ENZYMOLOGY OF ACETOTROPHIC METHANOGENESIS

乙酸酯转化为甲烷的途径研究 甲烷考古杆菌嗜热甲烷单胞菌鉴定出常见的酶 在生理和代谢上多样化的厌氧微生物中发现的 细菌域。其中三种酶在厌氧菌中几乎无处不在： (和)醋酸激酶、磷酸转乙酰酶和碳酸氢酶 (班级。醋酸激酶和磷酸转乙酰酶在蛋白合成中起关键作用 产生能量的途径和碳酸氢酶的广泛出现 暗示了这种酶同样重要的功能。它们的顺序是 嗜热菌产生的酶与细菌产生的酶有很高的同源性。 表示共同祖先和催化机制的结构域。尽管他们 在厌氧原核生物中广泛存在和重要，很少有机械性的 研究一直被报道，直到最近来自嗜热支原体的酶 在大肠杆菌中过量生产(这些酶中的第一种)打开 现代调查方法的方式。此应用程序建议 继续对这些酶的研究，以了解生化 性质，重点放在催化机理上。结果在意料之中 不仅有助于更深入地了解醋酸盐发酵 途径，但更重要的是到更广泛的厌氧微生物学领域 以及更远的地方。

Studies on the pathway for acetate conversion to methane by the methanoarchaeon Methanosarcina thermophila have identified enzymes commonly found in physiologically and metabolically diverse anaerobic microbes from the Bacteria domain. Three of these enzymes are virtually ubiquitous in anaerobes: acetate kinase, phosphotransacetylase, and carbonic anhydrases of the (and (classes. Acetate kinase and phosphotransacetylase play key roles in energy-yielding pathways, and the widespread occurrence of carbonic anhydrases suggests equally important functions for this enzyme. The sequences of these enzymes from M. thermophila have high identity to the enzymes from the Bacteria domain indicating common ancestors and mechanisms of catalysis. Despite their broad occurrence and importance in anaerobic procaryotes, very few mechanistic studies had been reported until the enzymes from M. thermophila were recently overproduced in Escherichia coli (the first for any of these enzymes) opening the way for modern methods of investigation. This application proposes to continue the investigation of these enzymes to understand the biochemical properties, focusing on the mechanisms of catalysis. The results are expected to contribute not only to a deeper understanding of the acetate fermentation pathway, but more importantly to the broader field of anaerobic microbiology and beyond.