2ri3
Crystal structure of the 3-MBT repeats from human L3MBTL1 with N358Q point mutation
Structural highlights
FunctionLMBL1_HUMAN Polycomb group (PcG) protein that specifically recognizes and binds mono- and dimethyllysine residues on target proteins, therey acting as a 'reader' of a network of post-translational modifications. PcG proteins maintain the transcriptionally repressive state of genes: acts as a chromatin compaction factor by recognizing and binding mono- and dimethylated histone H1b/HIST1H1E at 'Lys-26' (H1bK26me1 and H1bK26me2) and histone H4 at 'Lys-20' (H4K20me1 and H4K20me2), leading to condense chromatin and repress transcription. Recognizes and binds p53/TP53 monomethylated at 'Lys-382', leading to repress p53/TP53-target genes. Also recognizes and binds RB1/RB monomethylated at 'Lys-860'. Participates in the ETV6-mediated repression. Probably plays a role in cell proliferation. Overexpression induces multinucleated cells, suggesting that it is required to accomplish normal mitosis.[1] [2] [3] [4] 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 PubMedHuman L3MBTL1, which contains three malignant brain tumor (MBT) repeats, binds monomethylated and dimethylated lysines, but not trimethylated lysines, in several histone sequence contexts. In crystal structures of L3MBTL1 complexes, the monomethyl- and dimethyllysines insert into a narrow and deep cavity of aromatic residue-lined pocket 2, while a proline ring inserts into shallower pocket 1. We have also engineered a single Y to E substitution within the aromatic cage of the BPTF PHD finger, resulting in a reversal of binding preference from trimethyl- to dimethyllysine in an H3K4 sequence context. In both the "cavity insertion" (L3MBTL1) and "surface groove" (PHD finger) modes of methyllysine recognition, a carboxylate group both hydrogen bonds and ion pairs to the methylammonium proton. Our structural and binding studies of these two modules provide insights into the molecular principles governing the decoding of lysine methylation states, thereby highlighting a methylation state-specific layer of histone mark readout impacting on epigenetic regulation. Structural basis for lower lysine methylation state-specific readout by MBT repeats of L3MBTL1 and an engineered PHD finger.,Li H, Fischle W, Wang W, Duncan EM, Liang L, Murakami-Ishibe S, Allis CD, Patel DJ Mol Cell. 2007 Nov 30;28(4):677-91. PMID:18042461[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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