Origin of oxygen on ancient Earth

July 27, 2022

Oxygen evolution was triggered by amino acid conversion

A collaborative research group of Nagoya University and the RIKEN CSRS has proposed a new hypothesis that oxygen evolution on ancient Earth originated from amino acid conversion in photosystem II (PSII), a photosynthetic oxygen-producing enzyme.

Photosynthetic oxygen evolution occurs when light energy decomposes water in the oxygen evolving system formed in photosystem II proteins of plants and cyanobacteria. The research group found that when they replaced the amino acids composing the oxygen evolving system (aspartic or glutamic acid) with other amino acids at a genetic level, those replaced amino acids were converted to the original ones after the protein synthesis, making oxygen generation recovered.

This finding suggests that the conversion of amino acids at the protein level might have formed the primitive oxygen evolving system in ancestral photosystem II, triggering photosynthetic oxygen evolution on ancient Earth.

Original article
Nature Communications doi:10.1038/s41467-022-31931-y
Y. Shimada, T. Suzuki, T. Matsubara, T. Kitajima-Ihara, R. Nagao, N. Dohmae, T. Noguchi,
"Post-translational amino acid conversion in photosystem II as a possible origin of photosynthetic oxygen evolution".
Naoshi Dohmae
Unit Leader
Biomolecular Characterization Unit