NMR Solution Conformation of an Antitoxic Analogue of α-Conotoxin GI: Identification of a Common Nicotinic Acetylcholine Receptor α<sub>1</sub>-Subunit Binding Surface for Small Ligands and α-Conotoxins<sup>,</sup>

Mok, K. Hun; Han, Kyung-Hwa

doi:10.1021/bi990558n

Cited by 17 publications

(21 citation statements)

References 55 publications

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“…Because of trans-cis isomerization of prolines, minor peaks originating from a cis-conformer were noted. Similar cis conformers have been observed in other ␣-/␣A-conotoxins as well (13,27,34,41). Detailed analyses of NMR data and structure calculation have been carried out for the trans-isomer.…”

Section: Nmr Spectroscopy-completesupporting

confidence: 64%

“…Unfortunately, varying sizes and physicochemical properties of most nAChR ligands prevent straightforward comparison of their three-dimensional structures. Nevertheless, structural comparison among various ␣-/␣A-conotoxins is possible even though comparison has been limited because of the differences in the disulfide framework (13,24,27,28,34). Here, we report a high resolution NMR structure of ␣-conotoxin EI, an ␣4/7 subfamily member with a unique ␣ 1 /␦ specificity toward Torpedo neuromuscular nAChR (14).…”

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confidence: 99%

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Solution Conformation of α-Conotoxin EI, a Neuromuscular Toxin Specific for the α1/δ Subunit Interface of Torpedo Nicotinic Acetylcholine Receptor

Park¹,

Suk²,

Jacobsen³

et al. 2001

Journal of Biological Chemistry

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A high resolution structure of ␣-conotoxin EI has been determined by 1 H NMR spectroscopy and molecular modeling. ␣-Conotoxin EI has the same disulfide framework as ␣4/7 conotoxins targeting neuronal nicotinic acetylcholine receptors but antagonizes the neuromuscular receptor as do the ␣3/5 and ␣A conotoxins. The unique binding preference of ␣-conotoxin EI to the ␣ 1 /␦ subunit interface of Torpedo neuromuscular receptor makes it a valuable structural template for superposition of various ␣-conotoxins possessing distinct receptor subtype specificities. Structural comparison of ␣-conotoxin EI with the ␥-subunit favoring ␣-conotoxin GI suggests that the Torpedo ␦-subunit preference of the former originates from its second loop. Superposition of three-dimensional structures of seven ␣-conotoxins reveals that the estimated size of the toxin-binding pocket in nicotinic acetylcholine receptor is ϳ20 Å (height) ؋ 20 Å (width) ؋ 15 Å (thickness).The nicotinic acetylcholine receptors (nAChRs) 1 are a well studied family of ligand-gated ion channels comprising a diverse set of molecular subtypes (1). The best characterized is the receptor at the neuromuscular junction, with four different subunits in a pentameric array, i.e. (␣ 1 ) 2 ␤ 1␥ ␦. Less well understood and more diverse are the neuronal nAChRs that assemble in exogenous expression systems with a general composition of (␣ m ) 2 (␤ n ) 3 , where m ϭ 2-6 and n ϭ 2-4, or (␣ 7 ) 5 (2, 3). A large variety of ligands bind to such diverse nAChRs via unknown mechanisms. A better understanding of the ligandbinding mechanism would be possible if a suitable three-dimensional structure of nAChR were available. Although cryoelectron microscopic images of nAChR show the spatial arrangement of five subunits of the receptor and some aspects of the ligand-binding pockets (4, 5), they are as yet insufficient for describing ligand-receptor interactions in atomic detail. In this regard, the recently determined crystal structure of acetylcholine-binding protein is expected to provide useful insight into ligand-nAChR interactions (6).Small peptide toxins of Conus origin known as the ␣-and ␣A-conotoxins are highly useful tools for exploring ligandnAChR interactions (7,8). A well defined subgroup of ␣-conotoxins, referred to as the ␣3/5 2 subfamily conotoxins (Table I), are antagonists of neuromuscular receptors and show, except for ␣-conotoxin SI (9, 10), binding preference to the ␣ 1 /␥ subunit interface of Torpedo nAChR. On the other hand, more recently found ␣A-conotoxins differ from the ␣3/5 subfamily conotoxins in the amino acid sequences (11, 12) as well as in their threedimensional structures (13). The ␣A-conotoxins, nevertheless, target neuromuscular receptors. A third subfamily of ␣-conotoxins known as the ␣4/7 subfamily has also been found; members of this subfamily target subtypes of neuronal and muscle nAChRs (14 -17). The ␣4/7 subfamily contains two disulfide bonds like the ␣3/5 subfamily but has a different spacing between the disulfide bonds.Even though a high resolutio...

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Section: Nmr Spectroscopy-completesupporting

confidence: 64%

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confidence: 99%

Solution Conformation of α-Conotoxin EI, a Neuromuscular Toxin Specific for the α1/δ Subunit Interface of Torpedo Nicotinic Acetylcholine Receptor

Park¹,

Suk²,

Jacobsen³

et al. 2001

Journal of Biological Chemistry

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“…Despite the overall differences or local similarity among these toxins, it is certainly difficult to unambiguously define the respective subtype selectivities based only on such structural features (18). Binding determinants within the ␣4/7 subfamily are subtle and may not be immediately discernible, as can be judged from the fact that the overall structural fold is same, whereas only types of amino acids are varied.…”

Section: Solution Conformation Of ␣-Conotoxin Auibmentioning

confidence: 99%

“…Through structural elucidation of these highly selective ␣-conotoxins and their analogs (17,18), we have been using the reverse-mapping approach first to identify receptor subtype specific determinants in the ligands and second to indirectly probe the regions in nAChR responsible for binding agonists * This research was supported in part by Grant NB0980 from the Ministry of Science and Technology, Korea. The costs of publication of this article were defrayed in part by the payment of page charges.…”

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confidence: 99%

Nuclear Magnetic Resonance Solution Conformation of α-Conotoxin AuIB, an α3β4 Subtype-selective Neuronal Nicotinic Acetylcholine Receptor Antagonist

Cho¹,

Mok²,

Olivera³

et al. 2000

Journal of Biological Chemistry

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The neuronal nicotinic acetylcholine receptors constitute a highly diverse group, with subtypes consisting of pentameric combinations of ␣ and ␤ subunits. ␣-Conotoxins are a homologous series of small peptides that antagonize these receptors. We present the three-dimensional solution structure of ␣-conotoxin AuIB, the first 15-residue ␣-conotoxin known to selectively block the ␣ 3 ␤ 4 nicotinic acetylcholine receptor subtype. The pairwise backbone and heavy-atom root mean square deviation for an ensemble of 20 structures are 0.269 and 0.720 Å, respectively. The overall fold of ␣-conotoxin AuIB closely resembles that of the ␣4/7 subfamily ␣-conotoxins. However, the absence of Tyr 15 , normally present in other ␣4/7 members, results in tight bending of the backbone at the C terminus and effectively renders Asp 14 to assume the spatial location of Tyr 15 present in other neuronal ␣4/7 ␣-conotoxins. Structural comparison of ␣-conotoxin AuIB with the ␣ 3 ␤ 2 subtype-specific ␣-conotoxin MII shows different electrostatic surface charge distributions, which may be important in differential receptor subtype recognition.The ␣-conotoxins are small neuropharmacologically active peptides of Conus origin that antagonize the nicotinic acetylcholine receptor (nAChR) 1 (1). The natural diversity of biosynthesized conotoxin peptides has led to the classification of a wide spectrum of disulfide-bridged peptides, which attack various ligand and ion-gated channels and receptors (1). The nicotinic acetylcholine receptors exhibit considerable diversity in their own right because of the different compositions found in the pentameric subunits constituting each nAChR subtype (2). Although the mammalian neuromuscular subtype comprises (␣ 1 ) 2 ␤␥␦ or (␣ 1 ) 2 ␤⑀␦ subunits, the neuronal subtypes are comparatively more diverse with their hetero-or homopentameric combinations of ␣ (␣ 2 ϳ ␣ 9 ) or ␤ (␤ 2 ϳ ␤ 4 ) subunits (3, 4). The general conotoxin strategy of diversification is "combinatorial" (5), in which amino acid residues are varied within a given disulfide framework to specifically and selectively bind various subtypes of the target channel or receptor. For the case of ␣-conotoxins, target selectivity is essentially defined depending on which subunit interface of the nAChR (e.g. ␣ 1 /␥, ␣ 1 /␦, and ␣ 3 /␤ 2 ) each individual ␣-conotoxin preferentially binds to (1). Highly selective ␣-conotoxins that permit differential blocking of diverse nAChR subtypes have served as effective tools in studying these receptors (1).Of recent particular interest are the ␣-conotoxins that act on neuronal nAChRs. For example, ␣-conotoxin AuIB specifically targets the ␣ 3 ␤ 4 subtype (6), whereas ␣-conotoxin MII selectively blocks the ␣ 3 ␤ 2 subtype (7). On the other hand, ␣-conotoxin ImI, the smallest of all ␣-conotoxins and distinct because of its ␣4/3 disulfide framework 2 , is a specific antagonist of the homomeric ␣ 7 subtype (8). In addition, other neuronal ␣-conotoxins such as PnIA (9), PnIB (9), and EpI (10) that are less selective to a particu...

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“…Ligand binding modes of these residues have been confirmed in recent homology modeled structures of nAChRs (31) and the x-ray structures of AChBP bound to α-conotoxins (23,25,32) or α-cobratoxin (33). Another strategy for studying nAChR-ligand interactions has been to identify potential receptor-binding pharmacophores within various ligands including α-conotoxins (16,17,19,21,(34)(35)(36)(37). Here, we have generated high-resolution structures of ligand-nAChR complexes using α-conotoxin GIC, a well-known antagonistic ligand of nAChRs, and the extracellular domains of nAChRs that are homology modeled using the α1 subunit of mouse, which has much higher sequence homology with nAChR subunits than acetylcholine binding protein (AChBP).…”

Section: Resultsmentioning

confidence: 99%

Molecular docking study on the α3β2 neuronal nicotinic acetylcholine receptor complexed with α-Conotoxin GIC

Lee¹,

Lee²,

Kim³

et al. 2012

BMB Reports

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Nicotinic acetylcholine receptors (nAChRs) are a diverse family of homo-or heteropentameric ligand-gated ion channels. Understanding the physiological role of each nAChR subtype and the key residues responsible for normal and pathological states is important. α-Conotoxin neuropeptides are highly selective probes capable of discriminating different subtypes of nAChRs. In this study, we performed homology modeling to generate the neuronal α3, β2 and β4 subunits using the x-ray structure of the α1 subunit as a template. The structures of the extracellular domains containing ligand binding sites in the α3β2 and α3β4 nAChR subtypes were constructed using MD simulations and ligand docking processes in their free and ligand-bound states using α-conotoxin GIC, which exhibited the highest α3β2 vs. α3β4 discrimination ratio. The results provide a reasonable structural basis for such a discriminatory ability, supporting the idea that the present strategy can be used for future investigations on nAChR-ligand complexes.[BMB reports 2012; 45(5): 275-280]

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NMR Solution Conformation of an Antitoxic Analogue of α-Conotoxin GI: Identification of a Common Nicotinic Acetylcholine Receptor α₁-Subunit Binding Surface for Small Ligands and α-Conotoxins^,

Cited by 17 publications

References 55 publications

Solution Conformation of α-Conotoxin EI, a Neuromuscular Toxin Specific for the α1/δ Subunit Interface of Torpedo Nicotinic Acetylcholine Receptor

Solution Conformation of α-Conotoxin EI, a Neuromuscular Toxin Specific for the α1/δ Subunit Interface of Torpedo Nicotinic Acetylcholine Receptor

Nuclear Magnetic Resonance Solution Conformation of α-Conotoxin AuIB, an α3β4 Subtype-selective Neuronal Nicotinic Acetylcholine Receptor Antagonist

Molecular docking study on the α3β2 neuronal nicotinic acetylcholine receptor complexed with α-Conotoxin GIC

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NMR Solution Conformation of an Antitoxic Analogue of α-Conotoxin GI: Identification of a Common Nicotinic Acetylcholine Receptor α1-Subunit Binding Surface for Small Ligands and α-Conotoxins,

Cited by 17 publications

References 55 publications

Solution Conformation of α-Conotoxin EI, a Neuromuscular Toxin Specific for the α1/δ Subunit Interface of Torpedo Nicotinic Acetylcholine Receptor

Solution Conformation of α-Conotoxin EI, a Neuromuscular Toxin Specific for the α1/δ Subunit Interface of Torpedo Nicotinic Acetylcholine Receptor

Nuclear Magnetic Resonance Solution Conformation of α-Conotoxin AuIB, an α3β4 Subtype-selective Neuronal Nicotinic Acetylcholine Receptor Antagonist

Molecular docking study on the α3β2 neuronal nicotinic acetylcholine receptor complexed with α-Conotoxin GIC

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Product

Resources

About

NMR Solution Conformation of an Antitoxic Analogue of α-Conotoxin GI: Identification of a Common Nicotinic Acetylcholine Receptor α₁-Subunit Binding Surface for Small Ligands and α-Conotoxins^,