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 messenger RNAs encoding two late adenovirus serotype 2 (Ad2) proteins, fiber and 100K, were purified by hybridization to restriction endonuclease fragments of Ad2 DNA followed by electrophoresis on polyacrylamide gels containing 98% formamide. The 5' terminal oligonucleotides generated by RNAase T1 digestion of the messengers were selected by dihydroxyboryl-cellulose chromatography. Both mRNAs gave an identical 5'-undecanucleotide with the general structure 7mG5'ppp5'AmC(m)U(C4,U3)G. This undecanucleotide could be removed by mild RNAase treatment from the mRNA after hybridization to DNA fragments containing the main coding sequence of the messenger. In contrast, a small region defined by Bal I-E (14.7-21) protects this undecanucleotide from RNase. A second region contained within both Hind III-B (17-31.5) and Hpa I-F (25.5-27.9), although unable to protect the undecanucleotide, hybridizes to both fiber and 100K mRNAs and protects a similar sequence of 100-150 nucleotides. These observations suggest that both mRNAs contain a long common sequence, complementary to at least two different sites on the Ad2 genome remote from the start of these two genes. The implications of these findings are discussed, and a general mechanism is presented for the biosynthesis of mRNAs from larger precursor molecules, based on intramolecular ligation.
Cell 1977 Sep
PMID:Two adenovirus mRNAs have a common 5' terminal leader sequence encoded at least 10 kb upstream from their main coding regions. 90 21

The larval mtDNA isolated from D. virilis, D. simulans and D. melanogaster exists in complex molecular forms in addition to the simple monomeric circular form. The frequency of circular dimers and oligomers is highly elevated in apparently normal larval tissues. These complex forms of mtDNA are separable on agarose gels. Hind III restriction endonuclease and electron microscopic analyses used in the present study have revealed that circular dimers are simply the circular concatemers of two monomeric circles which are arranged in a head-to-tail structure with no detectable heterologous regions such as insertions or deletions. The electrophoretic patterns of Hind III digested mtDNAs of D. simulans and D. melanogaster (sibling species) are identical and distinguishable from that of distantly related species, D. virilis.
Nucleic Acids Res 1977 Sep
PMID:Complex mitochondrial DNA in Drosophila. 90 97

The procedure for isolation of nucleotide pyrophosphatase (E.C. 3.6.1.9.) from potato has been modified to yield an endonuclease-free preparation purified 2300-fold. The enzyme was used for specific cleavage of pyrophosphate linkages in the 5'-terminal cap (m7GpppN) of several eukaryotic messenger RNAs. Enzymatic removal of 5'-terminal pm7G from reovirus, rabbit globin and Artemia salina mRNAs resulted in an almost complete loss (greater than 80%) of their template activities in a cell-free protein synthesizing system from wheat germ. Incubation with nucleotide pyrophosphatase did not decrease the translation of phage f2 RNA in an Escherichia coli cell-free system.
Nucleic Acids Res 1977 Sep
PMID:Removal of 5'-terminal m7G from eukaryotic mRNAs by potato nucleotide pyrophosphatase and its effect on translation. 90 99

In previous work, linear duplex molecules of adeno-associated virus, type 2 (AAV2), DNA were cleaved with the restriction endonucleases R-EcoRI, R-HindII, and R-HindIII. The physical order of the specific fragments obtained was deduced and oriented with respect to the DNA strand polarity and the direction of transcription. Stable AAV RNA is transcribed only from 70% of the minus DNA strand. We report here RNA-DNA hybridization experiments using these restriction fragments to obtain a more accurate map of the portion of the AAV genome represented in stable RNA. The data obtained with several sets of restriction fragments annealed to either whole-cell RNA or poly(A)-containing RNA were internally consistent. The AAV RNA annealed with a continuous region of the AAV DNA, beginning at 0.18 map units (18%) from the left end of the molecule and ending at 0.88 map units. In addition, the restriction endonuclease BamHI was found to make one specific cleavage in AAV2 DNA at 0.22 map units, which is 0.04 map units (i.e., 160 nucleotides) to the right (""down stream'') of the point corresponding to the 5' end of the viral mRNA.
J Virol 1976 Sep
PMID:Genome localization of adeno-associated virus RNA. 97 29

Cytoplasmic RNA sequences produced in HeLa cells infected with the adeno-virus 5 temperature-sensitive mutants ts1, ts2, ts9, ts17, ts18, ts19, ts20, ts22, ts49, ts36, and ts125 were characterized by hybridization to DNA probes generated by strand separation of restriction endonuclease fragments of adenovirus 5 DNA. Two ""early'' mutants defective in DNA synthesis, ts125 and ts36, fail to make wild-type levels of all previously reported classes of late RNA at the nonpermissive temperature. At 40.5 degrees C, both ts125 and ts36 synthesize a wild-type complement of early cytoplasmic RNA 16 h after infection. Under these conditions, no ""late'' cytoplasmic RNA sequences were observed. Similarly, nuclear RNA present in these cells resembled early cytoplasmic RNA rather than late nuclear RNA. All the late adenovirus 5 temperature-sensitive mutants synthesized normal wild-type levels of late cytoplasmic RNA at the nonpermissive temperature, except ts2, which appears to overproduce certain cytoplasmic species.
J Virol 1976 Sep
PMID:Adenovirus transcription. IV. Synthesis of viral-specific RNA in human cells infected with temperature-sensitive mutants of adenovirus 5. 97 34

We reported earlier that the addition of double-stranded RNA and ATP increases the endonuclease activity more in an extract of Ehrlich ascites tumor cells which have been treated with an interferon preparation than in a comparable extract from control cells. We report here that the addition of double-stranded RNA to an extract from Ehrlich ascites tumor cells which have been treated with an interferon preparation [or with the interferon inducer poly(I)-poly(C)] promotes the phosphorylation by [gamma-32P]ATP of at least two proteins: P1 (molecular weight of 64,000) and P2 (molecular weight of 37,000). Double-stranded RNA also promotes the phosphorylation of at least one (i.e., P1) of these two proteins in an extract from cells which have not been treated with interferon, but the extent of phosphorylation is much smaller. Double-stranded RNA which has been degraded by RNase III, or DNA, does not promote the phosphorylation.
Proc Natl Acad Sci U S A 1976 Sep
PMID:Interferon, double-stranded RNA, and protein phosphorylation. 106 6

The freshly prepared crude cytoplasmic fraction of aqueously extracted KB cells contains a single major species of DNA polymerase activity (DNA polymerase C) that sediments homogeneously in low ionic strength sucrose gradients with a peak at 10.8 S. The enzyme activity from frozen crude extracts sediments heterogeneously under these conditions with peaks at 8.4 and 10 S. In 0.45 M salt-containing gradients all of the polymerase activity is recovered as a single 6.4 S species. When purified to a specific activity of 7,300, DNA polymerase C sediments in low ionic strength gradients as a single species of 6.5 S. From combined sedimentation and gel filtration analysis, we estimate the molecular weight of the active protomeric species of the polymerase to be about 170,000. Under no conditions of ionic strength does the enzyme disaggregate to active species smaller than 6.4 to 6.5 S. Sodium dodecyl sulfate-polyacrylamide gel analysis of the most highly purified enzyme fractions reveals two major protein bands of 87,000 and 175,000 daltons, respectively. These data suggest that DNA polymerase C contains an 87,000-dalton component and permit the interpretation that the active protomer of Mr equal 170,000 may be a dimer. The purified enzyme shows maximal activity with gapped duplex DNA and has an absolute requirement for 3'-hydroxyl termini. It utilizes initiated polydeoxynucleotide templates poorly and initiated polyribonucleotide templates not at all. Although the polymerase is inhibited by PPi it has only minimal ability to promote PPi exchange (0.8% of the polymerase activity). The purified enzyme is free of endonuclease and exonuclease activities (less than or equal to 0.003% of the polymerase activity) and demonstrates no primer-template-dependent conversion of substrate dNTP to free dNMP during the polymerization reaction. Finally, DNA polymerase C does not excise misparied primer termini from a synthetic homopolymer primer-template but can utilize such termini as initiation sites, although at a very slow rate.
J Biol Chem 1975 Sep 10
PMID:"Cytoplasmic" deoxyribonucleic acid polymerase. Structure and properties of the highly purified enzyme from human KB cells. 109

Plasmid lambdadv1, which is in a dimeric form, was converted to a linear monomer duplex by the action of EcoRI restriction endonuclease that incises at a unique site in this plasmid genome. The resulting products were then joined by Escherichia coli DNA ligase to produce molecules with various oligomeric forms, and from these monomeric, dimeric, or trimeric circular molecules were purified. By transformation of cells with these DNAs, clones were obtained that carried lambdadv1 in a monomeric or dimeric form. The former type of clones have not been generated in vivo, except for one in a different host strain, and carriers of timeric or tetrameric lambdadv1's have not been obtained so far. It was observed that a considerable fraction of these oligomeric circular DNAs were converted to lower oligomers (e.g., from trimer to dimer) during transformation. The characteristics of the monomeric lambdadv1 carriers obtained were compared with those of dimeric lambdadv1 carriers. The stabilities of the plasmids of the two forms were the same. However, the monomeric plasmid carriers were less tolerant to lambdavir phage infection and perpetuated about 30% less plasmid genomes in monomer units. Furthermore, dimeric plasmid carriers appeared spontaneously and accumulated in cultures of the monomeric lambdadv1 carriers.
J Virol 1975 Sep
PMID:In vitro construction of different oligomeric forms of lambdadv DNA and studies of their transforming activities. 109 30

Replicating DNA molecules of a deletion mutant of the conjugative R-plasmid R 6 K are cleaved at a single site by the EcoRI restriction endonuclease. Electron microscope examination and measurements of the EcoRI treated replicative intermediate molecules indicate that replication can be initiated at two sites on the plasmid DNA molecule. The two sites are located at about 23 and 39% of total length, respectively, from the EcoRI cleavage site. About 5% of the replicating molecules use both replication initiation sites simultaneously.
Mol Gen Genet 1975 Sep 15
PMID:Two replication initiation sites on R-plasmid DNA. 110 50

In a temperature-sensitive mutant of E. coli defective in tRNA biosynthesis, many tRNA precursors, including monomeric and multimeric forms, accumulate. Some of the multimeric precursors contain three or more tRNA sequences within a molecule. These large precursors were cleaved by cell extracts first into intermediate size pieces which were subsequently processed by RNase P. On the basis of heat stability of mutant cell extracts, the endonuclease responsible for the initial cleavage appears to be distinct from RNase P and is designated RNase O. One of the monomeric precursors was shown to be processed first by RNase P and the product subsequently cleaved further into a smaller molecule. The nuclease responsible for this second cleavage also appears to be distinct from RNase P and is designated RNase Q. The functions of these nucleases are sequential in the trimming process with respect to that of RNase P; RNase O works prior to RNase P and RNase Q after RNase P but in both cases, not vice versa.
Proc Natl Acad Sci U S A 1975 Sep
PMID:Sequential processing of precursor tRNA molecules in Escherichia coli. 110 44


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