Multiple transcripts regulate glucose-triggered mRNA decay of the lactate transporter JEN1 from Saccharomyces cerevisiae

The Saccharomyces cerevisiae JEN1 gene encoding the lactate transporter undergoes strong catabolic repression at both transcriptional and post-transcriptional levels. JEN1 mRNA decay is greatly accelerated upon the addition of a pulse of glucose, fructose or mannose to induced cell cultures. Mapping of the 5´UTRs and 3´UTRs of JEN1 transcripts revealed multiple transcription start-sites located at position -51, +391 or +972, depending on the cell culture conditions. The presence of the JEN1(+391) transcript correlated with rapid glucose-triggered mRNA degradation of the JEN1(-51) transcript, whereas when the small transcript started at position +972, the JEN1(-51) mRNA turnover rate was unaffected. Overexpressed JEN1(+391) transcript accelerated JEN1(-51) mRNA decay in all conditions tested but was not translated. We propose that the JEN1(+391) transcript may have a ‘‘sensor-like’’ function, regulating glucose-triggered degradation of JEN1(-51) protein-coding mRNA.Fundação para a Ciência e a Tecnologia (FCT) - Programa Operacional "Ciência, Tecnologia, Inovação (POCTI) - POCTI/BIO/38106/2001 (Eixo 2, Medida 2.3, QCAIII-FEDER), BD/15737/98, SFRH/BPD/9432/2002. Deutsche Forschungsgemeinschaft (SFB 579)