[3P-1] Poster 3 (3P-01ー3P-47)

[3P-20] Mechanism of hERG inhibition by gating-modifier toxin, APETx1, deduced by functional characterization

Kazuki Matsumura¹, Takushi Shimomura², Yoshihiro Kubo², Takayuki Oka³, Naohiro Kobayashi^4,5, Shunsuke Imai⁶, Naomi Yanase¹, Madoka Akimoto¹, Masahiro Fukuda¹, Mariko Yokogawa¹, Kazuyoshi Ikeda¹, Jun-ichi Kurita⁷, Yoshifumi Nishimura⁷, Ichio Shimada⁶, ^○Masanori Osawa¹ (1.Grad. Sch. Pharm. Sci., Keio Univ., 2.Dept. Mol. Cell. Physiol., NIPS, 3.Nanion Technologies Japan, 4.IPR, Osaka Univ., 5.RSC, RIKEN, 6.Grad. Sch. Pharm. Sci., Univ. of Tokyo, 7.Grad. Sch. Med. Life Sci., Yokohama City Univ.)

Human ether-a-go-go-related gene potassium channel 1 (hERG) is a voltage-gated potassium channel, the voltage-sensing domain (VSD) of which is targeted by a gating-modifier toxin, APETx1. APETx1 is a 42-residue peptide toxin of Anthopleura elegantissima and inhibits hERG by stabilizing the resting state. Mutational analysis of APETx1 could not be conducted as only natural resources have been available until now. Therefore, it remains unclear where and how APETx1 interacts with the VSD in the resting state. We established a method for preparing recombinant APETx1 and determined the NMR structure of the recombinant APETx1, which is structurally equivalent to the natural product. Electrophysiological analyses using wild type and mutants of APETx1 and hERG revealed that F15, Y32, F33, and L34 in APETx1, and F508 and I521 in hERG, in addition to E518, play key roles in hERG inhibition by APETx1. Our hypothetical docking models of the APETx1-VSD complex are consistent to the results of mutational analysis. These results would help advance understanding of the inhibitory mechanism of APETx1, which could provide a structural basis for designing novel ligands targeting the VSDs of hERG.