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)

Chick liver nuclear 5.0 S RNA, which stimulates RNA synthesis on chromatin, binds preferentially to the deoxyribonucleoprotein in homologous chromatin. The proteins found in the isolated deoxyribonucleoprotein-5.0 S RNA complex are total amount of both H4 and H3 histone, about 20% of nonhistone protein and about 50% of both H2a and H2b histone found in the original chromatin. Cesium chloride equilibrium centrifugation of the deoxyribonucleoprotein-5.0 S RNA complex after fixation with formaldehyde shows that the 5.0 S RNA is bound to certain proteins (acid-soluble and -insoluble) in the complex. The stimulation of RNA synthesis by the nuclear RNA fraction is due to the conversion of inaccessible region of DNA to RNA polymerase into an accessible one and presumably not due to an increase in the number of binding sites for RNA polymerase in the chromatin. The release of non-histone protein from chromatin following the addition of the nuclear RNA fraction is also briefly discussed.
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PMID:Interaction of chromatin components with nuclear 5.0 S RNA fraction that stimulates RNA synthesis. 92 98

Simian virus 40 (SV40) virions were dissociated in vitro by treatment with ethylene glycol-bis-N-N'-tetraacetic acid and dithiothreitol. The compact nucleo-protein core released as a result of the dissociation had a sedimentation value of 110 to 115S compared with a value of 240S for intact virions. The viral cores contained a fraction of the viral proteins VP(1) and VP(2) in addition to the proteins found associated with the viral minichromosome, i.e., VP(3) and histones H(2)A, H(2)B, H(3), and H(4). Our results suggest that the association of VP(1), VP(2), or both with the viral minichromosome, in addition to maintaining a highly compact structure, modifies the transcriptional properties of the nucleoprotein complex. In the presence of saturating amounts of Escherichia coli RNA polymerase, 95 to 100% of the SV40 nucleoprotein cores were able to form transcriptional complexes. Sedimentation analysis of the core transcriptional complex indicated that the initiation and elongation of nascent RNA chains occurred on the compact SV40 core. Cesium chloride density gradient analysis of the SV40 virion core before and after transcription indicated that no substantial loss of protein occurred during the process of transcription. RNA synthesized from SV40 cores was a fairly homogeneous 16 to 18S species with an average chain length of approximately 2,300 nucleotides. Hybridization analysis of this RNA indicated that specific recognition of RNA polymerase promoter sites was preserved, since transcription was asymmetric, occurring preferentially on the "early" SV40 DNA strand. The rate of incorporation of ribonucleoside triphosphates into acid-insoluble RNA with SV40 cores as the template was 70 to 95% of that obtained with supercoiled SV40 form I DNA. SV40 minichromosomes, under identical transcription assay conditions, had an incorporation rate which was 20% of that obtained with SV40 form I DNA. These results show that association of protein VP(1) or VP(2) or both enhances the transcriptional activity and suggest that these "late" viral proteins may play a role in the regulation of expression of the SV40 genome.
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PMID:Efficient transcription of a compact nucleoprotein complex isolated from purified simian virus 40 virions. 625 78

A DNA containing bacteriophage, Kvp1, was isolated from the water of a very polluted river, the Matanza river, near the central district of Buenos Aires City. This bacteriophage infects bacteria belonging to the Kluyvera cryocrescens species (strain 21 g) isolated from the same river. Kvp1 is a lytic bacteriophage and its propagation characteristics are: burst size 30, latent period 13 min and rise period 10 min. Morphologically, Kvp1 is a small icosahedral bacteriophage, 59.1 nm in diameter, which possesses a short wedge-shaped tail. Its buoyant density in ClCs is 1.517 g/cm3. Kvp1 DNA is linear, double stranded and approximately 40,000 bp in size. The viral particle is composed of at least nine proteins. SDS-PAGE patterns of these proteins and of those produced during the host infection, in addition to its morphological and genomic characteristics, suggested that Kvp1 is similar to the coliphage T7. Molecular cloning, sequencing and computer-assisted analysis of Kvp1 DNA fragments confirmed the relationship to the coliphage. Taking this into account, the partial sequence of the phage RNA polymerase was used to construct phylogenetic relationships between Kvp1 and other related phages. To our knowledge, Kvp1 is the first bacteriophage described which uses as host a member of the Kluyvera bacterial genus.
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PMID:Kluyvera bacteriophage Kvp1: a new member of the Podoviridae family phylogenetically related to the coliphage T7. 938 94