Fig. 3: The C-terminus of SIRT6 stabilizes the high-affinity binding site.
From: Multivalent interactions drive nucleosome binding and efficient chromatin deacetylation by SIRT6
a Schematic of known SIRT6 domains accompanied with a bioinformatic prediction of protein disorder (MetaPrDos) below. The C-terminal domain (CTD) starts at residue 272 and is predicted to be unstructured. b EMSA comparison of NCP binding between 100 nM SIRT6 and 500 nM C-terminally truncated SIRT6 variants. The 1:1 SIRT6:nucleosome complex is undetectable in native gels when the CTD is truncated, even at lower protein concentrations (Supplementary Fig. 4b). The image is representative of three independent experiments. c As a result, SIRT6(1–292) and SIRT6(1–301) associates with nucleosomes with an order of magnitude weaker affinity. The KDs were calculated with a ligand-depleted equation from titration of SIRT6(1–292) or SIRT6(1–301) to 50 nM NCP. Data are presented as mean ± s.d. from three independent experiments. d The weaker binding site on nucleosomes (KD(Low)) does not require the CTD. The high affinity site on nucleosomes was saturated with 10 nM SIRT6, then increasing concentrations of SIRT6(1–292) was added to bind the available site. Although the formation of the fully formed 2:1 complex is still apparent, it migrates too close to the 1:1 band to accurately quantify. Thus, fraction bound was instead calculated by subtracting the fraction of free nucleosomes still present. Data are presented as mean ± s.d. from three independent experiments. Source data are provided as a source data file.
