title: Structural insights of the specificity and catalysis of a viral histone H3 lysine 27 methyltransferase.
abstract: SET domain lysine methyltransferases are known to catalyze site and state-specific methylation of lysine residues in histones that is fundamental in epigenetic regulation of gene activation and silencing in eukaryotic organisms. Here we report the three-dimensional solution structure of the SET domain histone lysine methyltransferase (vSET) from Paramecium bursaria chlorella virus 1 bound to cofactor S-adenosyl-L-homocysteine and a histone H3 peptide containing mono-methylated lysine 27. The dimeric structure, mimicking an enzyme/cofactor/substrate complex, yields the structural basis of the substrate specificity and methylation multiplicity of the enzyme. Our results from mutagenesis and enzyme kinetics analyses argue that a general base mechanism is less likely for lysine methylation by SET domains; and that the only invariant active site residue tyrosine 105 in vSET facilitates methyl transfer from cofactor to the substrate lysine by aligning intermolecular interactions in the lysine access channel of the enzyme.
authors.affiliation: Department of Molecular Physiology and Biophysics, Mount Sinai School of Medicine, New York University, NY 10029, USA.
authors.forename: Chengmin
authors.initials: C
authors.lastname: Qian
authors.forename: Xueqi
authors.initials: X
authors.lastname: Wang
authors.forename: Karishma
authors.initials: K
authors.lastname: Manzur
authors.lastname: Sachchidanand
authors.forename: Amjad
authors.initials: A
authors.lastname: Farooq
authors.forename: Lei
authors.initials: L
authors.lastname: Zeng
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Ming-Ming
authors.initials: MM
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004252:DNA Mutational Analysis; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism*; D008745:Methylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D010247:Paramecium / Q000821:virology; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017862:Phycodnaviridae / Q000201:enzymology*; D011496:Protein Methyltransferases; D020836:Protein Structure, Quaternary; D012435:S-Adenosylhomocysteine / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D006657:Histones; D010455:Peptides; D014764:Viral Proteins; D012435:S-Adenosylhomocysteine; D000076983:Histone Methyltransferases; D011496:Protein Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D008239:Lysine