CETCH Me If You Can: Bringing Inorganic Carbon into Life with Synthetic CO2 Fixation
Carbon dioxide (CO2) is a potent greenhouse gas that is a critical factor in global warming. At the same time atmospheric CO2 is a cheap and ubiquitous carbon source. Yet, synthetic chemistry lacks suitable catalysts to functionalize atmospheric CO2, emphasizing the need to understand and exploit the CO2 mechanisms offered by Nature.
In my talk we will (1) discuss the evolution and limitation of naturally existing CO2 fixing enzymes and pathways. I will (2) present strategies for the engineering and design of artificial CO2 fixation reactions and pathways (Peter et al. 2015), and (3) outline how these artificial pathways can be realized and further optimized to create synthetic CO2 fixation modules.
An example for such a synthetic CO2 fixation module is the CETCH cycle (Schwander et al. 2016). The CETCH cycle is an in vitro-reaction network of 17 enzymes that was established with enzymes originating from nine different organisms of all three domains of life and optimized in several rounds by enzyme engineering and metabolic proofreading. In its version 5.4, the CETCH cycle converts CO2 into organic molecules at a rate of 5 nanomoles of CO2 per minute per milligram of protein. This is slightly faster than the Calvin cycle under comparable conditions and notably at 20% less energy per CO2 fixed.