This Article Full Text Full Text (PDF) Supplement All Versions of this Article: biophysj.106.097360v1 92/10/3524    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tseng, G.-N. Articles by Guy, H. R. Search for Related Content PubMed PubMed Citation Articles by Tseng, G.-N. Articles by Guy, H. R.

Probing the Outer Mouth Structure of the hERG Channel with Peptide Toxin Footprinting and Molecular Modeling

Gea-Ny Tseng ^*, Kailas D. Sonawane , Yuliya V. Korolkova , Mei Zhang ^*, Jie Liu ^*, Eugene V. Grishin  and H. Robert Guy 

^* Department of Physiology, Virginia Commonwealth University, Richmond, Virginia; Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland; and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia

Correspondence: Address reprint requests to Gea-Ny Tseng, PhD, Dept. of Physiology, Virginia Commonwealth University, 1101 E. Marshall St., Richmond, VA 23298. Tel.: 804-827-0811; Fax: 804-828-7382; E-mail: gtseng{at}vcu.edu.

Previous studies have shown that the unusually long S5-P linker lining human ether a-go-go related gene's (hERG's) outer vestibule is critical for its channel function: point mutations at high-impact positions here can interfere with the inactivation process and, in many cases, also reduce the pore's K⁺ selectivity. Because no data are available on the equivalent region in the available K channel crystal structures to allow for homology modeling, we used alternative approaches to model its three-dimensional structure. The first part of this article describes mutant cycle analysis used to identify residues on hERG's outer vestibule that interact with specific residues on the interaction surface of BeKm-1, a peptide toxin with known NMR structure and a high binding affinity to hERG. The second part describes molecular modeling of hERG's pore domain. The transmembrane region was modeled after the crystal structure of KvAP pore domain. The S5-P linker was docked to the transmembrane region based on data from previous NMR and mutagenesis experiments, as well as a set of modeling criteria. The models were further restrained by contact points between hERG's outer vestibule and the bound BeKm-1 toxin molecule deduced from the mutant cycle analysis. Based on these analyses, we propose a working model for the open conformation of the outer vestibule of the hERG channel, in which the S5-P linkers interact with the pore loops to influence ion flux through the pore.

This article has been cited by other articles:

				X. Xu, M. Recanatini, M. Roberti, and G.-N. Tseng Probing the Binding Sites and Mechanisms of Action of Two Human Ether-a-go-go-Related Gene Channel Activators, 1,3-bis-(2-Hydroxy-5-trifluoromethyl-phenyl)-urea (NS1643) and 2-[2-(3,4-Dichloro-phenyl)-2,3-dihydro-1H-isoindol-5-ylamino]-nicotinic acid (PD307243) Mol. Pharmacol., June 1, 2008; 73(6): 1709 - 1721. [Abstract] [Full Text] [PDF]

				E. Gordon, I. M. Lozinskaya, Z. Lin, S. F. Semus, F. E. Blaney, R. N. Willette, and X. Xu 2-[2-(3,4-Dichloro-phenyl)-2,3-dihydro-1H-isoindol-5-ylamino]-nicotinic Acid (PD-307243) Causes Instantaneous Current through Human Ether-a-go-go-Related Gene Potassium Channels Mol. Pharmacol., March 1, 2008; 73(3): 639 - 651. [Abstract] [Full Text] [PDF]

				M. Zhang, X.-S. Liu, S. Diochot, M. Lazdunski, and G.-N. Tseng APETx1 from Sea Anemone Anthopleura elegantissima Is a Gating Modifier Peptide Toxin of the Human Ether-a-go-go- Related Potassium Channel Mol. Pharmacol., August 1, 2007; 72(2): 259 - 268. [Abstract] [Full Text] [PDF]