Alanine scan of ?-conotoxin RegIIA reveals a selective ?3?4 nicotinic acetylcholine receptor antagonist.

ABSTRACT: Activation of the ?3?4 nicotinic acetylcholine receptor (nAChR) subtype has recently been implicated in the pathophysiology of various conditions, including development and progression of lung cancer and in nicotine addiction. As selective ?3?4 nAChR antagonists, ?-conotoxins are valuable tools to evaluate the functional roles of this receptor subtype. We previously reported the discovery of a new ?4/7-conotoxin, RegIIA. RegIIA was isolated from Conus regius and inhibits acetylcholine (ACh)-evoked currents mediated by ?3?4, ?3?2, and ?7 nAChR subtypes. The current study used alanine scanning mutagenesis to understand the selectivity profile of RegIIA at the ?3?4 nAChR subtype. [N11A] and [N12A] RegIIA analogs exhibited 3-fold more selectivity for the ?3?4 than the ?3?2 nAChR subtype. We also report synthesis of [N11A,N12A]RegIIA, a selective ?3?4 nAChR antagonist (IC50 of 370 nM) that could potentially be used in the treatment of lung cancer and nicotine addiction. Molecular dynamics simulations of RegIIA and [N11A,N12A]RegIIA bound to ?3?4 and ?3?2 suggest that destabilization of toxin contacts with residues at the principal and complementary faces of ?3?2 (?3-Tyr(92), Ser(149), Tyr(189), Cys(192), and Tyr(196); ?2-Trp(57), Arg(81), and Phe(119)) may form the molecular basis for the selectivity shift.

SUBMITTER: Kompella SN 

PROVIDER: S-EPMC4294472 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature