REGULATION OF CHLOROPHYLL-APOPROTEIN SYNTHESIS

这项研究的长期目标是定义生化机制。 它调节着叶绿素的合成和组装， 载脂蛋白。第一个具体目标是阐明d1的合成是如何进行的。 受叶绿素α和一个核基因的调控，该基因在 大麦突变体Vir115。D1是一种叶绿素-载脂蛋白，它与 D2，结合叶绿素、叶绿素和苯二酚。这种异二聚体形成了 光系统II的反应中心，一个大的蛋白质复合体，介导 叶绿体中氧的释放和叶绿体中的苯二酚还原。D1不会 在缺乏叶绿素的黑暗生长的植物中积累。然而，mRNA3 编码这种蛋白质与多聚体和翻译有关 在脉冲标记的黄体中可以检测到中间体。D1累积 当植物被照亮时，叶绿素就会合成。此数据 建议通过在d1中携带步骤来分析叶绿素结合。 翻译、转位到膜和叶绿素结合将是 通过执行几个具体目标进行分析；(1)在d1中的早期步骤 翻译将使用脚印分析来识别核糖体 结合部位，(2)膜结合的D1翻译的性质 中间体将使用脉冲追逐分析进行研究，以确定是否 中间体与多聚体相关，并通过测定 膜多聚体中PSBA基因的核糖体分布，(3) 我们将研究D1在类囊体膜中的转移，以及 研究了转位和叶绿素结合的协调性，(4) 将检测D1的蛋白水解性和核编码的作用 蛋白质在D1合成中鉴定，(5)通过研究获得知识 将扩展到对另外三个Chl-载脂蛋白的分析 (CP47，P700 chl-载脂蛋白)。此外，蓝色通过哪些机制 光对psbD-PSBC RNA种群的调节将被研究；1. 转录和RNA稳定性对光诱导的影响 两个psbD-PSBC RNA的积累将被量化，2.哪些因素 刺激pSBD-pSBC转录将被鉴定和3.蓝光 可诱导的核基因编码调节psbD-D的胞体蛋白。 PSBC表达将被分离。

The long range goal of this research is to define biochemical mechanisms which regulate the synthesis and assembly of chlorophyll and chlorophyll- apoproteins. The first specific aim is to elucidate how D1 synthesis is regulated by chlorophyll alpha and a nuclear gene which is disrupted in the barley mutant vir115. D1 is a chlorophyll-apoprotein which, together with D2, binds pheophytin, chlorophyll and quinones. This heterodimer forms the reaction center of Photosystem II, a large protein complex which mediates oxygen evolution and plastoquinone reduction in chloroplasts. D1 does not accumulate in dark-grown plants which lack chlorophyll. However, mRNA encoding this protein is associated with polysomes and translation intermediates can be detected in pulse-labeled etioplasts. D1 accumulates when plants are illuminated and chlorophyll is synthesized. This data suggests that chlorophyll binding will be analyzed by carrying steps in D1 translation, translocation into membranes and chlorophyll binding will be analyzed by carrying out several specific objectives; (1) Early steps in D1 translation will be analyzed using toeprint assays to identify ribosome binding sites, (2) The nature of membrane bound D1 translation intermediates will be investigated using pulse-chase assays, determining if the intermediates are associated with polysomes and by determining the distribution of ribosomes on psbA mRNA found in membrane polysomes, (3) Translocation of D1 into thylakoid membranes will be studied and the coordination of translocation and chlorophyll-binding investigated, (4) Proteolysis of D1 will be examined and the role of a nuclear encoded protein in D1 synthesis identified, (5) Knowledge gained through the study of D1 will be extended to the analysis of three additional chl-apoproteins (CP47, P700 chl-apoproteins). In addition, the mechanisms by which blue light regulates the psbD-psbC RNA population will be studied; 1. The influence of transcription and RNA stability on the light-induced accumulation of two psbD-psbC RNAs will be quantitated, 2. Factors which stimulate psbD-psbC transcription will be identified and 3. Blue light inducible nuclear genes which encode the plastid proteins regulating psbD- psbC expression will be isolated.