Modulation of chlorophyll synthesis and its effect on the biogenesis of two photosystems

叶绿素合成的调节及其对两个光系统生物发生的影响

• 批准号: 08836006
• 负责人: FUJITA Yuichi
• 金额: $ 1.54万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08836006/
• 关键词: chlorophyll; protochlorophyllide reductase; Plectonema boryanum; cyanobacterium; photosystem; Plectonema boryanum; 黄化; クロロフィル合成; 33-kD蛋白質; PsaC蛋白質; プロトクロロフィリド還元; 緑化

1. Physiological roles of the two protochlorophyllide reduction systemsCyanobacteria have two protochlorophyllide (Pchlide) reductases catalyzing the conversion of Pchlide to chlorophyllide, a key step in the biosynthetic pathway of chlorophyll (Chl) ; a light-dependent (LPOR) and a light-independent (DPOR) reductase. Gene (por) encoding LPOR has been cloned from Plectonema boryanum, and a por-disrupted mutant, YFP12, was isolated by target mutagenesis to compare phenotype of YFP12 with those of wild-type and a chlL-disrupted (DPOR-less) mutant, YFC2. YFP12 grew as well as wild type under low light conditions, but not under high light conditions (>130 mu E m^<-2>s^<-1>). In contrast, YFC2 was able to grow under both light conditions. These results suggested that, although both the reductases contributed to Chl synthesis in the cells growing in the light, LPOR was essential for the cells to grow under the high light intensity.2. Analysis of the construction of the photosystems under a limitation of Chl availability.YFC2 lacking DPOR was etiolated to reduce the Chl content less than 0.5% of the original level when this mutant was continued to grow under dark for a number of generations. Under this etiolating process, we analyzed the construction of two photosystems, PSI and PSII.Polypeptides of PSII,CP43 and 33 kDa subunit were contained at the level comparable to wild type, while those of PSI,PsaA/PsaB and PsaC were reduced an undetectable level by western analysis. This results suggested that the limitation of Chl supply resulted in the preferential degradation of PSI.

1. 两种原叶绿内酯还原系统的生理作用蓝藻细菌具有两种原叶绿内酯还原酶，可催化Pchlide转化为叶绿素内酯，这是叶绿素合成途径的关键步骤；一个依赖光的（lpoor）和一个不依赖光的（dpoor）还原酶。从boryanm Plectonema中克隆了编码LPOR的基因（por），并通过靶诱变分离出por中断的突变体YFP12，将其与野生型和无por中断的突变体YFC2的表型进行比较。YFP12在弱光条件下生长良好，但在强光条件下生长不佳（>30亩E m^<-2>s^<-1>）。相比之下，YFC2在两种光照条件下都能生长。这些结果表明，虽然这两种还原酶都有助于细胞在光照下的Chl合成，但LPOR对细胞在高光强下的生长至关重要。Chl有效度限制下光系统的构建分析。缺乏DPOR的突变体YFC2在黑暗环境下继续生长数代后，Chl含量降低到原始水平的0.5%以下。在此黄化过程中，我们分析了PSI和PSII两个光系统的构建。PSII、CP43和33 kDa亚基的多肽含量与野生型相当，而PSI、PsaA/PsaB和PsaC的多肽含量减少到western分析无法检测到的水平。结果表明，Chl供应的限制导致了PSI的优先降解。

项目成果

Y.Fujita: "Identification of the chlB gene and the gene product essential for the light-independent chlorophyll biosynthesis in the cyanobacterium Plectonema boryanum" Plant Cell Physiology. 37. 313-323 (1996)

Y.Fujita：“蓝藻 Plectonema boryanum 中不依赖于光的叶绿素生物合成所必需的 ChlB 基因和基因产物的鉴定”植物细胞生理学。

Y.Fujita: "Cloning of the gene encoding a protochlorophyllide reductase" Plant Cell Physiology. 39 (2). 177-185 (1998)

Y.Fujita：“编码原叶绿素还原酶的基因的克隆”植物细胞生理学。

Y.Fujita: "Protochlorophyllide reduction : a key step in the greening of plants" Plant Cell Physiology. 37. 411-421 (1996)

Y.Fujita：“原叶绿素内酯还原：植物绿化的关键步骤”植物细胞生理学。

Y.Fujita: "Protochlorophyllide reduction : a key step in the greening of plants" Plant and Cell Physiology. 37巻4号. 411-421 (1996)

Y. Fujita：“原叶绿素减少：植物绿化的关键步骤”《植物和细胞生理学》，第 37 卷，第 411-421 期（1996 年）。

Y.Fujita: "Cloning of the gene encoding a protochlorophyllide reductase" Plant Cell Physiology. 39(2). 177-185 (1998)

Y.Fujita：“编码原叶绿素还原酶的基因的克隆”植物细胞生理学。