SPLICING OF GROUP II AND GROUP III INTRONS

该项目是对结构、功能和拼接的研究 II组和III组内含子和双子内含子的机制 细小裸藻质体基因组的（“内含子内含子”） 和相关的原生生物。 这些生物体是已知最丰富的来源 II 组内含子，并且具有唯一已知的 II 组和 III 组 双子管。 具体目标包括：（1）小说的表征 相关物种中的 II 组和 III 组内含子和双含子 眼虫作为一种手段来探索（i）可能的“创始人”事件 内含子入侵，（ii）II组和III组内含子是否共享一个 RNA剪接所需的常见保守结构基序； (2) 安 III 组内含子拼接作用的研究，以及 (3) II组和III组内核的顺式作用域分析 转基因 I. gracilis 叶绿体体内剪接所需的。 这一目标将扩大到包括内含子的定点诱变 如果质体转化方面有足够的技术进步，则成熟 实现了。 这项工作旨在理解基本问题 关于内含子和孪生子的起源和进化。 一个正在工作的 假设是 II 组和 III 组内含子以及核 前 mRNA 剪接体内切子，可能都具有共同的进化特征 祖先。 因此，对最小的个体中异常变异的研究 II 组和 III 组内含子应与理解相关 RNA 结构是所有剪接反应的核心。

This project is a study of the structure, function, and splicing mechanisms of the group II and group III introns and twintrons ("introns-within-introns") of the plastid genomes of Euglena gracilis and related protists. These organisms are the richest known source of group II introns, and have the only known group II and group III twintrons. The specific aims include: (1) Characterization of novel group II and group III introns and twintrons in species related to Euglena gracilis as a means to explore (i) possible "founder" events of intron invasion, (ii) whether group II and group III intorns shared a common conserved structural motifs required for RNA splicing; (2) An investigation of the role of the group III intron spicing, and (3) Analysis of cis-acting domains of group II and group III intorns required for in vivo splicing in transgenic I. gracilis chloroplasts. This aim will be expanded to include site-directed mutagenesis of intron maturases if sufficient technical progress in plastid transformation is achieved. This work is addressed at understanding fundamental questions about the origins and evolution of introns and twintrons. A working hypothesis is that group II and group III introns, as well as nuclear pre-mRNA spliceosomal intorns, may have all shared a common evolutionary ancestor. Therefore, studies on unusual variants among the smallest group II and group III introns should be relevant to understanding the RNA structures at the heart of all splicing reactions.