Initiation of Translation in halophilic Archaea.

翻译是遗传信息表达中非常重要的一步。已知的翻译启动机制有四种，即细菌和古菌使用的基于Shine-Dalgarno基序的机制，真核生物的扫描机制和依赖IRES的机制，以及无引导性转录本的启动机制。我们发现，大多数嗜盐古菌的转录本是无前导的，只有极少数有前导转录本包含SD序列。在无SD引导的转录本上的启动与所有已知的途径不同，因此至少在盐生古生菌中存在一种新的机制。翻译启动的分子表征是本研究的重点，包括启动元件的诱变、三种启动机制的不同使用以及启动因子的条件性缺失。翻译的调节通常发生在启动过程中，这是限速的。盐生古生菌的翻译调控需要5‘-和3’-UTRs。将分析盐生古生菌的翻译调控机制，包括调控的全球分析、RNA元件的特征以及调控因子的鉴定。

Translation is a very important step in the expression of genetic information. Four mechanisms for translation initiation are known, i.e. the Shine-Dalgarno motif-based mechanism used by bacteria and archaea, the scanning mechanism and the IRES-depending mechanism of eukaryotes, and initiation at leaderless transcripts. We dis-covered that the majority of haloarchaeal transcripts are leaderless and that only very few leadered transcripts contain a SD sequence. Initation on SD-less leadered transcript is distinct from all previously known path-ways, therefore a novel mechanism exists at least in haloarchaea. Molecular characterization of translation initiation in haloarchaea is a major focus of the proposed research, including mutagenesis of initiation elements, characterization of differential usage of the three initiation mechanisms, and conditional depletion of initiation factors. Regulation of translation typically occurs during initiation, which is rate-limiting. Translational regulation in haloarchaea requires both 5’- and 3’-UTRs. The mechanism of translational regulation in haloarchaea will be analyzed, including global analysis of regulation, characterization of RNA elements, and identification of regulatory factors.