Early Archean origin of Photosystem II

Tanai Cardona*, Patricia Sánchez-Baracaldo, A. William Rutherford, Anthony W. Larkum

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

36 Citations (Scopus)
266 Downloads (Pure)


Photosystem II is a photochemical reaction center that catalyzes the light-driven oxidation of water to molecular oxygen. Water oxidation is the distinctive photochemical reaction that permitted the evolution of oxygenic photosynthesis and the eventual rise of eukaryotes. At what point during the history of life an ancestral photosystem evolved the capacity to oxidize water still remains unknown. Here, we study the evolution of the core reaction center proteins of Photosystem II using sequence and structural comparisons in combination with Bayesian relaxed molecular clocks. Our results indicate that a homodimeric photosystem with sufficient oxidizing power to split water had already appeared in the early Archean about a billion years before the most recent common ancestor of all described Cyanobacteria capable of oxygenic photosynthesis, and well before the diversification of some of the known groups of anoxygenic photosynthetic bacteria. Based on a structural and functional rationale, we hypothesize that this early Archean photosystem was capable of water oxidation to oxygen and had already evolved protection mechanisms against the formation of reactive oxygen species. This would place primordial forms of oxygenic photosynthesis at a very early stage in the evolutionary history of life.

Original languageEnglish
Pages (from-to)127-150
Number of pages24
Issue number2
Early online date17 Feb 2019
Publication statusPublished - 1 Mar 2019


  • Bacterial Proteins/analysis
  • Bayes Theorem
  • Cyanobacteria/genetics
  • Evolution, Molecular
  • Photosynthesis
  • Photosystem II Protein Complex/analysis
  • Phylogeny


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