Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A transcriptional initiator (Inr) for mammalian RNA polymerase II can be defined as a DNA sequence element that overlaps a transcription start site and is sufficient for (i) determining the start site location in a promoter that lacks a TATA box and (ii) enhancing the strength of a promoter that contains a TATA box. We have prepared synthetic promoters containing random nucleotides downstream of Sp1 binding sites to determine the range of DNA sequences that convey Inr activity. Numerous sequences behaved as functional Inrs in an in vitro transcription assay, but the Inr activities varied dramatically. An examination of the functional elements revealed loose but consistent sequence requirements, with the approximate consensus sequence Py Py A+1 N T/A Py Py. Most importantly, almost every functional Inr that has been described fits into the consensus sequence that we have defined. Although several proteins have been reported to bind to specific Inrs, manipulation of those elements failed to correlate protein binding with Inr activity. The simplest model to explain these results is that all or most Inrs are recognized by a universal binding protein, similar to the functional recognition of all TATA sequences by the same TATA-binding protein. The previously reported proteins that bind near specific Inr elements may augment the strength of an Inr or may impart transcriptional regulation through an Inr.
 ...
PMID:DNA sequence requirements for transcriptional initiator activity in mammalian cells. 826 80

Activation domains of mammalian transcription factors can be subdivided into at least two functional classes. One, exemplified by the glutamine-rich activation domains of Oct and Sp1 factors, mediates transcriptional activation only from a proximal promoter position, and in response to an enhancer. The other, exemplified by the 'acidic' domain of the viral activator VP16, has the ability to activate from remote enhancer as well as from proximal promoter positions. Here we report that two proteins of the basal transcription apparatus also contain activation domains whose stimulatory effect can be detected in fusion proteins containing the GAL4 DNA binding domain. The human TATA-binding protein (TBP) contains at its N-terminus a domain with typical 'promoter' activity. We propose that the TBP N-terminal region acts as an auxiliary activation domain which reinforces the activity of other promoter-bound factors. The largest subunit of RNA polymerase II contains at its C-terminus a conserved heptad repeat structure (CTD). Both natural and synthetic CTD consensus repeats fused to GAL4 can activate transcription from remote positions like a typical enhancer-active domain. Accordingly we propose that the RNA polymerase II large subunit contains a 'portable' domain for transcriptional activation which may synergize with the activation domains of enhancer-bound transcription factors.
 ...
PMID:C-terminal domain (CTD) of RNA-polymerase II and N-terminal segment of the human TATA binding protein (TBP) can mediate remote and proximal transcriptional activation, respectively. 828 5

DNA-activated protein kinase (DNA-PK) is a nuclear serine/threonine protein kinase that is activated in vitro by DNA fragments. The cellular targets of DNA-PK are nuclear, DNA-binding, regulatory proteins including Sp1, Fos, Jun, Myc, the tumor suppressor protein p53, and RNA polymerase II. These characteristics suggest a role for DNA-PK in coordinating nuclear processes and as a modulator of checkpoint mechanisms activated by DNA damage.
 ...
PMID:DNA damage and the DNA-activated protein kinase. 829 Oct 90

We have fused representatives of three structurally and functionally distinct classes of mammalian transcription activation domains for RNA polymerase II to the yeast GAL4 DNA binding domain. All fusion proteins were stable when expressed in yeast and were tested for their ability to activate transcription from various positions in the yeast GAL1 promoter. Activation domains functional from remote as well as TATA-proximal positions in mammalian cells, e.g. the acidic-type domain of VP16, also stimulate transcription in yeast from various promoter positions. Proline-rich domains, as e.g. in AP-2 and CTF/NF1, with considerable promoter activity and low enhancer activity in mammalian cells stimulate transcription in yeast only from a position close to the TATA box. The glutamine-rich domains of Oct1, Oct2 and Sp1, which activate transcription in mammalian cells from close to the TATA box in response to a remote enhancer, are inactive in the yeast GAL1 promoter. This finding might reflect some basic difference between the organization of yeast and mammalian promoters.
 ...
PMID:Functional differences between mammalian transcription activation domains at the yeast GAL1 promoter. 831 9

Transcription factor Sp1, which has a DNA binding domain composed of three zinc fingers, binds to GC box (consensus sequence, G/T-GGGCGG-G/A-G/A-C/T) and activates the transcription by RNA polymerase II. Metal substitution of nickel(II) for zinc(II) in Sp1 causes no differences in the mode of protein-DNA interaction. However, sequence preference of Ni(II)Sp1 changes from 5'-GGGGCGGGGC to 5'-GGGGCGTGGC, and is distinct from that of Zn(II)Sp1. The result indicates an important effect of metal-induced folding on sequence-specific recognition of DNA by zinc-finger proteins.
 ...
PMID:Alteration of DNA binding specificity by nickel (II) substitution in three zinc (II) fingers of transcription factor Sp1. 835 9

A key component of the RNA polymerase II transcriptional apparatus, TFIID, is a multi-protein complex containing the TATA box-binding protein (TBP) and at least seven tightly associated factors (TAFs). Although the functions of most TFIID subunits are unknown, it is clear that TAFs are not necessary for basal activity but that one or more are required for regulated transcription, and so behave as coactivators. The presence of multiple subunits indicates that there is an intricate assembly process and that TAFs may be responsible for other activities. We have described the properties of the subunit dTAFII110, which can interact directly with the transcriptional activator Sp1 (ref. 5). In addition, the largest subunit, dTAFII250, binds directly to TBP and links other TAFs to the complex. Here we describe the cloning, expression and partial characterization of the Drosophila TAF of M(r) 80,000, dTAFII80. Sequence analysis reveals that dTAFII80 contains several copies of the WD40 (beta-transducin) repeat. Moreover, dTAFII80 shares extended sequence similarity with an Arabidopsis gene, COP1, which encodes a putative transcription factor that is though to regulate development. We have expressed recombinant dTAFII80 and begun to characterize its interaction with other members of the TFIID complex. Purified recombinant dTAFII80 is unable to bind TBP directly or to interact strongly with the C-terminal domain of dTAFII250 (delta N250). Instead, dTAFII80 is only able to recognize and interact with a higher-order complex containing TBP, delta N250, 110 and 60. These findings suggest the formation of TFIID may require an ordered assembly of the TAFs, some of which bind directly to TBP and others that are tethered to the complex as a result of specific TAF/TAF interactions.
 ...
PMID:The dTAFII80 subunit of Drosophila TFIID contains beta-transducin repeats. 848 3

Simian virus 40 (SV40) large T antigen (Tag) is a promiscuous transcriptional transactivator; however, its mechanism of transactivation remains unknown. Recent studies have suggested the possible involvement of protein-protein interactions with TBP, the TATA box-binding protein of TFIID, and TEF-1, an enhancer-binding factor. We show here that (i) the Tag domain containing amino acids 133 to 249 directly interacts with the general transcription factor TFIIB, the activator protein Sp1, and the 140-kDa subunit of RNA polymerase II, as well as with TBP and TEF-1; (ii) these interactions can also occur when these transcription factors are present in their functional states in cellular extracts; (iii) binding of Tag to TBP is eliminated by preincubation of TBP either at 48 degrees C or with the adenovirus 13S E1a protein; (iv) this domain of Tag cannot bind concurrently to more than one of these transcription factors; and (v) the substitution of Tag amino acid residues 173 and 174 inactivates the ability of this Tag domain both to associate with any of these transcription factors and to transactivate the SV40 late promoter. Thus, we conclude that SV40 Tag probably does not transactivate via the concurrent interaction with multiple components of the preinitiation complex. Rather, we hypothesize that transactivation by Tag may primarily occur by removing or preventing the binding of factors that inhibit the formation of preinitiation complexes.
 ...
PMID:The major transcriptional transactivation domain of simian virus 40 large T antigen associates nonconcurrently with multiple components of the transcriptional preinitiation complex. 855 80

NF-kappa B is a potent inducible transcription factor that regulates many genes in activated T cells. In this report we examined the ability of different subunits of NF-kappa B to enhance HIV-1 transcription in vitro with chromatin templates. We find that the p65 subunit of NF-kappa B is a strong transcriptional activator of nucleosome-assembled HIV-1 DNA, whereas p50 does not activate transcription, and that p65 activates transcription synergistically with Sp1 and distal HIV-1 enhancer-binding factors (LEF-1, Ets-1, and TFE-3). These effects were observed with chromatin, but not with nonchromatin templates. Furthermore, binding of either p50 or p65 with Sp1 induces rearrangement of the chromatin to a structure that resembles the one reported previously for integrated HIV-1 proviral DNA in vivo. These results suggest that p50 and Sp1 contribute to the establishment of the nucleosomal arrangement of the uninduced provirus in resting T cells, and that p65 activates transcription by recruitment of the RNA polymerase II transcriptional machinery to the chromatin-repressed basal promoter.
 ...
PMID:NF-kappa B-mediated chromatin reconfiguration and transcriptional activation of the HIV-1 enhancer in vitro. 855 93

We have studied the abilities of different transactivation domains to stimulate the initiation and elongation (postinitiation) steps of RNA polymerase II transcription in vivo. Nuclear run-on and RNase protection analyses revealed three classes of activation domains: Sp1 and CTF stimulated initiation (type I); human immunodeficiency virus type 1 Tat fused to a DNA binding domain stimulated predominantly elongation (type IIA); and VP16, p53, and E2F1 stimulated both initiation and elongation (type IIB). A quadruple point mutation of VP16 converted it from a type IIB to a type I activator. Type I and type IIA activators synergized with one another but not with type IIB activators. This observation implies that synergy can result from the concerted action of factors stimulating two different steps in transcription: initiation and elongation. The functional differences between activators may be explained by the different contacts they make with general transcription factors. In support of this idea, we found a correlation between the abilities of activators, including Tat, to stimulate elongation and their abilities to bind TFIIH.
 ...
PMID:Three functional classes of transcriptional activation domain. 862 70

Adeno-associated virus (AAV) Rep78 is a multifunctional protein that is required for AAV transcriptional activity, AAV DNA replication, and possibly for site-specific integration of AAV into human chromosome 19. Rep78 is also able to inhibit a variety of heterologous promoters, including those of c-H-ras, human papillomavirus types 16 and 18, and HIV type 1. However, Rep78 is unable to significantly affect murine osteosarcomavirus (MSV). It was noticed that promoters that are inhibited possess binding motifs for the cellular transcription factor Sp1, whereas the MSV long terminal repeat promoter did not. These data stimulated the hypothesis that Rep78 may recognize and interact with cellular Sp1. Here, we demonstrate that Rep78 is able to interact with Sp1 in vitro as analyzed by West(far)-Western, electrophoretic mobility shift assay-supershift, and coimmunoprecipitation analyses. Furthermore, in support of an in vivo biological effect from this interaction, Rep78 is demonstrated to inhibit a synthetic, Sp1-dependent promoter. Further still, the insertion of Sp1 DNA binding motifs into the Rep78-resistant MSV long terminal repeat results in a promoter that has increased sensitivity to inhibition by Rep78. Finally, it is demonstrated that the Sp1-Rep78 interaction requires the amino half of Rep78. The interaction of Rep78 with Sp1, along with possible downstream effects on the transcription initiation process of RNA polymerase II, may partially explain the rather broad-based antitumor abilities of AAV.
 ...
PMID:The adeno-associated virus Rep78 major regulatory/transformation suppressor protein binds cellular Sp1 in vitro and evidence of a biological effect. 891 72


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>