ENZYMOLOGY OF ACETOTROPHIC METHANOGENESIS

乙酸盐转化为甲烷的途径研究 甲烷古菌嗜热甲烷八叠球菌已经鉴定出常见的酶， 在生理和代谢多样的厌氧微生物中发现， 细菌领域。这些酶中有三种几乎普遍存在于厌氧菌中： 乙酸激酶、磷酸转乙酰酶和碳酸酐酶（和 （类。乙酸激酶和磷酸转乙酰酶在 能量产生途径，以及碳酸酐酶的广泛存在 表明了这种酶同样重要的功能。这些序列 M.嗜热菌与细菌的酶具有高度的同一性 域指示共同的祖先和催化机制。尽管他们 在厌氧原核生物中广泛发生和重要性，很少有机制 研究已经被报道，直到M.嗜热菌最近 在大肠杆菌中过度产生（这些酶中的任何一种的第一种） 现代调查方法的发展。本申请建议 继续研究这些酶，以了解生物化学 性质，侧重于催化机制。结果预计 不仅有助于更深入地了解醋酸发酵 途径，但更重要的是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.