Biology subjects

Roediger, A.

Publications and source records attributed to Roediger, A..

4 recordsLinked to original sources

bioRxiv2026

Tvp38/DedA Family Protein mediates biogenesis of chloroplast peripheral reticulum and envelope-to-thylakoid contacts in Arabidopsis

Chloroplasts of land plants are dynamic organelles essential for photosynthesis, metabolism, and plant adaptation to changing environmental conditions. Within chloroplasts, the inner envelope and thylakoid membranes are spatially separated but functionally interconnected. The inner envelope harbors enzymes involved in lipid synthesis for internal membranes and controls the exchange of metabolites and proteins, whereas the thylakoid membranes accommodate the machinery of the photosynthetic electron transport chain responsible for converting light energy into chemical energy. Therefore, efficient communication between these membrane systems is essential for maintaining chloroplast homeostasis and sustaining photosynthetic activity. In this study we have characterized the role of Tvp38/DedA Family Protein (TVPFP) in mediating inner envelope-to-thylakoid communication in Arabidopsis thaliana. Despite exhibiting wild-type-like growth and similar accumulation of the major thylakoid-anchored photosynthetic complexes, tvpfp mutants displayed reduced photosynthetic activity and increased abundance of photorespiration- and pigment-related proteins. Our results revealed that TVPFP localizes to the chloroplast envelope and undergoes post-translational modification when localized to the thylakoids. The unmodified form of TVPFP is enriched in high-molecular-weight complexes, suggesting that TVPFP oligomers are partially dissolved upon thylakoid relocation. Transmission electron microscopy data showed reduced abundance of vesicles as well as chloroplast peripheral reticulum (CPR) structures connecting the envelope and thylakoids in tvpfp mutants. Together, our results demonstrate that TVPFP fine-tunes photosynthesis by regulating vesicle abundance and biogenesis of CPR structures. Our findings shed light on the importance of envelope-to-thylakoid communication and the role of CPR structures in land plants.

plant biology↗

bioRxiv2026

Phenotypic characterization of an Arabidopsis stn7 stn8 pck2 triple mutant reveals only minor effects on chloroplast functions

Reversible protein phosphorylation is a key regulator of chloroplast function. Although chloroplast kinases STN7, STN8, and plastid casein kinase 2 (pCK2) regulate photosynthetic acclimation and other chloroplast processes, their functional interplay remains poorly understood. We generated and characterized the first Arabidopsis thaliana stn7 stn8 pck2 triple knockout mutant. Biochemical analyses confirmed the loss of all three kinase activities on established substrates. Growth resembled the pck2 single mutant, whereas photosynthetic fluorescence parameters reflected the stn7 stn8 double mutant. Thus, simultaneous disruption of all three kinases primarily combined the parental phenotypes, with little evidence of additive or synergistic effects under standard growth conditions. This triple mutant enables studies of chloroplast phosphorylation networks and demonstrates the remarkable resilience of chloroplast physiology to combined kinase loss.

plant biology↗

bioRxiv2024

RIG-I mediated neuron-specific IFN type 1 signaling in FUS-ALS induces neurodegeneration and offers new biomarker-driven individualized treatment options for (FUS-)ALS

Recent research has demonstrated significant aberrant activation of the innate immune system in ALS model systems due to mutations in SOD1, TARDBP and C9orf72 through stimulation of the TBK1-IRF3 pathway. This pathway can be activated, for example, by cGAS-STING-dependent sensing of cytosolic DNA that accumulates as a result of chronic DNA damage and defective mitochondria, both of which have been identified as early pathology in FUS-ALS spinal motor neurons (sMNs). Therefore, we analysed innate immune pathways in isogenic and non-isogenic FUSmut iPSC-derived sMNs, which revealed upregulation of interferon-stimulated genes (ISGs) and activation of the TBK1-IRF3 pathway in FUSmut sMNs. Notably, we found evidence for accumulation of cytosolic dsRNA and its sensor RIG-I in FUS-ALS. RIG-I, but not MDA5, was found to be significantly upregulated in FUSmut sMNs, and siRNA-mediated knockdown abolished the increased IFN1 activation in FUSmut sMNs. In post-mortem analysis, RIG-I was highly expressed in the remaining -MNs. IFN treatment of FUSwt sMNs phenocopied the axonal degeneration of FUSmut sMNs. Mechanistically, DNA damage induction did not increase ISG expression, but dsRNA was increased in the mitochondria of FUSmut sMNs. Mitochondrial transcription, a known source of dsRNA, was found to be upregulated in compartmental axonal RNAseq analysis and its inhibition reduced ISGs in FUS-ALS sMNs. Furthermore, the JAK-STAT inhibitor ruxolitinib alleviated the upregulated ISG expression and reversed the axonal degeneration of sMNs. Finally, we analysed ISG expression in peripheral blood samples from 18 FUS-ALS patients, eight of whom had a significantly elevated interferon signature. Blood ISGs correlated with disease progression rate and negatively with disease duration. RIG-I-mediated innate immune activation in sMNs may be an interesting novel individualised biomarker-driven therapeutic target in (FUS-) ALS. A one-sentence summary of your paperRIG-I-I-mediated innate immune activation is found in FUS-ALS spinal motor neurons caused by cytosolic dsRNA accumulation due to mitochondrial transcriptional activation and is amenable to JAK-STAT inhibition and might thus be an interesting novel individualized biomarker-driven therapeutic approach in (FUS-) ALS

neuroscience↗

bioRxiv2020

Chromoplast differentiation in bell pepper (Capsicum annuum) fruits

We report here a detailed analysis of the proteome adjustments that accompany chromoplast differentiation from chloroplasts during bell-pepper fruit ripening. While the two photosystems are disassembled and their constituents degraded, the cytochrome b6f complex, the ATPase complex as well as Calvin cycle enzymes are maintained at high levels up to fully mature chromoplasts. This is also true for ferredoxin (Fd) and Fd-dependent NADP reductase, suggesting that ferredoxin retains a central role in the chromoplasts redox metabolism. There is a significant increase in the amount of enzymes of the typical metabolism of heterotrophic plastids such as the oxidative pentose phosphate pathway (OPPP), amino acid and fatty acid biosynthesis. Enzymes of chlorophyll catabolism and carotenoid biosynthesis increase in abundance, supporting the pigment reorganization that goes together with chromoplast differentiation. The majority of plastid encoded proteins declines but constituents of the plastid ribosome and AccD increase in abundance. Furthermore, the amount of plastid terminal oxidase (PTOX) remains unchanged despite a significant increase in phytoene desaturase (PDS) levels, suggesting that the electrons from phytoene desaturation may be consumed by another oxidase. This may be a particularity of non-climacteric fruits such as bell pepper, that lack a respiratory burst at the onset of fruit ripening.

plant biology↗