The pore domain outer helix contributes to both activation and inactivation of the HERG K+ channel

Pengchu Ju, Guilhem Pages, R. Peter Riek, Pochia Chen, Allan M. Torres, Paramjit S. Bansal, Serdar Kuyucak, Philip W. Kuchel, Jamie I. Vandenberg

    Research output: Contribution to journalArticle

    44 Citations (Scopus)

    Abstract

    Ion flow in many voltage-gated K(+) channels (VGK), including the (human ether-a-go-go-related gene) hERG channel, is regulated by reversible collapse of the selectivity filter. hERG channels, however, exhibit low sequence homology to other VGKs, particularly in the outer pore helix (S5) domain, and we hypothesize that this contributes to the unique activation and inactivation kinetics in hERG K(+) channels that are so important for cardiac electrical activity. The S5 domain in hERG identified by NMR spectroscopy closely corresponded to the segment predicted by bioinformatics analysis of 676 members of the VGK superfamily. Mutations to approximately every third residue, from Phe(551) to Trp(563), affected steady state activation, whereas mutations to approximately every third residue on an adjacent face and spanning the entire S5 segment perturbed inactivation, suggesting that the whole span of S5 experiences a rearrangement associated with inactivation. We refined a homology model of the hERG pore domain using constraints from the mutagenesis data with residues affecting inactivation pointing in toward S6. In this model the three residues with maximum impact on activation (W563A, F559A, and F551A) face out toward the voltage sensor. In addition, the residues that when mutated to alanine, or from alanine to valine, that did not express (Ala(561), His(562), Ala(565), Trp(568), and Ile(571)), all point toward the pore helix and contribute to close hydrophobic packing in this region of the channel.
    Original languageEnglish
    Pages (from-to)1000-1008
    Number of pages9
    JournalJournal of Biological Chemistry
    Volume284
    Issue number2
    DOIs
    Publication statusPublished - 2009

    Keywords

    • HERG K+ channel
    • alanine
    • amino acids
    • ion channels
    • nuclear magnetic resonance spectroscopy
    • valine

    Fingerprint

    Dive into the research topics of 'The pore domain outer helix contributes to both activation and inactivation of the HERG K+ channel'. Together they form a unique fingerprint.

    Cite this