Mre11 ATLD17/18 mutation retains Tel1/ATM activity but blocks DNA double-strand break repair.
The Mre11 complex (Mre11-Rad50-Nbs1 or MRN) binds double-strand breaks where it interacts with CtIP/Ctp1/Sae2 and ATM/Tel1 to preserve genome stability through its functions in homology-directed repair, checkpoint signaling and telomere maintenance. Here, we combine biochemical, structural and in vivo functional studies to uncover key properties of Mre11-W243R, a mutation identified in two pediatric cancer patients with enhanced ataxia telangiectasia-like disorder. Purified human Mre11-W243R retains nuclease and DNA binding activities in vitro. X-ray crystallography of Pyrococcus furiosus Mre11 indicates that an analogous mutation leaves the overall Mre11 three-dimensional structure and nuclease sites intact but disorders surface loops expected to regulate DNA and Rad50 interactions. The equivalent W248R allele in fission yeast allows Mre11 to form an MRN complex that efficiently binds double-strand breaks, activates Tel1/ATM and maintains telomeres; yet, it causes hypersensitivity to ionizing radiation and collapsed replication forks, increased Rad52 foci, defective Chk1 signaling and meiotic failure. W248R differs from other ataxia telangiectasia-like disorder analog alleles by the reduced stability of its interaction with Rad50 in cell lysates. Collective results suggest a separation-of-function mutation that disturbs interactions amongst the MRN subunits and Ctp1 required for DNA end processing in vivo but maintains interactions sufficient for Tel1/ATM checkpoint and telomere maintenance functions.
Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037, USA.
Oliver
O
Limbo
Davide
D
Moiani
Aryandi
A
Kertokalio
Claire
C
Wyman
John A
JA
Tainer
Paul
P
Russell
D000595:Amino Acid Sequence; D034961:Antigens, Nuclear / Q000235:genetics; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics; D001260:Ataxia Telangiectasia / Q000235:genetics*; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000235:genetics; D005090:Exodeoxyribonucleases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D000072200:Ku Autoantigen; D000076228:MRE11 Homologue Protein; D008540:Meiosis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020027:Pyrococcus furiosus / Q000201:enzymology; D051721:Rad52 DNA Repair and Recombination Protein / Q000032:analysis; D012568:Schizosaccharomyces / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics* / Q000378:metabolism; D059505:Telomere Homeostasis; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D034961:Antigens, Nuclear; D019843:Archaeal Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; C480032:Rad50 protein, S pombe; D051721:Rad52 DNA Repair and Recombination Protein; D029702:Schizosaccharomyces pombe Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C513624:tel1 protein, S pombe; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D000076228:MRE11 Homologue Protein; C092453:Mre11 protein, S pombe; C415985:Mre11 protein, archaeal; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen