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Structural highlights

Function

RAG1_MOUSE Catalytic component of the RAG complex, a multiprotein complex that mediates the DNA cleavage phase during V(D)J recombination. V(D)J recombination assembles a diverse repertoire of immunoglobulin and T-cell receptor genes in developing B and T-lymphocytes through rearrangement of different V (variable), in some cases D (diversity), and J (joining) gene segments. In the RAG complex, RAG1 mediates the DNA-binding to the conserved recombination signal sequences (RSS) and catalyzes the DNA cleavage activities by introducing a double-strand break between the RSS and the adjacent coding segment. RAG2 is not a catalytic component but is required for all known catalytic activities. DNA cleavage occurs in 2 steps: a first nick is introduced in the top strand immediately upstream of the heptamer, generating a 3'-hydroxyl group that can attack the phosphodiester bond on the opposite strand in a direct transesterification reaction, thereby creating 4 DNA ends: 2 hairpin coding ends and 2 blunt, 5'-phosphorylated ends. The chromatin structure plays an essential role in the V(D)J recombination reactions and the presence of histone H3 trimethylated at 'Lys-4' (H3K4me3) stimulates both the nicking and haipinning steps. The RAG complex also plays a role in pre-B cell allelic exclusion, a process leading to expression of a single immunoglobulin heavy chain allele to enforce clonality and monospecific recognition by the B-cell antigen receptor (BCR) expressed on individual B-lymphocytes. The introduction of DNA breaks by the RAG complex on one immunoglobulin allele induces ATM-dependent repositioning of the other allele to pericentromeric heterochromatin, preventing accessibility to the RAG complex and recombination of the second allele. In addition to its endonuclease activity, RAG1 also acts as a E3 ubiquitin-protein ligase that mediates monoubiquitination of histone H3. Histone H3 monoubiquitination is required for the joining step of V(D)J recombination. Mediates polyubiquitination of KPNA1.^{[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]}

References

1. ↑ Schatz DG, Oettinger MA, Baltimore D. The V(D)J recombination activating gene, RAG-1. Cell. 1989 Dec 22;59(6):1035-48. PMID:2598259
2. ↑ McBlane JF, van Gent DC, Ramsden DA, Romeo C, Cuomo CA, Gellert M, Oettinger MA. Cleavage at a V(D)J recombination signal requires only RAG1 and RAG2 proteins and occurs in two steps. Cell. 1995 Nov 3;83(3):387-95. PMID:8521468
3. ↑ Agrawal A, Schatz DG. RAG1 and RAG2 form a stable postcleavage synaptic complex with DNA containing signal ends in V(D)J recombination. Cell. 1997 Apr 4;89(1):43-53. PMID:9094713
4. ↑ Landree MA, Wibbenmeyer JA, Roth DB. Mutational analysis of RAG1 and RAG2 identifies three catalytic amino acids in RAG1 critical for both cleavage steps of V(D)J recombination. Genes Dev. 1999 Dec 1;13(23):3059-69. PMID:10601032
5. ↑ Fugmann SD, Villey IJ, Ptaszek LM, Schatz DG. Identification of two catalytic residues in RAG1 that define a single active site within the RAG1/RAG2 protein complex. Mol Cell. 2000 Jan;5(1):97-107. PMID:10678172
6. ↑ Yurchenko V, Xue Z, Sadofsky M. The RAG1 N-terminal domain is an E3 ubiquitin ligase. Genes Dev. 2003 Mar 1;17(5):581-5. PMID:12629039 doi:http://dx.doi.org/10.1101/gad.1058103
7. ↑ Jones JM, Gellert M. Autoubiquitylation of the V(D)J recombinase protein RAG1. Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15446-51. Epub 2003 Dec 11. PMID:14671314 doi:http://dx.doi.org/10.1073/pnas.2637012100
8. ↑ Lu CP, Sandoval H, Brandt VL, Rice PA, Roth DB. Amino acid residues in Rag1 crucial for DNA hairpin formation. Nat Struct Mol Biol. 2006 Nov;13(11):1010-5. Epub 2006 Oct 8. PMID:17028591 doi:http://dx.doi.org/10.1038/nsmb1154
9. ↑ Shimazaki N, Tsai AG, Lieber MR. H3K4me3 stimulates the V(D)J RAG complex for both nicking and hairpinning in trans in addition to tethering in cis: implications for translocations. Mol Cell. 2009 Jun 12;34(5):535-44. doi: 10.1016/j.molcel.2009.05.011. PMID:19524534 doi:http://dx.doi.org/10.1016/j.molcel.2009.05.011
10. ↑ Simkus C, Makiya M, Jones JM. Karyopherin alpha 1 is a putative substrate of the RAG1 ubiquitin ligase. Mol Immunol. 2009 Apr;46(7):1319-25. doi: 10.1016/j.molimm.2008.11.009. Epub 2008, Dec 31. PMID:19118899 doi:http://dx.doi.org/10.1016/j.molimm.2008.11.009
11. ↑ Hewitt SL, Yin B, Ji Y, Chaumeil J, Marszalek K, Tenthorey J, Salvagiotto G, Steinel N, Ramsey LB, Ghysdael J, Farrar MA, Sleckman BP, Schatz DG, Busslinger M, Bassing CH, Skok JA. RAG-1 and ATM coordinate monoallelic recombination and nuclear positioning of immunoglobulin loci. Nat Immunol. 2009 Jun;10(6):655-64. doi: 10.1038/ni.1735. PMID:19448632 doi:http://dx.doi.org/10.1038/ni.1735
12. ↑ Grazini U, Zanardi F, Citterio E, Casola S, Goding CR, McBlane F. The RING domain of RAG1 ubiquitylates histone H3: a novel activity in chromatin-mediated regulation of V(D)J joining. Mol Cell. 2010 Jan 29;37(2):282-93. doi: 10.1016/j.molcel.2009.12.035. PMID:20122409 doi:http://dx.doi.org/10.1016/j.molcel.2009.12.035
13. ↑ Yin FF, Bailey S, Innis CA, Ciubotaru M, Kamtekar S, Steitz TA, Schatz DG. Structure of the RAG1 nonamer binding domain with DNA reveals a dimer that mediates DNA synapsis. Nat Struct Mol Biol. 2009 May;16(5):499-508. Epub 2009 Apr 26. PMID:19396172 doi:http://dx.doi.org/10.1038/nsmb.1593