Figure 1. FXN-KO cardiac mitochondria have protein hyperacetylation, redox imbalance, and altered NAD⁺ homeostasis.

(A) Difference in mitochondrial protein acetylation relative occupancy sites (i.e., acetyl peptides quantification corrected for change in protein abundance) between WT and FXN-KO at 5, 8, and 13 weeks of age. Black represents statistically significant (P_adjusted ≤ 0.05) acetyl sites with FCs above 2- or below –2-fold; dark gray represents FCs in between; and light gray represents acetyl sites with no statistically significant FC. (B) Proteomic measurements of OXPHOS complex I subunit levels in WT and FXN-KO heart mitochondria at 5, 8, and 13 weeks of age. Bar line represents sample mean. Subunits shown are statistically significant from respective WT (at 8 and 13 weeks). (C–D) Proteomic measurements of NAD⁺ biosynthesis proteins NAMPT (C) and NMNAT3 (D) in WT and FXN-KO heart mitochondria at 5, 8, and 13 weeks of age. Bar line represents sample mean. (E) Statistically significant acetyl-lysine sites in common between the SIRT3-KO whole hearts (green; ^ from ref. 28); and FXN-KO heart mitochondria at 5, 8, and 13 weeks of age (shades of red). Purple and pink shading represents 1 SD from the mean of the bottom and top, respectively, 25% SIRT3-KO sites. (F) Schematic summarizing shifts in the mitochondrial NAD⁺ metabolome in the FXN-KO heart. *P < 0.05, difference from respective WT values at each age group by Student’s t test and Benjamini-Hochberg FDR correction; n = 3 mice per age group per genotype. W: WT, F: FXN-KO and S: SIRT3-KO.