A New Member of Gamma-Conotoxin Family Isolated from Conus princeps Displays a Novel Molecular Target

Abstract

A novel conotoxin, named as PiVIIA, was isolated from the venom of Conus princeps, a marine predatory cone snail collected in the Pacific Southern Coast of Mexico. Chymotryptic digest of the S-alkylated peptide in combination with liquid chromatography coupled to tandem mass spectrometry, were used to define the sequencing of this peptide. Eleven N-terminal amino acids were verified by automated Edman degradation. PiVIIA is a 25-mer peptide (CDAOTHYCTNYWγCCSGYCγHSHCW) with six cysteine residues forming three disulphide bonds, a hydroxyproline (O) and two gamma carboxyglutamic acid (γ) residues. Based on the arrangement of six Cys residues (C-C-CC-C-C), this conotoxin might belong to the O2-superfamily. Moreover, PiVIIA has a conserved motif (-γCCS-) that characterizes γ-conotoxins from molluscivorous Conus. Peptide PiVIIA has 45% sequence identity with γ-PnVIIA—the prototype of this family. Biological activity of PiVIIA was assessed by voltage-clamp recording in rat dorsal root ganglion neurons. Perfusion of PiVIIA in the µM range produces a significant increase in the Ca2+ currents, without significantly modifying the Na+, K+ or proton-gated acid sensing ionic currents. These results indicate that PiVIIA is a new conotoxin whose activity deserves further studies to define its potential use as a positive modulator of neuronal activity.

αD-Conotoxins in Species of the Eastern Pacific: The Case of Conus princeps from Mexico

“…This work continues the study of the venom components of Conus princeps , a worm-hunter of the Eastern Pacific, from which one toxin, γ-CTX PiVIIA, has been recently purified and characterized at the chemical and electrophysiological levels [19,20]. Other toxins from this species have been identified by RT-PCR and transcriptomics [14,18,21].…”

“…As mentioned above, there are only two reports on α-CTXs from C. princeps at the protein level and they refer to the same peptide with activity over two different molecular targets [19,20]. Therefore, in this work, we isolated two venom duct extract fractions (F7 and F16) that inhibited ≥50.0% the ACh-induced response of the hα7 nAChR subtype, and purified and characterized the least scarce of the two most potent fractions.…”

Antimycobacterial Activity: A New Pharmacological Target for Conotoxins Found in the First Reported Conotoxin from Conasprella ximenes

“…Manual interpretation of the MS/MS spectra were conducted to extract a reliable sequence tag that was confirmed using the b n and y″ n backbone fragment ions. The mass accuracy (0.01–0.02 Da), as well as other aspects used in the de novo sequencing of peptides were also considered to extract this partial sequence [ 46 , 47 ]. The conotoxin of interest was identified in the transcriptome database with the aid of MASCOT [ 25 ], using the sequence query option.…”

Discovery Methodology of Novel Conotoxins from Conus Species

“…The purified conotoxins are subjected to de novo sequencing through Edman degradation [ 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 ] or MS sequencing [ 81 , 88 , 89 , 90 ] after sequential disulfide bond reduction, hydrosulphonyl alkylation, and enzymolysis, which make sequencing process much easier. PTMs are assigned with the aid of MS techniques [ 59 , 65 , 66 , 69 , 70 , 71 , 75 , 76 , 77 , 78 , 80 , 83 , 89 , 90 , 91 , 92 ]. The targeted conotoxins are then chemically synthesized through SPPS, following the subsequent oxidative...…”