Eukaryotic wobble uridine modifications promote a functionally redundant decoding system.

The translational decoding properties of tRNAs are modulated by naturally occurring modifications of their nucleosides. Uridines located at the wobble position (nucleoside 34 [U(34)]) in eukaryotic cytoplasmic tRNAs often harbor a 5-methoxycarbonylmethyl (mcm(5)) or a 5-carbamoylmethyl (ncm(5)) side chain and sometimes an additional 2-thio (s(2)) or 2'-O-methyl group. Although a ...
variety of models explaining the role of these modifications have been put forth, their in vivo functions have not been defined. In this study, we utilized recently characterized modification-deficient Saccharomyces cerevisiae cells to test the wobble rules in vivo. We show that mcm(5) and ncm(5) side chains promote decoding of G-ending codons and that concurrent mcm(5) and s(2) groups improve reading of both A- and G-ending codons. Moreover, the observation that the mcm(5)U(34)- and some ncm(5)U(34)-containing tRNAs efficiently read G-ending codons challenges the notion that eukaryotes do not use U-G wobbling.
Mesh Terms:
Anticodon, Base Sequence, Codon, Genes, Fungal, Plasmids, Protein Biosynthesis, RNA, Fungal, RNA, Transfer, Saccharomyces cerevisiae, Transfer RNA Aminoacylation, Uridine
Mol. Cell. Biol.
Date: May. 01, 2008
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