Abstract
Regulation of gene expression through translational control is common in many organisms. The Arabidopsis (Arabidopsis thaliana) transcription factor bZIP11 is translational repressed in response to sucrose (Suc), resulting in Suc-regulated changes in amino acid metabolism. The 5' leader of the bZIP11 mRNA harbors several upstream open reading frames (uORFs), of which the second uORF is well conserved among bZIP11 homologous genes. The uORF2 element encodes a Suc control peptide (SC-peptide) of 28 residues that is sufficient for imposing Suc-induced repression of translation (SIRT) on a heterologous mRNA. Detailed analysis of the SC-peptide suggests that it functions as an attenuator peptide. Results suggest that the SC-peptide inhibits bZIP11 translation in response to high Suc levels by stalling the ribosome on the mRNA. The conserved noncanonical AUG contexts of bZIP11 uORFs allow inefficient translational initiation of the uORF, resulting in translation initiation of the scanning ribosome at the AUG codon of the bZIP11 main ORF. The results presented show that Suc-dependent signaling mediates differential translation of mRNAs containing SC-peptides encoding uORFs.
Highlights
Regulation of gene expression through translational control is common in many organisms
The transcription activation potential of bZIP11 and related proteins is enhanced by the Snf1-related kinases (SnRKs) KIN10 and KIN11 that regulate responses to stress resulting from nutrient deprivation (Baena-Gonzalez et al, 2007)
It is shown that the SC-peptide is required and sufficient for Suc-induced repression of translation (SIRT), and a model is proposed where Suc in combination with the SC-peptide leads to ribosome stalling and translational inhibition of the main ORF
Summary
Regulation of gene expression through translational control is common in many organisms. Results suggest that the SCpeptide inhibits bZIP11 translation in response to high Suc levels by stalling the ribosome on the mRNA. The results presented show that Suc-dependent signaling mediates differential translation of mRNAs containing SC-peptides encoding uORFs. Developmental and physiological processes in organisms depend on regulation of gene expression. The uORF of the Arabidopsis SAC51 gene (encoding a basic helixloop-helix-type transcription factor) was shown to inhibit translation of the main ORF (Imai et al, 2006). Sucrose-Regulated Translation on the second uORF in the bZIP11 5# leader (uORF2) This uORF encodes a conserved Suc control peptide (SC-peptide) present in four other Arabidopsis bZip genes (bZIP1, bZIP2, bZIP44, and bZIP53) and in many other bZip genes from other species (Wiese et al, 2004, 2005). It is shown that the SC-peptide is required and sufficient for SIRT, and a model is proposed where Suc in combination with the SC-peptide leads to ribosome stalling and translational inhibition of the main ORF
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