Characterization of photosystem I antenna proteins in the prasinophyte Ostreococcus tauri.
Characterization of photosystem I antenna proteins in the prasinophyte Ostreococcus tauri.
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DOI：
10.1016/j.bbabio.2010.04.017
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
W. Swingley;Masakazu Iwai;Yang Chen;Shin-ichiro Ozawa;K. Takizawa;Yuichiro Takahashi;J. Minagawa
中科院分区：
文献类型：
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作者：
W. Swingley;Masakazu Iwai;Yang Chen;Shin-ichiro Ozawa;K. Takizawa;Yuichiro Takahashi;J. Minagawa
Prasinophyceae是一类早期分支的真核绿色藻类。这些微型浮游植物在整个海洋中无处不在，对全球碳固定做出了巨大贡献。作为第一个被测序的光合植物，金牛牡蛎是研究光合真核生物捕光系统功能进化的模式生物。在这项研究中，我们分离和表征O。Tauri色素蛋白复合物。两个光系统I（PSI）的馏分，除了获得自由捕光复合物（LHC）馏分和光系统II（PSII）核心馏分通过蔗糖密度梯度离心。较小的PSI级分包含PSI核心蛋白LHCI，其在所有绿色植物中是保守的，Lhcp 1，一种prasinophyte特异性LHC蛋白，以及次要的单体LHC II蛋白CP 26和CP 29。较大的PSI级分包含相同的天线蛋白作为较小的，与Lhca 6和Lhcp 2的添加，和30%的较大的吸收截面。当O. tauri在高光条件下生长，仅存在较小的PSI级分。还发现两种PSI制备物缺乏远红叶绿素荧光（715- 730 nm），这是产氧光养生物中PSI的特征。O. tauri PSI可能反映了绿色植物中原始的捕光系统及其对海洋生态系统的适应。讨论了LHC超家族在光合真核生物中进化的可能影响。
Prasinophyceae are a broad class of early-branching eukaryotic green algae. These picophytoplankton are found ubiquitously throughout the ocean and contribute considerably to global carbon-fixation. Ostreococcus tauri, as the first sequenced prasinophyte, is a model species for studying the functional evolution of light-harvesting systems in photosynthetic eukaryotes. In this study we isolated and characterized O. tauri pigment–protein complexes. Two photosystem I (PSI) fractions were obtained by sucrose density gradient centrifugation in addition to free light-harvesting complex (LHC) fraction and photosystem II (PSII) core fractions. The smaller PSI fraction contains the PSI core proteins, LHCI, which are conserved in all green plants, Lhcp1, a prasinophyte-specific LHC protein, and the minor, monomeric LHCII proteins CP26 and CP29. The larger PSI fraction contained the same antenna proteins as the smaller, with the addition of Lhca6 and Lhcp2, and a 30% larger absorption cross-section. When O. tauri was grown under high-light conditions, only the smaller PSI fraction was present. The two PSI preparations were also found to be devoid of the far-red chlorophyll fluorescence (715–730nm), a signature of PSI in oxygenic phototrophs. These unique features of O. tauri PSI may reflect the primitive light-harvesting systems in green plants and their adaptation to marine ecosystems. Possible implications for the evolution of the LHC-superfamily in photosynthetic eukaryotes are discussed.