Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Negatively superhelical pNS1 DNA with a molecular weight of 2.55 MDa (4 kbp) was found to contain 13 specific, unbasepaired sites that are sensitive to a single-strand-specific S1 nuclease cleavage. The S1-cleavage occurred once at these sites. In the absence of added Mg2+, the topoisomerase I purified from Haemophilus gallinarum formed a complex with the superhelical pNS1 DNA which has a hidden strand cleavage. Extensive proteinase K digestion of the complex led to cleavage of the DNA chain. Then the proteinase K-cleaved product was digested with S1, which can cut the opposite strand at the preexisting strand cleavage to generate unit-length linear DNA. Restriction endonuclease analysis of the linear DNA shows that the topoisomerase-induced cleavage occurred once at ten specific sites on the DNA. The topoisomerase caused mainly single-strand cleavage at these sites, but infrequently also caused double-strand cleavage at the same sites. Of interest is the fact that these sites considerably coincide with the S1-cleavable, unbasepaired sites.
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PMID:Correlation of enzyme-induced cleavage sites on negatively superhelical DNA between prokaryotic topoisomerase I and S1 nuclease. 630 25

Intracellular, replicative-form DNA of minute virus of mice was characterized by agarose gel electrophoresis, velocity sedimentation, electron microscopy, restriction endonuclease digestion, and sensitivity to the single-stranded nuclease S1. This analysis demonstrated the presence in murine cells infected with minute virus of mice of a 10.0-kilobase pair dimer replicative form, a 5-kilobase pair monomer replicative form, as well as a 5-kilobase viral single-stranded DNA species. Two additional viral DNA species that migrated in 0.5% agarose gels with apparent sizes of 8.0 and 5.5 kilobase pairs were also observed. Further investigation indicated that the 8.0-kilobase pair DNA represents a novel class of metastable, partially replicated, dimeric intermediates. This finding has important implications for the mechanism of parvovirus DNA replication.
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PMID:Characterization of a metastable, partially replicated dimeric intermediate of minute virus of mice. 631 65

A high mobility group (HMG) nonhistone protein fraction HMG(1 + 2), composed of HMG1 and HMG2, was prepared from pig thymus chromatin. In order to examine a possibility that the HMG(1 + 2) participates in the unwinding of the DNA double-helix, DNA hydrolysis assay systems with the endonucleases specific for single-stranded DNA were employed. In the presence of HMG(1 + 2), the hydrolysis of double-stranded DNA by N. crassa endonuclease was markedly promoted, while the hydrolysis of single-stranded DNA was hardly enhanced. The reaction kinetic data showed that the stimulation of the hydrolysis of double-stranded DNA in the presence of HMG(1 + 2) was due to the unwinding of the DNA double-helix by the HMG(1 + 2), and not due to stimulation of enzyme activity of the endonuclease by the protein. The unwinding reactions were dependent on the HMG protein concentration at low weight protein to DNA ratios and reached a maximum at the ratio of 0.025. The region unwound in the whole DNA was partial. Similar results were obtained for experiments with nuclease S1. Isolated HMG1 and HMG2 fractions showed DNA unwinding activity of similar extents. The association constant obtained by fluorescence quenching analysis showed that the HMG(1 + 2) has higher affinity to single-stranded DNA than to double-stranded DNA. The susceptibility to the unwinding differed with the DNA source. These results suggest that HMG(1 + 2) at a low weight protein to DNA ratio binds to some limited double-stranded region in DNA and unwinds the DNA partially.
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PMID:Unwinding of DNA by nonhistone chromosomal protein HMG(1 + 2) from pig thymus as determined with endonuclease. 632 90

Several papillomas from a single patient who exhibited an unusual immune deficiency syndrome were analyzed for the presence of specific human papillomavirus (HPV) types. Preliminary analysis indicated that the HPV DNA species present in each of these tissues was quite unlike any of the previously characterized HPV types. In order to more rigorously analyze the HPV from this patient we have isolated the HPV DNA by molecularly cloning it into a bacteriophage lambda vector and have constructed a detailed restriction endonuclease map. Comparative hybridization studies using S1 nuclease analyses showed 6% or less nucleotide sequence homology of this viral DNA with HPV types 1, 2, 3, 4, 5, 6, or an HPV-11, molecularly cloned in this laboratory. Moreover, Southern blot analyses under stringent hybridization conditions revealed little, if any, hybridization to HPV types 1, 2, 4, 5, 7, 8, 10, 11, HPV-EV isolated from a patient with epidermodysplasia verruciformis (EV), or 2 previously described HPVs (HPV-P and HPV-PW) related to HPV-3. There was, however, a very weak sequence homology detected with HPV-6 and an extremely weak homology to HPV-3. No filter hybridization was observed with the recently characterized HPVs 9 or -12 to -24. These data accumulatively indicate that the HPV species from this immunosuppressed patient represents a new, hitherto unidentified HPV type.
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PMID:Molecular cloning and characterization of a unique type of human papillomavirus from an immune deficient patient. 632 88

A site that is preferentially cleaved by the single-strand-specific endonuclease from Aspergillus oryzae was located in vitro 180 base pairs upstream from the 5' end of the chicken pro-alpha 2(I) collagen gene. It is found in supercoiled plasmids with a negative superhelical density of -0.024 or more but not in linear DNA molecules. The nuclease S1 sensitivity is retained in plasmids containing genomic fragments extending from position +8 to -285 (where +1 is the first transcribed base) and from -147 to -351 and also in a 5.7-kilobase EcoRI fragment that extends 1.6 kilobases 5' and 4.1 kilobases 3' to the 5' end of the gene. Analysis at the nucleotide level on a DNA sequence gel places the site at -181 to -182 on the sense strand and at -182 to -184 and -192 to -195 on the nonsense strand. These sites lie within a stretch of 42 pyrimidines interrupted by a single guanine and within the sequence T-C-C-C-T-C-C-C-T-T-C-C-T-C-C-C-T-C-C-C-T.
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PMID:Endonuclease S1-sensitive site in chicken pro-alpha 2(I) collagen 5' flanking gene region. 632 10

African swine fever virus DNA (about 170 kbp) was cleaved with the restriction endonuclease EcoRI and most of the resulting 31 fragments were cloned in either the phage vector lambda WES lambda B or the plasmid pBR325. Three fragments were not cloned in those vectors, the largest fragment EcoRI-A (21.2 kbp) and the two crosslinked terminal fragments, EcoRI-K' and D'. Endonuclease SalI cut fragment EcoRI-A into three pieces which were cloned in plasmid pBR322. The two terminal EcoRI fragments were cloned after removal of the crosslinks with nuclease S1 and addition of EcoRI linkers to the fragment ends. The complete library of the cloned fragments accounted for about 98% of ASF virus genome, the missing sequences being those removed by the nuclease S1 in the process of cloning the terminal fragments.
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PMID:Molecular cloning of African swine fever virus DNA. 632 51

The endonuclease cleavage of 41 S pre-rRNA to yield 32 S and 21 S pre-rRNA constitutes a major early step in the processing of pre-rRNA in rat liver. The 5'-terminus of 32 S pre-rRNA and the 3'-terminus of 21 S pre-rRNA were precisely located within the rDNA sequence by S1 nuclease protection mapping and use of appropriate rDNA restriction fragments. The 5'-terminus of 12 S pre-rRNA, an initial product of 32 S pre-rRNA processing, was also mapped within the rDNA sequence. The 5'-termini of 32 S and 12 S pre-rRNA coincide and map within a 14-residue T-tract (non-coding strand) at 161-163 bp upstream from the 5'-end of the 5.8 S rRNA gene. The 3'-terminus of 21 S pre-rRNA maps within the same T-tract. These results show that the endonuclease cleavage occurs within a U-tract in the internal transcribed spacer 1 sequence of 41 S pre-rRNA. The homogeneity of the 5'- or 3'-termini of 32 S, 12 S and 21 S pre-rRNA indicates also that the terminal processing of these molecules, if any, is markedly slower. The coincidence in the location of 32 S and 12 S pre-rRNA 5'-termini shows further that the endonuclease cleavage of 32 S pre-rRNA precedes the removal of its 5'-terminal segment to yield 5.8 S rRNA. The absence in the whole pre-rRNA internal transcribed spacer of sequences complementary to the target U-tract suggests that the endonuclease cleavage, generating 32 S and 21 S pre-rRNA, occurs in a single-stranded loop of U-residues.
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PMID:Mapping of the major early endonuclease cleavage site of the rat precursor to rRNA within the internal transcribed spacer sequence of rDNA. 632 37

The hepatitis B-like viruses have a approximately 3.2 kilobase, partially double-stranded DNA genome that is held in a circular conformation by a cohesive overlap between the 5' ends of the two strands. In addition, a protein is covalently bound to the 5' end of the minus strand of virion DNA. The sequence of the cohesive overlap region and its location relative to open reading frames and to the initiation site for minus-strand DNA synthesis, which occurs by reverse transcription of viral RNA, were investigated in duck hepatitis B virus. The 5' ends of virion DNA were mapped by restriction endonuclease analysis of labeled virion DNA, S1 nuclease digestion, and primer extension, using avian myeloblastosis virus DNA polymerase. The cohesive overlap region was shown to be 69 +/- 4 base pairs in length. It contained a 10-base pair inverted repeat in approximately the middle and a 12-base pair direct repeat near each end. The apparent initiation site of reverse transcription was determined by partial sequence analysis of dideoxynucleotide-truncated minus-strand DNA intermediates and comparison of their lengths with the length of a known DNA sequence. It mapped within two to four nucleotides of the 5' end of the minus strand of virion DNA. The results are consistent with the interpretation that the 5' end of the minus strand of virion DNA is the origin of reverse transcription and that the protein covalently bound to virion DNA is the primer of reverse transcription.
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PMID:Mapping of the cohesive overlap of duck hepatitis B virus DNA and of the site of initiation of reverse transcription. 632 37

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

Nucleotide sequence analysis of a recombinant cDNA for a duck alpha-globin gene indicates a gene with novel features and evolutionary history. The duck alpha-globin double-stranded cDNA, treated with S1 nuclease and tailed with poly(dC), was inserted into the PstI restriction endonuclease site of pBR322 tailed with poly(dG). Nucleotide sequence analysis of the resulting recombinant cDNA indicates that it contains the translated region and all of the 3' untranslated region for an alpha-globin gene. The sequence was determined by procedures designed especially for rapid analysis of pBR322 (PstI site) recombinant cDNAs. This duck globin has sequences related to the chicken alpha-A globin in some regions but in other regions it is more closely related to another alpha globin found in anemic chickens.
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PMID:Nucleotide sequence for a novel duck alpha-globin gene. 689 64


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