1a0m

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1.1 ANGSTROM CRYSTAL STRUCTURE OF A-CONOTOXIN [TYR15]-EPI

Overview

Conotoxins are valuable probes of receptors and ion channels because of, their small size and highly selective activity. alpha-Conotoxin EpI, a, 16-residue peptide from the mollusk-hunting Conus episcopatus, has the, amino acid sequence GCCSDPRCNMNNPDY(SO3H)C-NH2 and appears to be an, extremely potent and selective inhibitor of the alpha3beta2 and, alpha3beta4 neuronal subtypes of the nicotinic acetylcholine receptor, (nAChR). The desulfated form of EpI ([Tyr15]EpI) has a potency and, selectivity for the nAChR receptor similar to those of EpI. Here we, describe the crystal structure of [Tyr15]EpI solved at a resolution of 1.1, A using SnB. The asymmetric unit has a total of 284 non-hydrogen atoms, making this one of the largest structures solved de novo by direct, methods. The [Tyr15]EpI structure brings to six the number of, alpha-conotoxin structures that have been determined to date. Four of, these, [Tyr15]EpI, PnIA, PnIB, and MII, have an alpha4/7 cysteine, framework and are selective for the neuronal subtype of the nAChR. The, structure of [Tyr15]EpI has the same backbone fold as the other, alpha4/7-conotoxin structures, supporting the notion that this conotoxin, cysteine framework and spacing give rise to a conserved fold. The surface, charge distribution of [Tyr15]EpI is similar to that of PnIA and PnIB but, is likely to be different from that of MII, suggesting that [Tyr15]EpI and, MII may have different binding modes for the same receptor subtype.

About this Structure

1A0M is a Single protein structure of sequence from Conus episcopatus with NH2 as ligand. Full crystallographic information is available from OCA.

Reference

The 1.1 A resolution crystal structure of [Tyr15]EpI, a novel alpha-conotoxin from Conus episcopatus, solved by direct methods., Hu SH, Loughnan M, Miller R, Weeks CM, Blessing RH, Alewood PF, Lewis RJ, Martin JL, Biochemistry. 1998 Aug 18;37(33):11425-33. PMID:9708977

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