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)

The dam-3 mutation results in a five-fold reduction in the number of 6-methyl-adenine (6-meA) residues in the DNA of E. coli K12 or phage lambda. The DNA of phage fd appears to be devoid of 6-meA when propagated on dam-3 bacteria. The phenotypic differences between dam-3 and dam+ bacteria include: (i) increased free phage in lysogenic dam-3 cultures, (2) increased sensitivity to methyl methanesulfonate (MMS), (3) inviability of dam-3 lex-I strains, (4) lower molecular weight of DNA in dam-3 bacteria in the absence of DNA ligase and (5) increased rate of DNA degradation in dam-3 recA strains.
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PMID:Pleiotropic effects of a DNA adenine methylation mutation (dam-3) in Escherichia coli K12. 16 79

Toluene treated cells have been used to study the processes of DNA synthesis and DNA degradation in ultra-violet irradiated Escherichia coli K12. Synthesis and degradation are both shown to occur extensively if polynucleotide ligase is inhibited, and to occur to a much lesser extent if ligase activity is optimal. Extensive UV-induced DNA synthesis in toluene-treated cells requires ATP for the initial incision step, and DNA polymerase I. Extensive degradation also depends on the early ATP-dependent incision step, and the subsequent degradation shows a partial requirement for ATP. Curtailment of degradation by ligase requires DNA polymerase activity, but is not dependent upon DNA polymerase I. Apparently this process can be carried out with equal facility by either DNA polymerase II or polymerase III. These observations suggest that extensive DNA polymerase I-dependent repair synthesis and extensive DNA degradation are facets of two divergent pathways of excision repair, both of which depend upon the early uvrABC determined ATP-dependent incision step.
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PMID:DNA synthesis and degradation in UV-irradiated toluene treated cells of E. coli K12: the role of polynucleotide ligase. 34 Sep 17

We have examined DNA strand breakage, DNA degradation, and the rate of DNA synthesis in lig and lig-recB strains of Escherichia coli K12 incubated in the presence and absence of 3 mug/ml chloramphenicol. Substantial DNA strand breakage and DNA degradation is observed in the lig strain upon growth at 40 degrees C; however, such strand breakage and DNA degradation is not observed in th lig-recB strainl Incubation of the lig strain at 40 degrees C in the presence of 3 mug/ml chloramphenicol reduces the amount of DNA strand breakage and DNA degradation to the level observed in the lig-recB strain. Together, these results demonstrate that exonuclease V (the recBC gene product) is responsible for the increased DNA degradation associated with DNA ligase deficiency.
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PMID:Effect of chloramphenicol and the recB gene product on DNA metabolism in Escherichia coli K12 strains defective in DNA ligase. 78 29

T4+ exhibits increased ultraviolet sensitivity on derivatives of Escherichia coli K12 or B lacking deoxyribonucleic acid (DNA) polymerase I. However, the sensitivity of T4v is not affected by the absence of host DNA polymerase. T4x and T4y also show increased sensitivity on DNA polymerase-deficient strains, but to a lesser extent than observed with wild-type T4. When T4x or T4y, but not T4+, are plated on a double mutant lacking both DNA polymerase and the uvrA gene product, a partial suppression of the polymerase effect is observed. Host ligase appears to be able to suppress to some extent the T4y phenotype but has no effect on wild-type T4 or other T4 mutants. T4xv incubated in E. coli B or B(s-1) in the presence of chloramphenicol (50 mug/ml) shows increased resistance over directly plated irradiated phage. Increased survival under the same conditions was not observed with T4+ or other T4 mutants. The repair of X-ray-damaged T4 was investigated by examining survival curves of T4+, T4x, T4y, T4ts43, and T4ts30. The repair processes were further defined by observing the effects of plating irradiated phage on various hosts including strains lacking DNA polymerase I or polynucleotide ligase. Two classes of effects were observed. Firstly, the x and y gene products seem to be involved in a repair system utilizing host ligase. Secondly, in the absence of host DNA polymerase, phage sensitivity is increased in an unknown manner which is enhanced by the presence of host uvrA gene product.
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PMID:Host- and phage-mediated repair of radiation damage in bacteriophage T4. 456 37