Rad50 Explained

DNA repair protein RAD50, also known as RAD50, is a protein that in humans is encoded by the RAD50 gene.^[1]

Function

The protein encoded by this gene is highly similar to Saccharomyces cerevisiae Rad50, a protein involved in DNA double-strand break repair. This protein forms a complex with MRE11 and NBS1 (also known as Xrs2 in yeast). This MRN complex (MRX complex in yeast) binds to broken DNA ends and displays numerous enzymatic activities that are required for double-strand break repair by nonhomologous end-joining or homologous recombination. Gene knockout studies of the mouse homolog of Rad50 suggest it is essential for cell growth and viability. Two alternatively spliced transcript variants of Rad50, which encode distinct proteins, have been reported.^[1]

Structure

Rad50 is a member of the structural maintenance of chromosomes (SMC) family of proteins.^[2] Like other SMC proteins, Rad50 contains a long internal coiled-coil domain that folds back on itself, bringing the N- and C-termini together to form a globular ABC ATPase head domain. Rad50 can dimerize both through its head domain and through a zinc-binding dimerization motif at the opposite end of the coiled-coil known as the “zinc-hook”.^[3] Results from atomic force microscopy suggest that in free Mre11-Rad50-Nbs1 complexes, the zinc-hooks of a single Rad50 dimer associate to form a closed loop, while the zinc-hooks snap apart upon binding DNA, adopting a conformation that is thought to enable zinc-hook-mediated tethering of broken DNA ends.^[4]

Interactions

Rad50 has been shown to interact with:

• BRCA1,^[5]
• MRE11A,^{[6] [7] [8] [9] [10]}
• NBN,^{[6] [9] [11] [12]}
• RINT1,^[13]
• TERF2IP,^[14] and
• TERF2.^{[14] [15]}

Evolutionary ancestry

Rad50 protein has been mainly studied in eukaryotes. However, recent work has shown that orthologs of the Rad50 protein are also conserved in extant prokaryotic archaea where they likely function in homologous recombinational repair.^[16] In the hyperthermophilic archeon Sulfolobus acidocaldarius, the Rad50 and Mre11 proteins interact and appear to have an active role in repair of DNA damages introduced by gamma radiation.^[17] These findings suggest that eukaryotic Rad50 may be descended from an ancestral archaeal Rad50 protein that served a role in homologous recombinational repair of DNA damage.

Diseases

Human RAD50 deficiency is an autosomal recessive syndrome that has been reported in patients with microcephaly and short stature. Their clinical phenotype resembled Nijmegen Breakage Syndrome. Cells from these patients showed increased radiosensitity with an impaired response to chromosome breaks. ^{[18] [19] [20]}

See also

• MRN complex
• Homologous recombination
• Nijmegen Breakage Syndrome

Further reading

• Stracker TH, Theunissen JW, Morales M, Petrini JH . The Mre11 complex and the metabolism of chromosome breaks: the importance of communicating and holding things together . DNA Repair (Amst.) . 3 . 8–9 . 845–54 . 2005 . 15279769 . 10.1016/j.dnarep.2004.03.014 .
• Dolganov GM . Human Rad50 is physically associated with human Mre11: identification of a conserved multiprotein complex implicated in recombinational DNA repair . Mol. Cell. Biol. . 16 . 9 . 4832–41 . 1996 . 8756642 . 231485 . 10.1128/MCB.16.9.4832. vanc. Maser RS . Novikov A . 3 . Tosto . L . Chong . S . Bressan . DA . Petrini . JH .
• Maser RS, Monsen KJ, Nelms BE, Petrini JH . hMre11 and hRad50 nuclear foci are induced during the normal cellular response to DNA double-strand breaks . Mol. Cell. Biol. . 17 . 10 . 6087–96 . 1997 . 9315668 . 232458 . 10.1128/MCB.17.10.6087.
• Carney JP . The hMre11/hRad50 protein complex and Nijmegen breakage syndrome: linkage of double-strand break repair to the cellular DNA damage response . Cell . 93 . 3 . 477–86 . 1998 . 9590181 . 10.1016/S0092-8674(00)81175-7 . vanc. Maser RS . Olivares H . 3 . Davis . Elizabeth M . Le Beau . Michelle . Yates . John R . Hays . Lara . Morgan . William F . Petrini . John H.J . 14548642 . free .
• Paull TT, Gellert M . The 3' to 5' exonuclease activity of Mre 11 facilitates repair of DNA double-strand breaks . Mol. Cell . 1 . 7 . 969–79 . 1998 . 9651580 . 10.1016/S1097-2765(00)80097-0 . free .
• Trujillo KM, Yuan SS, Lee EY, Sung P . Nuclease activities in a complex of human recombination and DNA repair factors Rad50, Mre11, and p95 . J. Biol. Chem. . 273 . 34 . 21447–50 . 1998 . 9705271 . 10.1074/jbc.273.34.21447 . free .
• Paull TT, Gellert M . Nbs1 potentiates ATP-driven DNA unwinding and endonuclease cleavage by the Mre11/Rad50 complex . Genes Dev. . 13 . 10 . 1276–88 . 1999 . 10346816 . 316715 . 10.1101/gad.13.10.1276 .
• Kim KK . Molecular cloning and characterization of splice variants of human RAD50 gene . Gene . 235 . 1–2 . 59–67 . 1999 . 10415333 . 10.1016/S0378-1119(99)00215-2 . vanc. Shin BA . Seo KH . 3 . Kim . P.N. . Koh . J.T. . Kim . J.H. . Park . B.R. .
• Zhong Q . Association of BRCA1 with the hRad50-hMre11-p95 complex and the DNA damage response . Science . 285 . 5428 . 747–50 . 1999 . 10426999 . 10.1126/science.285.5428.747 . vanc. Chen CF . Li S . 3 . Chen . Y . Wang . CC . Xiao . J . Chen . PL . Sharp . ZD . Lee . WH .
• Wang Y . BASC, a super complex of BRCA1-associated proteins involved in the recognition and repair of aberrant DNA structures . Genes Dev. . 14 . 8 . 927–39 . 2000 . 10783165 . 316544 . 10.1101/gad.14.8.927. vanc. Cortez D . Yazdi P . 3 . Neff . N . Elledge . SJ . Qin . J .
• Gatei M . ATM-dependent phosphorylation of nibrin in response to radiation exposure . Nat. Genet. . 25 . 1 . 115–9 . 2000 . 10802669 . 10.1038/75508 . vanc. Young D . Cerosaletti KM . 3 . Cerosaletti . Karen M. . Desai-Mehta . Ami . Spring . Kevin . Kozlov . Sergei . Lavin . Martin F. . Gatti . Richard A. . 23521589 .
• Zhao S . Functional link between ataxia-telangiectasia and Nijmegen breakage syndrome gene products . Nature . 405 . 6785 . 473–7 . 2000 . 10839544 . 10.1038/35013083 . vanc. Weng YC . Yuan SS . 3 . Yuan . Shyng-Shiou F. . Lin . Yi-Tzu . Hsu . Hao-Chi . Lin . Suh-Chin J. . Gerbino . Elvira . Song . Mei-hua . 2000Natur.405..473Z . 4428170 .
• Zhu XD . Cell-cycle-regulated association of RAD50/MRE11/NBS1 with TRF2 and human telomeres . Nat. Genet. . 25 . 3 . 347–52 . 2000 . 10888888 . 10.1038/77139 . vanc. Küster B . Mann M . 3 . Mann . Matthias . Petrini . John H.J. . 6689794 .
• Paull TT . A critical role for histone H2AX in recruitment of repair factors to nuclear foci after DNA damage . Curr. Biol. . 10 . 15 . 886–95 . 2001 . 10959836 . 10.1016/S0960-9822(00)00610-2 . vanc. Rogakou EP . Yamazaki V . 3 . Kirchgessner . Cordula U . Gellert . Martin . Bonner . William M . 16108315 . free.
• Xiao J, Liu CC, Chen PL, Lee WH . RINT-1, a novel Rad50-interacting protein, participates in radiation-induced G(2)/M checkpoint control . J. Biol. Chem. . 276 . 9 . 6105–11 . 2001 . 11096100 . 10.1074/jbc.M008893200 . free .
• Desai-Mehta A, Cerosaletti KM, Concannon P . Distinct functional domains of nibrin mediate Mre11 binding, focus formation, and nuclear localization . Mol. Cell. Biol. . 21 . 6 . 2184–91 . 2001 . 11238951 . 86852 . 10.1128/MCB.21.6.2184-2191.2001 .
• Buscemi G . Chk2 activation dependence on Nbs1 after DNA damage . Mol. Cell. Biol. . 21 . 15 . 5214–22 . 2001 . 11438675 . 87245 . 10.1128/MCB.21.15.5214-5222.2001 . vanc. Savio C . Zannini L . 3 . Micciche . F. . Masnada . D. . Nakanishi . M. . Tauchi . H. . Komatsu . K. . Mizutani . S. .
• Chiba N, Parvin JD . Redistribution of BRCA1 among four different protein complexes following replication blockage . J. Biol. Chem. . 276 . 42 . 38549–54 . 2001 . 11504724 . 10.1074/jbc.M105227200 . free .
• Grenon M, Gilbert C, Lowndes NF . Checkpoint activation in response to double-strand breaks requires the Mre11/Rad50/Xrs2 complex . Nat. Cell Biol. . 3 . 9 . 844–7 . 2001 . 11533665 . 10.1038/ncb0901-844 . 32286986 .
• de Jager M . Human Rad50/Mre11 is a flexible complex that can tether DNA ends . Mol. Cell . 8 . 5 . 1129–35 . 2002 . 11741547 . 10.1016/S1097-2765(01)00381-1 . vanc. van Noort J . van Gent DC . 3 . Dekker . Cees . Kanaar . Roland . Wyman . Claire . free .
• M. Beikzadeh, M.P. Latham. The dynamic nature of the Mre11-Rad50 DNA break repair complex . Progress in Biophysics and Molecular Biology . 2020 . 163 . 14–22 . 10.1016/j.pbiomolbio.2020.10.007 . 33121960. 8065065 . free .

Notes and References

1. Web site: Entrez Gene: RAD50 RAD50 homolog (S. cerevisiae).
2. Kinoshita E, van der Linden E, Sanchez H, Wyman C . RAD50, an SMC family member with multiple roles in DNA break repair: how does ATP affect function? . Chromosome Res. . 17 . 2 . 277–88 . 2009 . 19308707 . 4494100 . 10.1007/s10577-008-9018-6 .
3. Hopfner KP, Craig L, Moncalian G, Zinkel RA, Usui T, Owen BA, Karcher A, Henderson B, Bodmer JL, McMurray CT, Carney JP, Petrini JH, Tainer JA . The Rad50 zinc-hook is a structure joining Mre11 complexes in DNA recombination and repair . Nature . 418 . 6897 . 562–6 . August 2002 . 12152085 . 10.1038/nature00922 . 2002Natur.418..562H . 4414704 .
4. Moreno-Herrero F, de Jager M, Dekker NH, Kanaar R, Wyman C, Dekker C . Mesoscale conformational changes in the DNA-repair complex Rad50/Mre11/Nbs1 upon binding DNA . Nature . 437 . 7057 . 440–3 . September 2005 . 16163361 . 10.1038/nature03927 . 2005Natur.437..440M . 4357195 .
5. Zhong Q, Chen CF, Li S, Chen Y, Wang CC, Xiao J, Chen PL, Sharp ZD, Lee WH . Association of BRCA1 with the hRad50-hMre11-p95 complex and the DNA damage response . Science . 285 . 5428 . 747–50 . 1999 . 10426999 . 10.1126/science.285.5428.747.
6. Wang Y, Cortez D, Yazdi P, Neff N, Elledge SJ, Qin J . BASC, a super complex of BRCA1-associated proteins involved in the recognition and repair of aberrant DNA structures . Genes Dev. . 14 . 8 . 927–39 . 2000 . 10783165 . 316544 . 10.1101/gad.14.8.927.
7. Chiba N, Parvin JD . Redistribution of BRCA1 among four different protein complexes following replication blockage . J. Biol. Chem. . 276 . 42 . 38549–54 . 2001 . 11504724 . 10.1074/jbc.M105227200 . free .
8. Dolganov GM, Maser RS, Novikov A, Tosto L, Chong S, Bressan DA, Petrini JH . Human Rad50 is physically associated with human Mre11: identification of a conserved multiprotein complex implicated in recombinational DNA repair . Mol. Cell. Biol. . 16 . 9 . 4832–41 . 1996 . 8756642 . 231485 . 10.1128/MCB.16.9.4832.
9. Eva Y.-H. P. Lee . Trujillo KM, Yuan SS, Lee EY, Sung P . Nuclease activities in a complex of human recombination and DNA repair factors Rad50, Mre11, and p95 . J. Biol. Chem. . 273 . 34 . 21447–50 . 1998 . 9705271 . 10.1074/jbc.273.34.21447. free .
10. Goedecke W, Eijpe M, Offenberg HH, van Aalderen M, Heyting C . Mre11 and Ku70 interact in somatic cells, but are differentially expressed in early meiosis . Nat. Genet. . 23 . 2 . 194–8 . 1999 . 10508516 . 10.1038/13821 . 13443404 .
11. Cerosaletti KM, Concannon P . Nibrin forkhead-associated domain and breast cancer C-terminal domain are both required for nuclear focus formation and phosphorylation . J. Biol. Chem. . 278 . 24 . 21944–51 . 2003 . 12679336 . 10.1074/jbc.M211689200 . free .
12. Desai-Mehta A, Cerosaletti KM, Concannon P . Distinct functional domains of nibrin mediate Mre11 binding, focus formation, and nuclear localization . Mol. Cell. Biol. . 21 . 6 . 2184–91 . 2001 . 11238951 . 86852 . 10.1128/MCB.21.6.2184-2191.2001 .
13. Xiao J, Liu CC, Chen PL, Lee WH . RINT-1, a novel Rad50-interacting protein, participates in radiation-induced G(2)/M checkpoint control . J. Biol. Chem. . 276 . 9 . 6105–11 . 2001 . 11096100 . 10.1074/jbc.M008893200 . free .
14. O'Connor MS, Safari A, Liu D, Qin J, Songyang Z . The human Rap1 protein complex and modulation of telomere length . J. Biol. Chem. . 279 . 27 . 28585–91 . 2004 . 15100233 . 10.1074/jbc.M312913200 . free .
15. Zhu XD, Küster B, Mann M, Petrini JH, de Lange T . Cell-cycle-regulated association of RAD50/MRE11/NBS1 with TRF2 and human telomeres . Nat. Genet. . 25 . 3 . 347–52 . 2000 . 10888888 . 10.1038/77139 . 6689794 .
16. White MF . Homologous recombination in the archaea: the means justify the ends . Biochem. Soc. Trans. . 39 . 1 . 15–9 . January 2011 . 21265740 . 10.1042/BST0390015 . 239399 .
17. Quaiser A, Constantinesco F, White MF, Forterre P, Elie C . The Mre11 protein interacts with both Rad50 and the HerA bipolar helicase and is recruited to DNA following gamma irradiation in the archaeon Sulfolobus acidocaldarius . BMC Mol. Biol. . 9 . 25 . 2008 . 18294364 . 2288612 . 10.1186/1471-2199-9-25 . free .
18. Waltes R, Kalb R, Gatei M, Kijas AW, Stumm M, Sobeck A, Wieland B, Varon R, Lerenthal Y, Lavin MF, Schindler D, Dörk T . Human RAD50 deficiency in a Nijmegen Breakage Syndrome-like disorder . Am. J. Hum. Genet. . 84 . 5 . 605–16 . 2009 . 10.1016/j.ajhg.2009.04.010 . 19409520 . 2681000 .
19. Ragamin A, Yigit G, Bousset K, Beleggia F, Verheijen FW, de Wit MY, Strom TM, Dörk T, Wollnik B, Mancini GM . Human RAD50 deficiency: Confirmation of a distinctive phenotype . Am. J. Med. Genet. . 182 . 6 . 1378–86 . 2020 . 10.1002/ajmg.a.61570 . 32212377 . 7318339 .
20. Chansel-Da Cruz M, Hohl M, Ceppi I, Kermasson L, Maggiorella L, Modesti M, de Villartay J, Ileri T, Cejka P, Petrini J, Revy P . A Disease-Causing Single Amino Acid Deletion in the Coiled-Coil Domain of RAD50 Impairs MRE11 Complex Functions in Yeast and Humans . Cell Rep. . 33 . 13 . 108559 . 2020 . 10.1016/j.celrep.2020.108559 . 33378670 . 7788285 .