Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Hamburg, Germany.
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China.
Biotechnol Bioeng. 2021 Mar;118(3):1366-1380. doi: 10.1002/bit.27658. Epub 2020 Dec 28.
Autotrophic or mixotrophic use of one-carbon (C1) compounds is gaining importance for sustainable bioproduction. In an effort to integrate the reductive glycine pathway (rGP) as a highly promising pathway for the assimilation of CO and formate, genes coding for glycine synthase system from Gottschalkia acidurici were successfully introduced into Clostridium pasteurianum, a non-model host microorganism with industrial interests. The mutant harboring glycine synthase exhibited assimilation of exogenous formate and reduced CO formation. Further metabolic data clearly showed large impacts of expression of glycine synthase on the product metabolism of C. pasteurianum. In particular, 2-oxobutyrate (2-OB) was observed for the first time as a metabolic intermediate of C. pasteurianum and its secretion was solely triggered by the expression of glycine synthase. The perturbation of C1 metabolism is discussed regarding its interactions with pathways of the central metabolism, acidogenesis, solventogenesis, and amino acid metabolism. The secretion of 2-OB is considered as a consequence of metabolic and redox instabilities due to the activity of glycine synthase and may represent a common metabolic response of Clostridia in enhanced use of C1 compounds.
自养或混合营养利用一碳（C1）化合物对于可持续生物生产变得越来越重要。为了将还原性甘氨酸途径（rGP）整合为同化 CO 和甲酸盐的极有前途的途径，成功地将来自 Gottschalkia acidurici 的甘氨酸合成酶系统的基因引入到具有工业利益的非模式宿主微生物 Clostridium pasteurianum 中。携带甘氨酸合成酶的突变体表现出对外源甲酸盐的同化和减少 CO 的形成。进一步的代谢数据清楚地表明，甘氨酸合成酶的表达对 C. pasteurianum 的产物代谢有很大影响。特别是，首次观察到 2-氧代丁酸（2-OB）作为 C. pasteurianum 的代谢中间体，并且仅通过甘氨酸合成酶的表达触发其分泌。讨论了 C1 代谢的扰动，因为它与中心代谢、产酸、溶剂形成和氨基酸代谢途径相互作用。2-OB 的分泌被认为是由于甘氨酸合成酶的活性导致的代谢和氧化还原不稳定性的结果，并且可能代表了 Clostridia 在增强 C1 化合物利用时的常见代谢反应。
