Genetic and biochemical analysis of selenoprotein biosynthesis in Archaea (B 11)

古细菌硒蛋白生物合成的遗传和生化分析 (B 11)

• 批准号: 34855524
• 金额: --
• 依托单位: Professur für Mikrobielle Diversität
• 依托单位国家: 德国
• 项目类别: Collaborative Research Centres
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/34855524?language=en
• 关键词: Genetic; biochemical; analysis; selenoprotein; biosynthesis

Proteins that contain selenocysteine, the 21st co-translationally inserted amino acid, arepresent in members of all three domains of life. The universal codon for selenocysteine is theopal (stop-) codon UGA on the mRNA. To mediate receding of the stop codon into a sensecodon, the presence of a secondary structure on the selenoprotein mRNA (the SECIS element)is required. While the mechanism of selenocysteine biosynthesis and its incorporation intonascent polypeptides is well understood in bacteria such as E. coli, surprisingly large gapsexist in the understanding of the archaeal and the eukaryal system. From what is known it isapparent that striking similarities exist in the process of selenoprotein biosynthesis of thelatter two domains. Thus, insights gained in one system are potentially applicable in the othersystem. Methanococcus maripaludis, a mesophilic, fast growing methanogenic archaeon is anexcellent model to study the mechanisms of selenoprotein biosynthesis in Archaea. It is theonly known selenoprotein-containing archaeon for which a facile system for genetic analysesis established. Furthermore, all of its selenoproteins were shown to be non-essential undercertain conditions. In the course of the proposed research the pathway of selenocysteinebiosynthesis and incorporation of M. maripaludis will be investigated by genetic andbiochemical approaches. Phenotypical analyses of mutants unable to synthesizeselenoproteins as well as biochemical analyses of gene products involved, will, beside theobvious value of the new insights, also lead to a better understanding of the less tractableeukaryal system.

含有硒半胱氨酸的蛋白质存在于生命的所有三个领域中。硒半胱氨酸是第21个共翻译插入的氨基酸。硒半胱氨酸的通用密码子是信使核糖核酸上的蛋白石(终止)密码子UGA。为了调节终止密码子向敏感密码子的退缩，需要在硒蛋白mRNA(SECIS元件)上存在二级结构。虽然硒半胱氨酸的生物合成及其结合的机制在大肠杆菌等细菌中得到了很好的理解，但令人惊讶的是，在对古生菌和真核生物系统的理解中存在着巨大的鸿沟。从已知的情况来看，后两个结构域的硒蛋白生物合成过程有惊人的相似之处。因此，在一个系统中获得的见解可能适用于另一个系统。甲烷球菌是一种中温、快速生长的产甲烷古生菌，是研究古细菌中硒蛋白生物合成机制的极佳模型。这是目前已知的唯一一种建立了简便的遗传分析系统的含硒蛋白考古体。此外，在某些条件下，它的所有硒蛋白都被证明是非必需的。在拟议的研究过程中，将通过遗传和生物化学方法研究maripaludis的硒半胱氨酸的生物合成和并入途径。对无法合成硒蛋白的突变体进行表型分析，以及对相关基因产品进行生化分析，除了新见解的明显价值外，还将有助于更好地理解较难处理的真核生物系统。