LAUSR

Abstract Histone acetylation is a key histone post‐translational modification that shapes chromatin structure, dynamics, and function. Bromodomain (BRD) proteins, the readers of acetyl‐lysines, are located in the center of the histone acetylation‐signaling network. How they regulate DNA repair and genome stability remains poorly understood. Here, a conserved function of the yeast Bromodomain Factor 1 (Bdf1) and its human counterpart TAF1 is reported in promoting DNA double‐stranded break repair by homologous recombination (HR). Depletion of either yeast BDF1 or human TAF1, or disruption of their BRDs impairs DNA end resection, Replication Protein A (RPA) and Rad51 loading, and HR repair, causing genome instability and hypersensitivity to DNA damage. Mechanistically, it is shown that Bdf1 preferentially binds the DNA damage‐induced histone H4 acetylation (H4Ac) via the BRD motifs, leading to its chromatin recruitment. Meanwhile, Bdf1 physically interacts with RPA, and this interaction facilitates RPA loading in the chromatin context and the subsequent HR repair. Similarly, TAF1 also interacts with H4Ac or RPA. Thus, Bdf1 and TAF1 appear to share a conserved mechanism in linking the HR repair to chromatin acetylation in preserving genome integrity.