Molecular Evolution and Functional Divergence of Trace Amine-Associated Receptors.
Molecular Evolution and Functional Divergence of Trace Amine-Associated Receptors.
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DOI：
10.1371/journal.pone.0151023
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Moriyama EN
中科院分区：
文献类型：
--
作者：
Eyun SI;Moriyama H;Hoffmann FG;Moriyama EN
痕量胺相关受体（TAAR）是G蛋白偶联受体超家族的成员，并且已知在嗅觉感觉神经元中表达。到目前为止，对TAAR的分子进化研究数量有限。为了阐明谱系特异性进化如何导致其功能分化，我们检查了30个后生动物基因组。总共从26个脊椎动物基因组中鉴定出493个TAAR候选基因（包括84个假基因）。未从非脊椎动物基因组中鉴定出TAAR。一个祖先型TAAR样基因似乎已经出现在七鳃鳗。我们发现了四个兽特有的TAAR亚科（一个真兽特有的和三个后生兽特有的），除了以前已知的九个亚科。许多种特异性TAAR基因的重复和丢失导致了哺乳动物之间TAAR基因数量的巨大变化，从海豚的0到狐蝠的26。基于对伯胺或叔胺的结合偏好以及它们的序列相似性，将TAAR分为两组。初级胺检测TAAR（TAAR 1 -4）出现较早，通常具有单拷贝直系同源物（很少重复或丢失），并在强大的功能限制下进化。相比之下，叔胺检测TAAR（TAAR 5 -9）最近出现，其中大多数经历了较高的基因复制率。属于叔胺检测TAAR组的蛋白质成员也显示出阳性选择的模式，特别是在配体结合口袋周围的区域，这可能会影响配体结合活性和特异性。叔胺检测TAAR基因家族的扩展可能在兽目哺乳动物的陆地适应中发挥了重要作用。TAAR基因家族的分子进化似乎受到环境和进化因素之间复杂的、物种特异性的相互作用的支配。
Trace amine-associated receptors (TAARs) are a member of the G-protein-coupled receptor superfamily and are known to be expressed in olfactory sensory neurons. A limited number of molecular evolutionary studies have been done for TAARs so far. To elucidate how lineage-specific evolution contributed to their functional divergence, we examined 30 metazoan genomes. In total, 493 TAAR gene candidates (including 84 pseudogenes) were identified from 26 vertebrate genomes. TAARs were not identified from non-vertebrate genomes. An ancestral-type TAAR-like gene appeared to have emerged in lamprey. We found four therian-specific TAAR subfamilies (one eutherian-specific and three metatherian-specific) in addition to previously known nine subfamilies. Many species-specific TAAR gene duplications and losses contributed to a large variation of TAAR gene numbers among mammals, ranging from 0 in dolphin to 26 in flying fox. TAARs are classified into two groups based on binding preferences for primary or tertiary amines as well as their sequence similarities. Primary amine-detecting TAARs (TAAR1-4) have emerged earlier, generally have single-copy orthologs (very few duplication or loss), and have evolved under strong functional constraints. In contrast, tertiary amine-detecting TAARs (TAAR5-9) have emerged more recently and the majority of them experienced higher rates of gene duplications. Protein members that belong to the tertiary amine-detecting TAAR group also showed the patterns of positive selection especially in the area surrounding the ligand-binding pocket, which could have affected ligand-binding activities and specificities. Expansions of the tertiary amine-detecting TAAR gene family may have played important roles in terrestrial adaptations of therian mammals. Molecular evolution of the TAAR gene family appears to be governed by a complex, species-specific, interplay between environmental and evolutionary factors.