|  |   Structural highlights   Disease [MLL1_HUMAN] Defects in MLL are the cause of Wiedemann-Steiner syndrome (WDSTS) [MIM:605130]. A syndrome characterized by hairy elbows (hypertrichosis cubiti), intellectual disability, a distinctive facial appearance, and short stature. Facial characteristics include long eyelashes, thick or arched eyebrows with a lateral flare, and downslanting and vertically narrow palpebral fissures.[1] [2]   Note=Chromosomal aberrations involving MLL are a cause of acute leukemias. Translocation t(1;11)(q21;q23) with MLLT11/AF1Q; translocation t(3;11)(p21;q23) with NCKIPSD/AF3p21; translocation t(3,11)(q25,q23) with GMPS; translocation t(4;11)(q21;q23) with AFF1/MLLT2/AF4; insertion ins(5;11)(q31;q13q23) with AFF4/AF5Q31; translocation t(5;11)(q12;q23) with AF5-alpha/CENPK; translocation t(6;11)(q27;q23) with MLLT4/AF6; translocation t(9;11)(p22;q23) with MLLT3/AF9; translocation t(10;11)(p11.2;q23) with ABI1; translocation t(10;11)(p12;q23) with MLLT10/AF10; t(11;15)(q23;q14) with CASC5 and ZFYVE19; translocation t(11;17)(q23;q21) with MLLT6/AF17; translocation t(11;19)(q23;p13.3) with ELL; translocation t(11;19)(q23;p13.3) with MLLT1/ENL; translocation t(11;19)(q23;p23) with GAS7; translocation t(X;11)(q13;q23) with FOXO4/AFX1. Translocation t(3;11)(q28;q23) with LPP. Translocation t(10;11)(q22;q23) with TET1. Translocation t(9;11)(q34;q23) with DAB2IP. Translocation t(4;11)(p12;q23) with FRYL. Fusion proteins MLL-MLLT1, MLL-MLLT3 and MLL-ELL interact with PPP1R15A and, on the contrary to unfused MLL, inhibit PPP1R15A-induced apoptosis.[3]   Note=A chromosomal aberration involving MLL may be a cause of chronic neutrophilic leukemia. Translocation t(4;11)(q21;q23) with SEPT11.[4]  
   Function [WDR5_HUMAN] Contributes to histone modification. May position the N-terminus of histone H3 for efficient trimethylation at 'Lys-4'. As part of the MLL1/MLL complex it is involved in methylation and dimethylation at 'Lys-4' of histone H3. H3 'Lys-4' methylation represents a specific tag for epigenetic transcriptional activation. As part of the NSL complex it may be involved in acetylation of nucleosomal histone H4 on several lysine residues. May regulate osteoblasts differentiation.[5] [6] [7] [8] [9]  [MLL1_HUMAN] Histone methyltransferase that plays an essential role in early development and hematopoiesis. Catalytic subunit of the MLL1/MLL complex, a multiprotein complex that mediates both methylation of 'Lys-4' of histone H3 (H3K4me) complex and acetylation of 'Lys-16' of histone H4 (H4K16ac). In the MLL1/MLL complex, it specifically mediates H3K4me, a specific tag for epigenetic transcriptional activation. Has weak methyltransferase activity by itself, and requires other component of the MLL1/MLL complex to obtain full methyltransferase activity. Has no activity toward histone H3 phosphorylated on 'Thr-3', less activity toward H3 dimethylated on 'Arg-8' or 'Lys-9', while it has higher activity toward H3 acetylated on 'Lys-9'. Required for transcriptional activation of HOXA9. Promotes PPP1R15A-induced apoptosis.[10] [11] [12] [13]  [RBBP5_HUMAN] In embryonic stem (ES) cells, plays a crucial role in the differentiation potential, particularly along the neural lineage, regulating gene induction and H3 'Lys-4' methylation at key developmental loci, including that mediated by retinoic acid (By similarity). As part of the MLL1/MLL complex, involved in mono-, di- and trimethylation at 'Lys-4' of histone H3. Histone H3 'Lys-4' methylation represents a specific tag for epigenetic transcriptional activation.[14]  
 
  Publication Abstract from PubMed Histone H3 Lys-4 methylation is predominantly catalyzed by a family of methyltransferases whose enzymatic activity depends on their interaction with a three-subunit complex composed of WDR5, RbBP5, and Ash2L. Here, we report that a segment of 50 residues of RbBP5 bridges the Ash2L C-terminal domain to WDR5. The crystal structure of WDR5 in ternary complex with RbBP5 and MLL1 reveals that both proteins binds peptide-binding clefts located on opposite sides of WDR5's beta-propeller domain. RbBP5 engages in several hydrogen bonds and van der Waals contacts within a V-shaped cleft formed by the junction of two blades on WDR5. Mutational analyses of both the WDR5 V-shaped cleft and RbBP5 residues reveal that the interactions between RbBP5 and WDR5 are important for the stimulation of MLL1 methyltransferase activity. Overall, this study provides the structural basis underlying the formation of the WDR5-RbBP5 subcomplex and further highlight the crucial role of WDR5 in scaffolding the MLL1 core complex.
 Structural and biochemical insights into MLL1 core complex assembly.,Avdic V, Zhang P, Lanouette S, Groulx A, Tremblay V, Brunzelle J, Couture JF Structure. 2011 Jan 12;19(1):101-8. PMID:21220120[15]
 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
  See Also  References ↑ Adler HT, Chinery R, Wu DY, Kussick SJ, Payne JM, Fornace AJ Jr, Tkachuk DC. Leukemic HRX fusion proteins inhibit GADD34-induced apoptosis and associate with  the GADD34 and hSNF5/INI1 proteins. Mol Cell Biol. 1999 Oct;19(10):7050-60. PMID:10490642 ↑ Jones WD, Dafou D, McEntagart M, Woollard WJ, Elmslie FV, Holder-Espinasse M, Irving M, Saggar AK, Smithson S, Trembath RC, Deshpande C, Simpson MA. De novo mutations in MLL cause Wiedemann-Steiner syndrome. Am J Hum Genet. 2012 Aug 10;91(2):358-64. doi: 10.1016/j.ajhg.2012.06.008. Epub, 2012 Jul 12. PMID:22795537 doi:10.1016/j.ajhg.2012.06.008↑ Adler HT, Chinery R, Wu DY, Kussick SJ, Payne JM, Fornace AJ Jr, Tkachuk DC. Leukemic HRX fusion proteins inhibit GADD34-induced apoptosis and associate with  the GADD34 and hSNF5/INI1 proteins. Mol Cell Biol. 1999 Oct;19(10):7050-60. PMID:10490642 ↑ Adler HT, Chinery R, Wu DY, Kussick SJ, Payne JM, Fornace AJ Jr, Tkachuk DC. Leukemic HRX fusion proteins inhibit GADD34-induced apoptosis and associate with  the GADD34 and hSNF5/INI1 proteins. Mol Cell Biol. 1999 Oct;19(10):7050-60. PMID:10490642 ↑ Patel A, Dharmarajan V, Vought VE, Cosgrove MS. On the mechanism of multiple lysine methylation by the human mixed lineage leukemia protein-1 (MLL1) core complex. J Biol Chem. 2009 Sep 4;284(36):24242-56. Epub 2009 Jun 25. PMID:19556245 doi:M109.014498↑ Guelman S, Kozuka K, Mao Y, Pham V, Solloway MJ, Wang J, Wu J, Lill JR, Zha J. The double-histone-acetyltransferase complex ATAC is essential for mammalian development. Mol Cell Biol. 2009 Mar;29(5):1176-88. doi: 10.1128/MCB.01599-08. Epub 2008 Dec, 22. PMID:19103755 doi:10.1128/MCB.01599-08↑ Cai Y, Jin J, Swanson SK, Cole MD, Choi SH, Florens L, Washburn MP, Conaway JW, Conaway RC. Subunit composition and substrate specificity of a MOF-containing histone acetyltransferase distinct from the male-specific lethal (MSL) complex. J Biol Chem. 2010 Feb 12;285(7):4268-72. doi: 10.1074/jbc.C109.087981. Epub 2009 , Dec 14. PMID:20018852 doi:10.1074/jbc.C109.087981↑ Han Z, Guo L, Wang H, Shen Y, Deng XW, Chai J. Structural basis for the specific recognition of methylated histone H3 lysine 4 by the WD-40 protein WDR5. Mol Cell. 2006 Apr 7;22(1):137-44. PMID:16600877 doi:10.1016/j.molcel.2006.03.018↑ Couture JF, Collazo E, Trievel RC. Molecular recognition of histone H3 by the WD40 protein WDR5. Nat Struct Mol Biol. 2006 Aug;13(8):698-703. Epub 2006 Jul 9. PMID:16829960 doi:10.1038/nsmb1116↑ Adler HT, Chinery R, Wu DY, Kussick SJ, Payne JM, Fornace AJ Jr, Tkachuk DC. Leukemic HRX fusion proteins inhibit GADD34-induced apoptosis and associate with  the GADD34 and hSNF5/INI1 proteins. Mol Cell Biol. 1999 Oct;19(10):7050-60. PMID:10490642 ↑ Nakamura T, Mori T, Tada S, Krajewski W, Rozovskaia T, Wassell R, Dubois G, Mazo A, Croce CM, Canaani E. ALL-1 is a histone methyltransferase that assembles a supercomplex of proteins involved in transcriptional regulation. Mol Cell. 2002 Nov;10(5):1119-28. PMID:12453419 ↑ Dou Y, Milne TA, Tackett AJ, Smith ER, Fukuda A, Wysocka J, Allis CD, Chait BT, Hess JL, Roeder RG. Physical association and coordinate function of the H3 K4 methyltransferase MLL1  and the H4 K16 acetyltransferase MOF. Cell. 2005 Jun 17;121(6):873-85. PMID:15960975 doi:10.1016/j.cell.2005.04.031↑ Patel A, Dharmarajan V, Vought VE, Cosgrove MS. On the mechanism of multiple lysine methylation by the human mixed lineage leukemia protein-1 (MLL1) core complex. J Biol Chem. 2009 Sep 4;284(36):24242-56. Epub 2009 Jun 25. PMID:19556245 doi:M109.014498↑ Patel A, Dharmarajan V, Vought VE, Cosgrove MS. On the mechanism of multiple lysine methylation by the human mixed lineage leukemia protein-1 (MLL1) core complex. J Biol Chem. 2009 Sep 4;284(36):24242-56. Epub 2009 Jun 25. PMID:19556245 doi:M109.014498↑ Avdic V, Zhang P, Lanouette S, Groulx A, Tremblay V, Brunzelle J, Couture JF. Structural and biochemical insights into MLL1 core complex assembly. Structure. 2011 Jan 12;19(1):101-8. PMID:21220120 doi:10.1016/j.str.2010.09.022
 
 |