Professor Phil Poole
Mechanisms of oxygen regulation in biological nitrogen fixation and their refactoring as synthetic biology tools to engineer nitrogen fixation
Nitrogen is a key nutrient for plant growth and the use of nitrogen fertilizers has resulted in significant boosts in crop productivity. However, these fertilizers also cause significant environmental damage and are unaffordable for much of the developing world. Many plant species instead acquire their nitrogen by forming a symbiotic relationship with nitrogen fixing Rhizobium bacteria. These enter into the plant’s roots where they transform into highly specialized quasi-organelles, providing the plant with nitrogen fixed from the atmosphere in exchange for nutrients and shelter. Oxygen is a key signal in the regulation of this transformation because it is toxic to the nitrogenase enzyme that performs nitrogen fixation. Two bacterial proteins, NifA and FnrN, are known to be critical for the regulation and activation of nitrogen fixation. The aim of my research is to study how these are regulated at the transcriptional and protein level and to determine the mechanisms by which this occurs. Next, we aim to use our understanding of these mechanisms to develop synthetic biology tools which can be used in efforts to introduce this symbiosis into other plants and bacteria. Achieving this could reduce the need for polluting nitrogen fertilizers and provide a sustainable way to boost crop yields.