2kyu
From Proteopedia
The solution structure of the PHD3 finger of MLL
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[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.[5] [6] [7] [8] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe mixed lineage leukemia (MLL) gene plays a critical role in epigenetic regulation of gene expression and is a frequent target of chromosomal translocations leading to leukemia. MLL plant homeodomain 3 (PHD3) is lost in all MLL translocation products, and reinsertion of PHD3 into MLL fusion proteins abrogates their transforming activity. PHD3 has been shown to interact with the RNA-recognition motif (RRM) domain of human nuclear Cyclophilin33 (CYP33). Here, we show that CYP33 mediates downregulation of the expression of MLL target genes HOXC8, HOXA9, CDKN1B, and C-MYC, in a proline isomerase-dependent manner. This downregulation correlates with the reduction of trimethylated lysine 4 of histone H3 (H3K4me3) and histone H3 acetylation. We have structurally characterized both the PHD3 and CYP33 RRM domains and analyzed their binding to one another. The PHD3 domain binds H3K4me3 (preferentially) and the CYP33 RRM domain at distinct sites. Our binding data show that binding of H3K4me3 to PHD3 and binding of the CYP33 RRM domain to PHD3 are mutually inhibitory, implying that PHD3 is a molecular switch for the transition between activation and repression of target genes. To explore the possible mechanism of CYP33/PHD3-mediated repression, we have analyzed the CYP33 proline isomerase activity on various H3 and H4 peptides and shown selectivity for two sites in H3. Our results provide a possible mechanism for the MLL PHD3 domain to act as a switch between activation and repression. The PHD3 domain of MLL acts as a CYP33-regulated switch between MLL-mediated activation and repression .,Park S, Osmers U, Raman G, Schwantes RH, Diaz MO, Bushweller JH Biochemistry. 2010 Aug 10;49(31):6576-86. PMID:20677832[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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