Project description:Secondary metabolites play a key role in coordinating ecology and defense strategies of plants. Diversity of these metabolites arise by conjugation of core structures with diverse chemical moieties, such as sugars in glycosylation. Active pools of phytohormones, including those involved in plant stress response are also regulated by glycosylation. While, much is known about the enzymes involved in glycosylation, we know little about their regulation or coordination with other processes. We characterized the flavonoid pathway transcription factor, TRANSPARENT TESTA 8 (TT8) in Arabidopsis thaliana, using an integrative omics strategy. This approach provides a systems level understanding of the cellular machinery that is used to generate metabolite diversity by glycosylation. Metabolomics analysis of TT8 loss-of-function and inducible overexpression lines showed that TT8 coordinates glycosylation of not only flavonoids, but also nucleotides, thus, implicating TT8 in regulating pools of activated nucleotide sugars. Transcriptome and promoter network analyses revealed that TT8 regulome included sugar transporters, proteins involved in sugar binding and sequestration, and a number of carbohydrate active enzymes. Importantly, TT8 affects stress response, along with brassinosteroid and jasmonic acid biosynthesis, by directly binding to the promoters of key genes of these processes. This combined effect on metabolites glycosylation and stress hormones by TT8 inducible overexpression led to significant increase in tolerance towards multiple abiotic and biotic stresses. Conversely, loss of TT8 leads to increased sensitivity to these stresses. Thus, the transcription factor TT8 is an integrator of secondary metabolism and stress response. These findings provide novel approaches to improve broad-spectrum stress tolerance. Gene expression analysis for 6-day old Arabidopsis thaliana seedling were performed for TT8 loss-of-function line, tt8-3 (in Ws background), and its wild type background control, Ws. Two independent biological replicates for each line were hybridized onto two slides of Agilent SurePrint G2 Agilent Arabidopsis V4 (4x44K), with each slide having two technical replicates for each line. Contributors: Amit Rai, Shivshankar Umashankar, Megha, Lim Boon Kiat, Johanan Aow Shao Bing, Sanjay Swarup.

Project description:Streptococcus pneumoniae is a strictly fermentative human pathogen that relies on carbohydrate metabolism to generate energy for growth. The nasopharynx colonised by the bacterium is poor in free sugars, but mucosa lining glycans can provide a source of sugar. In blood and inflamed tissues glucose is the prevailing sugar. As a result during progression from colonisation to disease S. pneumoniae has to cope with a pronounced shift in carbohydrate nature and availability. Thus, we set out to assess the pneumococcal response to sugars found in glycans and the influence of glucose (Glc) on this response at the transcriptional, physiological and metabolic levels. Galactose (Gal), N-acetylglucosamine (GlcNAc) and mannose (Man) affected the expression of 8 to 14% of the genes covering cellular functions including central carbon metabolism and virulence. The pattern of end-products as monitored by in vivo 13C-NMR is in good agreement with the fermentation profiles during growth, while the pools of phosphorylated metabolites are consistent with the type of fermentation observed (homolactic vs. mixed) and regulation at the metabolic level. Furthermore, the accumulation of -Gal6P and Man6P indicate metabolic bottlenecks in the metabolism of Gal and Man, respectively. Glc added to cells actively metabolizing other sugar(s)was readily consumed and elicited a metabolic shift towards a homolactic profile. The transcriptional response to Glc was large (over 5% of the genome). In central carbon metabolism (most represented category), Glc exerted mostly negative regulation. The smallest response was observed on a sugar mix, suggesting that exposure to varied sugars improves the fitness of S. pneumoniae. The expression of classical virulence factors was negatively controlled by Glc in a sugar-dependent manner. Overall, our results shed new light on the link between carbohydrate metabolism, adaptation to host niches and virulence. Two conditions with the same strain (D39), including a dye swap

Dataset Information

Coordinate Regulation of Metabolite Glycosylation and Stress Hormone Biosynthesis by TT8 in Arabidopsis

Publications

Coordinate Regulation of Metabolite Glycosylation and Stress Hormone Biosynthesis by TT8 in Arabidopsis.

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