title: Selenium-based S-adenosylmethionine analog reveals the mammalian seven-beta-strand methyltransferase METTL10 to be an EF1A1 lysine methyltransferase.
abstract: Lysine methylation has been extensively studied in histones, where it has been shown to provide specific epigenetic marks for the regulation of gene expression; however, the molecular mechanism and physiological function of lysine methylation in proteins other than histones remains to be fully addressed. To better understand the substrate diversity of lysine methylation, S-adenosylmethionine (SAM) derivatives with alkyne-moieties have been synthesized. A selenium-based SAM analog, propargylic Se-adenosyl-l-selenomethionine (ProSeAM), has a wide spectrum of reactivity against various lysine methyltransferases (KMTs) with sufficient stability to support enzymatic reactions in vitro. By using ProSeAM as a chemical probe for lysine methylation, we identified substrates for two seven-beta-strand KMTs, METTL21A and METTL10, on a proteomic scale in mammalian cells. METTL21A has been characterized as a heat shock protein (HSP)-70 methyltransferase. Mammalian METTL10 remains functionally uncharacterized, although its ortholog in yeast, See1, has been shown to methylate the translation elongation factor eEF1A. By using ProSeAM-mediated alkylation followed by purification and quantitative MS analysis, we confirmed that METTL21A labels HSP70 family proteins. Furthermore, we demonstrated that METTL10 also methylates the eukaryotic elongation factor EF1A1 in mammalian cells. Subsequent biochemical characterization revealed that METTL10 specifically trimethylates EF1A1 at lysine 318 and that siRNA-mediated knockdown of METTL10 decreases EF1A1 methylation levels in vivo. Thus, our study emphasizes the utility of the synthetic cofactor ProSeAM as a chemical probe for the identification of non-histone substrates of KMTs.
authors.affiliation: Cellular Memory Laboratory, RIKEN, Wako, Japan.
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Shimazu
authors.affiliation: Synthetic Organic Chemistry Laboratory, RIKEN, Wako, Japan.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Barjau
authors.affiliation: Synthetic Organic Chemistry Laboratory, RIKEN, Wako, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sohtome
authors.affiliation: Synthetic Organic Chemistry Laboratory, RIKEN, Wako, Japan.
authors.forename: Mikiko
authors.initials: M
authors.lastname: Sodeoka
authors.affiliation: Cellular Memory Laboratory, RIKEN, Wako, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shinkai
mesh_terms: D000818:Animals; D057809:HEK293 Cells; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008856:Microscopy, Fluorescence; D012436:S-Adenosylmethionine / Q000031:analogs & derivatives* / Q000737:chemistry*; D012643:Selenium / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D012436:S-Adenosylmethionine; D011495:Histone-Lysine N-Methyltransferase; D012643:Selenium