Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.5.1.2 (DNA ligase)
 2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Nucleotide sequence of 21.8 kbp of variola major virus strain Harvey and comparison with vaccinia virus. 133 Dec 92

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.
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PMID:Nucleotide sequence of 42 kbp of vaccinia virus strain WR from near the right inverted terminal repeat. 204 93

We have cloned CDC9, the structural gene for Saccharomyces cerevisiae DNA ligase, and investigated its transcriptional regulation both as a function of cell cycle stage and after UV irradiation. The steady-state level of DNA ligase mRNA increases at least fourfold in late G1, after the completion of start but before S phase. This high level of CDC9 mRNA then decays with an apparent half-life of ca. 20 min and remains at a low basal level throughout the rest of the cell cycle. The accumulation of CDC9 mRNA in late G1 is dependent upon the completion of start but not the CDC7 and CDC8 functions. Exposure of cells to UV light elicits an eightfold increase in DNA ligase mRNA levels.
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PMID:Regulation of CDC9, the Saccharomyces cerevisiae gene that encodes DNA ligase. 388 10

A fragment of 4156 bp of fowlpox virus (FPV) genomic DNA contains homologues of vaccinia virus 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD; A44L) and DNA ligase (A50R) genes. The FPV locus has clearly been rearranged relative to that of vaccinia virus as homologues of genes A45R to A49R, including the thymidylate kinase and a gene with homology to superoxide dismutase, are deleted. The deleted genes are replaced by two open reading frames: for a serine proteinase inhibitor with homology to vaccinia virus gene K2L and for a protein with no significant homology to proteins in the databases. In addition, the FPV homologues of A44L and A50R are in the same polarity in FPV whereas they are in opposite polarities in vaccinia virus. Increased 3 beta-HSD activity has been demonstrated in cells infected with either of two different strains of FPV or with canarypox virus.
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PMID:Deletion of fowlpox virus homologues of vaccinia virus genes between the 3 beta-hydroxysteroid dehydrogenase (A44L) and DNA ligase (A50R) genes. 807 53

The purpose of this review is to summarize information published since 1990 on DNA replication, recombination and repair of vaccinia virus, a poxvirus. Temperature-sensitive mutations reveal four essential genes related to viral DNA replication: the E9L DNA polymerase, B1R protein kinase, D5R protein, and D4R uracil DNA glycosylase. Other proteins are likely to be also involved in viral DNA replication: the H6R DNA topoisomerase, I3L single stranded-DNA binding protein, H5R virosome-associated protein, and A50R DNA ligase. In addition, several viral-encoded proteins do regulate the level of the deoxyribonucleoside triphosphate pool: the J2R thymidine kinase, A48R thymidylate kinase, 14L and F4L subunits of ribonucleotide reductase, and F2L dUTPase. Despite the apparent simplicity of the mechanism of vaccinia virus DNA replication, several important questions related to the three Rs remain unsolved.
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PMID:Vaccinia virus DNA replication: a short review. 882 74

Mammalian DNA polymerase beta is a DNA repair enzyme expressed constitutively at a low level. In vitro, purified DNA polymerase (Pol) beta incorporates the nucleotide analogues 2'-3' deoxycytidine (ddC)-triphosphate and 3'-azido-3'-deoxythymidine (AZT)-triphosphate into DNA, causing chain termination. We have tested the possibility of enhancing the cytotoxicity of these chain terminators against mammalian cells by increasing the level of Pol beta. Chinese hamster ovary AA8 and murine melanoma B16 cell lines were stably transfected with rat pol beta cDNA under the control of a viral enhancer/promoter. We found that overexpression of Pol beta sensitized the cells to ddC and AZT. To confirm the role of this polymerase in this process, we prepared cell extracts from the control and Pol beta overexpressing Chinese hamster ovary cell lines and tested in vitro their capacity to incorporate ddC-triphosphate and AZT-triphosphate into DNA. We found that inhibition of DNA replication by both chain terminators was more pronounced when extracts from pol beta-transfected cells were used, providing a direct evidence of the involvement of Pol beta in the sensitization process. In addition, we showed that cotransfection with bacterial or viral thymidine/thymidylate kinase genes enhanced the Pol beta-mediated cytotoxicity of AZT, suggesting that phosphorylation and polymerization activities might be combined to potentiate their respective effects. These observations may be useful for improving therapeutic efficiency of DNA chain terminators.
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PMID:Overexpression of DNA polymerase beta sensitizes mammalian cells to 2',3'-deoxycytidine and 3'-azido-3'-deoxythymidine. 898 50

Pseudomonas aeruginosa phage EL is a dsDNA phage related to the giant phiKZ-like Myoviridae. The EL genome sequence comprises 211,215 bp and has 201 predicted open reading frames (ORFs). The EL genome does not share DNA sequence homology with other viruses and micro-organisms sequenced to date. However, one-third of the predicted EL gene products (gps) shares similarity (Blast alignments of 17-55% amino acid identity) with phiKZ proteins. Comparative EL and phiKZ genomics reveals that these giant phages are an example of substantially diverged genetic mosaics. Based on the position of similar EL and phiKZ predicted gene products, five genome regions can be delineated in EL, four of which are relatively conserved between EL and phiKZ. Region IV, a 17.7 kb genome region with 28 predicted ORFs, is unique to EL. Fourteen EL ORFs have been assigned a putative function based on protein similarity. Assigned proteins are involved in DNA replication and nucleotide metabolism (NAD+-dependent DNA ligase, ribonuclease HI, helicase, thymidylate kinase), host lysis and particle structure. EL-gp146 is the first chaperonin GroEL sequence identified in a viral genome. Besides a putative transposase, EL harbours predicted mobile endonucleases related to H-N-H and LAGLIDADG homing endonucleases associated with group I intron and intein intervening sequences.
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PMID:Genome comparison of Pseudomonas aeruginosa large phages. 1625 35