nucleation

LIT-1564: Chimeric origins and dynamic evolution of central carbon metabolism in eukaryotes

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Properties5
StatusActive — read in full 2026-10-27 (NOTE-1239) from the PubMed Central copy of the version of record (PMC11976288, open access); worth reading as a careful, enzyme-by-enzyme history of eukaryotic central carbon metabolism, showing Asgard contributions to cytosolic glycolysis and the pentose phosphate pathway, alphaproteobacterial ones mostly in the mitochondrial TCA cycle, other donors with none dominant, and extensive later replacement and retargeting (THEORY-1109). Read it knowing that it rests on 64 single-gene trees, several weakly supported and all in the supplement; that alphaproteobacterial contributions outnumber Asgard ones 17 to six; and that its support for syntrophy comes from a compartment split that any archaeal-host, bacterial-endosymbiont model predicts, so it does not discriminate syntrophy-first from complexity-first scenarios.
Version3
Tagsendosymbiosis, natural-sciences
Cited as “paper” byNOTE-1239 — Santana-Molina, Williams, Snel & Spang — Chimeric origins and dynamic evolution of central carbon metabolism in eukaryotes
Cited as “source” byTHEORY-1109 — Santana-Molina, Williams, Snel and Spang find that the last eukaryotic common ancestor's central carbon metabolism was chimeric: a few Asgard-archaeal enzymes in cytosolic glycolysis and the pentose phosphate pathway, four placed with Asgard archaea at bootstrap 39–97% and two ambiguously, most alphaproteobacterial ones in the mitochondrial TCA cycle and pyruvate conversion, and others from various bacteria with no third dominant donor, since remodelled by loss, horizontal replacement and retargeting so that compartment no longer follows origin; the authors take the cytosol–mitochondrion split as support for syntrophy, THEORY-1205 — Eukaryotes began in a syntrophic partnership: an archaeal host fermented sugars and passed reducing equivalents to an alphaproteobacterial endosymbiont that contributed a TCA cycle and an electron transport chain, which is why the last eukaryotic common ancestor's central carbon metabolism is archaeal in cytosolic glycolysis and the pentose phosphate pathway and alphaproteobacterial in the mitochondrial TCA cycle

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Santana-Molina, C., Williams, T. A., Snel, B. & Spang, A. (2025). Chimeric origins and dynamic evolution of central carbon metabolism in eukaryotes. Nature Ecology & Evolution 9(4): 613–627. doi:10.1038/s41559-025-02648-0.

Key takeaways

From the reading, NOTE-1239.

  • LECA had the whole pathway set, with redundant enzymes at several steps.
  • Asgard did contribute. ADPGK, APGM, enolase and RPIA nest with Asgard (bootstrap 39–97%); GPMI and pyruvate kinase do so ambiguously. Most are cytosolic, and most have since been replaced in many lineages.
  • The mitochondrion contributed more. Seventeen alphaproteobacterial enzymes, ten of them in the TCA cycle, mostly mitochondrial (THEORY-1109).
  • Other donors, none dominant. Planctomycetota–Verrucomicrobiota, Chlamydia, Fusobacteriota and others give single enzymes.
  • Origin no longer predicts compartment. Host-derived enzymes work in the mitochondrion and symbiont-derived ones in the cytosol.
  • Syntrophy is consistent, not shown. The cytosol–mitochondrion split is what every symbiogenetic model predicts.

Why this is here

A1 ranked it fifth, for metabolic integration during eukaryogenesis, and for discriminating syntrophy-first from complexity-first scenarios. With NOTE-159, the record’s only reading on eukaryogenesis.

The reading corrects both points. The paper bears on metabolic integration, but it does not discriminate syntrophy-first from complexity-first: it says nothing on timing, and its syntrophy support would hold under either. NOTE-1242 and NOTE-1237 are now readings on eukaryogenesis too (NOTE-1239).

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