Differential enzyme targeting as an evolutionary adaptation to herbivory in Carnivora
Differential enzyme targeting as an evolutionary adaptation to herbivory in Carnivora
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DOI：
10.1093/molbev/msh054
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发表时间：
2004-04-01
影响因子：
10.7
通讯作者：
Danpure, CJ
中科院分区：
文献类型：
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作者：
Birdsey, GM;Lewin, J;Danpure, CJ
并不是所有的肉食目成员都是肉食性的。有些是杂食性的，少数，如大熊猫大熊猫，几乎完全是草食性的。尽管在食肉动物中认识到了一些对植物摄食量增加的适应，但在分子水平上研究的很少。一种广泛分布在哺乳动物中的对饮食的分子适应是对中间代谢酶丙氨酸的细胞内靶标：乙二酸氨基转移酶(AGT)，在食肉动物中倾向于线粒体，在草食动物中倾向于过氧化体，在杂食动物中倾向于线粒体和过氧化体。在本研究中，我们分析了AGT在食肉动物中的靶向性与物种的天然饮食的关系。我们不仅表明，随着饲料从主要肉食转向更杂食性和草食性的饮食，AGT靶向从线粒体到过氧化体的适应性转变，而且在一个谱系，即大熊猫的AGT中，有证据表明AGT线粒体靶向序列上的正选择压力降低了其效率，从而使更多的AGT被靶向Peroxisome。
Not all members of the order Carnivora are carnivorous. Some are omnivorous, and a few, such as the giant panda, Ailuropoda melanoleuca, are almost exclusively herbivorous. Although a number of adaptations to increased plant-eating are recognized within Carnivora, few have been studied at the molecular level. One molecular adaptation to diet that is spread widely across Mammalia is the differential intracellular targeting of the intermediary metabolic enzyme alanine:glyoxylate aminotransferase (AGT), which tends to be mitochondrial in carnivores, peroxisomal in herbivores, and both mitochondrial and peroxisomal in omnivores. In the present study, we have analyzed the targeting of AGT in Carnivora in relation to species' natural diets. We show not only that there has been an adaptive shift in AGT targeting from the mitochondrion toward the peroxisome as diets have shifted from being mainly carnivorous to ones that are more omnivorous and herbivorous but also that in one lineage, namely that of the giant panda, there is evidence for positive selection pressure at the molecular level on the AGT mitochondrial targeting sequence to decrease its efficiency, thereby allowing more AGT to be targeted to the peroxisomes.