Institute for Molecular Evolution, Heinrich-Heine-University, 40225, Düsseldorf, Germany.
Commun Biol. 2021 Mar 26;4(1):413. doi: 10.1038/s42003-021-01918-4.
Bacteria are the most abundant cells on Earth. They are generally regarded as ancient, but due to striking diversity in their metabolic capacities and widespread lateral gene transfer, the physiology of the first bacteria is unknown. From 1089 reference genomes of bacterial anaerobes, we identified 146 protein families that trace to the last bacterial common ancestor, LBCA, and form the conserved predicted core of its metabolic network, which requires only nine genes to encompass all universal metabolites. Our results indicate that LBCA performed gluconeogenesis towards cell wall synthesis, and had numerous RNA modifications and multifunctional enzymes that permitted life with low gene content. In accordance with recent findings for LUCA and LACA, analyses of thousands of individual gene trees indicate that LBCA was rod-shaped and the first lineage to diverge from the ancestral bacterial stem was most similar to modern Clostridia, followed by other autotrophs that harbor the acetyl-CoA pathway.
细菌是地球上数量最多的细胞。它们通常被认为是古老的，但由于其代谢能力的惊人多样性和广泛的横向基因转移，第一个细菌的生理学仍然未知。从 1089 个细菌厌氧菌的参考基因组中，我们鉴定出了 146 个蛋白质家族，这些家族可以追溯到最后一个细菌共同祖先 LBCA，并形成了其代谢网络的保守预测核心，该核心仅需要 9 个基因就能包含所有普遍的代谢物。我们的研究结果表明，LBCA 朝着细胞壁合成进行了糖异生作用，并且具有许多 RNA 修饰和多功能酶，这些酶使得低基因含量的生命成为可能。与最近对 LUCA 和 LACA 的发现一致，对数千个单独基因树的分析表明，LBCA 是杆状的，最早从祖先细菌主干分化出来的谱系与现代梭菌最为相似，其次是其他含有乙酰辅酶 A 途径的自养生物。
