Control of 5-FOA and 5-FU resistance by Saccharomyces cerevisiae YJL055W.

In a URA3/5-FOA-based dosage-suppressor screen, we isolated a plasmid containing the little-characterized ORF YJL055W. Further analysis showed that this gene did not suppress the mutation of interest. Instead, overexpression of Yjl055Wp directly suppressed the non-viability of URA3(+) cells in the presence of 5-FOA. Overexpression of Yjl055Wp also suppressed the lethality induced by 5-FU, but deletion of YJL055W had no detectable effect on resistance to either 5-FOA or 5-FU. Based on these observations and a previous report that a yjl055wDelta mutant has increased sensitivity to purine-analogue mutagens, we suggest that Yjl055Wp may function in one of several pathways for the detoxification of base analogues. However, its precise mechanism of action remains unknown.