6b8m

From Proteopedia

Crystal Structure of the Ca2+/CaM:Kv7.4 (KCNQ4) AB Domain Complex, 1 mM CaCl2 soak

PDB ID 6b8m

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Structural highlights

6b8m is a 8 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.3Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Disease

KCNQ4_HUMAN Defects in KCNQ4 are the cause of deafness autosomal dominant type 2A (DFNA2A) [MIM:600101. DFNA2A is a form of sensorineural hearing loss. Sensorineural deafness results from damage to the neural receptors of the inner ear, the nerve pathways to the brain, or the area of the brain that receives sound information.^[1] ^[2] ^[3] ^[4] ^[5]

Function

KCNQ4_HUMAN Probably important in the regulation of neuronal excitability. May underlie a potassium current involved in regulating the excitability of sensory cells of the cochlea. KCNQ4 channels are blocked by linopirdin, XE991 and bepridil, whereas clofilium is without significant effect. Muscarinic agonist oxotremorine-M strongly suppress KCNQ4 current in CHO cells in which cloned KCNQ4 channels were coexpressed with M1 muscarinic receptors.^[6]

Publication Abstract from PubMed

Kv7 (KCNQ) voltage-gated potassium channels control excitability in the brain, heart, and ear. Calmodulin (CaM) is crucial for Kv7 function, but how this calcium sensor affects activity has remained unclear. Here, we present X-ray crystallographic analysis of CaM:Kv7.4 and CaM:Kv7.5 AB domain complexes that reveal an Apo/CaM clamp conformation and calcium binding preferences. These structures, combined with small-angle X-ray scattering, biochemical, and functional studies, establish a regulatory mechanism for Kv7 CaM modulation based on a common architecture in which a CaM C-lobe calcium-dependent switch releases a shared Apo/CaM clamp conformation. This C-lobe switch inhibits voltage-dependent activation of Kv7.4 and Kv7.5 but facilitates Kv7.1, demonstrating that mechanism is shared by Kv7 isoforms despite the different directions of CaM modulation. Our findings provide a unified framework for understanding how CaM controls different Kv7 isoforms and highlight the role of membrane proximal domains for controlling voltage-gated channel function. VIDEO ABSTRACT.

A Calmodulin C-Lobe Ca(2+)-Dependent Switch Governs Kv7 Channel Function.,Chang A, Abderemane-Ali F, Hura GL, Rossen ND, Gate RE, Minor DL Jr. Neuron. 2018 Feb 21;97(4):836-852.e6. doi: 10.1016/j.neuron.2018.01.035. Epub, 2018 Feb 8. PMID:29429937^[7]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Kubisch C, Schroeder BC, Friedrich T, Lutjohann B, El-Amraoui A, Marlin S, Petit C, Jentsch TJ. KCNQ4, a novel potassium channel expressed in sensory outer hair cells, is mutated in dominant deafness. Cell. 1999 Feb 5;96(3):437-46. PMID:10025409
↑ Coucke PJ, Van Hauwe P, Kelley PM, Kunst H, Schatteman I, Van Velzen D, Meyers J, Ensink RJ, Verstreken M, Declau F, Marres H, Kastury K, Bhasin S, McGuirt WT, Smith RJ, Cremers CW, Van de Heyning P, Willems PJ, Smith SD, Van Camp G. Mutations in the KCNQ4 gene are responsible for autosomal dominant deafness in four DFNA2 families. Hum Mol Genet. 1999 Jul;8(7):1321-8. PMID:10369879
↑ Talebizadeh Z, Kelley PM, Askew JW, Beisel KW, Smith SD. Novel mutation in the KCNQ4 gene in a large kindred with dominant progressive hearing loss. Hum Mutat. 1999;14(6):493-501. PMID:10571947 doi:<493::AID-HUMU8>3.0.CO;2-P 10.1002/(SICI)1098-1004(199912)14:6<493::AID-HUMU8>3.0.CO;2-P
↑ Van Hauwe P, Coucke PJ, Ensink RJ, Huygen P, Cremers CW, Van Camp G. Mutations in the KCNQ4 K+ channel gene, responsible for autosomal dominant hearing loss, cluster in the channel pore region. Am J Med Genet. 2000 Jul 31;93(3):184-7. PMID:10925378
↑ Arnett J, Emery SB, Kim TB, Boerst AK, Lee K, Leal SM, Lesperance MM. Autosomal dominant progressive sensorineural hearing loss due to a novel mutation in the KCNQ4 gene. Arch Otolaryngol Head Neck Surg. 2011 Jan;137(1):54-9. doi:, 10.1001/archoto.2010.234. PMID:21242547 doi:10.1001/archoto.2010.234
↑ Sogaard R, Ljungstrom T, Pedersen KA, Olesen SP, Jensen BS. KCNQ4 channels expressed in mammalian cells: functional characteristics and pharmacology. Am J Physiol Cell Physiol. 2001 Apr;280(4):C859-66. PMID:11245603
↑ Chang A, Abderemane-Ali F, Hura GL, Rossen ND, Gate RE, Minor DL Jr.. A Calmodulin C-Lobe Ca(2+)-Dependent Switch Governs Kv7 Channel Function. Neuron. 2018 Feb 21;97(4):836-852.e6. doi: 10.1016/j.neuron.2018.01.035. Epub, 2018 Feb 8. PMID:29429937 doi:http://dx.doi.org/10.1016/j.neuron.2018.01.035