Molecular reconstruction of recurrent evolutionary switching in olfactory receptor specificity
Abstract
Olfactory receptor repertoires exhibit remarkable functional diversity, but how these proteins have evolved is poorly understood. Through analysis of extant and ancestrally-reconstructed drosophilid olfactory receptors from the Ionotropic receptor (Ir) family, we investigated evolution of two organic acid-sensing receptors, Ir75a and Ir75b. Despite their low amino acid identity, we identify a common 'hotspot' in their ligand-binding pocket that has a major effect on changing the specificity of both Irs, as well as at least two distinct functional transitions in Ir75a during evolution. Moreover, we show that odor specificity is refined by changes in additional, receptor-specific sites, including those outside the ligand-binding pocket. Our work reveals how a core, common determinant of ligand-tuning acts within epistatic and allosteric networks of substitutions to lead to functional evolution of olfactory receptors.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1, 2, 3 and 5.
Article and author information
Author details
Funding
European Molecular Biology Organisation (ALTF 940-2019)
- Hayden R Schmidt
Human Frontier Science Program Young Investigator Award (RGY0073/2011)
- Richard Benton
Helen Hay Whitney Foundation
- Hayden R Schmidt
FP7 Ideas: European Research Council (802531)
- Lucia L Prieto-Godino
Cancer Research UK (FC001594)
- Lucia L Prieto-Godino
Medical Research Council (FC001594)
- Lucia L Prieto-Godino
Wellcome Trust (FC001594)
- Lucia L Prieto-Godino
FP7 Ideas: European Research Council (615094)
- Richard Benton
FP7 Ideas: European Research Council (833548)
- Richard Benton
Swiss National Science Foundation Nano-Tera (20NA21_143082)
- Richard Benton
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Prieto-Godino et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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