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Inhibition of nitrogenase by oxygen in marine cyanobacteria controls the global nitrogen and oxygen cycles
1Institute of Marine and Coastal Science, Rutgers University, New Brunswick, New Jersey 08901, USA
2Faculty of Life Sciences, Bar Ilan University, Ramat Gan, 52900, Israel
3Department of Chemistry and Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544, USA
4Department of Geological Sciences, Rutgers University, USA
Abstract. Cyanobacterial N2-fixation supplies the vast majority of biologically accessible inorganic nitrogen to nutrient-poor aquatic ecosystems. The process, catalyzed by the heterodimeric protein complex, nitrogenase, is thought to predate that of oxygenic photosynthesis. Remarkably, while the enzyme plays such a critical role in Earth's biogeochemical cycles, the activity of nitrogenase in cyanobacteria is markedly inhibited in vivo at a post-translational level by the concentration of O2 in the contemporary atmosphere leading to metabolic and biogeochemical inefficiency in N2 fixation. We illustrate this crippling effect with data from Trichodesmium spp. an important contributor of "new nitrogen" to the world's subtropical and tropical oceans. The enzymatic inefficiency of nitrogenase imposes a major elemental taxation on diazotrophic cyanobacteria both in the costs of protein synthesis and for scarce trace elements, such as iron. This restriction has, in turn, led to a global limitation of fixed nitrogen in the contemporary oceans and provides a strong biological control on the upper bound of oxygen concentration in Earth's atmosphere.
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Citation: Berman-Frank, I., Chen, Y.-B., Gerchman, Y., Dismukes, G. C., and Falkowski, P. G.: Inhibition of nitrogenase by oxygen in marine cyanobacteria controls the global nitrogen and oxygen cycles, Biogeosciences Discuss., 2, 261-273, 2005. Bibtex EndNote Reference Manager
