Probing the genetic code with Leucine tRNA variants
Abstract
Mistranslation is an error in protein synthesis whereby the amino acids specified by the genetic code are misplaced by others in the growing polypeptide chain. The anticodon of tRNALeu can be altered allowing for the misincorporation of leucine at non-leucine codons. Observing the effect of tRNALeu variants on the viability of yeast and mammalian cells will provide information on their ability to cause mistranslation and potential relationship to genetic diseases. To explore this, a random pool of tRNALeu anticodonvariants was expressed in Saccharomyces cerevisiae. Furthermore, three mutant tRNALeu already sequenced from humans were expressed in murine Neuro 2A blastoma cells. There was slow growth in yeast when tRNALeu with proline (NGG) and arginine (GCG) anticodons were expressed. In N2a cells tRNALeu GAA lowered protein synthesis while tRNALeuCCA increased it. The effect of each tRNALeu anticodon variant varied depended on the anticodon with no obvious correlation to known biological factors.