Heterodisulfide Reductase in Methanosarcina acetivorans

描述（由申请人提供）：甲烷生产对许多与人类有关的问题至关重要，包括全球变暖、废物处理和生物材料替代燃料的开发。地球上的大部分甲烷是由产甲烷的古细菌通过甲烷生成机制产生的。甲烷生成的一个重要步骤是甲烷生成后形成的CoB-CoM异硫化物的再生。负责CoB-CoM还原的酶复合物被称为杂二硫还原酶（Hdr）。活性甲烷藻的基因组包含编码可溶性HdrABC复合物和膜结合HdrDE复合物的orf。HdrABC和HdrDE是否具有专门的或完全冗余的功能，将通过创建报告基因融合、靶向基因缺失和嵌合Hdr复合物来测试。嵌合酶复合物的体外分析将用于鉴定特异性和选择性蛋白质的重要氨基酸残基：蛋白质相互作用。通过这些实验，甲烷生成和古细菌电子传递系统的机制将被阐明，从而深入了解对所有生命形式至关重要的能量产生和保存过程。

DESCRIPTION (provided by applicant): Methane production is critically important to a number of human-related problems including global warming, waste treatment, and the development of alternative fuels from biological materials. The bulk of methane on earth is produced by methanogenic archaea through the mechanism known as methanogenesis. An essential step in methanogenesis is regeneration of a CoB-CoM heterodi- sulfide formed upon methane production. The enzyme complex responsible for CoB-CoM reduction is known as heterodisulfide reductcase (Hdr). The genome of Methanosarcina acetivorans contains ORFs coding for a soluble HdrABC complex and a membrane-bound HdrDE complex. Whether HdrABC and HdrDE have specialized, or completely redundant functions, will be tested by creating reporter gene fusions, targeted gene deletions, and chimeric Hdr complexes. In vitro analysis of chimeric enzyme complexes will be used to identify amino acid residues important for specific and selective protein:protein interactions. Through these experiments, the mechanism of methanogenesis and the archaeal electron transport system will be elucidated, thereby gaining insight into the processes of energy generation and conservation that are essential to all forms of life.