The Mre11 complex mediates the S-phase checkpoint through an interaction with replication protein A.
The Mre11/Rad50/Nbs1 complex (MRN) plays an essential role in the S-phase checkpoint. Cells derived from patients with Nijmegen breakage syndrome and ataxia telangiectasia-like disorder undergo radioresistant DNA synthesis (RDS), failing to suppress DNA replication in response to ionizing radiation (IR). How MRN affects DNA replication to control the S-phase checkpoint, however, remains unclear. We demonstrate that MRN directly interacts with replication protein A (RPA) in unperturbed cells and that the interaction is regulated by cyclin-dependent kinases. We also show that this interaction is needed for MRN to correctly localize to replication centers. Abolishing the interaction of Mre11 with RPA leads to pronounced RDS without affecting phosphorylation of Nbs1 or SMC1 following IR. Moreover, MRN is recruited to sites at or adjacent to replication origins by RPA and acts there to inhibit new origin firing upon IR. These studies suggest a direct role of MRN at origin-proximal sites to control DNA replication initiation in response to DNA damage, thereby providing an important mechanism underlying the intra-S-phase checkpoint in mammalian cells.
Olson
Erin
E
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
Nievera
Christian J
CJ
Liu
Enbo
E
Lee
Alan Yueh-Luen
AY
Chen
Longchuan
L
Wu
Xiaohua
X
D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018816:Genes, cdc; D006801:Humans; D000076228:MRE11 Homologue Protein; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D051716:Replication Protein A / Q000378:metabolism*; D016196:S Phase / Q000502:physiology*; D016415:Sequence Alignment
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; D046912:Multiprotein Complexes; C112156:NBN protein, human; D009687:Nuclear Proteins; D051716:Replication Protein A; D018844:Cyclin-Dependent Kinases; D000076228:MRE11 Homologue Protein