Biology subjects

Schwender, J.

Publications and source records attributed to Schwender, J..

4 recordsLinked to original sources

bioRxiv2025

Trehalose 6-phosphate activates Target of Rapamycin in plants

Coordinating carbon availability with growth is a fundamental challenge in plants. Target of Rapamycin (TOR) promotes cell growth and is activated by sugars, but the underlying molecular mechanism has remained elusive. Here, we identify trehalose 6-phosphate (T6P), a sucrose-derived metabolite, as the key signal linking carbon to TOR activity. In Arabidopsis and Brassica napus, T6P stimulates cell growth via TOR and is required for sucrose-induced TOR activation. We show immunoprecipitates using anti-TOR antibodies contain catalytically active TOR in addition to the catalytically active SnRK1 energy sensor kinase. In vitro experiments show that, SnRK11, the catalytic subunit of SnRK1 suppresses TOR activity, and T6P reverses this inhibition in a dose-dependent manner, providing biochemical evidence that T6P activates TOR by suppressing SnRK1. This work thus establishes a direct sucrose-T6P-SnRK1-TOR signaling axis that couples carbon availability to plant growth.

plant biology↗

bioRxiv2025

Resolving cofactor imbalance in triacylglycerol biosynthesis in oilseeds through glycolytic shunts: a modeling study

During seed development, carbohydrates are rapidly converted into triacylglycerols (TAGs), with glycolysis and the oxidative pentose phosphate pathway (OPPP) traditionally considered key sources of acetyl-CoA, ATP, NADH, and NADPH for fatty acid synthesis. However, how these classical pathways integrate into an overall stoichiometrically balanced conversion of sugars to TAGs remains unclear. Previous biochemical and isotope-tracing studies in oilseeds across species have revealed that glycolysis is partially bypassed by alternative routes involving ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) and NADPH-dependent malic enzyme (NADPH-ME). The role of these glycolytic shunts in the overall conversion of carbohydrates to TAG is not fully resolved. Here, we evaluate a minimal stoichiometric model for the carbohydrate-to-TAG conversion that satisfies complete cofactor balancing. Conversion solely through glycolysis and OPPP leads to NADH overproduction and cofactor imbalance. Balanced scenarios require inclusion of the malate shunt, the oxidative RubisCO shunt, or an NADPH-producing glyceraldehyde 3-phosphate dehydrogenase variant. All balanced routes also necessitate active mitochondrial oxidative phosphorylation to convert excess NADH to ATP. Applying a large-scale model of central metabolism in developing Brassica napus seeds, I further predict that glycolytic bypass usage increases in parallel with seed oil content, supporting their role in enabling high lipid biosynthetic fluxes under physiological constraints. HighlightConventional carbohydrate-to-triacylglycerol conversion is cofactor-imbalanced; flux balance analysis shows glycolytic bypasses help correct this, enabling higher biosynthetic rates.

plant biology↗

bioRxiv2020

An Expanded Role for WRINKLED1 Metabolic Control Based on Combined Phylogenetic and Biochemical Analyses

During triacylglycerol biosynthesis in developing oilseeds of Arabidopsis thaliana, fatty acid production is regulated by the seed-specific transcription factor WRINKLED1 (WRI1). WRI1 is known to directly stimulate the expression of fatty acid biosynthetic enzymes and a few targets in glycolysis. However, it remains unclear to what extent and how the conversion of sugars into fatty acid biosynthetic precursors in seeds is controlled by WRI1. Based on a previously reported DNA binding motif for WRI1, the ASML1/WRI1 (AW)- box, we developed a comparative genomics approach to search for conserved binding motifs in upstream regions of Arabidopsis thaliana protein-encoding genes and orthologous regions of 11 other Brassicaceae species. The AW-box was over-represented across orthologs for 915 Arabidopsis thaliana genes. Among these, 73 genes with functions in the biosynthesis of fatty acids and triacylglycerols and in glycolysis were enriched. For 90 AW-box sequences associated with these target genes, binding affinity to heterologously expressed Arabidopsis thaliana WRI1 protein was determined using Microscale Thermophoresis. Sites with low dissociation constants are preferentially located close to the transcriptional start site and are highly conserved between the 12 Brassicaceae species. Most of the associated genes were found to be co-expressed with WRI1 during seed development. When 46 automatically and manually curated genes containing conserved AW-sites with high binding affinity are mapped to central metabolism, a conserved regulatory blueprint emerges that infers concerted control of contiguous pathway sections in fatty acid biosynthesis and glycolysis. Among unexpectedly identified putative targets of WRI1 are plastidic fructokinase, phosphoglucose isomerase and several transcription factors. One sentence summaryA combined comparative genomics and in-vitro DNA binding assay approach was used to identify conserved binding sites for the WRINKLED1 transcription factor in central metabolism and lipid biosynthesis.

plant biology↗

bioRxiv2019

BIOTIN ATTACHMENT DOMAIN-CONTAINING proteins, inhibitors of ACCase, are regulated by WRINKLED1

WRINKLED1 (WRI1) is a transcriptional activator that binds to AW boxes in the promoters of many genes from central metabolism and FA synthesis, resulting in their transcription. BIOTIN ATTACHMENT DOMAIN-CONTAINING (BADC) proteins are homologs of BIOTIN CARBOXYL CARRIER PROTEIN (BCCP) that lack a biotin-attachment domain and are therefore inactive. In the presence of excess FA, BADC1 and BADC3 are primarily responsible for the observed long-term irreversible inhibition of ACETYL-COA CARBOXYLASE (ACCase), and consequently FA synthesis. Purified WRI1 bound with high affinity (Kds in the low nanomolar range) to canonical AW-boxes from the promoters of all three BADC genes. Consistent with this observation, the expression of BADC1, BADC2 and BADC3 genes and BADC1 protein levels were reduced in wri1-1 relative to wild type (WT), and BADCs gene expression and BADC1 protein levels also were elevated upon WRI1 overexpression. The double mutant badc1badc2 phenocopied wri1-1 with respect to both reduction in root length, and elevation of indole-3-acetic acid-Asp (IAA-Asp) levels relative to WT. Overexpression of BADC1 in wri1-1 decreased its IAA-Asp and partially rescued its short-root phenotype demonstrating a role for BADCs in seedling establishment. That WRI1 positively regulates genes encoding both FA synthesis and BADCs i.e., conditional inhibitors of FA synthesis, represents a coordinated mechanism to achieve lipid homeostasis in which plants couple the transcription their FA synthetic capacity with their capacity to biochemically downregulate it.\n\nOne sentence summaryWRI1 regulates genes encoding both fatty acid synthesis and inhibitors of FA synthesis (BADCs), creating a lipid homeostatic mechanism in which the transcription of FA synthetic capacity is coordinated with the capacity to biochemically downregulate FA synthesis.

plant biology↗