title: Molecular determinants for the tarantula toxin jingzhaotoxin-I interacting with potassium channel Kv2.1.
abstract: With high binding affinity and distinct pharmacological functions, animal toxins are powerful ligands to investigate the structure-function relationships of voltage-gated ion channels. Jingzhaotoxin-I (JZTX-I) is an important neurotoxin from the tarantula Chilobrachys jingzhao venom that inhibits both sodium and potassium channels. In our previous work, JZTX-I, as a gating modifier, is able to inhibit activation of the potassium channel subtype Kv2.1. However, its binding site on Kv2.1 remains unknown. In this study, using Ala-scanning mutagenesis strategy, we demonstrated that four residues (I273, F274, E277, and K280) in S3b-S4 motif contributed to the formation of JZTX-I binding site. The mutations I273A, F274A, E277A, and K280A reduced toxin binding affinity by 6-, 10-, 8-, and 7-fold, respectively. Taken together with our previous data that JZTX-I accelerated channel deactivation, these results suggest that JZTX-I inhibits Kv2.1 activation by docking onto the voltage sensor paddle and trapping the voltage sensor in the closed state.
authors.affiliation: Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha, Hunan 410081, China.
authors.forename: Huai
authors.initials: H
authors.lastname: Tao
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wu
authors.forename: Meichun
authors.initials: M
authors.lastname: Deng
authors.forename: Juan
authors.initials: J
authors.lastname: He
authors.forename: Meichi
authors.initials: M
authors.lastname: Wang
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Xiao
authors.forename: Songping
authors.initials: S
authors.lastname: Liang
mesh_terms: D000409:Alanine / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000235:genetics; D004553:Electric Conductivity; D005260:Female; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D008958:Models, Molecular; D016296:Mutagenesis; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D017354:Point Mutation; D011485:Protein Binding; D012315:RNA Caps / Q000494:pharmacology; D051669:Shab Potassium Channels / Q000235:genetics / Q000378:metabolism*; D013111:Spider Venoms / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D013112:Spiders; D014982:Xenopus laevis
chemical_list: D010455:Peptides; D012315:RNA Caps; D051669:Shab Potassium Channels; D013111:Spider Venoms; C500354:jingzhaotoxin-I, Chilobrachys jingzhao; D000409:Alanine