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


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.

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Figure 1: An acetate-driven TCA cycle in diverse bacteria.


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This work was supported by the Canadian Natural Sciences and Engineering Research Council through Postgraduate Scholarship award PGSD-3-420434-2012 (to W.K.K.), the US National Science Foundation Dimensions of Biodiversity awards 1046153 and 1415604 and the US National Institutes of Health award 1R01GM108477-01 (to N.A.M.).

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Conceptualization, formal analysis, visualization and writing of the original draft were carried out by W.K.K. Methodology and investigation were performed by W.K.K. and H.Z. Writing, reviewing and editing of the manuscript were carried out by W.K.K., H.Z. and N.A.M. Resources and supervision were provided by N.A.M.

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Correspondence to Waldan K. Kwong.

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The authors declare no competing financial interests.

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Supplementary Figures 1–3, Supplementary Tables 1 and 2. (PDF 263 kb)

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Kwong, W., Zheng, H. & Moran, N. Convergent evolution of a modified, acetate-driven TCA cycle in bacteria. Nat Microbiol 2, 17067 (2017).

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