Serine Acts as a Metabolic Signal for the Transcriptional Control of Photorespiration-Related Genes in Arabidopsis  

Abstract

Photosynthetic carbon assimilation including photorespiration is dynamically regulated during the day/night cycle. This includes transcriptional regulation, such as the light induction of corresponding genes, but little is known about the contribution of photorespiratory metabolites to the regulation of gene expression. Here, we examined diurnal changes in the levels of photorespiratory metabolites, of enzymes of the photorespiratory carbon cycle, and of corresponding transcripts in wild-type plants of Arabidopsis (Arabidopsis thaliana) and in a mutant with altered photorespiratory flux due to the absence of the peroxisomal enzyme Hydroxypyruvate Reductase1 (HPR1). Metabolomics of the wild type showed that the relative amounts of most metabolites involved in photorespiration increased after the onset of light, exhibited maxima at the end of the day, and decreased during the night. In accordance with those findings, both the amounts of messenger RNAs encoding photorespiratory enzymes and the respective protein contents showed a comparable accumulation pattern. Deletion of HPR1 did not significantly alter most of the metabolite patterns relative to wild-type plants; only serine accumulated to a constitutively elevated amount in this mutant. In contrast, the hpr1 mutation resulted in considerable deregulation of the transcription of photorespiration-related genes. This transcriptional deregulation could also be induced by the external application of L-serine but not glycine to the Arabidopsis wild type, suggesting that serine acts as a metabolic signal for the transcriptional regulation of photorespiration, particularly in the glycine-to-serine interconversion reactions.

Virus-Induced Alterations in Primary Metabolism Modulate Susceptibility toTobacco rattle virusin Arabidopsis

“…It would also be of interest to test how transcriptomic changes in protein metabolism are reflected in the rate of protein synthesis of the cell. In our study, the accumulation of Ser and Gly to high levels at early time points of infection may be related to the transcriptional repression of photorespiration that we observed (Timm et al, 2013). Indeed, higher accumulation of the photorespiratory intermediates Ser and Gly is known to cause a feedback deregulation of photorespiration-related genes (Timm et al, 2013).…”

“…In our study, the accumulation of Ser and Gly to high levels at early time points of infection may be related to the transcriptional repression of photorespiration that we observed (Timm et al, 2013). Indeed, higher accumulation of the photorespiratory intermediates Ser and Gly is known to cause a feedback deregulation of photorespiration-related genes (Timm et al, 2013). The accumulation of several other amino acids could reveal antiviral responses in infected leaves.…”

Functional Characterization of the Plastidial 3-Phosphoglycerate Dehydrogenase Family in Arabidopsis

“…Thus, Ser could well be the link connecting primary metabolism with the control of cell cycle progression in specific cell types. This could be related to the role of Ser in transcriptional regulation (Timm et al, 2013).…”

Identification of the light-independent phosphoserine pathway as an additional source of serine in the cyanobacterium Synechocystis sp. PCC 6803

“…Serine is involved in the biosynthesis of purines and pyrimidines, and serves as an important precursor for other essential compounds, including the amino acids glycine and cysteine or phospholipids (Walton & Woolhouse, 1986). Recently, it has been shown that serine also acts as a metabolic signal for the transcriptional regulation of photorespiratory genes in the model plant Arabidopsis thaliana (Timm et al, 2013).…”