Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel NaV1.2

Liam Hovey; C. Andrew Fowler; Ryan Mahling; Zesen Lin; Mark Stephen Miller; Dagan C Marx; Jesse B Yoder; Elaine H Kim; Kristin M Tefft; Brett C Waite; Michael D Feldkamp; Liping Yu; Madeline A Shea

doi:10.1016/j.bpc.2017.02.006

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Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel NaV1.2

Journal article

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Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel NaV1.2

Liam Hovey, C. Andrew Fowler, Ryan Mahling, Zesen Lin, Mark Stephen Miller, Dagan C Marx, Jesse B Yoder, Elaine H Kim, Kristin M Tefft, Brett C Waite, …

Biophysical chemistry, Vol.224, pp.1-19

05/2017

DOI: 10.1016/j.bpc.2017.02.006

PMCID: PMC5503752

PMID: 28343066

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Abstract

Several members of the voltage-gated sodium channel family are regulated by calmodulin (CaM) and ionic calcium. The neuronal voltage-gated sodium channel NaV1.2 contains binding sites for both apo (calcium-depleted) and calcium-saturated CaM. We have determined equilibrium dissociation constants for rat NaV1.2 IQ motif [IQRAYRRYLLK] binding to apo CaM (~3nM) and (Ca2+)4-CaM (~85nM), showing that apo CaM binding is favored by 30-fold. For both apo and (Ca2+)4-CaM, NMR demonstrated that NaV1.2 IQ motif peptide (NaV1.2IQp) exclusively made contacts with C-domain residues of CaM (CaMC). To understand how calcium triggers conformational change at the CaM-IQ interface, we determined a solution structure (2M5E.pdb) of (Ca2+)2-CaMC bound to NaV1.2IQp. The polarity of (Ca2+)2-CaMC relative to the IQ motif was opposite to that seen in apo CaMC-Nav1.2IQp (2KXW), revealing that CaMC recognizes nested, anti-parallel sites in Nav1.2IQp. Reversal of CaM may require transient release from the IQ motif during calcium binding, and facilitate a re-orientation of CaMN allowing interactions with non-IQ NaV1.2 residues or auxiliary regulatory proteins interacting in the vicinity of the IQ motif. [Display omitted] •NaV1.2 IQ motif binds apo and (Ca2+)4-CaM tightly: how can Ca2+ binding trigger change?•Direct measure of equilibrium Kd values: apo CaM (~3nM) vs. (Ca2+)4-CaM (~85nM)•Solution structure of (Ca2+)2-CaMC bound to NaV1.2 IQ has “open” EF-hand conformation.•2KXW and 2M5E are first NMR structures of apo and Ca2+-CaMC bound to same channel.•CaM binds nested, anti-parallel sites in NaV1.2 IQ; Ca2+ binding to CaMC reverses its orientation.

Molecular Recognition

Thermodynamics

Binding

Sodium channels

NMR

Linkage

Biosensor

Allostery

Titration

FRET

Free energy

Details

Title: Subtitle: Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel NaV1.2
Creators: Liam Hovey - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
C. Andrew Fowler - NMR Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242-1109 Iowa City, United States
Ryan Mahling - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Zesen Lin - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Mark Stephen Miller - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Dagan C Marx - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Jesse B Yoder - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Elaine H Kim - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Kristin M Tefft - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Brett C Waite - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Michael D Feldkamp - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Liping Yu - NMR Facility, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 52242-1109 Iowa City, United States
Madeline A Shea - Department of Biochemistry, University of Iowa, 52242-1109 Iowa City, United States
Resource Type: Journal article
Publication Details: Biophysical chemistry, Vol.224, pp.1-19
DOI: 10.1016/j.bpc.2017.02.006
PMID: 28343066
PMCID: PMC5503752
NLM abbreviation: Biophys Chem
ISSN: 0301-4622
eISSN: 1873-4200
Publisher: Elsevier B.V
Grant note: T32 GM08365; R01 GM57001 / National Institutes of Health 01-224 / Roy J. Carver Charitable Trust (http://dx.doi.org/10.13039/100001024) University of Iowa (http://dx.doi.org/10.13039/100008893)
Language: English
Date published: 05/2017
Academic Unit: Molecular Physiology and Biophysics; Iowa Neuroscience Institute; Biochemistry and Molecular Biology; Medicine Administration
Record Identifier: 9984024550902771

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