Translational Control of RuBPCase Gene Expression

9728547浆果/Gollnick Amaranth是一种双子叶植物，它利用高效的C4光合作用途径。在苋菜中，编码核酮糖1，5-二磷酸(RuBPCase)大亚基(LSU)和小亚基(SSU)的基因的表达受到光和发育过程的强烈调控。以前，已经证明LSU和SSU多肽的合成随着光照的变化而发生非常迅速的变化，并且这些变化是由于翻译/水平的调节。此外，rbcL和rbcs mRNAs的翻译变化与叶片光合作用能力的变化有关，似乎发生在叶片发育的不同阶段。将进行的研究将分析发生在rbcL基因5‘非编码区的光依赖的mRNA/蛋白质相互作用。两个47 kDa蛋白质的光依赖结合以及与加工的rbcL 5‘UTR序列形成的慢迁移凝胶迁移率位移复合体与我们观察到的RuBPCase LSU翻译的光诱导激活密切相关。为了更好地了解mRNA/蛋白质相互作用在调节这种叶绿体编码的光合多肽合成中的作用，我们将对主要的47 kDa rbcL 5‘UTRmRNA结合蛋白进行鉴定，并确定它们的相关因素。将研究由光生植物的叶绿体提取物产生的慢迁移rbcL 5‘UTRRNA结合复合体的形成和组成，以及由暗叶绿体提取物产生的快速迁移复合体的形成和组成。此外，还将确定rbcL 5‘UTR长度的处理差异如何防止或增强光依赖的蛋白质结合和复合体的形成。从长远来看，从这些深入的生化研究中获得的信息将被用来表征光依赖蛋白质/R NA相互作用的动力学性质，并利用转基因C4DICOT系统来确定RNA结合蛋白的作用。这些研究将为在翻译水平上调节C4双子叶苋属植物和其他高等植物中光合作用基因表达的机制提供新的见解。在高等植物中，光既是一种初级能源，也是一种调节生长的环境信号。对植物光调控反应的研究对于确定控制植物发育的因素如何对环境刺激做出反应具有重要意义。蛋白质的翻译过程是所有生物体基因表达总途径中不可或缺的一部分。特定mRNAs翻译的快速变化可能是一种适应突然的环境变化的机制，这种变化可能会影响生物体的生存。除了为光合作用的遗传控制提供独特的视角外，这项关于籽粒扬的基础研究还将有助于将其发展成为一种重要的农业作物，用于食品生产和工业。

9728547 Berry/Gollnick Amaranth is a dicotyledonous grain plant that uses the highly efficient c4 pathway of photosynthesis. In amaranth, the expression of genes encoding the large subunit (LSU, produced from the plastid-encoded rbcL gene) and small subunit (SSU, produced from nuclear-encoded rbcS genes) of ribulose 1,5-bisphosphate (RuBPCase) is strongly regulated by light and by developmental processes. Previously, it has been shown that very rapid changes in synthesis of the LSU and SSU polypeptides are induced in response to changes in illumination, and that these changes are due to regulation at the translations/level. In addition, alterations in translation from rbcL and RbcS mRNAs are associated with changes in leaf photosynthetic capacity, and appear to occur during various stages of leaf development. The research to be conducted will analyze light-dependent mRNA/protein interactions that occur at the 5' UTR of rbcL mRNA. The light-dependent binding of two 47 kDa proteins and the formation of a slow-migrating gel mobility shift complex to processed rbcL 5'UTR sequences are tightly associated with our observations of light-induced activation of RuBPCase LSU translation. To better understand the role of mRNA/protein interactions in regulating the synthesis of this plastid-encoded photosynthetic polypeptide, the predominant 47 kDa rbcL 5' UTR mRNA binding proteins will be characterized and their associated factors identified. The formation and composition of the slow-migrating rbcL 5' UTR RNA binding complex produced by plastid extracts from light-grown plants will be investigated, as will the fast-migrating complex produced by the dark-plastid extracts. In addition, it will be determined how processing differences in the length of the rbcL 5' UTR prevent or enhance light-dependent protein binding and complex formation. In the long term, the information acquired from these in depth biochemical studies will be used to characterize the kinetic properties of the light-dependent protein/R NA interactions, and to determine the role of the RNA binding proteins using a transgenic C4 dicot system. These investigations will provide novel insights into mechanisms that regulate photosynthetic gene expression at the translational level in the C4 dicot amaranth and other higher plants. In higher plants light serves both as a primary energy source and as an environmental signal that regulates development. Investigations into light-regulated responses in plants are of fundamental importance in determining how factors controlling plant development respond to environmental stimuli. The process of protein translation is an integral part of the overall pathway of gene expression in all organisms. Rapid changes in the translation of specific mRNAs may be a mechanism for adapting to sudden environmental changes that could affect the survival of the organism. In addition to providing unique perspectives about the genetic control of photosynthesis, this basic research with amaranth will aid in its development as an agriculturally important crop for food production and for industry.