RNA METABOLISM IN TRYPANOSOMES

描述（由申请人提供）：在过去几年中，由于两项主要进展，对人类昏睡病和牛昏睡病的病原体布鲁氏锥虫的生物学研究取得了令人难以置信的增长：完成了布鲁氏锥虫基因组序列和我们实验室发现了RNA干扰（RNAi）。通过RNAi将基因组信息与下调基因功能连接起来，现在使用全局方法研究复杂的细胞机制是现实的。由于转录调控在布鲁氏体中的作用较小，因此对基因表达调控的重点主要集中在转录后调控机制上。因此，我们预计控制mRNA代谢的酶对这些寄生虫是必不可少的。本研究的重点是锥虫特有的RNA代谢（第4章生物合成和功能）或真核生物学中的新概念（反式剪接、聚腺苷化和RNAi途径的偶联）。

DESCRIPTION (provided by the applicant): In the last few years the study of the biology of Trypanosoma brucei, the agent of sleeping sickness in humans and nagana in cattle, has witnessed an incredible growth due to two major advances: the completion of the T. brucei genome sequence and the discovery by our laboratory of RNA interference (RNAi). By interfacing genome information with down-regulating gene function by RNAi, it is now realistic to investigate complex cellular mechanisms using global approaches. As transcription regulation plays a minor role in T. brucei, the emphasis on regulation of gene expression is primarily on post-transcriptional regulatory mechanisms. Thus, we anticipate that the enzymes governing mRNA metabolism are essential for these parasites. This proposal focuses on aspects of RNA metabolism that are either unique to trypanosomes (cap 4 biosynthesis and function) or are novel concepts in eukaryotic biology (coupling of trans-splicing and polyadenylation and the RNAi pathway). The long-term goal of this proposal remains the characterization of molecular mechanisms involved in RNA metabolism and their relevance to trypanosome biology. In the next funding period we plan to: 1. Characterize the specific RNA methyltransferases involved in cap 4 biosynthesis and investigate whether there is a mechanistic link between cap 4 formation and polyadenylation. 2. Further our understanding of the coupling of trans-splicing and polyadenylation by using a variety of approaches, including monitoring the association of processing factors along transcribed genes in living cells. 3. Further characterize the RNAi pathway in terms of its components and how the interaction of TbAGO1 with translating ribosomes is brought about.