Metabolic constraints for a novel symbiosis.
Metabolic constraints for a novel symbiosis.
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DOI：
10.1098/rsos.150708
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发表时间：
2016-03
影响因子：
3.5
通讯作者：
Wood AJ
中科院分区：
文献类型：
--
作者：
Sørensen ME;Cameron DD;Brockhurst MA;Wood AJ
古代进化事件很难研究，因为它们当前的产物是经过数百万年的适应而改变的衍生形式。初级内共生事件形成了第一个光合真核生物，产生了植物和藻类，对地球上的生命产生了巨大的影响。自该事件以来经过的进化时间意味着主导机制和所需的变化被掩盖了。最近在实验室建立的合成共生体，例如草履虫和蓝藻集胞藻 PC6803 之间的新型相互作用，为了解这一关键进化事件可能的早期轨迹提供了一个独特的窗口。在这里，我们应用代谢模型，使用通量平衡分析（FBA）来预测这种以前自由生活的共生体过渡到内共生生态位所需的代谢适应。通过实施互惠营养物交易，我们能够预测宿主和共生体最有效的营养物交换。在从自由生活到专性共生的转变过程中，交易参数很可能会随着时间的推移而改变，这导致我们的模型中首选交换营养物质的不连续变化。我们的研究结果表明，FBA 模型适用于由代谢交换驱动的古代进化转变，并预测受冲突支配的新建立的内共生体与已达到互利状态的成熟内共生体有何不同。
Ancient evolutionary events are difficult to study because their current products are derived forms altered by millions of years of adaptation. The primary endosymbiotic event formed the first photosynthetic eukaryote resulting in both plants and algae, with vast consequences for life on Earth. The evolutionary time that passed since this event means the dominant mechanisms and changes that were required are obscured. Synthetic symbioses such as the novel interaction between Paramecium bursaria and the cyanobacterium Synechocystis PC6803, recently established in the laboratory, permit a unique window on the possible early trajectories of this critical evolutionary event. Here, we apply metabolic modelling, using flux balance analysis (FBA), to predict the metabolic adaptations necessary for this previously free-living symbiont to transition to the endosymbiotic niche. By enforcing reciprocal nutrient trading, we are able to predict the most efficient exchange nutrients for both host and symbiont. During the transition from free-living to obligate symbiosis, it is likely that the trading parameters will change over time, which leads in our model to discontinuous changes in the preferred exchange nutrients. Our results show the applicability of FBA modelling to ancient evolutionary transitions driven by metabolic exchanges, and predict how newly established endosymbioses, governed by conflict, will differ from a well-developed one that has reached a mutual-benefit state.