Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RNA Polymerase III”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1978

Structural relationships of low molecular weight viral RNAs synthesized by RNA polymerase III in nuclei from adenovirus 2-infected cells.

Previous studies have shown that endogenous class III RNA polymerase(s) in nuclei from adenovirus 2-infected cells synthesize virus-coded RNA species which are approximately 200 (V200), 156 (V156), and 140 (V140) nucleotides in length (Weinmann, R., Brendler, T. G., Raskas, H.J., and Roeder, R. G. (1976) Cell 7, 557-566). The V156 nuclear RNA is identical in sequence to the major virus-associated RNA (VA RNA1 or 5.5 S RNA) synthesized in intact cells (Ohe, K., and Weissman, S. M. (1971) J. Biol. Chem. 246, 6991-7009). The V140 RNA contains several components, one of which appears identical to a minor virus-associated RNA (VA RNAII) which is synthesized in infected cells (Mathews), M. B. (1975) Cell 6, 223-229). Thus transcription of the VA RNAI and VA RNAII genes in vitro accurately reflects the in vivo transcription of these genes. The V200 RNA contains all the nucleotide sequences found in V156 RNA plus an additional 38 to 40 nucleotides on the 3' terminus. Transcription of the gene encoding this RNA species terminates within a stretch of 6 deoxythymidylic acid residues which are located 38 nucleotides beyond the predicted termination site for VA RNAI and which are preceded by a GC-rich sequence of nucleotides. These data suggest either that the V200 RNA is a precursor to the VA RNAI or that the RNA polymerase III occasionally reads-through the presumptive VA RNAI gene termination signal and stops at a potentially stronger downstream termination site.

Adenoviridae↗
PubMed1977

RNA synthesized in vitro by calf thymus RNA polymerase III (C), as well as by E. coli RNA polymerase, is restricted to a subset of calf thymus DNA.

RNA synthesized in vitro from chromatin and DNA by calf thymus RNA polymerase III was evaluated by hybridization in vast DNA excess. The RNA contains RNA complementary to both moderately repeated and unique DNA sequences. Very highly repeated DNA is not transcribed. A greater portion of RNA transcribed from DNA by RNA polymerase III hybridizes to moderately repeated DNA than RNA transcribed by Escherichia coli RNA polymerase. In studies utilizing DNA absorbed to filters, RNA transcribed from chromatin in short incubations hybridized to a greater extent than RNA transcribed for longer times. Similar results were obtained with RNA transcribed from DNA by E. coli RNA polymerase. These results suggest: 1) RNA polymerase III may be responsible for the synthesis of RNA species in addition to tRNA and 5 S ribosomal RNA and a portion of this RNA is transcribed from unique DNA; and 2) in vitro there may be selectivity in the initiation of transcription by both E. coli RNA polymerase and calf thymus RNA polymerase III.

Animals↗
PubMed1978

Saccharomyces cerevisiae DNA-dependent RNA polymerase III: a zinc metalloenzyme.

Yeast nuclear RNA polymerase III was purified by batch adsorption to phosphocellulose, followed by ion-exchange chromatography on DEAE-Sephadex and affinity chromatography on DNA-Sepharose. Polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band which contained polymerase activity. The molecular weight estimated by sedimentation velocity centrifugation in a glycerol gradient was 380 000. Enzyme activity was inhibited 50% at 0.1 mM 1,10-phenanthroline and 100% of 1.0 mM, but was restored when 1,10-phenanthroline was removed by dialysis. Enzyme activity was not inhibited by 7,8-benzoquinoline, a nonchelating structural analogue of 1,10-phenanthroline. These results strongly suggest that inhibition of enzyme activity occurs by the formation of a reversible enzyme-zinc-phenanthroline ternary complex. The zinc content, measured by atomic absorption spectroscopy, was 2 g-atoms per mol of enzyme. Zinc was not removed from the enzyme by gel filtration on Sephadex G-25, by passage through Chelex-100 resin, or by dialysis against buffer containing 1,10-phenanthroline. Enzyme-bound zinc was removed by dialysis after denaturation of the enzyme with heat and sodium dodecyl sulfate. Enzyme-bound zinc did not exchange with free zinc. These results establish yeast nuclear RNA polymerase III as a zinc metalloenzyme.

Cell Nucleus↗
PubMed1977

Selective and accurate transcription of the Xenopus laevis 5S RNA genes in isolated chromatin by purified RNA polymerase III.

Chromatin isolated from immature oocytes was found to contain an endogenous RNA polymerase activity (RNA nucleotidyltransferase; nucleoside triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) that synthesizes predominately 5S RNA. However, the levels of total RNA synthesis and 5S RNA synthesis in chromatin were each stimulated 10- to 50-fold by an exogenous RNA polymerase III purified from X. laevis oocytes. The 5S genes in chromatin were transcribed by the exogenous enzyme in a highly selective (3000-fold above random) and predominately asymmetric fashion. A significant fraction of 5S RNA sequences were also found in a discrete transcript, approximately 5S in size. Total RNA synthesis was significantly stimulated when chromatin was transcribed by oocyte RNA polymerase I, murine RNA polymerase II, and low levels of Escherichia coli RNA polymerase. However, these enzymes did not significantly stimulate 5S RNA synthesis above the endogenous levels. Both homologous oocyte RNA polymerase I and III and E. coli RNA polymerase transcribed the 5S genes in deproteinized DNA to approximately the same extent (severalfold above random) and both the sense and anti-sense strands of the gene were transcribed. It appears, therefore, that both chromatin-associated components and a purified RNA polymerase III are necessary and sufficient for the selective and accurate transcription of the 5S RNA genes in vitro.

Animals↗
PubMed1979

Transcription of cloned Xenopus 5S RNA genes by X. laevis RNA polymerase III in reconstituted systems.

When incubated with a soluble extract from large oocytes of Xenopus laevis, recombinant DNA plasmids containing either X. laevis oocyte 5S DNA or X. borealis oocyte 5S DNA direct the synthesis of discrete 5S RNAs, which by size and sequence analysis are similar or identical to the corresponding 5S RNAs synthesized in vivo. Synthesis of the 5S RNAs is mediated by a soluble endogenous RNA polymerase III (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6), which presumably recognizes specific initiation and termination sites in the 5S genes. Optimal conditions for accurate synthesis and the kinetics of the reactions have been determined. A soluble postchromatin supernatant fraction has also been isolated from immature oocytes. Although devoid of a functional endogenous RNA polymerase III, this extract contains a component(s) that effects the accurate transcription of 5S genes (in a plasmid) by a purified RNA polymerase III.

Animals↗
PubMed1979

Faithful transcription of eukaryotic genes by RNA polymerase III in systems reconstituted with purified DNA templates.

The virus-associated (VA) RNAI gene in human adenovirus 2 DNA has been shown by Wu (Wu, G. J. (1978) Proc. Natl. Acad. Sci. U. S. A. 75, 2175--2179) to be transcribed by RNA polymerase III in a human KB cell-free extract. In the present report we have examined the fidelity of transcription of adenovirus 2 DNA and Xenopus oocyte 5 S DNA templates by RNA polymerase III in extracts derived from cultured human, murine, and amphibian kidney cells, Size and sequences analysis of the discrete transcripts synthesized in these homologous and heterologous systems indicate that they result from accurate transcription of the corresponding genes. The specific transcripts identified include both the adenovirus VA RNAI and VA RNAII, Xenopus 5 S RNA, and VA RNAI and 5 S RNA species with elongated 3' termini. The extracts derived from the various cell types differ in the ability to discriminate between the two VA RNA genes or between the heterogeneous 5 S RNA genes in the cloned DNA fragment. Wherease the human cell extracts transcribe the VA RNAI and VA RNAII genes of adenovirus at a relative frequency close to that observed in isolated nuclei, the amphibian cell extract appears to transcribe only the VA RNAI gene. The amphibian cell extract transcribes primarily that 5 S RNA gene (within 5 S DNA) which encodes the dominant oocyte 5 S RNA, whereas the human cell extract transcribes at least two distinct 5 S RNA genes. Additionally, it is shown that the VA RNAI and VA RNAII genes have separate promotor sites. The kinetics of the transcription reactions have been examined and conditions optimal for specific transcription have been established by examining the effects of salt, metal ion, and template concentrations on both total and specific RNA synthesis. It is also shown that components in the cell-free extract (from human cells) are active in directing the accurate transcription of adenovirus DNA by purified RNA polymerase III.

Adenoviruses, Human↗
PubMed2025

An RNA polymerase III tissue and tumor atlas uncovers context-specific activities linked to 3D epigenome regulatory mechanisms.

RNA polymerase III (Pol III) produces a plethora of small noncoding RNA species involved in diverse cellular processes, from transcription regulation and splicing to RNA stability, translation, and proteostasis. Though Pol III activity is broadly coupled with cellular demands for protein synthesis and growth, a more precise understanding of gene-level dynamics and context-specific expression patterns remains missing, in part due to challenges related to sequencing and mapping Pol III-derived small ncRNAs. Here, we establish a predictive multi-tissue map of human Pol III activity across 19 tissues and 23 primary cancer subtypes by comprehensively profiling the chromatin accessibility of canonical Pol III-transcribed gene classes. Our framework relies on the unique relationship between gene accessibility and Pol III transcription, inferring activity through uniform binary classification of ATAC-seq enrichment at Pol III-transcribed genes. By characterizing multi-context gene uniformity, we provide a definition of the core Pol III transcriptome, broadly active across specialized tissues, and catalog genes with varied levels of context specificity. Our genomic Pol III atlas uncovers variable levels of activity across tissues, including sharp contraction of the Pol III transcriptome in heart and brain tissues and frequent expansion across diverse cancers. We show that both tissue- and tumor-specific genes are significantly enriched within lamina-associated domains (LADs), and that aberrant expression of nuclear lamin proteins is sufficient to induce Pol III-emergent patterns at tumor-specific genes. Together, these findings link Pol III dynamics to subnuclear compartmentalization and provide a resource for better understanding Pol III expansion and small RNA biogenesis in cancer.

Journal Article↗
PubMed1979

DNA-dependent RNA polymerase III from Acanthamoeba castellanii: comparison of the catalytic properties of the trophozoite and cyst enzymes.

DNA-dependent RNA polymerase III was partially purified from trophozoites and immature cysts of the small soil ameba, Acanthamoeba castellanii. In contrast to the active modulation of the variety of transfer RNA species which are transcribed during encystment, no difference was found in the chromatographic or catalytic properties of the enzyme responsible for their transcription.

Amanitins↗
PubMed1979

A mutation which alters initiation of transcription by RNA polymerase III on the Ad5 chromosome.

Mutant dl 309 is a viable Ad5 deletion mutant. Whereas wild-type Ad5-infected HeLa cells contain two VAI RNA species [VAI(A) and VAI(G)] which differ by three nucleotides at their 5' ends, dl 309-infected HeLa cells contain VAI(G) but no VAI(A) RNA. Nucleotide sequence analysis indicates that dl 309 lacks two base pairs which precede the 5' end of VAI(A) by 22 nucleotides. Since the 5' ends of VAI RNAs are not processed, the 309 deletion serves to identify a portion of the sequence required for RNA polymerase III initiation. Since dl 309 grows as well as wild-type Ad5 in HeLa cells, the VAI(A) species is not essential for viral growth in these cells.

Adenoviruses, Human↗
PubMed1978

DNA-dependent RNA polymerase III from cauliflower. Characterization and template specificity.

Class III DNA-dependent RNA polymerase (EC 2.7.7.6) was highly purified from cauliflower (Brassica oleracea, var. bortytis) by using polyethyleneimine precipitation. The specific activity of the enzyme was comparable to that reported for mammalian enzymes. Glycerol gradient sedimentation analysis indicated that the sedimantation coefficient (23 S) was slightly higher than that of enzyme II from cauliflower. The class III enzyme was inhibited by alpha-amanitin at high concentrations (50% inhibition at 200 microgram/ml). The Km value for nucleoside triphosphate was determined. Template specificities for single synthetic polymers showed that the enzyme read pyrimidine homopolymers as templates and preferred poly(dT) to poly(dC). The enzyme transcribed both strands of homopolymer pairs of poly(dI). poly(dC) and poly(dA).poly(dT). The synthetic polyribonucleotides were not effectively read. Competition experiments with these synthetic polymers indicated that the enzyme had different binding specificities which were not the same as their template specificities. The different binding affinities and template specificites for synthetic templates of the three classes of enzyme suggest that the enzyme can discriminate among different template sequences.

Amanitins↗
PubMed2026

Defective RNA Polymerase III sensing of mitochondrial DNA in pulmonary epithelial cells impairs type I IFN immunity to SARS-CoV-2.

The clinical spectrum of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection ranges from asymptomatic cases to critical COVID-19 pneumonia. To investigate the role of host genetics in susceptibility to critical COVID-19 and identify pathophysiological mechanisms and pathways, we analyzed whole-exome and whole-genome sequencing data from the COVID Human Genetic Effort. We identified 10 rare, monoallelic predicted loss-of-function variants in 18 patients in POLR3A and POLR3C encoding two subunits of RNA polymerase III (POL III), a nuclear multisubunit enzyme, which has been implicated in cytosolic DNA sensing. These variants were deleterious for expression of full-length POLR3A and POLR3C proteins. We demonstrate that human pulmonary A549-hACE2 cells with reduced POLR3A or POLR3C expression exhibit impaired type I IFN responses to transfected mitochondrial DNA (mtDNA) or SARS-CoV-2 infection, together with increased viral replication. Mechanistically, we show that SARS-CoV-2 induces cellular mtDNA release via oligomerization of the mitochondrial voltage-dependent anion channel under virus-induced oxidative stress, enabling POL III-mtDNA interaction. These findings establish POL III as a sensor of endogenous mtDNA released during viral infection and indicate that autosomal dominant POL III haploinsufficiency may predispose individuals to critical COVID-19.

Humans↗
PubMed2025

Should I stay or should I go: TFIIIC as assembly factor and barrier in RNA polymerase III transcription.

Critical for the regulation of eukaryotic gene transcription is the assembly and interplay of general transcription factors (GTFs) with RNA polymerases (RNAPs), leading to the formation of pre-initiation complexes (PICs) as a rate-limiting step in transcription activation. Compared with RNAPII PIC assembly involving many GTFs, activators, and co-activators, RNAPIII PIC assembly is less complex, involving mainly the four GTFs TFIIIA, TFIIIB, TFIIIC, and snRNA activating protein complex with only a few additional factors. The RNAPIII-specific GTF TFIIIC is present in type I and II promoters. One prominent area of investigation has been the dynamic interaction between TFIIIC and its promoter elements, the varying affinities of TFIIIC toward these elements, and the flexible linker within TFIIIC. Additionally, evidence suggests that TFIIIC may play a dual role, acting as an assembly factor that positions TFIIIB during PIC formation and as a barrier during RNAPIII-mediated transcription. By summarizing recent structural, biochemical, and genomic data, this review explores the mechanisms by which RNAPIII-specific GTFs, with a focus on TFIIIC, dynamically regulate RNAPIII transcription.

RNA Polymerase III↗
PubMed1979

Delimitation of a promoter for RNA polymerase III by means of a functional test.

A Xenopus laevis DNA segment containing the structural gene for tRNA1Met and 22 base pairs at the 5' side of the gene is active in tRNA production. The DNA segment was ligated to sea urchin histone DNA and was also inserted into plasmid pCR1. Both recombinant DNAs were shown to produce mature tRNA1Met at a high rate when injected into centrifuged Xenopus oocytes.

Animals↗
PubMed1979

RNA polymerase III transcriptional units are interspersed among human non-alpha-globin genes.

Cloned human DNA fragments containing globin genes are transcribed in vitro to form discrete RNA species. One transcription unit is located approximately 1500 base pairs upstream from the G-gamma-globin gene. This transcript is partially homologous to a polymerase III template located approximately 1000 base pairs upstream from the delta-globin gene and to DNA located a short distance downstream from the beta-globin gene.

Cloning, Molecular↗
PubMed1978

A nuclear extract of Xenopus laevis oocytes that accurately transcribes 5S RNA genes.

Xenopus 5S RNA genes in recombinant form with the plasmid pMB9 are transcribed accurately when added to a supernatant fraction obtained from disrupted nuclei of Xenopus laevis oocytes. After an initial 30 min lag period, the rate of synthesis of 5S RNA is constant for at least an hour and synthesis is still detected after 18 hr. As much as 40% of the total RNA synthesized from the recombinant DNA used in these experiments can be 5S RNA. The coding strand of the 5S RNA genes is transcribed at a rate 10 to 15 times greater than the noncoding strand. Plasmid and spacer DNA, however, are also transcribed. What fraction of total RNA synthesized is 5S RNA is strongly affected by DNA concentration, ionic strength and MgCl2 concentration. Inhibition of transcription by intermediate concentrations of alpha-amanitin demonstrates that RNA polymerase III transcribes at least 90% of all RNA synthesized. Adenovirus 2 DNA is also transcribed in the nuclear supernatant by RNA polymerase III. Approximately 15% of the total RNA synthesized migrates in an acrylamide gel as a band of 5.5S RNA and has been identified as virus-associated RNA1 by its oligonucleotide fingerprint.

Animals↗
PubMed1979

Sigma subunit of Escherichia coli RNA polymerase affects the function of lambda N gene.

A new class of Escherichia coli mutants, referred to as grn, has been isolated by localized mutagenesis. These mutations affect the sigma subunit of DNA-dependent RNA polymerase (ribonucleoside 5'-triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) by abolishing the expression of the lambda N gene, and they are closely lniked to dnaG in the order dnaG-grn-uxaA. Detailed study of one such mutant, grn1, yielded the following results: (i) grn1 is a single mutation and the mutant cell shows cold-sensitivity in growth; (ii) the Grn phenotype of the mutant can easily be suppressed by secondary mutations in the beta subunit gene of RNA polymerase; (iii) purified holoenzyme of RNA polymerase isolated from the mutant showed an altered salt-dependency in vitro, and the mixed reconstitution of the mutant with the wild-type subunits showed that the sigma subunit of the grn1 mutant is altered; (iv) lambda phage mutants (lambda grg), which overcome the grn mutation, can be classified into two groups, the "nin-deletion" and the "N-mutant" groups (both of these are also able to grow on the previously described groN mutant of Georgopoulos and nusAB of Friedman); (iv) the mutant polymerase transcribed 12S as well as 7S RNA from lambda DNA in the presence of the rho factor in vitro. These results indicate that the grn mutation alters the sigma subunit of RNA polymerase and that the sigma subunit participates in activating the N-mediated antitermination mode of lambda phage transcription.

Bacteriophage lambda↗