Fig. 4

Examples of uORF-mediated translational regulation. GCN4: well-studied case in which high translation of uORFs that are proximal to the CDS has an inhibitory effect on the translation of the main protein in normal conditions. Decreased rate of translation of these uORF during stress allows the protein to be expressed. The plot shows a profile of Ribo-Seq reads in normal and stress conditions, Scer. Oxi dataset. FC CDS stress vs normal RNA-Seq: 0.84; FC CDS stress vs normal Ribo-Seq: 3.51. fi1: functional analog to GCN4 in S. pombe. The Fil1 mRNA shows changes in ribosome density in several uORFs, suggesting that it could also be regulated by uORFs. Data shown is from the Spom.N- experiment. FC CDS stress vs normal RNA-Seq: 1.01; FC CDS stress vs normal Ribo-Seq: 3.02. ubi4: the S. cerevisiae polyubiquitin gene Ubi4 has been involved in the response to different types of stress. Here we could observe that the translation of Ubi4 was strongly activated during nitrogen depletion in S. pombe and that this was accompanied by a strong decrease in the translation of two uORFs in the 5’UTR (decrease in the number of Ribo-Seq mapped reads 10–20 fold). FC CDS stress vs normal RNA-Seq: 2.07; FC CDS stress vs normal Ribo-Seq: 5.64. tif5: the translation initiation factor 5 is required for the formation of the functional 80S initiation complex and was strongly inhibited in nitrogen starvation conditions in S. pombe. An uORF in the 5’UTR showed much higher translation levels in stress compared to normal conditions, representing a possible example in which uORF translation contributes to specific repression of certain mRNAs during stress. FC CDS stress vs normal RNA-Seq: 0.37; FC CDS stress vs normal Ribo-Seq: 0.06