FIGURE 5.

Drosophila CBP co-activates Caudal-regulated preferential transcriptional activation of the ftz reporter via the N terminus of CBP as well as the HAT domain. A, CBP occupancy at the ftz genomic locus in WT embryos overlaps previously defined Caudal DNA-binding sites. ChIP-sequencing peaks for CBP in 2–4-h-old WT embryos (73) are shown for the ftz locus. Caudal DNA-binding sites that have previously been characterized using DNase I footprinting (45) are shown below. B, schematic representation of the full-length dCBP protein, the dCBP HAT mutant harboring a point mutation (denoted by a star), and the dCBP mutants harboring internal deletions. C, Drosophila S2R+ cells were co-transfected with firefly luciferase reporter constructs driven by the ftz enhancer-promoter containing either an mTATA or mDPE motif as well as plasmids encoding FLAG-Caudal, dCBP, or the indicated dCBP mutants containing either mutation in HAT domain (mutHAT) or internal deletions (marked by Δ). To normalize for variations in transfection efficiency, cells were co-transfected with a Pol III-Renilla luciferase control plasmid and assayed for Dual-Luciferase activity. The activities are reported relative to the activities of the promoters in the absence of co-transfected Caudal or CBP expression plasmids, which were defined to be 1. The graph represents an average of three to four independent experiments. Error bars represent S.E. ns, p > 0.05; *, 0.01 ≤ p ≤ 0.05; **, 0.001 ≤ p ≤ 0.01; ***, p ≤ 0.001. ZnF, zinc finger; Nuc Rec, nuclear receptor coactivator.