A natural point mutation in the bitter taste receptor TAS2R16 causes inverse agonism of arbutin in lemur gustation

Bitter taste enables the detection of potentially harmful substances and is mediated by bitter taste receptors, TAS2Rs, in vertebrates. Few antagonists and inverse agonists of TAS2Rs have been identified, especially natural compounds. TAS2R16s in humans, apes and Old World monkeys (Catarrhini, Anthropoidea) recognise β-glucoside analogues as specific agonists. Here, we investigated responses of TAS2R16 to β-glucosides in non-anthropoid primates, namely, lemurs (Lemuriformes, Strepsirrhini). Salicin acted as an agonist on lemur TAS2R16. Arbutin acted as an agonist in the ring-tailed lemur (Lemur catta) but as an inverse agonist in black lemur (Eulemur macaco) and black-and-white ruffed lemur (Varecia variegata). We identified a strepsirrhine-specific amino acid substitution responsible for the inverse agonism of arbutin. In a food preference test, salicin bitterness was inhibited by arbutin in the black lemur. Structural modelling revealed this locus was important for a rearrangement of ...