A novel amphipathic linear peptide with both insect toxicity and antimicrobial activity from the venom of the scorpion Isometrus maculatus.
Scorpion venoms are composed of a number of peptides, many of which show neurotoxicity. In addition to these neurotoxins, several antimicrobial peptides have also been isolated from the venoms. The scorpion Isometrus maculatus, belonging to the Buthidae family, is found in many tropical regions including Japan, but little attention has been paid to its biological activity and chemical composition. In this study, we isolated a novel insect toxin, Im-1, by bioassay-guided fractionation of the venom of I. maculatus. Rapid and reversible paralysis was observed after injection of Im-1 into crickets. Im-1 consists of 56 amino acids, and is predicted to form an amphipathic alpha-helix. Since Im-1 shares sequence similarity to an antimicrobial peptide, parabutoporin, we evaluated its effects on several bacterial strains and found that it showed an antimicrobial activity profile similar to parabutoporin. This suggests that Im-1 and parabutoporin exert their antimicrobial effects through similar mechanisms.
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Japan. miyamasa@kais.kyoto-u.ac.jp
Masahiro
M
Miyashita
Atsushi
A
Sakai
Nobuto
N
Matsushita
Yosuke
Y
Hanai
Yoshiaki
Y
Nakagawa
Hisashi
H
Miyagawa
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics; D000818:Animals; D000890:Anti-Infective Agents / Q000633:toxicity*; D007313:Insecta / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000633:toxicity; D010455:Peptides / Q000737:chemistry / Q000633:toxicity*; D017433:Protein Structure, Secondary / Q000235:genetics; D012604:Scorpion Venoms / Q000737:chemistry / Q000633:toxicity*; D012605:Scorpions / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D000596:Amino Acids; D000890:Anti-Infective Agents; D009498:Neurotoxins; D010455:Peptides; D012604:Scorpion Venoms