U2552 methylation at the ribosomal A-site is a negative modulator of translational accuracy.
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.[1]References
- U2552 methylation at the ribosomal A-site is a negative modulator of translational accuracy. Widerak, M., Kern, R., Malki, A., Richarme, G. Gene (2005) [Pubmed]
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