Figure 3.
“Calling cards” for DNA-binding proteins. For each of seven transcription factors fused to Sir4 (Gal4, Gal80, Ste12, Bas1, Pho2, Gcn4, and Pho4), a unique 20-bp oligonucleotide was inserted into Ty5 to serve as a “molecular bar code,” thereby transforming Ty5 into a “calling card” that the TF leaves behind when it visits a site in the genome. Each strain was cotransformed with a plasmid encoding a TF-Sir4 fusion and a plasmid carrying its matched Ty5 calling card. After transposition, the calling cards deposited in the promoters of interest were recovered by a PCR with Ty5- and promoter-specific primers.
