Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20226 (TATA-binding protein)
 1,297 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transcriptional activation domain of the herpesvirus protein VP16 resides in the carboxyl-terminal 78 amino acids (residues 413-490). Fluorescence analyses of this domain indicated that critical amino acids are solvent-exposed in highly mobile segments. To examine interactions between VP16 and components of the basal transcriptional machinery, we incorporated (at position 442 or 473 of VP16) tryptophan analogs that can be selectively excited in complexes with other Trp-containing proteins. TATA-box binding protein (TBP) (but not transcription factor B (TFIIB)) caused concentration-dependent changes in the steady-state anisotropy of VP16, from which equilibrium binding constants were calculated. Quenching of the fluorescence from either position (442 or 473) was significantly affected by TBP, whereas TFIIB affected quenching only at position 473. 7-aza-Trp residues at either position showed a emission spectral shift in the presence of TBP (but not TFIIB), indicating a change to a more hydrophobic environment. In anisotropy decay experiments, TBP reduced the segmental motion at either position; in contrast, TFIIB induced a slight change only at position 473. Our results support models of TBP as a target protein for transcriptional activators and suggest that ordered structure in the VP16 activation domain is induced upon interaction with target proteins.
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PMID:Transcriptional activation domain of the herpesvirus protein VP16 becomes conformationally constrained upon interaction with basal transcription factors. 861 52

The association of monomeric TATA binding protein with promoter DNA is an essential first step in many current models of eukaryotic transcription initiation. This step is followed by others in which additional transcription factors, and finally RNA polymerase, assemble at the promoter. Here we characterize the quaternary interactions of the Saccharomyces cerevisiae TATA-binding protein (yTBP), in the absence of other proteins or DNA. The data reveal a robust pattern in which yTBP monomers equilibrate with tetramers and octamers over a broad span of temperatures (4 degrees C </= T </= 37 degrees C) and salt concentrations (60 mM </= [KCl] </= 1 M), that includes the physiological range. Association is highly cooperative, with octamer formation favored by approximately 9 kcal/mol over tetramer formation. Changes in association constant with [KCl] are consistent with an assembly-linked release of ions at low salt and an assembly-linked uptake of ions at high salt, for both monomer right arrow over left arrow tetramer and tetramer right arrow over left arrow octamer reaction steps. Fluorescence emission spectra and steady-state anisotropies reveal that the amino-terminal domain changes conformation and dynamics at both association steps and that the polarity of the environment near tryptophan 26 is sensitive to changes in [KCl] in the monomeric and tetrameric states but not the octameric state. These results are consistent with a [salt]-dependent change in the assembly mechanism near 300 mM KCl and suggest that the amino-terminal domain may modulate the self-association of the full-length protein. TBP self-association may regulate many of its cellular functions, including transit of the nuclear membrane and participation in transcription initiation.
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PMID:Participation of the amino-terminal domain in the self-association of the full-length yeast TATA binding protein. 1076 45

Transcription of archaeal non-stress genes involves the basal factors TBP and TFB, homologs of the eucaryal TATA-binding protein and transcription factor IIB, respectively. No comparable information exists for the archaeal molecular-chaperone, stress genes hsp70(dnaK), hsp40(dnaJ), and grpE. These do not occur in some archaeal species, but are present in others possibly due to lateral transfer from bacteria, which provides a unique opportunity to study regulation of stress-inducible bacterial genes in organisms with eukaryotic-like transcription machinery. Among the Archaea with the genes, those from the mesophilic methanogen Methanosarcina mazeii are the only ones whose basal (constitutive) and stress-induced transcription patterns have been determined. To continue this work, tbp and tfb were cloned from M. mazeii, sequenced, and the encoded recombinant proteins characterized in solution, separately and in complex with each other and with DNA. M. mazeii TBP ranks among the shortest within Archaea and, contrary to other archaeal TBPs, it lacks tryptophan or an acidic tail at the C terminus and has a basic N-terminal third. M. mazeii TFB is similar in length to archaeal and eucaryal homologs and all have a zinc finger and HTH motifs. Phylogenetically, the archaeal and eucaryal proteins form separate clusters and the M. mazeii molecules are closer to the homologs from Archaeoglobus fulgidus than to any other. Antigenically, M. mazeii TBP and TFB are close to archaeal homologs within each factor family, but the two families are unrelated. The purified recombinant factors were functionally active in a cell-free in vitro transcription system, and were interchangeable with the homologs from Methanococcus thermolithotrophicus. The M. mazeii factors have a similar secondary structure by circular dichroism (CD). The CD spectra changed upon binding to the promoters of the stress genes grpE, dnaK, and dnaJ, with the changes being distinctive for each promoter; in contrast, no effect was produced by the promoter of a non-stress-gene. Factor(s)-DNA modeling predicted that modifications of H bonds are caused by TBP binding, and that these modifications are distinctive for each promoter. It also showed which amino acid residues would contact an extended TATA box with a B recognition element, and evolutionary conservation of the TBP-TFB-DNA complex orientation between two archaeal organisms with widely different optimal temperature for growth (37 and 100 degrees C).
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PMID:The basal transcription factors TBP and TFB from the mesophilic archaeon Methanosarcina mazeii: structure and conformational changes upon interaction with stress-gene promoters. 1139 82

The aryl hydrocarbon receptor (AhR) is an intracellular receptor protein that regulates gene transcription in response to both man-made and natural ligands. A modular transactivaton domain (TAD) has been mapped to the 304 C-terminal amino acids and consists of acidic, Q-rich, and P/S/T-rich subdomains. We have used steady-state intrinsic tryptophan fluorescence and circular dichroism spectroscopy to investigate the conformation of the acidic Q-rich region. The results reveal that this region of the protein is structurally flexible but adopts a more folded conformation in the presence of the natural osmolyte trimethylamine N-oxide (TMAO) and the solvent trifluoroethanol (TFE). In protein-protein interaction studies, the acidic Q-rich region bound to components of the general transcription machinery [TATA-binding protein (TBP), TAF4, and TAF6] as well as the coactivator proteins SRC-1a and TIF2. The binding site for TBP mapped to the acidic subdomain, while SRC-1a bound preferentially to the Q-rich sequence. Significantly, the binding of TBP was modulated by induced folding of the TAD with TMAO. The results indicate that the AhR TAD makes multiple interactions with the transcriptional machinery and protein conformation plays a critical role in receptor function. Taken together, these findings support a role for protein folding in AhR action and suggest possible mechanisms of receptor-dependent gene activation.
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PMID:Induced alpha-helix structure in the aryl hydrocarbon receptor transactivation domain modulates protein-protein interactions. 1564