Data from: The evolution of bat nucleic acid sensing Toll-like receptors

We characterized the nucleic acid sensing Toll-like receptors (TLR) of a New World bat species, the common vampire bat (Desmodus rotundus), and through a comparative molecular evolutionary approach searched for general adaptation patterns among the nucleic acid sensing TLRs of eight different bats species belonging to three families (Pteropodidae, Vespertilionidae and Phyllostomidae). We found that the bat TLRs are evolving slowly and mostly under purifying selection and that the divergence pattern of such receptors is overall congruent with the species tree, consistent with the evolution of many other mammalian nuclear genes. However, the chiropteran TLRs exhibited unique mutations fixed in ligand binding sites, some of which involved non-conservative amino acid changes and/or targets of positive selection. Such changes could potentially modify protein function and ligand biding properties, as some changes were predicted to alter nucleic acid binding motifs in TLR 9. Moreover, evidence for episodic diversifying selection acting specifically upon the bat lineage and sub lineages was detected. Thus, the long-term adaptation of chiropterans to a wide variety of environments and ecological niches with different pathogen profiles is likely to have shaped the evolution of the bat TLRs in an order-specific manner. The observed evolutionary patterns provide evidence for potential functional differences between bat and other mammalian TLRs in terms of resistance to specific pathogens or recognition of nucleic acids in general.我们对一种新大陆蝙蝠——普通吸血蝠（Desmodus rotundus）的核酸感知Toll样受体（Toll-like receptors, TLR）进行了特征分析，并通过比较分子进化方法，对隶属于翼手目三科——狐蝠科（Pteropodidae）、蝙蝠科（Vespertilionidae）和叶口蝠科（Phyllostomidae）——的8种不同蝙蝠的核酸感知TLR的普遍适应性模式展开了探究。研究发现，蝙蝠TLR进化速率较为缓慢，且整体处于纯化选择压力之下；这类受体的分化模式总体上与物种树一致，这与诸多其他哺乳动物核基因的演化规律相符。不过，翼手类TLR存在固定于配体结合位点的独特突变，其中部分突变涉及非保守氨基酸替换以及/或者正选择靶点。此类改变有可能改变蛋白质功能与配体结合特性——部分突变被预测会改变TLR 9的核酸结合基序。此外，研究还检测到仅作用于蝙蝠类群及其亚支系的间歇式多样化选择证据。因此，翼手类长期适应多样环境与携带不同病原体谱的生态位的演化历程，很可能以类群特异性的方式塑造了蝙蝠TLR的进化。本次观测到的演化模式表明，蝙蝠与其他哺乳动物的TLR在抵抗特定病原体或常规核酸识别能力方面，存在潜在的功能差异。