Single Hydrogen Bond Donation from Flavin N5 to Proximal Asparagine Ensures FAD Reduction in DNA Photolyase

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• 作者：I M. Mahaputra Wijaya ; Tatiana Domratcheva ; Tatsuya Iwata ; Elizabeth D. Getzoff ; Hideki Kandori
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：138
• 期：13
• 页码：4368-4376
• 全文大小：466K
• ISSN：1520-5126

文摘

The spread of the absorbance of the stable FADH^• radical (300–700 nm) allows CPD photolyase to highly efficiently form FADH^–, making it functional for DNA repair. In this study, FTIR spectroscopy detected a strong hydrogen bond, from FAD N₅–H to the carbonyl group of the Asn378 side chain, that is modulated by the redox state of FAD. The observed characteristic frequency shifts were reproduced in quantum-mechanical models of the flavin binding site, which were then employed to elucidate redox tuning governed by Asn378. We demonstrate that enhanced hydrogen bonding of the Asn378 side chain with the FADH^• radical increases thermodynamic stabilization of the radical state, and further ensures kinetic stabilization and accumulation of the fully reduced FADH^– state.