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Endocytosis and endosomal trafficking of plasma membrane proteins for degradation regulate cellular homeostasis and development. As part of these processes, ubiquitinated plasma membrane proteins (cargo) are recognized, clustered, and sorted into intralumenal vesicles of multivesicular endosomes by ESCRT (Endosomal Sorting Complexes Required for Transport) proteins. At endosomes, ESCRT proteins recognize ubiquitinated cargo and mediate the deformation of the endosomal membrane in a negative geometry, away from the cytosol. ESCRTs are organized in five major complexes that are sequentially recruited to the endosomal membrane where they mediate its vesiculation and cargo sequestration. ESCRTs also participate in other membrane remodeling events and are widely conserved across organisms, both eukaryotes and prokaryotes. Plants contain both conserved and unique ESCRT components and show a general trend toward gene family expansion. Plant endosomes show a wide range of membrane budding patterns with potential implications in cargo sequestration efficiency, plant development, and hormone signaling. Understanding the diversification and specialization of plant ESCRT proteins can provide valuable insights in the mechanisms of ESCRT-mediated membrane bending. In this review, we discuss the endosomal function of ESCRT proteins, their unique features in plants, and the potential connections to the modes of plant endosomal vesiculation.
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This content will become publicly available on October 29, 2025
Endosomal membrane budding patterns in plants
Multivesicular endosomes (MVEs) sequester membrane proteins destined for degradation within intralumenal vesicles (ILVs), a process mediated by the membrane-remodeling action of Endosomal Sorting Complex Required for Transport (ESCRT) proteins. InArabidopsis, endosomal membrane constriction and scission are uncoupled, resulting in the formation of extensive concatenated ILV networks and enhancing cargo sequestration efficiency. Here, we used a combination of electron tomography, computer simulations, and mathematical modeling to address the questions of when concatenated ILV networks evolved in plants and what drives their formation. Through morphometric analyses of tomographic reconstructions of endosomes across yeast, algae, and various land plants, we have found that ILV concatenation is widespread within plant species, but only prevalent in seed plants, especially in flowering plants. Multiple budding sites that require the formation of pores in the limiting membrane were only identified in hornworts and seed plants, suggesting that this mechanism has evolved independently in both plant lineages. To identify the conditions under which these multiple budding sites can arise, we used particle-based molecular dynamics simulations and found that changes in ESCRT filament properties, such as filament curvature and membrane binding energy, can generate the membrane shapes observed in multiple budding sites. To understand the relationship between membrane budding activity and ILV network topology, we performed computational simulations and identified a set of membrane remodeling parameters that can recapitulate our tomographic datasets.
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- Award ID(s):
- 2114603
- PAR ID:
- 10583418
- Publisher / Repository:
- National Academy of Science USA
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 121
- Issue:
- 44
- ISSN:
- 0027-8424
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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