C-terminal β9-strand of the cyclic nucleotide-binding homology domain stabilizes activated states of Kv11.1 channels

Chai Ann Ng; Ying Ke; Matthew D Perry; Peter S Tan; Adam P Hill; Jamie I Vandenberg

doi:10.1371/journal.pone.0077032

C-terminal β9-strand of the cyclic nucleotide-binding homology domain stabilizes activated states of Kv11.1 channels

PLoS One. 2013 Oct 25;8(10):e77032. doi: 10.1371/journal.pone.0077032. eCollection 2013.

Authors

Chai Ann Ng¹, Ying Ke, Matthew D Perry, Peter S Tan, Adam P Hill, Jamie I Vandenberg

Affiliation

¹ Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia ; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia.

Abstract

Kv11.1 potassium channels are important for regulation of the normal rhythm of the heartbeat. Reduced activity of Kv11.1 channels causes long QT syndrome type 2, a disorder that increases the risk of cardiac arrhythmias and sudden cardiac arrest. Kv11.1 channels are members of the KCNH subfamily of voltage-gated K(+) channels. However, they also share many similarities with the cyclic nucleotide gated ion channel family, including having a cyclic nucleotide-binding homology (cNBH) domain. Kv11.1 channels, however, are not directly regulated by cyclic nucleotides. Recently, crystal structures of the cNBH domain from mEAG and zELK channels, both members of the KCNH family of voltage-gated potassium channels, revealed that a C-terminal β9-strand in the cNBH domain occupied the putative cyclic nucleotide-binding site thereby precluding binding of cyclic nucleotides. Here we show that mutations to residues in the β9-strand affect the stability of the open state relative to the closed state of Kv11.1 channels. We also show that disrupting the structure of the β9-strand reduces the stability of the inactivated state relative to the open state. Clinical mutations located in this β9-strand result in reduced trafficking efficiency, which suggests that binding of the C-terminal β9-strand to the putative cyclic nucleotide-binding pocket is also important for assembly and trafficking of Kv11.1 channels.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amino Acid Sequence
Animals
Binding Sites / genetics
ERG1 Potassium Channel
Ether-A-Go-Go Potassium Channels / chemistry*
Ether-A-Go-Go Potassium Channels / genetics*
Ether-A-Go-Go Potassium Channels / metabolism
Female
HEK293 Cells
Humans
Hydrogen Bonding
Ion Channel Gating / genetics
Ion Channel Gating / physiology
Long QT Syndrome / genetics
Long QT Syndrome / physiopathology
Models, Molecular
Molecular Dynamics Simulation
Molecular Sequence Data
Mutation*
Nucleotides, Cyclic / chemistry*
Nucleotides, Cyclic / metabolism
Oocytes / metabolism
Oocytes / physiology
Protein Binding
Protein Structure, Secondary
Protein Structure, Tertiary*
Sequence Homology, Amino Acid
Xenopus laevis

Substances

ERG1 Potassium Channel
Ether-A-Go-Go Potassium Channels
KCNH2 protein, human
Nucleotides, Cyclic

Supplementary concepts

Long Qt Syndrome 2

Grants and funding

This work was supported by grants from the National Health and Medical Research Council of Australia (#573715) (www.nhmrc.gov.au) and the National Heart Foundation of Australia (#G11S5829) (www.heartfoundation.org.au). JIV is supported by an NHMRC Senior Research Fellowship (#1019693) (www.nhmrc.gov.au) and APH is supported by an Australian Research Council Future Fellowship (FT110100075) (www.arc.gov.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.