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; 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。两个原纤维化脂质物还原系统的生理作用，具有两个原氯地叶（Pchlide）还原酶，可催化Pchlide向叶绿素的转化，这是叶绿素生物合成途径的关键步骤，光依赖性（LPOR）和一个独立的（DPOR）还原酶。编码LPOR的基因（POR）已从boryanum中克隆，并通过靶诱变分离出POR中断的突变体YFP12，以比较YFP12的表型与野生型的表型与野生型的表型和无用的（Dpor-Distresped（Dpor-Dpor）突变体YFC2。 YFP12在低光条件下的生长和野生型增长，但在高光条件下不变（> 130 mu e m^<-2> s^<-1>）。相反，YFC2能够在两个光条件下生长。这些结果表明，尽管两种还原酶促进了在光中生长的细胞中CHL合成的作用，但LPOR对于细胞在高光强度下生长至关重要。2。在CHL可用性的限制下，对光系统的构建进行分析。缺少DPOR的YFC2被置为降低CHL含量小于原始水平的0.5％时，当该突变体在黑暗下继续生长多代时。在这个构化过程中，我们分析了PSII，PSII和PSII的两个光系统的构建。PSII，CP43和33 kDa亚基在与野生型相当的水平上包含，而PSI，PSAA/PSAA/PSAB和PSAC的含量则降低了不可能的水平。该结果表明，CHL供应的局限性导致PSI的优先降解。