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

---

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

The aim of this paper was to test the possibility to ligate and hydrolyse DNA sequences containing thiomodified ends and bonds. T4 DNA ligase was shown to ligate DNA fragments regardless of whether it contains phosphorylated or thiophosphorylated 5'-end. But the cleavage of an internally thiomodified phosphodiester bond was found to be totally inhibited when using the non-palindromic restrictase Bbs I. The special properties of this restriction endonuclease should allow the development of an oriented cloning strategy when combined with T4 ligase and a thiophosphorylation of DNA fragments.
...
PMID:The accessibility of thiophosphorylated groups in DNA fragments to the enzymatic activity of ligases and restriction endonuclease Bbs I. 758 Sep 99

Pronuclear injection is currently the most often used method to make transgenic animals, but in some animal species it is temporally restrictive due to difficulty in visualizing pronuclei. However, the injection of construct DNA into the cytoplasm does not result in transgenesis. The production of transgenic mice by a cytoplasmic microinjection technique of polylysine complexed DNA into pronuclear stage zygotes is described. Transgenic mice were produced from cytoplasmic microinjection of mixtures of a 5.3 kb linearized DNA and poly-L-lysine (degree of polymerization = 51). Effects on transgenic frequency of both the lysine to phosphate ratio of polylysine to DNA and DNA concentration were studied. About 12.8% of the pups born from zygotes cytoplasmically microinjected with a polylysine/DNA mixture having a lysine to phosphate ratio (L:P) of 1:1 at a DNA concentration of 50 micrograms ml-1 were transgenic. The transgenic frequency for the pronuclear microinjection positive control of DNA alone was 21.7%. No transgenic pups were born from microinjection of DNA alone into the cytoplasm. Complexes of polylysine/DNA were detected using agarose gel electrophoresis at the conditions which produced transgenic mice. The presence of polylysine with construct DNA altered the in vitro activities of restriction endonuclease and DNA ligase on the construct DNA. The production of transgenic animals using DNA and polylysine in the absence of any other signal protein suggests that a DNA/polylysine complex but not DNA alone can act as a substrate for transgenesis from the cytoplasm.
...
PMID:Transgenesis in mice by cytoplasmic injection of polylysine/DNA mixtures. 758 16

Chronic exposure to dimethylnitrosamine produces hepatic tumors through recurrent DNA alkylation, whereas acute exposure can cause liver necrosis through mechanisms that remain largely unknown. Our laboratory recently demonstrated that DNA fragmentation occurs early on and may be a causal event in dimethylnitrosamine-induced necrosis in liver. A challenge to interpreting these results is that up to 30% of liver cells are non-parenchymal and could account for the observed DNA fragmentation. In the present study, we have examined whether dimethylnitrosamine induces early genomic DNA fragmentation in cultured mouse hepatocytes. Hepatic parenchymal cells isolated from male ICR mice were cultured in Williams E medium. DNA damage was assessed quantitatively as a fragmented fraction that was not sedimented at 27,000 x g, and qualitatively from agarose gel electrophoresis. Cellular response to DNA damage was assessed by measuring induction of the DNA repair enzyme DNA ligase. Toxic cell death was estimated from release of lactate dehydrogenase (LDH) or adenine nucleotides from cells prelabeled with [3H]adenine. Dimethylnitrosamine produced a twofold increase in [3H]adenine release by 6 h and LDH release at 36 h. DNA fragmentation and DNA ligase activity increased by as early as 1 h. The Ca(2+)-endonuclease inhibitor aurintricarboxylic acid and the Ca2+ chelator ethylenediamine tetraacetic acid (EDTA) prevented DNA fragmentation through 6 h and virtually abolished cytotoxicity through 30 h. DNA ligase induction was strongly associated with DNA fragmentation. Early increases in DNA fragmentation and DNA ligase were highly correlated with later toxic cell death. Such results strongly suggest that dimethylnitrosamine-induced fragmentation of DNA in target parenchymal cells is a causal factor in the toxic death of these liver cells.
...
PMID:Dimethylnitrosamine-induced DNA damage and toxic cell death in cultured mouse hepatocytes. 766 92

We have constructed rare restriction-site (NotI, SacII and ClaI) chromosome 3 (Chr 3)-specific linking libraries in a plasmid-based vector by mass transfer of a lambda phage human Chr-3-specific library (LA03NS01-ATCC57717) into pUC18. Total plasmid DNA isolated from the plasmid-based Chr-3-specific library was digested with either ClaI, NotI or SacII. Linear molecules were separated from undigested circles by pulsed-field polyacrylamide-gel electrophoresis. Purified linear molecules were circularized with T4 DNA ligase and transformed into bacteria. The resulting clones were greatly enriched for sequences recognized by the original restriction endonuclease used for digestion (83 to 95%). These sublibraries are composed of 600 (NotI) 1000 (SacII) or 30,000 (ClaI) clones. Thus, this procedure allows for easy isolation of Chr-3-specific DNA clones containing a variety of rare restriction sites. Sequence-tagged site (STS) data are also presented for five site-specifically mapped Chr-3-specific DNA clones. These studies may facilitate the construction of region specific linking libraries for mapping of various disease-specific loci on Chr 3.
...
PMID:Construction of rare restriction site (NotI, SacII and ClaI) linking libraries and sequence-tagged site analysis of single-copy clones from a human chromosome-3-specific library. 782 99

Oxidation of DNA and its components can cause genetic mutations and chromosomal instability. These changes have generally been implicated in aging. Oxidation of the methyl group of thymidine residues in DNA is known to result in the formation 5-hydroxymethyl-2'-deoxyuridine (5HmdUrd). We have utilized Bacillus subtilis phage SPO1 DNA as a model of oxidatively damaged DNA. In this phage, all thymine (Thy) residues are replaced by 5-hydroxymethyluracil (5HmUra), but the species is naturally devoid of other oxidatively-induced DNA lesions. Particular attention was paid to the behavior of 5HmUra-containing DNA as a target for several enzymes employing DNA as substrate; restriction endonucleases, dam DNA methylase and T4 DNA ligase. We noticed that susceptibility of SPO1 DNA varied when different restriction endonucleases having 5HmUra in the restriction sites were tested. Endonucleolytic cleavage brought about Sau3A proceeded as effectively with SPO1 DNA as with conventional DNA (lambda phage). The same was true when the ligation of Sau3A sites was performed with T4 DNA ligase. In contrast, both endonucleolytic cleavage and ligation were slower in SPO1 DNA, compared with lambda phage, when Taq I and T4 DNA ligase were used for restriction and ligation, respectively. We also noticed that SPO1 phage does not naturally contain N6-methyladenine (N6MeAde) opposite 5HmUra, i.e., no hydrolysis of SPO1 DNA was observed when assessed with methylation-dependent restriction endonuclease DpnI. Our results show that the presence of 5HmUra in the respective site of DNA does not, per se, prevent the activity of restriction endonucleases, ligases or DNA methylases. These data support the view that oxidation of Thy to 5HmUra in target DNA does not necessarily result in substantial deterioration in the functions of DNA processing enzymes.
...
PMID:Restriction, methylation and ligation of 5-hydroxymethyluracil-containing DNA. 786 75

A mammalian endonuclease that resolves Holliday junctions has been partially purified from extracts of calf thymus and Chinese hamster ovary cells. The activity acts upon (i) synthetic Holliday junctions and (ii) recombination intermediates made by the Escherichia coli RecA protein and appears to be functionally analogous to the E. coli RuvC protein. Cleavage occurs by the introduction of symmetrically related nicks in strands of like polarity to produce nicked duplex DNA products. The nicks can be repaired by DNA ligase. The resolvase is specific for Holliday junctions and does not act upon Y junctions, G/A mismatches, or heterologous loops. The substrate specificity is therefore similar to that of E. coli RuvC protein and contrasts with the broad range specificity of other junction resolvases such as T4 endonuclease VII. The mammalian resolvase activity has been observed at normal levels in extracts prepared from a series of DNA repair-defective cells. These include the x-ray or UV-sensitive hamster lines xrs-5, xrs-6, and Chinese hamster ovary 43-3B (defective in ERCC-1), and murine cells that are severely immunodeficient and defective in both V(D)J rejoining and DNA repair.
...
PMID:Resolution of recombination intermediates by a mammalian activity functionally analogous to Escherichia coli RuvC resolvase. 810 2

We have purified a high molecular weight complex (RC-1) from calf thymus nuclei that catalyzes a recombinational repair of double-strand gaps and deletions in DNA by gene conversion as well as cross-over events leading to cointegrant products. These have been detected by polymerase chain reaction analysis using oligonucleotide primer pairs that detect joined sequences originally present on only one or the other of the recombination substrates. RC-1 has an apparent molecular mass of about 550-600 kDa and contains at least five polypeptide chains: molecular masses about 230, 210, 160, 130, and 40 kDa. RC-1 contains a DNA polymerase, identified as DNA polymerase epsilon, that co-purifies with RC-1. A DNA ligase, most likely mammalian DNA ligase III, and a 5'-3' exonuclease also copurify with the RC-1. Most preparations of RC-1 contain low levels of a double-strand endonuclease, 3'-5' exonuclease and single-strand nuclease activities. However, DNA helicase, terminal deoxynucleotidyl transferase, or DNA topoisomerase I and II were not detected in RC-1. The DNA polymerase and DNA ligase in RC-1 can act in concert to repair a multiply gapped DNA to a covalently repaired duplex. The bovine single-strand-binding protein stimulates the formation of the recombination products and the repair reaction mentioned above about 4-fold.
...
PMID:A mammalian protein complex that repairs double-strand breaks and deletions by recombination. 839 64

A general solid-phase method for the site-directed mutagenesis of double-stranded DNA (dsDNA) is described. Plasmid DNA is linearized using either a restriction endonuclease (ENase) or the RecA-assisted ENase or RecA-AC cleavage method. Alternatively, PCR may be used to generate linear dsDNA. One or both strands of the DNA is biotinylated and attached to a solid support, and the DNA strands are separated using 0.2 M NaOH. An extension oligodeoxyribonucleotide (oligo) and a single or multiple oligo(s) containing the desired mutation(s) are annealed to one of the bound DNA strands and used to initiate the synthesis of a complementary strand by a nonstrand-displacing DNA polymerase. The in vitro synthesized strand incorporating the desired alteration(s) is melted off of the support and recircularized using one of several types of bridging oligos, DNA ligase, and a DNA polymerase and transformed into the host. Greater than 90% mutagenic efficiency has been obtained using this method.
...
PMID:A method for the site-directed mono- and multi-mutagenesis of double-stranded DNA. 847 60

Exposure of DNA to ionising radiation produces a variety of lesions. Double-strand breaks are repaired by recombinational pathways including a rapid single-strand annealing process which results in deletion of DNA sequences, and a double-strand break repair pathway which conserves genetic information. Single-strand breaks are repaired by the sequential action of a 3'-phosphodiesterase, DNA polymerase beta and a DNA ligase. Damaged bases are excised by DNA glycosylases, and a single-base gap introduced, either by the action of an AP endonuclease activity and a DNA deoxyribophosphodiesterase, or by the AP lyase activity of the glycosylase and an AP endonuclease. Repair is completed by DNA polymerase beta and a DNA ligase.
...
PMID:The repair of ionising radiation-induced damage to DNA. 851 49

Recombination protein complex RC-1, purified from calf thymus nuclear extracts, catalyzes cell-free DNA strand transfer and repair of gaps and deletions through DNA recombination. DNA polymerase E, DNA ligase III and a DNA structure-specific endonuclease co-purify with the five polypeptide complex. Here we describe the identification of two hitherto unknown subunits of RC-1. N-terminal amino acid sequences of the 160 and 130 kDa polypeptides display up to 100% identity to proteins of the structural maintenance of chromosomes (SMC) subfamilies 1 and 2. SMC proteins are involved in mitotic chromosome segregation and condensation, as well as in certain DNA repair pathways in fission (rad18 gene) and budding (RHC18 gene) yeast. The assignment was substantiated by immuno-cross-reactivity of the RC-1 subunits with polyclonal antibodies specific for Xenopus laevis SMC proteins. These antibodies, and polyclonal antibodies directed against the bovine 160 and 130 kDa polypeptides, named BSMC1 and BSMC2 (bovine SMC), inhibited RC-1-mediated DNA transfer, indicating that the SMC proteins are necessary components of the reaction. Two independent assays revealed DNA reannealing activity of RC-1, which resides in its BSMC subunits, thereby demonstrating a novel function of these proteins. To our knowledge, this is the first evidence for the association of mammalian SMC proteins with a multiprotein complex harboring, among others, DNA recombination, DNA ligase and DNA polymerase activities.
...
PMID:SMC proteins constitute two subunits of the mammalian recombination complex RC-1. 867 Sep 10


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---