Join us for our next Science Forum Lecture Series with Assistant Professor of Chemistry Dr. Cedric Owens for his talk titled Nobody can do it alone. Good friends are there to help nitrogenase when the going gets tough.

Light refreshments will be served.

Abstract:

The conversion of atmospheric nitrogen gas into ammonia is called nitrogen fixation. This process is important ecologically since ammonia is the main entry point of nitrogen into the biosphere. Ammonia is a growth-limiting nutrient for plants, including for commercial crops. There are two pathways to fix nitrogen: The Haber-Bosch process produces ammonia industrially and is responsible for fertilizer production. Although the Haber-Bosch process is critical for modern agriculture, it is also problematic since it is highly polluting. The second pathway is through biological nitrogen fixation by the enzyme nitrogenase. This process occurs naturally in a relatively small number of bacteria called diazotrophs. Nitrogen fixation by nitrogenase is non-polluting. Long-term research efforts focus on harnessing nitrogenase’s chemistry to synthesize fertilizer in more environmentally friendly ways or by substituting industrial fertilizers with ammonia made by plant-associating diazotrophs.

Dr. Owen's research focuses on determining how diazotrophs maintain nitrogenase activity under challenging conditions. Both the extracellular environment and cytosol are full of compounds that are inhibitory to nitrogenase. To prevent nitrogenase inhibition, diazotrophs have evolved protective mechanisms to precisely regulate when nitrogenase is expressed and to keep nitrogenase running despite the presence of inhibitors. This talk will discuss how nitrogenase expression is regulated by the iron-sulfur cluster-containing transcriptional regulator NifA in response to redox levels and how nitrogenase is protected from inhibition by carbon monoxide by the accessory protein CowN.