Systemic Cold Stress Adaptation of Chlamydomonas reinhardtii*
Systemic Cold Stress Adaptation of Chlamydomonas reinhardtii*
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DOI：
10.1074/mcp.m112.026765
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发表时间：
2013-04
影响因子：
7
通讯作者：
L. Valledor;T. Furuhashi;A. Hanak;W. Weckwerth
中科院分区：
文献类型：
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作者：
L. Valledor;T. Furuhashi;A. Hanak;W. Weckwerth
莱茵衣藻是当今最重要的模式生物之一，其系统发育介于高等植物和动物之间(Merchant等人)。2007)。这种单细胞模型藻类的压力适应能力是人们关注的焦点，因为它与生物质和生物燃料生产有关。在这里，我们研究了莱茵哈蒂藻的冷胁迫适应，到目前为止还没有对这种藻类进行描述，但在高等植物中进行了深入的研究。为了达到这一目标，本研究利用高通量质谱仪对蛋白质组、代谢组、生理和细胞形态在0~120h内的变化进行了研究，并利用RT-qPCR技术对参与中枢代谢、信号转导和脂质生物合成的靶基因进行了分析。利用这种方法，中心代谢的动态被连接到冷胁迫依赖的糖和自噬途径，以及莱茵哈迪尔乳杆菌中的新基因，如CKIN1，CKIN2和一个迄今为止功能未被注释的蛋白CKIN3。冷胁迫对细胞的生理和组织产生了广泛的影响。糖异生和淀粉生物合成途径被激活，导致显著的淀粉和糖积累。定量脂谱显示，亲脂部分急剧减少，多不饱和脂肪酸增加，这表明这是维持膜流动性的一种机制。蛋白质组在冷胁迫期间被完全重塑：核糖体和剪接体的特定候选表明对低温适应至关重要的蛋白质的生物合成和降解发生了变化。特定蛋白酶体的降解可能是由观察到的泛素化系统中的冷特异性变化所介导的。以蛋白质为预测因子，以Fv/Fm、Fw、总脂和淀粉为反应因子，采用稀疏偏最小二乘回归分析进行蛋白质相关网络分析。我们还应用了格兰杰因果关系分析，揭示了蛋白质和代谢物之间的相关性，否则就无法检测到。对寒冷反应的蛋白质中，有20%是未经鉴定的蛋白质。这为藻类和植物的冷胁迫生物学的新发现提供了相当大的资源。
Chlamydomonas reinhardtii is one of the most important model organisms nowadays phylogenetically situated between higher plants and animals (Merchant et al. 2007). Stress adaptation of this unicellular model algae is in the focus because of its relevance to biomass and biofuel production. Here, we have studied cold stress adaptation of C. reinhardtii hitherto not described for this algae whereas intensively studied in higher plants. Toward this goal, high throughput mass spectrometry was employed to integrate proteome, metabolome, physiological and cell-morphological changes during a time-course from 0 to 120 h. These data were complemented with RT-qPCR for target genes involved in central metabolism, signaling, and lipid biosynthesis. Using this approach dynamics in central metabolism were linked to cold-stress dependent sugar and autophagy pathways as well as novel genes in C. reinhardtii such as CKIN1, CKIN2 and a hitherto functionally not annotated protein named CKIN3. Cold stress affected extensively the physiology and the organization of the cell. Gluconeogenesis and starch biosynthesis pathways are activated leading to a pronounced starch and sugar accumulation. Quantitative lipid profiles indicate a sharp decrease in the lipophilic fraction and an increase in polyunsaturated fatty acids suggesting this as a mechanism of maintaining membrane fluidity. The proteome is completely remodeled during cold stress: specific candidates of the ribosome and the spliceosome indicate altered biosynthesis and degradation of proteins important for adaptation to low temperatures. Specific proteasome degradation may be mediated by the observed cold-specific changes in the ubiquitinylation system. Sparse partial least squares regression analysis was applied for protein correlation network analysis using proteins as predictors and Fv/Fm, FW, total lipids, and starch as responses. We applied also Granger causality analysis and revealed correlations between proteins and metabolites otherwise not detectable. Twenty percent of the proteins responsive to cold are uncharacterized proteins. This presents a considerable resource for new discoveries in cold stress biology in alga and plants.