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Sci Rep

Title:		The directed evolution of ligand specificity in a GPCR and the unequal contributions of efficacy and affinity
Author(s):		Di Roberto RB; Chang B; Peisajovich SG;
Address:		"Department of Cell and Systems Biology, University of Toronto 25 Harbord Street, Toronto, ON, M5S 3G5, Canada. raphael.brissetdiroberto@mail.utoronto.ca. Department of Cell and Systems Biology, University of Toronto 25 Harbord Street, Toronto, ON, M5S 3G5, Canada"
Journal Title:		Sci Rep
Year:		2017
Volume:		20171122
Issue:		1
Page Number:		16012 -
DOI:		10.1038/s41598-017-16332-2
ISSN/ISBN:		2045-2322 (Electronic) 2045-2322 (Linking)
Abstract:		"G protein-coupled receptors (GPCRs) must discriminate between hundreds of related signal molecules. In order to better understand how GPCR specificity can arise from a common promiscuous ancestor, we used laboratory evolution to invert the specificity of the Saccharomyces cerevisiae mating receptor Ste2. This GPCR normally responds weakly to the pheromone of the related species Kluyveromyces lactis, though we previously showed that mutation N216S is sufficient to make this receptor promiscuous. Here, we found that three additional substitutions, A265T, Y266F and P290Q, can act together to confer a novel specificity for K. lactis pheromone. Unlike wild-type Ste2, this new variant does not rely on differences in binding affinity to discriminate against its non-preferred ligand. Instead, the mutation P290Q is critical for suppressing the efficacy of the native pheromone. These two alternative methods of ligand discrimination were mapped to specific amino acid positions on the peptide pheromones. Our work demonstrates that changes in ligand efficacy can drive changes in GPCR specificity, thus obviating the need for extensive binding pocket re-modeling"
Keywords:		"Kluyveromyces/genetics/metabolism Mutation Receptors, G-Protein-Coupled/genetics/*metabolism Saccharomyces cerevisiae/genetics/metabolism Saccharomyces cerevisiae Proteins/genetics/metabolism;"
Notes:		"MedlineDi Roberto, Raphael B Chang, Belinda Peisajovich, Sergio G eng Research Support, Non-U.S. Gov't England 2017/11/24 Sci Rep. 2017 Nov 22; 7(1):16012. doi: 10.1038/s41598-017-16332-2"