Molecular diversification of peptide toxins from the tarantula Haplopelma hainanum (Ornithoctonus hainana) venom based on transcriptomic, peptidomic, and genomic analyses.

The tarantula Haplopelma hainanum (Ornithoctonus hainana) is a very venomous spider found widely in the hilly areas of Hainan province in southern China. Its venom contains a variety of toxic components with different pharmacological properties. In the present study, we used a venomic strategy for high-throughput identification of tarantula-venom peptides from H. hainanum. This strategy includes three different approaches: (i) transcriptomics, that is, EST-based cloning and PCR-based cloning plus DNA sequencing; (ii) peptidomics, that is, off-line multiple dimensional liquid chromatography coupled with mass spectrometry (MDLC-MS) plus peptide sequencing (direct Edman sequencing and bottom-up mass spectrometric sequencing); (iii) genomics, that is, genomic DNA cloning plus DNA sequencing. About 420 peptide toxins were detected by mass spectrometry, and 272 peptide precursors were deduced from cDNA and genomic DNA sequences. After redundancy removal, 192 mature sequences were identified by three approaches. This is the largest number of peptide toxin sequences identified from a spider species so far. On the basis of precursor sequence identity, peptide toxins from the tarantula H. hainanum venom can be classified into 11 superfamilies (and related families). Our results revealed that gene duplication and focal hypermutation may be responsible for the enormous molecular diversity in spider peptide toxins. The current work is an initial overview for the study of tarantula-venom peptides in parallel transcriptomic, peptidomic, and genomic analyses. It is hoped that this work will also provide an effective guide for high-throughput identification of peptide toxins from other spider species, especially tarantula species.