Spindlin-1 recognizes methylations of K20 and R23 of histone H4 tail.

Using methods combining cross-linking, pull-down assays, and stable isotope labeling by amino acids in cell culture with mass spectrometry, we identified that the Tudor domain-containing protein Spindlin-1 recognizes trimethylation of histone H4 lysine 20 (H4K20me3). The binding affinity of Spindlin-1 to H4K20me3 is weaker than that to H3K4me3, indicating H4K20me3 as a secondary substrate for Spindlin-1. Structural studies of Spindlin-1 in complex with the H4K20me3 peptide indicate that Spindlin-1 attains a distinct binding mode for H4K20me3 recognition. Further biochemical analysis identified that Spindlin-1 also binds methylated R23 of H4, providing new clues for the function of Spindlin-1.