Structure of p300 bound to MEF2 on DNA reveals a mechanism of enhanceosome assembly

Abstract

Transcription co-activators CBP and p300 are recruited by sequence-specific transcription factors to specific genomic loci to control gene expression. A highly conserved domain in CBP/p300, the TAZ2 domain, mediates direct interaction with a variety of transcription factors including the myocyte enhancer factor 2 (MEF2). Here we report the crystal structure of a ternary complex of the p300 TAZ2 domain bound to MEF2 on DNA at 2.2Å resolution. The structure reveals three MEF2:DNA complexes binding to different sites of the TAZ2 domain. Using structure-guided mutations and a mammalian two-hybrid assay, we show that all three interfaces contribute to the binding of MEF2 to p300, suggesting that p300 may use one of the three interfaces to interact with MEF2 in different cellular contexts and that one p300 can bind three MEF2:DNA complexes simultaneously. These studies, together with previously characterized TAZ2 complexes bound to different transcription factors, demonstrate the potency and versatility of TAZ2 in protein–protein interactions. Our results also support a model wherein p300 promotes the assembly of a higher-order enhanceosome by simultaneous interactions with multiple DNA-bound transcription factors.

Structural Basis for the Oligomerization of the MADS Domain Transcription Factor SEPALLATA3 in Arabidopsis

“…Structural data are available for the M domain of the mammalian proteins Myocyte-specific enhancer factor 2A (MEF2A) (Perry et al, 2009;Wu et al, 2010;He et al, 2011) and serum response factor (SRF) (Pellegrini et al, 1995;Hassler and Richmond, 2001;Mo et al, 2001) and the fungal protein Minichromosome maintenance protein 1 (MCM1) (Tan and Richmond, 1998), which are all obligate dimers. Based on homology to the structures of MEF2A and SRF M domains (sequence identity of 58 and 47%, respectively, over residues 1 to 58), composite structures of SEP3 encompassing the MIK domains were modeled ( Figure 6).…”

“…Based on homology to the structures of MEF2A and SRF M domains (sequence identity of 58 and 47%, respectively, over residues 1 to 58), composite structures of SEP3 encompassing the MIK domains were modeled ( Figure 6). The available structural data for the MADS TFs includes residues C-terminal to the M domain, the MEF domain (for MEF2A, residues 60 to 89) (He et al, 2011), and the SAM (SRF/Arg80/MCM1) domain (for SRF, residues 198 to 227) (Pellegrini et al, 1995). The I domain present in SEP3 bears little sequence similarity to the MEF or SAM domains, but these domains have approximately the same number of amino acids as the I domain and, in the case of the MEF domain, are intrinsically folded into the M domain.…”

Integration of ChIP-seq and machine learning reveals enhancers and a predictive regulatory sequence vocabulary in melanocytes

“…Though the molecular mechanisms by which enhancers function are not fully understood, it is generally accepted that they are composed of short sequence motifs that bind transcription factors (TFs) (Noonan and McCallion 2010). These TFs recruit transcriptional coactivators such as EP300, CREBBP, and members of the Mediator complex (Panne et al 2007;He et al 2011b), and this enhancer-bound complex of TFs and coactivators then mediates an increase in the expression of a target gene at least in part through direct interaction with the basal transcriptional machinery present at the gene's promoter (Ong and Corces 2011;Chepelev et al 2012). Epigenetic modifications are also thought to play a significant role in enhancer function, as it is well established that histones in the vicinity of enhancers bear characteristic modifications, including H3K4me1 (Heintzman et al 2007(Heintzman et al , 2009) and H3K27Ac (Creyghton et al 2010).…”

Reversal of pathological cardiac hypertrophy via the MEF2-coregulator interface

“…To dynamically modulate MEF2 acetylation, we exploited a series of molecules derived from BML-210, a pimeloylanilide o-aminoanilide (PAOA) compound, that were developed to bind the MADS-box/MEF2S domain of MEF2 competitively with p300 and HDAC4 on the MEF2 MADS domain (38)(39)(40)(41)(42) (Figure 1, C and D). BML-210 and its analogs were originally described as HDAC inhibitors, but have properties that are not reproduced by class I and II HDAC inhibitors such as TSA and SAHA (43), including the ability to block MEF2-dependent transcription by Figure 1.…”

“…The acetylation state of MEF2 is determined by dynamic interactions with coregulators that have either intrinsic or associated acetylation or deacetylation activities, including p300, class IIa HDACs, and cabin1, which share a common cofactor binding site on the MADS-box/MEF2S domain of MEF2 (38,39,41,42). Our data indicate that by binding to this site, 8MI locks MEF2 in a deacetylated state, through a mechanism that depletes the cell of p300 and disrupts activation-induced nuclear export of class IIa HDACs.…”