Simultaneous adjustments of major mitochondrial pathways through redox regulation of dihydrolipoamide dehydrogenase (mtLPD1)

Timm, S.; Klaas, N.; Niemann, J.; Jahnke, K.; Alseekh, S.; Zhang, Y.; Souza, P.; Hou, L.-Y.; Geigenberger, P.; Daloso, D. M.; Fernie, A. R.; Hagemann, M.

doi:10.1101/2022.04.02.486831

bioRxiv · 10.1101/2022.04.02.486831

Simultaneous adjustments of major mitochondrial pathways through redox regulation of dihydrolipoamide dehydrogenase (mtLPD1)

Timm, S.·Klaas, N.·Niemann, J.·Jahnke, K.·Alseekh, S.·Zhang, Y.·Souza, P.·Hou, L.-Y.·Geigenberger, P.·Daloso, D. M.·Fernie, A. R.·Hagemann, M.

View original source ↗Export metadata ↓

Abstract

Thioredoxins (TRX) are pivotal for the redox regulation of enzyme activities to adjust metabolic fluxes towards environmental changes. Previous reports demonstrated TRX o1 and h2 impact on mitochondrial metabolism including photorespiration and the tricarboxylic acid (TCA) cycle. Here, we aimed to unravel potential specificities between regulation modes of both TRXs, especially under conditions with short-term changes in photorespiration. Therefore, short-term metabolite responses of single TRX mutants were analyzed after exposure to altered CO2/O2 ratios during darkness and illumination. This approach was complemented by comprehensive characterization of multiple Arabidopsis mutants lacking either one or both TRX in the wild-type Arabidopsis or the glycine decarboxylase (GDC) T-protein knock down line (gldt1). The results provided evidence for additive effects of combined TRX o1 and h2 deficiency to suppress growth, photosynthesis and mitochondrial metabolism. Quantification of pyrimidine nucleotides in conjunction with metabolite and 13C-labelling approaches revealed a rather uniform impact on mitochondrial dihydrolipoamide dehydrogenase (mtLPD1) dependent pathways. Biochemical analysis of recombinant mtLPD1 demonstrated its inhibition by NADH, pointing at an additional measure to fine-tune its in vivo activity. Collectively, we propose that TRX o1 and h2 contribute to the communication of altered subcellular redox-states through direct and indirect regulation of mtLPD1. This regulation module might represent a common intercept for simultaneous adjustments in the operation of photorespiration, the TCA-cycle and the degradation of branched chain amino acids. One-sentence summaryRedox regulation of mitochondrial dihydrolipoamide dehydrogenase (mtLPD1) simultaneously modulates photorespiration, the tricarboxylic acid (TCA)-cycle and branched chain amino acid (BCAA) degradation in response to rapid environmental changes.

Explore related subjects

plant biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Timm, S., Klaas, N., Niemann, J., Jahnke, K., Alseekh, S., Zhang, Y., Souza, P., Hou, L.-Y., Geigenberger, P., Daloso, D. M., Fernie, A. R., Hagemann, M.. 2022-04-03. Simultaneous adjustments of major mitochondrial pathways through redox regulation of dihydrolipoamide dehydrogenase (mtLPD1). https://doi.org/10.1101/2022.04.02.486831

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Growth, yield, and quality of hot pepper (Capsicum annuum L.) as affected by the combined application of liquid bio-slurry and NPS fertilizer rates in Kucha, Gamo zone, south Ethiopia

Hot pepper (Capsicum annuum L.) is a key cash and nutritional crop in Ethiopia, yet its productivity remains constrained by inadequate and imbalanced soil nutrient management. Therefore, the field experiment was conducted in Kucha woreda, Gamo Zone, South Ethiopia, during the 2024/25 cropping season to investigate the effect of liquid bio-slurry and NPS fertilizer rates on growth, yield and quality of hot pepper. The experiment consisted of 16 treatments arranged in a factorial combination of four liquid bio-slurry (LBS) rates (0, 20, 40, and 60 m3 ha-1) and four NPS fertilizer rates (0, 75, 150, and 225 kg ha-1) using a randomized complete block design with three replications. All experimental data were collected following standard agronomic procedures and subjected to analysis of variance using GenStat statistical software (18th edition). The results revealed that both the main and interaction effects of liquid bio-slurry and NPS significantly (p < 0.01) influenced phenological, growth, yield, and quality parameters. The combined application of 150 kg ha-1 NPS and 60 m3 ha-1 LBS produced the highest marketable dry fruit yield (2.94 t ha-1) and total dry fruit yield (3.16 t ha-1), representing a 129.69% yield advantage over the control (1.28 t ha-1) in the case of marketable dry fruit yield. The findings demonstrate that integrated nutrient management using combined LBS and NPS fertilizers significantly enhanced the productivity and quality of hot pepper. Therefore, the application of 150 kg ha-1 NPS combined with 60 m3 ha-1 liquid bio-slurry is recommended for improved hot pepper production for the study area and similar agro-ecological conditions.

plant biology↗

bioRxiv2026

Robust planar morphogenesis in leaf-like organs requires callose-dependent coordination of division and growth

Planar organs, such as leaves, are key developmental innovations underlying the evolutionary success of plants. In vascular plants, building a planar organ requires coordinating cell division and growth both within the organ plane and across multiple, mechanically distinct cell layers. Phyllids, the leaf-like organs of bryophytes, typically consist of a single cell layer and offer a minimal system to decouple in-plane growth coordination from inter-layer mechanics. Here, we investigate how robust planar morphogenesis is achieved in phyllids, using the moss Physcomitrium patens as a bryophyte model. We show that impaired cytokinesis, caused by the loss of a callose synthase gene, disrupts growth gradients, ultimately yielding smaller, non-planar organs of variable shape. Combining quantitative live imaging with computational modeling, we show that the severity of shape defects in mutants depends on the spatial distribution and developmental timing of local growth arrests. These findings reveal how callose-dependent coordination between cell division and in-plane growth prevents mechanical conflicts and maintains planarity in a monolayered plant organ.

plant biology↗

bioRxiv2026

Structural determinants underlie the essentiality of the m-type thioredoxin TrxA in Synechocystis

Thioredoxins are central regulators of thiol-based redox signaling in photosynthetic organisms, where multiple isoforms with partially overlapping functions coexist. Among them, TrxA is the cyanobacterial homolog of chloroplast m-type thioredoxins and the only thioredoxin known to be essential in cyanobacteria. However, it is unclear whether this essentiality is due to its high intracellular abundance or to its specific molecular properties. Here, we evaluated the ability of different thioredoxins to functionally replace TrxA and used TrxA/TrxB chimeras to identify the structural determinants underlying its functional specificity. Overexpression of TrxB, TrxQ or TrxC did not support complete segregation of a disrupted trxA locus, although the proteins accumulated to levels comparable to those of endogenous TrxA. Similarly, heterologous expression of NTRC did not rescue the phenotype associated with reduced TrxA levels. Comparative structural analysis revealed differences in surface electrostatics and structural features surrounding the catalytic site of TrxA compared with the other thioredoxins. Analysis of TrxB/TrxA chimeras showed that determinants required for functional complementation are primarily located within the C-terminal region of TrxA. Chimeric variants also differed in their ability to activate cyanobacterial FBP/SBPase and pea chloroplast FBPase in vitro, supporting a role for this region in target-specific interactions. Together, these results demonstrate that the essential function of TrxA cannot be explained by protein abundance alone and requires molecular determinants located primarily within its C-terminal region.

plant biology↗