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

He J, Ye J, Cai Y, Riquelme C, Liu JO, Liu X, Han A, Chen L - Nucleic Acids Res. (2011)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: MOE Key Laboratory for Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China.

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.

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Related in: MedlinePlus

Protein–protein interactions at interfaces II and III. (A) The interaction network at Interface II. (B) Interactions at Interface III viewed from the side of helix α1. (C) Interactions at Interface III viewed from the side of helix α3.
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Figure 4: Protein–protein interactions at interfaces II and III. (A) The interaction network at Interface II. (B) Interactions at Interface III viewed from the side of helix α1. (C) Interactions at Interface III viewed from the side of helix α3.

Mentions: Interface II is formed between helix α1 and the first zinc loop of the TAZ2 domain and a second MEF2 dimer. Here, helix α1 of the TAZ2 domain lies above the two H2 helices of the MEF2 dimer at a cross angle of ∼60° (Supplementary Figure S3). The interface is composed of two separated foci of binding interactions; the first being between the N-terminal part of the TAZ2 α1 helix and helix H2 of one MEF2 monomer (Figure 4A). Met1725 and Leu1733 of p300 and Leu67 of MEF2 form a central hydrophobic patch that is surrounded by a number of electrostatic and hydrogen bond interactions, including salt bridges between Arg1737 and Asp63 and between Arg1732 and Glu71. At the second binding site of IF-II, the C-terminal part of TAZ2 α1 helix and part of the first zinc loop interact with helix H2 of the other MEF2 monomer. Leu1755 of p300 and Leu67 of MEF2 form the hydrophobic core. Leu67 also makes van der Waals contacts with Gln1740 and His1744, while Glu71 makes hydrogen bonds with the main chain and side chain of Ser1757. The side chain of Arg1737 and Pro1756 also make van der Waals contacts with Thr70 and Glu71, respectively.Figure 4.


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

He J, Ye J, Cai Y, Riquelme C, Liu JO, Liu X, Han A, Chen L - Nucleic Acids Res. (2011)

Protein–protein interactions at interfaces II and III. (A) The interaction network at Interface II. (B) Interactions at Interface III viewed from the side of helix α1. (C) Interactions at Interface III viewed from the side of helix α3.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105382&req=5

Figure 4: Protein–protein interactions at interfaces II and III. (A) The interaction network at Interface II. (B) Interactions at Interface III viewed from the side of helix α1. (C) Interactions at Interface III viewed from the side of helix α3.
Mentions: Interface II is formed between helix α1 and the first zinc loop of the TAZ2 domain and a second MEF2 dimer. Here, helix α1 of the TAZ2 domain lies above the two H2 helices of the MEF2 dimer at a cross angle of ∼60° (Supplementary Figure S3). The interface is composed of two separated foci of binding interactions; the first being between the N-terminal part of the TAZ2 α1 helix and helix H2 of one MEF2 monomer (Figure 4A). Met1725 and Leu1733 of p300 and Leu67 of MEF2 form a central hydrophobic patch that is surrounded by a number of electrostatic and hydrogen bond interactions, including salt bridges between Arg1737 and Asp63 and between Arg1732 and Glu71. At the second binding site of IF-II, the C-terminal part of TAZ2 α1 helix and part of the first zinc loop interact with helix H2 of the other MEF2 monomer. Leu1755 of p300 and Leu67 of MEF2 form the hydrophobic core. Leu67 also makes van der Waals contacts with Gln1740 and His1744, while Glu71 makes hydrogen bonds with the main chain and side chain of Ser1757. The side chain of Arg1737 and Pro1756 also make van der Waals contacts with Thr70 and Glu71, respectively.Figure 4.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: MOE Key Laboratory for Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China.

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.

Show MeSH
Related in: MedlinePlus