Molecular insight into the PCNA-binding mode of FBH1.

F-box DNA helicase 1 (FBH1) is involved in the regulation of cell responses to replicative stress. FBH1 is recruited to stalled DNA replication fork by PCNA where it inhibits homologous recombination and catalyzes fork regression. Here, we report the structural basis for the molecular recognition of two distinctly different motifs of FBH1, FBH1 and FBH1, by PCNA. The crystal structure of PCNA in complex with FBH1 and analysis of NMR perturbations reveal overlapped FBH1 and FBH1 binding sites of PCNA and the dominant contribution of FBH1 in this interaction.