Fig. 5: Loops flanking SIRT7 catalytic domain control substrate selectivity.

a Summary of mutated catalytic domain loops. b SIRT7 wild type and mutant activity on H3K18ac and H3K36ac nucleosomes measured by western blot. SIRT7 concentration was 50 nM and 3 nM, respectively. c Quantification of nucleosome deacetylation normalized to H3 loading, at 50 nM SIRT7 for H3K18ac (top) and 3 nM SIRT7 for H3K36ac (bottom). See Supplementary Fig. 12D for data on helix α3 mutant K72A, R73A, R74A. Error bars represent mean ± SD (n = 4‒11, as shown) of distinct samples. Statistical analysis: unpaired t tests, two-tailed, ns: p > 0.05, p(K272A, K275A, K276A) = 2 · 10⁻⁸. d Quantification of wild type and K272A, K275A, K276A mutant activity at 50 nM SIRT7 concentration. Error bars represent mean ± SD (n = 4‒11, as shown) of distinct samples. Statistical analysis: unpaired t tests, two-tailed, ns: p > 0.05, p(K272A, K275A, K276A) = 2 × 10⁻⁸. e Violin plot (truncated) of H3K18ac and H3K36ac levels in HEK293F SIRT7^−/− cells²⁷ upon transient transfection with SIRT7-mCherry constructs as indicated, measured by immunofluorescence. Internal lines represent median and quartile values of n ≥ 3 distinct experiments, and a light background line indicates median value for WT SIRT7. Statistical analysis: Kruskal–Wallis and Dunn’s multiple comparisons tests, non-parametric two-tailed, ns: p > 0.05. See Supplementary Fig. 13 for SIRT7 western blots, representative microscopy images, and control H4K16ac quantification. Source data are provided as a Source Data file.