The role of the 5′ untranslated region (UTR) in glucose‐dependent mRNA decay

When S. cerevisiae are grown with glucose, SDH2 mRNA encoding the iron protein of the succinate dehydrogenase complex is unstable and present at low level. In yeast grown without glucose, SDH2 mRNA is stable and its level rises. Addition of glucose to a glucose-limited culture causes the SDH2 mRNA level to fall rapidly with a half-life of approximately 5-7 min. Previously the 5'UTR of the mRNA of SDH2 was shown to be necessary and sufficient to destabilize it in glucose (Lombardo et al., 1992). We now show that the SDH1 and SUC2 5'UTRs are capable of conferring glucose-sensitive mRNA instability. We also examine how changes in the SDH2 5'UTR affect glucose-triggered degradation. Finally, we show that changes in mRNA stability are correlated with changes in translational efficiency for these transcripts.