Living cells learn to eat CO2

Newswise – Synthetic Biology Offers Opportunity to Build Biochemical Pathways to Capture and Transform Carbon Dioxide (CO)2). Researchers at the Max Planck Institute for Terrestrial Microbiology have developed a synthetic biochemical cycle that directly converts CO.2 In the central building block Acetyl-CoA. The researchers were able to introduce each module of the three cycles into the bacterium E. Colewhich represents a major step towards synthetic CO realization2 Defining pathways in the context of living cells.

Development of new ways of CO capture and conversion2 Key to addressing the climate emergency. Synthetic biology opens the way to create new carbon dioxide2– Fixation pathways that trap CO2 more efficiently than those developed by nature. However, realizing the ways of this new nature in different ways in vitro and alive Systems are still a fundamental challenge. Now, researchers in Tobias Erb's group have designed and built a new synthetic CO2-fixation path, the so-called THETA cycle. It contains several central metabolites as intermediates, and the central building block, acetyl-CoA, as its output. This feature allows it to be divided into modules and integrated into the central metabolism E. coli.

The entire THETA cycle includes 17 biocatalysts and is designed around the two fastest CO2– Fixation enzymes known to date: crotonyl-CoA carboxylase/reductase and phosphoenolpyruvate carboxylase. Researchers discovered these powerful biocatalysts in bacteria. Although each carboxylase can trap CO2 10 times faster than RubisCO, CO2– a chloroplast stabilizing enzyme, evolution itself did not assemble these capable enzymes into natural photosynthesis.

The THETA cycle converts two COs2 molecules in one acetyl-CoA in one cycle. Acetyl-CoA is a central metabolite in almost all cellular metabolism and serves as a building block for a wide range of vital biomolecules, including biofuels, biomaterials, and pharmaceuticals, making it of great interest in biotechnological applications. After building the cycle in test tubes, the researchers were able to confirm its functionality. Then the training began: through rational and machine-learning-driven optimization over several rounds of experiments, the team was able to improve the yield of acetyl-CoA by 100-fold. to check it alive Feasibility, incorporation into a living cell should be done step by step. To this end, the researchers divided the THETA cycle into three modules, each of which was successfully implemented in bacteria. E. coli. The functionality of these modules was verified by growth-coupled sampling and/or isotopic labeling.

“What is special about this cycle is that it contains several intermediates that act as central metabolites in the bacteria's metabolism. This overlap provides an opportunity to develop a modular approach to its implementation.” “We were able to demonstrate the functionality of three individual modules,” explains Shanshan Luo, lead author of the study. E. coli. However, we have not yet managed to close the entire cycle so that E. coli Can be completely increased with CO2“- he adds. Closing the THETA cycle is still a major challenge, as all 17 reactions must be synchronized with natural metabolism. E. coli, which naturally includes hundreds and thousands of reactions. However, demonstrating the entire cycle alive This is not the only goal, the researcher emphasizes. “Our cycle has the potential to become a versatile platform for the production of valuable compounds directly from CO2 by expanding its output molecule, acetyl-CoA,” says Shanshan Luo.

“Introducing parts of the TETA cycle into living cells is an important principle for synthetic biology,” adds Tobias Erb. “Such a modular implementation of this cycle E. coli paves the way for the realization of highly complex, orthogonal new natural CO2– Ways of fixation in cell factories. “We are learning to completely reprogram cellular metabolism to create a synthetic autotrophic operating system for the cell.”