The radical impact of oxygen on prokaryotic evolution-enzyme inhibition first, uninhibited essential biosyntheses second, aerobic respiration third.

ABSTRACT: Molecular oxygen is a stable diradical. All O₂-dependent enzymes employ a radical mechanism. Generated by cyanobacteria, O₂ started accumulating on Earth 2.4 billion years ago. Its evolutionary impact is traditionally sought in respiration and energy yield. We mapped 365 O₂-dependent enzymatic reactions of prokaryotes to phylogenies for the corresponding 792 protein families. The main physiological adaptations imparted by O₂-dependent enzymes were not energy conservation, but novel organic substrate oxidations and O₂-dependent, hence O₂-tolerant, alternative pathways for O₂-inhibited reactions. Oxygen-dependent enzymes evolved in ancestrally anaerobic pathways for essential cofactor biosynthesis including NAD

SUBMITTER: Mrnjavac N 

PROVIDER: S-EPMC7616280 | biostudies-literature | 2024 Jul

REPOSITORIES: biostudies-literature