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Updated: Jul 6, 2025
Promoter Capture Hi-C: High-resolution, Genome-wide Profiling of Promoter Interactions
Published on: June 28, 2018
p300 is an obligate integrator of combinatorial transcription factor inputs
John J Ferrie1, Jonathan P Karr2, Thomas G W Graham1
1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
Abstract:
Transcription coactivators are proteins or protein complexes that mediate transcription factor (TF) function. However, they lack DNA-binding capacity, prompting the question of how they engage target loci. Three non-exclusive hypotheses have been posited: coactivators are recruited by complexing with TFs, by binding histones through epigenetic reader domains, or by partitioning into condensates through their extensive intrinsically disordered regions. Using p300 as a prototypical coactivator, we systematically mutated its annotated domains and show by single-molecule tracking in live U2OS cells that coactivator-chromatin binding depends entirely on combinatorial binding of multiple TF-interaction domains. Furthermore, we demonstrate that acetyltransferase activity opposes p300-chromatin association and that the N-terminal TF-interaction domains regulate that activity. Single TF-interaction domains are insufficient for chromatin binding and regulation of catalytic activity, implying a principle that we speculate could broadly apply to eukaryotic gene regulation: a TF must act in coordination with other TFs to recruit coactivator activity.
Insights
Transcription coactivators like p300 bind chromatin via multiple transcription factor (TF) interaction domains. Their catalytic activity is regulated by these domains, suggesting TFs coordinate to recruit coactivator function.
Area of Science:
- Molecular Biology
- Epigenetics
- Gene Regulation
Background:
- Transcription coactivators are essential for gene expression but lack DNA-binding domains.
- Their recruitment to specific genomic loci remains poorly understood.
- Hypotheses include transcription factor (TF) complexing, histone binding, or phase separation.
Purpose of the Study:
- To elucidate the mechanism by which transcription coactivators, using p300 as a model, associate with chromatin.
- To investigate the role of p300 domains in chromatin binding and catalytic activity regulation.
Main Methods:
- Systematic domain mutagenesis of the p300 coactivator.
- Single-molecule tracking in live U2OS cells.
- Analysis of coactivator-chromatin association and acetyltransferase activity.
Main Results:
- Coactivator-chromatin binding is dependent on the combinatorial interaction of multiple TF-binding domains.
- p300's acetyltransferase activity inhibits its own chromatin association.
- N-terminal TF-interaction domains regulate p300's catalytic activity.
Conclusions:
- Multiple TF interactions are necessary for coactivator chromatin engagement.
- TF-interaction domains control coactivator catalytic function, impacting chromatin association.
- Eukaryotic gene regulation may require coordinated TF action for coactivator recruitment.
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