Fig. 4. Excess Mn disrupts CoQ-mediated electron transport, while respiratory chain complexes remain intact.

a Schematic depicting the electron flow and the Q cycle in the respiratory chain. IMS = intermembrane space; IMM = inner mitochondrial membrane. b Blue‐native gel electrophoresis and immunoblots of respiratory supercomplexes in mitochondria isolated from WT and ∆pmr1 cells. Blots were decorated with antibodies against CIV (Cox2 and Cox5). Representative images of n = 3 are shown. c–i Spectrophotometric analysis of electron flow through the respiratory chain in mitoplasts obtained from mitochondria isolated from the indicated conditions (WT cells with or without 5 mM MnCl₂ or ∆pmr1 cells). Cells were grown on glucose for 24 h. CIV activity assessed through oxidation of exogenous reduced cytochrome c (cyt c) (c, e), NADH/succinate-independent CIII activity with exogenous decylubiquinol and oxidized cyt c (d, f), succinate-driven CIII activity with and without supplementation of decylubiquinone (dCoQ) (g) and NADH-driven CIII activity with and without supplementation of dCoQ (h, i) are shown. Means ± SEM, n = 3. j Spectrophotometric analysis of NADH-driven CIII activity in mitoplasts obtained from WT and ∆pmr1 cells overexpressing Coq7 or harboring the vector control. Means ± SEM, n = 3. Details for statistical analysis (Supplementary Table 9) and source data are provided.