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NMR basis for interprotein electron transfer gating between cytochrome c and cytochrome c oxidase
| 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) |
| URI: | http://hdl.handle.net/2115/48142 |
| 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)
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Submitter: 石森 浩一郎
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