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

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

The influenza virus NS1 protein was shown to stimulate translation of the M1 protein. M-CAT RNA, which contains the chloramphenicol acetyltransferase (CAT) reporter gene and the terminal noncoding sequence of segment 7 (coding for the M1 and M2 proteins), was ribonucleoprotein transfected into clone 76 cells expressing the influenza virus RNA polymerase and NP proteins required for the transcription and replication of influenza virus ribonucleoproteins. When the cells were superinfected with a recombinant vaccinia virus which expresses the NS1 protein, CAT expression from the M-CAT RNA was significantly stimulated but transcription was not altered. The expression of NS-CAT RNA, which contains noncoding sequences of segment 8 (coding for the NS1 and NS2 proteins), was not altered by the NS1 protein. Site-directed mutagenesis showed that the sequence GGUAGAUA upstream of the initiation codon on segment 7 was required for stimulation.
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PMID:Influenza virus NS1 protein stimulates translation of the M1 protein. 750 95

Ro ribonucleoprotein particles (Ro RNPs) are evolutionarily conserved cytoplasmic complexes of unknown function. They are composed of several proteins and a small, RNA polymerase III-transcribed Ro or Y RNA. Abs directed against the protein moiety of Ro RNPs are often found in sera of patients suffering from certain autoimmune disorders. The association of one of the Ro proteins, a protein of 52 kDa (Ro52), with Ro RNPs is still questionable. In this study, we have used anti-Ro52 Abs isolated from autoimmune sera to locate the antigenic determinants of Ro52 and to analyze the correlation between regions of Ro52 recognized by these Abs and their ability to immunoprecipitate Ro RNPs. The results indicate that the autoimmune response against Ro52 is heterogeneous and that the exclusive recognition of certain epitopes does not result in immunoprecipitation of Ro RNPs.
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PMID:Epitope specificity determines the ability of anti-Ro52 autoantibodies to precipitate Ro ribonucleoprotein particles. 752 22

A novel gene transcribed by RNA polymerase (pol) III has been recently identified that produces an RNA component of a large cytoplasmic ribonucleoprotein complex (Kickhoefer, V. A., Searles, R. P., Kedersha, N. L., Garber, M. E., Johnson, D. L., and Rome, L. H. (1993) J. Biol. Chem. 268, 7868-7873). Since sequence analysis revealed that this gene contains promoter elements from two different classes of RNA pol III gene promoters, we examined the function of the 5'-flanking type-3 and internal type-2 sequences on transcription activity and the production of stable transcription complexes. We find that the vRNA gene contains a novel RNA pol III promoter, where both the external and internal sequences are essential for template activity and for the productive interaction of TFIIIC with the internal elements. Thus, the vRNA gene represents the first example of a template that requires both type-2 and type-3 promoter elements that appear to function synergistically in the formation of productive transcription complexes. We have further examined the function of the unique arrangement of an internal A box and two B box elements. We find that at least one B element is required for template activity. In the absence of the 5'-flanking sequence the presence of both B elements inhibits transcription and the binding of TFIIIC. The formation of active complexes is restored when either the B2 element is inactivated or the distance separating the two B elements is increased. Therefore, the B2 element appears to negatively regulate template activity in the absence of the upstream sequences. This unique RNA pol III promoter arrangement may provide a novel mechanism for the regulation of vRNA gene activity.
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PMID:The rat vault RNA gene contains a unique RNA polymerase III promoter composed of both external and internal elements that function synergistically. 752 87

The removal of introns from eukaryotic pre-mRNA occurs in a large ribonucleoprotein complex called the spliceosome. We have generated a monoclonal antibody (mAb 16H3) against four of the family of six SR proteins, known regulators of splice site selection and spliceosome assembly. In addition to the reactive SR proteins, SRp20, SRp40, SRp55, and SRp75, mAb 16H3 also binds approximately 20 distinct nuclear proteins in human, frog, and Drosophila extracts, whereas yeast do not detectably express the epitope. The antigens are shown to be nuclear, nonnucleolar, and concentrated at active sites of RNA polymerase II transcription which suggests their involvement in pre-mRNA processing. Indeed, most of the reactive proteins observed in nuclear extract are detected in spliceosomes (E and/or B complex) assembled in vitro, including the U1 70K component of the U1 small nuclear ribonucleoprotein particle and both subunits of U2AF. Interestingly, the 16H3 epitope was mapped to a 40-amino acid polypeptide composed almost exclusively of arginine alternating with glutamate and aspartate. All of the identified antigens, including the human homolog of yeast Prp22 (HRH1), contain a similar structural element characterized by arginine alternating with serine, glutamate, and/or aspartate. These results indicate that many more spliceosomal components contain such arginine-rich domains. Because it is conserved among metazoans, we propose that the "alternating arginine" domain recognized by mAb 16H3 may represent a common functional element of pre-mRNA splicing factors.
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PMID:A conserved epitope on a subset of SR proteins defines a larger family of Pre-mRNA splicing factors. 753 40

The La (SS-B) autoimmune antigen is an RNA-binding protein that is present in both the nucleus and cytoplasm of eukaryotic cells, where it is found associated with RNA polymerase III transcripts. We have investigated the capacity of anti-La monoclonal antibodies SW1, SW3, and SW5 to immunoprecipitate human La ribonucleoprotein particles. Distinct differences were observed for SW3 in comparison with SW1 and SW5. While SW1 and SW5 precipitated ribonucleoproteins containing pre-tRNA, pre-5S rRNA, hY RNAs, pre-U6 snRNA or the viral EBER1 and VA RNAs, SW3 precipitated only ribonucleoproteins containing VA RNAs or (the precursor of) 7-2 RNA. Mapping of the epitopes recognized by SW1, SW3, and SW5 revealed that all three monoclonal antibodies recognize an epitope within the domain of the protein formed by the ribonucleoprotein motif. Cross-competition studies suggested that the epitope recognized by SW1 and SW5 are identical but distinct from the epitope recognized by SW3. Further analyses of the recognition of La from other species by these monoclonal antibodies revealed that they all reacted with bovine La and were not reactive with La from rodents and Xenopus laevis. Replacement of a single amino acid in the human protein by its murine counterpart abolished recognition by SW1 and SW5, but had no effect on recognition by SW3. Taken together, our results indicate that SW1 and SW5 recognize the same epitope and that SW3 recognizes a distinct epitope, both of which are located in the RNA-binding domain of La, and that the accessibility of these epitopes is differentially influenced by the association of La with various RNA polymerase III transcripts.
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PMID:Anti-La monoclonal antibodies recognizing epitopes within the RNA-binding domain of the La protein show differential capacities to immunoprecipitate RNA-associated La protein. 755 14

The stable association of the N gene transcriptional antiterminator protein of bacteriophage lambda with transcribing RNA polymerase requires a nut site (boxA+boxB) in the nascent transcript and the Escherichia coli factors NusA, NusB, NusG, and ribosomal protein S10. We have used electrophoretic mobility shift assays to analyze the assembly of N protein, the E. coli factors, and RNA polymerase onto the nut site RNA in the absence of a DNA template. We show that N binds boxB RNA and that subsequent association of NusA with the N-nut site complex is facilitated by both boxA and boxB. In the presence of N, NusA, and RNA polymerase the nut site assembles ribonucleoprotein complexes containing NusB, NusG, and S10. The effects on assembly of mutations in boxA, boxB, NusA, and RNA polymerase define multiple weak protein-protein and protein-RNA interactions (e.g., NusB with NusG; NusA with boxB; NusA, NusB, and NusG with boxA) that contribute to the overall stability of the complex. Interaction of each component of the complex with two or more other components can explain the many observed cooperative binding associations in the DNA-independent assembly of a stable antitermination complex on RNA polymerase.
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PMID:A protein-RNA interaction network facilitates the template-independent cooperative assembly on RNA polymerase of a stable antitermination complex containing the lambda N protein. 759 Feb 57

The heat shock response of Chironomus polytene chromosomes was reexamined. The in vivo effects of heat shock on chromosomal [3H]uridine labeling, RNA polymerase II distribution and ribonucleoprotein (RNP) formation were investigated. One primary result is a clarification of the number and location of chromosomal sites strongly induced by treatment at 37 degrees C for 60 min. In total, seven major heat shock loci were identified by transcription autoradiography in Chironomus tentans: I-20A, II-16B, II-10C, II-4B, II-1C, III-12B, and IV-5C. Secondly, combining immunofluorescence with transcription autoradiography, I find RNA polymerase II occurring after heat shock at multiple chromosomal sites that were also active under normal conditions (20 degrees C). Furthermore, the results demonstrate conclusively that the presence of RNA polymerase II at heat shock and non-heat shock loci is generally correlated with [3H]uridine labeling during heat shock. These latter results extend and corroborate previous findings. Thirdly, the most striking result of this study was revealed in ultrathin sections of puffs by electron microscopy: I discerned a site-specific ultrastructural difference in putative RNP particles between heat shock versus non-heat shock loci. At least three of the seven induced major heat shock puffs (I-20A, III-12B, IV-5C) were observed to contain globular particles that were different, i.e. significantly larger, 250-1,000 A in diameter with a prominent 500-750 A class, than RNP particles of other loci under non-heat shock conditions. These large heat shock puff particles presumably represent nascent or newly synthesized heat shock RNA associated with protein(s) to form heat shock RNPs (hsRNPs). This finding suggests the possible involvement of novel RNPs (hsRNPs) in transcriptional regulation or heat shock RNA turnover and may stimulate further molecular investigations on this subject in both cell physiological and structural terms. I conclude that the locus-specific putative hsRNPs are an intrinsic property of greatly increased heat shock gene transcription.
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PMID:Transcription of heat shock gene loci versus non-heat shock loci in Chironomus polytene chromosomes: evidence for heat-induced formation of novel putative ribonucleoprotein particles (hsRNPs) in the major heat shock puffs. 762 2

8-Azido GTP (8-N3 GTP) was demonstrated to be polymerized into RNA by influenza virus-associated RNA polymerase at about one tenth the rate of GTP incorporation. The Km value for the azido analogue of GTP in primer-dependent RNA synthesis was 94 microM whereas Km for the natural substrate, GTP, was 6.7 microM. Upon exposure of a mixture of 8-N3 [alpha-32P]GTP and influenza virus ribonucleoprotein (RNP) complexes to ultraviolet light, the PB1 subunit of viral RNA polymerase was selectively radio-labeled. The photo-labeling of PB1 was competed strongly by GTP and to lesser extents by other nucleoside 5'-triphosphates. These results altogether support the prediction that the substrate-binding site (S site) of influenza RNA polymerase is located on the PB1 protein. In the presence of ApG primer, the 8-N3 GTP binding was reduced to about 40% level, suggesting that the GTP analogue can bind not only to the S site but also to the primer- and product-binding site (P site).
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PMID:Photoaffinity labeling of influenza virus RNA polymerase PB1 subunit with 8-azido GTP. 762 40

Most Saccharomyces cerevisiae strains carry in their cytoplasm 20 S RNA, a linear single-stranded RNA molecule of 2.5 kilobases in size. 20 S RNA copy number is greatly induced in stress conditions such as starvation, with up to 100,000 copies per cell. 20 S RNA has coding capacity for a protein of 91 kDa (p91) with sequences diagnostic of RNA-dependent RNA polymerases of (+) strand and double-stranded RNA viruses. We detected p91 in 20 S RNA-carrying strains with specific antisera. The amount of p91 in growing cells is higher than that of stationary cells and similar to the one in 20 S RNA-induced cells. Although 20 S RNA is not encapsidated into viral particles, p91 non-covalently forms a ribonucleoprotein complex with 20 S RNA. This suggests a role of p91 in the RNA to RNA synthesis processes required for 20 S RNA replication. Although the strain analyzed also harbors 23 S RNA, a closely related single-stranded RNA, 23 S RNA is not associated with p91 but with its putative RNA polymerase, p104. Similarly, 20 S RNA is not associated with p104 but with p91. These results suggest that 20 S RNA and 23 S RNA replicate independently using their respective cognate RNA polymerases.
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PMID:Yeast viral 20 S RNA is associated with its cognate RNA-dependent RNA polymerase. 765 26

Vaults are large cytoplasmic ribonucleoprotein particles with a sedimentation value of about 150 S. These particles contain a unique small RNA (vault RNA (vRNA)). We have determined the sequence of the RNA associated with vaults purified from both rat and bullfrog. The rat vRNA is 141 bases in length, whereas the bullfrog vRNA is present as two highly related species of 89 and 94 bases. Despite the differences in length the predicted secondary structures of the three vRNAs are clearly related. All of the vRNAs contain sequences related to the internal promoter elements necessary for transcription by RNA polymerase III. The gene for the rat vRNA was isolated and sequenced from a rat genomic library, and its transcription by RNA polymerase III was verified using an in vitro transcription assay. The rat vRNA gene was efficiently transcribed in vitro, producing a single transcript of about 140 bases. Unlike most RNA polymerase III genes, the rat vRNA is present as a single copy gene and has a distinct tissue-specific expression pattern.
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PMID:Vault ribonucleoprotein particles from rat and bullfrog contain a related small RNA that is transcribed by RNA polymerase III. 768 30


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