Scientists construct energy production unit for a synthetic cell

September 18, 2019

Scientists at the University of Groningen have constructed synthetic vesicles in which ATP, the main energy carrier in living cells, is produced. The vesicles use the ATP to maintain their volume and their ionic strength homeostasis. This metabolic network will eventually be used in the creation of synthetic cells - but it can already be used to study ATP-dependent processes. The researchers described the synthetic system in an article that was published in Nature Communications on 18 September.

'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.

Equilibrium

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.'

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.

Transport protein

To create an out-of-equilibrium system, the ATP is used to maintain ionic strength inside the vesicle. A biological sensor measures ionic strength and if this becomes too high, it activates a transport protein that imports a substance called glycine betaine. This increases the cell volume and consequently reduces the ionic strength. 'The transport protein is powered by ATP, so we have both production and use of ATP inside the vesicle.'

The system was left to run for 16 hours in the longest experiment that the scientists have performed. 'This is quite long - some bacteria can divide after just 20 minutes,' says Poolman. 'The current system should suffice for a synthetic cell that divides once every few hours.' Eventually, different modules like this one will be combined to create a synthetic cell that will function autonomously by synthesizing its own proteins from a synthetic genome.

Artificial chromosome

The current system is based on biochemical components. However, Poolman's colleagues at Wageningen University & Research are busy collecting the genes needed for the production of enzymes used by the system and incorporating them into an artificial chromosome. Others are working on lipid and protein synthesis, for example, or cell division. The final synthetic cell should contain DNA for all these modules and operate them autonomously like a living cell, but in this case, engineered from the bottom-up and including new properties. However, this is many years away. 'In the meantime, we are already using our ATP-producing system to study ATP-dependent processes and advance the field of membrane transport,' says Poolman.
-end-
Reference: Tjeerd Pols, Hendrik R. Sikkema, Bauke F. Gaastra, Jacopo Frallicciardi, Wojciech M. Smigiel, Shubham Singh and Bert Poolman: A synthetic metabolic network for physicochemical homeostasis. Nature Communications 18 September 2019

University of Groningen

Related Living Cells Articles from Brightsurf:

Catalyzing a zero-carbon world by harvesting energy from living cells
Scientists from Nagoya University have achieved a breakthrough in converting energy-deficient metabolites to a biorenewable resource thanks to a versatile catalyst.

Igniting the synthetic transport of amino acids in living cells
Researchers from ICIQ's Ballester group and IRBBarcelona's PalacĂ­n group have published a paper in Chem showing how a synthetic carrier calix[4]pyrrole cavitand can transport amino acids across liposome and cell membranes bringing future therapies a step closer.

Nanocatalysts that remotely control chemical reactions inside living cells
POSTECH professor In Su Lee's research team develops a magnetic field-induced heating 'hollow nanoreactors'.

'Seeing' and 'manipulating' functions of living cells
Toyohashi University of Technology has given greater functionalities to atomic force microscopy (AFM).

Terahertz radiation can disrupt proteins in living cells
Researchers from the RIKEN Center for Advanced Photonics and collaborators have discovered that terahertz radiation, contradicting conventional belief, can disrupt proteins in living cells without killing the cells.

CSIC researchers use whole living cells as 'templates' to seek for bioactive molecules
A study performed by researchers at the Institute for Advanced Chemistry of Catalonia (IQAC-CSIC) from the Spanish National Research Council (CSIC) pioneers the use of whole living cells (human lung adenocarcinoma) in dynamic combinatorial chemistry systems.

A new tool to map the flow of info within living cells
UNC-Chapel Hill, UT Southwestern Medical Center researchers created a way to study the intricacies of intercellular signaling -- when, where, and how tiny parts of cells communicate -- to make cells move.

Genetically engineering electroactive materials in living cells
Merging synthetic biology and materials science, researchers genetically coaxed specific populations of neurons to manufacture electronic-tissue 'composites' within the cellular architecture of a living animal, a new proof-of-concept report reveals.

Physics of Living Systems: How cells muster and march out
Many of the cell types in our bodies are constantly on the move.

Bioprinting: Living cells in a 3D printer
A high-resolution bioprinting process has been developed at TU Wien (Vienna): Cells can now be embedded in a 3D matrix printed with micrometer precision -- at a printing speed of one meter per second, orders of magnitude faster than previously possible.

Read More: Living Cells News and Living Cells Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.