Molecular Analysis of the rbcS Multigene Family

本项目将研究核酮糖小亚基（SSU）多基因家族成员差异表达的分子机制。1、5。二磷酸羧化酶（rbc基因）以番茄为模型系统。番茄有5个红细胞基因。1,红血球。2,红血球。3A和红细胞。3C，即编码三个iso。变异的SSU蛋白。这五种红细胞基因在子叶、叶和果实中有差异转录。在具有相似发育和器官的5个番茄红细胞基因中，有几个功能不明确的5′DNA序列是保守的。特定的表达模式。此外，来自单个番茄红细胞基因的mrna在不同组织中积累的水平有很大的不同，但这种模式并没有反映在三个iso的积累中。变异的SSU蛋白。我们将逐一检查红细胞。作用DNA区域来定义它们在发育和器官中的作用。特定的。转录失控并检查它们如何相互作用。我们将识别蛋白质。通过DNasel足迹分析来确定红细胞基因的差异转录是否与5' DNA片段的DNA蛋白结合模式的差异相关。这将补充我们对cis的分析。转基因植物的作用DNA序列及瞬时测定。此外，转录运行。分析和定量杂交将用于评估五种红细胞基因的转录调节在多大程度上建立其mrna的相对水平。在翻译水平上，我们将测试红细胞5'非翻译区长度的变化是否会导致iso的差异积累。变异的SSU蛋白。为了进一步了解不同红细胞表达在水果中的作用，我们将利用一种水果。产生反义的特定启动子。RNA来阻断红细胞。1和红细胞。2 表达式。最后，我们将激活通常不活跃的红细胞。3A基因产生iso。以确定这对器官发育有什么影响，如果有的话。发育、器官。在高等植物叶绿体中，转录和翻译的特异性和光依赖性调控是编码光合蛋白的核基因表达的重要控制步骤。这项研究的结果应该为这些过程提供更深入的见解。

This project will investigate the molecular mechanism involved in the differential expression of the multigene family members for the small subunit (SSU) of ribulose.1, 5.bisphosphate carboxylase (rbcS genes) using tomato as a model system. Tomato has five rbcs genes rbcS.1, rbcS.2, rbcS.3A and rbcS.3C, which encode three iso.variant SSU proteins. The five rbcS genes are differentially transcribed in cotyledons, leaves and fruit. Several 5' DNA sequences which are functionally undefined are conserved among the five tomato rbcS genes which share similar developmental and organ.specific expression pattern. In addition, mRNAs from the individual tomato rbcS genes accumulate to substantially different levels in different tissues, but this pattern is not reflected in the accumulation of the three iso. variant SSU proteins. We will examine rbcS cis.acting DNA regions to define their role in the developmental and organ. specific on.off control of transcription and examine how they interact. We will identify protein.binding domains by DNasel footprint analysis to determine if the differential transcription of the rbcS genes is correlated with differences in the DNA: protein binding pattern of 5' DNA fragments. This will complement our analysis of cis.acting DNA sequences in transgenic plants and transient assays. Furthermore, transcription run.on assays and quantitative hybridizations will be used to assess the extent to which transcriptional regulation of the five rbcS genes establishes the relative levels of their mRNAs. At the translational level, we will test if variations in the length of the rbcS 5' untranslated regions result in the differential accumulation of iso.variant SSU proteins. To attain further information on the role of differential rbcS express in fruit, we will take advantage of a fruit.specific promoter for the production of antisense.RNA to block rbcS.1 and rbcS.2 expression. Finally, we will activate the normally inactive rbcS.3A gene to produce the iso.variant 3 SSU protein in fruit to determine what effect, if any, this has on organ development. Developmental, organ.specific and light.dependent regulation of transcription and translation are important control steps in the expression of nuclear genes encoding photosynthetic proteins found in the chloroplasts of higher plants. The results of this study should provide greater insights into those processes.