Discussion of the possibility of increasing the efficiency of photosynthesis using genetic and metabolic engineering methods.

Photosynthesis is the main process by which biomass of living matter is created from inorganic carbon. However, the efficiency of photosynthesis is low. The main reason for the low efficiency of photosynthesis is the properties of the enzyme that fixes carbon dioxide - ribulose-1,5-bisphosphate carboxylase/oxidase (RuBisCO). There are reasons to believe that it is impossible to improve the properties of RuBisCO. It is apparently possible to significantly increase the efficiency of photosynthesis only by replacing RuBisCO with another enzyme. Among the known enzymes capable of fixing CO2, there is only one enzyme whose kinetic properties exceed those of RuBisCO, this is phosphoenolpyruvate carboxylase (PEPC). However, plants using PEPC are not able to use it as the only carbon dioxide fixer and to do without RubisCO. The cause for this is the absence of a metabolic cycle reproducing the substrate PEPC from its product. Advances in techniques of genetic, metabolic, protein and enzymes engineering make it possible to accomplish tasks that were previously considered impossible. Arren Bar-Even et al. suggested a hypothetical MOG cycle (from malonyl-CoA-oxaloacetate-glyoxylate) for the reproduction of PEPC substrate from its product, which should make it possible to abandon the use of RuBisCO and replace it with PEPC, which is expected to increase the efficiency of plant photosynthesis. This review analyzes the properties of the MOG cycle, and also suggests options for its modifications by adding other metabolic pathways. The possibility of further increasing the efficiency of photosynthesis through CO2 fixation at night is also being discussed.