State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen 361000, China.
Guangdong Provincial Key Laboratory of Fishery Ecology and Environment, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China.
Mar Drugs. 2018 Dec 7;16(12):491. doi: 10.3390/md16120491.
Paralytic shellfish toxins (PSTs) are a group of potent neurotoxic alkaloids that are produced mainly by marine dinoflagellates. PST biosynthesis in dinoflagellates is a discontinuous process that is coupled to the cell cycle. However, little is known about the molecular mechanism underlying this association. Here, we compared global protein expression profiles of a toxigenic dinoflagellate, , collected at four different stages of toxin biosynthesis during the cell cycle, using an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomic approach. The results showed that toxin biosynthesis occurred mainly in the G1 phase, especially the late G1 phase. In total, 7232 proteins were confidently identified, and 210 proteins exhibited differential expression among the four stages. Proteins involved in protein translation and photosynthetic pigment biosynthesis were significantly upregulated during toxin biosynthesis, indicating close associations among the three processes. Nine toxin-related proteins were detected, and two core toxin biosynthesis proteins, namely, sxtA and sxtI, were identified for the first time in dinoflagellates. Among these proteins, sxtI and ompR were significantly downregulated when toxin biosynthesis stopped, indicating that they played important roles in the regulation of PST biosynthesis. Our study provides new insights into toxin biosynthesis in marine dinoflagellates: nitrogen balance among different biological processes regulates toxin biosynthesis, and that glutamate might play a key modulatory role.
麻痹性贝类毒素（PSTs）是一组强效神经毒素生物碱，主要由海洋甲藻产生。甲藻中的 PST 生物合成是一个不连续的过程，与细胞周期偶联。然而，关于这种关联的分子机制知之甚少。在这里，我们使用基于等重同位素标记相对和绝对定量（iTRAQ）的定量蛋白质组学方法，比较了产毒甲藻 在细胞周期中 PST 生物合成的四个不同阶段采集的蛋白质表达谱。结果表明，毒素生物合成主要发生在 G1 期，特别是晚期 G1 期。总共鉴定出 7232 种蛋白质，其中 210 种蛋白质在四个阶段之间表现出差异表达。在毒素生物合成过程中，与蛋白质翻译和光合色素生物合成相关的蛋白质显著上调，表明这三个过程密切相关。检测到 9 种与毒素相关的蛋白质，首次在甲藻中鉴定出两种核心毒素生物合成蛋白 sxtA 和 sxtI。在这些蛋白质中，当毒素生物合成停止时，sxtI 和 ompR 显著下调，表明它们在 PST 生物合成的调控中发挥重要作用。我们的研究为海洋甲藻中的毒素生物合成提供了新的见解：不同生物过程之间的氮平衡调节毒素生物合成，谷氨酸可能发挥关键的调节作用。
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