Synthetic cell feeds, grows and divides

A synthetic cell created entirely from non-living chemical components can grow, replicate its genetic material and divide, completing the typical life cycle of a cell in the laboratory.

The cell-like system, known as 'SpudCell', was developed by researchers at the University of Minnesota. It is capable of carrying out a complete cycle of gene expression, DNA replication and cell division within a solution containing nucleotides, proteins and other essential cellular components. The work has been presented in a preprint available on bioRxiv, which means it has not yet undergone peer review.

'It is not as robust, as fast, or as good at most of its functions as a natural cell, but it is proof of principle that molecules can reconstitute behaviours that up until now we only associated with natural living cells', Dr Kate Adamala, an associate professor who led the research, told the Guardian. 'If we want to be able to engineer biology, we really have to understand exactly the blueprint, every component of it, so we know what we're changing.'

Although SpudCell can complete the full life cycle of a cell in the laboratory, it is not yet fully self-sustaining in the way that natural biological cells are. However, SpudCell provides a laboratory platform for investigating the minimum components required for cellular life and for engineering increasingly complex synthetic cells.

For decades, scientists have been studying how to build a cell from scratch that reflects the essential functions of life. Yet the complexity of even the simplest life forms makes it difficult to determine the minimum genetic requirements for cellular life. The widely used model organism E. coli has around 4000 genes, for example, while the human genome is estimated to carry around 20,000 genes.

Rather than aiming to delete genes from a complete genome, SpudCell was built from the ground upusing 36 essential bacterial genes distributed across seven plasmids. This enabled the team to separate SpudCell's various functions across the plasmids, while also providing a template to which more complex behaviours could be added. However, the team intends to eventually combine these plasmids into a single genome.

One long-term goal of synthetic biology is to design cells with specialised functions, including the production of medicines and industrial chemicals with greater efficiency and cost-effectiveness.

'We want to be able to make all petrochemicals with living biology, so we can basically move away from oil for all the climate and societal benefits,' Dr Adamala told the New Scientist. She added that synthetic cells could be designed to tolerate the toxicity of essential chemicals, which would ordinarily kill living cells.

Since SpudCell cannot yet synthesise new ribosomes, its protein-making machinery must still be supplied externally. Additionally, while SpudCell can technically divide in a very basic way, the researchers observed around ten generations before the system began to lose function. This likely occurs due to the ribosomes becoming defective, but could also be linked to SpudCell's pathway for DNA replication, which is unable to ensure faithful separation of the plasmids.

Dr Adamala and colleagues have founded the non-profit organisation Biotic to continue developing SpudCell and, in the words of co-founder Dr Drew Endy, associate professor of bioengineering from Stanford University, California, to build 'an operating system for life'.