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Structure, dynamics, and ligand recognition of human-specific chrfam7a (Dupα7) nicotinic receptor linked to neuropsychiatric disorders

Lookup NU author(s): Danlin Liu, Ayaz Ahmad, Dr Agnieszka Bronowska

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2021 by the authors. Licensee MDPI, Basel, Switzerland.Cholinergic α7 nicotinic receptors encoded by the CHRNA7 gene are ligand-gated ion channels directly related to memory and immunomodulation. Exons 5–7 in CHRNA7 can be duplicated and fused to exons A-E of FAR7a, resulting in a hybrid gene known as CHRFAM7A, unique to humans. Its product, denoted herein as Dupα7, is a truncated subunit where the N-terminal 146 residues of the ligand binding domain of the α7 receptor have been replaced by 27 residues from FAM7. Dupα7 negatively affects the functioning of α7 receptors associated with neurological disorders, including Alzheimer’s diseases and schizophrenia. However, the stoichiometry for the α7 nicotinic receptor containing dupα7 monomers remains unknown. In this work, we developed computational models of all possible combinations of wild-type α7 and dupα7 pentamers and evaluated their stability via atomistic molecular dynamics and coarse-grain simulations. We assessed the effect of dupα7 subunits on the Ca2+ conductance using free energy calculations. We showed that receptors comprising of four or more dupα7 subunits are not stable enough to constitute a functional ion channel. We also showed that models with dupα7/α7 interfaces are more stable and are less detrimental for the ion conductance in comparison to dupα7/dupα7 interfaces. Based on these models, we used protein–protein docking to evaluate how such interfaces would interact with an antagonist, α-bungarotoxin, and amyloid Aβ42 . Our findings show that the optimal stoichiometry of dupα7/α7 functional pentamers should be no more than three dupα7 monomers, in favour of a dupα7/α7 interface in comparison to a homodimer dupα7/dupα7 interface. We also showed that receptors bearing dupα7 subunits are less sensitive to Aβ42 effects, which may shed light on the translational gap reported for strategies focused on nicotinic receptors in ‘Alzheimer’s disease research.


Publication metadata

Author(s): Liu D, de Souza JV, Ahmad A, Bronowska AK

Publication type: Article

Publication status: Published

Journal: International Journal of Molecular Sciences

Year: 2021

Volume: 22

Issue: 11

Online publication date: 22/05/2021

Acceptance date: 20/05/2021

Date deposited: 09/06/2021

ISSN (print): 1661-6596

ISSN (electronic): 1422-0067

Publisher: MDPI AG

URL: https://doi.org/10.3390/ijms22115466

DOI: 10.3390/ijms22115466


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