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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the relative importance of the 2',5'-phosphodiester bond of 2-5A in its binding to and activation of the 2-5A-dependent ribonuclease (RNase L, RNase F), a number of phosphodiester linkage isomers of 2-5A were prepared. These isomers were obtained either by lead ion-catalyzed polymerization of adenosine 5'-phosphorimidazolidate or by T4 polynucleotide kinase-catalyzed 5'-phosphorylation of adenylyl(3' leads to 5')adenylyl(3' leads to 5')adenosine followed by reaction of the corresponding phosphorimidazolidates with tri(n-butylammonium)pyrophosphate. The following 2-5A isomers thus were prepared: ppp5'A2'p5'A3'p5'A, ppp5'A3'p5'A2'p5'A, ppp5'A3'p5'A3'p5'A("3-5A"), ppp5'A2'p5'A3'p5'A2'p5'A,and ppp5'A3'p5'A2'p5'-A2'p5'A. The ability of these isomeric 2-5As to interact with the 2-5A-dependent endonuclease was ascertained by three different criteria: (i) ability to prevent the protein synthesis inhibitory effects of 2-5A, (ii) activity as an inhibitor of translation in encephalomyocarditis RNA-programmed L cell extracts, and (iii) ability to prevent binding of the radiolabeled probe, ppp5'A2'p5'A2'p5'A2'p5'A3'[32P]p5'Cp, to the endonuclease of L cell extracts. In certain experiments, degradation of oligonucleotide was minimized or eliminated by altering assay conditions, providing alternate phosphodiesterase substrates, or by using purified endoribonuclease of Ehrlich ascites cells. By all criteria, replacement of 2',5'-bond by a 3',5'-bond led to a substantial decrease in biological activity. Generally, replacement of just one 2',5'-phosphodiester bond with a 3',5'-linkage led to at least a one order of magnitude loss of activity. In accord with this trend, ppp5'A3'p5'A3'p5'A(3-5A) was greater than 10,000 less active than 2-5A in binding to the endonuclease or as an inhibitor of protein synthesis.
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PMID:Biological activities of phosphodiester linkage isomers of 2-5A. 663 Feb 22

The specificity of transcription of Euglena gracilis Z chloroplast DNA by chloroplast DNA-dependent RNA polymerase in a transcriptionally active chromosome (Hallick, R.B., Lipper, C., Richards, O.C., and Rutter, W.J. (1976) Biochemistry 15, 3039-3045) has been studied. RNA molecules are both initiated and elongated in vitro. The RNA transcripts have been characterized as to their size, nuclease sensitivity, 5'-terminal oligonucleotides, and coding locus on the chloroplast genome. RNA labeled in vitro at the 5' end with [gamma-32P]ATP was digested with RNase T1, RNase A, and S1 nuclease. The resulting 5'-gamma-32P-oligonucleotides were fractionated by gel electrophoresis. In each case, one or two discrete products were obtained, consistent with initiation in vitro only at defined loci. RNA labeled in vitro with [alpha-32P]ATP or CTP has been hybridized to Southern (Southern, E.M. (1975) J. Mol. Biol. 98, 503-517) transfers of restriction endonuclease fragments of chloroplast DNA. The most abundant in vitro transcripts hybridize to chloroplast DNA fragments coding for 23 S, 16 S, and 5 S rRNAs. Only the coding strands of the rRNA genes are transcribed. Non-rDNA sequences of chloroplast DNA are also selectively transcribed but at much lower levels. The transcriptionally active chromosome has proved to be an ideal biochemical preparation for the study of selective transcription of cell organelle DNA.
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PMID:Selective in vitro transcription of Euglena chloroplast ribosomal RNA genes by a transcriptionally active chromosome. 676 27

The hydrolysis of several tRNAs by an endonuclease extracted from the venom of Naja oxiana and specific for double-stranded, or at least highly ordered, regions has been studied under various experimental conditions. It is shown that the hydrolysis patterns of yeast tRNAPhe, tRNAVal and tRNAAsp in the isolated state are similar, most of the cuts occurring in the anticodon and acceptor stems. Ionic conditions are able to modify the hydrolysis pattern. The origin of these modifications is discussed. The protection against ribonuclease action, afforded to tRNAPhe, tRNAVal and tRNAAsp by the cognate aminoacyl-tRNA synthetase, is analyzed. It is shown that in all cases the anticodon stem is protected. The 3'-terminal region does not seem to be tightly engaged in the complex with the aminoacyl-tRNA synthetase. These results are discussed in the light of information on contact areas previously obtained by ultraviolet cross-linking techniques. The effects of the small ligands (ATP and amino acid) on the protection afforded to the tRNA by the cognate synthetase, have been studied. In the valine and aspartic acid systems, ATP induced a modification of the tRNA-enzyme complex leading to differences in the hydrolysis pattern of the 3'-accepting region. The effects of aminoacylation on the cleavage of tRNAPhe, tRNAVal and tRNAAsp were also studied. Whereas no modification of the cleavage map was observed in the aspartic system, aminoacylation resulted in slight but significant modifications of the hydrolysis pattern for tRNAPhe and tRNaVal in the 3'-terminal region.
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PMID:Comparison of the hydrolysis patterns of several tRNAs by cobra venom ribonuclease in different steps of the aminoacylation reaction. 691 54

A method for mapping all base-paired stems in both elongation and initiator tRNAs is described using double-stranded-specific ribonuclease V1 from the venom of the cobra Naja naja oxiana. 32p-end-labeled RNA is first partially digested with double-strand-specific V1 nuclease under near physiological conditions, and the resultant fragments are than electrophoretically fractionated by size in adjacent lanes of a polyacrylamide gel run in 90% formamide. After autoradiography, the base-paired nucleotides are definitively located by comparing V1 generated bands with fragments of known length produced by both Neurospora endonuclease and base-specific ribonucleases. Using the substrates yeast tRNAPhe an E, coli tRNAfMet of known three-dimensional structure, we find V1 nuclease to cleave entirely within every base-paired stem. Our studies also reveal that nuclease V1 will digest paired nucleotides not hydrogen-bonded by standard Watson-Crick base-pairing. In yeast tRNAPhe cleavage of both wobble base-pairs and nucleotides involved in tertiary base-base hydrogen bonding is demonstrated.
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PMID:Mapping tRNA structure in solution using double-strand-specific ribonuclease V1 from cobra venom. 703 4

Ribosomal proteins S1 when associated with the 30-S subunit does not interact with 16-S RNA but its binding is determined mostly by protein-protein interactions. These conclusions are based on the following data. 1. Ultraviolet irradiation (lambda = 254 nm) of the 30-S subunit does not result in the covalent cross-linking of S1 with 16-S RNA at irradiation doses up to 150 quanta/nucleotide, whereas the irradiation under the same conditions of S1 . polynucleotide complexes [S1 . poly(U), S1 . poly(A) and S1 . Q beta phage RNA] induces effective formation of polynucleotide-protein cross-links. 2. Mild treatment of 30-S subunits lacking S-1 with RNase A or with cobra venom endonuclease results in removal of 10--20% of the total nucleotide material but does not affect their sedimentation characteristics of their S1 binding capacity. 3. The association of S1 with S1-depleted 30-S subunits is insensitive to aurintricarboxylic acid, which is known as a strong inhibitor of complex formation between S1 and polynucleotides. 4. Mild trypsin treatment of S1-depleted 30-S subunits greatly reduces their S1 binding capacity.
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PMID:Ribosomal protein S1 associates with Escherichia coli ribosomal 30-S subunit by means of protein-protein interactions. 703 93

The acid deoxyribonuclease was isolated from Bombyx mori eggs and its physico-chemical properties were investigated. The enzyme purified 160-fold did not contain admixtures of phosphomono- and phosphodiesterases or ribonuclease. The molecular weight of the enzyme is 40 000 +/- 1000, isoelectric point lies at 6.5. The maximum activity is revealed at pH 5.2, 50 degrees. The DNAase is insignificantly activated by Mg2+ and is inhibited by Cu2+ and Zn2+. The enzyme preferentially hydrolyzes native DNA and is an endonuclease splitting DNA down to 5'-oligonucleotides.
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PMID:[Isolation, purification and properties of acid deoxyribonuclease from silkworm Bombyx mori eggs]. 707 75

A small RNA encoded within the nucleus of yeast and mammalian cells is an essential subunit of a mitochondrial RNA-processing endonuclease (RNase MRP) that generates primers for mitochondrial DNA (mtDNA) replication. We examined expression of MRP-RNA in specialized subtypes of mammalian striated muscles that differ markedly in respiratory activity and in muscles subjected to chronic stimulation via the motor nerve, a potent stimulus to mitochondrial biogenesis. MRP-RNA was more abundant in mitochondria-rich cardiac and slow-twitch skeletal muscles than in glycolytic fast-twitch skeletal muscles. Forced contractile activity resulting from nerve stimulation increased expression of MRP-RNA by 3.5-fold within the first day and by 14-fold within 14 days. Changes in abundance of MRP-RNA preceded but otherwise occurred in parallel to changes in specific activity of citrate synthase, a marker of mitochondrial proliferation shown previously to correlate with mtDNA copy number in this model. Another small RNA (U1) also was induced transiently (1-3 days) by nerve stimulation, but such changes were not sustained and were of less magnitude (< 4-fold) than changes in MRP-RNA. These findings are consistent with the hypothesis that MRP-RNA may have a regulatory function with respect to mtDNA replication and mitochondrial biogenesis.
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PMID:RNA subunit of mitochondrial RNA-processing enzyme is induced by contractile activity in striated muscle. 750 87

A small RNA encoded within the nucleus is an essential subunit of a RNA processing endonuclease (RNase MRP) hypothesized to generate primers for mitochondrial DNA replication from the heavy strand origin of replication. Controversy has arisen, however, concerning the authenticity of an intramitochondrial pool of MRP RNA, and has called into question the existence of pathways for nucleo-mitochondrial transport of nucleic acids in animal cells. In an effort to resolve this controversy, we combined ultrastructural in situ hybridization and biochemical techniques to assess the subcellular partitioning of MRP RNA. Cryosections of mouse cardiomyocytes were hybridized with biotin-labeled RNA probes complementary to different regions of MRP RNA and varying in length from 115 to 230 nucleotides, followed by immunogold labeling. In addition, we transfected mouse C2C12 myogenic cells with constructs bearing mutated forms of the mouse MRP RNA gene and compared the relative abundance of the resulting transcripts to that of control RNAs within whole cell and mitochondrial fractions. In the former analysis we observed preferential localization of MRP RNA to nucleoli and mitochondria in comparison to the nucleoplasm and cytoplasm. In the latter series of studies we observed that wild-type MRP RNA partitions to the mitochondrial fraction by comparison to other RNA transcripts that are localized to the extramitochondrial cytoplasmic space (28S rRNA) or to the nucleoplasm (U1 snRNA). Deletions within 5' or 3' regions of the MRP RNA gene produced transcripts that remain competent for mitochondrial targeting. In contrast, deletion of the midportion of the coding region (nt 118 to 175) of the MRP RNA gene resulted in transcripts that fail to partition to the mitochondrial fraction. We conclude that an authentic intramitochondrial pool of MRP RNA is present in these actively respiring cells, and that specific structural determinants within the MRP RNA molecule permit it to be partitioned to mitochondria.
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PMID:Subcellular partitioning of MRP RNA assessed by ultrastructural and biochemical analysis. 751 Jul 14

A study of the genetic variability of herpes simplex virus (HSV) type 1 from recurrent lesions and clinical reinfections was done using restriction endonuclease analysis and the RNase A mismatch cleavage method. Comparative genetic analyses of HSV-1 recurrent isolates from 1 patient and of HSV-1 isolates from different anatomic areas (vagina and lip) from another patient showed differences only in the glycoprotein B gene but not in the thymidine kinase gene even though the viruses had the same restriction endonuclease pattern. These results suggest the RNase A mismatch cleavage method is useful for epidemiologic studies of DNA viruses.
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PMID:Genetic analysis of herpes simplex virus type 1 isolates from recurrent lesions and clinical reinfections. 759 26

A ribonuclease H activity from human placenta has been separated by ion exchange chromatography from the major RNase HI enzyme. Additional chromatographic steps allowed further purification, more than 3,000 fold compared to the crude extract in which it represents about 15% of the total RNase H activity. The enzyme requires Mg2+ ions for its activity, is strongly inhibited by the addition of Mn2+ ions or other divalent transition metal ions, and exhibits a pH optimum between 8.5 and 9. It shows a strong sensitivity to the SH-blocking agent N-ethylmaleimide. It has a strict specificity for double-stranded RNA-DNA duplexes and exhibits neither single-stranded nor double-stranded RNase (or DNase) activities. Therefore, this enzyme displays the characteristics of class II RNase H and is now termed RNase HII. Renaturation gel assays and gel filtration experiments proved a monomeric structure for the active enzyme with a native molecular weight of about 33 kDa. The human RNase HII acts as an endonuclease and releases oligoribonucleotides with 3'-OH and 5'-phosphate ends. It is therefore a candidate for the RNase H-mediated effect of antisense oligodeoxynucleotides.
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PMID:Purification and characterization of human ribonuclease HII. 781 13


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