DIRECT INTERACTION OF HUMAN TFIID WITH THE HIV-1 TRANSACTIVATOR TAT

THE tat gene of the human immunodeficiency virus (HIV) plays a central role in the activation and life cycle of HIV. The tat protein (Tat) s pecifically transactivates HIV transcription in vivo and in vitro1-8, exerting its effects at the level of transcriptional initiation and el ongation. Here we report that Tat binds directly to the basal transcri ption factor TFIID. The transcriptional activity of HeLa extracts was depleted after chromatography on a rat affinity column, which specific ally retained the polymerase II-specific factor TFIID: Direct interact ion of Tat with holo-TFIID, composed of TATA-binding protein (TBP) and associated factors (TAFs), was observed. Tat binds, through amino aci ds 36-50, directly to the TBP subunit of TFIID. Our results suggest th at Tat may transduce upstream or downstream regulatory signals by dire ct interaction with the basal transcription factor TFIID.