The bioenergetic costs of a gene
The bioenergetic costs of a gene
复制标题
DOI：
10.1073/pnas.1514974112
复制
发表时间：
2015-12-22
影响因子：
11.1
通讯作者：
Marinov, Georgi K.
中科院分区：
文献类型：
--
作者：
Lynch, Michael;Marinov, Georgi K.
进化基因组学的一个持久的谜团涉及真核生物，特别是多细胞物种中基因组大小的谱系特异性扩增的机制。有一种观点认为，所有过量的DNA都有突变危险，但足够弱，以至于基因组大小的扩张被动地出现在那些由于有效种群规模小而选择效率相对较低的物种中。另一种观点认为，如果没有真核生物谱系中定植线粒体提供的能量促进，大量的基因添加是不可能的。与后一种观点相反，对来自多种物种的细胞能量学和基因组学数据的分析表明，相对于细胞一生的ATP需求，在细菌和真核生物中，基因在DNA、RNA和蛋白质水平上的成本随着细胞体积的增加而下降。此外，在细菌种群中，这些代价通常足够大，可以通过自然选择感知，但在经历高水平随机遗传漂变的真核生物中则不然。因此，由于尚不清楚的缩放原因，仅凭借其大尺寸，真核细胞就有更广泛的机会来定植表现出弱优势甚至短暂不利表型效应的新基因。这些结果表明，线粒体的起源并不是基因组扩大的先决条件。
An enduring mystery of evolutionary genomics concerns the mechanisms responsible for lineage-specific expansions of genome size in eukaryotes, especially in multicellular species. One idea is that all excess DNA is mutationally hazardous, but weakly enough so that genome-size expansion passively emerges in species experiencing relatively low efficiency of selection owing to small effective population sizes. Another idea is that substantial gene additions were impossible without the energetic boost provided by the colonizing mitochondrion in the eukaryotic lineage. Contrary to this latter view, analysis of cellular energetics and genomics data from a wide variety of species indicates that, relative to the lifetime ATP requirements of a cell, the costs of a gene at the DNA, RNA, and protein levels decline with cell volume in both bacteria and eukaryotes. Moreover, these costs are usually sufficiently large to be perceived by natural selection in bacterial populations, but not in eukaryotes experiencing high levels of random genetic drift. Thus, for scaling reasons that are not yet understood, by virtue of their large size alone, eukaryotic cells are subject to a broader set of opportunities for the colonization of novel genes manifesting weakly advantageous or even transiently disadvantageous phenotypic effects. These results indicate that the origin of the mitochondrion was not a prerequisite for genome-size expansion.