Characterization of photosystem II assembly complexes containing ONE-HELIX PROTEIN1 in Arabidopsis thaliana
Characterization of photosystem II assembly complexes containing ONE-HELIX PROTEIN1 in Arabidopsis thaliana
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DOI：
10.1007/s10265-022-01376-x
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发表时间：
2022-02
影响因子：
2.8
通讯作者：
Hanaki Maeda;Koharu Takahashi;Y. Ueno;Kei Sakata;Akari Yokoyama;Kozue Yarimizu;F. Myouga;K. Shinozaki;Shin-ichiro Ozawa;Yuichiro Takahashi;A. Tanaka;Hisashi Ito;S. Akimoto;Atsushi Takabayashi;R. Tanaka
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作者：
Hanaki Maeda;Koharu Takahashi;Y. Ueno;Kei Sakata;Akari Yokoyama;Kozue Yarimizu;F. Myouga;K. Shinozaki;Shin-ichiro Ozawa;Yuichiro Takahashi;A. Tanaka;Hisashi Ito;S. Akimoto;Atsushi Takabayashi;R. Tanaka
光系统II(PSII)的组装过程需要几个辅助蛋白质形成组装中间体。在植物中，早期组装中间产物包括PSII的D1和D2亚基以及一些辅助蛋白，包括至少一个螺旋蛋白1(OHP1)、OHP2和高叶绿素荧光244(HCF244)蛋白。在这里，我们报告了从高表达标记的OHP1蛋白的拟南芥转基因植物中纯化的组装中间体的基本特征，并将其命名为OHP1复合体。我们对OHP1复合体的两种主要形式进行了质谱分析，结果表明，除了PSII亚基D1、D2和细胞色素b559外，OHP1、OHP2和HCF244还含有OHP1、OHP2和HCF244。叶绿素荧光分析表明，该络合物的主要形式与叶绿素和类胡萝卜素结合，并以420微微秒的时间常数猝灭。为了确定辅助蛋白的定位，我们用洋地黄素衍生物糖苷元溶解类囊体膜，通过超速离心法将它们分离成三个组分，并在含有基质片层和基粒边缘的松散颗粒中与两种叶绿素生物合成酶一起检测到这些蛋白。结果表明，叶绿素的生物合成和组装可能发生在类囊体膜的同一隔室中。在弱光条件下，OHP2mRNA的诱导抑制显著降低了OHP2蛋白的表达，但对PSII的最大量子效率没有显著影响，但在强光条件下，OHP2蛋白的表达受到抑制。这意味着辅助蛋白是适应高光条件所必需的。
The assembly process of photosystem II (PSII) requires several auxiliary proteins to form assembly intermediates. In plants, early assembly intermediates comprise D1 and D2 subunits of PSII together with a few auxiliary proteins including at least ONE-HELIX PROTEIN1 (OHP1), OHP2, and HIGH-CHLOROPHYLL FLUORESCENCE 244 (HCF244) proteins. Herein, we report the basic characterization of the assembling intermediates, which we purified from Arabidopsis transgenic plants overexpressing a tagged OHP1 protein and named the OHP1 complexes. We analyzed two major forms of OHP1 complexes by mass spectrometry, which revealed that the complexes consist of OHP1, OHP2, and HCF244 in addition to the PSII subunits D1, D2, and cytochromeb559. Analysis of chlorophyll fluorescence showed that a major form of the complex binds chlorophyllaand carotenoids and performs quenching with a time constant of 420 ps. To identify the localization of the auxiliary proteins, we solubilized thylakoid membranes using a digitonin derivative, glycodiosgenin, and separated them into three fractions by ultracentrifugation, and detected these proteins in the loose pellet containing the stroma lamellae and the grana margins together with two chlorophyll biosynthesis enzymes. The results indicated that chlorophyll biosynthesis and assembly may take place in the same compartments of thylakoid membranes. Inducible suppression of theOHP2mRNA substantially decreased the OHP2 protein in mature Arabidopsis leaves without a significant reduction in the maximum quantum yield of PSII under low-light conditions, but it compromised the yields under high-light conditions. This implies that the auxiliary protein is required for acclimation to high-light conditions.