Plant Sterol Clustering Correlates with Membrane Microdomains as Revealed by Optical and Computational Microscopy

Abstract

Local inhomogeneities in lipid composition play a crucial role in the regulation of signal transduction and membrane traffic. This is particularly the case for plant plasma membrane, which is enriched in specific lipids, such as free and conjugated forms of phytosterols and typical phytosphingolipids. Nevertheless, most evidence for microdomains in cells remains indirect, and the nature of membrane inhomogeneities has been difficult to characterize. We used a new push–pull pyrene probe and fluorescence lifetime imaging microscopy (FLIM) combined with all-atom multiscale molecular dynamics simulations to provide a detailed view on the interaction between phospholipids and phytosterol and the effect of modulating cellular phytosterols on membrane-associated microdomains and phase separation formation. Our understanding of the organization principles of biomembranes is limited mainly by the challenge to measure distributions and interactions of lipids and proteins within the complex environment of living cells. Comparing phospholipids/phytosterol compositions typical of liquid-disordered (Ld) and liquid-ordered (Lo) domains, we furthermore show that phytosterols play crucial roles in membrane homeostasis. The simulation work highlights how state-of-the-art modeling alleviates some of the prior concerns and how unrefuted discoveries can be made through a computational microscope. Altogether, our results support the role of phytosterols in the lateral structuring of the PM of plant cells and suggest that they are key compounds for the formation of plant PM microdomains and the lipid-ordered phase.

Arabidopsis HSFA9 Acts as a Regulator of Heat Response Gene Expression and the Acquisition of Thermotolerance and Seed Longevity

“…2019 ). This technique allowed us to examine the conformational dynamics and functional characteristics of protein at an atomic level of detail ( Tang et al. 2021 ).…”

An Overview of Cryo-Scanning Electron Microscopy Techniques for Plant Imaging

“…This has been applied to, for example, anthocyanic vacuolar inclusions [60] and oil droplets [61] within the cell. At the cell surface (the plasma membrane), fluorescence microscopy techniques have been invaluable for studying membrane microdomains [62,63], but the contribution of low-temperature SEM imaging has not been explored. Beyond the plasma membrane, CryoSEM imaging alongside fluorescence imag-ing with glycan-targeted probes suggest that phase separation of some cell wall constituents does occur [48,64,65].…”

Special Issue “Biomembranes and Biomimetic Membranes—From Model Analysis to ‘In Vivo’ Study”

“…Plant cell membranes have been studied by Tang et al [1]. They wanted to improve their understanding of the nature of phytosterol-phospholipid interaction and find out how the phytosterols modulate the mechanical properties of lipid membranes.…”