Chloroplast RNA Editing in Maize

该项目旨在更多地了解蛋白质是如何从植物基因中表达的。 在DNA被转录成RNA之后，RNA分子通常在形成信使RNA之前被进一步加工，信使RNA是指定将从基因中编码的指令合成的蛋白质的分子。 RNA编辑是RNA加工的一种类型。 在植物叶绿体（植物细胞中负责光合作用的细胞器）中，从叶绿体基因转录的RNA通过将一个核苷酸（“C”）修饰成另一个核苷酸（“U”）而改变。 从C到U的变化改变了RNA编码的氨基酸，并改变了蛋白质的组成。 在叶绿体中，RNA编辑是一种纠正基因错误的方法，这些错误会阻止功能性叶绿体蛋白的产生。 没有适当的RNA编辑的植物将无法茁壮成长。 RNA编辑也发生在微生物和动物中，这一过程对于重要蛋白质的合成至关重要。 已知玉米叶绿体经历28种不同的C-to-U编辑事件。 然而，进行叶绿体RNA编辑的酶或蛋白质尚未被鉴定。 此外，还不知道为什么选择一个C转化为U，而大多数Cs保持不变。 当提供有叶绿体RNA时能够进行编辑的玉米提取物将用于研究RNA的特征，所述特征对于识别适当的C编辑靶标是必不可少的。 玉米提取物也将被分馏，以了解更多关于将C转化为U的分子。 这些研究将利用包含玉米核和叶绿体基因组序列、玉米叶绿体蛋白质序列数据以及通过NSF支持的项目生成的玉米突变体集合的数据库。 体外编辑提取物的开发将对编辑界产生广泛的影响。 该项目将在若干级别提供培训机会，并让代表人数不足的少数群体参与。

This project seeks to learn more about how proteins are expressed from genes in plants. After DNA is transcribed into RNA, the RNA molecules are often further processed before they form messenger RNA, the molecule that specifies the protein that will be synthesized from the instructions that were coded in a gene. One type of RNA processing is RNA editing. In plant chloroplasts, the organelle in plant cells that is responsible for photosynthesis, RNAs transcribed from chloroplast genes are altered by the modifying of one nucleotide ("C") into another ("U"). The change from C to U alters the amino acid encoded by the RNA, and changes the composition of the protein that is made. In chloroplasts, RNA editing is a way to correct mistakes in the genes that would prevent production of functional chloroplast proteins. Plants without proper RNA editing would fail to thrive. RNA editing also occurs in microrganisms and animals, where the process is essential for synthesis of important proteins. Maize chloroplasts are known to undergo 28 different C-to-U editing events. However, none of the enzymes or proteins that carry out chloroplast RNA editing have yet been identified. Furthermore, it is not known why one C is selected for conversion to U, while most Cs remain unaltered. Maize extracts capable of carrying out editing when provided with chloroplast RNAs will be used to study the features of the RNA that are essential for recognition of the proper C target of editing. The maize extracts will also be fractionated in order to learn more about the molecules involved in converting C to U. These studies will take advantage of databases containing maize nuclear and chloroplast genome sequences, maize chloroplast protein sequence data, and maize mutant collections which were generated through projects supported by the NSF. Development of the in vitro editing extract will have a broad impact on the editing community. The project will provide training opportunities at several levels and include participation by underrepresented minorities.