Referenced in: none

Automatically associated channels: Kv7.1 , Slo1

Title: A distinct three-helix centipede toxin SSD609 inhibits I(ks) channels by interacting with the KCNE1 auxiliary subunit.

Authors: Peibei Sun, Fangming Wu, Ming Wen, Xingwang Yang, Chenyang Wang, Yiming Li, Shufang He, Longhua Zhang, Yun Zhang, Changlin Tian

Journal, date & volume: Sci Rep, 2015 , 5, 13399

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/26307551

Abstract
KCNE1 is a single-span transmembrane auxiliary protein that modulates the voltage-gated potassium channel KCNQ1. The KCNQ1/KCNE1 complex in cardiomyocytes exhibited slow activated potassium (I(ks)) currents. Recently, a novel 47-residue polypeptide toxin SSD609 was purified from Scolopendra subspinipes dehaani venom and showed I(ks) current inhibition. Here, chemically synthesized SSD609 was shown to exert I(ks) inhibition in extracted guinea pig cardiomyocytes and KCNQ1/KCNE1 current attenuation in CHO cells. The K(+) current attenuation of SSD609 showed decent selectivity among different auxiliary subunits. Solution nuclear magnetic resonance analysis of SSD609 revealed a distinctive three-helix conformation that was stabilized by a new disulfide bonding pattern as well as segregated surface charge distribution. Structure-activity studies demonstrated that negatively charged Glu19 in the amphipathic extracellular helix of KCNE1 was the key residue that interacted with SSD609. The distinctive three-helix centipede toxin SSD609 is known to be the first polypeptide toxin acting on channel auxiliary subunit KCNE1, which suggests a new type of pharmacological regulation for ion channels in cardiomyocytes.