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)

The sequence of 129 nucleotides next to the poly(A) tail of encephalomyocarditis virus RNA has been determined by rapid gel sequencing of cDNA synthesized with DNA polymerase I or reverse transcriptase and a phasing primer, [5'-32P]p(dT)8dC. The sequence is in accord with (a) the pyrimidine tracts which were mapped in blocks along the cDNA, (B) the sequences of seven characteristic T1 RNase oligonucleotides in the RNA transcribed from the cDNA with RNA polymerase, and (c) a limited amount of sequence deduced by partial spleen phosphodiesterase digestion and depurination of endonuclease IV oligonucleotides. The 3' end shows little secondary structure on its own. Ten nonsense codons block all three reading frames such that at least 26 nucleotides do not code for protein. The possible function of a homology A-A-U-A-A-A with other polyadenylated RNAs is discussed.
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PMID:Sequence of 129 nucleotides at the 3'-terminus of encephalomyocarditis virus RNA. 7 85

The properties of the enzyme ribonuclease N were investigated. By comparing the distribution in the cell of RNase N with the bonafide intracellular beta-galactosidase, and the periplasmic alkaline phosphatase enzymes, we showed that RNase N is an intracellular enzyme. Since previous studies suggested that it is an endoribonuclease, it was compared to RNase III, the only other known intracellular endoribonuclease in Escherichia coli. Using homopolymers and co-polymers we found that, while RNase III could digest double-stranded RNA only, RNase N digested single-stranded and double-stranded RNA with similar efficiency. Furthermore, all RNAs used, natural as well as synthetic, were substrates for the enzyme. Using 5 S rRNA as a substrate it was confirmed that the enzyme is an endonuclease. The final products of the reaction of this enzyme are 5'-mononucleotides. The molecular weight of the enzyme is about 120,000 and it seems to contain two subunits which are similar in size. These properties thus differentiate this enzyme from all other known ribonucleases in E. coli.
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PMID:Characterization of an endoribonuclease, RNase N, from Escherichia coli. 9

The infectivity of replicative form RNA (RF-RNA) isolated from poliovirus-infected HeLa cells is completely resistant to the action of T-1 RNase but decreases after exposure to RNase A in the presence of 0.3 M NaCl. Under these conditions neither enzyme produces single-stranded nicks in RF-RNA. Three endonuclease-free exonuleases (RNase II, polynucleotide phosphorylase and spleen phosphodiesterase) rapidly destroy the infectivity of single-stranded RNA, but do not alter the infectivity of RF-RNA. It is concluded that RF-RNA does not contain single-stranded ends essential for infectivity. Indirect evidence suggests that all or most of the poly A region at the 3' end of the plus strand of infectious RF-RNA is base-paired to a poly U region at the 5 end of the minus strand.
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PMID:Poliovirus-induced infectious double-stranded RNA: Effect of RNA-degrading enzymes. 16 28

Limited T1 RNase digestion of subfragments of the SV40 DNA restriction endonuclease fragment EcoRII-G were prepared and analyzed. The fragments were separately labeled with 32P at their 5' terminus and the terminal sequences analyzed with limited snake venom diesterase digestion. The data permitted us to deduce the nucleotide sequence for EcoRII-G. The sequence contains a stretch of 17 A-T base pairs preceding the DNA complementary to the 5' end of "early" message RNA, a stretch of 27 bases with a perfect 2-fold rotational symmetry near the origin of DNA replication and a perfect tandem repeat of 21 nucleotides.
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PMID:Nucleotide sequence of a fragment of SV40 DNA that contains the origin of DNA replication and specifies the 5' ends of "early" and "late" viral RNA. III. Construction of the total sequence of EcoRII-G fragment of SV40 DNA. 18 10

Cytoplasmic mRNA isolated from cells infected with SV40 was isolated by passage over oligo(dT)-cellulose columns. This RNA was annealed to SV40 DNA fragments produced by cleavage with EcoRII endonuclease. The RNA resistant to RNase digestion was analyzed by digestion with ribonucleases and oligonucleotide mapping. The results were compared with oligonucleotides from in vitro transcripts of the fragments and with whole genome SV40 cRNA which had been fractionated by hybridization to the fragments. The 5' ends of "early" and the large "late" SV40 mRNA, transcribed from opposite DNA strands, overlap for a region of 60 to 100 nucleotides. The region of overlap includes a portion of the segment of DNA containing the origin of DNA replication.
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PMID:Nucleotide sequence of a fragment of SV40 DNA that contains the origin of DNA replication and specifies the 5' ends of "early" and "late" viral RNA. IV. Localization of the SV40 DNA complementary to the 5' ends of viral mRNA. 18 11

Simian virus 40 (SV40) DNA I was transcribed with Escherichia coli RNA polymerase in the presence of gamma-32P-labeled ribonucleoside triphosphates in order to investigate the specificity of initiation of in vitro transcription. ATP and GTP served as predominant initiating nucleotides, the former being incorporated about twice as much as the latter. Cleavage of [gamma-32P]ATP-labeled SV40 complementary RNA (cRNA) with T1 RNase followed by homochromatographic analysis of the resultant 5' initiation fragments revealed the presence of four specific initiation fragments 6 to 9 nucleotides in length, designated AI, AII, AIIIa, and AIIIb. By means of hybridization of [gamma-32P]ATP-labeled SV40 cRNA to DNA from specific adenovirus 2-SV40 hybrids and specific restriction endonuclease fragments of SV40 DNA before chromatographic analysis, it was possible to identify and determine approximate localizations of five [gamma-32P]ATP initiation sites on the SV40 genome: one in Hin-G close to the Hin-G-B junction, giving rise to the AII fragment, two in the overalpping fragment Hin-A-Hae-A,giving rise to AI and AIII fragments, and two in the fragment Hin-A-Hae-E, also giving rise to AI and AIII fragments. All five sites either fall within or lie near regions of the genome that are cleaved by S1 nuclease and subject to partial alkaline denaturation. These five sites lie on the minus strand of SV40 DNA and initiate RNAs that are copied in a leftward direction. Cleavage of [gamma-32P]GTP-labeled cRNA with pancreatic RNase liberated three major 5' initiation fragments of short length, GI, GII, and GIII, suggesting the presence of three principal GTP initiation sites.
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PMID:Specificity of initiation of transcription of simian virus 40 DNA I by Escherichia coli RNA polymerase: identification and localization of five sites for initiation with [gamma-32P]ATP. 19 61

During an electron-microscopic survey with the aim of identifying the parvovirus MVM transcription template, we observed previously unidentified structures of MVM DNA in lysates of virus-infected cells. These included double-stranded "lasso"-like structures and relaxed circles. Both structures were of unit length MVM DNA, indicating that they were not intermediates formed during replication; they each represented about 5% of the total nuclear MVM DNA. The proportion of these structures was unchanged after digestion with sodium dodecyl sulfate/Pronase and RNase and after mild denaturation treatment. Cleavage of the "lasso" structures with EcoRI restriction endonuclease indicated that the "noose" part of the "lasso" structure is located on the 5' side of the genomic single-stranded MVM DNA. A model is presented for the molecular nature of the circularization process of MVM DNA in which the "lasso" structures are identified as intermediates during circle formation. This model proposes a mechanism for circularization of linear DNAs.
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PMID:Mechanism for circularization of linear DNAs: circular parvovirus MVM DNA is formed by a "noose" sliding in a "lasso"-like DNA structure. 29 64

The chemically synthesized gene for Escherichia coli tyrosine suppressor tRNA has been joined to both plasmid (ColE1 ampr) and bacteriophage (Charon 3A) vector chromosomes after the latter had been digested with the restriction endonuclease EcoRI. Suppression of both bacterial (trpA, his, lacZ) and bacteriophage lambda amber mutations (Aam32, Bam1) has been demonstrated after transformation of E. coli with the recombinant DNA molecules carrying the synthetic suppressor tRNA gene. The cloned synthetic gene has been reisolated from the vector chromosomes after digestion of the latter with EcoRI restriction endonuclease and characterized in regard to its size and its ability to serve as a source of suppressor activity in further transformation experiments. This synthetic gene has also been shown to suppress bacterial amber mutations after it had been incorporated into the E. coli chromosome as part of a lambda prophage. Transcription, in vitro, of the cloned synthetic suppressor gene gave a product which, on treatment with a crude E. coli extract, afforded the tyrosine suppressor tRNA precursor. The latter was characterized by two-dimensional fingerprinting after digestion with T1-RNase. Exposure of the in vitro transcript to RNase P Selectively released the 41-nucleotide-long fragment characteristic of the 5'-end of the tRNA precursor. Thus, the nucleotide sequence of the cloned gene is accurate and its expression is controlled by its promoter.
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PMID:Total synthesis of a tyrosine suppressor tRNA gene. XVIII. Biological activity and transcription, in vitro, of the cloned gene. 37 20

Approximately 15% of the polyadenylic acid-containing cytoplasmic RNA labeled from 5 to 7 h after vaccinia virus infection formed intermolecular duplex structures characterized as double-stranded RNA by RNase resistance, density in Cs2SO4, base composition, chromatography on cellulose, and ability to inhibit reticulocyte cell-free protein synthesis. Both sucrose gradient sedimentation and electron microscopic analysis indicated that the double-stranded regions were several hundred to more than a thousand nucleotide base pairs long. The double-stranded RNA, after denaturation, hybridized to approximately 25% of the vaccinia virus genome, whereas total late RNA hybridized to 42%. The finding that the duplex RNA, after denaturation, hybridized to most HindIII restriction endonuclease fragments of vaccinia virus DNA indicated that symmetrical transcription is not confined to the terminal inverted repeat sequence or to one contiguous region of the genome. Although relatively little labeled, early, polyadenylic acid-containing RNA formed RNase-resistant hybrids upon self-annealing, the percentage increased upon addition of unlabeled late RNA, indicating that the latter contains "anti-early" sequences.
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PMID:Intermolecular duplexes formed from polyadenylylated vaccinia virus RNA. 48 Apr 57

DNA-dependent RNA polymerase class C (or III) has been solubilized from either uninfected or adenovirus-2-infected HeLa cells and purified by chromatography on phosphocellulose, DNA-cellulose, CM-Sephadex and DEAE-Sephadex. The last column separated the enzyme into three forms CI, CII and CIII, which were completely free of RNA polymerases class A and B and of DNase and RNase. The total and the relative amount of these different enzyme C forms did not vary whether purified from uninfected or infected cells. Irrespective of the stage of purification, the three enzyme forms transcribed deproteinized adenovirus-2DNA very efficiently. This transcription was highly sensitive to elevated ionic strength (especially in the presence of Mg2+) and was accompanied by continuous reinitiation as shown by adding poly(rI), a potent inhibitor of initiation. In addition heparin-resistant initiation complexes could be formed at elevated temperature. The RNA synthesized in vitro on deproteinized intact adenovirus-2 DNA by the different forms of RNA polymerase class C, has been characterized. Analysis of the transcripts by gel electrophoresis, RNA self-annealing, hybridization to separated adenovirus-2 DNA strands and to restriction endonuclease (BamHI, HindIII), adenovirus-2 DNA fragments have demonstrated that restriction endonuclease (BamHI, HindIII), adenovirus-2 DNA fragments have demonstrated that the various regions of the adenovirus-2 genome were randomly transcribed. In addition, hybridization of RNA transcripts labelled at their 5' end by either [gamma32P]ATP or [gamma-32P]GTP indicated that not only elongation but also initiation occurred randomly through the entire adenovirus-2 genome, irrespective of the form of the enzyme and of the origin of the cells (normal or infected). The results are discussed in terms of the components which are possibly involved in specific transcription.
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PMID:Transcription in vitro of adenovirus-2 DNA by RNA polymerases class C purified from uninfected and adenovirus-infected HeLa cells. 71 Apr 51


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