Fig 1. Hybrid promoter design and regulation.
(A) Structure schematics of the native HO promoter and the synthetic TX, TXC and TXC2 promoters. Regulatory elements are shown as colored rectangular boxes. The HO promoter is regulated by two upstream regulatory sites (URS1 and URS2) and is repressed by the Ash1 protein which binds primarily to several sites of the URS1. The TX promoter is primarily regulated by the PGAL upstream activation site (UAS) and a Mig1 repressor protein binding site as well as tandem TetR operator sequences. The TXC and TXC2 are TX-based hybrid promoters containing either both the URS1 and URS2 or just the URS1 region respectively, upstream of the core TX promoter. (B) Diagram of the regulatory network controlling hybrid promoter activation. Hybrid promoter regulatory elements are shown as colored rectangular boxes. Genes are shown as colored arrows. Anhydrous tetracycline (ATc) is inhibiting tetR repression. Ash1 protein is only present in daughter cells.