Aminoacyl-tRNA synthetase mutant
In vivo misreading
Springer Online Journal Archives 1860-2000
Summary The hts1.1 temperature-sensitive histidinyl-tRNA synthetase mutation enables Saccharomyces cerevisiae to be starved for His-tRNAHis by upshift to the non-permissive temperature of 38°C. If yeast behaves similarly to bacterial and mammalian cells, this lack of His-tRNAHis should greatly enhance misreading at histidine codons (CAU/CAC) by Gln-tRNAGln, resulting in substitution of the neutral amino acid glutamine in place of histidine, a basic amino acid. Such misreading causes the isoelectric point (pI) of proteins to shift to lower values, and is readily detectable as “stuttering” on two-dimensional (2D) protein gels. By gel analysis of pulse-labelled proteins of hts1.1 yeast cells that were overexpressing phosphoglycerate kinase (PGK), our study sought to detect this specific translational error in PGK protein. It was not detected by this relatively sensitive technique, indicating that missense errors due to glutamine insertion at histidine codons do not occur in yeast at the readily-detectable level found in bacterial and mammalian cells.
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