Zou, LeeLiu, DouElledge, Stephen J.2019-10-122003Zou, L., D. Liu, and S. J. Elledge. 2003. “Replication Protein A-Mediated Recruitment and Activation of Rad17 Complexes.” Proceedings of the National Academy of Sciences100 (24): 13827–32. doi:10.1073/pnas.2336100100.0027-84240744-28311091-6490http://nrs.harvard.edu/urn-3:HUL.InstRepos:41542627The human Rad17-Rfc2-5 and Rad9-Rad1-Hus1 complexes play crucial roles in the activation of the ATR-mediated DNA damage and DNA replication stress response pathways. In response to DNA damage, Rad9 is recruited to chromatin in a Rad17-dependent manner in human cells. However, the DNA structures recognized by the Rad17-Rfc2-5 complex during the damage response have not been defined. Here, we show that replication protein A (RPA) stimulates the binding of the Rad17-Rfc2-5 complex to single-stranded DNA (ssDNA), primed ssDNA, and a gapped DNA structure. Furthermore, RPA facilitates the recruitment of the Rad9-Rad1-Hus1 complex by the Rad17-Rfc2-5 complex to primed and gapped DNA structures in vitro. These findings suggest that RPA-coated ssDNA is an important part of the structures recognized by the Rad17-Rfc2-5 complex. Unlike replication factor C (RFC), which uses the 3' primer/template junction to recruit proliferating cell nuclear antigen (PCNA), the Rad17-Rfc2-5 complex can use both the 5' and the 3' primer/template junctions to recruit the Rad9-Rad1-Hus1 complex, and it shows a preference for gapped DNA structures. These results explain how the Rad17-Rfc2-5 complex senses DNA damage and DNA replication stress to initiate checkpoint signaling.en-USJournal Article2019-10-1210.1073/pnas.2336100100