Transcription factor AP-2 regulates human immunodeficiency virus type 1 gene expression

Human immunodeficiency virus type 1 (HIV-1) gene expression is regulated by an enhancer region composed of multiple potential cis-acting regulatory sites. Here, we describe binding sites for the transcription factor AP-2 in the HIV-1 long terminal repeat which modulate HIV enhancer function. One site is embedded within the two previously described κB elements, and a second site is detected further downstream. DNase I footprinting and electrophoretic mobility shift assay experiments demonstrated that AP-2 binds to the site between the κB elements. Interestingly, AP-2 and NF-κB bind to this region in a mutually exclusive manner. Mutations which disrupt this AP-2-binding site lower basal levels of transcription but do not affect NF-κB-mediated induction by tumor necrosis factor alpha in Jurkat T leukemia cells.