Site-recognition of RNA editing in chloroplasts

1. RNA编辑位点（1）在烟草（N. tabacum）叶绿体。因此，位点总数为38个，是迄今为止在高等植物叶绿体中发现的最多的。(2)来自烟草祖细胞（N sylvestris和N. tomentosiformis）进行了重新检查，并且在后一种物种中的这种编辑取决于培养条件。体外RNA编辑方法的改进利用荧光双脱氧核苷酸建立了一种快速、简便的体外RNA编辑方法. RNA编辑的顺式元件利用上述方法，测定了5种烟草ndh mRNA中19个位点的编辑活性。ndhB mRNA中的顺式元件被定义为从-6到-10的5个核苷酸（nt），而ndhF mRNA具有两个独立的顺式元件，从-1到-15的15个nt和从-36到-40.4的5个nt。转译因子利用荧光mRNA，尝试了一种检测转译因子进行编辑的方法.位点识别因子的分析分离得到了56 kD的psbE mRNA编辑反式因子，并测定了其部分氨基酸序列。数据库中未发现相似序列。

1. RNA editing sites(1) Two additional sites were identified in the ndhD mRNA from tobacco (N. tabacum) chloroplasts. The total number of sites is thus 38, the most so far found in higher plant chloroplasts.(2) ACG to AUG RNA editing in ndhD mRNAs from tobacco progenitors (N sylvestris and N. tomentosiformis) was reexamined, and this editing in the latter species occurred depending on culture conditions.2. Improvement of the in vitro RNA editing assayA rapid and simple in vitro assay was established using fluorescent dideoxynucleotides.3. Cis-elements for RNA editingUsing the above assay, editing activities of 19 sites in five tobacco ndh mRNA species were measured. A cis-element in the ndhB mRNA was defined to be 5 nucleotides (nt) from-6 to-10, whereas ndhF mRNAs have two separate cis-elements, 15 nt from-1 to-15 and 5 nt from-36 to-40.4. Trans-factorsUsing fuorescent mRNAs, a method to detect trans-factors for editing was tried.5. Analysis of site-recognition factorsThe 56 kD trans-factor for psbE mRNA editing was isolated, and its partial amino acid sequences were determined. No similar sequence was found in databases.