PHOTOREGULATED GENE EXPRESSION

将对编码叶绿体蛋白的植物核基因进行研究 S 核酮糖-1，5-二磷酸羧基酶及其多肽成分 捕光的叶绿素a/b(CAB)复合体。顺式作用启动子 介导这些光调控基因转录调控的元件 基因将被详细描述。正在讨论的基因将包括 番茄的rbcs-3A基因、rbcs-1a基因fr M 拟南芥和白花烟草CAB-E基因 (烟草)。这些研究将通过构建嵌合基因来进行 含有RBC和CAB启动子的元件与报告基因融合。这些 启动子元件将在体外通过缺失和定点定向进行操作 突变。嵌合基因的表达将在 农杆菌介导法转化烟草获得转基因植株 。 与这些启动子元件结合的反式作用因子将进一步 特色化的。这将通过频带偏移分析、足迹、 D 蛋白质提纯。先前已证实的蛋白质的作用 调节因子与启动子元件结合的磷酸化将 被刻画出来。DNA序列和蛋白质因子的性质 我们将研究调节的昼夜和昼夜节律。 将对番茄和拟南芥的光响应突变体进行研究 确定它们是否缺乏任何单个红细胞或CAB基因的表达。一个 将在原生质体中开展瞬时表达分析，以期 促进顺式作用启动子元件的快速分析。所描述的 这两项研究都将有助于更好地理解 基因表达的转录调控，并将有助于 粮食作物营养品质检测新方法的发展 将会得到改善。

A study will be made of plant nuclear genes encoding the chloroplast protei s ribulose-1, 5-biphosphate carboxylase (RBCS) and the polypeptide components of the light-harvesting chlorophyll a/b (CAB) complex. Cis-acting promoter elements mediating the transcriptional regulation of these photoregulated genes will be characterized in detail. The genes in question will include the rbcs-3A gene from Lycopersicon esculentum (tomato), the rbcS-1A gene fr m Arabidopsis thaliana, and the cab-E gene from Nicotiana plumbaginifolia (tobacco). These studies will be carried out by constructing chimeric gene containing RBCS and CAB promoter elements fused to reporter genes. These promoter elements will be manipulated in vitro by deletion and site-directe mutation. The expression of the chimeric genes will be examined in transgenic tobacco plants generated by Agrobacterium-mediated transformatio . Trans-acting factors that bind to these promoter elements will be further characterized. This will be achieved by band-shift assays, footprinting, a d protein purification. A previously-demonstrated role for protein phosphorylation in modulating binding of factors to promoter elements will be characterized. The nature of the DNA sequences and protein factors that mediate diurnal and circadian expression rhythms will be examined. Photoresponse mutants in tomato and Arabidopsis will be examined in order t determine if they lack expression of any individual RBCS or CAB genes. A transient expression assay will be developed in protoplassts so as to facilitate a rapid analysis of cis-acting promoter elements. The described studies will both contribute to a better understanding of the complexities of transcriptional regulation of gene expression and will assist in the development of novel methods by which the nutritional quality of food crops will be improved.