Two potent alpha3/5 conotoxins from piscivorous Conus achatinus

Area of Science:

• Marine biology
• Neuroscience
• Biochemistry

Background:

• Cone snails utilize diverse conotoxins for prey capture and defense.
• Alpha3/5 conotoxins specifically target muscle nicotinic acetylcholine receptors.
• The structure-function relationship of alpha3/5 conotoxin from Conus achatinus remains uncharacterized.

Purpose of the Study:

• To synthesize and characterize alpha3/5 conotoxins from Conus achatinus.
• To investigate the binding site and potency of these conotoxins on nicotinic acetylcholine receptors.

Main Methods:

• Synthesis of two pentadecamer peptides (Ac1.1a and Ac1.1b) with disulfide bonds.
• Functional assays using recombinant mouse muscle nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes.
• Site-directed mutagenesis to assess the role of the N-terminus.

Main Results:

• Ac1.1a and Ac1.1b were successfully synthesized.
• Both peptides demonstrated potent inhibition of nicotinic acetylcholine receptor activity (IC50 values of 36 nM and 26 nM).
• The N-terminus of Ac1.1b was found not to be critical for activity, and the toxins preferentially bind to the alpha1-delta subunit interface.

Conclusions:

• Synthesized alpha3/5 conotoxins from Conus achatinus are potent blockers of muscle nicotinic acetylcholine receptors.
• These conotoxins exhibit a preference for the alpha1-delta subunit interface.
• The novel synthesized peptides serve as valuable tools for studying nicotinic acetylcholine receptor structure and function.