Adaptive evolution of metabolic pathways in Drosophila
Adaptive evolution of metabolic pathways in Drosophila
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DOI：
10.1093/molbev/msm057
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发表时间：
2007-06-01
影响因子：
10.7
通讯作者：
Eanes, W. F.
中科院分区：
文献类型：
--
作者：
Flowers, J. M.;Sezgin, E.;Eanes, W. F.
酶变异的适应性意义一直是群体遗传学的核心兴趣。然而，在生物化学途径的更大背景下，自然选择如何对酶起作用还没有得到广泛的探索。一个基本的期望是，代谢表型的自然选择将针对控制代谢流量的酶，但适应性变异如何在代谢网络中的酶之间分布还知之甚少。在这里，我们使用群体遗传学的方法来确定酶的适应性选择在果蝇和果蝇simulans的中央代谢途径。我们报告了17个基因的多态性和分歧的数据，编码酶的5个代谢途径，汇聚在葡萄糖-6-磷酸（G6 P）。偏离中立的期望，观察到在五个位点。在编码糖酵解酶的10个基因中，只有醛缩酶（Ald）偏离中性。与中性进化不一致的其他4个基因（葡萄糖-6-磷酸脱氢酶[G6 pd]）、磷酸葡萄糖变位酶[Pgm]、海藻糖-6-磷酸合成酶[Tps 1]和葡萄糖-6-磷酸酶[G6 pase]编码G6 P分支点酶，这些酶在戊糖-磷酸、糖原生成、海藻糖合成和糖原生成途径的入口点催化反应。我们调和这些结果与人口遗传学理论和现有的参数代谢调节，并提出在这个系统中的适应性选择的发病率是有关的流量控制的分布。这些数据表明，G6 P分支点酶的适应性进化可能在代谢适应中具有特殊意义。
The adaptive significance of enzyme variation has been of central interest in population genetics. Yet, how natural selection operates on enzymes in the larger context of biochemical pathways has nor been broadly explored. A basic expectation is that natural selection on metabolic phenotypes will target enzymes that control metabolic flux, but how adaptive variation is distributed among enzymes in metabolic networks is poorly understood. Here, we use population genetic methods to identify enzymes responding to adaptive selection in the pathways of central metabolism in Drosophila melanogaster and Drosophila simulans. We report polymorphism and divergence data for 17 genes that encode enzymes of 5 metabolic pathways that converge at glucose-6-phosphate (G6P). Deviations from neutral expectations were observed at five loci. Of the 10 genes that encode the enzymes of glycolysis, only aldolase (Ald) deviated from neutrality. The other 4 genes that were inconsistent with neutral evolution (glucose-6-phosphate dehydrogenase [G6pd]), phosphoglucomutase [Pgm], trehalose-6-phosphate synthetase [Tps1], and glucose-6phosphatase [G6pase] encode G6P branch point enzymes that catalyze reactions at the entry point to the pentose-phosphate, glycogenic, trehalose synthesis, and gluconeogenic pathways. We reconcile these results with population genetics theory and existing arguments on metabolic regulation and propose that the incidence of adaptive selection in this system is related to the distribution of flux control. The data suggest that adaptive evolution of G6P branch point enzymes may have special significance in metabolic adaptation.