title: A novel conotoxin from Conus delessertii with posttranslationally modified lysine residues.
abstract: A major peptide, de13a from the crude venom of Conus delessertii collected in the Yucatan Channel, Mexico, was purified. The peptide had a high content of posttranslationally modified amino acids, including 6-bromotryptophan and a nonstandard amino acid that proved to be 5-hydroxylysine. This is the first report of 5-hydroxylysine residues in conotoxins. The sequence analysis, together with cDNA cloning and a mass determination (monoisotopic mass of 3486.76 Da), established that the mature toxin has the sequence DCOTSCOTTCANGWECCKGYOCVNKACSGCTH, where O is 4-hydroxyproline, W 6-bromotryptophan, and K 5-hydroxylysine, the asterisk represents the amidated C-terminus, and the calculated monoisotopic mass is 3487.09 Da. The eight Cys residues are arranged in a pattern (C-C-C-CC-C-C-C) not described previously in conotoxins. This arrangement, for which we propose the designation of framework #13 or XIII, differs from the ones (C-C-CC-CC-C-C and C-C-C-C-CC-C-C) present in other conotoxins which also contain eight Cys residues. This peptide thus defines a novel class of conotoxins, with a new posttranslational modification not previously found in other Conus peptide families.
authors.affiliation: Laboratory of Marine Neuropharmacology, Institute of Neurobiology, Universidad Nacional Autónoma de México, Juriquilla, Qro. 76230, Mexico. maguilar@servidor.unam.mx
authors.forename: Manuel B
authors.initials: MB
authors.lastname: Aguilar
authors.forename: Estuardo
authors.initials: E
authors.lastname: López-Vera
authors.forename: Ernesto
authors.initials: E
authors.lastname: Ortiz
authors.forename: Baltazar
authors.initials: B
authors.lastname: Becerril
authors.forename: Lourival D
authors.initials: LD
authors.lastname: Possani
authors.forename: Baldomero M
authors.initials: BM
authors.lastname: Olivera
authors.forename: Edgar P
authors.initials: EP
authors.lastname: Heimer de la Cotera
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D020916:Conotoxins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology; D012908:Snails / Q000378:metabolism
chemical_list: D000596:Amino Acids; D020916:Conotoxins; D010455:Peptides