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Hydrogen Bonding Environments in the Photocycle Process around the Flavin Chromophore of the AppA-BLUF domain

発表形態:
原著論文
主要業績:
単著・共著:
発表年月:
2018年09月
DOI:
10.1021/jacs.8b05123
会議属性:
査読:
リンク情報:

日本語フィールド

著者:
Iwata, Tatsuya; Nagai, Takashi; Ito, Shota; Osoegawa, Shinsuke; Iseki, Mineo; Watanabe, Masakatsu; Unno, Masashi; Kitagawa, Shinya; Kandori, Hideki
題名:
Hydrogen Bonding Environments in the Photocycle Process around the Flavin Chromophore of the AppA-BLUF domain
発表情報:
Journal of the American Chemical Society 巻: 140 号: 38 ページ: 11982 - 11991
キーワード:
概要:
Copyright © 2018 American Chemical Society. Three kinds of photochemical reactions are known in flavins as chromophores of photosensor proteins, reflecting the various catalytic reactions of the flavin in flavoenzymes. Sensor of blue light using the flavin FAD (BLUF) domains exhibit a unique photoreaction compared with other flavin-binding photoreceptors in that the chromophore does not change its chemical structure between unphotolyzed and intermediate states. Rather, the hydrogen bonding environment is altered, whereby the conserved Gln and Tyr residues near FAD play a crucial role. One proposal for this behavior is that the conserved Gln changes its chemical structure from a keto to an enol. We applied light-induced difference Fourier transform infrared (FTIR) spectroscopy to AppA-BLUF. The spectra of AppA-BLUF exhibited a different feature upon 15 N-Gln labeling compared with the previously reported spectra from BlrB, a different BLUF domain. The FTIR signals were interpreted from quantum mechanics/molecular mechanics (QM/MM) calculation as the keto-enol tautomerization and rotation of the Gln63 side chain in the AppA-BLUF domain. The former was consistent with the result from BlrB, but the latter was not uniquely determined by the previous study. QM/MM calculation also indicated that the infrared signal shape is influenced depending on whether a Trp side chain forms a hydrogen bond with the Gln side chain. FTIR spectra and QM/MM simulations concluded that Trp104 does not flip out but is maintained in the intermediate state. In contrast, our data revealed that the Trp residue at the corresponding position in BlrB faces outward in both states.
抄録:

英語フィールド

Author:
Iwata, Tatsuya; Nagai, Takashi; Ito, Shota; Osoegawa, Shinsuke; Iseki, Mineo; Watanabe, Masakatsu; Unno, Masashi; Kitagawa, Shinya; Kandori, Hideki
Title:
Hydrogen Bonding Environments in the Photocycle Process around the Flavin Chromophore of the AppA-BLUF domain
Announcement information:
Journal of the American Chemical Society Vol: 140 Issue: 38 Page: 11982 - 11991
An abstract:
Copyright © 2018 American Chemical Society. Three kinds of photochemical reactions are known in flavins as chromophores of photosensor proteins, reflecting the various catalytic reactions of the flavin in flavoenzymes. Sensor of blue light using the flavin FAD (BLUF) domains exhibit a unique photoreaction compared with other flavin-binding photoreceptors in that the chromophore does not change its chemical structure between unphotolyzed and intermediate states. Rather, the hydrogen bonding environment is altered, whereby the conserved Gln and Tyr residues near FAD play a crucial role. One proposal for this behavior is that the conserved Gln changes its chemical structure from a keto to an enol. We applied light-induced difference Fourier transform infrared (FTIR) spectroscopy to AppA-BLUF. The spectra of AppA-BLUF exhibited a different feature upon 15 N-Gln labeling compared with the previously reported spectra from BlrB, a different BLUF domain. The FTIR signals were interpreted from quantum mechanics/molecular mechanics (QM/MM) calculation as the keto-enol tautomerization and rotation of the Gln63 side chain in the AppA-BLUF domain. The former was consistent with the result from BlrB, but the latter was not uniquely determined by the previous study. QM/MM calculation also indicated that the infrared signal shape is influenced depending on whether a Trp side chain forms a hydrogen bond with the Gln side chain. FTIR spectra and QM/MM simulations concluded that Trp104 does not flip out but is maintained in the intermediate state. In contrast, our data revealed that the Trp residue at the corresponding position in BlrB faces outward in both states.


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