1997 Fiscal Year Final Research Report Summary
Crystallographic Study of Molecular Mechanism of DNA Repair by Photolyase
| Project/Area Number |
08458208
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
MIKI Kunio Graduate School of Science, Kyoto Univ., Professor, 大学院・理学研究科, 教授 (10116105)
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| Co-Investigator(Kenkyū-buntansha) |
KITADOKORO Kengo Faculty of Science, Kyoto Univ., Res.Asooc., 理学部, 助手 (60283587)
KITA Akiko Graduate School of Science, Kyoto Univ., Res.Asooc., 大学院・理学研究科, 助手 (70273430)
HIGUCHI Yoshiki Graduate School of Science, Kyoto Univ., Assoc.Prof., 大学院・理学研究科, 助教授 (90183574)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Photolyase / DNA Repair / 3D-Structure / X-ray Crystallography / Structural Biology |
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| Research Abstract |
Photolyases are 50 to 70 kDa single chain proteins containing two different chromophoric cofactors in equimolar amounts. Photoreactivation comprises several steps : damage recognition and binding of photolyase to DNA,photon absorption, interchromophoric energy transfer and electron transfer from chrompophore to DNA,resulting in the reversal of UV-induced pyrimidine dimers into monomers. The catalytic cofactor FAD is essential for the light-dependent repair process. In addition, a second cofactor is present which acts as a light-harvesting chromophore. Two structures are known for the second cofactor, either 8-hydroxy-5-deazaflavin (8-HDF) present in photolyase from e.g.the cyanobacterium, Anacystis nidulans or 5,10-methenyltetrahydro-folic acid (MTHF) found in E.coli photolyase. The crystal structure of A.nidulans photolyase (53,000 Da) was determined at 1.8 resolution from X-ray diffraction data obtained with synchrotron radiation. The refined model, comprising the residues 1 to 475, the two cofactors and 192 water molecules, has an R-factor of 0.197. The structure is composed of an alpha/beta and a helical domain, which provides binding sites for the 8-HDF and FAD chromophores, respectively. The present crystal structure of 8-HDF type photolyase from Anacystis nidulans showed the similarity of the backbone structure with MTHF type E.coli photolyase but completely different binding site of the light-harvesting cofactor. This is a first example that homologous primary and tertiary structures in closely related proteins recognize two different rtpes of cofactors at different binding-sites.
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Research Products
(2 results)
