Functional analysis of N-terminal domains of Arabidopsis chlorophyllide a oxygenase
Functional analysis of N-terminal domains of Arabidopsis chlorophyllide a oxygenase
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DOI：
10.1016/j.plaphy.2007.07.016
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发表时间：
2007-10-01
影响因子：
6.5
通讯作者：
Tanaka, Ayumi
中科院分区：
文献类型：
--
作者：
Sakuraba, Yasuhito;Yamasato, Akihiro;Tanaka, Ayumi
高等植物通过改变捕光系统的触角大小来适应各种光环境。光系统的触角大小部分取决于捕光复合物中叶绿素B的量。叶绿素a加氧酶（CAO）通过两步氧化反应将叶绿素a转化为叶绿素B。在我们以前的研究中，我们证明了CAO蛋白的细胞水平控制叶绿素B的积累。我们发现高等植物CAO的氨基酸序列由三个结构域（A、B和C结构域）组成。C结构域具有催化功能，我们证明了A和B结构域的组合调节CAO的细胞水平。然而，A和B结构域各自的功能尚未确定。因此，在本研究中，我们构建了一系列删除的CAO序列，融合绿色荧光蛋白，并在拟南芥叶绿素b-少突变体chI-I中过表达，以进一步剖析A和B结构域的功能。随后对过表达含B结构域蛋白的转基因植物和缺乏B结构域的转基因植物进行比较分析，确定CAO蛋白水平没有显著差异。这些结果表明B结构域不参与CAO蛋白水平的调节。综上所述，我们得出结论，A结构域单独参与CAO蛋白水平的调节机制。(C)2007年，Elsevier Masson SAS。All rights reserved.
Higher plants acclimate to various light environments by changing the antenna size of a light-harvesting photosystem. The antenna size of a photosystem is partly determined by the amount of chlorophyll b in the light-harvesting complexes. Chlorophyllide a oxygenase (CAO) converts chlorophyll a to chlorophyll b in a two-step oxygenation reaction. In our previous study, we demonstrated that the cellular level of the CAO protein controls accumulation of chlorophyll b. We found that the amino acids sequences of CAO in higher plants consist of three domains (A, B, and C domains). The C domain exhibits a catalytic function, and we demonstrated that the combination of the A and B domains regulates the cellular level of CAO. However, the individual function of each of A and B domain has not been determined yet. Therefore, in the present study we constructed a series of deleted CAO sequences that were fused with green fluorescent protein and overexpressed in a chlorophyll b-less mutant of Arabidopsis thaliana, chI-I, to further dissect functions of A and B domains. Subsequent comparative analyses of the transgenic plants overexpressing B domain containing proteins and those lacking the B domain determined that there was no significant difference in CAO protein levels. These results indicate that the B domain is not involved in the regulation of the CAO protein levels. Taken together, we concluded that the A domain alone is involved in the regulatory mechanism of the CAO protein levels. (C) 2007 Elsevier Masson SAS. All rights reserved.