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Query: UNIPROT:P20226 (TATA-binding protein)
 1,297 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human immunodeficiency virus type 1 (HIV-1) is viable and mitogen inducible in the absence of its binding sites for the inducible transcription factor NF-kappa B. We have investigated alternative mechanisms for induction of HIV-1 transcription. Using transient transfection assays, we found that transcription from an HIV-1 LTR containing mutant kappa B sites was activated 10- to 20-fold in a variety of human cell types by the phorbol ester phorbol myristate acetate (PMA). The promoter elements conferring this inducibility were localized to the region downstream of nucleotide -70, which contains the TATA and TAR elements and binding sites for transcription factors Sp1 and LBP-1. Synthetic promoters containing only Sp1 sites and a TATA element were also induced in transfection experiments as well as in in vitro transcription experiments with T-cell nuclear extracts. Moreover, promoters containing a TATA box in the absence of Sp1 sites or Sp1 sites in the absence of a TATA box were equally inducible in vitro, as was an RNA polymerase III promoter. The activities of RNA polymerases II and III and of the 38-kDa TATA-binding protein transcription factor IID (TFIID), were not induced by PMA, but electrophoretic mobility shift assays revealed a highly inducible protein-DNA complex that interacted specifically with the TATA sequence. This protein-DNA complex appeared to be much larger than that found with the 38-kDa human TFIID expressed in bacteria. Taken together, these data suggest that a component of the general transcription machinery, and possibly a TFIID-associated protein, is induced in T cells by PMA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alternative pathway for induction of human immunodeficiency virus gene expression: involvement of the general transcription machinery. 189 93

The HIV-1 (human immunodeficiency virus type 1) and HIV-2 Tat proteins increase the level of transcription from their corresponding long terminal repeats. Tat activates transcription likely by interaction with components of the transcriptional initiation and elongation complexes during different stages of the transcription reaction. In the current study, two approaches were used to address the sites at which Tat becomes stably associated with the HIV transcription complex. First, we isolated column purified HIV-1 and HIV-2 transcription complexes that were competent for in vitro transcription and found that wild-type but not mutant Tat protein was specifically associated with this complex. An intact HIV TATA element and the presence of functional TATA-binding protein were necessary for Tat association. In contrast, the HIV-1 and HIV-2 TAR bulge sequences which serve as binding sites for Tat were not required for its association with the HIV preinitiation complex. A second complementary approach using immobilized HIV-1 and HIV-2 templates also demonstrated a functional association of Tat with HIV-1 and HIV-2 preinitiation complexes. Wild-type but not mutant Tat proteins associated with transcription complexes assembled on immobilized HIV-1 and HIV-2 templates and the association of Tat correlated with increases in the level of in vitro transcription. These results indicate that Tat can associate with HIV-1 and HIV-2 transcription complexes prior to the initiation of transcription by RNA polymerase II.
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PMID:Association of Tat with purified HIV-1 and HIV-2 transcription preinitiation complexes. 905 83

Artificial recruitment of TATA-binding protein (TBP) to many eukaryotic promoters bypasses DNA-bound activator function. The human immunodeficiency virus type 1 (HIV-1) Tat is an unconventional activator that up-regulates transcription from the HIV-1 long terminal repeat (LTR) through binding to a nascent RNA sequence, TAR. Because this LTR and its cognate activator have atypical features compared to a standard RNA polymerase II (RNAP II) transcriptional unit, the precise limiting steps for HIV-1 transcription and how Tat resolves these limitations remain incompletely understood. We thus constructed human TBP fused to the DNA-binding domain of GAL4 to determine whether recruitment of TBP is one rate-limiting step in HIV-1 LTR transcription and whether Tat functions to recruit TBP. As a control, we compared the activity of the adenovirus E1b promoter. Our findings indicate that TBP tethering to the E1b promoter fully effected transcription to the same degree achievable with the potent GAL4-VP16 activator. By contrast, TBP recruitment to the HIV-1 LTR, although necessary for conferring Tat responsiveness, did not bypass a physical need for Tat in achieving activated transcription. These results document that the HIV-1 and the E1b promoters are transcriptionally limited at different steps; the major rate-limiting step for E1b is recruitment of TBP, while activation of the HIV-1 LTR requires steps in addition to TBP recruitment. We suggest that Tat acts to accelerate rate-limiting steps after TBP recruitment.
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PMID:Promoter activity of Tat at steps subsequent to TATA-binding protein recruitment. 937 21