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The ChroP Approach Combines ChIP and Mass Spectrometry to Dissect Locus-specific Proteomic Landscapes of Chromatin
Published on: April 11, 2014
Direct Readout of Multivalent Chromatin Reader-Nucleosome Interactions by Nucleosome Mass Spectrometry
Alexander S Lee1,2, Nickolas P Fisher1, Matthew R Marunde3
1Departments of Chemistry and Molecular Biosciences, the Chemistry of Life Processes Institute, and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, United States.
Nucleosome Mass Spectrometry (Nuc-MS) analyzes chromatin-associated protein (CAP) binding to nucleosomes. This method reveals how proteins like BRD4 and DNMT3A interact with specific histone modifications, advancing epigenome regulation studies.
Area of Science:
- Epigenetics and Chromatin Biology
- Mass Spectrometry
- Proteomics
Background:
- Histone post-translational modifications (PTMs) recruit chromatin-associated proteins (CAPs) for epigenome regulation.
- Studying CAP:PTM interactions with histone peptides doesn't fully capture multisite binding on nucleosomes.
Purpose of the Study:
- To develop and apply Nucleosome Mass Spectrometry (Nuc-MS) for analyzing CAP:nucleosome (CAP:nuc) complexes.
- To characterize the binding preferences of various CAPs to specific histone proteoforms on intact nucleosomes.
Main Methods:
- Nucleosome Mass Spectrometry (Nuc-MS): A native Top-Down MS approach for controlled disassembly and proteoform analysis of CAP:nuc complexes.
- Analysis of BPTF, BRD4, DNMT3A-MPP8, and PtSHL engagement with defined and endogenous nucleosomes.
Main Results:
- BPTF tandem reader binds synergistically to multiple PTMs on defined nucleosomes.
- BRD4 favors di- and triacetylated histone H4 proteoforms.
- DNMT3A-MPP8 and PtSHL identify distinct hypermethylated H3 proteoforms, with PtSHL revealing a novel *cis*-combinatorial bivalent histone signature.
Conclusions:
- Nuc-MS directly characterizes CAP:nuc complex composition, identifying nucleoforms that drive binding.
- This method provides crucial insights into the molecular basis of epigenome regulation.
- Identifies primary candidates for further biochemical, structural, and genomic studies.
