Translational enhancement conferred by the 3' untranslated region of a transcript encoding a group 6 late embryogenesis abundant protein

To assure an efficient protein production under stress conditions, some transcripts are modulated at the translational level. To better understand the control of protein production under stress, we analysed the enhancing effect of the 3' untranslated region (UTR) of the water deficit responsive gene PvLEA6 from Phaseolus vulgaris on the regulation of its expression. GUS activity and transcript loading on polysomes were analysed using Arabidopsis transgenic plants with constructs containing GUS open reading frame fused to wild type or mutated PvLEA6-3'UTR, driven by the PvLEA6 promoter, grown under optimal or stress conditions. The effect of the PvLEA6-3'UTR on gene transcription and transcript stability was discarded. We demonstrated that the PvLEA6-3' UTR allows preferential polysome loading of the GUS reporter transcript under water deficit. The effect of this region on protein synthesis was also supported by in vitro translation data. Particular conserved motifs in this region responsible for translation stimulation were identified. Specific interaction of the 3' UTR with cellular protein(s) was shown. Our data support a specific role of PvLEA6-3' UTR leading to efficient protein synthesis and hence a competent response under water deficit and suggest the participation of mRNA binding proteins in translational enhancement of the PvLEA6 mRNA.

Automated summary

The PvLEA6-3'UTR enhances the loading of GUS reporter transcript on polysomes under water deficit conditions, promoting efficient protein synthesis. Specific conserved motifs in this region stimulate translation, while a specific interaction with cellular proteins was observed.