Structure of the MADS-box/MEF2 Domain of MEF2A Bound to DNA and Its Implication for Myocardin Recruitment

Abstract

Myocyte enhancer factor 2 (MEF2) regulates specific gene expression in diverse developmental programs and adaptive responses. MEF2 recognizes DNA and interacts with transcription cofactors through a highly conserved N-terminal domain referred to as the MADS-box/MEF2 domain. Here we present the crystal structure of the MADS-box/MEF2 domain of MEF2A bound to DNA. In contrast to previous structural studies showing that the MEF2 domain of MEF2A is partially unstructured, the present study reveals that the MEF2 domain participates with the MADS-box in both dimerization and DNA binding as a single domain. The sequence divergence at and immediately following the C-terminal end of the MEF2 domain may allow different MEF2 dimers to recognize different DNA sequences in the flanking regions. The current structure also suggests that the ligand-binding pocket previously observed in the Cabin1-MEF2B-DNA complex and the HDAC9 (histone deacetylase 9)-MEF2B-DNA complex is not induced by cofactor binding but rather preformed by intrinsic folding. However, the structure of the ligand-binding pocket does undergo subtle but significant conformational changes upon cofactor binding. On the basis of these observations, we generated a homology model of MEF2 bound to a myocardin family protein, MASTR, that acts as a potent coactivator of MEF2-dependent gene expression. The model shows excellent shape and chemical complementarity at the binding interface and is consistent with existing mutagenesis data. The apo structure presented here can also serve as a target for virtual screening and soaking studies of small molecules that can modulate the function of MEF2 as research tools and therapeutic leads.

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).…”

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.…”

SVP-like MADS-box protein from Carya cathayensis forms higher-order complexes

“…The dimer model revealed byY2H assays proves the existence of interaction between the tested partners, but it is uncertain if the dimers are not higher-order complexes containing many copies of the polypeptides. Crystal structures of MADS-domain in complex with CArG-box DNA support the domain dimerization, but the full length protein may be multimers since the crystallized proteins were C-terminus truncated (Santelli and Richmond, 2000;Wu et al, 2010).…”