The yeast rapid tRNA decay pathway competes with elongation factor 1A for substrate tRNAs and acts on tRNAs lacking one or more of several modifications
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, New York 14642, USA
Abstract
The structural and functional integrity of tRNA is crucial for translation. In the yeast Saccharomyces cerevisiae, certain aberrant pre-tRNA species are subject to nuclear surveillance, leading to 3′ exonucleolytic degradation, and certain mature tRNA species are subject to rapid tRNA decay (RTD) if they are appropriately hypomodified or bear specific destabilizing mutations, leading to 5′-3′ exonucleolytic degradation by Rat1 and Xrn1. Thus, trm8-Δ trm4-Δ strains are temperature sensitive due to lack of m7G46 and m5C and the consequent RTD of tRNAVal(AAC), and tan1-Δ trm44-Δ strains are temperature sensitive due to lack of ac4C12 and Um44 and the consequent RTD of tRNASer(CGA) and tRNASer(UGA). It is unknown how the RTD pathway interacts with translation and other cellular processes, and how generally this pathway acts on hypomodified tRNAs. We provide evidence here that elongation factor 1A (EF-1A) competes with the RTD pathway for substrate tRNAs, since its overexpression suppresses the tRNA degradation and the growth defect of strains subject to RTD, whereas reduced levels of EF-1A have the opposite effect. We also provide evidence that RTD acts on a variety of tRNAs lacking one or more different modifications, since trm1-Δ trm4-Δ mutants are subject to RTD of tRNASer(CGA) and tRNASer(UGA) due to lack of m2,2G26 and m5C, and since trm8-Δ, tan1-Δ, and trm1-Δ single mutants are each subject to RTD. These results demonstrate that RTD interacts with the translation machinery and acts widely on hypomodified tRNAs.
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↵3 Corresponding author
E-mail eric_phizicky{at}urmc.rochester.edu
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Article published online ahead of print. Article and publication date are at http://www.rnajournal.org/cgi/doi/10.1261/rna.033654.112.
- Received April 4, 2012.
- Accepted July 3, 2012.
- Copyright © 2012 RNA Society
