Transcription elongation factor P-TEFb mediates Tat activation of HIV-1 transcription at multiple stages

摘要: Tat stimulates human immunodeficiency virus type 1 (HIV-1) transcription elongation through recognition of the transactivation response (TAR) RNA stem-loop structure at 5' end nascent viral transcripts. Recently, a factor P-TEFb, consisting CDK9 kinase, cyclin T and other associated factors, has been shown to interact with restore activation in HeLa nuclear extract depleted P-TEFb. Here, we report purification P-TEFb complex fraction containing epitope-tagged wild-type or kinase-inactive five tightly polypeptides. Only an active kinase was able hyperphosphorylate C-terminal domain polymerase II mediate P-TEFb-depleted extract. also stimulated by recruitment HIV-1 promoter Tat-TAR interaction. A possible mechanism for become complexes function as general demonstrated interaction double-stranded molecules 87 kDa subunit. Finally, found phosphorylate Tat-SF1, cofactor required transactivation. Our data indicate that various subunits may play distinct roles multiple stages elongation.