期刊
RNA BIOLOGY
卷 15, 期 4-5, 页码 567-575出版社
TAYLOR & FRANCIS INC
DOI: 10.1080/15476286.2017.1379645
关键词
Aminoacyl-tRNA synthetase; cell stress; genetic code; translation; tRNA
资金
- Natural Sciences and Engineering Research Council of Canada [RGPIN-2015-04394, RGPIN 04282-2014]
- Canada Foundation for Innovation [229917]
- Ontario Research Fund [229917]
- Canada Research Chairs [950-229917]
- Canadian Cancer Society Research Institute innovation grant [704324]
High-fidelity translation and a strictly accurate proteome were originally assumed as essential to life and cellular viability. Yet recent studies in bacteria and eukaryotic model organisms suggest that proteome-wide mistranslation can provide selective advantages and is tolerated in the cell at higher levels than previously thought (one error in 6.9 x 10(-4) in yeast) with a limited impact on phenotype. Previously, we selected a tRNA(Pro) containing a single mutation that induces mistranslation with alanine at proline codons in yeast. Yeast tolerate the mistranslation by inducing a heat-shock response and through the action of the proteasome. Here we found a homologous human tRNA(Pro) (G3:U70) mutant that is not aminoacylated with proline, but is an efficient alanine acceptor. In live human cells, we visualized mistranslation using a green fluorescent protein reporter that fluoresces in response to mistranslation at proline codons. In agreement with measurements in yeast, quantitation based on the GFP reporter suggested a mistranslation rate of up to 2-5% in HEK 293 cells. Our findings suggest a stress-dependent phenomenon where mistranslation levels increased during nutrient starvation. Human cells did not mount a detectable heat-shock response and tolerated this level of mistranslation without apparent impact on cell viability. Because humans encode approximate to 600 tRNA genes and the natural population has greater tRNA sequence diversity than previously appreciated, our data also demonstrate a cell-based screen with the potential to elucidate mutations in tRNAs that may contribute to or alleviate disease.
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