title: Ribosome biogenesis factor Tsr3 is the aminocarboxypropyl transferase responsible for 18S rRNA hypermodification in yeast and humans.
abstract: The chemically most complex modification in eukaryotic rRNA is the conserved hypermodified nucleotide N1-methyl-N3-aminocarboxypropyl-pseudouridine (m(1)acp(3)Ψ) located next to the P-site tRNA on the small subunit 18S rRNA. While S-adenosylmethionine was identified as the source of the aminocarboxypropyl (acp) group more than 40 years ago the enzyme catalyzing the acp transfer remained elusive. Here we identify the cytoplasmic ribosome biogenesis protein Tsr3 as the responsible enzyme in yeast and human cells. In functionally impaired Tsr3-mutants, a reduced level of acp modification directly correlates with increased 20S pre-rRNA accumulation. The crystal structure of archaeal Tsr3 homologs revealed the same fold as in SPOUT-class RNA-methyltransferases but a distinct SAM binding mode. This unique SAM binding mode explains why Tsr3 transfers the acp and not the methyl group of SAM to its substrate. Structurally, Tsr3 therefore represents a novel class of acp transferase enzymes.
authors.affiliation: Institute for Molecular Biosciences, Goethe University, Frankfurt/M, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Meyer
authors.affiliation: Institute for Molecular Biosciences, Goethe University, Frankfurt/M, Germany Center of Biomolecular Magnetic Resonance, Goethe University, Frankfurt/M, Germany.
authors.forename: Jan Philip
authors.initials: JP
authors.lastname: Wurm
authors.affiliation: RNA Molecular Biology & Center for Microscopy and Molecular Imaging, Fonds National de la Recherche Scientifique (F.R.S./FNRS), Université Libre de Bruxelles (ULB).
authors.forename: Sunny
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Institute for Molecular Biosciences, Goethe University, Frankfurt/M, Germany Center of Biomolecular Magnetic Resonance, Goethe University, Frankfurt/M, Germany.
authors.forename: Carina
authors.initials: C
authors.lastname: Immer
authors.affiliation: Institute of Biochemistry, Goethe University, Frankfurt/M, Germany.
authors.forename: Denys
authors.initials: D
authors.lastname: Pogoryelov
authors.affiliation: Institute for Molecular Biosciences, Goethe University, Frankfurt/M, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Kötter
authors.affiliation: RNA Molecular Biology & Center for Microscopy and Molecular Imaging, Fonds National de la Recherche Scientifique (F.R.S./FNRS), Université Libre de Bruxelles (ULB).
authors.forename: Denis L J
authors.initials: DL
authors.lastname: Lafontaine
authors.affiliation: Institute for Molecular Biosciences, Goethe University, Frankfurt/M, Germany Center of Biomolecular Magnetic Resonance, Goethe University, Frankfurt/M, Germany woehnert@bio.uni-frankfurt.de.
authors.forename: Jens
authors.initials: J
authors.lastname: Wöhnert
authors.affiliation: Institute for Molecular Biosciences, Goethe University, Frankfurt/M, Germany entian@bio.uni-frankfurt.de.
authors.forename: Karl-Dieter
authors.initials: KD
authors.lastname: Entian
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000502:physiology*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D045325:HCT116 Cells; D006801:Humans; D006860:Hydrogen Bonding; D055029:Inverted Repeat Sequences; D008958:Models, Molecular; D011485:Protein Binding; D012323:RNA Processing, Post-Transcriptional; D012337:RNA, Ribosomal, 18S / Q000096:biosynthesis* / Q000737:chemistry; D012436:S-Adenosylmethionine / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D012337:RNA, Ribosomal, 18S; D012436:S-Adenosylmethionine; D019883:Alkyl and Aryl Transferases; C000620960:TSR3 protein, S cerevisiae; C000620959:TSR3 protein, human