4x8p | pdb_00004x8p
Crystal structure of Ash2L SPRY domain in complex with RbBP5
Structural highlights
Function[ASH2L_HUMAN] Component of the Set1/Ash2 histone methyltransferase (HMT) complex, a complex that specifically methylates 'Lys-4' of histone H3, but not if the neighboring 'Lys-9' residue is already methylated. As part of the MLL1/MLL complex it is involved in methylation and dimethylation at 'Lys-4' of histone H3. May function as a transcriptional regulator. May play a role in hematopoiesis.[1] [2] [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.[3] Publication Abstract from PubMedThe methyltransferase activity of the trithorax group (TrxG) protein MLL1 found within its COMPASS (complex associated with SET1)-like complex is allosterically regulated by a four-subunit complex composed of WDR5, RbBP5, Ash2L, and DPY30 (also referred to as WRAD). We report structural evidence showing that in WRAD, a concave surface of the Ash2L SPIa and ryanodine receptor (SPRY) domain binds to a cluster of acidic residues, referred to as the D/E box, in RbBP5. Mutational analysis shows that residues forming the Ash2L/RbBP5 interface are important for heterodimer formation, stimulation of MLL1 catalytic activity, and erythroid cell terminal differentiation. We also demonstrate that a phosphorylation switch on RbBP5 stimulates WRAD complex formation and significantly increases KMT2 (lysine [K] methyltransferase 2) enzyme methylation rates. Overall, our findings provide structural insights into the assembly of the WRAD complex and point to a novel regulatory mechanism controlling the activity of the KMT2/COMPASS family of lysine methyltransferases. A phosphorylation switch on RbBP5 regulates histone H3 Lys4 methylation.,Zhang P, Chaturvedi CP, Tremblay V, Cramet M, Brunzelle JS, Skiniotis G, Brand M, Shilatifard A, Couture JF Genes Dev. 2015 Jan 15;29(2):123-8. doi: 10.1101/gad.254870.114. PMID:25593305[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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