Biology subjects

Kowalewska, L.

Publications and source records attributed to Kowalewska, L..

3 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↗

bioRxiv2024

Early seedling development in dark conditions is directly controlled by plastids through the GUN1-dependent plastid retrograde pathway

In dark growth conditions, seedlings develop specific features such as an elongated hypocotyl, a tightly folded apical hook, and non-green cotyledons. This dark-specific process, known as skotomorphogenesis, relies primarily on mitochondria and eventually etioplasts for energy. Our previous research shows that skotomorphogenesis is reprogrammed in response to mitochondrial and plastidial dysfunction. Even though the direct link between mitochondria and skotomorphogenesis was described, the impact of plastid dysfunction on early development could not be separated from mitochondrial stress. In this study, we aim to determine the direct connection between plastid functionality and skotomorphogenic response. In this situation, we analyze the phenotypic, molecular, and metabolic effects of treating etiolated seedlings using lincomycin and spectinomycin, which target plastid translation. Our results with the lincomycin treatment highlight the direct role of plastids in the control of early development, even in dark growth conditions, in the absence of any photosynthetic activity, and without the involvement of mitochondrial intermediates. Additionally, our findings suggest that GUN1 plays a regulatory role in regulating nuclear gene expression in response to plastid translation inhibition. Thanks to our study, we can now build a more precise model proposing a straight link between the reprogramming of early development and the dysfunction of plastids in dark-growth conditions. Significance statementIn underground germination conditions, seedlings follow a dark-specific development program, called skotomorphogenesis, that is required for their efficient emergence from the soil. Our study demonstrates that plastids play a crucial role in controlling skotomorphogenesis, even in the absence of photosynthetic activity and without affecting mitochondrial function, and therefore we propose that regulation of etioplast functions might contribute to the adaptation of seedling development to constraining environmental conditions.

plant biology↗

bioRxiv2024

Transmembrane domains of H1 and H3 hemagglutinin contribute to membrane fusion in a different manner

Hemagglutinin (HA), a fusion protein of influenza virus, has been extensively researched as a model fusion viral protein. However, most of the efforts focus on the fusion peptide (FP) and the ectodomain, while relatively little is known about the "membrane anchor", a transmembrane domain (TMD). While the structural insights on H1 subtype full-length HA underlay the influence of TMD on the ectodomain orientations, the structures representing the other phylogenetic group are still unavailable. Inspired by the sequential varieties of TMDs in both groups, we performed a series of experiments on full-length HA proteins with H1and H3-swapped TMD domains in virus-like particles (VLP). In parallel, we studied the behaviour an and interplay of FP and TMD-corresponding fragments with the use of artificial membrane systems and molecular dynamics simulations. We detect clearly a distinct interplay between FP and TMDs in the two phylogenetic groups. We observe that TMD-dependent fusion activity originates from TMD-lipid interactions, but not direct FP:TMD complexing.

biophysics↗