Fig. 2

The direct RBS engineering strategy on the violaceins biosynthetic gene cluster in this work. a The gene elements of violaceins biosynthetic operon vioABCDE within the plasmid of pETduet-1. The RBS (AAGGAG) of vioA is 8 bp upstream of its initial codon “ATG”. The RBS (GGGAAA) of vioB is 3 bp upstream of its initial codon “ATG”. The RBS (GAGAGG) of vioC is 6 bp upstream of its initial codon “ATG” and simultaneously located within the ORF of vioB. The RBS (AGGGAG) of vioD, 9 bp upstream of its initial codon “ATG” locates within the ORF of vioC while the initial codon “ATG” of vioD forms overlapping gene with the stop codon “TGA” of vioC. The RBS (AGGAGG) of vioE is 4 bp upstream of its initial codon “ATG”. b The total working process of the four-rounds of RBS mutagenesis on the violaceins biosynthetic gene cluster in this study. Blue boxes and Blue points represent the RBS elements within the vioABCDE operon. Red boxes represent the elements including T7 promoter, T7 terminator and the ORF of the five genes