Global translational impacts of the loss of the tRNA modification t 6 A in yeast
The universal tRNA modification t A is found at position 37 of nearly all tRNAs decoding ANN codons. The absence of t A leads to severe growth defects in baker's yeast, phenotypes similar to those caused by defects in mcm s U synthesis. Mutants in mcm s U can be suppressed by overexpression of...
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Published in | Microbial cell Vol. 3; no. 1; p. 29 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Austria
01.01.2016
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Subjects | |
Online Access | Get full text |
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Summary: | The universal tRNA modification t
A is found at position 37 of nearly all tRNAs decoding ANN codons. The absence of t
A
leads to severe growth defects in baker's yeast, phenotypes similar to those caused by defects in mcm
s
U
synthesis. Mutants in mcm
s
U
can be suppressed by overexpression of tRNA
, but we show t
A phenotypes could not be suppressed by expressing any individual ANN decoding tRNA, and t
A and mcm
s
U are not determinants for each other's formation. Our results suggest that t
A deficiency, like mcm
s
U deficiency, leads to protein folding defects, and show that the absence of t
A led to stress sensitivities (heat, ethanol, salt) and sensitivity to TOR pathway inhibitors. Additionally, L-homoserine suppressed the slow growth phenotype seen in t
A-deficient strains, and proteins aggregates and Advanced Glycation End-products (AGEs) were increased in the mutants. The global consequences on translation caused by t
A absence were examined by ribosome profiling. Interestingly, the absence of t
A 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 t
A is to homogenize the process of elongation by slowing the elongation rate at codons decoded by high abundance tRNAs and I
:C
pairs while increasing the elongation rate of rare tRNAs and G
:U
pairs. This work reveals that the consequences of t
A absence are complex and multilayered and has set the stage to elucidate the molecular basis of the observed phenotypes. |
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ISSN: | 2311-2638 2311-2638 |