title: S-adenosyl methionine is necessary for inhibition of the methyltransferase G9a by the lysine 9 to methionine mutation on histone H3.
abstract: Lysine to methionine (K-to-M) mutations in genes encoding histone H3 are thought to drive a subset of pediatric brain and bone cancers. These high-frequency K-to-M mutations occur at sites of methylation on histone H3, and tumors containing the mutant histones exhibit a global loss of specific histone methylation marks. Previous studies showed that K-to-M mutant histones, also known as oncohistones, are potent orthosteric inhibitors of specific Su(var)3-9, Enhancer-of-zeste, Trithorax (SET) domain methyltransferases. However, the biochemical and biophysical details of the interaction between K-to-M mutant histones and the respective SET domain methyltransferases are currently unknown. Here, we use the histone H3K9-directed methyltransferase G9a as a model to explore the mechanism of inhibition by K-to-M oncohistones. X-ray cocrystal structures revealed that the K9M residue of histone H3 occupies the active site cavity of G9a, and kinetic analysis indicates competitive inhibition of G9a by histone H3K9M. Additionally, we find that the cofactor S-adenosyl methionine (SAM) is necessary for stable interaction between G9a and H3K9M histone. Consistent with the formation of a ternary complex, we find that the inhibitory peptide is uncompetitive with regard to SAM. These data and others indicate that K-to-M oncohistones promote global loss of specific lysine methylation through sequestration and inhibition of SAM-bound SET domain methyltransferases.
authors.affiliation: Constellation Pharmaceuticals, Cambridge, MA 02142;
authors.forename: Hariharan
authors.initials: H
authors.lastname: Jayaram
authors.affiliation: Wisconsin Institute of Discovery, University of Wisconsin, Madison, WI 53715; Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53715;
authors.forename: Dominik
authors.initials: D
authors.lastname: Hoelper
authors.affiliation: Wisconsin Institute of Discovery, University of Wisconsin, Madison, WI 53715; Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53715;
authors.forename: Siddhant U
authors.initials: SU
authors.lastname: Jain
authors.affiliation: Constellation Pharmaceuticals, Cambridge, MA 02142;
authors.forename: Nico
authors.initials: N
authors.lastname: Cantone
authors.affiliation: Wisconsin Institute of Discovery, University of Wisconsin, Madison, WI 53715; Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53715;
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Lundgren
authors.affiliation: Constellation Pharmaceuticals, Cambridge, MA 02142;
authors.forename: Florence
authors.initials: F
authors.lastname: Poy
authors.affiliation: Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065 alliscd@rockefeller.edu Richard.Cummings@constellationpharma.com Steve.Bellon@constellationpharma.com plewis@discovery.wisc.edu.
authors.forename: C David
authors.initials: CD
authors.lastname: Allis
authors.affiliation: Constellation Pharmaceuticals, Cambridge, MA 02142; alliscd@rockefeller.edu Richard.Cummings@constellationpharma.com Steve.Bellon@constellationpharma.com plewis@discovery.wisc.edu.
authors.forename: Richard
authors.initials: R
authors.lastname: Cummings
authors.affiliation: Constellation Pharmaceuticals, Cambridge, MA 02142; alliscd@rockefeller.edu Richard.Cummings@constellationpharma.com Steve.Bellon@constellationpharma.com plewis@discovery.wisc.edu.
authors.forename: Steven
authors.initials: S
authors.lastname: Bellon
authors.affiliation: Wisconsin Institute of Discovery, University of Wisconsin, Madison, WI 53715; Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53715; alliscd@rockefeller.edu Richard.Cummings@constellationpharma.com Steve.Bellon@constellationpharma.com plewis@discovery.wisc.edu.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Lewis
mesh_terms: D018360:Crystallography, X-Ray; D011495:Histone-Lysine N-Methyltransferase / Q000037:antagonists & inhibitors* / Q000235:genetics; D006657:Histones / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D008239:Lysine / Q000737:chemistry / Q000235:genetics*; D008715:Methionine / Q000737:chemistry / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D010446:Peptide Fragments / Q000737:chemistry; D012436:S-Adenosylmethionine / Q000494:pharmacology*; D013379:Substrate Specificity
chemical_list: D006657:Histones; D010446:Peptide Fragments; D012436:S-Adenosylmethionine; D008715:Methionine; D011495:Histone-Lysine N-Methyltransferase; D008239:Lysine
keywords: EHMT2; G9a; H3K9me3; K to M; oncohistone