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<i>Conus</i> snails produce venoms containing numerous peptides such as the &#945;-conotoxins (&#945;-CTXs), which are well-known nicotinic acetylcholine receptor (nAChR) antagonists. Thirty-eight chromatographic fractions from <i>Conus princeps</i> venom extract were isolated by RP-HPLC. The biological activities of 37 fractions (0.07 &#181;g/&#181;L) were assayed by two-electrode voltage clamp on human &#945;7 nAChRs expressed in <i>Xenopus laevis</i> oocytes. Fractions F7 and F16 notably inhibited the response elicited by acetylcholine by 52.7 &#177; 15.2% and 59.6 &#177; 2.5%, respectively. Fraction F7 was purified, and an active peptide (F7-3) was isolated. Using a combination of Edman degradation, mass spectrometry, and RNASeq, we determined the sequence of peptide F7-3: AVKKTCIRSTOGSNWGRCCLTKMCHTLCCARSDCTCVYRSGKGHGCSCTS, with one hydroxyproline (O) and a free C-terminus. The average mass of this peptide, 10,735.54 Da, indicates that it is a homodimer of identical subunits, with 10 disulfide bonds in total. This peptide is clearly similar to &#945;D-CTXs from species of the Indo-Pacific. Therefore, we called it &#945;D-PiXXA. This toxin slowly and reversibly inhibited the ACh-induced response of the h&#945;7 nAChR subtype, with an IC₅₀ of 6.2 &#956;M, and it does not affect the h&#945;3&#946;2 subtype at 6.5 &#956;M.