Biology subjects

Lichocka, M.

Publications and source records attributed to Lichocka, M..

9 recordsLinked to original sources

bioRxiv2026

Annexin 5 is a key player in orchestrating the pollen sequestrome

Like dry seeds, mature pollen grains store a large reservoir of RNA species that enables rapid activation and germination under favorable conditions. The molecular mechanisms governing the accumulation of these RNA reservoirs remain poorly understood. Here, we show that the Arabidopsis pollen-specific protein annexin 5 (ANN5) localizes to the nucleolus and exerts dose-dependent control over ribosome biogenesis, as evidenced by altered steady-state rRNA levels in mature pollen. Ectopic expression of ANN5 also induced the accumulation of translationally repressed RNA in plant somatic tissues. Mechanistically, ANN5 interacts with histone deacetylase 2B (HD2B) and nucleolin (NUC1), which are known epigenetic modulators of ribosome biogenesis. In metabolically active cells, ANN5 associates with ribosomal and ribosome-associated proteins, suggesting it modulates the regulatory landscape of translation. We propose that the primary physiological role of ANN5 is to coordinate the formation and subsequent availability of RNA reserves during pollen maturation and activation.

cell biology↗

bioRxiv2025

Dynamic Rysto receptor remodeling controls its ability to confer extreme resistance

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) mediate effector-triggered immunity (ETI), often accompanied by a hypersensitive response (HR). Conversely, extreme resistance (ER) provides exceptionally rapid and effective antiviral protection without visible cell death, yet the molecular and physiological mechanisms underlying ER remain poorly defined. The TIR-NLR receptor Rysto recognizes the coat protein (CP) of potato virus Y (PVY) and can trigger either ER or HR depending on the context. Here, we demonstrate that the efficacy of Rysto-mediated ER relies on the orchestration of various defense mechanisms. These involve transcriptional priming, and spatial redistribution of the receptor and a subset of chaperones. Rysto-expressing lines exhibit a preactivated immune state, including increased expression of genes encoding glycine-rich proteins associated with the cell wall interface and thickness. Upon PVY infection, Rysto plants undergo rapid transcriptome reprogramming, including redox- and defense-related pathways. At the protein level, Rysto initially forms a pre-active complex with Hsp70 and CP-interacting cochaperonins (CPIPs) which is remodeled upon PVY CP binding. PVY CP competes for Hsp70, enabling Rysto to oligomerize into an active resistosome. This process is further accompanied by relocalization of a subpool of the receptor toward an interface of plasma membrane, cell wall. Our research reveals a chaperone-mediated activation mechanism and spatial immune repositioning that differentiate ER responses from traditional HR, offering a detailed system for achieving durable antiviral resistance in plants.

plant biology↗

bioRxiv2025

Structural basis for heat tolerance in plant NLR immune receptors.

Nucleotide-binding leucine-rich repeat (NLR) immune receptors sense pathogen molecules and oligomerize, initiating defense signaling. Some NLRs function poorly at elevated temperatures for unknown reasons. We show that temperature-sensitive NLRs retain ligand binding at elevated temperatures but are impaired in oligomerization. We identify key residues involved in temperature resilience. Structural modeling reveals stabilizing intramolecular interactions of the NB-ARC domain with surface residues of the adjacent leucine-rich repeat (LRR) that preserve receptor integrity and functionality under heat stress. These insights enable in silico classification of NLRs as temperature-sensitive or -tolerant and underpin design of temperature tolerant variants of temperature sensitive NLRs. These findings provide a mechanistic basis for temperature sensitivity in plant immune receptors and enable engineering of temperature-tolerant disease resistance in crops.

plant biology↗

bioRxiv2024

SpoIIDMP-driven peptidoglycan rearrangement is crucial for ribosome translocation into the spore.

In a spore-forming bacterium Bacillus subtilis transcription and translation are uncoupled and the translational machinery is located at the cell poles. During sporulation the cell undergoes morphological changes including asymmetric septation and chromosome translocation. However, the fate of translational machinery during sporulation has not been described. Here, using a combination of microscopic assays and mass spectrometry, we are tracking the ribosome localisation during sporulation in B. subtilis WT and mutants. We show that the ribosomes are associated with the asymmetric septum which is a functionally important organelle and that peptidoglycan rearrangement is essential for ribosome packing into the forespore. We also show that the feeding tube channel SpoIIIA-SpoIIQ is not required for the ribosome translocation, but is essential for maintaining the chromosome inside the spore. One-Sentence SummaryMovement of ribosomes into the spore of B. subtilis follows chromosome transport and is precisely orchestrated in the cell.

microbiology↗

bioRxiv2023

Translation in Bacillus subtilis is spatially and temporally coordinated during sporulation

Translational control during the intricate process of sporulation in Bacillus subtilis as a response to nutrient limitation is still underexplored. Here, we employed a comprehensive approach including RNA-seq, ribosome profiling and fluorescence microscopy to dissect the translational landscape of B. subtilis during sporulation. We identified two events of translation silencing and described the spatiotemporal changes in the subcellular location of translational machinery during sporulation. Using a triple knock-out strain (3KO) of zinc-independents paralogs of three zinc-dependent ribosomal proteins L31, L33 and S14, we investigated the potential regulatory role of ribosome during sporulation. The 3KO strain exhibited delayed sporulation, reduced germination efficiency, and dysregulated translation including expression of key metabolic and sporulation-related genes as well as disruptions in translation silencing, particularly in late sporulation.

microbiology↗

bioRxiv2021

The immune Rysto receptor recognizes a broadly conserved feature of potyviral coat proteins

Potyviruses are the largest group of plant RNA viruses, causing significant losses in many crops. Among them, potato virus Y (PVY) is particularly important, and enhances the severity of infections by other viruses. The Rysto gene confers PVY resistance and encodes a TIR-NLR intracellular immune receptors that recognizes PVY coat protein (CP). To define a minimal CP fragment sensed by Rysto, we created a series of truncated CP variants and expressed these CP derivatives in Rysto transgenic plants. Deletions that affect the 149 amino acid CP core region lose the ability to trigger Rysto-dependent defence activation. Furthermore, point mutations in the amino acid residues Ser126, Arg157, and Asp201 of the highly conserved RNA-binding pocket of potyviral CP, reduce or abolish Rysto-dependent responses, demonstrating that appropriate folding of the CP core is required for Rysto-mediated recognition. Consistent with these data, we found Rysto recognises CPs of various viruses that share a similar core region, but not those lacking it. Finally, we demonstrated that Rysto provides immunity to plum pox virus and turnip mosaic virus, demonstrating its wide range of applications in disease-resistant crop engineering. In parallel, we showed that CP triggered Rysto activation is SAG101- but not PAD4- or SA-level dependent. Our findings shed new light on how R proteins can detect viruses by sensing highly conserved structural patterns.

plant biology↗

bioRxiv2021

Arabidopsis annexin 5 controls plasma membrane properties in mature pollen grains

In Arabidopsis, a dry stigma surface enables a gradual hydration of pollen grains by a controlled release of water. Occasionally the grains may be exposed to extreme precipitations that cause rapid water influx, swelling and eventually lead to pollen membrane (PM) rupture. In metazoans, calcium- and phospholipids-binding proteins, referred to as annexins participate in repair of the plasma membrane damages. It remains unclear, however, how this process is conducted in plants. Here, we examined whether the plant annexin 5 (ANN5), the most abundant member of the annexin family in pollen, is involved in the restoration of PM integrity. We analyzed a cellular dynamics of ANN5 in the pollen grains undergoing in vitro and in vivo hydration. We observed a transient ANN5 association to PM during the in vitro hydration that did not occur in the pollen grains being hydrated on the stigma. To simulate a rainfall, we performed spraying of the pollinated stigma with deionized water that induced ANN5 accumulation at PM. Similarly, calcium or magnesium application affected PM properties and induced ANN5 recruitment to PM. Our data suggest a model, in which ANN5 is involved in the maintenance of membrane integrity in pollen grains exposed to osmotic or ionic imbalances.

plant biology↗

bioRxiv2019

Biochemical, Biophysical, and Functional Analyses of Two Isoforms of the SnRK2 Inhibitor AtSCS

SNF1-related protein kinases 2 (SnRK2s) are key signaling elements that regulate abscisic acid (ABA)-dependent plant development and responses to environmental stresses. Our previous data showed that the SnRK2-interacting Calcium Sensor (SCS) is an inhibitor of SnRK2 activity. In Arabidopsis thaliana, the use of alternative transcription start sites located within AtSCS gene results in two in-frame transcripts and subsequently two proteins, which differ only by the sequence position of the N-terminus. We described the longer AtSCS-A earlier, and now we describe the shorter AtSCS-B and compare both isoforms. The two forms differ significantly in their expression profiles in plant organs and in response to environmental stresses, in calcium binding properties, and conformational dynamics in the presence and absence of Ca2+. The results show that only AtSCS-A has the features of a calcium sensor. Both forms inhibit SnRK2 activity, but differ with respect to calcium dependence, as AtSCS-A requires calcium for inhibition, while AtSCS-B does not. Analysis of Arabidopsis plants stably expressing 35S::AtSCS-A-c-myc or 35S::AtSCS-B-c-myc in the scs-1 knockout mutant revealed that in planta both forms are negative regulators of the SnRK2 activity induced in response to ABA and regulate plant defense against water deficit. Moreover, the data present biochemical, biophysical, and functional properties of EF-hand-like motifs in plant proteins.\n\nOne sentence SummaryTwo isoforms of SnRK2-interacting calcium sensor are expressed in Arabidopsis; they differ in calcium binding properties, but both of them inhibit SnRK2s and subsequently fine tune ABA signaling.

plant biology↗

bioRxiv2018

Nucleus- and plastid-targeted annexin 5 promotes reproductive development in Arabidopsis and is essential for pollen and embryo formation

BackgroundPollen development is a strictly controlled post-meiotic process during which microspores differentiate into microgametophytes and profound structural and functional changes occur in organelles. Annexin 5 is a calcium- and lipid-binding protein that is highly expressed in pollen grains and regulates pollen development and physiology. To gain further insights into the role of ANN5 in Arabidopsis development, we performed detailed phenotypic characterization of Arabidopsis plants with modified ANN5 levels. In addition, interaction partners and subcellular localization of ANN5 were analyzed to investigate potential functions of ANN5 at cellular level.\n\nResultsHere, we report that RNAi-mediated suppression of ANN5 results in formation of smaller pollen grains, enhanced pollen lethality, and delayed pollen tube growth. ANN5 RNAi knockdown plants also displayed aberrant development during the transition from the vegetative to generative phase and during embryogenesis, reflected by delayed bolting time and reduced embryo size, respectively. At the subcellular level, ANN5 was delivered to the nucleus, nucleolus, and cytoplasm, and was frequently localized in plastid nucleoids, suggesting a likely role in interorganellar communication. Furthermore, ANN5-YFP co-immunoprecipitated with RABE1b, a putative GTPase, and interaction in planta was confirmed in plastidial nucleoids using FLIM-FRET analysis.\n\nConclusionsOur findings let us to propose that ANN5 influences basal cell homeostasis via modulation of plastid activity during pollen maturation. We hypothesize that the role of ANN5 is to orchestrate the plastidial and nuclear genome activities via protein-protein interactions however not only in maturing pollen but also during the transition from the vegetative to the generative growth and embryo development.

plant biology↗