1994 Fiscal Year Final Research Report Summary
(6-4) photoproduct photoreactivating enzyme in Drosophila melanogaster
| Project/Area Number |
05808049
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
環境影響評価(含放射線生物学)
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| Research Institution | Osaka University |
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Principal Investigator |
TODO Takashi Osaka University, Radiation Biology, Research Assoc, 医学部, 助手 (90163948)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Ultraviolet Light / DNA damage / (6-4) photoproduct / Phtoreactivating enzyme |
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| Research Abstract |
DNA photolyase catalyzes the light-dependent repair of cis, syn-cyclobutane dipyrimidines (pyrimidine dimers). We cloned cDNA encoding the Drosophila photolyase gene ; it contained an open reading frame to encode a 61,483 Dalton protein. The product of the cDNA made in E.coli cells showed activity to photorepair pyrimidine dimers in vitro. The cloned cDNA hybridized to the band 44C-D of the polytene chromosome, genetically mapped site of photorepair-deficient (phr-) gene, and also to DNA of the phr-gene by the southern blot analysis ; the latter revealed that the phr-mutant gene has DNA rearrangement (s) within it. These results indicate that the cloned cDNA corresponds to the phr gene of Drosophila. We found that activity of photolyase of Drosophila is very high in the embryo-about 6700 molecules/cell-and also in the adult ovary whereas mRNA of photolyase is abundent only in the adult ovary, an indication that the Drosophila photolyase gene is a maternal gene. We have also purified Drosophila photolyase from embryo. A molecular weight of 62,000 was estimated from SDS-gel electrophoresis. The action spectrum of the purified photolyase for photoreactivation of UV-irradiated plasmid DNA showed a single, sharp maximum around 440 nm. The predicted amino-acid sequence of Drosophila photolyase shares an extensive homology with that of a goldfish Carassius auratus photolyase but only limited homologies with those of microorganisms.
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