Identification, classification and characterization of the dermonecrotic toxins in venom glands of Hottentotta saulcyi, Androctonus crassicauda and Hemiscorpius lepturus using transcriptome analysis

Abstract

Abstract Venom phospholipase D (PLDs), known as dermonecrotic toxins, are the major molecules in the crude venom of scorpions that are mainly responsible for lethality and dermonecrotic lesions during scorpion envenoming. The purpose of this study was fourfold: First to identify transcripts coding for venom dermonecrotic toxin by transcriptomic analysis of the venom from Androctonus crassicauda, Hottentotta saulcyi, and Hemiscorpius lepturus; second to classify them by sequence similarity to known PLDs and motif extraction method; third to characterize scorpion PLDs; and fourth to investigate phylogenetic relationships of the PLD proteins. This is the first report of the presence of dermonecrotic toxin sequence in A. crassicauda and H. saulcyi venom. We found that the venom gland of scorpions encodes two PLD isoforms; PLD1 ScoTox-beta and PLD2 ScoTox-alpha I. Two highly conserved regions shared by all PLDs beta are GAN and HPCDC (HX2PCDC), and the most important conserved regions shared by all PLDs alpha are two copies of the HKDG (HxKx4Dx6G) motif. We found that PLD1 is a 31–43 kDa acidic protein containing signal sequences and PLD2 is a 128 kDa basic protein without known signal sequences. The gene structures of PLD1 and PLD2 contain 6 and 21 exons respectively.