A non-active site SET domain surface crucial for the interaction of MLL1 and the RbBP5-ASH2L heterodimer within MLL family core complexes.

TitleA non-active site SET domain surface crucial for the interaction of MLL1 and the RbBP5-ASH2L heterodimer within MLL family core complexes.
Publication TypeJournal Article
Year of Publication2014
AuthorsShinsky SA, Hu M, Vought VE, Ng SB, Bamshad MJ, Shendure J, Cosgrove MS
JournalJ Mol Biol
Date Published2014 Mar 26
ISSN1089-8638
Abstract

The Mixed Lineage Leukemia-1 (MLL1) enzyme is a histone H3 lysine 4 (H3K4) monomethyltransferase and has served as a paradigm for understanding the mechanism of action of the human SET1 family of enzymes that include MLL1-4, and SET1d1a,b. Dimethylation of H3K4 requires a sub-complex including WDR5, RbBP5, Ash2L, and DPY-30 (WRAD), which binds to each SET1 family member forming a minimal core complex that is required for multiple lysine methylation. We recently demonstrated that WRAD is a novel histone methyltransferase that preferentially catalyzes H3K4 dimethylation in a manner that is dependent on an unknown non-active site surface from the MLL1 SET domain. Recent genome sequencing studies have identified a number of human disease-associated missense mutations that localize to the SET domains of several MLL family members. In this investigation, we mapped many of these mutations onto the three-dimensional structure of the SET domain and noticed that a subset of MLL2 (KMT2D, ALR, MLL4)-associated Kabuki syndrome (KS) missense mutations map to a common solvent-exposed surface that is not expected to alter enzymatic activity. We introduced these mutations into the MLL1 SET domain and observed that all are defective for H3K4 dimethylation by the MLL1 core complex, which is associated with a loss of the ability of MLL1 to interact with WRAD or with the RbBP5-Ash2L heterodimer. Our results suggest that amino acids from this surface, which we term the Kabuki interaction surface or (KIS), are required for formation of a second active site within SET1 family core complexes.

DOI10.1016/j.jmb.2014.03.011
Alternate JournalJ. Mol. Biol.
Citation Key1431
PubMed ID24680668