Mammals use several chemosensory systems to detect and encode their chemical environment. How these systems discriminate relevant chemical cues is a major unresolved question. We hypothesize that differences in the stimulus selectivity of different populations of chemosensory cells largely reflects differences in the ligand selectivity and sensitivity of the chemosensory receptors (CRs) expressed therein. Difficulties in obtaining large amounts of receptor protein suitable for biochemical or structural analysis, as well as the small number of CRs for which ligands are known, has hampered efforts to characterize the basis of ligand specificity. One group of CRs, the T1R taste receptors, offers unique advantages that will permit the first systematic analysis of how CR structure/function relationships impact the ability of a chemosensory cell population to detect and discriminate physiologically relevant ligands. We will take advantage of the demonstrated sensitivity of T 1Rs for sweet-tasting ligands, and an extracellular N-terminal ligand-binding domain amenable to biochemical purification and structural characterization, to establish the role of different T1Rs in the detection of sweet tasting stimuli.
Aim 1 : The structure of the T1R ligand-binding pockets, in the presence and absence of ligands, will be solved by a combination of circular dichroism spectrophotometry and X-ray crystallography of T1R N-terminal domains.
Aim 2 : To determine the specific contributions of ligand binding to taste function, targeted mutations will be introduced in the ligand-binding pocket of T1R N-terminal domains both in vitro and by gene targeting in mice. Changes in ligand binding kinetics will be measured using isothermal titration calorimetry, while the effects of T1R deletion or mutation on taste function will be assayed by brief-access behavioral tasks where the sensitivity of targeted mice to sweet stimuli will be determined. Together, these studies will provide the first in-depth structural and quantitative analyses of the interactions between chemosensory receptors and their ligands, and will offer important new insights into how individual taste receptors contribute to the detection and discrimination of food cues critical for health and survival.
| Templeton, Catherine M; Ostovar pour, Saeideh; Hobbs, Jeanette R et al. (2011) Reduced sweetness of a monellin (MNEI) mutant results from increased protein flexibility and disruption of a distant poly-(L-proline) II helix. Chem Senses 36:425-34 |
| Dotson, Cedrick D; Vigues, Stephan; Steinle, Nanette I et al. (2010) T1R and T2R receptors: the modulation of incretin hormones and potential targets for the treatment of type 2 diabetes mellitus. Curr Opin Investig Drugs 11:447-54 |
| Dotson, Cedrick D; Shaw, Hillary L; Mitchell, Braxton D et al. (2010) Variation in the gene TAS2R38 is associated with the eating behavior disinhibition in Old Order Amish women. Appetite 54:93-9 |
| Spehr, Marc; Munger, Steven D (2009) Olfactory receptors: G protein-coupled receptors and beyond. J Neurochem 109:1570-83 |
| Martin, Bronwen; Dotson, Cedrick D; Shin, Yu-Kyong et al. (2009) Modulation of taste sensitivity by GLP-1 signaling in taste buds. Ann N Y Acad Sci 1170:98-101 |
| Vigues, S; Dotson, C D; Munger, S D (2009) The receptor basis of sweet taste in mammals. Results Probl Cell Differ 47:187-202 |
| Dotson, Cedrick D; Zhang, Lan; Xu, Hong et al. (2008) Bitter taste receptors influence glucose homeostasis. PLoS One 3:e3974 |
| Shin, Yu-Kyong; Martin, Bronwen; Golden, Erin et al. (2008) Modulation of taste sensitivity by GLP-1 signaling. J Neurochem 106:455-63 |
| Hobbs, J R; Munger, S D; Conn, G L (2007) Monellin (MNEI) at 1.15 A resolution. Acta Crystallogr Sect F Struct Biol Cryst Commun 63:162-7 |
| Nie, Yiling; Hobbs, Jeanette R; Vigues, Stephan et al. (2006) Expression and purification of functional ligand-binding domains of T1R3 taste receptors. Chem Senses 31:505-13 |
Showing the most recent 10 out of 13 publications
