Murine startle mutant Nmf11 affects the structural stability of the glycine receptor and increases deactivation

M E Wilkins; A Caley; M C Gielen; Robert J Harvey; T G Smart

doi:10.1113/JP272122

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Murine startle mutant Nmf11 affects the structural stability of the glycine receptor and increases deactivation

Journal article

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Murine startle mutant Nmf11 affects the structural stability of the glycine receptor and increases deactivation

M E Wilkins, A Caley, M C Gielen, Robert J Harvey and T G Smart

Journal of Physiology, Vol.594(13), pp.3589-3607

2016

DOI: https://doi.org/10.1113/JP272122

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Abstract

Dysfunctional glycinergic inhibitory transmission underlies the debilitating neuro-logical condition, hyperekplexia, which is characterised by exaggerated startle reflexes, muscle hypertonia and apnoea. Here we investigated the N46K missense mutation in the GlyR α1 subunitgene found in the ethylnitrosourea (ENU) murine mutant, Nmf11, which causes reduced body size, evoked tremor, seizures, muscle stiffness, and morbidity by postnatal day 21. Introducing the N46K mutation into recombinant GlyR α1 homomeric receptors, expressed in HEK cells,reduced the potencies of glycine, β-alanine and taurine by 9-, 6- and 3-fold respectively, and that of the competitive antagonist strychnine by 15-fold. Replacing N46 with hydrophobic, charged or polar residues revealed that the amide moiety of asparagine was crucial for GlyR activation.Co-mutating N61, located on a neighbouring β loop to N46, rescued the wild-type phenotype depending on the amino acid charge. Single-channel recording identiï¬ed that burst length for the N46K mutant was reduced and fast agonist application revealed faster glycine deactivation times for the N46K mutant compared with the WT receptor. Overall, these data are consistent with N46 ensuring correct alignment of the α1 subunit interface by interaction with juxtaposed residues top reserve the structural integrity of the glycine binding site. This represents a new mechanism by which GlyR dysfunction induces startle disease.

Details

Title: Murine startle mutant Nmf11 affects the structural stability of the glycine receptor and increases deactivation
Authors: M E Wilkins (Author) - University College London, United Kingdom
A Caley (Author) - University College London, United Kingdom
M C Gielen (Author) - University College London, United Kingdom
Robert J Harvey (Author) - UCL School of Pharmacy, United Kingdom
T G Smart (Author) - University College London, United Kingdom
Publication details: Journal of Physiology, Vol.594(13), pp.3589-3607
Publisher: Wiley-Blackwell Publishing Ltd.
Date published: 2016
DOI: 10.1113/JP272122
ISSN: 0022-3751
Copyright note: Copyright © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distributionand reproduction in any medium, provided the original work is properly cited.
Organisation Unit: School of Health; University of the Sunshine Coast, Queensland; School of Health and Sport Sciences - Legacy; Centre for Bioinnovation; School of Health and Behavioural Sciences - Legacy
Language: English
Record Identifier: 99451094402621
Output Type: Journal article

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