Posttranscriptional Regulation of Chloroplast Gene Expression

本研究从转录后水平分析光对RuBPCase大亚基(LSU)基因表达的调控。主要重点包括无细胞提取物中叶绿体蛋白质合成的分子和生化分析。发生在黑暗中的植物伸长的叶绿体转录表达正在进行体内研究，以确定核糖体运输时间是如何变化的，并在体外研究导致暗移植物与光生长植物中伸长率变化的因素(S)。最初的努力包括继续开发一种来自叶绿体的蛋白质合成提取物，这种提取物可以通过外源添加的mRNA进行编程。嵌合的LSU-CAT报告基因将用于建立该方法。调控叶绿体DNA编码基因的表达是理解高等植物生长发育的一个基本问题。这项建议中的研究着眼于通过发展一种无细胞系统来调节叶绿体基因表达的机制，该系统对完整叶绿体中发现的相同因素做出反应。这种分析方法的开发将显著提高这一领域的工作者解决与叶绿体蛋白质合成控制有关的问题的能力。

This research is analyzing the light-mediated control of expression of the RuBPCase large subunit (LSU) gene at the post-transcriptional level. The primary emphasis involves molecular and biochemical analyses of chlorplast protein synthesis in cell-free extracts. The chloroplast transcriptioanl repressionof elongation which occurs in plants shifted into darkness is being studied both in vivo, to determine how ribosomal transit times vary, and in vitro, to characterize factor(s) responsible for the altered elongation rates in dark-shifted versus light-grown plants. Initial efforts involve the continued development of a chloroplast-derived, protein synthesizing extract that is programable with exogenously added mRNA. The chimeric LSU- CAT reporter gene will be employed in developing this assay. TAhe regulation of expression of genes coded by chloroplast DNA is a fundamental problem associated with understanding growth and development in higher plants. The research in this proposal is looking at the mechanisms of regulation of chloroplast gene expression through the development of a cell-free system that responds to the same factors found in the intact chloroplast. The development of such an assay will markedly enhance the ability of workers in this field to address issues related to the control of chloroplast protein synthesis.***//