Figure 1.

Various DNA-tethered components of the transcriptional machinery can synergize with the HIV-1 activator Tat. All the Pho4 derivatives were expressed from the cytomegalovirus (CMV) enhancer-promoter. The reporter template contained five Pho4-binding sites upstream of the E1B TATA element and a TAR sequence downstream of the start site. DNA (4 μg) encoding Pho4-based effectors was cotransfected with (black bars) or without (white bars) 4 μg of a Tat expression plasmid (also expressed from the CMV enhancer-promoter), 2 μg of the reporter template and, as an internal control, 1 μg of a plasmid encoding lacZ expressed from the CMV promoter. The calcium phosphate precipitation method was used for transfecting HeLa cells with the indicated plasmids. Results of CAT assays are shown.