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Published on: March 12, 2013
Mechanisms of KCNQ1 gating modulation by KCNE1/3 for cell-specific function
Chenxi Cui1, Lu Zhao2, Ali A Kermani3
1Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
KCNE1 and KCNE3 subunits distinctly alter KCNQ1 potassium channel gating. KCNE3 creates a GPCR-regulated, voltage-insensitive channel, while KCNE1 forms a voltage-gated channel crucial for cardiac function.
Area of Science:
- Molecular Biology
- Biophysics
- Physiology
Background:
- KCNQ1 potassium channels are vital for heart rhythm and intestinal function.
- KCNE subunits (KCNE1-5) modify KCNQ1 channel properties.
- KCNQ1 gating depends on voltage and PIP2, influenced by GPCR signaling.
Purpose of the Study:
- To elucidate how KCNE1 and KCNE3 subunits modulate KCNQ1 channel gating.
- To investigate the structural basis for KCNE1/3 effects on KCNQ1's voltage and PIP2-dependent activation.
- To understand the distinct roles of KCNQ1-KCNE1 and KCNQ1-KCNE3 complexes in different cell types.
Main Methods:
- X-ray crystallography to resolve KCNQ1-KCNE1 complex structures.
- Reassessment of existing KCNQ1-KCNE3 structures with and without PIP2.
- Functional analysis of PIP2-dependent gating and GPCR modulation.
Main Results:
- KCNQ1-KCNE1/3 complexes possess two PIP2-binding sites, including a novel site involving voltage sensor-pore domain coupling residues.
- KCNE1 and KCNE3 differentially modulate KCNQ1's PIP2-dependent gating and voltage sensitivity.
- KCNE3 transforms KCNQ1 into a voltage-insensitive, PIP2-gated channel regulated by GPCRs.
- KCNE1 enhances KCNQ1's PIP2 affinity and GPCR resistance, forming voltage-gated channels for cardiac function.
Conclusions:
- KCNE1 and KCNE3 subunits impart distinct gating properties to KCNQ1 channels through unique structural interactions.
- KCNE3 enables GPCR-mediated regulation of KCNQ1 in non-excitable cells for ion homeostasis.
- KCNE1 promotes voltage-gated KCNQ1 function in cardiac cells, regulating the slow-delayed rectifier current.
- Understanding these KCNE1/3-KCNQ1 interactions offers insights for tissue-specific channel targeting.
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