1999 Fiscal Year Final Research Report Summary
Biochemical properties and molecular evolution of photolyase which reduces threat of solar ultraviolet light.
| Project/Area Number |
09308020
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
IKENAGA Mituo Kyoto University, Radiation Biology Center, Professor, 放射線生物研究センター, 教授 (70025378)
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| Co-Investigator(Kenkyū-buntansha) |
YAGI Takashi Kyoto University, Graduate School of Medicine, Associate Professor, 医学研究科, 助教授 (80182301)
KATO Tomohisa Kyoto University, Radiation Biology Center, Instructor, 放射線生物研究センター, 助手 (50301247)
TODO Takeshi Kyoto University, Radiation Biology Center, Associate Professor, 放射線生物研究センター, 助教授 (90163948)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Solar ultraviolet light / Skin cancer / Pyrimidine dimer / (6-4) photoproduct / DNA photolyase / Human homolog gene / Molecular evolution / Circadian rhythm |
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| Research Abstract |
1. Isolation of (6-4) photolyase genes from different organisms
We have isolated (6-4) photolyase genes from Xenopus laevis, Arabidopsis thaliana and zebra fish, using oligonucleotide primers synthesized on the basis of conserved sequences between (6-4) photolyase of Drosophila and its human homolog.
2. Biochemical properties of (6-4) photolyase
We identified that flavin adenine dinucleotide is a chromophore of Xenopus (6-4) photolyase, and determined its binding and dissociation constants in the enzyme reaction.
3. Expression of marsupial photolyase in humna cells
We expressed an opossum DNA photolyase specific for cyclobutane pyrimidine dimers (CPD) in DNA repair-deficient group A xeroderma pigmentosum (XP-A) cells. Exposure of the cells to visible light elevated survival of UV-irradiated XP-A cells and reduced mutation frequencies of UV-irradiated shuttle vector plasmids replicating in these cells.
4. Molecular evolution of the photolyase family
Class I and II CPD photolyases, (6-4) photolyase, its animal homologue, and blue light photoreceptor constitute a family with respect to amino acid sequence similarity. The phylogenetic analysis suggested that the ancestral gene of the family, i. e., the CPD photolyase gene, had duplicated at least five times before the divergence between eubacteria and eukaryotes, to yield functional diversity of the family.
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