Fig. 5

R1627W mutation impairs EP300 HAT activity by disrupting substrate-binding capacity. A Lower level of TP53 acetylation are found in cells expressing EP300-R1627W than those expressing EP300-wt. TP53 was first immunoprecipitated, and then TP53 acetylation was assessed using pan-lysine acetylation antibody. B R1627 positions in close to, but not direct contact with, the HAT catalytic core of EP300. A long loop (blue), together with its hydrogen-bonding interaction (red sticks) and hydrophobic interaction (pink sticks) amino acids, forms the catalytic core that embraces the substrate (yellow sphere). C, D Protein surface views of EP300-wt (left) and EP300-R1627W (right) catalytic core, which were analyzed and rendered using Pymol software. The side chain of T1357, E1505, D1625 and D1627 (blue) form a negative potential of a pocket for polypeptide substrate binding. R1627/W1627 is intimate facing this pocket. Side chain resulted from R > W substitution could greatly disrupt the electrostatic property of the pocket