Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus

Rajendra Wudayagiri¹^,2 , Bora Inceoglu² , Rafael Herrmann³ , Maher Derbel² , Prabhakara V Choudary⁴ and Bruce D Hammock²

¹Department of Zoology, Sri Venkateswara University, Tirupati – 517 502, India

²Department of Entomology, University of California, Davis, CA 95616, USA

³DuPont Agricultural Products, Stine-Haskel Research Center, P.O. Box 30, Elkton Road, Newark, DE 19714, USA

⁴Division of Biological Sciences, University of California, Davis, CA 95616, USA

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BMC Biochemistry 2001, 2:16doi:10.1186/1471-2091-2-16


Published:	17 December 2001

Abstract

Background

Scorpion venom contains insect and mammal selective toxins. We investigated the venom of the South Indian red scorpion, Mesobuthus tamulus for the purpose of identifying potent insecticidal peptide toxins.

Results

A lepidopteran-selective toxin (Buthus tamulus insect toxin; ButaIT) has been isolated from this venom. The primary structure analysis reveals that it is a single polypeptide composed of 37 amino acids cross-linked by four disulfide bridges with high sequence homology to other short toxins such as Peptide I, neurotoxin P2, Lqh-8/6, chlorotoxin, insectotoxin I5A, insect toxin 15 and insectotoxin I1. Three dimensional modeling using Swiss automated protein modeling server reveals that this toxin contains a short α-helix and three antiparallel β-strands, similar to other short scorpion toxins. This toxin is selectively active on Heliothis virescens causing flaccid paralysis but was non-toxic to blowfly larvae and mice.

Conclusion

This is the first report of a Heliothine selective peptide toxin. Identification of diverse insect selective toxins offer advantages in employing these peptides selectively for pest control.