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Updated: May 6, 2026
Analysis of Histone Antibody Specificity with Peptide Microarrays
Published on: August 1, 2017
Solution NMR structure and histone binding of the PHD domain of human MLL5
Alexander Lemak1, Adelinda Yee, Hong Wu
1Northeast Structural Genomics Consortium and Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada.
Abstract:
Mixed Lineage Leukemia 5 (MLL5) is a histone methyltransferase that plays a key role in hematopoiesis, spermatogenesis and cell cycle progression. In addition to its catalytic domain, MLL5 contains a PHD finger domain, a protein module that is often involved in binding to the N-terminus of histone H3. Here we report the NMR solution structure of the MLL5 PHD domain showing a variant of the canonical PHD fold that combines conserved H3 binding features from several classes of other PHD domains (including an aromatic cage) along with a novel C-terminal α-helix, not previously seen. We further demonstrate that the PHD domain binds with similar affinity to histone H3 tail peptides di- and tri-methylated at lysine 4 (H3K4me2 and H3K4me3), the former being the putative product of the MLL5 catalytic reaction. This work establishes the PHD domain of MLL5 as a bone fide 'reader' domain of H3K4 methyl marks suggesting that it may guide the spreading or further methylation of this site on chromatin.
Insights
Mixed Lineage Leukemia 5 (MLL5) protein
Area of Science:
- Biochemistry
- Molecular Biology
- Epigenetics
Background:
- Mixed Lineage Leukemia 5 (MLL5) is a histone methyltransferase crucial for hematopoiesis, spermatogenesis, and cell cycle regulation.
- MLL5 possesses a PHD finger domain, known for binding histone H3 N-termini.
Purpose of the Study:
- To determine the NMR solution structure of the MLL5 PHD domain.
- To investigate the binding interactions of the MLL5 PHD domain with histone H3 peptides.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was used to determine the solution structure.
- Histone H3 tail peptides with specific methylation states (H3K4me2, H3K4me3) were synthesized and used in binding assays.
Main Results:
- The MLL5 PHD domain adopts a variant PHD fold with conserved H3-binding features and a novel C-terminal α-helix.
- The domain exhibits similar binding affinities for H3K4me2 and H3K4me3 peptides.
- H3K4me2 is the likely product of MLL5's catalytic activity.
Conclusions:
- The MLL5 PHD domain functions as a 'reader' of H3K4 methylation marks.
- This interaction suggests a role for the MLL5 PHD domain in guiding chromatin methylation dynamics.
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