Indispensability of Horizontally Transferred Genes and Its Impact on Bacterial Genome Streamlining
Indispensability of Horizontally Transferred Genes and Its Impact on Bacterial Genome Streamlining
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DOI：
10.1093/molbev/msw009
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发表时间：
2016-05-01
影响因子：
10.7
通讯作者：
Papp, Balazs
中科院分区：
文献类型：
--
作者：
Karcagi, Ildiko;Draskovits, Gabor;Papp, Balazs
为什么某些细菌的基因组如此小而紧凑？适应性基因组流线型假说认为，由于复制DNA的代谢负担，选择作用于减少基因组大小。为了揭示基因组精简对细胞性状的影响，我们通过删除在自然界中反复水平转移的区域，将大肠杆菌基因组减少了20%。出乎意料的是，水平转移的基因不仅可以利用特定的营养物质并提高对压力的耐受性，而且还可以有效地利用资源来构建新的细胞，从而影响常规和压力环境中的适应性。基因组减少影响健身不仅基因丢失，但也诱导一般的压力反应。最后，我们没有找到证据表明较小的基因组的优势是由于复制DNA的代谢负担减少或与较小的细胞大小有关。我们的结论是，由于删除短基因组片段所获得的潜在能量益处与这些删除的有害副作用相比微不足道，因此选择降低DNA合成成本不太可能塑造小基因组的进化。
Why are certain bacterial genomes so small and compact? The adaptive genome streamlining hypothesis posits that selection acts to reduce genome size because of themetabolic burden of replicating DNA. To reveal the impact of genome streamlining on cellular traits, we reduced the Escherichia coli genome by up to 20% by deleting regions which have been repeatedly subjects of horizontal transfer in nature. Unexpectedly, horizontally transferred genes not only confer utilization of specific nutrients and elevate tolerance to stresses, but also allow efficient usage of resources to build new cells, and hence influence fitness in routine and stressful environments alike. Genome reduction affected fitness not only by gene loss, but also by induction of a general stress response. Finally, we failed to find evidence that the advantage of smaller genomes would be due to a reduced metabolic burden of replicating DNA or a link with smaller cell size. We conclude that as the potential energetic benefit gained by deletion of short genomic segments is vanishingly small compared with the deleterious side effects of these deletions, selection for reduced DNA synthesis costs is unlikely to shape the evolution of small genomes.