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)

Lovett, James S. (Purdue University, West Lafayette, Ind.). Chemical and physical characterization of "nuclear caps" isolated from Blastocladiella zoospores. J. Bacteriol. 85:1235-1246. 1963.-Electron micrographs of Blastocladiella zoospores have shown the nuclear cap to contain essentially all of the small (250 to 300 A) electron-dense particles of the cell. Preparations of clean, whole nuclear caps were isolated to study the composition of the intact organelles and their particulate contents. The cap is strongly basophilic, and is composed of 60% protein and 40% ribonucleic acid (RNA). It represents 18% of the dry weight, and contains 69% of the total RNA, of the spore. The amino acid composition of cap proteins is similar to the ribosomal protein of other organisms. The nuclear cap contents have been extracted and isolated by high-speed centrifugation. More than 95% of the material has a sedimentation coefficient of 83S in 0.005 m Mg. The 83S particles form aggregates at higher Mg concentrations and dissociate to yield 63S and 41S peaks at low Mg concentrations. Purified cap particles contain 37% protein and 63% RNA. The RNA has a nucleotide composition (in moles per cent) of 18.5% cytidylic, 26.2% adenylic, 31.8% guanylic, and 23.5% uridylic acid. The particles contain a latent ribonuclease, which can be activated by urea, and are susceptible to degradation by added pancreatic ribonuclease. The available evidence supports a concept of the zoospore nuclear cap as an unusual intracellular "packet" of ribosomes.
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PMID:CHEMICAL AND PHYSICAL CHARACTERIZATION OF "NUCLEAR CAPS" ISOLATED FROM BLASTOCLADIELLA ZOOSPORES. 1404 13

In Saccharomyces cerevisiae, the maturation of both pre-rRNA and pre-small nucleolar RNAs (pre-snoRNAs) involves common factors, thereby providing a potential mechanism for the coregulation of snoRNA and rRNA synthesis. In this study, we examined the global impact of the double-stranded-RNA-specific RNase Rnt1p, which is required for pre-rRNA processing, on the maturation of all known snoRNAs. In silico searches for Rnt1p cleavage signals, and genome-wide analysis of the Rnt1p-dependent expression profile, identified seven new Rnt1p substrates. Interestingly, two of the newly identified Rnt1p-dependent snoRNAs, snR39 and snR59, are located in the introns of the ribosomal protein genes RPL7A and RPL7B. In vitro and in vivo experiments indicated that snR39 is normally processed from the lariat of RPL7A, suggesting that the expressions of RPL7A and snR39 are linked. In contrast, snR59 is produced by a direct cleavage of the RPL7B pre-mRNA, indicating that a single pre-mRNA transcript cannot be spliced to produce a mature RPL7B mRNA and processed by Rnt1p to produce a mature snR59 simultaneously. The results presented here reveal a new role of yeast RNase III in the processing of intron-encoded snoRNAs that permits independent regulation of the host mRNA and its associated snoRNA.
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PMID:Genome-wide prediction and analysis of yeast RNase III-dependent snoRNA processing signals. 1579 87

In vivo studies have shown that the ribosomal large subunit protein L23a (Rpl23ab) in Saccharomyces cerevisiae is methylated at lysine residues. However, the gene encoding the methyltransferase responsible for the modification has not been identified. We show here that the yeast YPL208w gene product, a member of the SET domain family of methyltransferases, catalyzes the reaction, and we have now designated it Rkm1 (ribosomal lysine (K) methyltransferase 1). Yeast strains with deletion mutations in candidate SET domain-containing genes were in vivo labeled with S-adenosyl-l-[methyl-(3)H]methionine. [(3)H]Methyl radioactivity was determined after lysates were fractionated by SDS gel electrophoresis. When compared with the parent strain or other candidate deletion strains, a loss of a radiolabeled 15-kDa species was observed in the rkm1 (Deltaypl208w) knock-out strain. Treatment of wild-type cell extracts with RNase or proteinase K demonstrated that the methyl-accepting substrate is a protein. Cellular lysates from parent and knockout strains were fractionated using high salt sucrose gradients. Analysis of the gradient fractions by SDS gel electrophoresis demonstrated that the 15-kDa methyl-accepting substrate elutes with the large ribosomal subunit. In vitro methylation experiments using purified ribosomes confirmed that the methyl-accepting substrate is a ribosomal protein. Amino acid analysis of the in vivo labeled 15 kDa polypeptide showed that it contains epsilon-[(3)H]dimethyllysine residues. Mass spectrometry of tryptic peptides of the 15 kDa polypeptide identified it as Rpl23ab. Analysis of the intact masses of the large ribosomal subunit proteins by electrospray mass spectrometry confirmed that the substrate is Rpl23ab and that it is specifically dimethylated at two distinct sites by Rkm1. These results show that SET domain methyltransferases can be involved in translational roles as well as in the previously described transcriptional roles.
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PMID:A novel SET domain methyltransferase modifies ribosomal protein Rpl23ab in yeast. 1609 73

The synthetic polyribonucleotides adenylic acid (poly A), uridylic acid (poly U), cytidylic acid (poly C), and inosinic acid (poly I), whether single- or double-stranded (poly A:U, poly I:C), cannot replace mycobacterial ribonucleic acid (RNA) in the production of a high immune response in CF-1 mice against tuberculous disease. These conclusions are based on the results of several types of experiments. (i) Poly A and poly U, used either singly or in combination, did not increase the immunogenicity of mycobacterial RNA preparations whether emulsified in Freund's incomplete adjuvant (FIA) or not emulsified. (ii) Mycobacterial ribosomal protein, extracted with 2-chloroethanol, was not immunogenic; the addition of poly A:U to the protein did not produce an immune response and FIA did not affect these results. (iii) The RNA left after the protein was extracted was partially immunogenic when emulsified in FIA even though it was partially degraded. (iv) Mycobacterial RNA prepared with ethyl alcohol and partially degraded with ribonuclease had a significantly lower immunogenic activity, and the original higher immune response was not restored by the addition of poly A:U. (v) Mycobacterial RNA totally degraded by weak alkali was not immunogenic, the original immunogenic activity was not restored by the addition of poly A:U or poly I:C, and FIA again did not influence the results. These findings suggest that (i) protein, polypeptides, or other antigenic fragments, if present, are not the specific immunogens; and (ii) mycobacterial RNA is responsible for the high immunogenic activity of mycobacterial ribosomal and RNA preparations. In addition, since the double-stranded forms of these synthetic polynucleotides markedly potentiate the formation of circulating antibodies, these results also reemphasize the lack of correlation between conventional antibody formation and immunity against tuberculosis.
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PMID:Failure of synthetic polynucleotides to affect the immunogenicity of mycobacterial ribonucleic Acid and ribosomal protein preparations. 1655 31

Embryos from rice (Oryza sativa L. var. Bluebonnet) and wheat (Triticum aestivum L.) contain an aminoacyl-tRNA protein transferase which transfers arginine from arginyl-tRNA to the N terminus of a protein acceptor. The activity was measured in vitro in a reaction mixture containing embryo supernatant fraction, buffer, sulfhydryl reagent, and arginyl-tRNA. It was not dependent on the usual cofactors for ribosomal protein synthesis, nor was it sensitive to cycloheximide or puromycin. However, the activity was inhibited by ribonuclease. The enzyme was purified 33-fold from a crude homogenate of rice embryos. An apparent endogenous substrate from rice embryos was prepared free of transferase activity; however, the transferase was not purified sufficiently to show absolute dependence on the presence of this endogenous substrate.
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PMID:An arginyl-transfer ribonucleic Acid protein transferase from cereal embryos. 1665 90

The expression of ribosomal protein (rp) genes is regulated at multiple levels. In yeast, two genes are autoregulated by feedback effects of the protein on pre-mRNA splicing. Here, we have investigated whether similar mechanisms occur in eukaryotes with more complicated and highly regulated splicing patterns. Comparisons of the sequences of ribosomal protein S13 gene (RPS13) among mammals and birds revealed that intron 1 is more conserved than the other introns. Transfection of HEK 293 cells with a minigene-expressing ribosomal protein S13 showed that the presence of intron 1 reduced expression by a factor of four. Ribosomal protein S13 was found to inhibit excision of intron 1 from rpS13 pre-mRNA fragment in vitro. This protein was shown to be able to specifically bind the fragment and to confer protection against ribonuclease cleavage at sequences near the 5' and 3' splice sites. The results suggest that overproduction of rpS13 in mammalian cells interferes with splicing of its own pre-mRNA by a feedback mechanism.
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PMID:Human ribosomal protein S13 regulates expression of its own gene at the splicing step by a feedback mechanism. 1788 66

Drought is the largest constraint on rice production in Asia. Protein phosphorylation has been recognized as an important mechanism for environmental stress signaling. However, the differential expression of proteins and phosphoproteins induced by drought in rice is still largely unknown. In this paper, we report the identification of differentially expressed proteins and phosphoproteins induced by drought in rice using proteomic approaches. Three drought-responsive proteins were identified. Late embryogenesis abundant (LEA)-like protein and chloroplast Cu-Zn superoxide dismutase (SOD) were up-regulated by drought whereas Rieske Fe-S precursor protein was down-regulated. Ten drought-responsive phosphoproteins were identified: NAD-malate dehydrogenase, OSJNBa0084K20.14 protein, abscisic acid- and stress-inducible protein, ribosomal protein, drought-induced S-like ribonuclease, ethylene-inducible protein, guanine nucleotide-binding protein beta subunit-like protein, r40c1 protein, OSJNBb0039L24.13 protein and germin-like protein 1. Seven of these phosphoproteins have not previously been reported to be involved in rice drought stress. These results provide new insight into the regulatory mechanism of drought-induced proteins and implicate several previously unrecognized proteins in response to drought stress.
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PMID:Differential regulation of proteins and phosphoproteins in rice under drought stress. 1910 68

Bacteriophage T4 is the archetype of virulent phage. It has evolved very efficient strategies to subvert host functions to its benefit and to impose the expression of its genome. T4 utilizes a combination of host and phage-encoded RNases and factors to degrade its mRNAs in a stage-dependent manner. The host endonuclease RNase E is used throughout the phage development. The sequence-specific, T4-encoded RegB endoribonuclease functions in association with the ribosomal protein S1 to functionally inactivate early transcripts and expedite their degradation. T4 polynucleotide kinase plays a role in this process. Later, the viral factor Dmd protects middle and late mRNAs from degradation by the host RNase LS. T4 codes for a set of eight tRNAs and two small, stable RNA of unknown function that may contribute to phage virulence. Their maturation is assured by host enzymes, but one phage factor, Cef, is required for the biogenesis of some of them. The tRNA gene cluster also codes for a homing DNA endonuclease, SegB, responsible for spreading the tRNA genes to other T4-related phage.
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PMID:RNA processing and decay in bacteriophage T4. 1921 70

Angiogenin (ANG), originally identified as an angiogenic ribonuclease, has recently been shown to play a direct role in prostate cancer cell proliferation by mediating rRNA transcription. ANG is up-regulated in human prostate cancer and is the most significantly up-regulated gene in AKT-driven prostate intraepithelial neoplasia (PIN) in mice. Enhanced cell proliferation in the PIN lesions requires increased ribosome biogenesis, a multistep process involving an orchestrated production of ribosomal proteins and rRNA. AKT is known to enhance ribosomal protein production through the mammalian target of rapamycin pathway. However, it was unknown how rRNA is proportionally increased. Here, we report that ANG is essential for AKT-driven PIN formation and survival. We showed that up-regulation of ANG in the AKT-overexpressing mouse prostates is an early and lasting event. It occurs before PIN initiation and lasts beyond PIN is fully developed. Knocking down ANG expression by intraprostate injection of lentivirus-mediated ANG-specific small interfering RNA prevents AKT-induced PIN formation without affecting AKT expression and its signaling through the mammalian target of rapamycin pathway. Neomycin, an aminoglycoside that blocks nuclear translocation of ANG, and N65828, a small-molecule enzymatic inhibitor of the ribonucleolytic activity of ANG, both prevent AKT-induced PIN formation and reverse established PIN. They also decrease nucleolar organizer region, restore cell size, and normalize luminal architectures of the prostate despite continuous activation of AKT. All three types of the ANG inhibitor suppress rRNA transcription of the prostate luminal epithelial cells and inhibit AKT-induced PIN, indicating an essential role of ANG in AKT-mediated cell proliferation and survival.
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PMID:Angiogenin-stimulated rRNA transcription is essential for initiation and survival of AKT-induced prostate intraepithelial neoplasia. 1925 15

RNase Y is a novel endoribonuclease affecting global mRNA metabolism. We show that this nuclease affects the expression of the Bacillus subtilis infC-rpmI-rplT operon, encoding translation initiation factor IF3 and the ribosomal proteins L35 and L20. This operon is autoregulated by a complex L20-dependent transcription attenuation mechanism. L20 binds to a phylogenetically conserved domain on the 5' untranslated region of the infC mRNA which mimics the L20 binding sites on 23S rRNA. We have identified a second promoter (P1) upstream of the previously identified promoter (P2). The P1, but not the P2, readthrough transcript is stabilized in a strain depleted for RNase Y. However, under these conditions infC biosynthesis is repressed threefold. We show that the unprocessed P1 transcript is non-functional for IF3 translation but fully competent to express the co-transcribed ribosomal protein genes. RNase Y cleavage of the P1 transcript creates an entry site for the 5'-3' exonucleolytic activity of RNase J1 which degrades the infC mRNA when translation initiation efficiency is low. A second RNase Y cleavage is crucial for initiating degradation of the prematurely terminated infC leader RNAs, including the L20 operator complex, which permits efficient recycling of the L20 protein.
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PMID:RNase Y is responsible for uncoupling the expression of translation factor IF3 from that of the ribosomal proteins L35 and L20 in Bacillus subtilis. 2184 71


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