Characterization of the Binding Site of Aspartame in the Human Sweet Taste Receptor
Characterization of the Binding Site of Aspartame in the Human Sweet Taste Receptor
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DOI：
10.1093/chemse/bjv045
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发表时间：
2015-10-01
期刊：
影响因子：
3.5
通讯作者：
Max, Marianna
中科院分区：
文献类型：
--
作者：
Maillet, Emeline L.;Cui, Meng;Max, Marianna
甜味受体是由T1R2和T1R3组成的异二聚体G蛋白偶联受体，其将糖、小分子甜味剂和甜蛋白结合到多个结合位点。二肽甜味剂，甜菜碱结合在T1R2的维纳斯捕蝇器模块（VFTM）中。我们开发了人T1R2和人T1R3 VFTM及其二聚体的开放和封闭形式的同源模型，然后将T1R2的VFTM的封闭形式对接到T1R3中。为了测试和完善我们的模型的预测，我们突变了各种T1R2 VFTM残基，测定了突变体的活性并鉴定了11个关键残基（S40，Y103，D142，S144，S165，S168，Y215，D278，E302，D307，和R383）在甜味受体的结合口袋中或接近甜味受体的结合口袋，这对于配体识别和甜素的活性是重要的。此外，我们提出，结合是依赖于2个水分子位于配体口袋中的桥梁2个羰基基团的甜菜碱残基D142和L279。这些结果揭示了激活机制以及甜味受体的T1R2单体的细胞外结构域产生的信号传递如何导致甜味的感知。
The sweet taste receptor, a heterodimeric G protein- coupled receptor comprised of T1R2 and T1R3, binds sugars, small molecule sweeteners, and sweet proteins to multiple binding sites. The dipeptide sweetener, aspartame binds in the Venus Flytrap Module (VFTM) of T1R2. We developed homology models of the open and closed forms of human T1R2 and human T1R3 VFTMs and their dimers and then docked aspartame into the closed form of T1R2's VFTM. To test and refine the predictions of our model, we mutated various T1R2 VFTM residues, assayed activity of the mutants and identified 11 critical residues (S40, Y103, D142, S144, S165, S168, Y215, D278, E302, D307, and R383) in and proximal to the binding pocket of the sweet taste receptor that are important for ligand recognition and activity of aspartame. Furthermore, we propose that binding is dependent on 2 water molecules situated in the ligand pocket that bridge 2 carbonyl groups of aspartame to residues D142 and L279. These results shed light on the activation mechanism and how signal transmission arising from the extracellular domain of the T1R2 monomer of the sweet receptor leads to the perception of sweet taste.