Role of the human homolog of the yeast transcription factor SPT5 in HIV-1 Tat-activation.
The transactivator protein Tat stimulates transcriptional elongation from the HIV-1 LTR. One mechanism by which Tat increases HIV-1 transcription is by interacting with RNA polymerase II and TFIIH to increase phosphorylation of the polymerase C-terminal domain. Recent studies indicate that specific elongation factors may also be required to modulate Tat function. Here, we used biochemical analysis and in vitro transcription assays to identify cellular factors required for Tat activation. This analysis resulted in the purification of a cellular factor Tat-CT1 which is a human homolog of the yeast transcription factor SPT5. Immunodepletion of Tat-CTl from HeLa extract demonstrated that this factor was involved in transcriptional activation by Tat. However, the absence of this factor from HeLa extract did not prevent transcriptional activation by VP16. These findings are consistent with a model in which Tat-mediated effects on transcriptional elongation are mediated in part by the action of the human homolog of the yeast transcription factor SPT5.
Wu-Baer
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Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75235-8594, USA.
Lane
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Gaynor
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D000595:Amino Acid Sequence; D002852:Chromatography, Ion Exchange; D002868:Chromosomal Proteins, Non-Histone; D018076:DNA, Complementary; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000378:metabolism*; D015696:Gene Products, tat / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006367:HeLa Cells; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D016366:Open Reading Frames; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D035602:Transcriptional Elongation Factors; D054322:tat Gene Products, Human Immunodeficiency Virus
D002868:Chromosomal Proteins, Non-Histone; D018076:DNA, Complementary; D005656:Fungal Proteins; D015696:Gene Products, tat; D017405:Herpes Simplex Virus Protein Vmw65; D009687:Nuclear Proteins; C112224:SUPT5H protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D054322:tat Gene Products, Human Immunodeficiency Virus; C069940:SPT5 transcriptional elongation factor