title: Dual Targeting of the Protein Methyltransferase PrmA Contributes to Both Chloroplastic and Mitochondrial Ribosomal Protein L11 Methylation in Arabidopsis.
abstract: Methylation of ribosomal proteins has long been described in prokaryotes and eukaryotes, but our knowledge about the enzymes responsible for these modifications in plants is scarce. The bacterial protein methyltransferase PrmA catalyzes the trimethylation of ribosomal protein L11 (RPL11) at three distinct sites. The role of these modifications is still unknown. Here, we show that PrmA from Arabidopsis thaliana (AtPrmA) is dually targeted to chloroplasts and mitochondria. Mass spectrometry and enzymatic assays indicated that the enzyme methylates RPL11 in plasto- and mitoribosomes in vivo. We determined that the Arabidopsis and Escherichia coli PrmA enzymes share similar product specificity, making trimethylated residues, but, despite an evolutionary relationship, display a difference in substrate site specificity. In contrast to the bacterial enzyme that trimethylates the ε-amino group of two lysine residues and the N-terminal α-amino group, AtPrmA methylates only one lysine in the MAFCK(D/E)(F/Y)NA motif of plastidial and mitochondrial RPL11. The plant enzyme possibly methylates the N-terminus of plastidial RPL11, whereas mitochondrial RPL11 is N-α-acetylated by an unknown acetyltransferase. Lastly, we found that an Arabidopsis prma-null mutant is viable in standard environmental conditions and no molecular defect could be associated with a lack of RPL11 methylation in leaf chloroplasts or mitochondria. However, the conservation of PrmA during the evolution of photosynthetic eukaryotes together with the location of methylated residues at the binding site of translation factors to ribosomes suggests that RPL11 methylation in plant organelles could be involved, in combination with other post-translational modifications, in optimizing ribosome function.
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Meryl
authors.initials: M
authors.lastname: Mazzoleni
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Figuet
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Martin-Laffon
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Morgane
authors.initials: M
authors.lastname: Mininno
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Annabelle
authors.initials: A
authors.lastname: Gilgen
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Leroux
authors.affiliation: Université Grenoble Alpes, F-38041 Grenoble, France CEA, iRTSV, Biologie à Grande Echelle, F-38054 Grenoble, France INSERM, U1038, F-38054 Grenoble, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Brugière
authors.affiliation: Université Grenoble Alpes, F-38041 Grenoble, France CEA, iRTSV, Biologie à Grande Echelle, F-38054 Grenoble, France INSERM, U1038, F-38054 Grenoble, France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Tardif
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Alban
authors.affiliation: Université Grenoble Alpes, Laboratoire de Physiologie Cellulaire & Végétale, F-38041 Grenoble, France CNRS, UMR5168, F-38054 Grenoble, France CEA, iRTSV, Laboratoire de Physiologie Cellulaire & Végétale, F-38054 Grenoble, France INRA, USC1359, F-38054 Grenoble, France stephane.ravanel@cea.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ravanel
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology*; D005816:Genetic Complementation Test; D018525:Germination; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010788:Photosynthesis; D010802:Phylogeny; D014176:Protein Biosynthesis; D021381:Protein Transport; D012269:Ribosomal Proteins / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D024101:Mitochondrial Proteins; D010455:Peptides; C000608244:RPL11 protein, Arabidopsis; D012269:Ribosomal Proteins; D008780:Methyltransferases; C000608243:PrmA protein, Arabidopsis
keywords: Chloroplast; Dual targeting; Methylation; Mitochondrion; Post-translational modification; Ribosomes