Department of Biotechnology/Molecular Plant Biology, University of Turku, Turku, Finland.
Department of Biology, Heinrich-Heine-Universität, Düsseldorf, Germany.
J Exp Bot. 2021 Jul 28;72(15):5553-5568. doi: 10.1093/jxb/erab216.
The kleptoplastic sea slug Elysia chlorotica consumes Vaucheria litorea, stealing its plastids, which then photosynthesize inside the animal cells for months. We investigated the properties of V. litorea plastids to understand how they withstand the rigors of photosynthesis in isolation. Transcription of specific genes in laboratory-isolated V. litorea plastids was monitored for 7 days. The involvement of plastid-encoded FtsH, a key plastid maintenance protease, in recovery from photoinhibition in V. litorea was estimated in cycloheximide-treated cells. In vitro comparison of V. litorea and spinach thylakoids was applied to investigate reactive oxygen species formation in V. litorea. In comparison to other tested genes, the transcripts of ftsH and translation elongation factor EF-Tu (tufA) decreased slowly in isolated V. litorea plastids. Higher levels of FtsH were also evident in cycloheximide-treated cells during recovery from photoinhibition. Charge recombination in PSII of V. litorea was found to be fine-tuned to produce only small quantities of singlet oxygen, and the plastids also contained reactive oxygen species-protective compounds. Our results support the view that the genetic characteristics of the plastids are crucial in creating a photosynthetic sea slug. The plastid's autonomous repair machinery is likely enhanced by low singlet oxygen production and elevated expression of FtsH.
食藻性海蛞蝓 Elysia chlorotica 摄取 Vaucheria litorea，窃取其质体，这些质体随后在动物细胞内进行数月的光合作用。我们研究了 Vaucheria litorea 质体的特性，以了解它们如何在孤立状态下耐受光合作用的严酷条件。在实验室分离的 Vaucheria litorea 质体中，特定基因的转录被监测了 7 天。用环己酰亚胺处理细胞，估算了参与 Vaucheria litorea 光抑制恢复的质体编码 FtsH（一种关键的质体维持蛋白酶）。还应用了 Vaucheria litorea 和菠菜类囊体体外比较，以研究 Vaucheria litorea 中活性氧物质的形成。与其他测试的基因相比，在分离的 Vaucheria litorea 质体中，ftsH 和翻译延伸因子 EF-Tu（tufA）的转录缓慢下降。在光抑制恢复期间，用环己酰亚胺处理的细胞中也存在更高水平的 FtsH。发现 Vaucheria litorea 中 PSII 的电荷复合被精细地调节，以产生少量的单线态氧，并且质体还含有活性氧物质保护化合物。我们的结果支持这样一种观点，即质体的遗传特征对于创造光合作用的海蛞蝓至关重要。质体的自主修复机制可能通过低单线态氧产生和 FtsH 的高表达得到增强。
