Design of a fluorescent ligand targeting the S-adenosylmethionine binding site of the histone methyltransferase MLL1.

Abstract

The histone methyltransferase MLL1 has been linked to translocation-associated gene fusion in childhood leukemias and is an attractive drug target. High-throughput biochemical analysis of MLL1 methyltransferase activity requires the production of at least a trimeric complex of MLL1, RbBP5 and WDR5 to elicit robust activity. Production of trimeric and higher order MLL1 complexes in the quantities and reproducibility required for high-throughput screening presents a significant impediment to MLL1 drug discovery efforts. We present here a small molecule fluorescent ligand (FL-NAH, 6) that is able to bind to the S-adenosylmethionine (SAM) binding site of MLL1 in a manner independent of the associated complex members. We have used FL-NAH to develop a fluorescence polarization-based SAM displacement assay in a 384-well format targeting the MLL1 SET domain in the absence of associated complex members. FL-NAH competes with SAM and is displaced from the MLL1 SET domain by other SAM-binding site ligands with Kdisp values similar to the higher-order complexes, but is unaffected by the H3 peptide substrate. This assay enables screening for SAM-competitive MLL1 inhibitors without requiring the use of trimeric or higher order MLL1 complexes, significantly reducing screening time and cost.

• Authors: Yepeng Luan, Levi L Blazer, Hao Hu, Taraneh Hajian, Jing Zhang, Hong Wu, Scott Houliston, Cheryl H Arrowsmith, Masoud Vedadi, Yujun George Zheng
• Journal: Organic & biomolecular chemistry (Org Biomol Chem) Vol. 14 Issue 2 Pg. 631-638 (Jan 14 2016) ISSN: 1477-0539 [Electronic] England
• PMID: 26541578 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Enzyme Inhibitors
• KMT2A protein, human
• Ligands
• Small Molecule Libraries
• Myeloid-Lymphoid Leukemia Protein
• S-Adenosylmethionine
• Histone-Lysine N-Methyltransferase

Topics

• Binding, Competitive (drug effects)
• Dose-Response Relationship, Drug
• Drug Design
• Drug Evaluation, Preclinical (economics, methods)
• Enzyme Inhibitors (chemical synthesis, chemistry, pharmacology)
• Fluorescence
• Histone-Lysine N-Methyltransferase (chemistry, metabolism)
• Humans
• Ligands
• Molecular Structure
• Myeloid-Lymphoid Leukemia Protein (chemistry, metabolism)
• Protein Structure, Tertiary
• S-Adenosylmethionine (metabolism)
• Small Molecule Libraries (chemical synthesis, chemistry, pharmacology)
• Structure-Activity Relationship
• Time Factors