Adaptive evolution in GroEL from distantly related endosymbiotic bacteria of insects
Adaptive evolution in GroEL from distantly related endosymbiotic bacteria of insects
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DOI：
10.1111/j.1420-9101.2004.00861.x
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发表时间：
2005-05-01
影响因子：
2.1
通讯作者：
Barrio, E
中科院分区：
文献类型：
--
作者：
Fares, MA;Moya, A;Barrio, E
细菌和昆虫之间的许多共生现象是由古老的感染引起的，然后是宿主谱系内严格的垂直传播。这种传播发生的强大瓶颈促进了遗传漂变对轻微有害突变的中性固定。正如穆勒棘轮所预测的那样，这种固定将通过不可逆转的适应性损失驱动内共生细菌。伴侣蛋白 GroEL 被认为是蚜虫内共生细菌持续存在的一种补偿机制。在这里，我们表明，来自两个系统发育上非常遥远的细菌门的昆虫的内共生细菌通过在参与 GroES/肽结合或参与 GroEL 顶端结构域的整体运动的功能重要的 GroEL 区域中的正选择来固定氨基酸取代。这些结果，加上这些内共生体中 GroEL 的高水平组成型表达，为了解负责维持共生生活方式的分子机制的进化提供了宝贵的见解。
Many symbioses between bacteria and insects resulted from ancient infections followed by strict vertical transmission within host lineages. The strong bottlenecks under which this transmission occurs promote the neutral fixation of slightly deleterious mutations by genetic drift. As predicted by Muller's ratchet, this fixation will drive endosymbiotic bacteria through an irreversible dynamics of fitness loss. The chaperonin GroEL has been proposed as a compensatory mechanism whereby endosymbiotic bacteria of aphids persist. Here, we show that endosymbiotic bacteria of insects from two phylogenetically very distant bacterial phyla have fixed amino acid substitutions by positive selection in functionally important GroEL regions involved in either GroES/peptide binding or in the en bloc movement of the GroEL apical domain. These results, together with the high levels of constitutive expression of GroEL in these endosymbionts, provide valuable insights into the evolution of a molecular mechanism responsible for the maintenance of the symbiotic lifestyle.