Isolation of an orally active insecticidal toxin from the venom of an Australian tarantula (Table S1)

We isolated a 34-residue orally active insecticidal peptide (OAIP-1) from venom of the Australian tarantula Selenotypus plumipes. The oral LD50 for OAIP-1 in the agronomically important cotton bollworm Helicoverpa armigera was 104.2±0.6 pmol/g, which is the highest per os activity reported to date for an insecticidal venom peptide. OAIP-1 is equipotent with synthetic pyrethroids and it acts synergistically with neonicotinoid insecticides. The three-dimensional structure of OAIP-1 determined using NMR spectroscopy revealed that the three disulfide bonds form an inhibitor cystine knot motif; this structural motif provides the peptide with a high level of biological stability that probably contributes to its oral activity. OAIP-1 is likely to be synergized by the gut-lytic activity of the Bacillus thuringiensis Cry toxin (Bt) expressed in insect-resistant transgenic crops, and consequently it might be a good candidate for trait stacking with Bt.

我们从澳大利亚捕鸟蛛（Selenotypus plumipes）的毒液中分离得到一种含34个氨基酸残基的口服活性杀虫肽（orally active insecticidal peptide，OAIP-1）。该肽对农业生产中具有重要经济价值的棉铃虫（Helicoverpa armigera）的经口半数致死剂量为104.2±0.6 pmol/g，是目前已报道的杀虫毒液肽中经口活性最高的组分。OAIP-1的杀虫效价与合成拟除虫菊酯类杀虫剂相当，且可与新烟碱类杀虫剂产生协同作用。通过核磁共振波谱法（NMR spectroscopy）解析得到的OAIP-1三维结构显示，其三个二硫键形成了抑制剂胱氨酸结模体（inhibitor cystine knot motif）；该结构模体赋予该肽极高的生物学稳定性，这大概率是其具备口服活性的关键原因。抗虫转基因作物中表达的苏云金杆菌Cry毒素（Bacillus thuringiensis Cry toxin，Bt）的肠道裂解活性，或可协同增强OAIP-1的杀虫效果，因此OAIP-1有望成为与Bt性状堆叠（trait stacking）的优良候选材料。