Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chromatin was assembled in vitro from simian virus 40 DNA form I and the calf-thymus four histones H2A, H2B, H3 and H4. Transcription with calf thymus RNA polymerases A and B (I and II) was greatly inhibited. Nucleosomes were found to inhibit both RNA chain initiation and elongation. The inhibition of elongation could be relieved by increasing ionic strength, suggesting that electrostatic interactions between histone octamer and DNA have to be broken for RNA polymerase to transcribe DNA organised into nucleosomes.
...
PMID:Transcription by eukaryotic RNA polymerases A and B of chromatin assembled in vitro. 22 62

Transcription of denatured DNA complexed with histones (total, H1 or H2A/H2B/H3/H4) by yeast RNA polymerase B is investigated. Binding of histones to DNA restricts its template activity by decreasing the formation of active, heparin-resistant, RNA polymerase initiation complexes. The elongation of pre-initiated RNA on denatured DNA, complexed with histones, is possible, although resulting in somewhat shorter RNA chains. It is suggested that RNA polymerase B can elongate on a DNA strand covered with histones.
...
PMID:Transcription of DNA-histone complexes by yeast RNA polymerase B. 35 33

Purified core histones (H2A, H2B, H3, and H4) and bacteriophage T7 DNA have been reconstituted to form a nucleoprotein complex, and the properties of this complex as a template for transcription by Escherichia coli RNA polymerase have been studied. At low ionic strength, RNA chain elongation rates are slow, and the chains produced even after long incubation are short. At higher salt concentrations, chain-elongation rates approach those on naked DNA. Since the salt concentrations used are not in themselves sufficient to dissociate the histones from the DNA, some mechanism must exist that permits passage of the polymerase through histone-covered regions.
...
PMID:Transcription of histone-covered T7 DNA by Escherichia coli RNA polymerase. 36 33

A low-molecular-weight (7000), heat-stable protein--HU--that stimulates transcription of bacteriophage lambda DNA by E. coli RNA polymerase was purified from E. coli extracts using affinity chromatography on DNA-cellulose. HU binds to native DNA, resulting in an apparent thickening of the DNA chains as revealed by electron microscopy. Contrary to DNA unwinding proteins, it causes no destabilization of the double helix. HU differs from previously described transcription factors (H1, D, etc.) and from the low-molecular-weight omega subunit of the RNA polymerase. By its amino-acid composition and characteristics, HU displays an interesting resemblance to some eukaryotic histones, such as H2B and H1.
...
PMID:Characterization of a novel, low-molecular-weight DNA-binding protein from Escherichia coli. 110 48

In vivo UV cross-linking and nuclear transcriptional run-on experiments have shown that a number of Drosophila genes possess an elongationally paused RNA polymerase on their 5' ends. Here, we examine in vivo promoters that do and do not possess paused polymerases using the single-stranded DNA-probing reagent KMnO4. Melted DNA helices are found associated with the pause site of the uninduced hsp70 and hsp26 heat shock genes and the constitutively expressed beta-1 tubulin gene. The histone H1 and H2B genes, which lack a paused polymerase, have no comparable region of melted DNA. Melting at the pause site persists upon heat shock induction of the hsp70 and hsp26 genes, indicating that pausing continues after gene activation. Interestingly, activation triggers additional melting, both at the start site (in the region where open complexes would be expected to form) and downstream of the uninduced pause site. In the course of our studies, we discovered that some T residues of the TATA box were protected from KMnO4 modification in both induced and uninduced cells. This protection appears to be a consequence of TFIID binding, as a similar protection pattern could be produced in vitro with purified protein.
...
PMID:Promoter melting and TFIID complexes on Drosophila genes in vivo. 142 79

By using a DNase I footprinting assay, we have purified a factor by DNA affinity chromatography that binds to the minimal enhancer region of the Drosophila knirps gene and subsequently identified the protein as the core histone H2B. This inadvertent purification of a core histone as a putative sequence-specific DNA binding protein was due to a previously unknown property of H2B to interact with DNA in a periodic manner. Moreover, we found that each of the individual core histones, but not histone H1 or high mobility group protein 1, bound to the knirps enhancer to give a repetitive DNase I footprint pattern with a periodicity of about 10 base pairs, which is approximately one turn of the DNA helix. In addition, preparations containing the core histones H2A-H2B or H3-H4 yielded identical periodic DNase I footprint patterns on several different promoter and enhancer regions. These findings suggest that there are periodic, homotypic interactions between DNA-bound core histones that result from an alteration of the overall DNA structure such as the curvature rather than a specific sequence. We have also shown that histones H2A-H2B can repress initiation of transcription by RNA polymerase II. The phenomena described here may reflect histone-DNA interactions in non-nucleosomal stretches of chromatin and could be involved in some aspects of either rotational or translational positioning of nucleosomes. Furthermore, these findings indicate that a repeated 10 bp DNase I ladder, which has previously been considered to be a property of an intact nucleosome, can also be generated with subnucleosomal components. It will thus be necessary to reevaluate the criteria applied to the analysis of nucleosomes both in vivo and in vitro.
...
PMID:Periodic binding of individual core histones to DNA: inadvertent purification of the core histone H2B as a putative enhancer-binding factor. 148 Apr 89

Binding of high mobility group (HMG) proteins 14 and 17 (HMG 14/17) to complete nucleosomal cores and to cores lacking one H2A.H2B dimer, the amino-terminal tails of histones, or both one H2A.H2B dimer and the amino-terminal ends of histones is accompanied by an overall stabilization of the particles as determined by thermal denaturation, circular dichroism and DNase I digestion. In spite of the structural stabilization brought about by HMG 14/17, the presence of these proteins causes little effect on the efficiency of the different nucleosomal particles as transcription templates for RNA polymerase II. The nucleosomal particles lacking one H2A.H2B dimer and containing two bound HMG 14/17 molecules are efficient in vitro transcription templates, which allow transcription of the whole length of the DNA present in the particle. These results are consistent with HMG 14/17 being present in active chromatin.
...
PMID:Structural and transcriptional properties of different nucleosomal particles containing high mobility group proteins 14 and 17 (HMG 14/17). 169 25

Histones have been both radiolabeled and density-labeled with amino acids in vivo to determine the dynamics of histone-DNA and histone-histone interactions at the replication fork and on active genes. Proteins were uniformly labeled and subsequently chased for three cell generations. During the chase period, H3,H4 tetramers dissociated from the H2A,H2B dimers to re-form nucleosomes with the corresponding nondense histones synthesized during the chase period. These data suggest that the prereplicative nucleosomes are dissolved during advancement of the replication fork with release of associated histones in the form of the H3,H4 tetramers and H2A,H2B dimers. Experiments that involve density labeling of cells in the presence of actinomycin D indicate that the dynamic exchange of H2A,H2B that has been previously described [Jackson, V. (1987) Biochemistry 26, 2315-2324] is partially dependent on RNA polymerase movement. These results provide indirect evidence that nucleosome dissolution occurs during transcription. When deposition during replication and transcription is inhibited by simultaneous treatment of cells with cytosine arabinoside and actinomycin D, the majority of the newly synthesized histones are unable to deposit into nucleosome structure. The low level of deposition that is observed has characteristics similar to the deposition of uH2A and uH2B, and it is proposed that conjugation of H2A and H2B by ubiquitin occurs when these proteins are in a free pool within the nucleus. The new H3,H4 tetramers and new H2A,H2B dimers when prevented from depositing are not stable. New and old H3 and H4 intermix to form hybrid tetramers, and a similar intermixing is observed for the H2A,H2B dimers. A model is presented to describe the dynamics of histone-DNA interactions during replication and transcription.
...
PMID:In vivo studies on the dynamics of histone-DNA interaction: evidence for nucleosome dissolution during replication and transcription and a low level of dissolution independent of both. 169 79

Nucleosomal particles lacking one H2A.H2B dimer interact with RNA polymerase from Escherichia coli more strongly than the complete nucleosomal core particles. Moreover, the in vitro transcription of the H2A.H2B-deficient particles is much more efficient than that of the whole nucleosomal cores, both in the presence and absence of rifampicin. Although a substantial fraction of particles in the preparation of whole nucleosomal cores binds to RNA polymerase, the efficiency of these particles as transcription templates is very small. This block to transcription is partially eliminated when one H2A.H2B dimer is released from the core particle. Our results suggest that the lack of one H2A.H2B dimer from nucleosomal particles might be required for the formation of complexes with RNA polymerase active in transcription.
...
PMID:Interaction with RNA polymerase of nucleosomal cores lacking one H2A.H2B dimer. 244 Aug 88

The loss of one H2A.H2B dimer from the nucleosomal core increases its affinity for RNA polymerase II and its efficiency as a transcription template, allowing transcription of the entire DNA present in the particle. In contrast, the nucleosomal core lacking the amino-terminal ends of histones, which has an affinity for polymerase equal to that of the H2A.H2B-deficient core, shows transcription properties similar to those of the whole nucleosomal core, with synthesis of short RNA chains (40 nucleotides or less). Similar results were obtained with a bacterial RNA polymerase. The improved efficiency of the H2A.H2B-deficient cores as transcription templates does not appear to be produced by nonspecific loss of protein or structural relaxation of the particle. These results suggest that a particle lacking one H2A.H2B dimer might be a necessary intermediate during in vivo transcription.
...
PMID:Interaction of RNA polymerase II with structurally altered nucleosomal particles. Transcription is facilitated by loss of one H2A.H2B dimer. 247 45


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

---