Developmental Regulation of Ferredoxin Gene Expression

9507396汤普森这个项目涉及FED-L，一个编码叶绿体铁氧还蛋白的核基因在高等植物叶片中的表达。无论是暗生长的幼苗还是绿色植物的光合作用叶片，Fed-L基因的表达都是对光照的响应。然而，绿叶的反应机制与大多数其他植物基因典型的启动子介导的转录反应有很大的不同。以前的工作主要集中在绿叶的反应上，并在转录单位中发现了一个内部光反应元件(ILRE)。位于编码区的未翻译前导和5‘部分的序列对于iLRE功能是必不可少的，并且在编码区的这一部分需要开放阅读框架。这些观察结果支持这样的假设，即光效应是通过翻译依赖于mRNA稳定性的变化来调节的。这种机制在植物中的研究才刚刚开始，但很可能具有相当重要的意义。实验旨在提供有关iLRE功能序列要求的额外信息，并验证FED-L光反应涉及mRNA运输和/或降解的变化的假设。ILRE的组成部分将在核苷酸水平上定义，并将测试额外的无意义密码子插入，以确定开放阅读框架是否必须延伸到编码区的全长。化学诱导和阻抑启动子将被用来在没有抑制剂的情况下测定FED-L基因在体内的半衰期，并测试光对核内和细胞质内基因积累动力学的影响。我们的实验将为未来的研究提供基础，包括对影响FED-L表达的突变进行遗传分析，并将帮助我们实现定义调节这种重要光合蛋白产生的一整套事件和因素的长期目标。本项目涉及编码叶绿体铁氧还蛋白的核基因FED-L在高等植物叶片中的表达。无论是暗生长的幼苗还是绿色植物的光合作用叶片，Fed-L基因的表达都是对光照的响应。这项研究将探讨光效应是由翻译依赖的mRNA稳定性变化所介导的假说。这种机制在植物中的研究才刚刚开始，但很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，包括对影响FED-L表达的突变进行遗传分析，并将帮助我们实现定义调节这种重要光合蛋白产生的一整套事件和因素的长期目标。***

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. ***