Tuning Properties of Avian and Frog Bitter Taste Receptors Dynamically Fit Gene Repertoire sizes
Tuning Properties of Avian and Frog Bitter Taste Receptors Dynamically Fit Gene Repertoire sizes
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DOI：
10.1093/molbev/msu254
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发表时间：
2014-12-01
影响因子：
10.7
通讯作者：
Meyerhof, Wolfgang
中科院分区：
文献类型：
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作者：
Behrens, Maik;Korsching, Sigrun I.;Meyerhof, Wolfgang
脊椎动物的苦味感知依赖于苦味受体数量的可变基因，范围从鸡肉中的三个功能基因到青蛙的大约50个。人类具有中型TAS2R曲目，该曲目编码三个，几个狭窄的受体以及具有中间调谐特性的受体。这种调整信息不适合其他脊椎动物的苦味受体。特别是尚不清楚，是否可以通过对这些受体进行广泛调整来补偿小的TAS2R曲目，而在另一侧，大曲目是否可能导致狭窄的调谐受体。为了阐明这个问题，我们克隆了所有三个鸡TAS2R，两个土耳其TAS2R，三个斑马雀科Tas2rs和六个西方爪的claw爪子青蛙代表系统发育树的主要分支，并用46种不同的苦味化合物筛选它们。所有鸡肉和土耳其TAS2R均已广泛调整，斑马雀科Tas2r进行了狭窄的调节，青蛙TAS2R的范围从广泛到狭窄的受体不等。我们得出的结论是，较少的功能性TAS2R基因本身并不意味着苦味本身的重要性降低，因为它可以通过大型调整宽度来补偿。大量功能性TAS2R基因似乎允许使用特定物种特定相关性的毒素的专用受体的演变。总而言之，我们表明，调谐广度，重叠的激动剂曲线和交错的有效激动剂浓度范围是人和其他脊椎动物TAS2RS的共享特征。
Bitter taste perception in vertebrates relies on a variable number of bitter taste receptor (Tas2r) genes, ranging from only three functional genes in chicken to as many as approximately 50 in frogs. Humans possess a medium-sized Tas2r repertoire encoding three broadly and several narrowly tuned receptors plus receptors with intermediate tuning properties. Such tuning information is not available for bitter taste receptors of other vertebrate species. In particular it is not known, whether a small Tas2r repertoire may be compensated for by broad tuning of these receptors, and on the other side, whether a large repertoire might entail a preponderance of narrowly tuned receptors. To elucidate this question, we cloned all three chicken Tas2rs, the two turkey Tas2rs, three zebra finch Tas2rs, and six Tas2rs of the Western clawed frog representative of major branches of the phylogenetic tree, and screened them with 46 different bitter compounds. All chicken and turkey Tas2rs were broadly tuned, the zebra finch Tas2rs were narrowly tuned, and frog Tas2rs ranged from broadly to narrowly tuned receptors. We conclude that a low number of functional Tas2r genes does not imply a reduced importance of bitter taste per se, as it can be compensated by large tuning width. A high number of functional Tas2r genes appears to allow the evolution of specialized receptors, possibly for toxins with species-specific relevance. In sum, we show that variability in tuning breadth, overlapping agonist profiles, and staggered effective agonist concentration ranges are shared features of human and other vertebrate Tas2rs.