Central metabolism of Archaea

古生物构成了生命的第三个领域，并具有许多被认为是祖先的遗传、结构和生化特征。古生菌的一个有趣的特征是它们的中心代谢途径非常多样化，其中许多从未在细菌或真核生物中被发现。在过去的几年里，我们发现了两条新的自养CO2同化途径，一条是在盐生古生菌中不同寻常的醋酸盐同化途径。虽然这些研究和其他研究大大增加了我们对古生菌生理和生物化学的了解，但它们也发现了我们对古生菌中枢代谢途径知识的几个空白。这些差距是：(I)编码4-羟基丁酸-CoA连接酶的基因尚不清楚，应被鉴定和鉴定；(Ii)中温海洋I群古生菌(‘Thaumararota’)自养固定二氧化碳的途径仍有待生化证明；(Iii)一些火杆菌物种的自养固定二氧化碳的途径尚不清楚；(Iv)海洋嗜盐藻乙酰-CoA同化的甲基天冬氨酸循环需要进一步的实验支持以及对其关键酶的鉴定和表征。这些问题将通过不同的微生物学、生物化学和遗传学方法在实验中解决。

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.