The sucrose regulated transcription factor bZIP11 affects amino acid metabolism by regulating the expression of ASPARAGINE SYNTHETASE1 and PROLINE DEHYDROGENASE2

Abstract

SummaryTranslation of the transcription factor bZIP11 is repressed by sucrose in a process that involves a highly conserved peptide encoded by the 5¢ leaders of bZIP11 and other plant basic region leucine zipper (bZip) genes. It is likely that a specific signaling pathway operating at physiological sucrose concentrations controls metabolism via a feedback mechanism. In this paper bZIP11 target processes are identified using transiently increased nuclear bZIP11 levels and genome-wide expression analysis. bZIP11 affects the expression of hundreds of genes with proposed functions in biochemical pathways and signal transduction. The expression levels of approximately 80% of the genes tested are not affected by bZIP11 promoter-mediated overexpression of bZIP11. This suggests that <20% of the identified genes appear to be physiologically relevant targets of bZIP11. ASPARAGINE SYNTHETASE1 and PROLINE DEHYDROGENASE2 are among the rapidly activated bZIP11 targets, whose induction is independent of protein translation. Transient expression experiments in Arabidopsis protoplasts show that the bZIP11-dependent activation of the ASPARAGINE SYNTHETASE1 gene is dependent on a G-box element present in the promoter. Increased bZIP11 expression leads to decreased proline and increased phenylalanine levels. A model is proposed in which sugar signals control amino acid levels via the bZIP11 transcription factor.

The Arabidopsis transcription factor bZIP11 activates auxin-mediated transcription by recruiting the histone acetylation machinery

“…As bZIP11 and -44 showed the strongest activation potential on the GH3.3 promoter in protoplasts, we focused on these TFs applying stably transformed gain-of-function plants. Because constitutive ectopic expression of bZIP11-related bZIPs strongly interferes with plant growth 44,45 , we expressed the bZIPs as HA-tagged versions using a b-estradiol (Est)-inducible expression system (XVE) 46 . Quantitative real-time PCR (qRT-PCR) analysis revealed that GH3.3 induction correlated with an early increase of the bZIP11 regulator, which becomes detectable by immunoblot after 2 h of Est treatment (Fig.…”

“…The bZIP factors studied here belong to the C/S1 network of bZIP TFs that have been demonstrated to form specific heterodimers and to be involved in reprogramming of metabolism in response to low energy stress 45,[54][55][56] . Hence, it is tempting to speculate, that the described regulatory mechanism is used to adjust auxin-mediated responses to the energy status of the cell.…”

Cis-regulatory elements used to control gene expression in plants

“…Guerrero-González et al (2014) confirmed the negative effect of the AtPAO3 uORF on GUS expression, which can be overcome by exogenous polyamines supplementation. A model proposed and tested on A. thaliana by Hanson et al (2008) confirms that the constitutive expression of the bZIP11, known to be repressed by sucrose through the uORF, inhibits the production of proline and stimulates the production of phenylalanine.…”

Gene and Metabolite Regulatory Network Analysis of Early Developing Fruit Tissues Highlights New Candidate Genes for the Control of Tomato Fruit Composition and Development

“…Transcription factors belonging to different families Falkenberg et al, 2008;Gutiérrez et al, 2008;Hanson et al, 2008;Luo et al, 2008) were already shown to regulate different plant metabolite content. In our study, one of the most striking examples of a correlation between a metabolite and a transcription factor concerns Gln, which is directly correlated to both a MYB and a bZIP transcription factor (Fig.…”