title: U2552 methylation at the ribosomal A-site is a negative modulator of translational accuracy.
abstract: We have recently identified RrmJ, the first encoded protein of the rrmJ-ftsH heat shock operon, as being the Um(2552) methyltransferase of 23S rRNA, and reported that rrmJ-deficient strains exhibit growth defects, reduced translation rates and reduced stability of 70S ribosomes. U2552 is an ubiquitously methylated residue. It belongs to the A loop of 23S RNA which is an essential component of the ribosome peptidyltransferase centre and interacts directly with aminoacyl(A)-site tRNA. In the present study, we show that a lack of U2552 methylation, obtained in rrmJ-deficient mutants, results in a decrease in programmed +1 and -1 translational frameshifing and a decrease in readthrough of UAA and UGA stop codons. The increased translational accuracy of rrmJ-deficient strains suggests that the interaction between aminoacyl-tRNA and U2552 is important for selection of the correct tRNA at the ribosomal A site, and supports the idea that translational accuracy in vivo is optimal rather than maximal, thus pointing to the participation of recoding events in the normal cell physiology.
authors.affiliation: Molecules de Stress Institut Jacques Monod, Université Paris 7, 2, Place Jussieu, 75005 Paris, France.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Widerak
authors.forename: Renée
authors.initials: R
authors.lastname: Kern
authors.forename: Abderrahim
authors.initials: A
authors.lastname: Malki
authors.forename: Gilbert
authors.initials: G
authors.lastname: Richarme
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D018388:Codon, Terminator / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D018965:Frameshifting, Ribosomal / Q000235:genetics / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics* / Q000502:physiology; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D018388:Codon, Terminator; D029968:Escherichia coli Proteins; D012338:RNA, Ribosomal, 23S; D012346:RNA, Transfer, Amino Acyl; D008780:Methyltransferases; C102247:rlmE protein, E coli