PHOTOREGULATED GENE EXPRESSION

对编码叶绿体蛋白质的植物核基因进行了研究， S 核酮糖-1，5-二磷酸羧化酶（RBCS）和多肽组分 光捕获叶绿素a/B（CA B）复合物。 顺式作用启动子 元件介导这些光调节的转录调节 基因将被详细描述。 这些基因包括 番茄rbcs-3A基因、番茄rbcS-1A M 拟南芥和烟草的cab-E基因 （烟草）。 这些研究将通过构建嵌合基因进行 含有与报告基因融合的RBCS和CAB启动子元件。 这些 启动子元件将在体外通过缺失和定点突变来操纵， 突变 嵌合基因的表达将在 通过农杆菌介导的转化获得转基因烟草植株 . 与这些启动子元件结合的反式作用因子将被进一步研究。 表征了 这将通过带移分析、足迹法、 D 蛋白质纯化 蛋白质的一个先前被证明的作用 调节因子与启动子元件结合的磷酸化作用将 被定性。 DNA序列和蛋白质因子的性质， 将检查中间的昼夜和昼夜表达节律。 番茄和拟南芥中的光响应突变体将被检测， 确定它们是否缺乏任何单个RBCS或CAB基因的表达。 一 将在原生质体中开发瞬时表达测定法， 有助于顺式作用启动子元件的快速分析。 所描述的 研究将有助于更好地理解 基因表达的转录调控，并将有助于 开发新的方法， 将得到改善。

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.