Chromosome-free bacterial cells are safe and programmable platforms for synthetic biology

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 12; pp. 6752 - 6761
• Main Authors: Fan, Catherine, Davison, Paul A., Habgood, Robert, Zeng, Hong, Decker, Christoph M., Salazar, Manuela Gesell, Lueangwattanapong, Khemmathin, Townley, Helen E., Yang, Aidong, Thompson, Ian P., Ye, Hua, Cui, Zhanfeng, Schmidt, Frank, Hunter, C. Neil, Huang, Wei E.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 24.03.2020
• Subjects: Antineoplastic Agents - pharmacology; Biodegradation; Biological Sciences; Biology; Catechol; Catechols - pharmacology; Cell Proliferation; Cellular Reprogramming; Chassis; Chromosomes; Chromosomes, Bacterial; Circuits; Cupriavidus necator - genetics; Cupriavidus necator - metabolism; Drug Delivery Systems; E coli; Endonuclease; Escherichia coli - genetics; Escherichia coli - metabolism; Gene Regulatory Networks; Genetic Engineering; Genomes; Glycolysis; Lung cancer; NADH; NADP; Neoplasms - drug therapy; Neoplasms - metabolism; Neoplasms - pathology; Nicotinamide adenine dinucleotide; Nuclease; Pseudomonas putida; Pseudomonas putida - genetics; Pseudomonas putida - metabolism; Salicylic acid; Soil bacteria; Synthetic biology; Synthetic Biology - methods; Tumor Cells, Cultured; minimal genome; synthetic biology; cancer; SimCells; bacterial therapy
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1918859117

A type of chromosome-free cell called SimCells (simple cells) has been generated from Escherichia coli, Pseudomonas putida, and Ralstonia eutropha. The removal of the native chromosomes of these bacteria was achieved by double-stranded breaks made by heterologous I-CeuI endonuclease and the degradation activity of endogenous nucleases. We have shown that the cellular machinery remained functional in these chromosome-free SimCells and was able to process various genetic circuits. This includes the glycolysis pathway (composed of 10 genes) and inducible genetic circuits. It was found that the glycolysis pathway significantly extended longevity of SimCells due to its ability to regenerate ATP and NADH/NADPH. The SimCells were able to continuously express synthetic genetic circuits for 10 d after chromosome removal. As a proof of principle, we demonstrated that SimCells can be used as a safe agent (as they cannot replicate) for bacterial therapy. SimCells were used to synthesize catechol (a potent anticancer drug) from salicylic acid to inhibit lung, brain, and soft-tissue cancer cells. SimCells represent a simplified synthetic biology chassis that can be programmed to manufacture and deliver products safely without interference from the host genome.