Final Report Summary - TOHPN (Towards the optimization of hydrogen production by nitrogenase)
In the process of reducing N2 to NH3, the nitrogenase enzyme evolves H2. This observation prompted researches to investigate the applications of nitrogenase as catalyst for hydrogen production. However, major technical and conceptual barriers to re-engineer and optimize hydrogen production by nitrogenase have become apparent. The project Towards Optimization of Hydrogen Production by Nitrogenase (TOHPN) was conceived to help overcome these barriers. In TOHPN we have achieved the development of a genetic module for the screening of millions of hydrogen overproducing enzyme variants in a single experiment. An enzyme that is 10 fold better than its natural version in hydrogen production has been selected by using this tool. TOHPN also served to deepen our understanding of nitrogenase biosynthesis as a requisite to identify and rationally overcome the limiting steps of this pathway. Importantly, a H2 producing hybrid nitrogenase has been produced in vitro by replacing its active-site metal cluster (FeMo-co) by one of its biosynthetic intermediates. Finally, a number of biochemical events occurring during nitrogenase biosynthesis have been elucidated.