Fig. 1.

Schematic overview of the workflow using ReSCuES and SCRaMbLE. On the left are a population of genetically identical cells containing ReSCuES and one or more synthetic chromosomes (Synthetic yeast). The composition of ReSCuES is illustrated in the rectangle. Pura3 represents the native URA3 promoter. ReSCuES could present in the yeast cells either in an episomal plasmid or integrated at a chromosome locus, rendering the cells as Ura⁺ Leu⁻. SynChr, synthetic chromosome. Green triangle represents the loxP site. Red diamond represents the symmetric loxP site (loxPsym). In the middle are the SCRaMbLEd yeast strains selected by ReSCuES. Recombination between the two loxP sites inverts the markers, producing Ura⁻ Leu⁺ clones. Simultaneously, rearrangements happen in SynChr, leading to inversion, deletion, and duplication as depictured. In this population, the genome of each cell might be different, which is represented by different colors. On the right are the desired yeast strains after applying certain selection pressures, which could be strains with favorable phenotypes, improvement on cellular chassis and other applications