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. Author manuscript; available in PMC: 2019 Mar 19.
Published in final edited form as: Biochemistry. 2018 Dec 21;58(11):1539–1551. doi: 10.1021/acs.biochem.7b01069

Figure 1. Recombination-mediated cassette exchange (RMCE) allows for high-efficiency genomic integration.

Figure 1.

A) We developed a cre-lox based RMCE that utilizes a combination of asymmetric (lox66 and lox71) and incompatible (lox and loxm2) loxP sites to allow for RMCE. We tracked the cell population with flow cytometry during RMCE. Left: Population of cells containing the mCherry landing pad engineered in the nth-ydgR locus prior to RMCE. Center: After transformation and RMCE of constitutively expressed sfGFP library, but prior to selection, both exchanged and unexchanged populations co-exist showing that an estimated two-thirds of the cells undergo RMCE. Right: Post-selection population shows 94.3% of the resultant population contains the cassette (as measured by constitutive sfGFP expression) and loss of the original landing pad mCherry expression. B) Expression of mCherry landing pads at six previously characterized locations spanning the E. coli genome31. Arrows indicate the landing pad orientation. C) Comparison of mCherry expression from the landing pad in both orientations at the nth-ydgr locus.