| Structural highlights
Function
[MDC1_HUMAN] Required for checkpoint mediated cell cycle arrest in response to DNA damage within both the S phase and G2/M phases of the cell cycle. May serve as a scaffold for the recruitment of DNA repair and signal transduction proteins to discrete foci of DNA damage marked by 'Ser-139' phosphorylation of histone H2AFX. Also required for downstream events subsequent to the recruitment of these proteins. These include phosphorylation and activation of the ATM, CHEK1 and CHEK2 kinases, and stabilization of TP53 and apoptosis. ATM and CHEK2 may also be activated independently by a parallel pathway mediated by TP53BP1.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
Publication Abstract from PubMed
MDC1 is a key mediator of the DNA-damage response in mammals with several phosphorylation-dependent protein interaction domains. The function of its N-terminal forkhead-associated (FHA) domain remains elusive. Here, we show with structural, biochemical and cellular data that the FHA domain mediates phosphorylation-dependent dimerization of MDC1 in response to DNA damage. Crystal structures of the FHA domain reveal a face-to-face dimer with pseudo-dyad symmetry. We found that the FHA domain recognizes phosphothreonine 4 (pT4) at the N-terminus of MDC1 and determined its crystal structure in complex with a pT4 peptide. Biochemical analysis further revealed that in the dimer, the FHA domain binds in trans to pT4 from the other subunit, which greatly stabilizes the otherwise unstable dimer. We show that T4 is phosphorylated primarily by ATM upon DNA damage. MDC1 mutants with the FHA domain deleted or impaired in its ability to dimerize formed fewer foci at DNA-damage sites, but the localization defect was largely rescued by an artificial dimerization module, suggesting that dimerization is the primary function of the MDC1 FHA domain. Our results suggest a novel mechanism for the regulation of MDC1 function through T4 phosphorylation and FHA-mediated dimerization.
Structural mechanism of the phosphorylation-dependent dimerization of the MDC1 forkhead-associated domain.,Liu J, Luo S, Zhao H, Liao J, Li J, Yang C, Xu B, Stern DF, Xu X, Ye K Nucleic Acids Res. 2012 Jan 10. PMID:22234877[11]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Mochan TA, Venere M, DiTullio RA Jr, Halazonetis TD. 53BP1 and NFBD1/MDC1-Nbs1 function in parallel interacting pathways activating ataxia-telangiectasia mutated (ATM) in response to DNA damage. Cancer Res. 2003 Dec 15;63(24):8586-91. PMID:14695167
- ↑ Shang YL, Bodero AJ, Chen PL. NFBD1, a novel nuclear protein with signature motifs of FHA and BRCT, and an internal 41-amino acid repeat sequence, is an early participant in DNA damage response. J Biol Chem. 2003 Feb 21;278(8):6323-9. Epub 2002 Dec 9. PMID:12475977 doi:10.1074/jbc.M210749200
- ↑ Xu X, Stern DF. NFBD1/KIAA0170 is a chromatin-associated protein involved in DNA damage signaling pathways. J Biol Chem. 2003 Mar 7;278(10):8795-803. Epub 2002 Dec 23. PMID:12499369 doi:10.1074/jbc.M211392200
- ↑ Peng A, Chen PL. NFBD1, like 53BP1, is an early and redundant transducer mediating Chk2 phosphorylation in response to DNA damage. J Biol Chem. 2003 Mar 14;278(11):8873-6. Epub 2003 Jan 24. PMID:12551934 doi:10.1074/jbc.C300001200
- ↑ Lou Z, Chini CC, Minter-Dykhouse K, Chen J. Mediator of DNA damage checkpoint protein 1 regulates BRCA1 localization and phosphorylation in DNA damage checkpoint control. J Biol Chem. 2003 Apr 18;278(16):13599-602. Epub 2003 Feb 27. PMID:12611903 doi:10.1074/jbc.C300060200
- ↑ Goldberg M, Stucki M, Falck J, D'Amours D, Rahman D, Pappin D, Bartek J, Jackson SP. MDC1 is required for the intra-S-phase DNA damage checkpoint. Nature. 2003 Feb 27;421(6926):952-6. PMID:12607003 doi:10.1038/nature01445
- ↑ Lou Z, Minter-Dykhouse K, Wu X, Chen J. MDC1 is coupled to activated CHK2 in mammalian DNA damage response pathways. Nature. 2003 Feb 27;421(6926):957-61. PMID:12607004 doi:10.1038/nature01447
- ↑ Stewart GS, Wang B, Bignell CR, Taylor AM, Elledge SJ. MDC1 is a mediator of the mammalian DNA damage checkpoint. Nature. 2003 Feb 27;421(6926):961-6. PMID:12607005 doi:10.1038/nature01446
- ↑ Lukas C, Melander F, Stucki M, Falck J, Bekker-Jensen S, Goldberg M, Lerenthal Y, Jackson SP, Bartek J, Lukas J. Mdc1 couples DNA double-strand break recognition by Nbs1 with its H2AX-dependent chromatin retention. EMBO J. 2004 Jul 7;23(13):2674-83. Epub 2004 Jun 17. PMID:15201865 doi:10.1038/sj.emboj.7600269
- ↑ Lou Z, Chen BP, Asaithamby A, Minter-Dykhouse K, Chen DJ, Chen J. MDC1 regulates DNA-PK autophosphorylation in response to DNA damage. J Biol Chem. 2004 Nov 5;279(45):46359-62. Epub 2004 Sep 17. PMID:15377652 doi:10.1074/jbc.C400375200
- ↑ Liu J, Luo S, Zhao H, Liao J, Li J, Yang C, Xu B, Stern DF, Xu X, Ye K. Structural mechanism of the phosphorylation-dependent dimerization of the MDC1 forkhead-associated domain. Nucleic Acids Res. 2012 Jan 10. PMID:22234877 doi:10.1093/nar/gkr1296
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