Allosteric remodelling of the histone H3 binding pocket in the Pygo2 PHD finger triggered by its binding to the B9L/BCL9 co-factor.

ABSTRACT: The Zn-coordinated PHD fingers of Pygopus (Pygo) proteins are critical for beta-catenin-dependent transcriptional switches in normal and malignant tissues. They bind to methylated histone H3 tails, assisted by their BCL9 co-factors whose homology domain 1 (HD1) binds to the rear PHD surface. Although histone-binding residues are identical between the two human Pygo paralogs, we show here that Pygo2 complexes exhibit slightly higher binding affinities for methylated histone H3 tail peptides than Pygo1 complexes. We solved the crystal structure of the Pygo2 PHD-BCL9-2 HD1 complex, which revealed paralog-specific interactions in its PHD-HD1 interface that could contribute indirectly to its elevated affinity for the methylated histone H3 tail. Interestingly, using NMR spectroscopy, we discover

SUBMITTER: Miller TC 

PROVIDER: S-EPMC2927781 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature