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Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I

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 demo...

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Autores principales: Uno, Shinpei, Masuya, Takahiro, Zdorevskyi, Oleksii, Ikunishi, Ryo, Shinzawa-Itoh, Kyoko, Lasham, Jonathan, Sharma, Vivek, Murai, Masatoshi, Miyoshi, Hideto
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9243180/
https://www.ncbi.nlm.nih.gov/pubmed/35643318
http://dx.doi.org/10.1016/j.jbc.2022.102075
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author Uno, Shinpei
Masuya, Takahiro
Zdorevskyi, Oleksii
Ikunishi, Ryo
Shinzawa-Itoh, Kyoko
Lasham, Jonathan
Sharma, Vivek
Murai, Masatoshi
Miyoshi, Hideto
author_facet Uno, Shinpei
Masuya, Takahiro
Zdorevskyi, Oleksii
Ikunishi, Ryo
Shinzawa-Itoh, Kyoko
Lasham, Jonathan
Sharma, Vivek
Murai, Masatoshi
Miyoshi, Hideto
author_sort Uno, Shinpei
collection PubMed
description 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.
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spelling pubmed-92431802022-07-01 Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I Uno, Shinpei Masuya, Takahiro Zdorevskyi, Oleksii Ikunishi, Ryo Shinzawa-Itoh, Kyoko Lasham, Jonathan Sharma, Vivek Murai, Masatoshi Miyoshi, Hideto J Biol Chem Research Article 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. American Society for Biochemistry and Molecular Biology 2022-05-25 /pmc/articles/PMC9243180/ /pubmed/35643318 http://dx.doi.org/10.1016/j.jbc.2022.102075 Text en © 2022 The Authors https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Research Article
Uno, Shinpei
Masuya, Takahiro
Zdorevskyi, Oleksii
Ikunishi, Ryo
Shinzawa-Itoh, Kyoko
Lasham, Jonathan
Sharma, Vivek
Murai, Masatoshi
Miyoshi, Hideto
Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I
title Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I
title_full Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I
title_fullStr Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I
title_full_unstemmed Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I
title_short Diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex I
title_sort diverse reaction behaviors of artificial ubiquinones in mitochondrial respiratory complex i
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9243180/
https://www.ncbi.nlm.nih.gov/pubmed/35643318
http://dx.doi.org/10.1016/j.jbc.2022.102075
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