Biology subjects

Parys, K.

Publications and source records attributed to Parys, K..

5 recordsLinked to original sources

bioRxiv2026

Evolutionary diversification of the SymRK receptor family in land plants

Plant receptor-like kinases (RLKs) are involved in diverse processes, ranging from growth and reproduction to interactions with microbes. Variation in the extracellular domains delineates several RLKs subfamilies, including the malectin-like domain leucine-rich repeat receptor-like kinases (MLD-LRR-RLKs). Symbiosis Receptor-like Kinase (SymRK) is the prototypical member of MLD-LRR-RLKs and is required for microbial accommodation in host roots during root endosymbiosis. Yet, comparative phylogenetic analysis of SymRK orthologs in the broader context of MLD-LRR-RLK subfamily evolution remains limited. In this study, we examined the inventory, phylogeny and clade-specific evolutionary and transcriptional characteristics of this receptor group. SymRK and its closest homologs are present in most land plant lineages and group into four major clades and six additional species-specific clades. These clades can be distinguished by their evolutionary characteristics as either conserved with reduced gene copy number changes (including SymRK) or expanded and diversified, as observed in clade IV. Clade IV dynamics are largely driven by tandem gene duplications, which often arise within gene clusters. We further analysed the evolutionary characteristics of MLD-LRR-RLKs at the population level in Arabidopsis thaliana accessions. We found that some genes are conserved across accessions and are therefore likely to be functionally important, whereas a subset of genes, often located within tandem clusters, are highly diverse and likely contribute to accession-specific adaptations. Finally, most MLD-LRR-RLKs in the A. thaliana Col-0 accession are expressed in roots and respond broadly to biotic stimuli at the transcriptional level. Notably, clustered genes frequently exhibited divergent expression profiles, suggesting transcriptional diversification. Together, we revealed two contrasting evolutionary characteristics among members of the MLD-LRR-RLK subfamily, potentially associated with their functions in plants.

plant biology↗

bioRxiv2026

Sequence adaptations in the intracellular domain of Symbiosis receptor-like kinase (SymRK) promoted infection thread progression in root nodule primordia

The uptake of nitrogen-fixing bacteria into living plant cells and the intracellular accommodation of arbuscular mycorrhiza (AM) fungi requires the plasma membrane-localised Symbiosis Receptor-like Kinase (SymRK). AM is widespread across terrestrial vascular plant lineages, while the nitrogen-fixing root nodule symbiosis (RNS) is restricted to one clade within the eurosids. This distribution led to the concept that SymRK was adopted during evolution to mediate RNS. Comparative analyses revealed that SymRK orthologs from the eurosid clade support RNS while SymRK from the phylogenetically distant species Solanum lycopersicum (tomato) does not. To dissect the molecular basis for this different functionality, we carried out complementation analyses of the Lotus japonicus symrk-3 mutant which is unable to form AM or RNS. Domains swap chimera from the tomato and L. japonicus SymRK orthologs revealed that the intracellular domain of L. japonicus SymRK is necessary and for cortical infection thread (IT) and symbiosome development at 21 days post inoculation. Notably, this signalling specificity could be overcome by ectopic expression of tomato SymRK, pointing to altered protein dosage as a potential determinant of function. Consistent with this idea, SINA family E3 ubiquitin ligases interacted with and ubiquitinylated L. japonicus SymRK, but not tomato SymRK. In yeast two hybrid analysis, the interaction of SymRK with SINA2 and SINA4 depended on the C-terminal intrinsically disordered tail region of L. japonicus SymRK. We conclude that the SymRK intracellular domain evolved interaction capabilities with SINA E3 ligases which correlates with its ability to support RNS.

plant biology↗

bioRxiv2026

The 2D and 3D ultrastructure of symbiosomes and associated vesicular structures in Lotus japonicus root nodule symbiosis

In root nodule symbiosis, symbiosome compartments accommodate nitrogen-fixing rhizobia inside the plant cell. Differentiated into bacteroids, the rhizobia are surrounded by a peribacteroid space and a plant-derived peribacteroid membrane, which separates them from the plant cytoplasm but allows signal and nutrient exchange between host and microbe. The morphological features of symbiosomes are primarily determined by ultrastructural single focal plane imaging, with limited information about spatial details. This study combines 2D and 3D imaging, using transmission electron microscopy and focused ion beam scanning electron microscopy as complementary techniques to analyse the symbiosome ultrastructure and organisation in Lotus japonicus wild-type plants. The 3D model of a mature colonised root nodule cell region demonstrates a dense, puzzle-like arrangement of symbiosomes relative to one another and adjacent plant organelles. The symbiosome shape and size depends on the orientation and number of bacteroids within the compartment and features connective tubular structures. Furthermore, vesicular structures, some likely of bacterial origin, were present at the interface. The study presents a multi-angled analysis of symbiosome-related structures, highlighting their volumes, spatial distribution, and pronounced compactness. Interface associated vesicles, protrusions and connective structures hint towards a dynamic and flexible system that contributes to the plant-microbe crosstalk.

plant biology↗

bioRxiv2022

Silent recognition of flagellins from human gut commensal bacteria by Toll-like receptor 5

Flagellin, the protein unit of the bacterial flagellum, stimulates the innate immune receptor Toll-like receptor (TLR)5 following pattern recognition, or evades TLR5 through lack of recognition. This binary response fails to explain the weak agonism of flagellins from commensal bacteria, raising the question of how TLR5 response is tuned. Here, we describe a novel class of flagellin-TLR5 interaction, termed silent recognition. Silent flagellins are weak agonists despite high affinity binding to TLR5. This dynamic response is tuned by TLR5-flagellin interaction distal to the site of pattern recognition. Silent flagellins are produced primarily by the abundant gut bacteria Lachnospiraceae and are enriched in non-Western populations. These findings provide a mechanism for the innate immune system to tolerate commensal-derived flagellins. One-Sentence SummaryTLR5 sensitively recognizes, but responds weakly to, flagellins from gut commensal bacteria.

microbiology↗

bioRxiv2018

Sulfated RaxX, which represents an unclassified group of ribosomally synthesized post-translationally modified peptides, binds a host immune receptor

The rice immune receptor XA21 is activated by the sulfated microbial peptide RaxX (required for activation of XA21-mediated immunity X) produced by Xanthomonas oryzae pv. oryzae (Xoo). Mutational studies and targeted proteomics revealed that RaxX is processed and secreted by the protease/transporter RaxB, whose function can be partially fulfilled by a noncognate peptidase-containing transporter B (PctB). RaxX is cleaved at a Gly-Gly motif, yielding a mature peptide that retains the necessary elements for RaxX function as an immunogen and host peptide hormone mimic. These results indicate that RaxX is a founding member of a previously unclassified and understudied group of tyrosine sulfated RiPPs (ribosomally synthesized, post-translationally modified peptides). We further demonstrate that sulfated RaxX directly binds XA21 with high affinity. This work reveals a complete, previously uncharacterized biological process: bacterial RiPP biosynthesis, secretion, binding to a eukaryotic receptor and triggering of a robust host immune response.

microbiology↗