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:6.5.1.2 (DNA ligase)
2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HeLa cells contain a high M.W. form of DNA ligase which can be completely converted to a low M.W. form. Stokes radius, frictional ratio, sedimentation coefficient, molecular weight, pH dependence, and heat inactivation rate of the two forms have been studied. The major properties of the two forms of DNA ligase in HeLa cells (in particular molecular weights and pH dependence) resemble those of the "dimer" and "monomer" structures described in cultured human cells (Pedrali, G., Spadari, S., Ciarrocchi, G., Pedrini, M., Falaschi, A. (1973) Eur. J. Biochem., 39 343) . In synchronized HeLa cells, the DNA ligase shows a two fold increase during S phase and parallels the increase in the DNA synthesis rate. DNA ligase increases in parallel with viral DNA synthesis after infection of HeLa cells with vaccinia and Herpes virus but its cofactor requirements and physical properties (including the dimer leads to monomer conversion) are unchanged, suggesting that the newly formed ligase is not virus-coded.
...
PMID:Properties of DNA ligase from uninfected and virus-infected HeLa cells. 0 21

A 21.8 kbp region of the genome of variola major virus (strain Harvey), a virus that caused haemorrhagic-type smallpox, has been sequenced and shown to possess 96% nucleotide identity to the corresponding region of vaccinia virus, the smallpox vaccine. Overall the gene arrangement in the two viruses is highly similar and individual open reading frames (ORFs) display a high degree of amino acid identity, for instance 26 of the 32 variola virus ORFs have > or = 90% identity with their vaccinia virus counterparts. A remarkable difference is the disruption of seven vaccinia virus ORFs into small fragments in variola virus. These include the variola virus homologue of vaccinia virus SalF2R, which encodes a protein related to C-type animal lectins, and SalF7L, which encodes an active 3 beta-hydroxysteroid dehydrogenase enzyme that contributes to vaccinia virus virulence. Upstream of the variola virus haemagglutinin gene there is a deletion of 1910 bp so that the equivalent of vaccinia virus gene SalF17R is truncated, and SalF16R, which shows amino acid similarity to the tumour necrosis factor receptor, is absent. The region sequenced includes the genes for thymidylate kinase and DNA ligase both of which are active in vaccinia virus and are highly conserved in variola virus. Other conserved ORFs with interesting homologies are those encoding profilin, superoxide dismutase and part of guanylate kinase. Two vaccinia virus genes encoding glycoproteins of the outer envelope of extracellular enveloped virus are also conserved in variola virus and this homology is likely to have contributed to the immunological protection which vaccinia virus evoked against smallpox. Lastly, there are multiple instances in which short oligonucleotide direct repeats flank a region absent from either variola or vaccinia virus.
...
PMID:Nucleotide sequence of 21.8 kbp of variola major virus strain Harvey and comparison with vaccinia virus. 133 Dec 92

A 3382 bp fragment containing a gene for a DNA ligase from the extremely thermophilic, acidophilic, and facultatively anaerobic archaeon (archaebacterium) Desulfurolobus ambivalens was cloned and sequenced. The deduced amino acid sequence (600 amino acids, 67619 molecular weight) showed 30-34% sequence identity with the ATP-dependent eucaryal (eukaryotic) DNA ligases of Schizosaccharomyces pombe, Saccharomyces cerevisiae, the human DNA ligase I, and with the Vaccinia DNA ligase. Distant similarity to the DNA ligases from the bacteriophages T3, T4, T6, T7 and the African swine fever virus was found, whereas no similarities were detectable to the NAD-dependent DNA ligases from the bacteria (eubacteria) Escherichia coli and Thermus thermophilus, to the ATP-dependent RNA-ligase of bacteriophage T4, and to the tRNA-Ligase from S.cerevisiae. A detailed comparison of the phylogenetic relationship of the amino acid sequences of all known DNA and RNA ligases is presented including a complete alignment of the ATP-dependent DNA ligases. The in vivo-transcription initiation and termination sites of the D.ambivalens gene were mapped. The calculated transcript length was 1904-1911 nt.
...
PMID:Molecular characterisation of a DNA ligase gene of the extremely thermophilic archaeon Desulfurolobus ambivalens shows close phylogenetic relationship to eukaryotic ligases. 143 56

A DNA ligase has been purified approximately 5000-fold, to near homogeneity, from the trypanosomatid Crithidia fasciculata. The purified enzyme contains polypeptides with molecular masses of 84 and 80 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both polypeptides formed enzyme-adenylate complexes in the absence of DNA, contained an epitope that is highly conserved between human and bovine DNA ligase I and yeast and vaccinia virus DNA ligases, and were identified in fresh lysates of C. fasciculata by antibodies raised against the purified protein. Hydrodynamic measurements indicate that the enzyme is an asymmetric protein of approximately 80 kDa. The purified DNA ligase can join oligo(dT) annealed to poly(dA), but not oligo(dT) annealed to poly(rA), and can ligate blunt-ended DNA fragments. The enzyme has a low Km for ATP of 0.3 microM. The DNA ligase absolutely requires ATP and Mg2+, and is inhibited by N-ethylmaleimide and by KCI. Substrate specificity, Km for ATP, and the conserved epitope all suggest that the purified enzyme is the trypanosome homologue of DNA ligase I.
...
PMID:Purification and characterization of DNA ligase I from the trypanosomatid Crithidia fasciculata. 150 76

DNA ligase I is the major DNA ligase activity in proliferating mammalian cells. The protein has been purified to apparent homogeneity from calf thymus. It has a monomeric structure and a blocked N-terminal residue. DNA ligase I is a 125-kDa polypeptide as estimated by sodium dodecyl sulfate-gel electrophoresis and by gel chromatography under denaturing conditions, whereas hydrodynamic measurements indicate that the enzyme is an asymmetric 98-kDa protein. Immunoblotting with rabbit polyclonal antibodies to the enzyme revealed a single polypeptide of 125 kDa in freshly prepared crude cell extracts of calf thymus. Limited digestion of the purified DNA ligase I with several reagent proteolytic enzymes generated a relatively protease-resistant 85-kDa fragment. This domain retained full catalytic activity. Similar results were obtained with partially purified human DNA ligase I. The active large fragment represents the C-terminal part of the intact protein, and contains an epitope conserved between mammalian DNA ligase I and yeast and vaccinia virus DNA ligases. The function of the N-terminal region of DNA ligase I is unknown.
...
PMID:Mammalian DNA ligases. Catalytic domain and size of DNA ligase I. 169 31

The functional compatibility of vaccinia virus DNA ligase with eukaryotic counterparts was demonstrated by its ability to complement Saccharomyces cerevisiae cdc9. The vaccinia DNA ligase is a 63 kDa protein expressed early during infection that is non-essential for virus DNA replication and recombination in cultured cells. This implies complementation by a mammalian DNA ligase, yet no obvious recruitment of host DNA ligase I from the nucleus to the cytoplasm was observed during infection. An antiserum raised against a peptide conserved in eukaryotic DNA ligases identified the virus enzyme in discrete cytoplasmic 'factories', the sites of virus DNA synthesis, demonstrating immunological cross-reactivity between host DNA ligase I and the vaccinia enzyme. DNA ligase was not detected in the factories of a mutant virus lacking the ligase gene. Despite this, no difference in growth between wild-type (WT) and mutant virus was detectable even in Bloom's syndrome cells which have reduced DNA ligase I activity. However, DNA ligase negative virus showed an increased sensitivity to UV or bleomycin in cultured cells, and the importance of DNA ligase for virus virulence in vivo was demonstrated by the attenuated phenotype of the deletion mutant in intranasally infected mice.
...
PMID:Vaccinia DNA ligase complements Saccharomyces cerevisiae cdc9, localizes in cytoplasmic factories and affects virulence and virus sensitivity to DNA damaging agents. 175 39

The essentiality of the vaccinia virus DNA ligase gene, SalF 15R, for virus growth was tested by insertional mutagenesis. A plasmid containing E. coli gpt inserted within a large deletion in the DNA ligase gene was transfected into vaccinia virus-infected cells and recombinant viruses selected by three cycles of plaque purification in the presence of mycophenolic acid (MPA). Surprisingly, in some isolates, which replicated in a manner indistinguishable from wild type (WT) virus, the WT gene was replaced by the gpt allele, demonstrating that the DNA ligase gene is nonessential for growth in cultured cells. In other isolates the entire plasmid was integrated into the virus genome by a single crossover event and a functional copy of the DNA ligase was retained. Southern blot analyses of the latter, drug-resistant viruses indicated extra DNA fragments, of sizes inconsistent with predicted viral structures, which represent the plasmid products of homologous recombination. Hirt extracts from cells infected with such multiply plaque purified virus isolates yielded plasmids that produced ampicillin-resistant colonies after transformation of E. coli. These plasmids were of two structures, representing either the original plasmid used for transfection, or a plasmid containing the WT ligase gene rescued by recombination with the virus genome. Similarly, insertional mutagenesis of the vaccinia virus thymidine kinase (TK) gene with gpt yielded plasmids containing mutant or wild type TK alleles when recombinant viruses were selected in MPA. Such plasmids were not isolated when TK minus viruses were selected in 5-bromodeoxyuridine (BUdR).
...
PMID:Vaccinia virus DNA ligase is nonessential for virus replication: recovery of plasmids from virus-infected cells. 198 87

The nucleotide sequence of 42090 bp of vaccinia virus strain WR is presented. The sequence includes the SalI L, F, G and I fragments and starts near the centre of the HindIII A fragment and extends rightwards towards the genomic terminus, finishing approximately 0.5 kb internal of the inverted terminal repeat (ITR). Translation of this region has identified 65 open reading frames (ORFs) of greater than 65 amino acids in length. Fifty-one of these which do not extensively overlap other larger ORFs have been subjected to further analysis; the other 14 are termed minor ORFs. In the rightmost 28.7 kb, the genes are, with one exception, transcribed towards the genomic terminus, similar to the arrangement of genes at the left end of the virus genome. Internal of this region the genes are expressed off either DNA strand but still predominately rightwards. ORFs are tightly packed with few intergenic non-coding regions of greater than 250 bp. Protein sequence comparisons have established a remarkably high number of homologies with entries in existing protein databases. Of these, DNA ligase, thymidylate kinase, two serine-threonine protein kinases, two serine proteinase inhibitors (serpins), two interleukin-1 receptor homologous and a discontinuous ORF related to tumour necrosis factor receptor have been reported. Other homologies include lectins, profilin, 3 beta-hydroxy steroid dehydrogenase, superoxide dismutase, guanylate kinase, ankyrin and complement factor H. In addition, there are a number of polypeptides with predicted properties of membrane-associated, secretory or glyco-proteins. Twelve gene families are described here and elsewhere. There is considerable similarity between genes from the right and left end of the virus genome that may have arisen by terminal transposition events. Several differences from the corresponding region of vaccinia virus strain Copenhagen sequence are noted. Near the right terminus the sequences diverge completely, and internal of this there are multiple examples of deletion of short sequences (eight to 10 nucleotides) that lie within penta- or hexanucleotide direct repeats.
...
PMID:Nucleotide sequence of 42 kbp of vaccinia virus strain WR from near the right inverted terminal repeat. 204 93

Recent studies on eukaryotic DNA ligases are briefly reviewed. The two distinguishable enzymes from mammalian cells, DNA ligase I and DNA ligase II, have been purified to homogeneity and characterized biochemically. Two distinct DNA ligases have also been identified in Drosophila melanogaster embryos. The genes encoding DNA ligases from Schizosaccharomyces pombe, Saccharomyces cerevisiae and vaccinia virus have been cloned and sequenced. These 3 proteins exhibit about 30% amino acid sequence identity; the 2 yeast enzymes share 53% amino acid sequence identity or conserved changes. Altered DNA ligase I activity has been found in cell lines from patients with Bloom's syndrome, although a causal link between the enzyme deficiency and the disease has not yet been proven.
...
PMID:Eukaryotic DNA ligases. 220 27

Biochemical and genetic analyses have been conducted to determine whether a vaccinia virus open reading frame (orf) with extensive homology to the Saccharomyces cerevisiae DNA ligase gene encodes a functional ligase activity. This orf in HindIII A, designated A50R, is capable of encoding a 552-amino-acid, 63.4-kDa polypeptide. Full-length A50R mRNA produced in vitro directed the synthesis of a polypeptide with an apparent molecular weight of 57 kDa. Significantly, translation reactions programmed with A50R mRNA were capable of ligating a 3-kb Notl restriction fragment into multimers. DNA ligase activity was not detectable when either truncated sense or full-length antisense mRNA was translated in vitro. In extracts prepared from cells infected with wt vaccinia virus, DNA ligase activity was detected as assayed by the formation of a 57 kDa ligase-AMP adduct which was expressed early in the viral replication cycle. In cells infected with a DNA ligase deletion mutant no equivalent AMP-labeled adduct was detected. Relative to wt virus, the DNA ligase deletion mutant exhibited no significant differences in homologous recombination. These results indicate that the vaccinia orf A50R encodes a functional DNA ligase expressed early in infection, but this DNA ligase is nonessential for either recombination or viral replication.
...
PMID:A DNA ligase gene in the Copenhagen strain of vaccinia virus is nonessential for viral replication and recombination. 221 23


1 2 3 4 Next >>

---