Synthetic ATP-independent Carbon Rearrangement Cycle For Theoretical Conversion of Glycerol to Mevalonate
In many biofuel and biochemical productions, Acetyl-CoA is an essential intermediate. In nature, routes that convert glycerol to Acetyl-CoA are not efficient in carbon conversion due to its release of CO2 molecule. To eliminate this carbon loss step, a synthetic glycerol utilization pathway has been constructed inspired by the non-oxidative glycolysis (NOG) pathway. The new pathway, which is termed glycerol condensation cycle (GCC), is different from NOG pathway due to its ATP-independent manner. By coupling glycerol oxidation—catalyzed by glycerol dehyrdrogenase (GldA)—and dihydroxyacetone (DHA) condensation—catalyzed by fructose-six-phosphate aldolase (FSA)—steps with NOG pathway, glycerol compound can be converted to Acetyl-CoA without carbon loss. In addition, compared to pathways in nature, GCC pathway requires minimum number of enzymes and presents as the most thermodynamically favorable route for Acetyl-CoA production from glycerol. Enzyme amounts were adjusted using experiments from ensemble modeling, FSA glycerol inhibition, and trial and error. For demonstrating its practicality, in vitro theoretical conversion of glycerol into a valuable compound mevalonate was conducted, and final carbon yield of 108.51% ï¿½ 25.20% was achieved using purified enzymes.