Identification of BmKAPi, a novel type of scorpion venom peptide with peculiar disulfide bridge pattern from Buthus martensii Karsch.
A novel cDNA sequence encoding a new type of scorpion venom peptide (BmKAPi) was first isolated from the venom gland of Buthus martensii Karsch by cDNA library screening combined with 5'-race. The encoded precursor of BmKAPi consisted of 89 amino acid residues including a signal peptide of 24 residues, a putative mature peptide of 64 residues (BmKAPi) and an extra basic residue at the C-terminus which might be removed in the post-translational processing. BmKAPi is stabilized by five disulfide bridges, whereas all other disulfide-bridged scorpion toxins described are cross-linked by three or four disulfide bridges. It suggested the three-dimensional scaffold of BmKAPi might be different from other scorpion toxins. The amino acid sequence of BmKAPi showed no homology with other scorpion venom peptides, but shared a little similarity with some anticoagulant peptides and proteinase inhibitors isolated from hookworm, honeybee or European frog, respectively. RT-PCR analysis showed that BmKAPi mRNA could be induced by venom extraction suggesting BmKAPi might be a component of scorpion venom. These results suggest that BmKAPi is a new type of scorpion venom peptide different from other described scorpion toxins in structural and functional aspects.
Zeng
Xian-Chun
XC
Department of Biotechnology, Institute of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China. zengx@nhlbi.nih.gov
Wang
San-Xia
SX
Li
Wen-Xin
WX
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D004220:Disulfides / Q000737:chemistry; D015723:Gene Library; D008969:Molecular Sequence Data; D010455:Peptides / Q000302:isolation & purification*; D012333:RNA, Messenger; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012604:Scorpion Venoms / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D012605:Scorpions / Q000502:physiology*; D017422:Sequence Analysis, DNA
D018076:DNA, Complementary; D004220:Disulfides; C472508:KAPi toxin, Buthus martensii; D010455:Peptides; D012333:RNA, Messenger; D012604:Scorpion Venoms