Cellular Machineries Devoted to Rubisco–the Most Abundant Enzyme

Abstract

Photosynthesis is a fundamental process in biology as it converts solar energy into chemical energy and thus, directly or indirectly, fuels all life on earth. The chemical energy is used to fix atmospheric CO2 and produce reduced carbon compounds in the Calvin-Benson-Bassham cycle. The key enzyme for this process in all photosynthetic organisms is ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), which is responsible for the conversion of an estimated amount of ~1011 tons of CO2 per annum into organic material. Rubisco is the most abundant enzyme in nature, owing in part to its low catalytic turnover rate and limited specificity for CO2 versus O2. Recent forecasts suggest that global food production will need to rise more than 25% by 2050 to meet the ever increasing demand. Engineering a catalytically more efficient Rubisco enzyme and/or compartmentalizing Rubisco in higher plants could contribute to reaching that goal. However, the complex nature of Rubisco's folding and assembly pathway has made these efforts exceedingly challenging. In my talk I will review recent progress in understanding the complex chaperone machineries that are necessary for the efficient biogenesis of Rubisco, and the mechanism by which the AAA+ chaperone Rubisco activase repairs Rubisco when it gets inhibited during photosynthesis by non-substrate sugar phosphates.