Dataset Information

Molecular interaction of ?-conotoxin RgIA with the rat ?9?10 nicotinic acetylcholine receptor.

ABSTRACT: The ?9?10 nicotinic acetylcholine receptor (nAChR) was first identified in the auditory system, where it mediates synaptic transmission between efferent olivocochlear cholinergic fibers and cochlea hair cells. This receptor gained further attention due to its potential role in chronic pain and breast and lung cancers. We previously showed that ?-conotoxin (?-CTx) RgIA, one of the few ?9?10 selective ligands identified to date, is 300-fold less potent on human versus rat ?9?10 nAChR. This species difference was conferred by only one residue in the (-), rather than (+), binding region of the ?9 subunit. In light of this unexpected discovery, we sought to determine other interacting residues with ?-CTx RgIA. A previous molecular modeling study, based on the structure of the homologous molluscan acetylcholine-binding protein, predicted that RgIA interacts with three residues on the ?9(+) face and two residues on the ?10(-) face of the ?9?10 nAChR. However, mutations of these residues had little or no effect on toxin block of the ?9?10 nAChR. In contrast, mutations of homologous residues in the opposing nAChR subunits (?10 ?197, P200 and ?9 T61, D121) resulted in 19- to 1700-fold loss of toxin activity. Based on the crystal structure of the extracellular domain (ECD) of human ?9 nAChR, we modeled the rat ?9?10 ECD and its complexes with ?-CTx RgIA and acetylcholine. Our data support the interaction of ?-CTx RgIA at the ?10/?9 rather than the ?9/?10 nAChR subunit interface, and may facilitate the development of selective ligands with therapeutic potential.

SUBMITTER: Azam L

PROVIDER: S-EPMC4407738 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Molecular interaction of α-conotoxin RgIA with the rat α9α10 nicotinic acetylcholine receptor.

Azam Layla L Papakyriakou Athanasios A Zouridakis Marios M Giastas Petros P Tzartos Socrates J SJ McIntosh J Michael JM

Molecular pharmacology 20150304 5

The α9α10 nicotinic acetylcholine receptor (nAChR) was first identified in the auditory system, where it mediates synaptic transmission between efferent olivocochlear cholinergic fibers and cochlea hair cells. This receptor gained further attention due to its potential role in chronic pain and breast and lung cancers. We previously showed that α-conotoxin (α-CTx) RgIA, one of the few α9α10 selective ligands identified to date, is 300-fold less potent on human versus rat α9α10 nAChR. This species ...[more]

PMID: 25740413

Similar Datasets

Project description:α-Conotoxins (α-CTxs) are small disulfide-rich peptides from venom of Conus species that target nicotinic acetylcholine receptors (nAChRs). The muscle-type nAChRs have been recognized as a potential target for several diseases, such as myogenic disorders, muscle dystrophies, and myasthenia gravis. EI, an α4/7-CTx, mainly blocks α1β1δε nAChRs and has an extra N-terminal extension of three amino acids. In this study, the alanine scanning (Ala-scan) mutagenesis was applied in order to identify key residues of EI for binding with mouse α1β1δε nAChR. The Ala-substituted analogues were tested for their abilities of modulating muscle and neuronal nAChRs in Xenopus laevis oocytes using two-electrode voltage clamp (TEVC) recordings. Electrophysiological results indicated that the vital residues for functional activity of EI were His-7, Pro-8, Met-12, and Pro-15. These changes exhibited a significant decrease in potency of EI against mouse α1β1δε nAChR. Interestingly, replacing the critical serine (Ser) at position 13 with an alanine (Ala) residue resulted in a 2-fold increase in potency at the α1β1δε nAChR, and showed loss of activity on α3β2 and α3β4 nAChRs. Selectivity and potency of [S13A] EI was improved compared with wild-type EI (WT EI). In addition, the structure-activity relationship (SAR) of EI revealed that the "Arg1-Asn2-Hyp3" residues at the N-terminus conferred potency at the muscle-type nAChRs, and the deletion analogue △1-3 EI caused a total loss of activity at the α1β1δε nAChR. Circular dichroism (CD) spectroscopy studies demonstrated that activity loss of truncated analogue △1-3 EI for α1β1δε nAChR is attributed to disturbance of the secondary structure. In this report, an Ala-scan mutagenesis strategy is presented to identify crucial residues that are significantly affecting potency of E1 for mouse α1β1δε nAChR. It may also be important in remodeling of some novel ligands for inhibiting muscle-type nAChRs.

Dataset Information

Molecular interaction of ?-conotoxin RgIA with the rat ?9?10 nicotinic acetylcholine receptor.

Publications

Molecular interaction of α-conotoxin RgIA with the rat α9α10 nicotinic acetylcholine receptor.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets