UNC1215S7088

UNC1215 binds L3MBTL3, competitively displacing mono- or dimethyllysine-containing peptides. This probe is greater than 50-fold selective versus other members of the human MBT family. UNC1215 has about a 75-fold selectivity for L3MBTL3 over L3MBTL1. UNC1215 shows no activity at concentrations up to 30 μM against the tandem Tudor domain of UHRF1, the chromodomain of CBX7 or the PHD domain of JARID1A. X-ray crystallography identifies a unique 2:2 polyvalent mode of interaction between UNC1215 and L3MBTL3. In cells, UNC1215 is nontoxic and directly binds L3MBTL3 via the Kme-binding pocket of the MBT domains. UNC1215 increases the cellular mobility of GFP-L3MBTL3 fusion proteins, and point mutants that disrupt the Kme-binding function of GFP-L3MBTL3 phenocopy the effects of UNC1215 on localization. UNC1215 is used to reveal a new Kme-dependent interaction of L3MBTL3 with BCLAF1, a protein implicated in DNA damage repair and apoptosis. ^[1]