A bipartite promoter. Our bipartite promoter is made of fragments of the yeast VPH1 and minimal CYC1 promoters. The former provides the anchor point for RNA polymerases, the latter contains the TSS (see the Additional file 1 for their sequences). One or two operators are placed between the TATA box and the TSS such that repressor proteins can bind the DNA and inhibit transcription. TetOp, lacOp, and lexOp sequences are taken, in the order, from [32–34]. We modified the lacOp sequence with a T at the end–when it was placed close to the TATA box (position p1) or it was the only promoter operator–and with an A at the beginning, when it was inserted close to the TSS (position p2). In this way, the three operators used in this work had the same length (19 nucleotides).