Genetic Regulation of Protochlorophyllide Reduction

该实验将分离和表征编码NADPH-原叶绿内酯氧化还原酶（PCR）的拟南芥基因。这似乎是一种核基因，其产物存在于未成熟的叶绿体（病变体）中。细胞中基因产物的水平是受光调节的，就像在叶绿体中发现的许多其他基因产物一样。该基因的一个新特征是，暴露在光线下，产物的数量会减少，而迄今为止研究的大多数其他光调节基因的表达都会在光线下增加。Timko将分离结构基因进行PCR，然后确定其序列和转录起始位点。他将使用植物DNA转化技术来定义基因的调控元件，包括光响应元件。该元件将用于分离和表征其响应的细胞因子。光对植物基因表达的调控一直是植物分子生物学研究的核心问题。拟议的工作将检查一个新的光调节基因的结构和调控；被光抑制的人：表情被光抑制的人该基因的产物在光诱导的叶绿体成熟过程中起着重要的作用。因此，这项工作将有助于我们对植物基因表达和叶绿体形态发生调控的理解。

The proposed experimentation will isolate and characterize the arabidopsis gene encoding NADPH- protochlorophyllide oxioreductase (PCR). This appears to be a nuclear gene whose product is found in immature chloroplasts (etioplasts). The level of gene product in the cell is light-regulated, as is that of a number of other gene products found in the chloroplast. A novel feature of this gene is that the amount of product is decreased by exposure to light, whereas expression of most other light-regulated genes so far studied is augmented by light. Timko will isolate the structural gene for PCR, then determine its sequence and the start sites for its transcription. He will use plant DNA transformation techniques to define the regulatory elements of the gene, including the photoresponsive element. The element will be used to isolate and characterize the cellular factor(s) to which it responds. The regulation of plant gene expression by light has been a central problem in plant molecular biology. The proposed work will examine the structure and regulation of a novel photoregulated gene; one whose expression appears to be inhibited by light. The gene's product acts at an important step in the light-induced maturation of the chloroplast. Thus, the proposed work should lead to a valuable increase in our understanding of the regulation of plant gene expression and of the morphogenesis of the chloroplast.