Identifying Key Amino Acid Residues That Affect α-Conotoxin AuIB Inhibition of α3β4 Nicotinic Acetylcholine Receptors

Abstract

Background: ␣-Conotoxin AuIB interacts with ␣3␤4 nAChRs and GABA B receptors, but structural determinants of these interactions are unknown. Results: Using alanine scanning mutagenesis and molecular dynamics, we identified residues crucial for AuIB⅐␣3␤4 nAChR interaction. Conclusion:We identified the key residues that mediate AuIB⅐␣3␤4 nAChR interaction. Significance: Ability to direct ␣-conotoxin binding to nAChRs or GABA B receptors will improve analgesic conopeptides.

Key Structural Determinants in the Agonist Binding Loops of Human β2 and β4 Nicotinic Acetylcholine Receptor Subunits Contribute to α3β4 Subtype Selectivity of α-Conotoxins

“…7, C and D, and (33). An alanine substitution substantially reduced ␣3␤4 inhibition and decreased subtype specificity.…”

“…Thereby, AuIB Phe 9 forms contact with ␤4 Lys 59 and ␤4 Leu 119 , but the crucial -interaction with ␤4 Trp 57 is absent. As the tryptophan residue was indispensable for the inhibitory effect of AuIB at the rat homologue, and ␤4 Lys 59 appeared to play an auxiliary role (33), the lack of interaction between AuIB F9 and ␤4 Trp 57 could explain the loss of AuIB activity at the h␣3␤4 subtype. At h␣3␤2, our modeling revealed contacts between AuIB and ␤2 Trp 57 , Thr 59 , and other residues ( Fig.…”

“…An alanine substitution substantially reduced ␣3␤4 inhibition and decreased subtype specificity. Additional AuIB analogues with other side chains at this position demonstrated that size, aromaticity, and hydrophobicity at position 9 of AuIB are important for interaction between the peptide and ␤4 subunit of the rat ␣3␤4 pentamer (33).…”

Molecular Basis for Differential Sensitivity of α-Conotoxin RegIIA at Rat and Human Neuronal Nicotinic Acetylcholine Receptors

“…However, at a3b4, this residue is not the major determinant for AuIB potency. The main determinants for AuIB potency are on the b4 subunit (Grishin et al, 2013). These findings indicate the a3 residue at position 198 does not appear to have the same Fig.…”

“…We used MD simulation and alanine-scanning analysis to identify interactions between residue a3-Q198 and a-conotoxin AuIB at the rat a3b4 nAChR subtype (Grishin et al, 2013). However, at a3b4, this residue is not the major determinant for AuIB potency.…”