Distinct kinetic mechanisms of H3K4 methylation catalyzed by MLL3 and MLL4 core complexes
| Autor: | Yinping Huang, Lijie Zhao, Jun Mencius, Yanjing Li, Shu Quan, Wanting Luo, Yongxin Zheng, Yong Chen |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
MLL
0301 basic medicine Histone H3 Lysine 4 Methyltransferase SET SU(VAR)3–9 E(Z) and TRX Peptide ULP1 ubiquitin-like-specific protease 1 Methylation Biochemistry MLL mixed-lineage leukemia Catalysis Histones 03 medical and health sciences kcat turnover number M4WARD MLL4-WDR5-ASH2L-RBBP5-DPY30 enzyme kinetics Histone methylation Humans enzyme mechanism histone methylation Enzyme kinetics AS activation segment Enhancer Molecular Biology chemistry.chemical_classification IPTG isopropyl 1-thio-β-D-galactopyranoside ABM ASH2L-binding motif epigenetics 030102 biochemistry & molecular biology Histone-Lysine N-Methyltransferase Cell Biology kcat/Km catalytic efficiency DNA-Binding Proteins M3RA MLL3SET-RBBP5AS-ABM-ASH2LSPRY Kinetics 030104 developmental biology Enzyme chemistry Biophysics methyltransferase M4RA MLL4SET-RBBP5AS-ABM-ASH2LSPRY Protein Processing Post-Translational SPRY splA and ryanodine receptor Research Article Protein Binding |
| Zdroj: | The Journal of Biological Chemistry |
| ISSN: | 0021-9258 |
| DOI: | 10.1016/j.jbc.2021.100635 |
| Popis: | The methyltransferases MLL3 and MLL4 primarily catalyze the monomethylation of histone H3 lysine 4 (H3K4) on enhancers to regulate cell-type-specific gene expression and cell fate transition. MLL3 and MLL4 share almost identical binding partners and biochemical activities, but perform specific and nonredundant functions. The features and functions that distinguish MLL3 and MLL4 remain elusive. Here, we characterize the kinetic mechanisms of MLL3 and MLL4 ternary complexes containing the catalytic SET domain from MLL3 or MLL4 (MLL3SET or MLL4SET), the SPRY domain of ASH2L (ASH2LSPRY), and a short fragment of RBBP5 (RBBP5AS-ABM) to search for possible explanations. Steady-state kinetic analyses and inhibition studies reveal that the MLL3 complex catalyzes methylation in a random sequential bi–bi mechanism. In contrast, the MLL4 complex adopts an ordered sequential bi–bi mechanism, in which the cofactor S-adenosylmethionine (AdoMet) binds to the enzyme prior to the H3 peptide, and the methylated H3 peptide dissociates from the enzyme before S-adenosylhomocysteine (AdoHcy) detaches after methylation. Substrate-binding assays using fluorescence polarization (FP) confirm that AdoMet binding is a prerequisite for H3 binding for the MLL4 complex but not for the MLL3 complex. Molecular dynamic simulations reveal that the binding of AdoMet exclusively induces conformational constraints on the AdoMet-binding groove and the H3 substrate-binding pocket of MLL4, therefore stabilizing a specific active conformation to ease entry of the substrate H3. The distinct kinetic mechanisms and conformational plasticities provide important insights into the differential functions of MLL3 and MLL4 and may also guide the development of selective inhibitors targeting MLL3 or MLL4. |
| Databáze: | OpenAIRE |
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