The endosymbiotic relationship between cnidarians and photosynthetic dinoflagellate algae provides the foundation of coral reef ecosystems. This essential interaction is globally threatened by anthropogenic disturbance. As such, it is important to understand the molecular mechanisms underpinning the cnidarian-algal association. Here we investigated phosphorylation-mediated protein signalling as a mechanism of regulation of the cnidarian-algal interaction, and we report on the generation of the first phosphoproteome for the coral model system Aiptasia. Mass spectrometry-based phosphoproteomics using data-independent acquisition allowed consistent quantification of over 3,000 phosphopeptides totalling more than 1,600 phosphoproteins across aposymbiotic (symbiont-free) and symbiotic anemones. Comparison of the symbiotic states showed distinct phosphoproteomic profiles attributable to the differential phosphorylation of 539 proteins that cover a broad range of functions, from receptors to structural and signal transduction proteins. A subsequent pathway enrichment analysis identified the processes of "protein digestion and absorption," "carbohydrate metabolism," and "protein folding, sorting and degradation," and highlighted differential phosphorylation of the "phospholipase D signalling pathway" and "protein processing in the endoplasmic reticulum." Targeted phosphorylation of the phospholipase D signalling pathway suggests control of glutamate vesicle trafficking across symbiotic compartments, and phosphorylation of the endoplasmic reticulum machinery suggests recycling of symbiosome-associated proteins. Our study shows for the first time that changes in the phosphorylation status of proteins between aposymbiotic and symbiotic Aiptasia anemones may play a role in the regulation of the cnidarian-algal symbiosis. This is the first phosphoproteomic study of a cnidarian-algal symbiotic association as well as the first application of quantification by data-independent acquisition in the coral field.

中文翻译：

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有证据表明蛋白质磷酸化可维持刺鼻藻共生。

刺胞动物与光合藻鞭毛藻之间的内共生关系为珊瑚礁生态系统奠定了基础。这种必不可少的相互作用在全球范围内受到人为干扰的威胁。因此，重要的是要了解CNCN和藻类结合的分子机制。在这里，我们研究了磷酸化介导的蛋白质信号传导，作为调控刺胞-藻类相互作用的机制，并且我们报道了珊瑚模型系统Aiptasia的第一个磷酸化蛋白质组的生成。基于质谱的磷酸化蛋白质组学使用独立于数据的采集，可以对定量的无共生（无共生体）和共生的海葵中的3,000多种磷酸肽进行定量，总共超过1,600种磷蛋白。共生状态的比较显示了不同的磷酸化蛋白质组图谱，这归因于539种蛋白质的差异磷酸化，涵盖了从受体到结构和信号转导蛋白质的广泛功能。随后的途径富集分析确定了“蛋白质消化和吸收”，“碳水化合物代谢”和“蛋白质折叠，分类和降解”的过程，并突出了“磷脂酶D信号传导途径”和“内质中蛋白质加工”的差异磷酸化网状。” 磷脂酶D信号通路的靶向磷酸化表明，跨共生区室的谷氨酸囊泡运输受到控制，内质网机制的磷酸化表明共生体相关蛋白的回收。我们的研究首次表明，在单生共生和共生的Aiptasia海葵之间蛋白质的磷酸化状态的变化可能在调节刺id藻共生中起一定作用。这是对CNIDIAN-ALGAL共生关联的第一个磷酸化蛋白质组学研究，也是在珊瑚领域中通过不依赖数据的采集进行定量分析的第一个应用。