Wei Peng, Xu Changxi, Wu Qiaoqi, Huang Lang, Liang Songping, Yuan Chunhua
Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, Southern Medical University, Guangzhou 510515, China.
Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China.
Toxicon. 2014 Dec 15;92:90-6. doi: 10.1016/j.toxicon.2014.10.008. Epub 2014 Oct 15.
Jingzhaotoxin-35 (JZTX-35), a 36-residue polypeptide, was purified from the venom of the Chinese tarantula Chilobrachys jingzhao. JZTX-35 inhibited Nav1.5 and Kv2.1 currents with the IC50 value of 1.07 μM and 3.62 μM, respectively, but showed no significant effect on either Na(+) currents or Ca(2+) currents evoked in hippocampal neurons. It shifted the activation of the Nav1.5 and Kv2.1 channels to more depolarized voltages, and markedly shifted the steady-state inactivation of Nav1.5 currents toward more hyperpolarized potentials. Moreover, JZTX-35 can bind to a close state of Nav1.5 and Kv2.1 channels. These results indicate that JZTX-35 is a new gating modifier toxin. JZTX-35 shares high sequence similarity with Jingzhaotoxins (JZTXs) targeting Nav1.5 or Kv2.1 channels, but they showed different ion channel selectivity. Structure-function analysis in this study would provide important clues for the exploration of ion channel selectivity of JZTXs.
敬钊毒素-35（JZTX-35）是一种由36个氨基酸残基组成的多肽，从中国捕鸟蛛敬钊缨毛蛛的毒液中纯化得到。JZTX-35对Nav1.5和Kv2.1电流具有抑制作用，其IC50值分别为1.07 μM和3.62 μM，但对海马神经元中诱发的Na⁺电流或Ca²⁺电流均无显著影响。它使Nav1.5和Kv2.1通道的激活向更去极化的电压方向移动，并使Nav1.5电流的稳态失活明显向更超极化的电位方向移动。此外，JZTX-35可与Nav1.5和Kv2.1通道的关闭状态结合。这些结果表明JZTX-35是一种新型的门控修饰毒素。JZTX-35与靶向Nav1.5或Kv2.1通道的敬钊毒素（JZTXs）具有高度的序列相似性，但它们表现出不同的离子通道选择性。本研究中的结构-功能分析将为探索JZTXs的离子通道选择性提供重要线索。
