Effects and mechanism of Chinese tarantula toxins on the Kv2.1 potassium channels.
Three neurotoxins, Jingzhaotoxin-I, -III, and -V (JZTX-I, -III, and -V), isolated from the venom of the Chinese tarantula Chilobrachys Jingzhao, are 29-36-amino acid peptides. Electrophysiological recordings carried out in Xenopus laevis oocytes show that these toxins acted as gating modifier of voltage-dependent K+ channels. They slow the rate of Kv2.1 channel activation and increase the tail current deactivation, suggesting that toxin-bound channels can still open but are modified. JZTX-III selectively inhibits Kv2.1 channels, and JZTX-V exhibits a higher affinity to Kv4.2 channels than to Kv2.1 channels, whereas JZTX-I inhibits Kv2.1 and Kv4.1 channels with low affinity. Structure-function analysis indicates that electrostatic interactions can benefit for toxin affinity and the feature of electrostatic anisotropy may be correlated with the different affinity of the toxins for the Kv2.1 and Kv4.1 channels. Furthermore, phylogenetic analysis of these and other gating modifiers provides clues for the exploration of toxin-channel interaction.
Yuan
Chunhua
C
The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, Life Science College, Hunan Normal University, Changsha 410081, PR China.
Yang
Shengqing
S
Liao
Zhi
Z
Liang
Songping
S
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D051669:Shab Potassium Channels / Q000187:drug effects* / Q000502:physiology*; D013111:Spider Venoms / Q000008:administration & dosage*; D014982:Xenopus laevis
D051669:Shab Potassium Channels; D013111:Spider Venoms