Identification, by RT-PCR, of eight novel I₂-conotoxins from the worm-hunting cone snails Conus brunneus, Conus nux, and Conus princeps from the eastern Pacific (Mexico).
Marine snails of the genus Conus (∼500 species) are tropical predators that produce venoms for capturing prey, defense and competitive interactions. These venoms contain 50-200 different peptides ("conotoxins") that generally comprise 7-40 amino acid residues (including 0-5 disulfide bridges), and that frequently contain diverse posttranslational modifications, some of which have been demonstrated to be important for folding, stability, and biological activity. Most conotoxins affect voltage- and ligand-gated ion channels, G protein-coupled receptors, and neurotransmitter transporters, generally with high affinity and specificity. Due to these features, several conotoxins are used as molecular tools, diagnostic agents, medicines, and models for drug design. Based on the signal sequence of their precursors, conotoxins have been classified into genetic superfamilies, whereas their molecular targets allow them to be classified into pharmacological families. The objective of this work was to identify and analyze partial cDNAs encoding precursors of conotoxins belonging to I superfamily from three vermivorous species of the Mexican Pacific coast: C. brunneus, C. nux and C. princeps. The precursors identified contain diverse numbers of amino acid residues (C. brunneus, 65 or 71; C. nux, 70; C. princeps, 72 or 73), and all include a highly conserved signal peptide, a C-terminal propeptide, and a mature toxin. All the latter have one of the typical Cys frameworks of the I-conotoxins (C-C-CC-CC-C-C). The prepropeptides belong to the I2-superfamily, and encode eight different hydrophilic and acidic mature toxins, rather similar among them, and some of which have similarity with I2-conotoxins targeting voltage- and voltage-and-calcium-gated potassium channels.
Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM Juriquilla, Querétaro 76230, Mexico; Laboratorio de Genética Molecular, Instituto Tecnológico de Conkal, Conkal, Yucatán 97345, Mexico.
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Zamora-Bustillos
Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM Juriquilla, Querétaro 76230, Mexico.
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Rivera-Reyes
Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM Juriquilla, Querétaro 76230, Mexico. Electronic address: maguilar@unam.mx.
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Aguilar
Departamento de Estudios para el Desarrollo Sustentable de Zonas Costeras. CUCSUR-Universidad de Guadalajara, San Patricio-Melaque, Jalisco 48980, Mexico.
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Michel-Morfín
Departamento de Estudios para el Desarrollo Sustentable de Zonas Costeras. CUCSUR-Universidad de Guadalajara, San Patricio-Melaque, Jalisco 48980, Mexico; Posgrado en Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Nayarit, Mexico.
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Landa-Jaime
Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM Juriquilla, Querétaro 76230, Mexico.
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Falcón
Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM Juriquilla, Querétaro 76230, Mexico.
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Heimer
D000595:Amino Acid Sequence; D000818:Animals; D020916:Conotoxins / Q000737:chemistry / Q000235:genetics*; D052078:Conus Snail / Q000235:genetics; D018076:DNA, Complementary; D008800:Mexico; D008969:Molecular Sequence Data; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D017386:Sequence Homology, Amino Acid; D012908:Snails / Q000235:genetics*
D020916:Conotoxins; D018076:DNA, Complementary; D024642:Potassium Channels, Voltage-Gated
Conotoxin precursor; Conus brunneus; Conus nux; Conus princeps; I-conotoxin; cDNA cloning