Chimeric origins of ochrophytes and haptophytes revealed through an ancient plastid proteome
Chimeric origins of ochrophytes and haptophytes revealed through an ancient plastid proteome
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DOI：
10.7554/elife.23717
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发表时间：
2017-05-12
期刊：
影响因子：
7.7
通讯作者：
Bowler, Chris
中科院分区：
文献类型：
--
作者：
Dorrell, Richard G.;Gile, Gillian;Bowler, Chris
质体由核内编码并从细胞质输入的广泛蛋白质支持。这些质体靶向蛋白质可能完全来自内共生体、宿主或其他来源。在这里，我们确定并分析了770个质体靶向蛋白质，这些蛋白质在整个藻类中是保守的，藻类的一个主要群体包括硅藻、浮游植物和海带，它们具有来自红藻的质体。我们发现，祖先的赭色植物质体蛋白质组是一个进化的嵌合体，其遗传上易处理的核编码蛋白质的25%来自绿色藻类。我们还表明，宿主和质体蛋白质组的功能混合，如通过双靶向，是质体进化的祖先特征。最后，我们在另一个主要藻类谱系（附着植物）的质体靶向蛋白中检测到来自一个赭色植物亚群（包含大洋植物和网枝植物的谱系）的明确系统发育信号。这可能代表了一个可能的系列内共生事件深在真核生物进化史。
Plastids are supported by a wide range of proteins encoded within the nucleus and imported from the cytoplasm. These plastid-targeted proteins may originate from the endosymbiont, the host, or other sources entirely. Here, we identify and characterise 770 plastid targeted proteins that are conserved across the ochrophytes, a major group of algae including diatoms, pelagophytes and kelps, that possess plastids derived from red algae. We show that the ancestral ochrophyte plastid proteome was an evolutionary chimera, with 25% of its phylogenetically tractable nucleus-encoded proteins deriving from green algae. We additionally show that functional mixing of host and plastid proteomes, such as through dual-targeting, is an ancestral feature of plastid evolution. Finally, we detect a clear phylogenetic signal from one ochrophyte subgroup, the lineage containing pelagophytes and dictyochophytes, in plastid targeted proteins from another major algal lineage, the haptophytes. This may represent a possible serial endosymbiosis event deep in eukaryotic evolutionary history.