A Method for Constructing Nucleosome Arrays with Spatially Defined Histone PTMs and DNA Damage.

DNA damage repair mechanisms, such as base excision repair (BER), safeguard cells against genotoxic agents that cause genetic instability and diseases, including cancer. In eukaryotic nuclei, DNA within nucleosome arrays is less accessible to repair factors than naked DNA owing to the structural constraints of chromatin. Histone acetylation is crucial for loosening the chromatin structure and facilitating access to damaged DNA, yet its effects-particularly in histone globular domains-on BER in nucleosome arrays remain unexplored. Herein, we employ an abiotic/enzymatic hybrid catalyst system (ABEHCS) and a plug-and-play strategy to regioselectively introduce histone acetylation and deoxycytidine-to-deoxyuridine DNA damage. This approach enables the construction of nucleosome arrays with diverse spatial configurations of histone acetylation and DNA lesions, similar to those found in living organisms. Our findings reveal that H3K56 acetylation in the histone globular domain enhances BER efficiency mediated by UDG and APE1 in nucleosome arrays, contingent upon the spatial relationship between H3K56Ac and the DNA damage site.