A robust system for production of minicircle DNA vectors

Minicircle DNA vectors are superior to plasmids for long-term transgene expression but are not in widespread use because of a laborious production process. Kay et al. present an improved protocol for generating minicircles that makes them a viable alternative to plasmids for gene transfer studies. Minicircle DNA vectors allow sustained transgene expression in quiescent cells and tissues. To improve minicircle production, we genetically modified Escherichia coli to construct a producer strain that stably expresses a set of inducible minicircle-assembly enzymes, ΦC31 integrase and I-SceI homing endonuclease. This bacterial strain produces purified minicircles in a time frame and quantity similar to those of routine plasmid DNA preparation, making it feasible to use minicircles in place of plasmids in mammalian transgene expression studies.