Global translational impacts of the loss of the tRNA modification t6A in yeast
Authors:Patrick C. Thiaville1,2,3,4, Rachel Legendre4, Diego Rojas-Benítez5, Agnès Baudin-Baillieu4, Isabelle Hatin4, Guilhem Chalancon6, Alvaro Glavic5, Olivier Namy4, Valérie de Crécy-Lagard1,3
doi: 10.15698/mic2016.01.473
Volume 3, pp. 29 to 45, published 18/12/2015.
1 Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA.
2 Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL 32610, USA.
3 University of Florida Genetics Institute, University of Florida, Gainesville, FL 32610, USA.
4 Institut de Biologie Intégrative de la Cellule (I2BC), CEA, CNRS, Université Paris-Sud, Bâtiment 400, 91400 Orsay, France.
5 Centro de Regulación del Genoma. Facultad de Ciencias – Universidad de Chile, Santiago, Chile.
6 Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom.
Keywords:
t6A, tRNA, ribosome profiling, translation, modified nucleosides.
Corresponding Author(s):
Conflict of interest statement:
The authors declare no conflict of interest.
Please cite this article as:
Patrick C. Thiaville, Rachel Legendre, Diego Rojas-Benítez, Agnès Baudin-Baillieu, Isabelle Hatin, Guilhem Chalancon, Alvaro Glavic, Olivier Namy, Valérie de Crécy-Lagard (2015). Global translational impacts of the loss of the tRNA modification t6A in yeast. Microbial Cell 3(1): 29-45. doi: 10.15698/mic2016.01.473
© 2015 Thiaville et al. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.
Abstract:
The universal tRNA modification t6A is found at position 37 of nearly all tRNAs decoding ANN codons. The absence of t6A37 leads to severe growth defects in baker’s yeast, phenotypes similar to those caused by defects in mcm5s2U34 synthesis. Mutants in mcm5s2U34 can be suppressed by overexpression of tRNALysUUU, but we show t6A phenotypes could not be suppressed by expressing any individual ANN decoding tRNA, and t6A and mcm5s2U are not determinants for each other’s formation. Our results suggest that t6A deficiency, like mcm5s2U deficiency, leads to protein folding defects, and show that the absence of t6A led to stress sensitivities (heat, ethanol, salt) and sensitivity to TOR pathway inhibitors. Additionally, L-homoserine suppressed the slow growth phenotype seen in t6A-deficient strains, and proteins aggregates and Advanced Glycation End-products (AGEs) were increased in the mutants. The global consequences on translation caused by t6A absence were examined by ribosome profiling. Interestingly, the absence of t6A did not lead to global translation defects, but did increase translation initiation at upstream non-AUG codons and increased frame-shifting in specific genes. Analysis of codon occupancy rates suggests that one of the major roles of t6A is to homogenize the process of elongation by slowing the elongation rate at codons decoded by high abundance tRNAs and I34:C3 pairs while increasing the elongation rate of rare tRNAs and G34:U3 pairs. This work reveals that the consequences of t6A absence are complex and multilayered and has set the stage to elucidate the molecular basis of the observed phenotypes.