Structural and Functional Characterization of a Novel ?-Conotoxin Mr1.7 from Conus marmoreus Targeting Neuronal nAChR ?3?2, ?9?10 and ?6/?3?2?3 Subtypes.

ABSTRACT: In the present study, we synthesized and, structurally and functionally characterized a novel ?4/7-conotoxin Mr1.7 (PECCTHPACHVSHPELC-NH2), which was previously identified by cDNA libraries from Conus marmoreus in our lab. The NMR solution structure showed that Mr1.7 contained a 310-helix from residues Pro7 to His10 and a type I ?-turn from residues Pro14 to Cys17. Electrophysiological results showed that Mr1.7 selectively inhibited the ?3?2, ?9?10 and ?6/?3?2?3 neuronal nicotinic acetylcholine receptors (nAChRs) with an IC50 of 53.1 nM, 185.7 nM and 284.2 nM, respectively, but showed no inhibitory activity on other nAChR subtypes. Further structure-activity studies of Mr1.7 demonstrated that the PE residues at the N-terminal sequence of Mr1.7 were important for modulating its selectivity, and the replacement of Glu2 by Ala resulted in a significant increase in potency and selectivity to the ?3?2 nAChR. Furthermore, the substitution of Ser12 with Asn in the loop2 significantly increased the binding of Mr1.7 to ?3?2, ?3?4, ?2?4 and ?7 nAChR subtypes. Taken together, this work expanded our knowledge of selectivity and provided a new way to improve the potency and selectivity of inhibitors for nAChR subtypes.

SUBMITTER: Wang S 

PROVIDER: S-EPMC4483627 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature