title: How did life survive Earth's great oxygenation?
abstract: Life on Earth originated and evolved in anoxic environments. Around 2.4 billion-years-ago, ancestors of Cyanobacteria invented oxygenic photosynthesis, producing substantial amounts of O2 as a byproduct of phototrophic water oxidation. The sudden appearance of O2 would have led to significant oxidative stress due to incompatibilities with core cellular biochemical processes. Here we examine this problem through the lens of Cyanobacteria-the first taxa to observe significant fluxes of intracellular dioxygen. These early oxygenic organisms likely adapted to the oxidative stress by co-opting preexisting systems (exaptation) with fortuitous antioxidant properties. Over time more advanced antioxidant systems evolved, allowing Cyanobacteria to adapt to an aerobic lifestyle and become the most important environmental engineers in Earth history.
authors.affiliation: Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States. Electronic address: wfischer@caltech.edu.
authors.forename: Woodward W
authors.initials: WW
authors.lastname: Fischer
authors.affiliation: Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States.
authors.forename: James
authors.initials: J
authors.lastname: Hemp
authors.affiliation: Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States; Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, United States. Electronic address: jsv@chem.ucla.edu.
authors.forename: Joan Selverstone
authors.initials: JS
authors.lastname: Valentine
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D000458:Cyanobacteria / Q000378:metabolism; D018534:Earth, Planet; D005844:Geology; D010100:Oxygen / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D010100:Oxygen