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The Effect of Oxygen on Biochemical Networks and the Evolution of Complex Life
Jason Raymond1 and
Daniel Segrè1,2
The evolution of oxygenic photosynthesis and ensuing oxygenationof Earth's atmosphere represent a major transition in the historyof life. Although many organisms retreated to anoxic environments,others evolved to use oxygen as a high–potential redoxcouple while concomitantly mitigating its toxicity. To understandthe changes in biochemistry and enzymology that accompaniedadaptation to O2, we integrated network analysis with informationon enzyme evolution to infer how oxygen availability changedthe architecture of metabolic networks. Our analysis revealedthe existence of four discrete groups of networks of increasingcomplexity, with transitions between groups being contingenton the presence of key metabolites, including molecular oxygen,which was required for transition into the largest networks.
1 Microbial Systems Division, Biosciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. 2 Bioinformatics Program, Department of Biology and Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
