Detecting mistranslation in yeast expressing tRNA variants

Mistranslation, the mis-incorporation of an amino acid not specified by the “standard” genetic code, occurs in all cells. tRNA variants that increase mistranslation arise spontaneously and engineered tRNAs can achieve mistranslation frequencies approaching 10% in yeast and bacteria. The goal of this study was to detect mistranslation from two different tRNA variants. The first variant, tRNA-Pro-G3:U70, has a mutation in its acceptor stem creating a G3:U70 base pair which is the key identity element for the alanine tRNA synthetase. This tRNA should be charged with alanine and mis-incorporate alanine at proline codons. The second variant, tRNA-Ser-UCU,G26A, is a serine tRNA with an arginine anticodon and a G26A secondary mutation to dampen function and prevent lethal levels of mistranslation. This tRNA should mis-incorporate serine at arginine codons.