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Li Z, Cong Y, Wu T, Wang T, Lou X, Yang X, Yan N. Structural basis for different ω-agatoxin IVA sensitivities of the P-type and Q-type Ca v2.1 channels. Cell Res 2024; 34:455-457. [PMID: 38443561 PMCID: PMC11143261 DOI: 10.1038/s41422-024-00940-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/14/2024] [Indexed: 03/07/2024] Open
Affiliation(s)
- Zhangqiang Li
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
| | - Ye Cong
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Tong Wu
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Tongtong Wang
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xinyao Lou
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xinyu Yang
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Nieng Yan
- Beijing Frontier Research Center for Biological Structures, State Key Laboratory of Membrane Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
- Institute of Bio-Architecture and Bio-Interactions, Shenzhen Medical Academy of Research and Translation, Shenzhen, Guangdong, China.
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2
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Arranz-Tagarro JA, de los Ríos C, García AG, Padín JF. Recent patents on calcium channel blockers: emphasis on CNS diseases. Expert Opin Ther Pat 2014; 24:959-77. [DOI: 10.1517/13543776.2014.940892] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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3
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Bingham JP, Andrews EA, Kiyabu SM, Cabalteja CC. Drugs from slugs. Part II--conopeptide bioengineering. Chem Biol Interact 2012; 200:92-113. [PMID: 23063744 DOI: 10.1016/j.cbi.2012.09.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 08/27/2012] [Accepted: 09/17/2012] [Indexed: 11/27/2022]
Abstract
The biological transformation of toxins as research probes, or as pharmaceutical drug leads, is an onerous and drawn out process. Issues regarding changes to pharmacological specificity, desired potency, and bioavailability are compounded naturally by their inherent toxicity. These often scuttle their progress as they move up the narrowing drug development pipeline. Yet one class of peptide toxins, from the genus Conus, has in many ways spearheaded the expansion of new peptide bioengineering techniques to aid peptide toxin pharmaceutical development. What has now emerged is the sequential bioengineering of new research probes and drug leads that owe their lineage to these highly potent and isoform specific peptides. Here we discuss the progressive bioengineering steps that many conopeptides have transitioned through, and specifically illustrate some of the biochemical approaches that have been established to maximize their biological research potential and pharmaceutical worth.
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Affiliation(s)
- Jon-Paul Bingham
- Department of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI 96822, USA.
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4
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Norton RS. Structure and Function of Peptide and Protein Toxins from Marine Organisms. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/15569549809009246] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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5
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6
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Bernard C, Corzo G, Adachi-Akahane S, Foures G, Kanemaru K, Furukawa Y, Nakajima T, Darbon H. Solution structure of ADO1, a toxin extracted from the saliva of the assassin bug, Agriosphodrus dohrni. Proteins 2004; 54:195-205. [PMID: 14696181 DOI: 10.1002/prot.10513] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
ADO1 is a toxin purified from the saliva of the assassin bug, Agriosphodrus dohrni. Because of its similarity in sequence to Ptu1 from another assassin bug, we did not assess its pharmacologic target. Here, we demonstrate by electrophysiologic means that ADO1 targets the P/Q-type voltage-sensitive calcium channel. We also determine the solution structure of ADO1 using two-dimensional NMR techniques, followed by distance geometry and molecular dynamics. The structure of ADO1 belongs to the inhibitory cystine knot (ICK) structural family (i.e., a compact disulfide-bonded core from which four loops emerge). ADO1 contains a two-stranded, antiparallel beta-sheet structure. We compare the structure of ADO1 with other voltage-sensitive calcium-channel blockers, analyze the topologic juxtaposition of key functional residues, and conclude that the recognition of voltage-sensitive calcium channels by toxins belonging to the ICK structural family requires residues located on two distinct areas of the molecular surface of the toxins.
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Affiliation(s)
- Cédric Bernard
- Architecture et Fonction des Macromolécules Biologiques, UMR 6098, CNRS and Universités d'Aix-Marseille I and II, Marseille, France
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7
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Yan Y, Tu G, Luo X, Dai Q, Huang P, Zhang R. Three-dimensional solution structure of ω-conotoxin SO3 determined by1H NMR. ACTA ACUST UNITED AC 2003. [DOI: 10.1007/bf03185760] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Goldenberg DP, Koehn RE, Gilbert DE, Wagner G. Solution structure and backbone dynamics of an omega-conotoxin precursor. Protein Sci 2001; 10:538-50. [PMID: 11344322 PMCID: PMC2374133 DOI: 10.1110/ps.30701] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Nuclear magnetic resonance spectroscopy was used to characterize the solution structure and backbone dynamics of a putative precursor form of omega-conotoxin MVIIA, a 25-amino-acid residue peptide antagonist of voltage-gated Ca(2+) channels. The mature peptide is found in the venom of a fish-hunting marine snail Conus magus and contains an amidated carboxyl terminus that is generated by oxidative cleavage of a Gly residue. The form examined in this study is identical to the mature peptide except for the presence of the unmodified carboxy-terminal Gly. This form, referred to as omega-MVIIA-Gly, has previously been shown to refold and form its disulfides more efficiently than the mature form, suggesting that the presence of the terminal Gly may favor folding in vivo. The nuclear magnetic resonance (NMR) structure determination indicated that the fold of omega-MVIIA-Gly is very similar to that previously determined for the mature form, but revealed that the terminal Gly residue participates in a network of hydrogen bonds involving both backbone and side chain atoms, very likely accounting for the enhanced stability and folding efficiency. (15)N relaxation experiments indicated that the backbone is well ordered on the nanosecond time scale but that residues 9-15 undergo a conformational exchange processes with a time constant of approximately 35 microseconds. Other studies have implicated this segment in the binding of the peptide to its physiological target, and the observed motions may play a role in allowing the peptide to enter the binding site
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Affiliation(s)
- D P Goldenberg
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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9
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Sato K, Raymond C, Martin-Moutot N, Sasaki T, Ohtake A, Minami K, Van Renterghem C, Kim JI, Takahashi M, Seagar MJ. Binding of Ala-scanning analogs of omega-conotoxin MVIIC to N- and P/Q-type calcium channels. FEBS Lett 2000; 469:147-50. [PMID: 10713260 DOI: 10.1016/s0014-5793(00)01263-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
omega-Conotoxin MVIIC binds to P/Q-type calcium channels with high affinity and N-type channels with low affinity. To reveal the residues essential for subtype selectivity, we synthesized Ala-scanning analogs of MVIIC. Binding assays using rat cerebellar P(2) membranes suggested that Thr(11), Tyr(13) and Lys(2) are essential for binding to both N- and P/Q-type channels, whereas Lys(4) and Arg(22) are important for binding to P/Q-type channels. These results suggest that MVIIC interacts with P/Q-type channels via a large surface, in good agreement with previous observations using chimeric analogs.
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Affiliation(s)
- K Sato
- Mitsubishi Kasei Institute of Life Sciences, 11 Minamiooya, Machida, Tokyo, Japan.
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10
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Sato K, Raymond C, Martin-Moutot N, Sasaki T, Ohtake A, Minami K, Van Renterghem C, Takahashi M, Seagar MJ. Binding of six chimeric analogs of omega-conotoxin MVIIA and MVIIC to N- and P/Q-type calcium channels. Biochem Biophys Res Commun 2000; 269:254-6. [PMID: 10694509 DOI: 10.1006/bbrc.2000.2284] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Replacement of the N-terminal half of omega-conotoxin MVIIC, a peptide blocker of P/Q-type calcium channels, with that of omega-conotoxin MVIIA significantly increased the affinity for N-type calcium channels. To identify the residues essential for subtype selectivity, we examined single reverse mutations from MVIIA-type to MVIIC-type in this chimeric analog. A reverse mutation from Lys(7) to Pro(7) decreased the affinity for both P/Q- and N-type channels, whereas that from Leu(11) to Thr(11) increased the affinity for P/Q-type channels and decreased the affinity for N-type channels. The roles of these two residues were confirmed by synthesizing two MVIIC analogs in which Pro(7) and Thr(11) were replaced with Lys(7) and Leu(11), respectively.
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Affiliation(s)
- K Sato
- Mitsubishi Kasei Institute of Life Sciences, 11 Minamiooya, Machida, Tokyo, 194-8511, Japan.
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11
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Abstract
Due to their selectivity towards voltage-sensitive calcium channels (VSCCs) omega-conotoxins are being exploited as a new class of therapeutics in pain management and may also have potential application in ischaemic brain injury. Here, the structure-activity relationships (SARs) of several omega-conotoxins including GVIA, MVIIA, CVID and MVIIC are explored. In addition, the three-dimensional structures of these omega-conotoxins and some structurally related peptides that form the cysteine knot are compared, and the effects of the solution environment on structure discussed. The diversity of binding and functional assays used to measure omega-conotoxin potencies at the N-type VSCC warranted a re-evaluation of the relationship between these assays. With one exception, [A22]-GVIA, this analysis revealed a linear correlation between functional (peripheral N-type VSCCs) and radioligand binding assays (central N-type VSCCs) for the omega-conotoxins and analogues that were tested over three studies. The binding and functional results of several studies are compared in an attempt to identify and distinguish those residues that are important in omega-conotoxin function as opposed to those that form part of the structural scaffold. Further to determining what omega-conotoxin residues are important for VSCC binding, the range of possible interactions between the ligand and channel are considered and the factors that influence the selectivity of MVIIA, GVIA and CVID towards N-type VSCCs examined.
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Affiliation(s)
- K J Nielsen
- Centre for Drug Design and Development (3D), Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
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12
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Sasaki T, Kobayashi K, Kohno T, Sato K. Combinatorial synthesis of omega-conotoxin MVIIC analogues and their binding with N- and P/Q-type calcium channels. FEBS Lett 2000; 466:125-9. [PMID: 10648826 DOI: 10.1016/s0014-5793(99)01772-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Omega-conotoxin MVIIC (MVIIC) blocks P/Q-type calcium channels with high affinity and N-type calcium channels with low affinity, while the highly homologous omega-conotoxin MVIIA blocks only N-type calcium channels. We wished to obtain MVIIC analogues more selective for P/Q-type calcium channels than MVIIC to elucidate structural differences among the channels, which discriminate the omega-conotoxins. To prepare a number of MVIIC analogues efficiently, we developed a combinatorial method which includes a random air oxidation step. Forty-seven analogues were prepared in six runs and some of them exhibited higher selectivity for P/Q-type calcium channels than MVIIC in binding assays.
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Affiliation(s)
- T Sasaki
- Mitsubishi Kasei Institute of Life Sciences, 11 Minamiooya, Machida-shi, Tokyo, Japan.
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13
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Three-dimensional structure of α-conotoxin EI determined by1H NMR spectroscopy. Int J Pept Res Ther 1999. [DOI: 10.1007/bf02443507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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14
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Nielsen KJ, Adams D, Thomas L, Bond T, Alewood PF, Craik DJ, Lewis RJ. Structure-activity relationships of omega-conotoxins MVIIA, MVIIC and 14 loop splice hybrids at N and P/Q-type calcium channels. J Mol Biol 1999; 289:1405-21. [PMID: 10373375 DOI: 10.1006/jmbi.1999.2817] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The omega-conotoxins are a set of structurally related, four-loop, six cysteine containing peptides, that have a range of selectivities for different subtypes of the voltage-sensitive calcium channel (VSCC). To investigate the basis of the selectivity displayed by these peptides, we have studied the binding affinities of two naturally occurring omega-conotoxins, MVIIA and MVIIC and a series of 14 MVIIA/MVIIC loop hybrids using radioligand binding assays for N and P/Q-type Ca2+channels in rat brain tissue. A selectivity profile was developed from the ratio of relative potencies at N-type VSCCs (using [125I]GVIA radioligand binding assays) and P/Q-type VSCCs (using [125I]MVIIC radioligand binding assays). In these peptides, loops 2 and 4 make the greatest contribution to VSCC subtype selectivity, while the effects of loops 1 and 3 are negligible. Peptides with homogenous combinations of loop 2 and 4 display clear selectivity preferences, while those with heterogeneous combinations of loops 2 and 4 are less discriminatory. 1H NMR spectroscopy revealed that the global folds of MVIIA, MVIIC and the 14 loop hybrid peptides were similar; however, several differences in local structure were identified. Based on the binding data and the 3D structures of MVIIA, GVIA and MVIIC, we have developed a preliminary pharmacophore based on the omega-conotoxin residues most likely to interact with the N-type VSCC.
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Affiliation(s)
- K J Nielsen
- Centre for Drug Design and Development, University of Queensland, Brisbane, Queensland, 4072, Australia
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15
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Gilquin B, Lecoq A, Desn� F, Guenneugues M, Zinn-Justin S, M�nez A. Conformational and functional variability supported by the BPTI fold: Solution structure of the Ca2+ channel blocker calcicludine. Proteins 1999. [DOI: 10.1002/(sici)1097-0134(19990301)34:4<520::aid-prot11>3.0.co;2-n] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Pallaghy PK, Norton RS. Refined solution structure of omega-conotoxin GVIA: implications for calcium channel binding. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1999; 53:343-51. [PMID: 10231724 DOI: 10.1034/j.1399-3011.1999.00040.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The polypeptide omega-conotoxin GVIA (GVIA) is an N-type calcium channel blocker from the venom of Conus geographus, a fish-hunting cone shell. Here we describe a high-resolution solution structure of this member of the 'inhibitor cystine knot' protein family. The structure, based on NMR data acquired at 600 MHz, has mean pairwise RMS differences of 0.25 +/- 0.06 and 1.07 +/- 0.14 A over the backbone heavy atoms and all heavy atoms, respectively. The solvent-accessible side chains are better defined than in previously published structures and provide an improved basis for docking GVIA with models of the calcium channel. Moreover, some side chain interactions important in GVIA folding in vitro and in stabilizing the native structure are defined clearly in the refined structure. Two qualitatively different backbone conformations in the segment from Thr11 to Asn14 persisted in the restrained simulated annealing calculations until a small number of lower bound constraints was included to prevent close contacts from occurring that did not correspond with peaks in the NOESY spectrum. It is possible that GVIA is genuinely flexible at this segment, spending a finite time in the alternative conformation, and this may influence its interaction with the calcium channel.
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Affiliation(s)
- P K Pallaghy
- Biomolecular Research Institute, Parkville, Vic., Australia
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17
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Norton RS, Pallaghy PK, Baell JB, Wright CE, Lew MJ, Angus JA. Polypeptide ?-conotoxin GVIA as a basis for new analgesic and neuroprotective agents. Drug Dev Res 1999. [DOI: 10.1002/(sici)1098-2299(199903/04)46:3/4<206::aid-ddr6>3.0.co;2-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Sato K, Raymond C, Martin-Moutot N, Sasaki T, Omori A, Ohtake A, Kim JI, Kohno T, Takahashi M, Seagar M. Binding of chimeric analogs of omega-conotoxin MVIIA and MVIIC to the N- and P/Q-type calcium channels. FEBS Lett 1997; 414:480-4. [PMID: 9315745 DOI: 10.1016/s0014-5793(97)01056-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Despite their high sequence homology, the peptide neurotoxins omega-conotoxin MVIIA and MVIIC selectively block N- and P/Q-type calcium channels, respectively. To study the recognition mechanism of calcium channel subtypes, two chimeric analogs of omega-conotoxin MVIIA and MVIIC were synthesized by exchanging their N- and C-terminal halves. Binding assay for both N- and P/Q-type calcium channels showed that amino acid residues restricted to the N-terminal half are important for the recognition of N-type channels, whereas essential residues for P/Q-type channel recognition are widely spread over the whole omega-conotoxin molecule.
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Affiliation(s)
- K Sato
- Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
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19
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Qu Y, Liang S, Ding J, Liu X, Zhang R, Gu X. Proton nuclear magnetic resonance studies on huwentoxin-I from the venom of the spider Selenocosmia huwena: 2. Three-dimensional structure in solution. JOURNAL OF PROTEIN CHEMISTRY 1997; 16:565-74. [PMID: 9263120 DOI: 10.1023/a:1026314722607] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The three-dimensional structure in aqueous solution of native huwentoxin-I, a neurotoxin from the venom of the spider Selenocosmia huwena, has been determined from two-dimensional H NMR data recorded at 500 and 600 MHz. Structural constraints consisting of interproton distances inferred from NOEs and dihedral angles from spin-spin coupling constants were used as input for distance geometry calculation with the program XPLOR 3.1. The best 10 structures have NOE violations < 0.3 A, dihedral violations < 2 degrees, and pairwise root-mean-square differences of 1.08 (+/- 0.20) A over backbone atoms (N, C alpha, C). The molecule adopts a compact structure consisting of a small triple-stranded antiparallel beta-sheet and five beta-turns. A small hydrophobic patch consisting of Phe 6, Trp 28, and Trp 31 is located on one side of the molecule. All six lysine residues are distributed on the molecular surface. The three disulfide bridges are buried within the molecule. The structure contains an "inhibitor cystine knot motif" which is adopted by several other small proteins, such as omega-conotoxin, agatoxin IVA, and gurmarin.
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Affiliation(s)
- Y Qu
- Department of Biology, Peking University, Beijing, China
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20
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Abstract
The selective block of N-type Ca2+ channels by omega-conotoxins has been a hallmark of these channels, critical in delineating their biological roles and molecular characteristics. Here we report that the omega-conotoxin-channel interaction depends strongly on channel gating. N-type channels (alpha1B, alpha2, and beta1) expressed in Xenopus oocytes were blocked with a variety of omega-conotoxins, including omega-CTx-GVIA, omega-CTx-MVIIA, and SNX-331, a derivative of omega-CTx-MVIIC. Changes in holding potential (HP) markedly altered the severity of toxin block and the kinetics of its onset and removal. Notably, strong hyperpolarization renders omega-conotoxin block completely reversible. These effects could be accounted for by a modulated receptor model, in which toxin dissociation from the inactivated state is approximately 60-fold slower than from the resting state. Because omega-conotoxins act exclusively outside cells, our results suggest that voltage-dependent inactivation of Ca2+ channels must be associated with an externally detectable conformational change.
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21
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Lew MJ, Flinn JP, Pallaghy PK, Murphy R, Whorlow SL, Wright CE, Norton RS, Angus JA. Structure-function relationships of omega-conotoxin GVIA. Synthesis, structure, calcium channel binding, and functional assay of alanine-substituted analogues. J Biol Chem 1997; 272:12014-23. [PMID: 9115267 DOI: 10.1074/jbc.272.18.12014] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The structure-function relationships of the N-type calcium channel blocker, omega-conotoxin GVIA (GVIA), have been elucidated by structural, binding and in vitro and in vivo functional studies of alanine-substituted analogues of the native molecule. Alanine was substituted at all non-bridging positions in the sequence. In most cases the structure of the analogues in aqueous solution was shown to be native-like by 1H NMR spectroscopy. Minor conformational changes observed in some cases were characterized by two-dimensional NMR. Replacement of Lys2 and Tyr13 with Ala caused reductions in potency of more than 2 orders of magnitude in three functional assays (sympathetic nerve stimulation of rat isolated vas deferens, right atrium and mesenteric artery) and a rat brain membrane binding assay. Replacement of several other residues with Ala (particularly Arg17, Tyr22 and Lys24) resulted in significant reductions in potency (<100-fold) in the functional assays, but not the binding assay. The potencies of the analogues were strongly correlated between the different functional assays but not between the functional assays and the binding assay. Thus, the physiologically relevant assays employed in this study have shown that the high affinity of GVIA for the N-type calcium channel is the result of interactions between the channel binding site and the toxin at more sites than the previously identified Lys2 and Tyr13.
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Affiliation(s)
- M J Lew
- Department of Pharmacology, University of Melbourne, Parkville 3052, Victoria, Australia.
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22
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Kim JI, Ohtake A, Sato K. Circular dichroism spectra of calcium channel antagonist omega-conotoxins. Biochem Biophys Res Commun 1997; 230:133-5. [PMID: 9020029 DOI: 10.1006/bbrc.1996.5900] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The circular dichroism (CD) spectrum of omega-conotoxin GVIA is quite different from those of omega-conotoxin MVIIA and MVIIC, despite their distinct similarity in three dimensional structures. In order to characterize the unique CD spectrum of omega-conotoxin GVIA, we focused our attention on the aromatic chromophore and analyzed the CD spectra of three synthetic analogs, in which Tyr13, Tyr22, and Tyr27 were individually replaced by alanine. Replacement of Tyr27 caused a significant change in both the near- and far-ultraviolet CD spectrum of omega-conotoxin GVIA and resulted in the omega-conotoxin MVIIA/MVIIC-like pattern, suggesting that Tyr27 has a dominant contribution to the unique CD profile of omega-conotoxin GVIA.
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Affiliation(s)
- J I Kim
- Mitsubishi Kasei Institute of Life Sciences, Machida-shi, Tokyo, Japan
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23
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Abstract
Oxidative folding of omega-conotoxin MVIIC, a highly basic 26-amino acid peptide with three disulfide bonds, predominantly gave two products with mismatched disulfide bonds in 0.1M NH4OAc buffer (pH 7.7) at 21 degrees C both in the presence and absence of redox reagents such as reduced and oxidized glutathione. A low reaction temperature (5 degrees C) and a high salt concentration in buffer such as 2M (NH4)2SO4 were necessary to obtain the correctly folded biologically active product. The folding reaction was found to proceed via a two-stage pathway of (I) the formation and (II) the rearrangement of the mismatched disulfide bonds. Both the reaction temperature and the salt strongly affected the equilibrium between mismatched and correctly formed disulfide bonds in the second stage. Such an effect of salts on the rearrangement reaction could be explained by anion binding at a low concentration and the salting out effect at a high concentration by analyzing the rank order of their effectiveness. The anion-binding effect was also confirmed by examining the folding of the tetra-acetylated peptide at the Lys side chains. CD study suggested that the yield of the biologically active product was correlated with its conformational change as functions of temperature and salt concentration.
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Affiliation(s)
- S Kubo
- Peptide Institute, Inc., Protein Research Foundation, Osaka, Japan
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24
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Olivera BM, Hillyard DR, Marsh M, Yoshikami D. Combinatorial peptide libraries in drug design: lessons from venomous cone snails. Trends Biotechnol 1995; 13:422-6. [PMID: 7546566 DOI: 10.1016/s0167-7799(00)88996-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Many present-day drugs are derived from compounds that are natural products, a traditional source of which is fermentation broths of microorganisms. The venoms of cone snails are a new natural resource of peptides that may have a pharmaceutical potential equivalent to those from traditional sources, particularly for developing drugs that target cell-surface receptors or ion channels. In effect, cone snails have used a combinatorial library strategy to evolve their small, highly bioactive venom peptides. The methods by which the snails have generated thousands of peptides with remarkable specificity and high affinity for their targets may provide important lessons in designing combinatorial libraries for drug development.
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Affiliation(s)
- B M Olivera
- Department of Biology, University of Utah, Salt Lake City 84112, USA
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Basus VJ, Nadasdi L, Ramachandran J, Miljanich GP. Solution structure of omega-conotoxin MVIIA using 2D NMR spectroscopy. FEBS Lett 1995; 370:163-9. [PMID: 7656969 DOI: 10.1016/0014-5793(95)00819-u] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The solution structure of omega-conotoxin MVIIA (SNX-111), a peptide toxin from the fish hunting cone snail Conus magus and a high-affinity blocker of N-type calcium channels, was determined by 2D NMR spectroscopy. The backbones of the best 44 structures match with an average pairwise RMSD of 0.59 angstroms. The structures contain a short segment of triple-stranded beta-sheet involving residues 6-8, 20-21, and 24-25. The structure of this toxin is very similar to that of omega-conotoxin GVIA with which is has only 40% sequence homology, but very similar calcium channel binding affinity and selectivity.
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Affiliation(s)
- V J Basus
- Department of Pharmaceutical Chemistry, University of California, San Francisco 94143, USA
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