Central metabolism of Archaea

古细菌形成生命的第三领域，具有许多遗传、结构和生化特征，被认为是祖先。古生菌的一个有趣的特征是其中心代谢途径的巨大多样性，其中许多从未在细菌或真核生物中被发现。近年来，我们在绿古菌中发现了两种新的自养CO2同化途径，在盐古菌中发现了一种不同寻常的醋酸同化途径。尽管这些研究和其他研究大大增加了我们对古菌生理学和生物化学的了解，但它们也发现了我们对古菌中枢代谢途径的认识上的一些空白。这些空白是：(i)在seula金属球藻中编码4-羟基丁酸-辅酶a连接酶的基因是未知的，应该被识别和表征；（ii）中温海洋I群古菌（' Thaumarchaeota '）自养固定二氧化碳的途径仍有待生物化学证明；（iii）一些火杆菌属植物的自养二氧化碳固定途径尚不清楚；（iv） marismortui Haloarcula乙酰辅酶a同化的甲基天冬氨酸循环需要进一步的实验支持以及关键酶的鉴定和表征。这些问题将解决实验使用不同的微生物，生物化学和遗传学的方法。

The Archaea form the third domain of life and possess many genetical, structural and biochemical features which are considered to be ancestral. An interesting feature of Archaea is a great diversity of their central metabolic pathways, many of which have never been identified in either Bacteria or Eukarya. In the last years, we have identified two novel autotrophic CO2 assimilation pathways in Crenarchaeota and an unusual acetate assimilation pathway in haloarchaea. Although these and other studies substantially increased our understanding of the archaeal physiology and biochemistry, they also identified several gaps in our knowledge of archaeal central metabolic pathways. Such gaps are: (i) the gene encoding 4-hydroxybutyrate-CoA ligase in Metallosphaera sedula is not known and should be identified and characterized; (ii) the pathway of autotrophic CO2 fixation in mesophilic marine group I Archaea (‘Thaumarchaeota’) remains to be proven biochemically; (iii) the pathway of autotrophic CO2 fixation in some Pyrobaculum species is unknown; (iv) the methylaspartate cycle of acetyl-CoA assimilation in Haloarcula marismortui requires further experimental support as well as identification and characterization of its key enzymes. These questions will be addressed experimentally using different microbiological, biochemical and genetical approaches.