The "readers" of unacetylated p53 represent a new class of acidic domain proteins.

Acetylation of non-histone proteins plays important roles in regulating protein functions but the mechanisms of action are poorly understood. Our recent study uncovered a previously unknown mechanism by which C-terminal domain (CTD) acetylation of p53 serves as a "switch" to determine the interaction between a unique group of acidic domain-containing proteins and p53, as well as revealed that acidic domains may act as a novel class of "readers" for unacetylated p53. However, the properties of acidic domain "readers" are not well elucidated yet. Here, we identified that the charge effect between acidic domain "readers" and the p53 CTD is necessary for their interaction. Both the length and the amino acid composition of a given acidic domain contributed to its ability to recognize the p53 CTD. Finally, we summarized the characteristic features of our identified acidic domains, which would distinguish this kind of "readers" from other types of acidic amino acid-containing domains.