条斑紫菜丝状体与叶状体类囊体膜蛋白光系统I复合体的分离、鉴定及组成差异研究

Porphyra yezoensis is an important economic algae in China, which takes important position in the plant evolution. It processes special photosystem I light harvesting system and was considered the linker of phycobilisome in Cyanobacteria and typical light harvesting complex (LHCI) in higher plants and green algae. However, its composition is still unknown. Moreover, the living condition of conchocelis and blades are significantly different, which directly affect the production. Our latest results indicated that there are significant differences between conchocelis and blades in photosystems I (PSI) and light-harvesting complexes (LHCI) organization. Therefore, this project attempt to isolate and purify PSI and LHCI complexes of conchocelis and blades, and identify the number and type of Lhcr combined with PSI. The native state PSI-LHCI complex will be separated to compare the similarities and differences between the conchocelis and blades antennas. The composition and function of the different protein complexes will also be analyzed to determine the adaptation of the conchocelis and blades to their living conditions. The completion of this project can not only help to make clear the evolutionary mechanism of the PSI antenna systems in algae, but also provide theoretical guidance for the cultivation of intertidal economic seaweed, which has important theoretical and economic significance.

条斑紫菜是我国重要的经济海藻，也是植物进化过程中的重要代表藻类。其光系统I (PSI)捕光天线在进化上及其特殊，被认为是由藻胆体向类囊体跨膜捕光复合体（LHCI）的过渡者，但其组成至今尚不清楚。此外，条斑紫菜丝状体与叶状体生长环境差异显著，对光照条件适应机制明显不同，并直接影响了条斑紫菜的生产实践。我们最新的研究结果表明丝状体PSI-LHCI的组织形式与叶状体相比差异明显。本项目将分别以丝状体和叶状体为研究对象，分离PSI及LHCI复合体，鉴定PSI结合Lhcr的数量及类型，并比较与高等植物及单细胞红藻LHCI的异同；分离丝状体与叶状体native形式的PSI-LHCI复合体，并分析组织形式的差异。依据差异蛋白复合体的组成及功能，阐明丝状体与叶状体对不同光照条件的适应机制。项目的完成不仅有助于从进化角度理解藻类PSI天线系统的演化过程，更能为潮间带经济海藻的栽培实践提供理论指导。

条斑紫菜是我国重要的经济海藻，具有重要的经济价值。作为潮间带大型红藻的代表，条斑紫菜占据重要的进化位置。条斑紫菜光系统组成特殊，不同世代的藻体形态及生理特性差异很大。本项目主要分离了条斑紫菜不同生活史阶段的光系统I蛋白复合体，研究了其组成及功能差异，结果表明丝状体和叶状体含有不同类型的与膜结合的捕光蛋白，且丝状体中PSI/PSII的比率较高；发现了一个丝状体特有的大分子量蛋白复合体，对该复合体进行了分离纯化、组成鉴定以及功能分析，发现该复合体对丝状体的环境适应性至关重要；比较分析了丝状体和叶状体对不同生活环境条件的适应机制。此外，通过基因遗传转化手段对关键蛋白PyLHCI进行了功能研究，首次发现了大型海藻基因遗传转化过程中的“共抑制”现象并解析了其发生机制。结果表明PyLHCI与紫菜生活史转化调控相关，“共抑制”叶状体藻株能释放大量的果孢子，进而发育成为丝状体。项目的完成对条斑紫菜丝状体培育及叶状体栽培均具有重要的指导意义，同时也为条斑紫菜的基因工程育种提供了重要思路。