Evidence for functional interaction between the HIV-1 Tat transactivator and the TATA box binding protein in vivo.

摘要: Tat strongly activates transcription of the HIV-1 provirus by stimulating both initiation and elongation. This transactivator binds to TAR RNA element, but can also associate with cellular factors, interacting upstream promoter sequences. To achieve a better understanding role in assembly transcriptional complex living cell, we have examined how activity this protein is modified when general factor involved first step process, TBP, overexpressed. The Tat, either wild-type or fused DNA binding domain GAL4 (GBTat), was tested using reporter constructs containing sites minimal corresponding TATA box, without element. We found that overexpression TBP led dramatic increase GBTat protein. In order activate GBTat, must be able interact box. Analysis several mutants indicated cysteine-rich core domains are necessary sufficient vitro experiments showed specifically TBP. There correlation between ability different bind their capacity vivo. With natural promoter, stimulated then suppressed Tat-induced activity. inhibition abrogated an intracellular levels Tat. These experimental data indicate stimulates