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Regulation of electron transport at photosystem II

光系统 II 电子传输的调节

基本信息

批准号：
04453167
负责人：
TOYOSHIMA Yoshinori
金额：
$ 4.74万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04453167/
关键词：
Photosystem II QA Lprotein Photoinhibition Chloroplast Light-responsive promoter psbD C gene cluster DNA-binding protein psbD 光合成電子伝達 psbC 転写制御 Q_A L蛋白質

项目摘要

We examined the two major mechanisms by which balance of photosystem I (PSI) and Photosystem II (PSII) in the photosynthetic electron transport in higher plants was regulated in response to the variation of light environment, focusing on the regulation at PSII.1.Regulation of electron transport at primary quinone acceptor (QA) L protein which is a component of PSII complex and encoded by chloroplast psbL gene was found to be involved in the regulation of electron transport at QA site by in vitro reconstitution experiments. Plastoquinone-9 (PQ-9) depleted PSII reaction center core complex, consisting of CP47/D1/D2/Cytb-559/I proteins was isolated and submitted to the reconstitution with PQ-9. Only when the reconstitution was carried out with the L protein, PQ-9 reinserted in the complex and worked as QA in the resulting complex. Recombinant L protein was successfully over expressed in E.coli.and found to stand for the isolated L protein from PSII particles. Based on these findings, the … More molecular mechanism of the regulation of electron transport at QA site is being examined by the in vitro reconstitution with various types of mutant L protein.2.Regulation of the gene expression of psbC and psbD by light at transcription level There are two light-responsive promoters in chloroplast psbD/C gene cluster which encodes several important proteins of PSII.One (D/C-3 promoter) produces mRNA for D2 protein and the other (D/C-4 promoter) does that for CP43 protein. Upon light illumination, the former is reversibly activated while the latter is inactivated, respectively, suggesting that synthesis of these two proteins responses to light intensity through the regulation of activities of these promoters. We succeeded in the patrial purification of a nuclear-encoded regulatory factor which specifically activates the D/C-3 promoter. This factor seems to be a sequence specific DNA binding protein which recognizes the cis-element residing upstream region of the D/C-3 transcription initiation site. Less

本文研究了高等植物光合电子传递中光系统I （PSI）和光系统II （PSII）平衡响应光环境变化的两种主要机制，重点研究了光系统I （PSII）的调节。通过体外重组实验发现，由叶绿体psbL基因编码的初级醌受体（primary quinone receptor， QA） L蛋白参与调控QA位点的电子传递。PQ-9 （plasoquinone -9, PQ-9）贫PSII反应中心核心复合物，由CP47/D1/D2/ cypb -559/I蛋白组成，经PQ-9重组。只有当用L蛋白进行重组时，PQ-9才重新插入到复合体中，并在得到的复合体中作为QA。重组L蛋白在大肠杆菌中成功过表达，与PSII颗粒分离得到的L蛋白一致。在此基础上，通过对不同突变型L蛋白的体外重组，进一步探讨了QA位点电子传递调控的分子机制。光在转录水平上调控psbC和psbD基因的表达在叶绿体psbD/C基因簇中有两个光响应启动子，它们编码PSII的几个重要蛋白。一个（D/C-3启动子）产生D2蛋白的mRNA，另一个（D/C-4启动子）产生CP43蛋白的mRNA。在光照下，前者被可逆激活，而后者被灭活，这表明这两种蛋白的合成是通过调节这两种启动子的活性来响应光强的。我们成功地纯化了一个核编码的调节因子，它可以特异性地激活D/C-3启动子。该因子似乎是一种序列特异性的DNA结合蛋白，可识别位于D/C-3转录起始位点上游区域的顺式元件。少