Moleculargenetical analysis of phytochrome siggnal transduction

光敏色素信号转导的分子遗传学分析

• 批准号: 08454253
• 负责人: NAGATANI Akira
• 金额: $ 5.7万
• 依托单位: THE UNIVERSITY of TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 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-08454253/
• 关键词: phytochrome; photomorophogenesis; signal transduction; Arabidopsis; transgenic plants; nuclear localization; 植物; エンハンサー; タグ系統; 突然変異; 形質転換

Phytochrome is a chromoprotein, which is found in all green plants. Phytochrome is know to be act as a major photoreceptor mediating divergent plant responses to light. Although phytochrome has been studied intensively, molecular mechanism by which phytochrome transduce the light remains unknown. We addressed this problem with the aid of molecular genetical techniques. Two topics were pursued in this study. Firstly, activation-tagged Arabidopsis lines were produced and mutants that show deficiencies in light responses are isolated and analyzed. Secondly, nuclear localization of phytochrome B (phyB) was studied by using GFP as a fluorescent tag.Mutants that exhibit partial greening under dim light were isolated from the activation-tagged lines. Among them is a mutant, which resembles brassinolide-less mutants. The molecular analysis revealed that a novel cytochrome P450 gene is over-expressed in this mutant. We further confirmed that the gene is indeed responsible for the phenotypes by producing transgenic Arabidopsis lines over-expressing this gene. Unfortunately, the phenotype appeared to be related not only to phytochrome but also to other photoreceptors. Nevertheless, the gene will be a powerful tool to elucidate relationships between light and brassionsteroid signals.We examined intracellular localization of phyB by expressing a phyB-GEP fusion protein in the phyB deficient mutant of Arabidopsis. The results indicated that the introduced phyB-GFP is biologically active. Microscopic observation of the cells revealed that phyB-GFP localizes to the nucleue under light conditions. In contrast, phyB-GFP is distributed throughout the cell in darkness. Hence, phyB appears to translocate to the nucleus in a light-dependent manner. Although phytochrome has been believed to function in the cytoplasm, oure results suggest that the nucleus is one of the cellular compartments where the phytochrome action takes place

光敏色素是一种存在于所有绿色植物中的色素蛋白。光敏色素作为一种主要的光感受器，介导植物对光的不同反应。尽管光敏色素已被深入研究，但光敏色素对光的吸收的分子机制仍不清楚。我们借助分子遗传学技术解决了这个问题。本研究探讨了两个主题。首先，产生激活标记的拟南芥品系，并分离和分析显示光响应缺陷的突变体。其次，以绿色荧光蛋白（GFP）为荧光标记，对光敏色素B（phyB）的核定位进行了研究。其中有一种突变体，类似于无油菜素内酯的突变体。分子生物学分析表明，一个新的细胞色素P450基因在该突变体中过表达。我们通过产生过表达该基因的转基因拟南芥品系进一步证实了该基因确实对表型负责。不幸的是，这种表型似乎不仅与光敏色素有关，而且与其他光感受器有关。然而，该基因将是一个强有力的工具，阐明光和brassionsteroid signals.We之间的关系phyB细胞内定位的phyB-GEP融合蛋白在拟南芥的phyB缺陷突变体的表达。结果表明，phyB-GFP具有生物学活性。显微镜下观察发现phyB-GFP在光照条件下定位于细胞核。相反，phyB-GFP在黑暗中分布在整个细胞中。因此，phyB似乎以光依赖的方式易位到细胞核。虽然光敏色素被认为在细胞质中起作用，但我们的结果表明，细胞核是光敏色素作用发生的细胞区室之一

项目成果

Yamaguchi, R.et al.: "Light-dependent Translocation of a Phytochrome B-GFP Fusion Protein to the Nucleus in Transgenic Arabidopsis." J.Cell Biol.(in press).

Yamaguchi, R.et al.：“光敏色素 B-GFP 融合蛋白在转基因拟南芥中的细胞核的光依赖性易位”。

Nagatani,A: "Spatial Distribution of Phytochromes" J.Plant Res. 110. 123-130 (1997)

Nagatani，A：“光敏色素的空间分布”J.Plant Res。

Yamaguchi,R.他: "Light-dependent Translocation of a Phytochrome B-GFP Fusion Protein to the Nucleus in Transgenic Arabidopsis." J.Cell Biol.(1999)

Yamaguchi, R. 等人：“光敏色素 B-GFP 融合蛋白在转基因拟南芥中的细胞核的光依赖性易位”（J. Cell Biol）。