A trick of the tail: how electrostatics helps a DNA repair enzyme to localize on nucleosomes

Electrostatic interactions are key to the recognition processes of proteins and DNA and have been previously documented for the action of repair enzymes. Uracil-DNA glycosylase (UDG) is the first in a sequence of enzymes that act in the base-excision repair process (BER) and whose task is the extraction of uracil bases from nuclear DNA. The question of how the molecule targets uracil bases in chromatin, in particular in the condensed protein-DNA complexes of nucleosomes, has only recently become a subject of detailed studies. Here we show that the presence of an arginine anchor motif on the N-terminal tail of UDG can favor its localization on nucleosomes by binding to their acidic patches on their top and bottom surfaces via electrostatic interactions. We argue that this mechanism can play a key role in the detection of uracil defects in nucleosomal DNA.