BioBrick burden

Engineered DNA will slow the growth of a cell if it drains limiting resources such ribosomes or polymerases used for expressing genes or otherwise interferes with cellular homeostasis. Populations of engineered cells can rapidly become dominated by "escape mutants" that evolve to alleviate this burden by inactivating the intended function. Synthetic biologists working with bacteria rely on genetic parts and devices encoded on plasmids. Yet, the burden and stability of different engineered DNA sequences is rarely characterized. We systematically measured how BioBrick genetic parts created by teams participating in the iGEM (International Genetically Engineered Machine) competition affected the growth rate of Escherichia coli. We sequenced these BioBrick plasmids to validate their identities and detect signs of unintended evolution. We also created simulation models to investigate when escape mutants would be likely to arise in the laboratory and during scale-up of industrial processes. Overall, our results will help researchers understand and guard against evolutionary failure.