Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA.
Nat Microbiol. 2017 Apr 28;2:17067. doi: 10.1038/nmicrobiol.2017.67.
The tricarboxylic acid (TCA) cycle is central to energy production and biosynthetic precursor synthesis in aerobic organisms. There are few known variations of a complete TCA cycle, with the common notion being that the enzymes involved have already evolved towards optimal performance. Here, we present evidence that an alternative TCA cycle, in which acetate:succinate CoA-transferase (ASCT) replaces the enzymatic step typically performed by succinyl-CoA synthetase (SCS), has arisen in diverse bacterial groups, including microbial symbionts of animals such as humans and insects.
三羧酸 (TCA) 循环是需氧生物中能量产生和生物合成前体合成的核心。完整 TCA 循环的变体很少见，人们普遍认为涉及的酶已经进化到最佳性能。在这里，我们提供的证据表明，一种替代的 TCA 循环已经出现在各种细菌群体中，其中包括人类和昆虫等动物的微生物共生体，在这个循环中，乙酰辅酶 A:琥珀酸辅酶 A 转移酶 (ASCT) 取代了通常由琥珀酰辅酶 A 合成酶 (SCS) 完成的酶促步骤。
