Regulation of Differential mRNA Stability in Plastids

差异表达基因稳定性的调控是叶绿体基因表达的重要调控步骤。Gruissem博士已经证明，核糖体结合和mRNA中的结构是叶绿体mRNAs衰变的重要决定因素。叶绿体mRNAs 3‘端非翻译区的反向重复序列(IR-RNAs)是决定mRNA3’末端加工和稳定性的顺式调控因子，并与RNA结合蛋白相互作用。其中三个RNA结合蛋白已被纯化和测序，并克隆了这些蛋白的基因。已经鉴定并部分纯化了两种RNA结合蛋白，它们与一种mRNA的3‘IR-RNA特异地相互作用。建议利用体外重组系统，通过对拟南芥中RNA结合蛋白基因表达的遗传干扰，继续对叶绿体mRNA代谢和稳定性中的RNA结合蛋白进行功能分析。提出了一种生化和分子方法来确定核糖体相互作用如何影响叶绿体mRNAs的不同半衰期。对叶绿体基因稳定的分子机制的剖析将为细胞器基因表达的核控制提供新的和一般性的信息。在几乎所有生物体中，调控mRNA的加工和稳定性是控制基因表达的重要机制。尽管信使核糖核酸的稳定性调控广泛存在，但我们对这类调控的理解仍然是模糊和不完整的。

Regulation of differential mRNA stability is an important control step in plastid gene expression. Dr. Gruissem has shown that ribosome association and structures in the mRNA are important determinants for the decay of chloroplast mRNAs. Inverted repeat sequences (IR-RNAs) in the 3' untranslated region of chloroplast mRNAs function as cis-regulatory determinants for mRNA 3' end processing and stability , and interact with RNA-binding proteins. Three of the RNA-binding proteins have been purified and sequenced and the gene for the proteins has been cloned. Two RNA-binding proteins have been identified and partially purified that specifically interact with the 3' IR-RNA of one mRNA. It is proposed to continue the functional analysis of the RNA-binding proteins in chloroplast mRNA metabolism and stability using in vitro reconstituted systems, and by genetic interference of the expression of their genes in Arabidopsis. A biochemical and molecular approach is presented to determine how ribosome association contributes to the different half-lives of chloroplast mRNAs. %%% Dissection of the molecular mechanisms by which chloroplast mRNA stability is accomplished will provide novel and general information about the nuclear control of organelle gene expression. Regulation of mRNA processing and stability is an important mechanism in control of gene expression in virtually all organisms. Despite the wide-spread occurrence of mRNA stability control, our understanding of this type of regulation is still cryptic and incomplete.//