Contrasting Effects of Cytoskeleton Disruption on Plasma Membrane Receptor Dynamics: Insights from Single-Molecule Analyses

Abstract

Traditional models such as the fluid mosaic model or the lipid raft hypothesis have shaped our understanding of plasma membrane (PM) organization. However, recent discoveries have extended these paradigms by pointing to the existence of micro- and nanodomains. Here, we investigated the role of the cytoskeleton in general and whether the picket fence model, established in animal cells, is transferable to the plant cell system. By using single-particle tracking photoactivated localization microscopy (sptPALM) in combination with genetically encoded enzymatic tools for the targeted disruption of the cytoskeleton, we studied the dynamics and nanoscale organization of a selection of PM receptor-like kinases (RLKs) and receptor-like proteins (RLPs). Our findings show that the disintegration of actin filaments leads to decreased diffusion, more restrictive motion patterns, and enlarged clusters, whereas the disintegration of microtubules results in increased diffusion, more unconstrained diffusive behavior, and decreased cluster sizes of the tested RLKs and RLPs. These results underscore the potential unique regulatory functions of cytoskeleton components in plants and suggest an altered mechanism compared to the picket fence model of the animal cell system. Our qualitative data can serve as the foundation for further investigations aimed at developing a comprehensive and refined model of protein dynamics and organization in plant cells.