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:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is generally assumed that the machinery that transcribes genes is composed entirely of polypeptides. However, in vitro transcription by silkworm RNA polymerase III requires a transcription factor that is not a polypeptide. This component, TFIIIR, is distinct from the previously identified transcription components: RNA polymerase III, and the accessory factors TFIIIA, TFIIIB, TFIIIC, and TFIIID. The newly discovered TFIIIR is a macromolecule that appears to be composed of RNA. It is resistant to heat, detergent, phenol, protease, and deoxyribonuclease, but it is sensitive to alkali and ribonuclease.
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PMID:A class III transcription factor composed of RNA. 170 25

Immature Xenopus laevis oocytes contain large quantities of a 7S ribonucleoprotein particle containing transcription factor IIIA (TFIIIA) and 5S RNA in a 1:1 molar ratio. We have reconstituted RNPs containing 5S RNA and either intact TFIIIA or proteolytic fragments that represent progressive C-terminal deletions of the protein. A partial trypsin digestion fragment encompassing the amino terminal seven zinc fingers of TFIIIA rebinds 5S RNA with nearly the same affinity as intact TFIIIA. We have compared the RNase protection patterns resulting from binding of intact and deleted forms of TFIIIA. RNAse protection assays using cobra venom nuclease were performed on complexes reconstituted with 5' and 3' end-labeled 5S RNA. Similar experiments with 3' end-labeled 5S RNA were performed with nuclease alpha-sarcin. With both nucleases, nucleotides in helix V of 5S RNA show more complete protection from nuclease cleavage when the RNA is bound to intact TFIIIA than when it is bound to a 20 kDa tryptic fragment of TFIIIA lacking the C-terminal portion of the protein. These results suggest that fingers 8 and 9 of TFIIIA interact with the distal portion of helix V in the 5S RNA.
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PMID:The carboxyterminal zinc fingers of TFIIIA interact with the tip of helix V of 5S RNA in the 7S ribonucleoprotein particle. 182 69

Transcription of the major oocyte 5S RNA gene (o) and pseudogene (psi) of Xenopus laevis yields different RNAs with three different homologous systems: oocyte microinjection, whole oocyte extract, and fractionated TFIIIA + TFIIIB + TFIIIC components. Those peculiar results are caused by a 3' RNA exonuclease activity, which is inhibited in the oocyte extract, that rapidly degrades the pseudogene 5S RNA but does not degrade as readily the chimeric RNA transcripts generated by HindIII-truncated 5S RNA pseudogenes. The same, or a similar, RNase activity processes the 130- and the 142-base-long transcripts of the major oocyte 5S RNA gene into mature 120-base-long 5S RNA. We performed site-specific mutagenesis on the somatic 5S RNA gene and changed specific nucleotides on the somatic 5S RNA. These studies indicated that the structure that confers stability to the 5S RNA in vivo and in vitro is the 9-bp helix formed in 5S RNA, but not in psi 5S RNA, by the complementary 5' and 3' ends of the molecule.
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PMID:A 3' exonuclease activity degrades the pseudogene 5S RNA transcript and processes the major oocyte 5S RNA transcript in Xenopus oocytes. 277 74

In small oocytes of Xenopus species, two sets of 5S RNA genes, oocyte-type and somatic-type, are fully activated. The 5S RNA transcripts are temporarily stored, half in association with TFIIIA to form a 7S particle, the other half in association with tRNA and two proteins (p48 and p43) to form a 42S particle. It has been established previously that TFIIIA binds to the internal control region of 5S RNA genes and promotes their transcription. Here we show that protein can be translocated from the 42S particles to 5S RNA genes, but only after treatment of the particles with ribonuclease. Nevertheless, once transferred, stable protein-DNA complexes are formed and DNase-protection experiments show that binding is specific to the gene promoter, covering exactly the same sequence as TFIIIA. The DNA-binding protein is identified as p48 which, after isolation by ion-exchange chromatography, will bind to 5S RNA genes in the absence of ribonuclease.
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PMID:An alternative protein factor which binds the internal promoter of Xenopus 5S ribosomal RNA genes. 368 70

The 5S RNA complexed in the 7S particle of immature Xenopus laevis oocytes was 32P labeled at its 3' end and then subjected in situ to partial digestion using ribonucleases T1, T2, A, and V1 in order to study the conformation of the complexed RNA and its interaction with the transcription factor A (TFIIIA). Digested samples were gel purified to retrieve 5S RNA that was still complexed with the transcription factor protein, and the cleavages in these RNAs were analyzed on sequencing gels. The RNA associated with the 7S particle is very susceptible to ribonuclease activity despite the presence of the protein. Also, the 5S RNA in the 7S particle is in a different conformation from renatured Xenopus laevis (Xlo) 5S RNA and appears to have less secondary structure predominantly in the stem that includes helices IV and V. A species of native Xlo 5S RNA which was isolated from 7S particle preparations under nondenaturing conditions revealed a conformation that was more similar to the 5S RNA in the 7S particle than to renatured 5S RNA. Comparison of data from partial ribonuclease digestions performed on renatured 5S RNA, on the native 5S RNA, and on the complexed 5S RNA allowed us to approximate sites of protein-induced structural change in the complexed 5S RNA, which may signal protein interaction domains. These sites include the 5' side of helices III and V. In another approach to the study of 5S RNA-TFIIIA interactions, we have observed that incubation of 32P-labeled Xlo 5S RNA with 7S particles results in the incorporation of labeled RNA into 7S particles.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:5S RNA structure and interaction with transcription factor A. 2. Ribonuclease probe of the 7S particle from Xenopus laevis immature oocytes and RNA exchange properties of the 7S particle. 608 16

Zinc fingers 4 to 7 of Xenopus transcription factor IIIA (TFIIIA) represent the minimal polypeptide necessary for high-affinity binding to 5 S RNA. Mutations covering the entire 5 S RNA structure have been compared for their effects on the binding affinity of full-length TFIIIA and a polypeptide consisting of fingers 4 to 7 of TFIIIA (zf4-7). In addition, ribonuclease footprinting was used to compare the binding sites of TFIIIA and zf4-7 on 5 S RNA. The consistency between the data obtained from these two approaches provided a clear indication that zinc fingers 4 to 7 of TFIIIA bind to a central core region on the 5 S RNA molecule consisting of loop B/helix II/loop A/helix V/region E. This information was used to design a truncated 75-nucleotide-long RNA molecule that retains high affinity for zf4-7. Therefore, we conclude that the specific interaction of TFIIIA with 5 S RNA can be represented by a complex formed between a four zinc finger polypeptide and a truncated 5 S RNA molecule.
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PMID:Interaction of the RNA binding fingers of Xenopus transcription factor IIIA with specific regions of 5 S ribosomal RNA. 773 Oct 45

To better understand the mechanisms that regulate stable RNA synthesis, we have analyzed the RNA polymerase I and III transcriptional activities of extracts isolated from cells propagated under a variety of conditions. Under balanced growth conditions the levels of both RNA polymerase I- and III-specific transcription increased proportionally with growth rate. Upon nutritional starvation, RNA polymerase I transcription rapidly declined, followed by 5 S rDNA and eventually tDNA transcription. Transcriptional activities in extracts were restored when the nongrowing cultures were resuspended in fresh medium, although growth did not resume. The differential expression of 5 S rDNA and tDNA genes in extracts prepared from cells subjected to partial starvation was traced to a 5 S rDNA-specific inhibitor and not to a defect in any RNA polymerase III transcription factor. Characterization of this inhibitor indicated that it was not 5 S rRNA. It was sensitive to phenol extraction and resistant to RNase, and its target did not appear to be transcription factor IIIA. Not all treatments that slowed or stopped growth down-regulated the stable RNA transcription apparatus. Cells that have been subjected to either energy starvation or cycloheximide treatment still retain the ability to synthesize stable RNA in vitro, suggesting the presence of alternative regulatory mechanisms.
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PMID:Regulation of the RNA polymerase I and III transcription systems in response to growth conditions. 870 32

The Wilms tumor suppressor gene WT1 is implicated in the ontogeny of genito-urinary abnormalities, including Denys-Drash syndrome and Wilms tumor of the kidney. WT1 encodes Kruppel-type zinc finger proteins that can regulate the expression of several growth-related genes, apparently by binding to specific DNA sites located within 5' untranslated leader regions as well as 5' promoter sequences. Both WT1 and a closely related early growth response factor, EGR1, can bind the same DNA sequences from the mouse gene encoding insulin-like growth factor 2 (Igf-2). We report that WT1, but not EGR1, can bind specific Igf-2 exonic RNA sequences, and that the zinc fingers are required for this interaction. WT1 zinc finger 1, which is not represented in EGR1, plays a more significant role in RNA binding than zinc finger 4, which does have a counterpart in EGR1. Furthermore, the normal subnuclear localization of WT1 proteins is shown to be RNase, but not DNase, sensitive. Therefore, WT1 might, like the Kruppel-type zinc finger protein TFIIIA, regulate gene expression by both transcriptional and posttranscriptional mechanisms.
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PMID:RNA binding by the Wilms tumor suppressor zinc finger proteins. 875 14

Rat Zn-15 is a transcription factor activating GH gene expression by synergistic interactions with Pit-1, named for 15 DNA-binding zinc fingers, including fingers IX, X, and XI that are responsible for GH promoter binding. In this study, a mouse cDNA for Zn-15 was characterized. The predicted 2192-amino acid mouse protein is 89% identical to rat (r) Zn-15 overall, and is 97% similar in the C-terminal domain necessary for binding the GH promoter. However, the mouse cDNA encodes 16 zinc fingers, and sequences of rZn-15 pituitary cDNAs were the same as the mouse (m) Zn-16; the rat sequence in GenBank has a one nucleotide offset of a 17-bp segment in the finger V region. The mouse and corrected rat sequences contain four tandemly repeated fingers in the N-terminus, each separated by seven amino acids, typical of zinc finger proteins of the transcription factor IIIA-type. Analysis of mZn-16 expression by RT-PCR showed that the mRNA is, produced at similar levels in normal and GH-deficient Ames dwarf (Prop-1 <df-/->) mouse pituitaries at postnatal day 1. Mouse Zn-16 mRNA also was detected by ribonuclease protection assay in the pre-somatotrophic mouse cell line GHFT1-5. The Zn-16 protein is bipartite in that the N-terminal half displays tandem spacing typical of most zinc finger proteins, while the C-terminal portion contains long linkers between fingers that cooperatively bind to a DNA response element. Expression in early postnatal pituitary and in pre-somatotrophic cells suggests that Zn-16 could play a role in pituitary development prior to somatotroph differentiation.
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PMID:Mouse growth hormone transcription factor Zn-16: unique bipartite structure containing tandemly repeated zinc finger domains not reported in rat Zn-15. 1068 55

Xenopus transcription factor IIIA (TFIIIA) binds 5S rRNA and the 5S rRNA gene, these interactions being mediated by nine zinc fingers. To determine the contribution of each finger to the binding to 5S rRNA we prepared a series of peptides containing different numbers of zinc fingers and analyzed their interactions with RNA. The topography of these complexes was analyzed with the specific RNase and hydroxyl radical footprinting methods. Our results show the direct contribution of each zinc finger (ZF) peptide to the specific recognition of 5S rRNA. These data clearly suggest that total binding of TFIIIA with 5S rRNA is the sum of the specific interactions of the individual zinc fingers with RNA and that they have an additive character.
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PMID:Additivity of interactions of zinc finger motifs in specific recognition of RNA. 1192 95


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