Oxygen reductase origin followed the great oxidation event and terminated the Lomagundi excursion
Year: 2025
Type: article
Abstract: The history of Earth's atmospheric oxygen is a cornerstone of evolutionary biology. While unequivocal evidence for an increase in atmospheric O 2 marks the Great Oxidation Event (GOE) roughly 2.4 billion years ago, evidence underlying proposals for pre-GOE O 2 accumulation is debated. Here we have investigated the distribution of genes for oxygen reductases, the enzymes that consume O 2 in respiratory chains, across independently generated molecular timescales of prokaryotic evolution. The data indicate that cytochrome bd -oxidases, heme copper oxidases and alternative oxidases arose in the wake of the GOE ca. 2.4 billion years ago, after which the genes were subjected to abundant lateral gene transfer, a reflection of their utility in redox balance and membrane bioenergetics. The data lead us to propose a straightforward four-stage model for O 2 accumulation surrounding the GOE: (i) Negligible O 2 existed prior to the GOE. (ii) Cyanobacterial O 2 production started at the GOE, yet was capped at 2 % [ v /v] atmospheric O 2 , the threshold at which cyanobacterial nitrogenase is inhibited by O 2 . (iii) Production of 0.02 atm of O 2 (2 % [ v /v]) at the GOE buried roughly the entire atmospheric CO 2 inventory, causing sudden enrichment of 13 C in dissolved inorganic carbon (the Lomagundi 13 C anomaly), through RuBisCO isotope discrimination, without atmospheric O 2 exceeding 2 % [ v /v]. (iv) High atmospheric 12 C at the end of the Lomagundi excursion marks the origin of oxygen reductases, their rapid spread via function in respiratory CO 2 liberation, and the onset of equilibrium between photosynthetic O 2 production and respiratory O 2 consumption at 2 % atmospheric O 2 .
Language: English
Subfield: Paleontology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,680
OpenAlex ID: W4416867296