title: RNA-methyltransferase TrmA is a dual-specific enzyme responsible for C5-methylation of uridine in both tmRNA and tRNA.
abstract: In bacteria, trans-translation rescues stalled ribosomes by the combined action of tmRNA (transfer-mRNA) and its associated protein SmpB. The tmRNA 5' and 3' ends fold into a tRNA-like domain (TLD), which shares structural and functional similarities with tRNAs. As in tRNAs, the UUC sequence of the T-arm of the TLD is post-transcriptionally modified to m (5)UψC. In tRNAs of gram-negative bacteria, formation of m (5)U is catalyzed by the SAM-dependent methyltransferase TrmA, while formation of m (5)U at two different positions in rRNA is catalyzed by distinct site-specific methyltransferases RlmC and RlmD. Here, we show that m (5)U formation in tmRNAs is exclusively due to TrmA and should be considered as a dual-specific enzyme. The evidence comes from the lack of m (5)U in purified tmRNA or TLD variants recovered from an Escherichia coli mutant strain deleted of the trmA gene. Detection of m (5)U in RNA was performed by NMR analysis.
authors.affiliation: CNRS - UMR 8015, Laboratoire de Cristallographie et RMN Biologiques, Faculté de Pharmacie, Paris, France.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Ranaei-Siadat
authors.forename: Céline
authors.initials: C
authors.lastname: Fabret
authors.forename: Bili
authors.initials: B
authors.lastname: Seijo
authors.forename: Frédéric
authors.initials: F
authors.lastname: Dardel
authors.forename: Henri
authors.initials: H
authors.lastname: Grosjean
authors.forename: Sylvie
authors.initials: S
authors.lastname: Nonin-Lecomte
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D064251:Multifunctional Enzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009690:Nucleic Acid Conformation; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014529:Uridine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012359:tRNA Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D064251:Multifunctional Enzymes; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; C520618:TrmA protein, E coli; C096222:tmRNA; D012343:RNA, Transfer; D008780:Methyltransferases; D012359:tRNA Methyltransferases; D014529:Uridine
keywords: NMR; TrmA; methylation; methyltransferase; post-transcriptional modification; t-RNA like domain (TLD); tmRNA