Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I.

Autor: Uno S; Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan., Masuya T; Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan., Zdorevskyi O; Department of Physics, University of Helsinki, Helsinki, Finland., Ikunishi R; Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan., Shinzawa-Itoh K; Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo, Japan., Lasham J; Department of Physics, University of Helsinki, Helsinki, Finland., Sharma V; Department of Physics, University of Helsinki, Helsinki, Finland; Institute of Biotechnology, University of Helsinki, Helsinki, Finland., Murai M; Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan., Miyoshi H; Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan. Electronic address: miyoshi.hideto.8e@kyoto-u.ac.jp.
Jazyk: angličtina
Zdroj: The Journal of biological chemistry [J Biol Chem] 2022 Jul; Vol. 298 (7), pp. 102075. Date of Electronic Publication: 2022 May 25.
DOI: 10.1016/j.jbc.2022.102075
Abstrakt: The ubiquinone (UQ) reduction step catalyzed by NADH-UQ oxidoreductase (mitochondrial respiratory complex I) is key to triggering proton translocation across the inner mitochondrial membrane. Structural studies have identified a long, narrow, UQ-accessing tunnel within the enzyme. We previously demonstrated that synthetic oversized UQs, which are unlikely to transit this narrow tunnel, are catalytically reduced by native complex I embedded in submitochondrial particles but not by the isolated enzyme. To explain this contradiction, we hypothesized that access of oversized UQs to the reaction site is obstructed in the isolated enzyme because their access route is altered following detergent solubilization from the inner mitochondrial membrane. In the present study, we investigated this using two pairs of photoreactive UQs (pUQ m-1 /pUQ p-1 and pUQ m-2 /pUQ p-2 ), with each pair having the same chemical properties except for a ∼1.0 Å difference in side-chain widths. Despite this subtle difference, reduction of the wider pUQs by the isolated complex was significantly slower than of the narrower pUQs, but both were similarly reduced by the native enzyme. In addition, photoaffinity-labeling experiments using the four [ 125 I]pUQs demonstrated that their side chains predominantly label the ND1 subunit with both enzymes but at different regions around the tunnel. Finally, we show that the suppressive effects of different types of inhibitors on the labeling significantly changed depending on [ 125 I]pUQs used, indicating that [ 125 I]pUQs and these inhibitors do not necessarily share a common binding cavity. Altogether, we conclude that the reaction behaviors of pUQs cannot be simply explained by the canonical UQ tunnel model.
Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article.
(Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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