Developmental Regulation of Ferredoxin Gene Expression

9507396 Thompson本项目涉及高等植物叶片中编码叶绿体铁氧还蛋白的核基因Fed-l的表达。 在黑暗生长的幼苗和绿色植物的光合作用叶片中，Fed-l mRNA响应于光照而积累。然而，在绿色叶的反应机制显着不同的启动子介导的转录反应的典型的大多数其他植物基因。以前的工作主要集中在绿色叶片的反应，并确定了一个内部的光响应元件（iLRE）的转录单位。位于编码区的非翻译前导区和5'部分的序列对于iLRE功能是必需的，并且在编码区的该部分中需要开放阅读框。这些观察结果支持的假设，即光效应介导的mRNA稳定性的变化依赖于光照。 这种机制在植物中的研究才刚刚开始，但可能具有相当重要的意义。 设计实验以提供关于iLRE功能的序列要求的额外信息，并测试Fed-I光响应涉及mRNA转运和/或降解的变化的假设。将在核苷酸水平上定义iLRE的组分，并检测额外的无义密码子插入，以确定开放阅读框是否必须延伸至编码区的全长。 将使用化学诱导型和阻遏型启动子来确定在不存在抑制剂的情况下Fed-I mRNA的体内半衰期，并测试光对细胞核和细胞质区室中mRNA积累的动力学的影响。我们的实验将为未来的研究提供基础，包括影响Fed-I表达的突变的遗传分析，并将帮助我们实现我们的长期目标，即定义调节这种重要光合蛋白产生的整个事件和因素。 本课题研究叶绿体铁氧还蛋白基因Fed-l在高等植物叶片中的表达。 在黑暗生长的幼苗和绿色植物的光合作用叶片中，Fed-l mRNA响应于光照而积累。本研究将探讨的假设，光效应介导的mRNA稳定性的变化依赖于光照。 这种机制在植物中的研究才刚刚开始，但可能具有相当重要的意义。 我们的实验将为未来的研究提供基础，包括影响Fed-I表达的突变的遗传分析，并将帮助我们实现我们的长期目标，即定义调节这种重要光合蛋白产生的整个事件和因素。 ***

9507396 Thompson This project concerns the expression of Fed-l, a nuclear gene encoding chloroplast ferredoxin in higher plant leaves. Fed-l mRNA accumulates in response to illumination, both in dark-grown seedlings and in photosynthesizing leaves of green plants. However, the response mechanism in green leaves differs dramatically from the promoter-mediated transcriptional responses typical of most other plant genes. Previous work has focused on the response in green leaves and identified an internal light response element (iLRE) within the transcription unit. Sequences located both in the untranslated leader and in the 5' portion of the coding region are essential for iLRE function, and an open reading frame is required in this portion of the coding region. These observations support the hypothesis that light effects are mediated by translation-dependent changes in mRNA stability. Such mechanisms are only beginning to be studied in plants, but are likely to be of considerable importance. Experiments are designed to provide additional information about the sequence requirements for iLRE function, and to test the hypothesis that the Fed-l light response involves changes in mRNA transport and/or degradation. Components of the iLRE will be defined at the nucleotide level and additional nonsense codon insertions will be tested in order to determine whether an open reading frame must extend over the full length of the coding region. Chemically inducible and repressible promoters will be used to determine the in vivo half life of Fed-l mRNA in the absence of inhibitors and to test for light effects on the kinetics of mRNA accumulation in nuclear and cytoplasmic compartments. Our experiments will provide a basis for future investigations, including a genetic analysis of mutations affecting Fed-l expression, and will help us reach our long term goal of defining the entire set of events and factors that regulate production of this important photosynthetic protein. %%% This project concerns the e xpression of Fed-l, a nuclear gene encoding chloroplast ferredoxin in higher plant leaves. Fed-l mRNA accumulates in response to illumination, both in dark-grown seedlings and in photosynthesizing leaves of green plants. This research will investigate the hypothesis that light effects are mediated by translation-dependent changes in mRNA stability. Such mechanisms are only beginning to be studied in plants, but are likely to be of considerable importance. Our experiments will provide a basis for future investigations, including a genetic analysis of mutations affecting Fed-l expression, and will help us reach our long term goal of defining the entire set of events and factors that regulate production of this important photosynthetic protein. ***