3390/md11030848] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 01/30/2013] [Accepted: 02/07/2013] [Indexed: 12/18/2022] Open
Abstract
Toxins from marine animals offer novel drug leads for treatment of diseases involving ion channels. Computational methods could be very helpful in this endeavour in several ways, e.g., (i) constructing accurate models of the channel-toxin complexes using docking and molecular dynamics (MD) simulations; (ii) determining the binding free energies of toxins from umbrella sampling MD simulations; (iii) predicting the effect of mutations from free energy MD simulations. Using these methods, one can design new analogs of toxins with improved affinity and selectivity properties. Here we present a review of the computational methods and discuss their applications to marine toxins targeting potassium and sodium channels. Detailed examples from the potassium channel toxins—ShK from sea anemone and κ-conotoxin PVIIA—are provided to demonstrate capabilities of the computational methods to give accurate descriptions of the channel-toxin complexes and the energetics of their binding. An example is also given from sodium channel toxins (µ-conotoxin GIIIA) to illustrate the differences between the toxin binding modes in potassium and sodium channels.
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Mahdavi S, Kuyucak S. Why the Drosophila Shaker K+ channel is not a good model for ligand binding to voltage-gated Kv1 channels. Biochemistry 2013; 52:1631-40. [PMID: 23398369 DOI: 10.1021/bi301257p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The Drosophila Shaker K(+) channel is the first cloned voltage-gated potassium channel and has, therefore, played an important role in structural and functional studies of those channels. While such a role is well justified for ion permeation, it is not clear whether this also extends to ligand binding. Despite the high degree of homology among Shaker and Kv1 channels, κ-conotoxin PVIIA (κ-PVIIA) binds to Shaker with high affinity but not to Kv1 channels. Here we address this issue by studying binding of κ-PVIIA to Shaker and Kv1 channels using molecular dynamics (MD) simulations. The structures of the channel-toxin complexes are constructed via docking and refinement with MD. The binding mode of each complex is characterized and compared to available mutagenesis data to validate the complex models. The potential of mean force for dissociation of the Shaker-κ-PVIIA complex is calculated from umbrella sampling MD simulations, and the corresponding binding free energy is determined, which provides further validation of the complex structure. Comparison of the Shaker and Kv1 complex models shows that a few mutations in the turret and extended regions are sufficient to abolish the observed sensitivity of Shaker to κ-PVIIA. This study demonstrates that Shaker is not always a good model for Kv1 channels for ligand binding. It also provides insights into the binding of the toxin to potassium channels that will be useful for improving affinity and selectivity properties of Kv1 channels.
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Affiliation(s)
- Somayeh Mahdavi
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
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45
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Maffeo C, Bhattacharya S, Yoo J, Wells D, Aksimentiev A. Modeling and simulation of ion channels. Chem Rev 2012; 112:6250-84. [PMID: 23035940 PMCID: PMC3633640 DOI: 10.1021/cr3002609] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Christopher Maffeo
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - Swati Bhattacharya
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - Jejoong Yoo
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - David Wells
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
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46
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Zhang H, Tan T, Feng W, van der Spoel D. Molecular Recognition in Different Environments: β-Cyclodextrin Dimer Formation in Organic Solvents. J Phys Chem B 2012; 116:12684-93. [DOI: 10.1021/jp308416p] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Haiyang Zhang
- Department of Biochemical Engineering,
Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
- Department of Cell and Molecular
Biology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 596, SE-751 24 Uppsala, Sweden
| | - Tianwei Tan
- Department of Biochemical Engineering,
Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - Wei Feng
- Department of Biochemical Engineering,
Beijing Key Laboratory of Bioprocess, Beijing University of Chemical Technology, Box 53, 100029 Beijing, China
| | - David van der Spoel
- Department of Cell and Molecular
Biology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 596, SE-751 24 Uppsala, Sweden
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47
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A C-terminally amidated analogue of ShK is a potent and selective blocker of the voltage-gated potassium channel Kv1.3. FEBS Lett 2012; 586:3996-4001. [PMID: 23063513 DOI: 10.1016/j.febslet.2012.09.038] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 09/21/2012] [Accepted: 09/22/2012] [Indexed: 11/22/2022]
Abstract
ShK, a 35-residue peptide from a sea anemone, is a potent blocker of potassium channels. Here we describe a new ShK analogue with an additional C-terminus Lys residue and amide. ShK-K-amide is a potent blocker of Kv1.3 and, in contrast to ShK and ShK-amide, is selective for Kv1.3. To understand this selectivity, we created complexes of ShK-K-amide with Kv1.3 and Kv1.1 using docking and molecular dynamics simulations, then performed umbrella sampling simulations to construct the potential of mean force of the ligand and calculate the corresponding binding free energy for the most stable configuration. The results agree well with experimental data.
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48
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Conductance properties of the inwardly rectifying channel, Kir3.2: molecular and Brownian dynamics study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:471-8. [PMID: 23022491 DOI: 10.1016/j.bbamem.2012.09.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 09/17/2012] [Accepted: 09/20/2012] [Indexed: 02/08/2023]
Abstract
Using the recently unveiled crystal structure, and molecular and Brownian dynamics simulations, we elucidate several conductance properties of the inwardly rectifying potassium channel, Kir3.2, which is implicated in cardiac and neurological disorders. We show that the pore is closed by a hydrophobic gating mechanism similar to that observed in Kv1.2. Once open, potassium ions move into, but not out of, the cell. The asymmetrical current-voltage relationship arises from the lack of negatively charged residues at the narrow intracellular mouth of the channel. When four phenylalanine residues guarding the intracellular gate are mutated to glutamate residues, the channel no longer shows inward rectification. Inward rectification is restored in the mutant Kir3.2 when it becomes blocked by intracellular Mg(2+). Tertiapin, a polypeptide toxin isolated from the honey bee, is known to block several subtypes of the inwardly rectifying channels with differing affinities. We identify critical residues in the toxin and Kir3.2 for the formation of the stable complex. A lysine residue of tertiapin protrudes into the selectivity filter of Kir3.2, while two other basic residues of the toxin form hydrogen bonds with acidic residues located just outside the channel entrance. The depth of the potential of mean force encountered by tertiapin is -16.1kT, thus indicating that the channel will be half-blocked by 0.4μM of the toxin.
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