Convergent evolution of a modified, acetate-driven TCA cycle in bacteria

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.

MeSH terms

  • Acetates / metabolism*
  • Acetobacter / metabolism
  • Animals
  • Bacteria / metabolism*
  • Citric Acid Cycle / genetics*
  • Coenzyme A-Transferases / metabolism*
  • Energy Metabolism
  • Evolution, Molecular*
  • Gastrointestinal Microbiome / physiology
  • Humans
  • Succinate-CoA Ligases / metabolism


  • Acetates
  • Coenzyme A-Transferases
  • acetate-succinate CoA-transferase
  • Succinate-CoA Ligases