Lipidomic and transcriptomic analyses of Chlamydomonas reinhardtii under heat stress unveil a direct route for the conversion of membrane lipids into storage lipids
Lipidomic and transcriptomic analyses of Chlamydomonas reinhardtii under heat stress unveil a direct route for the conversion of membrane lipids into storage lipids
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DOI：
10.1111/pce.12656
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发表时间：
2016-04-01
影响因子：
7.3
通讯作者：
Li-Beisson, Y.
中科院分区：
文献类型：
--
作者：
Legeret, B.;Schulz-Raffelt, M.;Li-Beisson, Y.
研究光合细胞如何改变膜脂以应对热应激对于了解植物和微藻如何适应日常温度波动以及研究新的脂质途径非常重要。在这里，我们研究了模型光合微生物莱茵衣藻对热应激的早期响应过程中脂质分子种类和脂质代谢基因发生的变化。脂质分子种类分析表明，在 42 摄氏度下 60 分钟后，观察到特定多不饱和膜脂质的强烈减少，同时多不饱和三酰甘油 (TAG) 和二酰甘油 (DAG) 的增加。 DAG sn1-18:3/sn2-16:4 和 TAG sn1-18:3/sn2-16:4/sn3-18:3 的积累反映了主要叶绿体单半乳糖二酰基甘油 sn1-18:3/sn2-16:4 的减少，这表明新积累的 TAG 是通过单半乳糖基二酰基甘油直接转化为DAG 然后是 TAG。脂质组学分析表明，TAG 的第三种脂肪酸可能源自磷脂酰乙醇胺或二酰基甘油基-O-4-(N,N,N,-三甲基)-高丝氨酸甜菜碱脂质种类。通过比较转录组分析提供了该 TAG 合成途径的候选基因，其中包括磷脂酶 A2 同源物和 DAG 酰基转移酶 DGTT1。这项研究深入了解热应激期间膜脂变化的分子事件，并揭示了 TAG 合成的替代途径。 在模型光合生物莱茵衣藻中，我们表明质体膜对热应激的早期反应涉及通过转化为二酰基甘油和三酰基甘油来选择性减少多不饱和单半乳糖基甘油种类。通过热应激与对照细胞的比较转录组学来鉴定负责这种转化的候选基因。
Studying how photosynthetic cells modify membrane lipids in response to heat stress is important to understand how plants and microalgae adapt to daily fluctuations in temperature and to investigate new lipid pathways. Here, we investigate changes occurring in lipid molecular species and lipid metabolism genes during early response to heat stress in the model photosynthetic microorganism Chlamydomonas reinhardtii. Lipid molecular species analyses revealed that, after 60min at 42 degrees C, a strong decrease in specific polyunsaturated membrane lipids was observed together with an increase in polyunsaturated triacylglycerols (TAGs) and diacylglycerols (DAGs). The fact that decrease in the major chloroplastic monogalactosyldiacylglycerol sn1-18:3/sn2-16:4 was mirrored by an accumulation of DAG sn1-18:3/sn2-16:4 and TAG sn1-18:3/sn2-16:4/sn3-18:3 indicated that newly accumulated TAGs were formed via direct conversion of monogalactosyldiacylglycerols to DAGs then TAGs. Lipidomic analyses showed that the third fatty acid of a TAG likely originated from a phosphatidylethanolamine or a diacylglyceryl-O-4-(N,N,N,-trimethyl)-homoserine betaine lipid species. Candidate genes for this TAG synthesis pathway were provided through comparative transcriptomic analysis and included a phospholipase A2 homolog and the DAG acyltransferase DGTT1. This study gives insights into the molecular events underlying changes in membrane lipids during heat stress and reveals an alternative route for TAG synthesis.In the model photosynthetic organism Chlamydomonas reinhardtii, we show that the early response of plastidial membranes to heat stress involves selective reduction of polyunsaturated monogalactosylglycerol species by conversion to diacylglycerols and triacylglycerols. Candidate genes responsible for this conversion are identified by comparative transcriptomics of heat-stressed to control cells.