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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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The Synthesis and Biological Evaluation of Indolactam Alkaloids
In this work, we execute a general synthetic strategy to access novel indolactam alkaloids, which are agonists of protein kinase C. This protocol allowed for the most efficient reported syntheses of indolactam V (ILV) stereoisomers, while also affording the large-scale production of natural product (–)-ILV. Structure–activity studies were conducted with these compounds to elucidate the elements necessary to promote PKC-mediated cellular response. EC50 measurements in leukemia and lymphoma cell lines, as well as molecular docking analyses with the PKCδ C1B domain, provided the foundation for these studies. A distinct correlation between in vitro activity and the conformation of the macrocyclic lactam ring was discovered, which can guide design efforts for therapeutics that target the PKC regulatory domain.
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- Award ID(s):
- 1726903
- PAR ID:
- 10178070
- Date Published:
- Journal Name:
- Synthesis
- Volume:
- 51
- Issue:
- 23
- ISSN:
- 0039-7881
- Page Range / eLocation ID:
- 4443 to 4451
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1055/s-0039-1690198
