The Sua5 protein is essential for normal translational regulation in yeast.
The anticodon stem-loop of tRNAs requires extensive posttranscriptional modifications in order to maintain structure and stabilize the codon-anticodon interaction. These modifications also play a role in accommodating wobble, allowing a limited pool of tRNAs to recognize degenerate codons. Of particular interest is the formation of a threonylcarbamoyl group on adenosine 37 (t(6)A(37)) of tRNAs that recognize ANN codons. Located adjacent and 3' to the anticodon, t(6)A(37) is a conserved modification that is critical for reading frame maintenance. Recently, the highly conserved YrdC/Sua5 family of proteins was shown to be required for the formation of t(6)A(37). Sua5 was originally identified in a screen by virtue of its ability to affect expression from an aberrant upstream AUG codon in the cyc1 transcript. Together, these findings implicate Sua5 in protein translation at the level of codon recognition. Here, we show that Sua5 is critical for normal translation. The loss of SUA5 causes increased leaky scanning through AUG codons, +1 frameshifting, and nonsense suppression. In addition, the loss of SUA5 amplifies the 20S RNA virus found in Saccharomyces cerevisiae, possibly through an internal ribosome entry site-mediated mechanism. This study reveals a critical role for Sua5 and the t(6)A(37) modification in translational fidelity.
Lin
Changyi A
CA
Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
Ellis
Steven R
SR
True
Heather L
HL
D050976:Basic-Leucine Zipper Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D018387:Codon, Initiator; D018388:Codon, Terminator; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D018965:Frameshifting, Ribosomal; D016366:Open Reading Frames; D014176:Protein Biosynthesis; D012328:RNA Viruses / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D012367:RNA, Viral / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
D050976:Basic-Leucine Zipper Transcription Factors; D018387:Codon, Initiator; D018388:Codon, Terminator; D004268:DNA-Binding Proteins; C501391:GCN4 protein, S cerevisiae; D012367:RNA, Viral; C541142:SUA5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012343:RNA, Transfer