Biology subjects

Gombos, S.

Publications and source records attributed to Gombos, S..

3 recordsLinked to original sources

bioRxiv2025

In situ architecture of plasmodesmata suggests mechanisms controlling intercellular exchange

Plasmodesmata are nanoscopic channels that traverse plant cell walls, establishing membrane and cytoplasmic continuity between adjacent cells to enable direct intercellular exchange. Although numerous components have been identified, their molecular organization and roles in controlling passage remain unclear. Here, we used cryo-electron tomography to resolve the in situ architecture of plasmodesmata in Physcomitrium patens across tissues and physiological states. We show how callose deposition at the cell wall shapes channel architecture to modulate permeability and identify helical protein assemblies formed by Multiple C2 domain and Transmembrane Proteins (MCTPs), which scaffold a central endoplasmic reticulum tubule and tether it to the plasma membrane. These findings define core architectural features of plasmodesmata and establish a structural framework for understanding how membrane, protein and cell wall components coordinate intercellular connectivity in plants.

cell biology↗

bioRxiv2024

Identification of nuclear pore proteins at plasmodesmata

Plasmodesmata (PD) mediate intercellular exchange of small molecules, RNAs and proteins between plant cells with an apparent exclusion limit for passive non-specific transport, and transport of specific cargo mediated by mediators. PD and nuclear pore complexes (NPC) are nanometer sized micropores with strikingly similar properties. Cargo translocation through NPC is mediated by phase separating FG-nucleoporins (FG-NUP). Here, bioinformatics, proteomics and fluorescence imaging identified FG-NUPs at PD. Transient expression of GFP fusions at low and intermediate expression levels supported dual localization of 12 NUPs to NPC and PD. Structured illumination microscopy detected the transmembrane anchor NUP CPR5 close to orifices of PD. cpr5 mutants showed reduced intercellular short-root (SHR) transport. However, transport defects cannot be excluded due to indirect effects in the mutants. Identification of FG-NUPs at PD is consistent with the recruitment of NUPs to form a PD pore gating complex consistent with phase separation domains as diffusion barriers at PD. Further analyses will be required to determine whether NUPs are bona fide PD components, or accumulate at PD in certain conditions, or may serve intermediate NPC storage.

cell biology↗

bioRxiv2022

A high confidence Physcomitrium patens plasmodesmata proteome by iterative scoring and validation reveals diversification of cell wall proteins during evolution

Cells of multicellular organisms exchange nutrients, building blocks and information. In animals, this happens via gap junctions, in plants via plasmodesmata (PD). PD have striking properties, translocating a large range of molecules from ions, to metabolites, RNA and proteins up to 40 kDa. PD are hard to characterize due to being deeply embedded into cell walls and the presence of several membranes. While previous studies of protein composition of PD from angiosperms identified large lists of proteins, few were validated. Here, we developed a PD scoring approach in conjunction with systematic localization on a large scale to define a high-confidence PD proteome of Physcomitrium patens. This high confidence PD proteome comprises nearly 300 proteins, which together with the bona fide PD proteins from literature, are made available in the public PDDB database. Conservation of localization across plant species strengthens the reliability of plant PD proteomes and provides a basis for exploring the evolution of this important organelle. In particular, the P. patens PD proteome was highly enriched in cell wall modifying proteins. Callose-degrading glycolyl hydrolase family 17 (GHL17) proteins are presented as an abundant PD protein family with representatives across an evolutionary scale. Exclusively members of the alpha-clade of the GHL17 family are shown to be PD localized and their orthologs occur only in plant species which have developed PD. Members of the EXORDIUM-family and xyloglucan transglycosylases are additional cell-wall located proteins highly abundant in the P. patens PD proteome also showing evolutionary diversification of PD localized family members from other clade members.

plant biology↗