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NMR basis for interprotein electron transfer gating between cytochrome c and cytochrome c oxidase

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Title: NMR basis for interprotein electron transfer gating between cytochrome c and cytochrome c oxidase
Authors: Sakamoto, Koichi Browse this author
Kamiya, Masakatsu Browse this author
Imai, Mizue Browse this author
Shinzawa-Itoh, Kyoko Browse this author
Uchida, Takeshi Browse this author
Kawano, Keiichi Browse this author
Yoshikawa, Shinya Browse this author
Ishimori, Koichiro Browse this author
Keywords: interaction site
ET complex
isotope edited-NMR
unidirectional ET
redox-dependent interaction
Issue Date: 26-Jul-2011
Publisher: National Academy of Sciences
Journal Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 108
Issue: 30
Start Page: 12271
End Page: 12276
Publisher DOI: 10.1073/pnas.1108320108
Abstract: The final interprotein electron transfer (ET) in the mammalian respiratory chain, from cytochrome c (Cyt c) to cytochrome c oxidase (CcO) is investigated by 1H-15N heteronuclear single quantum coherence spectral analysis. The chemical shift perturbation in isotope-labeled Cyt c induced by addition of unlabeled CcO indicates that the hydrophobic heme periphery and adjacent hydrophobic amino acid residues of Cyt c dominantly contribute to the complex formation, whereas charged residues near the hydrophobic core refine the orientation of Cyt c to provide well controlled ET. Upon oxidation of Cyt c, the specific line broadening of N-H signals disappeared and high field 1H chemical shifts of the N-terminal helix were observed, suggesting that the interactions of the N-terminal helix with CcO are reduced by steric constraint in oxidized Cyt c, while the chemical shift perturbations in the C-terminal helix indicate notable interactions of oxidized Cyt c with CcO. These results suggest that the overall affinity of oxidized Cyt c for CcO is significantly, but not very much weaker than that of reduced Cyt c. Thus, electron transfer is gated by dissociation of oxidized Cyt c from CcO, the rate of which is controlled by the affinity of oxidized Cyt c to CcO for providing an appropriate electron transfer rate for the most effective energy coupling. The conformational changes in Lys13 upon CcO binding to oxidized Cyt c, shown by 1H- and 1H, 15N-chemical shifts, are also expected to gate intraprotein ET by a polarity control of heme c environment.
Type: article (author version)
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 石森 浩一郎

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