Mre11 assembles linear DNA fragments into DNA damage signaling complexes.
Mre11/Rad50/Nbs1 complex (MRN) is essential to suppress the generation of double-strand breaks (DSBs) during DNA replication. MRN also plays a role in the response to DSBs created by DNA damage. Hypomorphic mutations in Mre11 (which causes an ataxia-telangiectasia-like disease [ATLD]) and mutations in the ataxia-telangiectasia-mutated (ATM) gene lead to defects in handling damaged DNA and to similar clinical and cellular phenotypes. Using Xenopus egg extracts, we have designed a simple assay to define the biochemistry of Mre11. MRN is required for efficient activation of the DNA damage response induced by DSBs. We isolated a high molecular weight DNA damage signaling complex that includes MRN, damaged DNA molecules, and activated ATM. Complex formation is partially dependent upon Zn(2+) and requires an intact Mre11 C-terminal domain that is deleted in some ATLD patients. The ATLD truncation can still perform the role of Mre11 during replication. Our work demonstrates the role of Mre11 in assembling DNA damage signaling centers that are reminiscent of irradiation-induced foci. It also provides a molecular explanation for the similarities between ataxia-telangiectasia (A-T) and ATLD.
Costanzo
Vincenzo
V
Department of Genetics and Development, Columbia University, New York, New York, USA.
Paull
Tanya
T
Gottesman
Max
M
Gautier
Jean
J
D020816:Amino Acid Motifs; D000818:Animals; D034961:Antigens, Nuclear / Q000737:chemistry; D019921:Biotinylation; D015153:Blotting, Western; D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D019281:Dimerization; D017353:Gene Deletion; D006801:Humans; D020287:In Situ Nick-End Labeling; D000072200:Ku Autoantigen; D000076228:MRE11 Homologue Protein; D018625:Microscopy, Atomic Force; D008970:Molecular Weight; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D051716:Replication Protein A / Q000378:metabolism; D015398:Signal Transduction; D014981:Xenopus; D015032:Zinc / Q000737:chemistry
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; D010455:Peptides; D011994:Recombinant Proteins; D051716:Replication Protein A; D004247:DNA; D000076228:MRE11 Homologue Protein; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D015032:Zinc