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Gasparri F, Sarkar D, Bielickaite S, Poulsen MH, Hauser AS, Pless SA. P2X2 receptor subunit interfaces are missense variant hotspots where mutations tend to increase apparent ATP affinity. Br J Pharmacol 2022; 179:3859-3874. [PMID: 35285517 PMCID: PMC9314836 DOI: 10.1111/bph.15830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 01/31/2022] [Accepted: 02/09/2022] [Indexed: 11/30/2022] Open
Abstract
Background and Purpose P2X receptors are trimeric ligand‐gated ion channels that open a cation‐selective pore in response to ATP binding to their large extracellular domain. The seven known P2X subtypes can assemble as homotrimeric or heterotrimeric complexes and contribute to numerous physiological functions, including nociception, inflammation and hearing. The overall structure of P2X receptors is well established, but little is known about the range and prevalence of human genetic variations and the functional implications of specific domains. Experimental Approach Here, we examine the impact of P2X2 receptor inter‐subunit interface missense variants identified in the human population or by structural predictions. We test both single and double mutants through electrophysiological and biochemical approaches. Key Results We demonstrate that predicted extracellular domain inter‐subunit interfaces display a higher‐than‐expected density of missense variations and that the majority of mutations that disrupt putative inter‐subunit interactions result in channels with higher apparent ATP affinity. Lastly, we show that double mutants at the subunit interface show significant energetic coupling, especially if located in close proximity. Conclusion and Implications We provide the first structural mapping of the mutational distribution across the human population in a ligand‐gated ion channel and show that the density of missense mutations is constrained between protein domains, indicating evolutionary selection at the domain level. Our data may indicate that, unlike other ligand‐gated ion channels, P2X2 receptors have evolved an intrinsically high threshold for activation, possibly to allow for additional modulation or as a cellular protection mechanism against overstimulation.
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Affiliation(s)
- Federica Gasparri
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Debayan Sarkar
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Sarune Bielickaite
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Mette Homann Poulsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Lynagh T, Flood E, Boiteux C, Sheikh ZP, Allen TW, Pless SA. Determinants of ion selectivity in ASIC1a- and ASIC2a-containing acid-sensing ion channels. J Gen Physiol 2021; 152:133617. [PMID: 31952079 PMCID: PMC7062507 DOI: 10.1085/jgp.201812297] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 12/09/2019] [Indexed: 01/10/2023] Open
Abstract
Trimeric acid-sensing ion channels (ASICs) contribute to neuronal signaling by converting extracellular acidification into excitatory sodium currents. Previous work with homomeric ASIC1a implicates conserved leucine (L7') and consecutive glycine-alanine-serine (GAS belt) residues near the middle, and conserved negatively charged (E18') residues at the bottom of the pore in ion permeation and/or selectivity. However, a conserved mechanism of ion selectivity throughout the ASIC family has not been established. We therefore explored the molecular determinants of ion selectivity in heteromeric ASIC1a/ASIC2a and homomeric ASIC2a channels using site-directed mutagenesis, electrophysiology, and molecular dynamics free energy simulations. Similar to ASIC1a, E18' residues create an energetic preference for sodium ions at the lower end of the pore in ASIC2a-containing channels. However, and in contrast to ASIC1a homomers, ion permeation through ASIC2a-containing channels is not determined by L7' side chains in the upper part of the channel. This may be, in part, due to ASIC2a-specific negatively charged residues (E59 and E62) that lower the energy of ions in the upper pore, thus making the GAS belt more important for selectivity. This is confirmed by experiments showing that the L7'A mutation has no effect in ASIC2a, in contrast to ASIC1a, where it eliminated selectivity. ASIC2a triple mutants eliminating both L7' and upper charges did not lead to large changes in selectivity, suggesting a different role for L7' in ASIC2a compared with ASIC1a channels. In contrast, we observed measurable changes in ion selectivity in ASIC2a-containing channels with GAS belt mutations. Our results suggest that ion conduction and selectivity in the upper part of the ASIC pore may differ between subtypes, whereas the essential role of E18' in ion selectivity is conserved. Furthermore, we demonstrate that heteromeric channels containing mutations in only one of two ASIC subtypes provide a means of functionally testing mutations that render homomeric channels nonfunctional.
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Affiliation(s)
- Timothy Lynagh
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Emelie Flood
- School of Science, RMIT University, Melbourne, Australia
| | - Céline Boiteux
- School of Science, RMIT University, Melbourne, Australia
| | - Zeshan Pervez Sheikh
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Toby W Allen
- School of Science, RMIT University, Melbourne, Australia
| | - Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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3
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Lynagh T, Kiontke S, Meyhoff-Madsen M, Gless BH, Johannesen J, Kattelmann S, Christiansen A, Dufva M, Laustsen AH, Devkota K, Olsen CA, Kümmel D, Pless SA, Lohse B. Peptide Inhibitors of the α-Cobratoxin-Nicotinic Acetylcholine Receptor Interaction. J Med Chem 2020; 63:13709-13718. [PMID: 33143415 PMCID: PMC7705965 DOI: 10.1021/acs.jmedchem.0c01202] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
Venomous snakebites cause >100
000 deaths every year, in many cases
via potent depression of human neuromuscular signaling by snake α-neurotoxins.
Emergency therapy still relies on antibody-based antivenom, hampered
by poor access, frequent adverse reactions, and cumbersome production/purification.
Combining high-throughput discovery and subsequent structure–function
characterization, we present simple peptides that bind α-cobratoxin
(α-Cbtx) and prevent its inhibition of nicotinic acetylcholine
receptors (nAChRs) as a lead for the development of alternative antivenoms.
Candidate peptides were identified by phage display and deep sequencing,
and hits were characterized by electrophysiological recordings, leading
to an 8-mer peptide that prevented α-Cbtx inhibition of nAChRs.
We also solved the peptide:α-Cbtx cocrystal structure, revealing
that the peptide, although of unique primary sequence, binds to α-Cbtx
by mimicking structural features of the nAChR binding pocket. This
demonstrates the potential of small peptides to neutralize lethal
snake toxins in vitro, establishing a potential route to simple, synthetic,
low-cost antivenoms.
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Affiliation(s)
- Timothy Lynagh
- Sars International Centre for Marine Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008 Bergen, Norway.,Center for Biopharmaceuticals & Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Stephan Kiontke
- Division of Structural Biology, Department of Biology/Chemistry, University of Osnabrück, Barbarastraße 13, Osnabrück 49076, Germany.,Faculty of Biology, Department of Plant Physiology and Photobiology, Philipps-Universität Marburg, Karl-von-Frisch-Straße 8, 35032 Marburg, Germany
| | - Maria Meyhoff-Madsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Bengt H Gless
- Center for Biopharmaceuticals & Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Jónas Johannesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Sabrina Kattelmann
- Institute of Biochemistry, University of Münster, Corrensstraße 36, 48149 Münster, Germany
| | - Anders Christiansen
- Fluid Array Systems and Technology, Nano and Bio-physical Systems, Department of Health Technology, Technical University of Denmark, Building 423 Produktionstorvet, DK-2800 Kongens Lyngby, Denmark
| | - Martin Dufva
- Fluid Array Systems and Technology, Nano and Bio-physical Systems, Department of Health Technology, Technical University of Denmark, Building 423 Produktionstorvet, DK-2800 Kongens Lyngby, Denmark
| | - Andreas H Laustsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Kanchan Devkota
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Christian A Olsen
- Center for Biopharmaceuticals & Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Daniel Kümmel
- Division of Structural Biology, Department of Biology/Chemistry, University of Osnabrück, Barbarastraße 13, Osnabrück 49076, Germany.,Institute of Biochemistry, University of Münster, Corrensstraße 36, 48149 Münster, Germany
| | - Stephan Alexander Pless
- Center for Biopharmaceuticals & Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Brian Lohse
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Braun N, Sheikh ZP, Pless SA. The current chemical biology tool box for studying ion channels. J Physiol 2020; 598:4455-4471. [DOI: 10.1113/jp276695] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/06/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- N. Braun
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| | - Z. P. Sheikh
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
| | - S. A. Pless
- Department of Drug Design and Pharmacology University of Copenhagen Jagtvej 160 Copenhagen 2100 Denmark
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Gasparri F, Wengel J, Grutter T, Pless SA. Molecular determinants for agonist recognition and discrimination in P2X2 receptors. J Gen Physiol 2019; 151:898-911. [PMID: 31126967 PMCID: PMC6605687 DOI: 10.1085/jgp.201912347] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/06/2019] [Indexed: 12/26/2022] Open
Abstract
P2X receptors (P2XRs) are ligand-gated cation channels involved in pain and inflammation. Gasparri et al. show that the backbone carbonyl atoms of amino acid residue Thr184 are involved in ligand discrimination, while those of Lys69 contribute mostly to ligand recognition by rat P2X2Rs. P2X receptors (P2XRs) are trimeric ligand-gated ion channels that open a cation-selective pore in response to ATP binding. P2XRs contribute to synaptic transmission and are involved in pain and inflammation, thus representing valuable drug targets. Recent crystal structures have confirmed the findings of previous studies with regards to the amino acid chains involved in ligand recognition, but they have also suggested that backbone carbonyl atoms contribute to ATP recognition and discrimination. Here we use a combination of site-directed mutagenesis, amide-to-ester substitutions, and a range of ATP analogues with subtle alterations to either base or sugar component to investigate the contributions of backbone carbonyl atoms toward ligand recognition and discrimination in rat P2X2Rs. Our findings demonstrate that while the Lys69 backbone carbonyl makes an important contribution to ligand recognition, the discrimination between different ligands is mediated by both the side chain and the backbone carbonyl oxygen of Thr184. Together, our data demonstrate how conserved elements in P2X2Rs recognize and discriminate agonists.
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Affiliation(s)
- Federica Gasparri
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Wengel
- Biomolecular Nanoscale Engineering Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Thomas Grutter
- University of Strasbourg, Centre National de la Recherche Scientifique, Conception et Application de Molécules Bioactives Unité Mixte de Recherche 7199, Strasbourg, France
| | - Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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6
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Chen MX, Wijethunge BDIK, Zhou SM, Yang JF, Dai L, Wang SS, Chen C, Fu LJ, Zhang J, Hao GF, Yang GF. Chemical Modulation of Alternative Splicing for Molecular-Target Identification by Potential Genetic Control in Agrochemical Research. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:5072-5084. [PMID: 30986354 DOI: 10.1021/acs.jafc.9b02086] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Alternative splicing (AS), the process of removing introns from pre-mRNA and the rearrangement of exons to produce several types of mature transcripts, is a remarkable step preceding protein synthesis. In particular, it has now been conclusively shown that up to ∼95% of genes are alternatively spliced to generate a complex and diverse proteome in eukaryotic organisms. Consequently, AS is one of the determinants of the functional repertoire of cells. Many studies have revealed that AS in plants can be regulated by cell type, developmental stage, environmental stress, and the circadian clock. Moreover, increasing amounts of evidence reveal that chemical compounds can affect various steps during splicing to induce major effects on plant physiology. Hence, the chemical modulation of AS can serve as a good strategy for molecular-target identification in attempts to potentially control plant genetics. However, the kind of mechanisms involved in the chemical modulation of AS that can be used in agrochemical research remain largely unknown. This review introduces recent studies describing the specific roles AS plays in plant adaptation to environmental stressors and in the regulation of development. We also discuss recent advances in small molecules that induce alterations of AS and the possibility of using this strategy in agrochemical-target identification, giving a new direction for potential genetic control in agrochemical research.
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Affiliation(s)
- Mo-Xian Chen
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering; Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education; Research and Development Center for Fine Chemicals , Guizhou University , Guiyang 550025 , PR China
- Division of Gastroenterology , Shenzhen Children's Hospital , Shenzhen 518038 , PR China
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , PR China
- School of Life Sciences and Shenzhen Research Institute , The Chinese University of Hong Kong , Shenzhen 518063 , PR China
| | - Boyagane D I K Wijethunge
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry , Central China Normal University , Wuhan 430079 , PR China
| | - Shao-Ming Zhou
- Division of Gastroenterology , Shenzhen Children's Hospital , Shenzhen 518038 , PR China
| | - Jing-Fang Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry , Central China Normal University , Wuhan 430079 , PR China
| | - Lei Dai
- Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , PR China
| | - Shan-Shan Wang
- School of Life Sciences and Shenzhen Research Institute , The Chinese University of Hong Kong , Shenzhen 518063 , PR China
| | - Chen Chen
- Department of Infectious Disease, Nanjing Second Hospital , Nanjing University of Chinese Medicine , Nanjing 210003 , PR China
| | - Li-Jun Fu
- Fujian Provincial Key Laboratory of Ecology-Toxicological Effects & Control for Emerging Contaminants , Putian University , Putian , Fujian 351100 , PR China
| | - Jianhua Zhang
- Department of Biology, Hong Kong Baptist University and State Key Laboratory of Agrobiotechnology , The Chinese University of Hong Kong , Shatin , Hong Kong , PR China
| | - Ge-Fei Hao
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering; Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education; Research and Development Center for Fine Chemicals , Guizhou University , Guiyang 550025 , PR China
| | - Guang-Fu Yang
- Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry , Central China Normal University , Wuhan 430079 , PR China
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7
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Callau-Vázquez D, Pless SA, Lynagh T. Investigation of Agonist Recognition and Channel Properties in a Flatworm Glutamate-Gated Chloride Channel. Biochemistry 2018; 57:1360-1368. [PMID: 29411605 DOI: 10.1021/acs.biochem.7b01245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Glutamate-gated chloride channels (GluCls) are neurotransmitter receptors that mediate crucial inhibitory signaling in invertebrate neuromuscular systems. Their role in invertebrate physiology and their absence from vertebrates make GluCls a prime target for antiparasitic drugs. GluCls from flatworm parasites are substantially different from and are much less understood than those from roundworm and insect parasites, hindering the development of potential therapeutics targeting GluCls in flatworm-related diseases such as schistosomiasis. Here, we sought to dissect the molecular and chemical basis for ligand recognition in the extracellular glutamate binding site of SmGluCl-2 from Schistosoma mansoni, using site-directed mutagenesis, noncanonical amino acid incorporation, and electrophysiological recordings. Our results indicate that aromatic residues in ligand binding loops A, B, and C are important for SmGluCl-2 function. Loop C, which differs in length compared to other pentameric ligand-gated ion channels (pLGICs), contributes to ligand recognition through both an aromatic residue and two vicinal threonine residues. We also show that, in contrast to other pLGICs, the hydrophobic channel gate in SmGluCl-2 extends from the 9' position to the 6' position in the channel-forming M2 helix. The 6' and 9' positions also seem to control sensitivity to the pore blocker picrotoxin.
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Affiliation(s)
- Daniel Callau-Vázquez
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - Timothy Lynagh
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
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Lynagh T, Romero-Rojo JL, Lund C, Pless SA. Molecular Basis for Allosteric Inhibition of Acid-Sensing Ion Channel 1a by Ibuprofen. J Med Chem 2017; 60:8192-8200. [PMID: 28949138 DOI: 10.1021/acs.jmedchem.7b01072] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A growing body of evidence links certain aspects of nonsteroidal anti-inflammatory drug (NSAID) pharmacology with acid-sensing ion channels (ASICs), a small family of excitatory neurotransmitter receptors implicated in pain and neuroinflammation. The molecular basis of NSAID inhibition of ASICs has remained unknown, hindering the exploration of this line of therapy. Here, we characterized the mechanism of inhibition, explored the molecular determinants of sensitivity, and sought to establish informative structure-activity relationships, using electrophysiology, site-directed mutagenesis, and voltage-clamp fluorometry. Our results show that ibuprofen is an allosteric inhibitor of ASIC1a, which binds to a crucial site in the agonist transduction pathway and causes conformational changes that oppose channel activation. Ibuprofen inhibits several ASIC subtypes, but certain ibuprofen derivatives show some selectivity for ASIC1a over ASIC2a and vice versa. These results thus define the NSAID/ASIC interaction and pave the way for small-molecule drug design targeting pain and inflammation.
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Affiliation(s)
- Timothy Lynagh
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - José Luis Romero-Rojo
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - Camilla Lund
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
| | - Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 160, 2100 Copenhagen, Denmark
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Gerecht K, Figueiredo AM, Hansen DF. Determining rotational dynamics of the guanidino group of arginine side chains in proteins by carbon-detected NMR. Chem Commun (Camb) 2017; 53:10062-10065. [PMID: 28840203 PMCID: PMC5708338 DOI: 10.1039/c7cc04821a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
A new NMR-based method is presented to determine the rotational dynamics around the Nε–Cζ bond of arginine to characterise the interactions mediated by arginine side chains.
Arginine residues are imperative for many active sites and protein-interaction interfaces. A new NMR-based method is presented to determine the rotational dynamics around the Nε–Cζ bond of arginine side chains. An application to a 19 kDa protein shows that the strengths of interactions involving arginine side chains can be characterised.
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Affiliation(s)
- Karola Gerecht
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
| | - Angelo Miguel Figueiredo
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
| | - D Flemming Hansen
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, WC1E 6BT, UK.
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