MCB Accepts, published online ahead of print on 2 November 2009

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Lin, C. A. Articles by True, H. L. PubMed PubMed Citation Articles by Lin, C. A. Articles by True, H. L.

 Previous Article  |  Next Article 

Mol. Cell. Biol. doi:10.1128/MCB.00754-09
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

The Sua5 protein is essential for normal translational regulation in yeast

Changyi A. Lin, Steven R. Ellis, and Heather L. True^*

Department of Cell Biology and Physiology, Washington University School of Medicine, Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA

^* To whom correspondence should be addressed. Email: Heather.True{at}cellbiology.wustl.edu.

The anticodon stem loop of tRNAs requires extensive post-transcriptional 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 (t⁶A₃₇) of tRNAs that recognize ANN codons. Located adjacent and 3' to the anticodon, t⁶A₃₇ 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 t⁶A₃₇. Sua5 was originally identified in a screen by virtue of its ability to affect expression from an aberrant upstream AUG 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 (IRES)-mediated mechanism. This study reveals a critical role for Sua5 and the t⁶A₃₇ modification in translational fidelity.