title: Diversity of long-chain toxins in Tityus zulianus and Tityus discrepans venoms (Scorpiones, Buthidae): molecular, immunological, and mass spectral analyses.
abstract: In Venezuela, stings by Tityus zulianus scorpions produce cardiorespiratory arrest, whereas envenoming by Tityus discrepans involves gastrointestinal/pancreatic complications, suggesting structural and/or functional differences. We sought to compare their toxin repertoires through immunological, molecular, and mass spectral analyses. First, in vivo tests showed that neutralization of T. zulianus venom toxicity by the anti-T. discrepans antivenom was not complete. To compare T. discrepans and T. zulianus long-chain (sodium channel-active) toxins, their most toxic Sephadex G-50 fractions, TdII and TzII, were subjected to acid-urea PAGE, which showed differences in composition. Amplification of toxin-encoding mRNAs using a leader peptide-based oligonucleotide rendered cDNAs representing twelve T. discrepans and two T. zulianus distinct toxin transcripts, including only one shared component, indicating divergence between T. zulianus and T. discrepans 5' region-encoded, toxin signal peptides. A 3'-UTR polymorphism was also noticed among the transcripts encoding shared components Tz1 and Td4. MALDI-TOF MS profiling of TdII and TzII produced species-specific spectra, with seven of the individual masses matching those predicted by cDNA sequencing. Phylogenetic analysis showed that the unique T. zulianus transcript-encoded sequence, Tz2, is structurally related to Tityus serrulatus and Centruroides toxins. Together with previous reports, this work indicates that T. zulianus and T. discrepans toxin repertoires differ structurally and functionally.
authors.affiliation: Sección de Biomembranas, Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas 1051, Venezuela. Electronic address: borgesa@rect.ucv.ve.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Borges
authors.affiliation: Sección de Biomembranas, Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas 1051, Venezuela.
authors.forename: Carmen C
authors.initials: CC
authors.lastname: García
authors.affiliation: Sección de Biomembranas, Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas 1051, Venezuela.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Lugo
authors.affiliation: Sección de Biomembranas, Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas 1051, Venezuela.
authors.forename: Marcelo J
authors.initials: MJ
authors.lastname: Alfonzo
authors.affiliation: Institute of Biomedical and Life Sciences, Division of Molecular Genetics, University of Glasgow, Glasgow G11 6NU, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Jowers
authors.affiliation: Department of Microbiology, Faculty of Science, Radboud University Nijmegen, Tooernooiveld 1, Nijmegen, The Netherlands.
authors.forename: Huub J M
authors.initials: HJM
authors.lastname: Op den Camp
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D012604:Scorpion Venoms / Q000737:chemistry* / Q000235:genetics*; D012605:Scorpions; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D012604:Scorpion Venoms