Molecular Clock Evidence For An Archean Diversification Of Heme-copper Oxygen Reductase Enzymes

Age estimates for the emergence of oxygenic photosynthesis derived from molecular clock analyses reach back to the Archean, substantially predating geochemical evidence of persistent, irreversible atmospheric oxygenation following the Great Oxidation Event (GOE).

Additional evidence for the Archean biological cycling of oxygen would provide valuable insight into environmental oxygen concentrations and dynamics during this time. Here, we present phylogenetic reconstructions and molecular clock analyses of heme‑copper oxygen reductases, enzymes that use oxygen as a terminal electron acceptor in many aerobic electron transport chains.

These analyses reveal that these enzymes likely emerged and diversified in the Mesoarchean, following the earlier emergence of oxygenic photosynthesis. These results are consistent with oxygen concentrations being sufficient for aerobic physiologies to persist in at least some environments prior to the GOE, adding a key component to our understanding of the history of planetary oxygenation independent of the geochemical record.

Molecular clock evidence for an Archean diversification of heme-copper oxygen reductase enzymes, Palaeogeography, Palaeoclimatology, Palaeoecology

Molecular Clock Evidence for an Archean Diversification of Heme-Copper Oxygen Reductase Enzymes, Astrobiology Habitable Environment Database

This dataset contains sequence files and tree files employed in the phylogenetic analysis and molecular dating of the heme-copper oxygen reductases. These ancient enzymes are key components of aerobic respiratory chains; they reduce molecular oxygen to water. Heme-copper oxygen reductase protein sequences were compiled, aligned, and used to construct phylogenetic trees. These phylogenetic trees were coupled with age constraints prior to molecular clock analysis. The resulting molecular clock analyses of these enzymes suggest that they emerged after oxygenic photosynthesis but prior to Earth’s Great Oxidation Event.

The protein sequence files can be viewed as text files, though they alternatively may be opened in a program like Jalview. Tree files may similarly be opened as text files or through a graphical viewing program like FigTree.

Astrobiology, evolution, genomics,