Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.99.3 (PRE)
 1,923 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of a gene for photolyase in RBCF-1 cells, a line of cultured goldfish cells, is known to be enhanced by fluorescent light. We have now found that H2O2 is another strong inducer of cyclobutane pyrimidine dimer photolyase. Northern blot analysis suggested that regulation by H2O2 occurs at the transcriptional level and the time course of induction of photolyase by H2O2 was similar to that by fluorescent light. Treatment with fluorescent light in the presence of riboflavin, which is known as an endogenous photosensitizer, also enhanced the induction of photolyase. These results suggest the involvement of oxygen stress in the induction of photolyase by fluorescent light. A cell clone with high-level expression of the goldfish gene for photolyase was obtained by transfection with plasmids that expressed the goldfish photolyase in OL32 cells derived from another fish, the medaka (Oryzias latipes). The induction of the medaka gene for photolyase was not affected by the high-level expression of the goldfish gene for this enzyme.
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PMID:Induction of cyclobutane pyrimidine dimer photolyase in cultured fish cells by fluorescent light and oxygen stress. 774 81

We examined DNA repair activities of a mitochondrial lysate derived from Xenopus laevis oocytes. Plasmid DNA, exposed to HCl, H2O2 or UV light, was used as the substrate for the in vitro repair reaction. DNA synthesis in the lysate was stimulated 2-8-fold by such lesions, indicating the presence of excision repair activities. This repair DNA synthesis was not affected by aphidicolin, but was sensitive to N-ethylmaleimide. Thus the mitochondrial DNA polymerase, i.e., pol gamma is indeed involved in the reaction. Actual repair of the depurinated DNA was demonstrated by using the polymerase chain reaction (PCR), where the amount of the amplified DNA fragment increased significantly if the depurinated template was incubated in the lysate prior to the PCR. UV-irradiated DNA, on the other hand, restored its ability as a PCR template only if the repair reaction was carried out under the light. Therefore, in this system, UV-induced damage is repaired mainly by photoreactivation. These results show that mitochondria of Xenopus oocytes possess excision repair as well as photolyase activities, and that the in vitro repair system described here should be useful for further molecular characterization of such DNA repair machinery.
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PMID:Repair of DNA damage in a mitochondrial lysate of Xenopus laevis oocytes. 891 12