1. ND3 Cys39 in complex I is exposed during mitochondrial respiration
- Author
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Burger, Nils, James, Andrew M., Mulvey, John F., Hoogewijs, Kurt, Ding, Shujing, Fearnley, Ian M., Loureiro-López, Marta, Norman, Abigail A.I., Arndt, Sabine, Mottahedin, Amin, Sauchanka, Olga, Hartley, Richard C., Krieg, Thomas, and Murphy, Michael P.
- Subjects
food and beverages - Abstract
Mammalian complex I can adopt catalytically active (A-) or deactive (D-) states. A defining feature of the reversible transition between these two defined states is thought to be exposure of the ND3 subunit Cys39 residue in the D-state and its occlusion in the A-state. As the catalytic A/D transition is important in health and disease, we set out to quantify it by measuring Cys39 exposure using isotopic labeling and mass spectrometry, in parallel with complex I NADH/CoQ oxidoreductase activity. To our surprise, we found significant Cys39 exposure during NADH/CoQ oxidoreductase activity. Furthermore, this activity was unaffected if Cys39 alkylation occurred during complex I-linked respiration. In contrast, alkylation of catalytically inactive complex I irreversibly blocked the reactivation of NADH/CoQ oxidoreductase activity by NADH. Thus, Cys39 of ND3 is exposed in complex I during mitochondrial respiration, with significant implications for our understanding of the A/D transition and the mechanism of complex I.
- Published
- 2022