Reprogramming of metabolism by the Arabidopsis thaliana bZIP11 transcription factor

Abstract

The Arabidopsis bZIP11 transcription factor is known to regulate amino acid metabolism, and transcriptomic analysis suggests that bZIP11 has a broader regulatory effects in metabolism. Moreover, sucrose controls its translation via its uORF and all the available evidences point to the fact that bZIP11 participates in the molecular network downstream of SnRK1 in response to low carbon conditions. Furthermore, the heterodimerization capability between bZIP11 and C group bZIP transcription factors diversify its function in regulating gene expression. In this thesis, the studies employed omic techniques including transcriptomics and metabolomics analyses and detailed molecular ! and biochemical analyses to undermine the function of bZIP11 in gene regulation and its possible role in sugar signaling. Remarkably we found that besides amino acid metabolism, bZIP11 reprograms sugar metabolism as well, by regulating the corresponding metabolic genes. In detail, bZIP11 regulates the biosynthesis of raffinose and degradation of myoinositol and trehalose. The capability of turning over signaling molecules in carbon metabolism including trehalose 6-phosphate and trehalose positions bZIP11 in the network sensing sugar availability. The transcriptomic analysis confirmed that bZIP11 induces a set of carbon starvation genes, which implies it possible role under carbon starvation conditions again. The further anal! ysis suggested that C group bZIP transcription factor bZIP10 plays an important role in augmenting the transcription activity of bZIP11. For instance there is synergistic effect in inducing the trehalose 6-phosphate phosphatase encoding genes and also trehalase. The regulation of bZIP11 in trehalose 6-phosphate and trehalose degradation genes including TPP5, TPP6 and Trehalase 1 gives rise to trehalose resistant phenotype in bZIP11 over expressing seedlings. The transcriptomic analysis in seedlings in response to trehalose feeding emerges that trehalose and trehalose 6-phosphate are powerful molecules in regulating global gene expressions. Interestingly, S1 group bZIP transcription factors including bZIP11 are trehalose responsive genes. Thus, all the fact points to that bZIP11 participates in sugar signaling network by interacting with trehalose 6-phosphate metabolism