title: Human METTL20 is a mitochondrial lysine methyltransferase that targets the β subunit of electron transfer flavoprotein (ETFβ) and modulates its activity.
abstract: Proteins are frequently modified by post-translational methylation of lysine residues, catalyzed by S-adenosylmethionine-dependent lysine methyltransferases (KMTs). Lysine methylation of histone proteins has been extensively studied, but it has recently become evident that methylation of non-histone proteins is also abundant and important. The human methyltransferase METTL20 belongs to a group of 10 established and putative human KMTs. We here found METTL20 to be associated with mitochondria and determined that recombinant METTL20 methylated a single protein in extracts from human cells. Using an methyltransferase activity-based purification scheme, we identified the β-subunit of the mitochondrially localized electron transfer flavoprotein (ETFβ) as the substrate of METTL20. Furthermore, METTL20 was found to specifically methylate two adjacent lysine residues, Lys(200) and Lys(203), in ETFβ both in vitro and in cells. Interestingly, the residues methylated by METTL20 partially overlap with the so-called "recognition loop" in ETFβ, which has been shown to mediate its interaction with various dehydrogenases. Accordingly, we found that METTL20-mediated methylation of ETFβ in vitro reduced its ability to receive electrons from the medium chain acyl-CoA dehydrogenase and the glutaryl-CoA dehydrogenase. In conclusion, the present study establishes METTL20 as the first human KMT localized to mitochondria and suggests that it may regulate cellular metabolism through modulating the interaction between its substrate ETFβ and dehydrogenases. Based on the previous naming of similar enzymes, we suggest the renaming of human METTL20 to ETFβ-KMT.
authors.affiliation: From the Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, 0316, Norway.
authors.forename: Jędrzej
authors.initials: J
authors.lastname: Małecki
authors.affiliation: From the Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, 0316, Norway.
authors.forename: Angela Y Y
authors.initials: AY
authors.lastname: Ho
authors.affiliation: From the Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, 0316, Norway.
authors.forename: Anders
authors.initials: A
authors.lastname: Moen
authors.affiliation: From the Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, 0316, Norway.
authors.forename: Helge-André
authors.initials: HA
authors.lastname: Dahl
authors.affiliation: From the Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, 0316, Norway pal.falnes@ibv.uio.no.
authors.forename: Pål Ø
authors.initials: PØ
authors.lastname: Falnes
mesh_terms: D044944:Acyl-CoA Dehydrogenases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D044927:Electron-Transferring Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D050770:Glutaryl-CoA Dehydrogenase / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000737:chemistry / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: C500319:ETFB protein, human; D044927:Electron-Transferring Flavoproteins; D024101:Mitochondrial Proteins; D021122:Protein Subunits; D011994:Recombinant Proteins; D012436:S-Adenosylmethionine; D044944:Acyl-CoA Dehydrogenases; D050770:Glutaryl-CoA Dehydrogenase; C000594659:ETFBKMT protein, human; D008780:Methyltransferases; D008239:Lysine
keywords: Electron Transfer Flavoprotein; Enzyme Catalysis; Mitochondrial Metabolism; Post-translational Modification (PTM); Protein Methylation; Protein Targeting