6v63

SETD3 WT in Complex with an Actin Peptide with His73 Replaced with Glutamine

spinqualitylabelsall models 6v63, resolution 2.02Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6v63 is a 4 chain structure with sequence from Human. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, EDO, GOL, SAH Gene: SETD3, C14orf154 (HUMAN) Activity: Protein-histidine N-methyltransferase, with EC number 2.1.1.85 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SETD3_HUMAN] Histone methyltransferase that methylates 'Lys-36' of histone H3 (H3K36me). H3 'Lys-36' methylation represents a specific tag for epigenetic transcriptional activation (By similarity). Publication Abstract from PubMed Most characterized SET domain (SETD) proteins are protein lysine methyltransferases, but SETD3 was recently demonstrated to be a protein (i.e.actin) histidine-N3methyltransferase. Human SETD3 shares a high structural homology with two known protein lysine methyltransferases-human SETD6 and the plant LSMT-but differs in the residues constituting the active site. In the SETD3 active site, Asn-255 engages in a unique hydrogen-bonding interaction with the target histidine of actin that likely contributes to its >1300-fold greater catalytic efficiency (kcat/Km) on histidine than on lysine. Here, we engineered active-site variants to switch the SETD3 target specificity from histidine to lysine. Substitution of Asn-255 with phenylalanine (N255F), together with substitution of Trp-273 with alanine (W273A), generated an active site mimicking that of known lysine methyltransferases. The doubly substituted SETD3 variant exhibited a 13-fold preference for lysine over histidine. We show, by means of X-ray crystallography, that the two target nitrogen atoms-the N3atom of histidine and the terminal e-amino nitrogen of lysine-occupy the same position and point towards and are within a short distance of the incoming methyl group of SAM for a direct methyl transfer during catalysis. In contrast, SETD3 and its Asn-255 substituted derivatives did not methylate glutamine (another potentially methylated amino acid). However, the glutamine-containing peptide competed with the substrate peptide, and glutamine bound in the active site, but too far away from SAM to be methylated. Our results provide insight into the structural parameters defining the target amino acid specificity of SET enzymes. An engineered variant of SETD3 methyltransferase alters target specificity from histidine to lysine methylation.,Dai S, Horton JR, Wilkinson AW, Gozani O, Zhang X, Cheng X J Biol Chem. 2020 Jan 7. pii: RA119.012319. doi: 10.1074/jbc.RA119.012319. PMID:31911441 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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