BPP and HinLVA plasmid constructs. A solved BPP plasmid (left) contains a flippable pLac promoter (blue arrow) and RBS-tetA(C) (green rectangle = RBS, purple arrow = tetA(C)). The pLac promoter is pancake 1 and RBS-tetA(C) is pancake 2. hixC sites (yellow rectangles) flank each flippable element. Inversion of pLac is detected by expression of the reverse (rev) upstream RBS-mRFP reporter. HinLVA is expressed from a second plasmid (right). AmpR = ampicillin resistance marker, ChlrR = chloramphenicol resistance marker, repA pSC101 and ColE1 = origins of replication, RBS = ribosome binding site, TT = double transcription terminator, white boxes = cloning sites.