コバミド生合成の進化の時間軸を解明（Study Reveals Evolutionary Timeline of Cobamide Biosynthesis）

2026-07-11 中国科学院（CAS）

＜関連情報＞

• https://english.cas.cn/newsroom/research-news/202607/t20260712_1177111.shtml
• https://www.pnas.org/doi/10.1073/pnas.2610446123

コバミド生合成の進化に関する分子レベルの時間スケール A molecular timescale for evolution of cobamide biosynthesis

Jichen Wang, Chao Ai, James M. Tiedje, and Yuan Ge
Proceedings of the National Academy of Sciences  Published:July 1, 2026
DOI:https://doi.org/10.1073/pnas.2610446123

Abstract

Cobamides are essential nutrients for most organisms but are only biosynthesized by a limited number of taxa through aerobic and anaerobic pathways. Although the origin of these widespread shared cofactors changed ecosystems and the metabolisms of living organisms, little evolutionary information is available about the biosynthetic genes and the producers. Here, we established a timeframe for the emergence of cobamide biosynthesis genes and producers, using a series of Bayesian molecular clock analyses combined with phylogenetic reconciliation. We revealed the partial producers of tetrapyrrole precursor and corrin ring were earlier than the oldest cobamide producer, suggesting the possibility that cobamide-like compounds may have existed before the emergence of their de novo producers. We also found that the anaerobic de novo producers and corrin ring producers emerged first (Pelobacter, around 2458 Mya), and that the Great Oxidation Event postdated emergence of aerobic producers (Kribbella, around 1784 Mya). These findings reveal the chronology of cobamide biosynthesis, which greatly changed global ecological frameworks and resulted in the current biosphere, and can guide the exploration of cross-feeding and the origin of diverse organisms on the planet.