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Structure. 2017 Aug 1;25(8):1295-1302.e3. doi: 10.1016/j.str.2017.06.005. Epub 2017 Jul 6.

Ancestral Reconstruction Approach to Acetylcholine Receptor Structure and Function.

Author information

1
Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada.
2
Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, 10 Marie-Curie, Ottawa, ON K1N 6N5, Canada. Electronic address: cdacosta@uottawa.ca.

Abstract

Acetylcholine receptors (AChRs) are members of a superfamily of proteins called pentameric ligand-gated ion channels, which are found in almost all forms of life and thus have a rich evolutionary history. Muscle-type AChRs are heteropentameric complexes assembled from four related subunits (α, β, δ, and ɛ). Here we reconstruct the amino acid sequence of a β subunit ancestor shared by humans and cartilaginous fishes (i.e., Torpedo). Then, by resurrecting this ancestral β subunit and co-expressing it with human α, δ, and ɛ subunits, we show that despite 132 substitutions, the ancestral subunit is capable of forming human/ancestral hybrid AChRs. Whole-cell currents demonstrate that the agonist acetylcholine has reduced potency for hybrid receptors, while single-channel recordings reveal that hybrid receptors display reduced conductance and open probability. Our results outline a promising strategy for studies of AChR evolution aimed at identifying the amino acid origins of AChR structure and function.

KEYWORDS:

acetylcholine receptor; ancestral protein reconstruction; evolutionary biochemistry; ligand-gated ion channels; patch-clamp electrophysiology

PMID:
28689969
DOI:
10.1016/j.str.2017.06.005
[Indexed for MEDLINE]
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