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Matsumura K, Yokogawa M, Osawa M. Peptide Toxins Targeting KV Channels. Handb Exp Pharmacol 2021; 267:481-505. [PMID: 34117930 DOI: 10.1007/164_2021_500] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A number of peptide toxins isolated from animals target potassium ion (K+) channels. Many of them are particularly known to inhibit voltage-gated K+ (KV) channels and are mainly classified into pore-blocking toxins or gating-modifier toxins. Pore-blocking toxins directly bind to the ion permeation pores of KV channels, thereby physically occluding them. In contrast, gating-modifier toxins bind to the voltage-sensor domains of KV channels, modulating their voltage-dependent conformational changes. These peptide toxins are useful molecular tools in revealing the structure-function relationship of KV channels and have potential for novel treatments for diseases related to KV channels. This review focuses on the inhibition mechanism of pore-blocking and gating-modifier toxins that target KV channels.
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Affiliation(s)
- Kazuki Matsumura
- Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan
| | - Mariko Yokogawa
- Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, Keio University, Tokyo, Japan.
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2
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Li C, Jia Z, Chakravorty A, Pahari S, Peng Y, Basu S, Koirala M, Panday SK, Petukh M, Li L, Alexov E. DelPhi Suite: New Developments and Review of Functionalities. J Comput Chem 2019; 40:2502-2508. [PMID: 31237360 PMCID: PMC6771749 DOI: 10.1002/jcc.26006] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/07/2019] [Accepted: 06/09/2019] [Indexed: 12/25/2022]
Abstract
Electrostatic potential, energies, and forces affect virtually any process in molecular biology, however, computing these quantities is a difficult task due to irregularly shaped macromolecules and the presence of water. Here, we report a new edition of the popular software package DelPhi along with describing its functionalities. The new DelPhi is a C++ object-oriented package supporting various levels of multiprocessing and memory distribution. It is demonstrated that multiprocessing results in significant improvement of computational time. Furthermore, for computations requiring large grid size (large macromolecular assemblages), the approach of memory distribution is shown to reduce the requirement of RAM and thus permitting large-scale modeling to be done on Linux clusters with moderate architecture. The new release comes with new features, whose functionalities and applications are described as well. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc.
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Affiliation(s)
- Chuan Li
- Department of MathematicsWest Chester University of PennsylvaniaWest ChesterPennsylvania19383
| | - Zhe Jia
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
| | - Arghya Chakravorty
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
| | - Swagata Pahari
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
| | - Yunhui Peng
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
| | - Sankar Basu
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
| | - Mahesh Koirala
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
| | | | - Marharyta Petukh
- Department of BiologyPresbyterian CollegeClintonSouth Carolina29325
| | - Lin Li
- Department of PhysicsUniversity of Texas at EI PasoTexas79968
| | - Emil Alexov
- Department of Physics and AstronomyClemson UniversityClemsonSouth Carolina29634
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3
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Morales Duque H, Campos Dias S, Franco OL. Structural and Functional Analyses of Cone Snail Toxins. Mar Drugs 2019; 17:md17060370. [PMID: 31234371 PMCID: PMC6628382 DOI: 10.3390/md17060370] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 06/16/2019] [Accepted: 06/17/2019] [Indexed: 12/12/2022] Open
Abstract
Cone snails are marine gastropod mollusks with one of the most powerful venoms in nature. The toxins, named conotoxins, must act quickly on the cone snails´ prey due to the fact that snails are extremely slow, reducing their hunting capability. Therefore, the characteristics of conotoxins have become the object of investigation, and as a result medicines have been developed or are in the trialing process. Conotoxins interact with transmembrane proteins, showing specificity and potency. They target ion channels and ionotropic receptors with greater regularity, and when interaction occurs, there is immediate physiological decompensation. In this review we aimed to evaluate the structural features of conotoxins and the relationship with their target types.
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Affiliation(s)
- Harry Morales Duque
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Simoni Campos Dias
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
| | - Octávio Luiz Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF 70.790-160, Brazil.
- S-inova Biotech, Programa de Pós-Graduação em Biotecnologia, Universidade Católica Dom Bosco, Campo Grande-MS 79.117-900, Brazil.
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4
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Mansbach RA, Travers T, McMahon BH, Fair JM, Gnanakaran S. Snails In Silico: A Review of Computational Studies on the Conopeptides. Mar Drugs 2019; 17:E145. [PMID: 30832207 PMCID: PMC6471681 DOI: 10.3390/md17030145] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/21/2019] [Accepted: 02/22/2019] [Indexed: 12/26/2022] Open
Abstract
Marine cone snails are carnivorous gastropods that use peptide toxins called conopeptides both as a defense mechanism and as a means to immobilize and kill their prey. These peptide toxins exhibit a large chemical diversity that enables exquisite specificity and potency for target receptor proteins. This diversity arises in terms of variations both in amino acid sequence and length, and in posttranslational modifications, particularly the formation of multiple disulfide linkages. Most of the functionally characterized conopeptides target ion channels of animal nervous systems, which has led to research on their therapeutic applications. Many facets of the underlying molecular mechanisms responsible for the specificity and virulence of conopeptides, however, remain poorly understood. In this review, we will explore the chemical diversity of conopeptides from a computational perspective. First, we discuss current approaches used for classifying conopeptides. Next, we review different computational strategies that have been applied to understanding and predicting their structure and function, from machine learning techniques for predictive classification to docking studies and molecular dynamics simulations for molecular-level understanding. We then review recent novel computational approaches for rapid high-throughput screening and chemical design of conopeptides for particular applications. We close with an assessment of the state of the field, emphasizing important questions for future lines of inquiry.
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Affiliation(s)
- Rachael A Mansbach
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Timothy Travers
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Benjamin H McMahon
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - Jeanne M Fair
- Biosecurity and Public Health Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | - S Gnanakaran
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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5
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Zhao Y, Chen Z, Cao Z, Li W, Wu Y. Defensins, a novel type of animal toxin-like potassium channel inhibitor. Toxicon 2018; 157:101-105. [PMID: 30472109 DOI: 10.1016/j.toxicon.2018.11.304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 11/03/2018] [Accepted: 11/19/2018] [Indexed: 12/29/2022]
Abstract
The classical potassium channel inhibitors are toxin peptides from venomous animals, and whether there are peptide inhibitors from other species is an open question. Due to both the independent and interdependent relationships between the spear (peptide inhibitors) and the shield (potassium channels), human defensins were first identified by our group as endogenous potassium channel inhibitors. Encouraged by the discovery of human defensins as potassium channel inhibitors, defensins from invertebrates and fungi were successively found by our group to be potassium channel inhibitors. In addition, a plant defensin was reported to be a potassium channel inhibitor. Since defensins are widely produced by vertebrate, invertebrate, plant and fungi species, the recent work established a new research field on defensin-potassium channel interactions. Here, we review the current work on defensins from vertebrate, invertebrate, plant and fungi species as inhibitors of potassium channels and discuss future work in this research field.
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Affiliation(s)
- Yonghui Zhao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Zongyun Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China.
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6
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Kwon S, Bosmans F, Kaas Q, Cheneval O, Conibear AC, Rosengren KJ, Wang CK, Schroeder CI, Craik DJ. Efficient enzymatic cyclization of an inhibitory cystine knot-containing peptide. Biotechnol Bioeng 2016; 113:2202-12. [PMID: 27093300 DOI: 10.1002/bit.25993] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 04/04/2016] [Accepted: 04/11/2016] [Indexed: 01/01/2023]
Abstract
Disulfide-rich peptides isolated from cone snails are of great interest as drug leads due to their high specificity and potency toward therapeutically relevant ion channels and receptors. They commonly contain the inhibitor cystine knot (ICK) motif comprising three disulfide bonds forming a knotted core. Here we report the successful enzymatic backbone cyclization of an ICK-containing peptide κ-PVIIA, a 27-amino acid conopeptide from Conus purpurascens, using a mutated version of the bacterial transpeptidase, sortase A. Although a slight loss of activity was observed compared to native κ-PVIIA, cyclic κ-PVIIA is a functional peptide that inhibits the Shaker voltage-gated potassium (Kv) channel. Molecular modeling suggests that the decrease in potency may be related to the loss of crucial, but previously unidentified electrostatic interactions between the N-terminus of the peptide and the Shaker channel. This hypothesis was confirmed by testing an N-terminally acetylated κ-PVIIA, which shows a similar decrease in activity. We also investigated the conformational dynamics and hydrogen bond network of cyc-PVIIA, both of which are important factors to be considered for successful cyclization of peptides. We found that cyc-PVIIA has the same conformational dynamics, but different hydrogen bond network compared to those of κ-PVIIA. The ability to efficiently cyclize ICK peptides using sortase A will enable future protein engineering for this class of peptides and may help in the development of novel therapeutic molecules. Biotechnol. Bioeng. 2016;113: 2202-2212. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Soohyun Kwon
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia
| | - Frank Bosmans
- Department of Physiology and Solomon H Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Quentin Kaas
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia
| | - Olivier Cheneval
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia
| | - Anne C Conibear
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia
| | - K Johan Rosengren
- The University of Queensland, School of Biomedical Sciences, Brisbane, Qld, Australia
| | - Conan K Wang
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia
| | - Christina I Schroeder
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia.
| | - David J Craik
- The University of Queensland, Institute for Molecular Bioscience, Brisbane, Qld, 4072, Australia.
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7
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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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8
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Fang RH, Luk BT, Hu CMJ, Zhang L. Engineered nanoparticles mimicking cell membranes for toxin neutralization. Adv Drug Deliv Rev 2015; 90:69-80. [PMID: 25868452 DOI: 10.1016/j.addr.2015.04.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/08/2015] [Accepted: 04/01/2015] [Indexed: 11/27/2022]
Abstract
Protein toxins secreted from pathogenic bacteria and venomous animals rely on multiple mechanisms to overcome the cell membrane barrier to inflict their virulence effect. A promising therapeutic concept toward developing a broadly applicable anti-toxin platform is to administer cell membrane mimics as decoys to sequester these virulence factors. As such, lipid membrane-based nanoparticulates are an ideal candidate given their structural similarity to cellular membranes. This article reviews the virulence mechanisms employed by toxins at the cell membrane interface and highlights the application of cell-membrane mimicking nanoparticles as toxin decoys for systemic detoxification. In addition, the implication of particle/toxin nanocomplexes in the development of toxoid vaccines is discussed.
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9
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Chen Z, Hu Y, Hong J, Hu J, Yang W, Xiang F, Yang F, Xie Z, Cao Z, Li W, Lin D, Wu Y. Toxin acidic residue evolutionary function-guided design of de novo peptide drugs for the immunotherapeutic target, the Kv1.3 channel. Sci Rep 2015; 5:9881. [PMID: 25955787 PMCID: PMC4424837 DOI: 10.1038/srep09881] [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: 11/26/2014] [Accepted: 03/24/2015] [Indexed: 12/25/2022] Open
Abstract
During the long-term evolution of animal toxins acting on potassium channels, the acidic residues can orientate the toxin binding interfaces by adjusting the molecular polarity. Based on the evolutionary function of toxin acidic residues, de novo peptide drugs with distinct binding interfaces were designed for the immunotherapeutic target, the Kv1.3 channel. Using a natural basic toxin, BmKTX, as a template, which contains 2 acidic residues (Asp19 and Asp33), we engineered two new peptides BmKTX-19 with 1 acidic residue (Asp33), and BmKTX-196 with 2 acidic residues (Asp6 and Asp33) through only adjusting acidic residue distribution for reorientation of BmKTX binding interface. Pharmacological experiments indicated that BmKTX-19 and BmKTX-196 peptides were specific inhibitors of the Kv1.3 channel and effectively suppressed cytokine secretion. In addition to the structural similarity between the designed and native peptides, both experimental alanine-scanning mutagenesis and computational simulation further indicated that the binding interface of wild-type BmKTX was successfully reoriented in BmKTX-19 and BmKTX-196, which adopted distinct toxin surfaces as binding interfaces. Together, these findings indicate not only the promising prospect of BmKTX-19 and BmKTX-196 as drug candidates but also the desirable feasibility of the evolution-guided peptide drug design for discovering numerous peptide drugs for the Kv1.3 channel.
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Affiliation(s)
- Zongyun Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Youtian Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jing Hong
- College of Biological Science and Technology, Fuzhou University, Fuzhou 350108, China
| | - Jun Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Weishan Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Fang Xiang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Fan Yang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zili Xie
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zhijian Cao
- 1] State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China [2] Center for BioDrug Research, Wuhan University, Wuhan 430072, China
| | - Wenxin Li
- 1] State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China [2] Center for BioDrug Research, Wuhan University, Wuhan 430072, China
| | - Donghai Lin
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yingliang Wu
- 1] State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China [2] Center for BioDrug Research, Wuhan University, Wuhan 430072, China
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10
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Akondi KB, Muttenthaler M, Dutertre S, Kaas Q, Craik DJ, Lewis RJ, Alewood PF. Discovery, synthesis, and structure-activity relationships of conotoxins. Chem Rev 2014; 114:5815-47. [PMID: 24720541 PMCID: PMC7610532 DOI: 10.1021/cr400401e] [Citation(s) in RCA: 237] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Sébastien Dutertre
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Quentin Kaas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - David J Craik
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia
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11
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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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12
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Grabowsky S, Jayatilaka D, Fink RF, Schirmeister T, Engels B. Can Experimental Electron-Density Studies be Used as a Tool to Predict Biologically Relevant Properties of Low-Molecular Weight Enzyme Ligands? Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201200518] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Hu J, Qiu S, Yang F, Cao Z, Li W, Wu Y. Unique mechanism of the interaction between honey bee toxin TPNQ and rKir1.1 potassium channel explored by computational simulations: insights into the relative insensitivity of channel towards animal toxins. PLoS One 2013; 8:e67213. [PMID: 23874410 PMCID: PMC3707903 DOI: 10.1371/journal.pone.0067213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 05/15/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The 21-residue compact tertiapin-Q (TPNQ) toxin, a derivative of honey bee toxin tertiapin (TPN), is a potent blocker of inward-rectifier K(+) channel subtype, rat Kir1.1 (rKir1.1) channel, and their interaction mechanism remains unclear. PRINCIPAL FINDINGS Based on the flexible feature of potassium channel turrets, a good starting rKir1.1 channel structure was modeled for the accessibility of rKir1.1 channel turrets to TPNQ toxin. In combination with experimental alanine scanning mutagenesis data, computational approaches were further used to obtain a reasonable TPNQ toxin-rKir1.1 channel complex structure, which was completely different from the known binding modes between animal toxins and potassium channels. TPNQ toxin mainly adopted its helical domain as the channel-interacting surface together with His12 as the pore-blocking residue. The important Gln13 residue mainly contacted channel residues near the selectivity filter, and Lys20 residue was surrounded by a polar "groove" formed by Arg118, Thr119, Glu123, and Asn124 in the channel turret. On the other hand, four turrets of rKir1.1 channel gathered to form a narrow pore entryway for TPNQ toxin recognition. The Phe146 and Phe148 residues in the channel pore region formed strong hydrophobic protrusions, and produced dominant nonpolar interactions with toxin residues. These specific structure features of rKir1.1 channel vestibule well matched the binding of potent TPNQ toxin, and likely restricted the binding of the classical animal toxins. CONCLUSIONS/SIGNIFICANCE The TPNQ toxin-rKir1.1 channel complex structure not only revealed their unique interaction mechanism, but also would highlight the diverse animal toxin-potassium channel interactions, and elucidate the relative insensitivity of rKir1.1 channel towards animal toxins.
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Affiliation(s)
- Jun Hu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, PR China
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14
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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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15
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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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16
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Huang CJ, Schild L, Moczydlowski EG. Use-dependent block of the voltage-gated Na(+) channel by tetrodotoxin and saxitoxin: effect of pore mutations that change ionic selectivity. ACTA ACUST UNITED AC 2013; 140:435-54. [PMID: 23008436 PMCID: PMC3457692 DOI: 10.1085/jgp.201210853] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated Na(+) channels (NaV channels) are specifically blocked by guanidinium toxins such as tetrodotoxin (TTX) and saxitoxin (STX) with nanomolar to micromolar affinity depending on key amino acid substitutions in the outer vestibule of the channel that vary with NaV gene isoforms. All NaV channels that have been studied exhibit a use-dependent enhancement of TTX/STX affinity when the channel is stimulated with brief repetitive voltage depolarizations from a hyperpolarized starting voltage. Two models have been proposed to explain the mechanism of TTX/STX use dependence: a conformational mechanism and a trapped ion mechanism. In this study, we used selectivity filter mutations (K1237R, K1237A, and K1237H) of the rat muscle NaV1.4 channel that are known to alter ionic selectivity and Ca(2+) permeability to test the trapped ion mechanism, which attributes use-dependent enhancement of toxin affinity to electrostatic repulsion between the bound toxin and Ca(2+) or Na(+) ions trapped inside the channel vestibule in the closed state. Our results indicate that TTX/STX use dependence is not relieved by mutations that enhance Ca(2+) permeability, suggesting that ion-toxin repulsion is not the primary factor that determines use dependence. Evidence now favors the idea that TTX/STX use dependence arises from conformational coupling of the voltage sensor domain or domains with residues in the toxin-binding site that are also involved in slow inactivation.
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17
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Lewis RJ, Dutertre S, Vetter I, Christie MJ. Conus Venom Peptide Pharmacology. Pharmacol Rev 2012; 64:259-98. [DOI: 10.1124/pr.111.005322] [Citation(s) in RCA: 323] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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18
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In silico analysis of conformational changes induced by mutation of aromatic binding residues: consequences for drug binding in the hERG K+ channel. PLoS One 2011; 6:e28778. [PMID: 22194911 PMCID: PMC3240635 DOI: 10.1371/journal.pone.0028778] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 11/15/2011] [Indexed: 01/24/2023] Open
Abstract
Pharmacological inhibition of cardiac hERG K+ channels is associated with increased risk of lethal arrhythmias. Many drugs reduce hERG current by directly binding to the channel, thereby blocking ion conduction. Mutation of two aromatic residues (F656 and Y652) substantially decreases the potency of numerous structurally diverse compounds. Nevertheless, some drugs are only weakly affected by mutation Y652A. In this study we utilize molecular dynamics simulations and docking studies to analyze the different effects of mutation Y652A on a selected number of hERG blockers. MD simulations reveal conformational changes in the binding site induced by mutation Y652A. Loss of π-π-stacking between the two aromatic residues induces a conformational change of the F656 side chain from a cavity facing to cavity lining orientation. Docking studies and MD simulations qualitatively reproduce the diverse experimentally observed modulatory effects of mutation Y652A and provide a new structural interpretation for the sensitivity differences.
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19
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Jin L, Wu Y. Molecular mechanism of δ-dendrotoxin-potassium channel recognition explored by docking and molecular dynamic simulations. J Mol Recognit 2011; 24:101-7. [PMID: 21194120 DOI: 10.1002/jmr.1031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
δ-Dendrotoxin, isolated from mamba snake venom, has 57 residues cross-linked by three disulfide bridges. The protein shares a pharmacological activity with other animal toxins, the potent blockade of potassium channels, but is structurally unrelated to toxins of different species. We employed alanine-scanning mutagenesis to explore the molecular mechanism of δ-dendrotoxin binding to potassium channels, using protein-protein docking and molecular dynamic simulations. In our reasonable model of the δ-dendrotoxin-ShaKv1.1 complex, δ-dendrotoxin interacted mainly with the N-terminal region and the turn of two antiparallel β-sheets of the channel. This binding mode could well explain the functional roles of critical residues in δ-dendrotoxin and the ShaKv1.1 channel. Structural analysis indicated that the critical Lys6 residue of δ-dendrotoxin plugged its side chain into a channel selectivity filter. Another two critical δ-dendrotoxin residues, Lys3 and Arg10, were found to contact channel residues through strong polar and nonpolar interactions, especially salt-bridge interactions. As for the ShaKv1.1 channel, the channel turrets were found in the "half-open state," and two of four Glu423 in the turrets of the channel B and D chains could interact, respectively, with Lys3 and Lys26 of δ-dendrotoxin through electrostatic interactions. The essential Asp431 channel residue was found to associate electrostatically with Arg10 of δ-dendrotoxin, and a critical Tyr449 channel residue was just under the channel-interacting surface of δ-dendrotoxin. Together, these novel data may accelerate the structure-function research of toxins in the dendrotoxin family and be of significant value in revealing the diverse interactions between animal toxins and potassium channels.
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Affiliation(s)
- Ling Jin
- Department of Chemistry, School of Natural Science, Wuhan University of Technology, Wuhan, Hubei 430070, P.R. China.
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20
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Schreiber G, Haran G, Zhou HX. Fundamental aspects of protein-protein association kinetics. Chem Rev 2010; 109:839-60. [PMID: 19196002 DOI: 10.1021/cr800373w] [Citation(s) in RCA: 559] [Impact Index Per Article: 39.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- G Schreiber
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, 76100, Israel.
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21
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Abstract
Venoms of snakes, scorpions, spiders, insects, sea anemones, and cone snails are complex mixtures of mostly peptides and small proteins that have evolved for prey capture and/or defense. These deadly animals have long fascinated scientists and the public. Early studies isolated lethal components in the search for cures and understanding of their mechanisms of action. Ion channels have emerged as targets for many venom peptides, providing researchers highly selective and potent molecular probes that have proved invaluable in unraveling ion channel structure and function. This minireview highlights molecular details of their toxin-receptor interactions and opportunities for development of peptide therapeutics.
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Affiliation(s)
- Sébastien Dutertre
- From Atheris Laboratories, CH-1233 Bernex-Geneva, Switzerland and
- the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4067, Australia
| | - Richard J. Lewis
- the Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland 4067, Australia
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22
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Han S, Yin S, Yi H, Mouhat S, Qiu S, Cao Z, Sabatier JM, Wu Y, Li W. Protein−Protein Recognition Control by Modulating Electrostatic Interactions. J Proteome Res 2010; 9:3118-25. [DOI: 10.1021/pr100027k] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Song Han
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Shijin Yin
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Hong Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Stéphanie Mouhat
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Su Qiu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Jean-Marc Sabatier
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, and ERT 62 ≪Ingénierie des peptides à visée thérapeutique≫, Université de la Méditerranée - Ambrilia Biopharma S.A., Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cédex 20, France
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23
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Cervenka R, Zarrabi T, Lukacs P, Todt H. The outer vestibule of the Na+ channel-toxin receptor and modulator of permeation as well as gating. Mar Drugs 2010; 8:1373-93. [PMID: 20479982 PMCID: PMC2866490 DOI: 10.3390/md8041373] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 03/31/2010] [Accepted: 04/19/2010] [Indexed: 12/19/2022] Open
Abstract
The outer vestibule of voltage-gated Na(+) channels is formed by extracellular loops connecting the S5 and S6 segments of all four domains ("P-loops"), which fold back into the membrane. Classically, this structure has been implicated in the control of ion permeation and in toxin blockage. However, conformational changes of the outer vestibule may also result in alterations in gating, as suggested by several P-loop mutations that gave rise to gating changes. Moreover, partial pore block by mutated toxins may reverse gating changes induced by mutations. Therefore, toxins that bind to the outer vestibule can be used to modulate channel gating.
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Affiliation(s)
| | | | - Peter Lukacs
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; E-Mails:
(R.C.);
(T.Z.);
(P.L.)
| | - Hannes Todt
- Institute of Pharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria; E-Mails:
(R.C.);
(T.Z.);
(P.L.)
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24
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Ishikawa K, Yamamoto T, Asakawa M, Tezuka Y. Effective Synthesis of Polymer Catenanes by Cooperative Electrostatic/Hydrogen-Bonding Self-Assembly and Covalent Fixation. Macromolecules 2009. [DOI: 10.1021/ma902031j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kazuyuki Ishikawa
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Takuya Yamamoto
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Masumi Asakawa
- Nanotube Research Center, National Instutute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Yasuyuki Tezuka
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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25
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Qiu S, Yi H, Liu H, Cao Z, Wu Y, Li W. Molecular Information of Charybdotoxin Blockade in the Large Conductance Calcium-activated Potassium Channel. J Chem Inf Model 2009; 49:1831-8. [DOI: 10.1021/ci900025n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Su Qiu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Hong Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Hui Liu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, PR China
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26
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Spontaneous conformational change and toxin binding in alpha7 acetylcholine receptor: insight into channel activation and inhibition. Proc Natl Acad Sci U S A 2008; 105:8280-5. [PMID: 18541920 DOI: 10.1073/pnas.0710530105] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nicotinic AChRs (nAChRs) represent a paradigm for ligand-gated ion channels. Despite intensive studies over many years, our understanding of the mechanisms of activation and inhibition for nAChRs is still incomplete. Here, we present molecular dynamics (MD) simulations of the alpha7 nAChR ligand-binding domain, both in apo form and in alpha-Cobratoxin-bound form, starting from the respective homology models built on crystal structures of the acetylcholine-binding protein. The toxin-bound form was relatively stable, and its structure was validated by calculating mutational effects on the toxin-binding affinity. However, in the apo form, one subunit spontaneously moved away from the conformation of the other four subunits. This motion resembles what has been proposed for leading to channel opening. At the top, the C loop and the adjacent beta7-beta8 loop swing downward and inward, whereas at the bottom, the F loop and the C terminus of beta10 swing in the opposite direction. These swings appear to tilt the whole subunit clockwise. The resulting changes in solvent accessibility show strong correlation with experimental results by the substituted cysteine accessibility method upon addition of acetylcholine. Our MD simulation results suggest a mechanistic model in which the apo form, although predominantly sampling the "closed" state, can make excursions into the "open" state. The open state has high affinity for agonists, leading to channel activation, whereas the closed state upon distortion has high affinity for antagonists, leading to inhibition.
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27
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Yi H, Qiu S, Cao Z, Wu Y, Li W. Molecular basis of inhibitory peptide maurotoxin recognizing Kv1.2 channel explored by ZDOCK and molecular dynamic simulations. Proteins 2008; 70:844-54. [PMID: 17729277 DOI: 10.1002/prot.21706] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Inhibitory peptide-channel interactions have been utilized to characterize both channels and peptides; however, the fundamental basis for these interactions remains elusive. Here, combined computation methods were employed to study the specific binding of maurotoxin (MTX) peptide to Kv1.2 channel. In the first stage, numerous predicted complexes were generated by docking an ensemble of all 35 NMR conformations of MTX to Kv1.2 channel with ZDOCK program. Then the resulted complexes were clustered and classified into four main binding modes, based on experimental information and interaction energy analysis after the energy minimization and molecular dynamics (MD) simulations. By examining the stability of the plausible candidates through unrestrained MD simulations and calculation of the binding free energies, a final reasonable MTX-Kv1.2 complex was identified, with an overall high degree of correlation between the calculation and experiment on mutational effects. In the obtained complex structure model, MTX mainly used its beta-sheet domains to associate the channel mouth instead of the well-recognized functionally important S5P linkers of Kv1.2 channel. Structure analysis characterized that the most essential Tyr(32) residue of MTX was surrounded by a "pocket" formed by many nonpolar and polar residues of Kv1.2 channel, and revealed a pore-blocking Lys(23) and an important Lys(7) stabilized by strong electrostatic interactions with Asp(379) of Kv1.2. Furthermore, a stepwise structural arrangement for both ligand and receptor was found to accompany the tighter interaction of MTX into the target channel. The starting conformation of MTX, the side-chain conformation of the most important residue Tyr(32), and proper introduction of flexibility for candidate complexes were demonstrated to be considerably important factors for obtaining the final reasonable complex structure model. All these findings should not only be helpful for identifying more plausible K(+) channel-inhibitory peptide complex structures, but also provide intrinsically valuable structural biology information to interpret binding affinities, specificities, and diversity of K(+) channel-nature toxin interactions.
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Affiliation(s)
- Hong Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, People's Republic of China
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28
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Recanatini M, Cavalli A, Masetti M. Modeling hERG and its Interactions with Drugs: Recent Advances in Light of Current Potassium Channel Simulations. ChemMedChem 2008; 3:523-35. [DOI: 10.1002/cmdc.200700264] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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29
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Tjong H, Zhou HX. On the Dielectric Boundary in Poisson-Boltzmann Calculations. J Chem Theory Comput 2008; 4:507-514. [PMID: 23304097 DOI: 10.1021/ct700319x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
In applying the Poisson-Boltzmann (PB) equation for calculating the electrostatic free energies of solute molecules, an open question is how to specify the boundary between the low-dielectric solute and the high-dielectric solvent. Two common specifications of the dielectric boundary, as the molecular surface (MS) or the van der Waals (vdW) surface of the solute, give very different results for the electrostatic free energy of the solute. With the same atomic radii, the solute is more solvent-exposed in the vdW specification. One way to resolve the difference is to use different sets of atomic radii for the two surfaces. The radii for the vdW surface would be larger in order to compensate for the higher solvent exposure. Here we show that radius re-parameterization required for bringing MS-based and vdW-based PB results to agreement is solute-size dependent. The difference in atomic radii for individual amino acids as solutes is only 2-5% but increases to over 20% for proteins with ~200 residues. Therefore two sets of radii that yield identical MS-based and vdW-based PB results for small solutes will give very different PB results for large solutes. This finding raises issues about two common practices. The first is the use of atomic radii, which are parameterized against either experimental solvation data or data obtained from explicit-solvent simulations on small compounds, for PB calculations on proteins. The second is the parameterization of vdW-based generalized Born models against MS-based PB results.
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Affiliation(s)
- Harianto Tjong
- Department of Physics and Institute of Molecular Biophysics and School of Computational Science Florida State University Tallahassee, FL 32306
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30
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Abstract
Docking of unbound protein structures into a complex has gained significant progress in recent years, but nonetheless still poses a great challenge. We have pursued a holistic approach to docking which brings together effective methods at different stages. First, protein-protein interaction sites are predicted or obtained from experimental studies in the literature. Interface prediction/experimental data are then used to guide the generation of docked poses or to rank docked poses generated from an unbiased search. Finally, selected models are refined by lengthy molecular dynamics (MD) simulations in explicit water. For CAPRI target T27, we used information on interaction sites as input to drive docking and as a filter to rank docked poses. Lead candidates were then clustered according to RMSD among them. From the clustering, 10 models were selected and subject to refinement by MD simulations. Our Model 7 is rated number one among all submissions according to L_rmsd. Six of our other submissions are rated acceptable. As scorer, eight of our submissions are rated acceptable.
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Affiliation(s)
- Sanbo Qin
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA
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31
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Zhou HX, Qin S, Tjong H. Modeling Protein–Protein and Protein–Nucleic Acid Interactions: Structure, Thermodynamics, and Kinetics. ANNUAL REPORTS IN COMPUTATIONAL CHEMISTRY 2008. [DOI: 10.1016/s1574-1400(08)00004-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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32
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Qin S, Zhou HX. Prediction of salt and mutational effects on the association rate of U1A protein and U1 small nuclear RNA stem/loop II. J Phys Chem B 2007; 112:5955-60. [PMID: 18154282 DOI: 10.1021/jp075919k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We have developed a computational approach for predicting protein-protein association rates (Alsallaq and Zhou, Structure 2007, 15, 215). Here we expand the range of applicability of this approach to protein-RNA binding and report the first results for protein-RNA binding rates predicted from atomistic modeling. The system studied is the U1A protein and stem/loop II of the U1 small nuclear RNA. Experimentally it was observed that the binding rate is significantly reduced by increasing salt concentration while the dissociation changes little with salt concentration, and charges distant from the binding site make marginal contribution to the binding rate. These observations are rationalized. Moreover, predicted effects of salt and charge mutations are found to be in quantitative agreement with experimental results.
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Affiliation(s)
- Sanbo Qin
- Department of Physics and Institute of Molecular Biophysics and School of Computational Science, Florida State University, Tallahassee, Florida 32306, USA
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33
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Szendroedi J, Sandtner W, Zarrabi T, Zebedin E, Hilber K, Dudley SC, Fozzard HA, Todt H. Speeding the recovery from ultraslow inactivation of voltage-gated Na+ channels by metal ion binding to the selectivity filter: a foot-on-the-door? Biophys J 2007; 93:4209-24. [PMID: 17720727 PMCID: PMC2098733 DOI: 10.1529/biophysj.107.104794] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Slow inactivated states in voltage-gated ion channels can be modulated by binding molecules both to the outside and to the inside of the pore. Thus, external K(+) inhibits C-type inactivation in Shaker K(+) channels by a "foot-in-the-door" mechanism. Here, we explore the modulation of a very long-lived inactivated state, ultraslow inactivation (I(US)), by ligand binding to the outer vestibule in voltage-gated Na(+) channels. Blocking the outer vestibule by a mutant mu-conotoxin GIIIA substantially accelerated recovery from I(US). A similar effect was observed if Cd(2+) was bound to a cysteine engineered to the selectivity filter (K1237C). In K1237C channels, exposed to 30 microM Cd(2+), the time constant of recovery from I(US) was decreased from 145.0 +/- 10.2 s to 32.5 +/- 3.3 s (P < 0.001). Recovery from I(US) was only accelerated if Cd(2+) was added to the bath solution during recovery (V = -120 mV) from I(US), but not when the channels were selectively exposed to Cd(2+) during the development of I(US) (-20 mV). These data could be explained by a kinetic model in which Cd(2+) binds with high affinity to a slow inactivated state (I(S)), which is transiently occupied during recovery from I(US). A total of 50 microM Cd(2+) produced an approximately 8 mV hyperpolarizing shift of the steady-state inactivation curve of I(S), supporting this kinetic model. Binding of lidocaine to the internal vestibule significantly reduced the number of channels entering I(US), suggesting that I(US) is associated with a conformational change of the internal vestibule of the channel. We propose a molecular model in which slow inactivation (I(S)) occurs by a closure of the outer vestibule, whereas I(US) arises from a constriction of the internal vestibule produced by a widening of the selectivity filter region. Binding of Cd(2+) to C1237 promotes the closure of the selectivity filter region, thereby hastening recovery from I(US). Thus, Cd(2+) ions may act like a foot-on-the-door, kicking the I(S) gate to close.
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Affiliation(s)
- Julia Szendroedi
- Center for Biomolecular Medicine and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
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34
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Yang W, Nymeyer H, Zhou HX, Berg B, Brüschweiler R. Quantitative computer simulations of biomolecules: A snapshot. J Comput Chem 2007; 29:668-72. [PMID: 17708535 DOI: 10.1002/jcc.20819] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A recent workshop titled "Quantitative Computational Biophysics" at Florida State University provided an overview of the state of the art in quantitative modeling of biomolecular systems. The presentations covered a wide range of interrelated topics, including the development and validation of force fields, the modeling of protein-protein interactions, the sampling of conformational space, and the assessment of equilibration and statistical errors. Substantial progress in all these areas was reported.
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Affiliation(s)
- Wei Yang
- School of Computational Science, Florida State University, Tallahassee, Florida 32306, USA
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35
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Alsallaq R, Zhou HX. Prediction of protein-protein association rates from a transition-state theory. Structure 2007; 15:215-24. [PMID: 17292839 DOI: 10.1016/j.str.2007.01.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 12/27/2006] [Accepted: 01/02/2007] [Indexed: 11/24/2022]
Abstract
We recently developed a theory for the rates of protein-protein association. The theory is based on the concept of a transition state, which separates the bound state, with numerous short-range interactions but restricted translational and rotational freedom, and the unbound state, with, at most, a small number of interactions but expanded configurational freedom. When not accompanied by large-scale conformational changes, protein-protein association becomes diffusion limited. The association rate is then predicted as k(a)=k(a)(0)exp(-DeltaG(el)(double dagger)/k(B)T), where DeltaG(el)(double dagger) is the electrostatic interaction free energy in the transition state, k(a)(0) is the rate in the absence of electrostatic interactions, and k(B)T is thermal energy. Here, this transition-state theory is used to predict the association rates of four protein complexes. The predictions for the wild-type complexes and 23 mutants are found to agree closely with experimental data over wide ranges of ionic strength.
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Affiliation(s)
- Ramzi Alsallaq
- Department of Physics and Institute of Molecular Biophysics and School of Computational Science, Florida State University, Tallahassee, FL 32306, USA
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Abstract
Formation of a stereospecific protein complex is favored by specific interactions between two proteins but disfavored by the loss of translational and rotational freedom. Echoing the protein folding process, we have previously proposed a transition state for protein-protein association. Here we clarify the specification of the transition state by working with two types of toy models for protein association. A "hemisphere" model consists of two matching hemispheres as associating proteins, and a "crater" model consists of a spherical protein with a crater to which another spherical protein fits snugly. Short-range pairwise interactions between sites across the interface hold together the bound complex. Small relative translation and rotation between the subunits quickly destroy the interactions, leading to a sharp transition between the bound state with numerous short-range interactions but restricted translation and rotational freedom and the unbound state with, at most, a small number of interactions but expanded configurational freedom. This transition sets the outer boundary of the bound state as well as the transition state for association. The energy landscape is funnel-like, with the deep well of the bound state surrounded by a broad shallow basin. Calculations with the toy models suggest that mutational change in the interaction energy in the x-ray structure of a protein-protein complex, commonly used to approximate the effect on the association constant, overestimates the effect of mutation by 10-20%. With an eye toward specifying the transition states of actual protein complexes, we find that the total number of contacts between the subunits serves as a good surrogate of the interaction energy. This formalism of protein-protein association is applied to the barnase-barstar complex, reproducing the experimental results for the association rate over a wide range of ionic strength.
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Affiliation(s)
- Ramzi Alsallaq
- Department of Physics and Institute of Molecular Biophysics and School of Computational Science, Florida State University, Tallahassee, Florida, USA
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Sumikama T, Saito S, Ohmine I. Mechanism of Ion Permeation in a Model Channel: Free Energy Surface and Dynamics of K+Ion Transport in an Anion-Doped Carbon Nanotube. J Phys Chem B 2006; 110:20671-7. [PMID: 17034258 DOI: 10.1021/jp062547r] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism of the ion permeation is investigated for an anion-doped carbon nanotube, as a model of the K+ channel, by analyzing the free energy surface and the dynamics of the ion permeation through the model channel. It is found that the main rate-determining step is how an ion enters the channel. The entrance of the ion is mostly blocked by a water molecule located at this entrance. Only about 10% of K+ ions which reach the mouth of the channel can really enter the channel. The rejection rate sensitively depends on the location of this water molecule, which is easily controlled by the charge of the carbon nanotube; for example, the maximum permeation is obtained when the anion charge is at a certain value, -5.4e in the present model. At this charge, the facile translocation of the ion inside the channel is also induced due to the number of fluctuations of the ions inside the channel. Therefore, the so-called "Newton's balls", a toy model, combined with a simple ion diffusion model for explaining the fast ion permeation should be modified. The present analysis thus suggests that there exists an optimum combination of the length and the charge of the carbon nanotube for the most efficient ion permeation.
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Affiliation(s)
- Takashi Sumikama
- Department of Chemistry, Faculty of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
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Oliveira JS, Zaharenko AJ, Ferreira WA, Konno K, Shida CS, Richardson M, Lúcio AD, Beirão PSL, de Freitas JC. BcIV, a new paralyzing peptide obtained from the venom of the sea anemone Bunodosoma caissarum. A comparison with the Na+ channel toxin BcIII. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:1592-600. [PMID: 17015047 DOI: 10.1016/j.bbapap.2006.08.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 08/22/2006] [Accepted: 08/23/2006] [Indexed: 11/24/2022]
Abstract
Sea anemones produce a wide variety of biologically active compounds, such as the proteinaceous neurotoxins and cytolysins. Herein we report a new peptide, purified to homogeneity from the neurotoxic fraction of B. caissarum venom, by using gel filtration followed by rp-HPLC, naming it as BcIV. BcIV is a 41 amino acid peptide (molecular mass of 4669 amu) possessing 6 cysteines covalently linked by three disulfide bonds. This toxin has 45 and 48% of identity when compared to APETx1 and APETx2 from Anthopleura elegantissima, respectively, and 42% of identity with Am-II and BDS-I and-II obtained from Antheopsis maculata and Anemonia sulcata, respectively. This neurotoxin presents only a weak-paralyzing action (minimal Lethal Dose close to 2000 microg/kg) in swimming crabs Callinectes danae. This appears to be a different effect to that caused by the type 1 sea anemone toxin BcIII that is lethal to the same animals at lower doses (LD50=219 microg/kg). Circular dichroism spectra of BcIII and BcIV show a high content of beta-strand secondary structure in both peptides, very similar to type 1 sodium channel toxins from various sea anemones, and to APETx1 and APETx2 from A. elegantissima, a HERG channel modulator and an ASIC3 inhibitor, respectively. Interestingly, BcIII and BcIV have similar effects on the action potential of the crab leg nerves, suggesting the same target in this tissue. As BcIII was previously reported as a Na+ channel effector and BcIV is inactive over Na+ currents of mammalian GH3 cells, we propose a species-specific action for this new molecule. A molecular model of BcIV was constructed using the structure of the APETx1 as template and putative key residues are discussed.
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Affiliation(s)
- Joacir Stolarz Oliveira
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 101, Travessa 14, 05508-900 São Paulo-SP, Brazil.
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Pimentel C, Choi SJ, Chagot B, Guette C, Camadro JM, Darbon H. Solution structure of PcFK1, a spider peptide active against Plasmodium falciparum. Protein Sci 2006; 15:628-34. [PMID: 16452619 PMCID: PMC2249782 DOI: 10.1110/ps.051860606] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Psalmopeotoxin I (PcFK1) is a 33-amino-acid residue peptide isolated from the venom of the tarantula Psalmopoeus cambridgei. It has been recently shown to possess strong antiplasmodial activity against the intra-erythrocyte stage of Plasmodium falciparum in vitro. Although the molecular target for PcFK1 is not yet determined, this peptide does not lyse erythrocytes, is not cytotoxic to nucleated mammalian cells, and does not inhibit neuromuscular function. We investigated the structural properties of PcFK1 to help understand the unique mechanism of action of this peptide and to enhance its utility as a lead compound for rational development of new antimalarial drugs. In this paper, we have determined the three-dimensional solution structure by (1)H two-dimensional NMR means of recombinant PcFK1, which is shown to belong to the ICK structural superfamily with structural determinants common to several neurotoxins acting as ion channels effectors.
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Affiliation(s)
- Cyril Pimentel
- AFMB, CNRS UMR 6098 and Universités d'Aix-Marseille I and II, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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Abstract
The I-conotoxin superfamily (I-Ctx) is known to have four disulfide bonds with the cysteine arrangement C-C-CC-CC-C-C, and the members inhibit or modify ion channels of nerve cells. Recently, Olivera and co-workers (FEBS J. 2005; 272: 4178-4188) have suggested that the previously described I-Ctx should now be divided into two different gene superfamilies, namely, I1 and I2, in view of their having two different types of signal peptides and exhibiting distinct functions. We have revisited the 28 entries presently grouped as I-Ctx in UniProt Swiss-Prot knowledgebase, and on the basis of in silico analysis have divided them into I1 and I2 superfamilies. The sequence analysis has provided a framework for in silico annotation enabling us to carry out computer-based functional characterization of the UniProtKB/TrEMBL entry Q59AA4 from Conus miles and to predict it as a member of the I2 superfamily. Furthermore, we have predicted the mature toxin of this entry and have proposed that it may be an inhibitor of voltage-gated potassium channels.
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Affiliation(s)
- Sukanta Mondal
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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