Origin of photosynthetic water oxidation at the dawn of life [article]

Thomas Oliver, Patricia Sánchez-Baracaldo, Anthony W. Larkum, A. William Rutherford, Tanai Cardona
2020 biorxiv/medrxiv   pre-print
AbstractOxygenic photosynthesis starts with the oxidation of water to O2. Cyanobacteria are the only known prokaryotes capable of oxygenic photosynthesis and therefore, it is assumed that water oxidation is a late innovation relative to the origin of life. However, when exactly oxygenic photosynthesis originated remains lively debated. Here we show that the origin of photosystem II, the water-splitting enzyme, occurred at an early stage during the evolution of life and long before the origin of
more » ... efore the origin of Cyanobacteria. We use relaxed molecular clocks, ancestral sequence reconstruction, and comparative structural biology to demonstrate that photosystem II exhibits patterns of evolution through geological time that are indistinguishable from those of ATP synthase, RNA polymerase, or the ribosome—some of the oldest known enzymes. Our work suggests that water oxidation originated during the establishment of bioenergetics reaching farther into the past than can be documented based on species trees alone.
doi:10.1101/2020.02.28.969766 fatcat:a5h2dpg5n5grdlrlzemp6bhugu