Research School of Biology, The Australian National University
The photosynthetic enzyme linking the inorganic and organic phases of the biosphere is Ribulose-1,5-bisphosphate [RuBP] carboxylase/oxygenase (Rubisco). Encumbering the CO2-fixing performance of all Rubisco isoforms is a complicated catalytic chemistry that slows turnover rate, allows for competitive inhibition by oxygen and can produce misfire products that can self-inhibit activity. Significant effort has been invested into better understanding the structure-function details of Rubisco as improving its performance is recognised as a viable means to enhance the photosynthetic efficiency and yield potential of crops. Simulations of natural kinetic diversity has identified Rubisco variants of potential benefit to C3-photosynthesis with sequence analyses highlighting amino acids under evolutionary selection pressure with theoretical predictions used to speculate those that might influence catalysis. The challenge is taking the next step to translate simulation into reality. In this talk I will provide examples of new technologies and their limitations to bioengineering different Rubisco phylogenies in leaf chloroplasts. Shown will be a summary of successful use of directed evolution to improve Rubisco performance that translated to supporting higher rates of leaf photosynthesis and improved plant growth.