Episodic adaptive evolution of primate lysozymes
Episodic adaptive evolution of primate lysozymes
复制标题
DOI：
10.1038/385151a0
复制
发表时间：
1997-01-09
期刊：
影响因子：
64.8
通讯作者：
Stewart, CB
中科院分区：
文献类型：
--
作者：
Messler, W;Stewart, CB
尽管达尔文的适应概念在近一个世纪前就已经建立，但很难严格证明来自不同物种的同源蛋白质之间的氨基酸差异具有适应性意义。目前对来自不同物种的蛋白质进行正达尔文选择的序列测试主要有两种类型：序列收敛和中性率违规（参考文献1中综述）。来自牛和叶猴这两种在前肠中发酵的哺乳动物的胃中的溶菌酶是同源蛋白质之间氨基酸序列趋同的一个例子(2,3) (4,6)。在这里，我们将中性率破坏测试与祖先序列重建结合起来，记录了导致前肠发酵疣猴共同祖先的谱系的正选择事件。该分析还检测到了现代人科动物溶菌酶共同祖先谱系中先前未曾怀疑的适应性事件。两次适应性事件之后都发生了负选择事件。因此，这种方法可以检测适应性和纯化事件，并将它们定位到蛋白质进化过程中的特定谱系。
ALTHOUGH the darwinian concept of adaptation was established nearly a century ago, it has been difficult to demonstrate rigorously that the amino-acid differences between homologous proteins from different species have adaptive significance, There are currently two major types of sequence tests for positive darwinian selection on proteins from different species: sequence convergence, and neutral rate violation (reviewed in ref. 1). Lysozymes from the stomachs of cows and langur monkeys, two mammalian species displaying fermentation in the foregut, are an example(2,3) of amino-acid sequence convergence among homologous proteins(4,6). Here we combine tests of neutral rate violation with reconstruction of ancestral sequences to document an episode of positive selection on the lineage leading to the common ancestor of the foregut-fermenting colobine monkeys. This analysis also detected a previously unsuspected adaptive episode on the lineage leading to the common ancestor of the modern hominoid lysozymes. Both adaptive episodes were followed by episodes of negative selection. Thus this approach can detect adaptive and purifying episodes, and localize them to specific lineages during protein evolution.