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Structural highlights

Disease

[RN168_HUMAN] Defects in RNF168 are the cause of Riddle syndrome (RIDDLES) [MIM:611943]. Riddle syndrome is characterized by increased radiosensitivity, immunodeficiency, mild motor control and learning difficulties, facial dysmorphism, and short stature. Defects are probably due to impaired localization of TP53BP1 and BRCA1 at DNA lesions.^[1]

Function

[RS27A_MOUSE] Ubiquitin: Exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, DNA-damage responses as well as in signaling processes leading to activation of the transcription factor NF-kappa-B. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling.^[2] 40S Ribosomal protein S27a: Component of the 40S subunit of the ribosome.^[3] [RN168_HUMAN] E3 ubiquitin-protein ligase required for accumulation of repair proteins to sites of DNA damage. Acts with UBE2N/UBC13 to amplify the RNF8-dependent histone ubiquitination. Recruited to sites of DNA damage at double-strand breaks (DSBs) by binding to ubiquitinated histone H2A and H2AX and amplifies the RNF8-dependent H2A ubiquitination, promoting the formation of 'Lys-63'-linked ubiquitin conjugates. This leads to concentrate ubiquitinated histones H2A and H2AX at DNA lesions to the threshold required for recruitment of TP53BP1 and BRCA1. Also recruited at DNA interstrand cross-links (ICLs) sites and promotes accumulation of 'Lys-63'-linked ubiquitination of histones H2A and H2AX, leading to recruitment of FAAP20/C1orf86 and Fanconi anemia (FA) complex, followed by interstrand cross-link repair. H2A ubiquitination also mediates the ATM-dependent transcriptional silencing at regions flanking DSBs in cis, a mechanism to avoid collision between transcription and repair intermediates. Also involved in class switch recombination in immune system, via its role in regulation of DSBs repair. Following DNA damage, promotes the ubiquitination and degradation of JMJD2A/KDM4A in collaboration with RNF8, leading to unmask H4K20me2 mark and promote the recruitment of TP53BP1 at DNA damage sites. Not able to initiate 'Lys-63'-linked ubiquitination in vitro; possibly due to partial occlusion of the UBE2N/UBC13-binding region. Catalyzes monoubiquitination of 'Lys-13' and 'Lys-15' of nucleosomal histone H2A (H2AK13Ub and H2AK15Ub, respectively).^{[4] [5] [6] [7] [8] [9] [10] [11]}

References

1. ↑ Stewart GS, Panier S, Townsend K, Al-Hakim AK, Kolas NK, Miller ES, Nakada S, Ylanko J, Olivarius S, Mendez M, Oldreive C, Wildenhain J, Tagliaferro A, Pelletier L, Taubenheim N, Durandy A, Byrd PJ, Stankovic T, Taylor AM, Durocher D. The RIDDLE syndrome protein mediates a ubiquitin-dependent signaling cascade at sites of DNA damage. Cell. 2009 Feb 6;136(3):420-34. doi: 10.1016/j.cell.2008.12.042. PMID:19203578 doi:10.1016/j.cell.2008.12.042
2. ↑ Komander D. The emerging complexity of protein ubiquitination. Biochem Soc Trans. 2009 Oct;37(Pt 5):937-53. doi: 10.1042/BST0370937. PMID:19754430 doi:10.1042/BST0370937
3. ↑ Komander D. The emerging complexity of protein ubiquitination. Biochem Soc Trans. 2009 Oct;37(Pt 5):937-53. doi: 10.1042/BST0370937. PMID:19754430 doi:10.1042/BST0370937
4. ↑ Stewart GS, Panier S, Townsend K, Al-Hakim AK, Kolas NK, Miller ES, Nakada S, Ylanko J, Olivarius S, Mendez M, Oldreive C, Wildenhain J, Tagliaferro A, Pelletier L, Taubenheim N, Durandy A, Byrd PJ, Stankovic T, Taylor AM, Durocher D. The RIDDLE syndrome protein mediates a ubiquitin-dependent signaling cascade at sites of DNA damage. Cell. 2009 Feb 6;136(3):420-34. doi: 10.1016/j.cell.2008.12.042. PMID:19203578 doi:10.1016/j.cell.2008.12.042
5. ↑ Doil C, Mailand N, Bekker-Jensen S, Menard P, Larsen DH, Pepperkok R, Ellenberg J, Panier S, Durocher D, Bartek J, Lukas J, Lukas C. RNF168 binds and amplifies ubiquitin conjugates on damaged chromosomes to allow accumulation of repair proteins. Cell. 2009 Feb 6;136(3):435-46. doi: 10.1016/j.cell.2008.12.041. PMID:19203579 doi:10.1016/j.cell.2008.12.041
6. ↑ Shanbhag NM, Rafalska-Metcalf IU, Balane-Bolivar C, Janicki SM, Greenberg RA. ATM-dependent chromatin changes silence transcription in cis to DNA double-strand breaks. Cell. 2010 Jun 11;141(6):970-81. doi: 10.1016/j.cell.2010.04.038. PMID:20550933 doi:10.1016/j.cell.2010.04.038
7. ↑ Gatti M, Pinato S, Maspero E, Soffientini P, Polo S, Penengo L. A novel ubiquitin mark at the N-terminal tail of histone H2As targeted by RNF168 ubiquitin ligase. Cell Cycle. 2012 Jul 1;11(13):2538-44. doi: 10.4161/cc.20919. Epub 2012 Jul 1. PMID:22713238 doi:10.4161/cc.20919
8. ↑ Mallette FA, Mattiroli F, Cui G, Young LC, Hendzel MJ, Mer G, Sixma TK, Richard S. RNF8- and RNF168-dependent degradation of KDM4A/JMJD2A triggers 53BP1 recruitment to DNA damage sites. EMBO J. 2012 Feb 28;31(8):1865-78. doi: 10.1038/emboj.2012.47. PMID:22373579 doi:10.1038/emboj.2012.47
9. ↑ Yan Z, Guo R, Paramasivam M, Shen W, Ling C, Fox D 3rd, Wang Y, Oostra AB, Kuehl J, Lee DY, Takata M, Hoatlin ME, Schindler D, Joenje H, de Winter JP, Li L, Seidman MM, Wang W. A ubiquitin-binding protein, FAAP20, links RNF8-mediated ubiquitination to the Fanconi anemia DNA repair network. Mol Cell. 2012 Jul 13;47(1):61-75. doi: 10.1016/j.molcel.2012.05.026. Epub 2012, Jun 14. PMID:22705371 doi:10.1016/j.molcel.2012.05.026
10. ↑ Panier S, Ichijima Y, Fradet-Turcotte A, Leung CC, Kaustov L, Arrowsmith CH, Durocher D. Tandem protein interaction modules organize the ubiquitin-dependent response to DNA double-strand breaks. Mol Cell. 2012 Aug 10;47(3):383-95. doi: 10.1016/j.molcel.2012.05.045. Epub 2012 , Jun 27. PMID:22742833 doi:10.1016/j.molcel.2012.05.045
11. ↑ Mattiroli F, Vissers JH, van Dijk WJ, Ikpa P, Citterio E, Vermeulen W, Marteijn JA, Sixma TK. RNF168 Ubiquitinates K13-15 on H2A/H2AX to Drive DNA Damage Signaling. Cell. 2012 Sep 14;150(6):1182-95. doi: 10.1016/j.cell.2012.08.005. PMID:22980979 doi:10.1016/j.cell.2012.08.005
12. ↑ Takahashi TS, Hirade Y, Toma A, Sato Y, Yamagata A, Goto-Ito S, Tomita A, Nakada S, Fukai S. Structural insights into two distinct binding modules for Lys63-linked polyubiquitin chains in RNF168. Nat Commun. 2018 Jan 12;9(1):170. doi: 10.1038/s41467-017-02345-y. PMID:29330428 doi:http://dx.doi.org/10.1038/s41467-017-02345-y