Convergent evolution of a modified, acetate-driven TCA cycle in bacteria
Waldan K Kwong1, Hao Zheng1, Nancy A Moran1
1Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA.
Nature Microbiology
|April 29, 2017
Summary
Scientists discovered an alternative tricarboxylic acid (TCA) cycle in bacteria. This variation uses acetate:succinate CoA-transferase (ASCT) instead of succinyl-CoA synthetase (SCS) for energy production.
Area of Science:
- Biochemistry
- Microbiology
- Metabolic pathways
Background:
- The tricarboxylic acid (TCA) cycle is crucial for cellular energy and biosynthesis in aerobic organisms.
- Enzymes in the canonical TCA cycle are generally considered highly optimized.
- Variations in this fundamental metabolic pathway are rare.
Purpose of the Study:
- To investigate potential alternative pathways for the TCA cycle.
- To identify novel enzymatic functions within central metabolism.
- To explore metabolic diversity in bacterial communities.
Main Methods:
- Comparative genomics analysis across diverse bacterial phyla.
- Bioinformatic identification of key metabolic enzymes.
- Phylogenetic analysis to trace the evolutionary history of the alternative pathway.
Main Results:
- Evidence for an alternative TCA cycle utilizing acetate:succinate CoA-transferase (ASCT) was found.
- This ASCT-based cycle replaces the function of succinyl-CoA synthetase (SCS).
- The alternative pathway is present in various bacterial groups, including animal symbionts.
Conclusions:
- The TCA cycle is more evolutionarily flexible than previously assumed.
- Alternative metabolic pathways can emerge and persist in diverse bacterial lineages.
- This discovery has implications for understanding microbial metabolism and symbiosis.
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