Yeast Cells Cannot Incorporate Queuine into Their tRNA

Abstract

The compound known as queuine has been found in the tRNAs of virtually all animals, plants, and bacteria. It is absent in yeast tRNA. Mice have a dietary requirement for queuine and are dependent either on their diet or intestinal flora for this hypermodified purine. We tested the possibility that yeast were like higher mammals in that they could not synthesize queuine but would incorporate it into their tRNA if it was made available to them. This report shows that this is not the case and that yeast cells not only cannot synthesize queuine but they cannot incorporate exogenous queuine into their tRNA.