Figure 6: Exploring the mechanism of activation by inositol phosphates.
From: Insights into the activation mechanism of class I HDAC complexes by inositol phosphates
(a) Comparison of the binding of 2-FAM-Ins(1,3,4,5,6)P5 to HDAC3:SMRT and HDAC3 (R265A):SMRT. (b) Measurement of Km and kcat in the presence and absence of InsP6, for HDAC3 (R265A):SMRT. Data for the wild-type HDAC3:SMRT are also shown for comparison (N.B. the data are presented on a different scale from Fig. 4c). (c) Repression assay showing that repression mediated through HDAC3 recruitment by GAL4 – SMRT, is reduced by mutation of R265. (d) Comparison of the effect of various different HDAC inhibitors on the binding of 2-FAM-Ins(1,3,4,5,6)P5 to HDAC3:SMRT. (e) CD denaturation curves of HDAC3:SMRT showing that InsP6 and SAHA both stabilize the complex and have a greater effect when combined. Tm (°C)=melting temperature. Molar ellipticiy was monitored at 222 nm, and melting curves fitted using GraphPad Prism. (f) Close-up view of the H4K16Hx (pink sticks) bound in the active site of HDAC1 (electrostatic surface), InsP6 (purple) is bound in close proximity to the active site at the interface with MTA1 (green cartoon). Residues involved in binding both InsP6 and H4K16Hx are labelled. Error bars indicate±s.e.m. (n=3).
