Bernd Maurer, Edgar Serfling, Volker ter Meulen, Axel Rethwilm

• The human foamy virus (HFV) contains within the UJ region of its long terminal repeat (L TR) three perfect consensus sequences for the binding of the inducible transcription factor AP-1. Results of DNase I footprint protection and gel retardation assays demonstrated that proteins in extracts of HeLa and BHK-21 cells as weil as bacterially expressed Jun and Fos proteins bind to these AP-1 sites. By conducting transient expression assays using chloramphenicol acetyltransferase plasmids carrying LTR sequences with point-mutated AP-1 sites it wasThe human foamy virus (HFV) contains within the UJ region of its long terminal repeat (L TR) three perfect consensus sequences for the binding of the inducible transcription factor AP-1. Results of DNase I footprint protection and gel retardation assays demonstrated that proteins in extracts of HeLa and BHK-21 cells as weil as bacterially expressed Jun and Fos proteins bind to these AP-1 sites. By conducting transient expression assays using chloramphenicol acetyltransferase plasmids carrying LTR sequences with point-mutated AP-1 sites it was found that the three AP-1 sites contribute to the optimal activity ofthe HFV promoter. It is shown that lnduction of the HFV L TR by 12-O-tetradecanoylphorbol-13-acetate (TPA) and serum factors is mediated through the AP-1 sites.…