1
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Jiang L, Liu N, Zhao F, Huang B, Kang D, Zhan P, Liu X. Discovery of GluN2A subtype-selective N-methyl-d-aspartate (NMDA) receptor ligands. Acta Pharm Sin B 2024; 14:1987-2005. [PMID: 38799621 PMCID: PMC11119548 DOI: 10.1016/j.apsb.2024.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/04/2023] [Accepted: 12/28/2023] [Indexed: 05/29/2024] Open
Abstract
The N-methyl-d-aspartate (NMDA) receptors, which belong to the ionotropic Glutamate receptors, constitute a family of ligand-gated ion channels. Within the various subtypes of NMDA receptors, the GluN1/2A subtype plays a significant role in central nervous system (CNS) disorders. The present article aims to provide a comprehensive review of ligands targeting GluN2A-containing NMDA receptors, encompassing negative allosteric modulators (NAMs), positive allosteric modulators (PAMs) and competitive antagonists. Moreover, the ligands' structure-activity relationships (SARs) and the binding models of representative ligands are also discussed, providing valuable insights for the clinical rational design of effective drugs targeting CNS diseases.
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Affiliation(s)
| | | | - Fabao Zhao
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Boshi Huang
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Dongwei Kang
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Peng Zhan
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Xinyong Liu
- Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
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2
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Jimenez EC. Peptide antagonists of NMDA receptors: Structure-activity relationships for potential therapeutics. Peptides 2022; 153:170796. [PMID: 35367253 DOI: 10.1016/j.peptides.2022.170796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 03/26/2022] [Accepted: 03/27/2022] [Indexed: 12/19/2022]
Abstract
The N-methyl-D-aspartate (NMDA) receptors are heteromeric cation channels involved in memory, learning, and synaptic plasticity. The dysfunction associated with NMDA receptors results in neurodegenerative conditions. The conantokins comprise a family of Conus venom peptides that induce sleep upon intracranial injection into young mice and are known to be NMDA receptor antagonists. This work comprehensibly documents the conantokins that have been characterized to date, focusing on the biochemistry, solution structures in the presence or absence of divalent cations, functions as selective NMDA receptor antagonists, and structure-activity relationships. Furthermore, the applications of conantokins as potential therapeutics for certain neurological conditions, including neuropathic pain, epilepsy, and ischaemia that are linked to NMDA receptor dysfunction are reviewed.
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Affiliation(s)
- Elsie C Jimenez
- Department of Physical Sciences, College of Science, University of the Philippines Baguio, Baguio City 2600, Philippines.
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3
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Yuan Y, Balsara RD, Zajicek J, Kunda S, Castellino FJ. Discerning the Role of the Hydroxyproline Residue in the Structure of Conantokin Rl-B and Its Role in GluN2B Subunit-Selective Antagonistic Activity toward N-Methyl-d-Aspartate Receptors. Biochemistry 2016; 55:7112-7122. [DOI: 10.1021/acs.biochem.6b00962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Yue Yuan
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Rashna D. Balsara
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Jaroslav Zajicek
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Shailaja Kunda
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Francis J. Castellino
- W. M. Keck Center for Transgene Research and ‡Department of Chemistry
and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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4
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Vijayasarathy M, Basheer SM, Franklin JB, Balaram P. Contryphan Genes and Mature Peptides in the Venom of Nine Cone Snail Species by Transcriptomic and Mass Spectrometric Analysis. J Proteome Res 2016; 16:763-772. [DOI: 10.1021/acs.jproteome.6b00776] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | - Soorej M. Basheer
- Molecular
Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Jayaseelan Benjamin Franklin
- Andaman
and Nicobar Centre for Ocean Science and Technology, Earth System
Sciences Organisation-National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Port Blair 744103, India
| | - Padmanabhan Balaram
- Molecular
Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
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5
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Grosso C, Valentão P, Ferreres F, Andrade PB. Bioactive marine drugs and marine biomaterials for brain diseases. Mar Drugs 2014; 12:2539-89. [PMID: 24798925 PMCID: PMC4052305 DOI: 10.3390/md12052539] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/10/2014] [Accepted: 04/16/2014] [Indexed: 12/19/2022] Open
Abstract
Marine invertebrates produce a plethora of bioactive compounds, which serve as inspiration for marine biotechnology, particularly in drug discovery programs and biomaterials development. This review aims to summarize the potential of drugs derived from marine invertebrates in the field of neuroscience. Therefore, some examples of neuroprotective drugs and neurotoxins will be discussed. Their role in neuroscience research and development of new therapies targeting the central nervous system will be addressed, with particular focus on neuroinflammation and neurodegeneration. In addition, the neuronal growth promoted by marine drugs, as well as the recent advances in neural tissue engineering, will be highlighted.
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Affiliation(s)
- Clara Grosso
- REQUIMTE/Laboratory of Pharmacognosy, Department of Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, no. 228, 4050-313 Porto, Portugal.
| | - Patrícia Valentão
- REQUIMTE/Laboratory of Pharmacognosy, Department of Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, no. 228, 4050-313 Porto, Portugal.
| | - Federico Ferreres
- Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS (CSIC), P.O. Box 164, Campus University Espinardo, Murcia 30100, Spain.
| | - Paula B Andrade
- REQUIMTE/Laboratory of Pharmacognosy, Department of Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, no. 228, 4050-313 Porto, Portugal.
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6
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Platt RJ, Curtice KJ, Twede VD, Watkins M, Gruszczyński P, Bulaj G, Horvath MP, Olivera BM. From molecular phylogeny towards differentiating pharmacology for NMDA receptor subtypes. Toxicon 2014; 81:67-79. [PMID: 24508768 DOI: 10.1016/j.toxicon.2014.01.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 01/11/2014] [Accepted: 01/29/2014] [Indexed: 11/17/2022]
Abstract
In order to decode the roles that N-methyl-D-aspartate (NMDA) receptors play in excitatory neurotransmission, synaptic plasticity, and neuropathologies, there is need for ligands that differ in their subtype selectivity. The conantokin family of Conus peptides is the only group of peptidic natural products known to target NMDA receptors. Using a search that was guided by phylogeny, we identified new conantokins from the marine snail Conus bocki that complement the current repertoire of NMDA receptor pharmacology. Channel currents measured in Xenopus oocytes demonstrate conantokins conBk-A, conBk-B, and conBk-C have highest potencies for NR2D containing receptors, in contrast to previously characterized conantokins that preferentially block NR2B containing NMDA receptors. Conantokins are rich in γ-carboxyglutamate, typically 17-34 residues, and adopt helical structure in a calcium-dependent manner. As judged by CD spectroscopy, conBk-C adopts significant helical structure in a calcium ion-dependent manner, while calcium, on its own, appears insufficient to stabilize helical conformations of conBk-A or conBk-B. Molecular dynamics simulations help explain the differences in calcium-stabilized structures. Two-dimensional NMR spectroscopy shows that the 9-residue conBk-B is relatively unstructured but forms a helix in the presence of TFE and calcium ions that is similar to other conantokin structures. These newly discovered conantokins hold promise that further exploration of small peptidic antagonists will lead to a set of pharmacological tools that can be used to characterize the role of NMDA receptors in nervous system function and disease.
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Affiliation(s)
- Randall J Platt
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Kigen J Curtice
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
| | - Vernon D Twede
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Maren Watkins
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Paweł Gruszczyński
- Medicinal Chemistry, University of Utah, Salt Lake City, UT 84112, USA; Intercollegiate Faculty of Biotechnology and Chemistry, University of Gdańsk, 80-952 Gdańsk, Poland; Medical University of Gdańsk, 80-822 Gdańsk, Poland
| | - Grzegorz Bulaj
- Medicinal Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Martin P Horvath
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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7
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Sheng Z, Prorok M, Castellino FJ. Specific determinants of conantokins that dictate their selectivity for the NR2B subunit of N-methyl-D-aspartate receptors. Neuroscience 2010; 170:703-10. [PMID: 20688135 DOI: 10.1016/j.neuroscience.2010.07.056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 07/26/2010] [Accepted: 07/28/2010] [Indexed: 10/19/2022]
Abstract
Conantokins are naturally-occurring small peptide antagonists of ion flow through NMDA/glycine activated-N-methyl-d-aspartate receptor (NMDAR) ion channels. One member of the conantokin family, conantokin (con)-G, a 17-residue peptide, is selective for NMDARs containing the N-methyl-d-aspartate receptor subunit 2 B (NR2B), whereas the homologous peptides, con-T and con-R, show broader selectivity for NR2 subunits. In this study, con-G, con-R, and con-T variants were chemically synthesized and employed to investigate their subunit selectivities as inhibitors of agonist-evoked ion currents in human embryonic kidney-293 (HEK-293) cells expressing various combinations of NMDAR subunits that contain NR1a or NR1b combined with NR2A or NR2B. Using truncation and point mutants, as well as chimeric conantokins, we determined that the N-terminus of con-G contains all the determinants for NR2B selectivity. With this information, a large number of (con) variants were synthesized and used to establish minimal sequence determinants for selectivity. Tyr at position 5 broadens the NR2 selectivity, and recovery of NR2B selectivity in Tyr5 peptides was achieved by incorporating Ala or Gly at position 8. NR2B selectivity in con-R can be conferred through deletion of the Ala at position 10, thereby shifting the γ-carboxyglutamate (Gla) from position 11 to position 10, where a Gla naturally occurs in con-G and con-T. The nature of the amino acid at position 6 is also linked to subunit selectivity. Our studies suggest that the molecular determinants of conantokins that dictate NMDAR subunit selectivity are housed in specific residues of the N-termini of these peptides. Thus, it is possible to engineer desired NMDAR functional properties into conantokin-based peptides.
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Affiliation(s)
- Z Sheng
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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8
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Twede VD, Teichert RW, Walker CS, Gruszczyński P, Kaźmierkiewicz R, Bulaj G, Olivera BM. Conantokin-Br from Conus brettinghami and selectivity determinants for the NR2D subunit of the NMDA receptor. Biochemistry 2009; 48:4063-73. [PMID: 19309162 DOI: 10.1021/bi802259a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Conantokins are venom peptides from marine cone snails that are NMDA receptor antagonists. Here, we report the characterization of a 24 AA conantokin from Conus brettinghami Coomans , H. E. , Moolenbeek , R. G. and Wils , E. ( 1982 ) Basteria 46 ( 1/4 ), 3 - 67 , conantokin-Br (con-Br), the first conantokin that does not have the conserved glutamate residue at position 2. Molecular modeling studies suggest that con-Br has a helical structure between residues 2-13. In contrast to other characterized conantokins, con-Br has a high potency for NMDA receptors with NR2D subunits. To identify determinants for NR2D potency, we synthesized chimeras of con-Br and conantokin-R (con-R); the latter has a approximately 30-fold lower potency for the NR2D subtype. The characterization of two reciprocal chimeras (con-Br/R and con-R/Br), comprising the first 9-10 N-terminal AAs of each conantokin followed by the corresponding C-terminal AAs of the other conantokin demonstrates that determinants for NR2D selectivity are at the N-terminal region. Additional analogues comprising 1-3 amino acid substitutions from each peptide into the homologous region of the other led to the identification of a key determinant; a Tyr residue in position 5 increases potency for NR2D, while Val at this locus causes a decrease. The systematic definition of key determinants in the conantokin peptides for NMDA receptor subtype selectivity is an essential component in the development of conantokin peptides that are highly selective for each specific NMDA receptor subtype.
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Affiliation(s)
- Vernon D Twede
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
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9
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Bandyopadhyay PK. Vitamin K-dependent gamma-glutamylcarboxylation: an ancient posttranslational modification. VITAMINS AND HORMONES 2008; 78:157-84. [PMID: 18374194 DOI: 10.1016/s0083-6729(07)00008-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The vitamin K-dependent carboxylase carries out the posttranslational modification of specific glutamate residues in proteins to gamma-carboxy glutamic acid (Gla) in the presence of reduced vitamin K, molecular oxygen, and carbon dioxide. In the process, reduced vitamin K is converted to vitamin K epoxide, which is subsequently reduced to vitamin K, by vitamin K epoxide reductase (VKOR) for use in the carboxylation reaction. The modification has a wide range of physiological implications, including hemostasis, bone calcification, and signal transduction. The enzyme interacts with a high affinity gamma-carboxylation recognition sequence (gamma-CRS) of the substrate and carries out multiple modifications of the substrate before the product is released. This mechanism ensures complete carboxylation of the Gla domain of the coagulation factors, which is essential for their biological activity. gamma-Carboxylation, originally discovered in mammals, is widely distributed in the animal kingdom. It has been characterized in sea squirt (Ciona intestinalis), in flies (Drosophila melanogaster), and in marine snails (Conus textile), none of which have a blood coagulation system similar to mammals. The cone snails express a large array of gamma-carboxylated peptides that modulate the activity of ion channels. These findings have led to the suggestion that gamma-carboxylation is an extracellular posttranslational modification that antedates the divergence of molluscs, arthropods, and chordates. I will first summarize recent understanding of gamma-carboxylase and gamma-carboxylation gleaned from experiments using the mammalian enzyme, and then I will briefly describe the available information on gamma-carboxylation in D. melanogaster and C. textile.
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Affiliation(s)
- Pradip K Bandyopadhyay
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112, USA
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Moon S, Case DA. A comparison of quantum chemical models for calculating NMR shielding parameters in peptides: mixed basis set and ONIOM methods combined with a complete basis set extrapolation. J Comput Chem 2007; 27:825-36. [PMID: 16541428 DOI: 10.1002/jcc.20388] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This article compares several quantum mechanical approaches to the computation of chemical shielding tensors in peptide fragments. First, we describe the effects of basis set quality up to the complete basis set (CBS) limit and level of theory (HF, MP2, and DFT) for four different atoms in trans N-methylacetamide. For both isotropic shielding and shielding anisotropy, the MP2 results in the CBS limit show the best agreement with experiment. The HF values show quite a different tendency to MP2, and even in the CBS limit they are far from experiment for not only the isotropic shielding of carbonyl carbon but also most shielding anisotropies. In most cases, the DFT values differ systematically from MP2, and small basis-set (double- or triple-zeta) results are often fortuitously in better agreement with the experiment than the CBS ones. Second, we compare the mixed basis set and ONIOM methods, combined with CBS extrapolation, for chemical shielding calculations at a DFT level using various model peptides. From the results, it is shown that the mixed basis set method provides better results than ONIOM, compared to CBS calculations using the nonpartitioned full systems. The information studied here will be useful in guiding the selection of proper quantum chemical models, which are in a tradeoff between accuracy and cost, for shielding studies of peptides and proteins.
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Affiliation(s)
- Seongho Moon
- Department of Molecular Biology, Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, California 92037
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Sheng Z, Dai Q, Prorok M, Castellino FJ. Subtype-selective antagonism of N-methyl-D-aspartate receptor ion channels by synthetic conantokin peptides. Neuropharmacology 2007; 53:145-56. [PMID: 17588620 PMCID: PMC3965200 DOI: 10.1016/j.neuropharm.2007.04.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 03/28/2007] [Accepted: 04/25/2007] [Indexed: 01/29/2023]
Abstract
Conantokin-G (con-G), conantokin-T (con-T), a truncated conantokin-R (con-R[1-17]), that functions the same as wild-type con-R, and variant sequences of con-T, were chemically synthesized and employed to investigate their selectivities as antagonists of glutamate/glycine-evoked ion currents in human embryonic kidney-293 cells expressing various combinations of NMDA receptor (NMDAR) subunits (NR), viz., NR1a/2A, NR1a/2B, NR1b/2A and NR1b/2B. Con-G did not substantially affect ion flow into NR1a,b/NR2A-transfected cells, but potently inhibited cells expressing NR1a,b/NR2B, showing high NR2B selectivity. Con-T and con-R served as non-selective antagonists of all of four NMDAR subunit combinations. C-terminal truncation variants of the 21-residue con-T were synthesized and examined in this regard. While NMDAR ion channel antagonist activity, and the ability to adopt the Ca(2+)-induced alpha-helical conformation, diminished as a function of shortening the COOH-terminus of con-T, NMDAR subtype selectivity was enhanced in the con-T[1-11], con-T[1-9], and con-T[1-8] variants toward NR2A, NR1b, and NR1b/2A, respectively. Receptor subtype selectivity was also obtained with Met-8 sequence variants of con-T. Con-T[M8A] and con-T[M8Q] displayed selectivity with NR2B-containing subunits, while con-T[M8E] showed enhanced activity toward NR1b-containing NMDAR subtypes. Of those studied, the most highly selective variant was con-T[M8I], which showed maximal NMDAR ion channel antagonism activity toward the NR1a/2A subtype. These studies demonstrate that it is possible to engineer NMDAR subtype antagonist specificity into con-T. Since the subunit composition of the NMDAR varies temporally and spatially in developing brain and in various disease states, conantokins with high subtype selectivities are potentially valuable drugs that may be used at specific stages of disease and in selected regions of the brain.
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Affiliation(s)
- Zhenyu Sheng
- W.M. Keck Center for Transgene Research, 230 Raclin-Carmichael Hall, University of Notre Dame, Notre Dame, IN 46556, USA
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Hansson K, Thämlitz AM, Furie B, Furie BC, Stenflo J. A single gamma-carboxyglutamic acid residue in a novel cysteine-rich secretory protein without propeptide. Biochemistry 2006; 45:12828-39. [PMID: 17042501 DOI: 10.1021/bi061311a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gamma-glutamyl carboxylase catalyzes the modification of specific glutamyl residues to gamma-carboxyglutamyl (Gla) residues in precursor proteins that possess the appropriate gamma-carboxylation recognition signal within the propeptide region. We describe the immunopurification and first biochemical characterization of an invertebrate high molecular weight Gla-containing protein with homologues in mammals. The protein, named GlaCrisp, was isolated from the venom of the marine cone snail Conus marmoreus. GlaCrisp gave intense signals in Western blot experiments employing the Gla-specific antibody M3B, and the presence of Gla was chemically confirmed by amino acid analysis after alkaline hydrolysis. Characterization of a full-length cDNA clone encoding GlaCrisp deduced a precursor containing an N-terminal signal peptide but, unlike other Gla-containing proteins, no apparent propeptide. The predicted mature protein of 265 amino acid residues showed considerable sequence similarity to the widely distributed cysteine-rich secretory protein family and closest similarity (65% identity) to the recently described substrate-specific protease Tex31. In addition, two cDNA clones encoding the precursors of two isoforms of GlaCrisp were identified. The predicted precursor isoforms differed at three amino acid positions (-6, 9, and 25). Analysis by Edman degradation and nanoelectrospray ionization mass spectrometry, before and after methyl esterfication, identified a Gla residue at amino acid position 9 in GlaCrisp. This is the first example of a Gla-containing protein without an obvious gamma-carboxylation recognition site. The results define a new class of Gla proteins and support the notion that gamma-carboxylation of glutamyl residues is phylogenetically older than blood coagulation and the vertebrate lineage.
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Affiliation(s)
- Karin Hansson
- Department of Clinical Chemistry, Lund University, University Hospital, Malmö, S-20502 Malmö, Sweden.
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Hudáky P, Perczel A. Toward direct determination of conformations of protein building units from multidimensional NMR experiments VI. Chemical shift analysis of his to gain 3D structure and protonation state information. J Comput Chem 2005; 26:1307-17. [PMID: 15999335 DOI: 10.1002/jcc.20266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
NMR--chemical shift structure correlations were investigated by using GIAO-RB3LYP/6-311++G(2d,2p) formalism. Geometries and chemical shifts (CSI values) of 103 different conformers of N'-formyl-L-histidinamide were determined including both neutral and charged protonation forms. Correlations between amino acid torsional angle values and chemical shifts were investigated for the first time for an aromatic and polar amino acid residue whose side chain may carry different charges. Linear correlation coefficients of a significant level were determined between chemical shifts and dihedral angles for CSI[(1)H(alpha)]/phi, CSI[(13)C(alpha)]/phi, and CSI[(13)C(alpha)]/psi. Protonation of the imidazole ring induces the upfield shift of CSI[(13)C(alpha)] for positively charged histidines and an opposite effect for the negative residue. We investigated the correspondence of theoretical and experimental (13)C(alpha), (13)C(beta), and (1)H(alpha) chemical shifts and the nine basic conformational building units characteristic for proteins. These three chemical shift values allow the identification of conformational building units at 80% accuracy. These results enable the prediction of additional regular secondary structural elements (e.g., polyProlineII, inverse gamma-turns) and loops beyond the assignment of chemical shifts to alpha-helices and beta-pleated sheets. Moreover, the location of the His residue can be further specified in a beta-sheet. It is possible to determine whether the appropriate residue is located at the middle or in a first/last beta-strand within a beta-sheet based on calculated CSI values. Thus, the attractive idea of establishing local residue specific backbone folding parameters in peptides and proteins by employing chemical shift information (e.g., (1)H(alpha) and (13)C(alpha)) obtained from selected heteronuclear correlation NMR experiments (e.g., 2D-HSQC) is reinforced.
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Affiliation(s)
- Péter Hudáky
- Department of Theoretical Chemistry; Eötvös University, Budapest 112, P.O. Box 32, H-1518, Hungary
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Rishavy MA, Hallgren KW, Yakubenko AV, Zuerner RL, Runge KW, Berkner KL. The vitamin K-dependent carboxylase has been acquired by Leptospira pathogens and shows altered activity that suggests a role other than protein carboxylation. J Biol Chem 2005; 280:34870-7. [PMID: 16061481 DOI: 10.1074/jbc.m504345200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leptospirosis is an emerging infectious disease whose pathology includes a hemorrhagic response, and sequencing of the Leptospira interrogans genome revealed an ortholog of the vitamin K-dependent (VKD) carboxylase as one of several hemostatic proteins present in the bacterium. Until now, the VKD carboxylase was known to be present only in the animal kingdom (i.e. metazoans that include mammals, fish, snails, and insects), and this restricted distribution and high sequence similarity between metazoan and Leptospira orthologs strongly suggests that Leptospira acquired the VKD carboxylase by horizontal gene transfer. In metazoans, the VKD carboxylase is bifunctional, acting as an epoxidase that oxygenates vitamin K to a strong base and a carboxylase that uses the base to carboxylate Glu residues in VKD proteins, rendering them active in hemostasis and other physiologies. In contrast, the Leptospira ortholog showed epoxidase but not detectable carboxylase activity and divergence in a region of identity in all known metazoan VKD carboxylases that is important to Glu interaction. Furthermore, although the mammalian carboxylase is regulated so that vitamin K epoxidation does not occur unless Glu substrate is present, the Leptospira VKD epoxidase showed unfettered epoxidation in the absence of Glu substrate. Finally, human VKD protein orthologs were not detected in the L. interrogans genome. The combined data, then, suggest that Leptospira exapted the metazoan VKD carboxylase for some use other than VKD protein carboxylation, such as using the strong vitamin K base to drive a new reaction or to promote oxidative damage or depleting vitamin K to indirectly inhibit host VKD protein carboxylation.
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Affiliation(s)
- Mark A Rishavy
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, Ohio 44195, USA
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15
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Hansson K, Ma X, Eliasson L, Czerwiec E, Furie B, Furie BC, Rorsman P, Stenflo J. The First γ-Carboxyglutamic Acid-containing Contryphan. J Biol Chem 2004; 279:32453-63. [PMID: 15155730 DOI: 10.1074/jbc.m313825200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Contryphans constitute a group of conopeptides that are known to contain an unusual density of post-translational modifications including tryptophan bromination, amidation of the C-terminal residue, leucine, and tryptophan isomerization, and proline hydroxylation. Here we report the identification and characterization of a new member of this family, glacontryphan-M from the venom of Conus marmoreus. This is the first known example of a contryphan peptide carrying glutamyl residues that have been post-translationally carboxylated to gamma-carboxyglutamyl (Gla) residues. The amino acid sequence of glacontryphan-M was determined using automated Edman degradation and electrospray ionization mass spectrometry. The amino acid sequence of the peptide is: Asn-Gla-Ser-Gla-Cys-Pro-D-Trp-His-Pro-Trp-Cys. As with most other contryphans, glacontryphan-M is amidated at the C terminus and maintains the five-residue intercysteine loop. The occurrence of a D-tryptophan residue was confirmed by chemical synthesis and HPLC elution profiles. Using fluorescence spectroscopy we demonstrated that the Gla-containing peptide binds calcium with a K(D) of 0.63 mM. Cloning of the full-length cDNA encoding glacontryphan-M revealed that the primary translation product carries an N-terminal signal/propeptide sequence that is homologous to earlier reported contryphan signal/propeptide sequences up to 10 amino acids preceding the toxin region. Electrophysiological experiments, carried out on mouse pancreatic B-cells, showed that glacontryphan-M blocks L-type voltage-gated calcium ion channel activity in a calcium-dependent manner. Glacontryphan-M is the first contryphan reported to modulate the activity of L-type calcium ion channels.
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MESH Headings
- 1-Carboxyglutamic Acid/metabolism
- Amino Acid Sequence
- Animals
- Base Sequence
- Calcium/chemistry
- Calcium/metabolism
- Calcium Channels/metabolism
- Cations
- Chromatography, High Pressure Liquid
- DNA, Complementary/metabolism
- Disulfides
- Dose-Response Relationship, Drug
- Electrophysiology
- Hydrolysis
- Ions
- Kinetics
- Molecular Sequence Data
- Mollusk Venoms/chemistry
- Mollusk Venoms/metabolism
- Peptide Biosynthesis
- Peptides/chemistry
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/metabolism
- Protein Binding
- Protein Processing, Post-Translational
- Protein Structure, Tertiary
- Sequence Homology, Amino Acid
- Snails
- Spectrometry, Fluorescence
- Spectrometry, Mass, Electrospray Ionization
- Time Factors
- Tryptophan/chemistry
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Affiliation(s)
- Karin Hansson
- Department of Clinical Chemistry, Lund University, University Hospital, Malmö, S-205 02 Malmo, Sweden.
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16
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Dai Q, Prorok M, Castellino FJ. A New Mechanism for Metal Ion-assisted Interchain Helix Assembly in a Naturally Occurring Peptide Mediated by Optimally Spaced γ-Carboxyglutamic Acid Residues. J Mol Biol 2004; 336:731-44. [PMID: 15095984 DOI: 10.1016/j.jmb.2003.12.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Accepted: 12/08/2003] [Indexed: 11/17/2022]
Abstract
Helix-helix interactions, such as those that occur in coiled-coil domains, four-helix bundles, or membrane-spanning helical bundles, are important to the structural organization and function of numerous proteins. However, tractable peptide models for studying such structural elements have been limited to synthetic analogs of coiled-coil protein domains and de novo designed peptides. The present study provides evidence that conantokin-G (con-G), a gamma-carboxyglutamate (Gla)-rich neuroactive peptide from a venomous marine snail, can self-associate in the presence of certain divalent metal cations. Sedimentation equilibrium analyses of con-G show that Ca2+ binding promotes peptide dimerization, while the addition of the tighter binding divalent cations, Mg2+, Zn2+, and Mn2+, does not result in intermolecular association. The effects of specific residue replacements indicate that an i, i + 4, i + 7, i + 11 arrangement of Gla residues is essential for con-G self-assembly. To determine the relative chain orientation of the dimeric assembly, distributions of Cys-containing con-G variants were examined in thiol-disulfide rearrangement assays and the results were consistent with an antiparallel alignment. Our data suggest that the driving force for con-G dimerization stems from the appropriate balance of interchain and intrachain metal ion coordination by Gla residues in similar locations. These findings suggest a new role for Gla residues and accompanying cation binding in the stabilization of interstrand helix association in a natural product and provide a model for controlled assembly of peptide chains or segments of larger proteins.
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Affiliation(s)
- Qiuyun Dai
- Department of Chemistry and Biochemistry and the W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA
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17
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Perczel A, Füzéry AK, Császár AG. Toward direct determination of conformations of protein building units from multidimensional NMR experiments. V. NMR chemical shielding analysis of N-formyl-serinamide, a model for polar side-chain containing peptides. J Comput Chem 2003; 24:1157-71. [PMID: 12820123 DOI: 10.1002/jcc.10286] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Knowledge of chemical shift-structure relationships could greatly facilitate the NMR chemical shift assignment and structure refinement processes that occur during peptide/protein structure determination via NMR spectroscopy. To determine whether such correlations exist for polar side chain containing amino acid residues the serine dipeptide model, For-L-Ser-NH(2), was studied. Using the GIAO-RHF/6-31+G(d) and GIAO-RHF/TZ2P levels of theory the NMR chemical shifts of all hydrogen ((1)H(N), (1)H(alpha), (1)H(beta1), (1)H(beta2)), carbon ((13)C(alpha), (13)C(beta), (13)C') and nitrogen ((15)N) atoms have been computed for all 44 stable conformers of For-L-Ser-NH(2). An attempt was made to establish correlation between chemical shift of each nucleus and the major conformational variables (omega(0), phi, psi, omega(1), chi,(1) and chi(2)). At both levels of theory a linear correlation can be observed between (1)H(alpha)/phi, (13)C(alpha)/phi, and (13)C(alpha)/psi. These results indicate that the backbone and side-chain structures of For-L-Ser-NH(2) have a strong influence on its chemical shifts.
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Affiliation(s)
- András Perczel
- Department of Organic Chemistry, Eötvös University, Budapest 112, P.O. Box 32, H-1518, Hungary.
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18
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Klein RC, Prorok M, Castellino FJ. Direct binding properties of conantokins to native N-methyl-d-aspartate receptors. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 61:307-17. [PMID: 12753378 DOI: 10.1034/j.1399-3011.2003.00059.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Conantokin-G (con-G) is a small, gamma-carboxyglutamic acid (Gla)-containing peptide that functions neurophysiologically by inhibiting the N-methyl-d-aspartate receptor (NMDAR). In the current study, the receptor binding properties of an alanine-rich, Gla-deficient con-G variant, Ala-con-G, were assessed following tracer radioiodination with 125I. Direct binding experiments with [125I]Ala-con-G yielded a single site defined by a Kd value of 516 +/- 120 nm. Displacement of [125I]Ala-con-G binding by Ala-con-G resulted in 100% displacement with an IC50 value of 564 +/- 33 nm, while heterologous displacement by con-G[S16Y], con-G, con-T, and con-R[1-17] yielded IC50 values in the range of 15-45 microm. No displacement was observed with d-gamma-con-G or con-G[L5A], analogs that are inactive at NMDARs. Specific [125I]Ala-con-G binding was displaced by NMDA and 2-amino-5-phosphopentanoic acid in a dose-dependent manner, suggesting an interaction at the glutamate binding site. The direct binding of [125I]Ala-con-G to adult rat brain sections revealed an anatomical distribution of binding sites in all regions known to contain the NR2B subunit of the NMDAR. These results constitute the only known demonstration of the direct binding of a radiolabeled conantokin to the NMDARs present in rat brain membrane preparations and rat brain sections, and suggest that radiolabeled Ala-con-G, and similar conantokin derivatives, may find utility as probes of NMDARs in a variety of systems.
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Affiliation(s)
- R C Klein
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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19
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Czerwiec E, Begley GS, Bronstein M, Stenflo J, Taylor K, Furie BC, Furie B. Expression and characterization of recombinant vitamin K-dependent gamma-glutamyl carboxylase from an invertebrate, Conus textile. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:6162-72. [PMID: 12473112 DOI: 10.1046/j.1432-1033.2002.03335.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The marine snail Conus is the sole invertebrate wherein both the vitamin K-dependent carboxylase and its product, gamma-carboxyglutamic acid, have been identified. To examine its biosynthesis of gamma-carboxyglutamic acid, we studied the carboxylase from Conus venom ducts. The carboxylase cDNA from Conus textile has an ORF that encodes a 811-amino-acid protein which exhibits sequence similarity to the vertebrate carboxylases, with 41% identity and approximately 60% sequence similarity to the bovine carboxylase. Expression of this cDNA in COS cells or insect cells yielded vitamin K-dependent carboxylase activity and vitamin K-dependent epoxidase activity. The recombinant carboxylase has a molecular mass of approximately 130 kDa. The recombinant Conus carboxylase carboxylated Phe-Leu-Glu-Glu-Leu and the 28-residue peptides based on residues -18 to +10 of human proprothrombin and proFactor IX with Km values of 420 micro m, 1.7 micro m and 6 micro m, respectively; the Km for vitamin K is 52 micro m. The Km values for peptides based on the sequence of the conotoxin epsilon-TxIX and two precursor analogs containing 12 or 29 amino acids of the propeptide region are 565 micro m, 75 micro m and 74 micro m, respectively. The recombinant Conus carboxylase, in the absence of endogenous substrates, is stimulated up to fivefold by vertebrate propeptides but not by Conus propeptides. These results suggest two propeptide-binding sites in the carboxylase, one that binds the Conus and vertebrate propeptides and is required for substrate binding, and the other that binds only the vertebrate propeptide and is required for enzyme stimulation. The marked functional and structural similarities between the Conus carboxylase and vertebrate vitamin K-dependent gamma-carboxylases argue for conservation of a vitamin K-dependent carboxylase across animal species and the importance of gamma-carboxyglutamic acid synthesis in diverse biological systems.
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Affiliation(s)
- Eva Czerwiec
- Marine Biological Laboratory, Woods Hole, MA, USA
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20
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Klein RC, Prorok M, Galdzicki Z, Castellino FJ. The amino acid residue at sequence position 5 in the conantokin peptides partially governs subunit-selective antagonism of recombinant N-methyl-D-aspartate receptors. J Biol Chem 2001; 276:26860-7. [PMID: 11335724 DOI: 10.1074/jbc.m102428200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Whole cell voltage clamp recordings were performed to assess the ability of conantokin-G (con-G), conantokin-T (con-T), and a 17-residue truncated form of conantokin-R (con-R[1-17]) to inhibit N-methyl-d-aspartate (NMDA)-evoked currents in human embryonic kidney 293 cells transiently expressing various combinations of NR1a, NR1b, NR2A, and NR2B receptor subunits. Con-T and con-R[1-17] attenuated ion currents in cells expressing NR1a/NR2A or NR1a/NR2B. Con-G did not affect NMDA-evoked ionic currents in cells expressing NR1a/NR2A, but it showed inhibitory activity in cells expressing NR1a/NR2B receptors and the triheteromeric combination of NR1a/NR2A/NR2B. An Ala-rich con-G analog, con-G[Q6G/gamma7K/N8A/gamma10A/gamma14A/K15A/S16A/N17A] (Ala/con-G, where gamma is Gla), in which all nonessential amino acids were altered to Ala residues, manifested subunit specificity similar to that of con-G, suggesting that the replaced residues are not responsible for selectivity in the con-G framework. A sarcosine-containing con-T truncation analog, con-T[1-9/G1Src/Q6G], inhibited currents in NR1a/NR2A and NR1a/NR2B receptors, eliminating residues 10-21 as mediators of the broad subunit selectivity of con-T. In contrast to the null effects of con-G and Ala/con-G at a NR1a/NR2A-containing receptor, some inhibition ( approximately 40%) of NMDA-evoked currents was effected by these peptides in cells expressing NR1b/NR2A. This finding suggests that the presence of exon 5 in NR1b plays a role in the activity of the conantokins. Analysis of various conantokin analogs demonstrated that Leu(5) of con-G is an important determinant of conantokin selectivity. Taken as a whole, these results suggest that the important molecular determinants on conantokins responsible for NMDA receptor activity and specificity are discretely housed in specific residues of these peptides, thus allowing molecular manipulation of the NMDA receptor inhibitory properties of the conantokins.
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Affiliation(s)
- R C Klein
- Department of Chemistry and Biochemistry and the W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana 46556, USA
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21
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Blandl T, Zajicek J, Prorok M, Castellino FJ. Sequence requirements for the N-methyl-D-aspartate receptor antagonist activity of conantokin-R. J Biol Chem 2001; 276:7391-6. [PMID: 11096077 DOI: 10.1074/jbc.m006648200] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Conantokin-R (con-R), a gamma-carboxyglutamate-containing 27-residue peptide, is a natural peptide inhibitor of the N-methyl-d-aspartate (NMDA) subtype glutamate receptor. Synthetic analogs of con-R were generated to evaluate the importance of the individual structural elements of this peptide in its NMDA receptor antagonist activity, measured by inhibition of the spermine-enhanced binding of the NMDA receptor-specific channel blocker, [(3)H]MK-801, to rat brain membranes. Progressive C-terminal truncations of the 27-residue peptide revealed stages of severe activity loss. These occurred at con-R[1-11] and con-R[1-7], corresponding to the deletions of Leu(12)-Pro(27) and Met(8)-Pro(27) respectively. A second set of analogs featured single Ala substitutions in the fully active con-R[1-17] fragment. The replacement of Met(8) and Leu(12) by Ala resulted in approximate 20- and 55-fold decreases of inhibitor potency, respectively. In addition to these two residues, the only other positions where a single Ala substitution led to substantial losses (from 11-fold to >1000-fold) of activity were those of the first five N-terminal amino acids. Based on the above findings, the binding epitope of con-R was localized to the N-terminal turn of the helix and other residues on one face along two subsequent turns. This contribution pattern of the side chains in activity closely resembles the results obtained with another member of this peptide family, conantokin-T. The secondary structure and metal ion binding properties of the con-R variants were also evaluated using circular dichroism spectroscopy. Divalent cation-dependent increases of alpha-helix content were observed in most analogs. However, analogs with replacement of Gla(11) and Gla(15), as well as truncation fragments shorter than 15 residues, lost the ability to be stabilized by metal ions. These results confirmed the location of the primary divalent cation binding locus at Gla(11) and Gla(15). Additional interactions were indicated by the reduced alpha-helix stability in the Ala analogs of Gla(4), Lys(7), and Arg(14).
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Affiliation(s)
- T Blandl
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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