Structural and histone binding studies of the chromo barrel domain of TIP60

TIP60 consists of an N-terminal chromo barrel domain (TIP60-CB) and a C-terminal acetyltransferase domain and acetylates histone and non-histone proteins within diverse cellular processes. Whereas the TIP60-CB is thought to recognize histone tails, molecular details of this interaction remain unclear. Here we attempted a quantitative analysis of the interaction between the TIP60-CB and histone peptides, but did not observe any binding through either fluorescence polarization or isothermal titration calorimetry. We solved a crystal structure of the TIP60-CB alone. Analysis of the crystal structure demonstrates a putative peptide binding site that may be occluded by the basic side chain of a residue in a unique β hairpin between the two N-terminal strands of the β barrel.