title: cDNA cloning, sequence analysis and molecular modeling of a new peptide from the scorpion Buthotus saulcyi venom.
abstract: In this study, the cDNA of a new peptide from the venom of the scorpion, Buthotus saulcyi, was cloned and sequenced. It codes for a 64 residues peptide (Bsaul1) which shares high sequence similarity with depressant insect toxins of scorpions. The differences between them mainly appear in the loop1 which connects the beta-strand1 to the alpha-helix and seems to be functionally important in long chain scorpion neurotoxins. This loop is three amino acids longer in Bsaul1 compared to other depressant toxins. A comparative amino acid sequence analysis done on Bsaul1 and some of alpha-, beta-, excitatory and depressant toxins of scorpions showed that Bsaul1 contains all the residues which are highly conserved among long chain scorpion neurotoxins. Structural model of Bsaul1 was generated using Ts1 (a beta-toxin that competes with the depressant insect toxins for binding to Na(+) channels) as template. According to the molecular model of Bsaul1, the folding of the polypeptide chain is being composed of an anti-parallel three-stranded beta-sheet and a stretch of alpha- helix, tightly bound by a set of four disulfide bridges. A striking similarity in the spatial arrangement of some critical residues was shown by superposition of the backbone conformation of Bsaul1 and Ts1.
authors.affiliation: Institute of Biochemistry and Biophysics, University of Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Nikkhah
authors.forename: Hossein Naderi
authors.initials: HN
authors.lastname: Manesh
authors.forename: Majid
authors.initials: M
authors.lastname: Taghdir
authors.forename: Mehdi
authors.initials: M
authors.lastname: Talebzadeh
authors.forename: Majid Sadeghi
authors.initials: MS
authors.lastname: Zadeh
authors.forename: Janatan
authors.initials: J
authors.lastname: Schaller
authors.forename: Mohamad N
authors.initials: MN
authors.lastname: Sarbolouki
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry* / Q000235:genetics; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011487:Protein Conformation; D012604:Scorpion Venoms / Q000737:chemistry*; D012605:Scorpions / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
chemical_list: D018076:DNA, Complementary; D009498:Neurotoxins; D010455:Peptides; D012604:Scorpion Venoms