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.
Johansson
Marcus J O
MJ
Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden.
Esberg
Anders
A
Huang
Bo
B
Björk
Glenn R
GR
Byström
Anders S
AS
D000926:Anticodon / Q000737:chemistry* / Q000235:genetics*; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D005800:Genes, Fungal; D010957:Plasmids / Q000235:genetics; D014176:Protein Biosynthesis; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D046249:Transfer RNA Aminoacylation; D014529:Uridine / Q000737:chemistry*
D000926:Anticodon; D003062:Codon; D012331:RNA, Fungal; D012343:RNA, Transfer; D014529:Uridine