Kuhn-Nentwig L, Schaller J, Kämpfer U, Imboden H, Malli H, Nentwig W
Institute of Zoology, University of Bern, Switzerland.
Arch Insect Biochem Physiol. 2000 Jul;44(3):101-11. doi: 10.1002/1520-6327(200007)44:3<101::AID-ARCH1>3.0.CO;2-S.
CSTX-1 (74 amino acids, 8,352.62 Da) is a potent neurotoxin from the venom of Cupiennius salei. With the monoclonal antibody 9H3 against CSTX-1, we identified two similar peptides by Western blot analysis. These two peptides were purified by RP-HPLC: CSTX-2a (61 amino acids, 6865.75 Da) and CSTX-2b (60 amino acids, 6709.57 Da). Using ESI-MS analysis and sequencing we verified that CSTX-2a is a truncated version of CSTX-1. CSTX-2b differs from CSTX-2a by the absence of Arg61. Toxicity of CSTX-1, CSTX-2a, and CSTX-2b to Drosophila melanogaster showed that the absence of the last 13 amino acids of CSTX-1 results in a seven-fold activity loss. CSTX-2b, which lacks Arg61 is 190-fold less toxic. We conclude that the C-terminal part of CSTX-1, especially Arg61, is essential for the expression of toxicity. CSTX-1 is degraded to CSTX-2a and CSTX-2b by proteases that are released from venom gland cells by apocrine secretion.
CSTX-1（74个氨基酸，8352.62道尔顿）是一种来自智利游走蛛毒液的强效神经毒素。利用抗CSTX-1的单克隆抗体9H3，我们通过蛋白质印迹分析鉴定出了两种相似的肽段。这两种肽段通过反相高效液相色谱法（RP-HPLC）进行了纯化：CSTX-2a（61个氨基酸，6865.75道尔顿）和CSTX-2b（60个氨基酸，6709.57道尔顿）。通过电喷雾电离质谱分析（ESI-MS）和测序，我们证实CSTX-2a是CSTX-1的截短版本。CSTX-2b与CSTX-2a的不同之处在于缺少精氨酸61。CSTX-1、CSTX-2a和CSTX-2b对黑腹果蝇的毒性表明，CSTX-1缺失最后13个氨基酸会导致活性损失7倍。缺少精氨酸61的CSTX-2b毒性低190倍。我们得出结论，CSTX-1的C末端部分，尤其是精氨酸61，对毒性表达至关重要。CSTX-1通过顶浆分泌从毒腺细胞释放的蛋白酶降解为CSTX-2a和CSTX-2b。
