Fig. 4: Role of the N-terminal domain in nucleosome binding and deacetylation.

a EMSA of unmodified nucleosomes with wild-type SIRT7 and nucleosome-binding domain mutants. See Supplementary Fig. 12A for replicate gels. b Quantification of SIRT7:nucleosome complex formation with unmodified nucleosomes and mutants as indicated. Error bars represent mean ± SD (n = 4) of distinct samples. Statistical analysis: unpaired t tests, two-tailed, ns: p > 0.05. c SIRT7 wild type and mutant activity on H3K18ac and H3K36ac nucleosomes measured by western blot. SIRT7 concentration was 50 nM and 3 nM, respectively. d Quantification of nucleosome deacetylation normalized to H3 loading, at 50 nM SIRT7 for H3K18ac and 3 nM SIRT7 for H3K36ac. Error bars represent mean ± SD (n = 4‒11, as shown) of distinct samples. Statistical analysis: unpaired t tests, two-tailed, ns: p > 0.05. e Inhibitory effect of free DNA (187 bp) on SIRT7 activity, measured by western blot, and quantification of the effect of 81 equivalents of DNA, normalized to H3 loading. See Supplementary Fig. 12B for complete titration. Error bars represent mean ± SD (n = 4 or 5) of distinct samples. Statistical analysis: unpaired t tests, two-tailed, ns: p > 0.05. f 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 ≥ 4 distinct experiments, and 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, p(H3K18ac) = 2 · 10⁻¹¹. See Supplementary Fig. 13 for SIRT7 western blots, representative microscopy images, and control H4K16ac quantification. Source data are provided as a Source Data file.