Signatures of selection in the human olfactory receptor OR5I1 gene.
The human olfactory receptor (OR) repertoire is reduced in comparison to other mammals and to other nonhuman primates. Nonetheless, this olfactory decline opens an opportunity for evolutionary innovation and improvement. In the present study, we focus on an OR gene, OR5I1, which had previously been shown to present an excess of amino acid replacement substitutions between humans and chimpanzees. We analyze the genetic variation in OR5I1 in a large worldwide human panel and find an excess of derived alleles segregating at relatively high frequencies in all populations. Additional evidence for selection includes departures from neutrality in allele frequency spectra tests but no unusually extended haplotype structure. Moreover, molecular structural inference suggests that one of the nonsynonymous polymorphisms defining the presumably adaptive protein form of OR5I1 may alter the functional binding properties of the OR. These results are compatible with positive selection having modeled the pattern of variation found in the OR5I1 gene and with a relatively ancient, mild selective sweep predating the "Out of Africa" expansion of modern humans.
Moreno-Estrada
Andrés
A
Unitat de Biologia Evolutiva, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain.
Casals
Ferran
F
Ramírez-Soriano
Anna
A
Oliva
Baldo
B
Calafell
Francesc
F
Bertranpetit
Jaume
J
Bosch
Elena
E
D019943:Amino Acid Substitution; D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D008957:Models, Genetic; D002679:Pan troglodytes; D011110:Polymorphism, Genetic; D043562:Receptors, G-Protein-Coupled / Q000235:genetics*; D018035:Receptors, Odorant / Q000235:genetics*; D013045:Species Specificity
C530088:OR5l1 protein, human; D043562:Receptors, G-Protein-Coupled; D018035:Receptors, Odorant