Tat-SF1 protein associates with RAP30 and human SPT5 proteins.
The potent transactivator Tat recognizes the transactivation response RNA element (TAR) of human immunodeficiency virus type 1 and stimulates the processivity of elongation of RNA polymerase (Pol) II complexes. The cellular proteins Tat-SF1 and human SPT5 (hSPT5) are required for Tat activation as shown by immunodepletion with specific sera and complementation with recombinant proteins. In nuclear extracts, small fractions of both hSPT5 and Pol II are associated with Tat-SF1 protein. Surprisingly, the RAP30 protein of the heterodimeric transcription TFIIF factor is associated with Tat-SF1, while the RAP74 subunit of TFIIF is not coimmunoprecipitated with Tat-SF1. Overexpression of Tat-SF1 and hSPT5 specifically stimulates the transcriptional activity of Tat in vivo. These results suggest that Tat-SF1 and hSPT5 are indispensable cellular factors supporting Tat-specific transcription activation and that they may interact with RAP30 in controlling elongation.
Kim
J B
JB
Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Yamaguchi
Y
Y
Wada
T
T
Handa
H
H
Sharp
P A
PA
D002868:Chromosomal Proteins, Non-Histone; D004257:DNA Polymerase II / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII; D015533:Transcriptional Activation; D035602:Transcriptional Elongation Factors
D002868:Chromosomal Proteins, Non-Histone; D005656:Fungal Proteins; C101819:HTATSF1 protein, human; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D035602:Transcriptional Elongation Factors; C069940:SPT5 transcriptional elongation factor; D004257:DNA Polymerase II; C056604:transcription factor TFIIF