'Our aim is the bottom-up construction of a synthetic cell that can sustain itself and that can grow and divide,' explains University of Groningen Professor of Biochemistry Bert Poolman. He is part of a Dutch consortium that obtained a Gravitation grant in 2017 from the Netherlands Organisation for Scientific Research to realize this ambition. Different groups of scientists are producing different modules for the cell and Poolman's group was tasked with energy production.
All living cells produce ATP as an energy carrier but achieving sustainable production of ATP in a test tube is not a small task. 'In known synthetic systems, all components for the reaction were included inside a vesicle. However, after about half an hour, the reaction reached equilibrium and ATP production declined,' Poolman explains. 'We wanted our system to stay away from equilibrium, just like in living systems.'
PhD - Students - Group - Years - System
It took three Ph.D. students in his group nearly four years to construct such a system. A lipid vesicle was fitted out with a transport protein that could import the substrate arginine and export the product ornithine. Inside the vesicle, enzymes were present that broke down the arginine into ornithine. The free energy that this reaction provided was used to link phosphate to ADP, forming ATP. Ammonium and carbon dioxide were produced as waste products that diffused through the membrane. 'The export of ornithine produced inside the vesicle drives the import of arginine, which keeps the system running for as long as the vesicles are provided with arginine,' explains Poolman.
To create an...
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