3kmt

Crystal structure of vSET/SAH/H3 ternary complex

spinqualitylabelsall models 3kmt, resolution 1.78Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3kmt is a 6 chain structure with sequence from Homo sapiens and Paramecium bursaria Chlorella virus 1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.78Å Ligands: MLZ, SAH Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function O41094_PBCV1 Publication Abstract from PubMed Histone modifications are regarded as the most indispensible phenomena in epigenetics. Of these modifications, lysine methylation is of the greatest complexity and importance as site- and state-specific lysine methylation exerts a plethora of effects on chromatin structure and gene transcription. Notably, paramecium bursaria chlorella viruses encode a conserved SET domain methyltransferase, termed vSET, that functions to suppress host transcription by methylating histone H3 at lysine 27 (H3K27), a mark for eukaryotic gene silencing. Unlike mammalian lysine methyltransferases (KMTs), vSET functions only as a dimer, but the underlying mechanism has remained elusive. In this study, we demonstrate that dimeric vSET operates with negative cooperativity between the two active sites and engages in H3K27 methylation one site at a time. New atomic structures of vSET in the free form and a ternary complex with S-adenosyl homocysteine and a histone H3 peptide and biochemical analyses reveal the molecular origin for the negative cooperativity and explain the substrate specificity of H3K27 methyltransferases. Our study suggests a "walking" mechanism, by which vSET acts all by itself to globally methylate host H3K27, which is accomplished by the mammalian EZH2 KMT only in the context of the Polycomb repressive complex. Dimerization of a viral SET protein endows its function.,Wei H, Zhou MM Proc Natl Acad Sci U S A. 2010 Oct 26;107(43):18433-8. Epub 2010 Oct 11. PMID:20937900 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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