Membrane nanotubes transform into double- membrane sheets at condensate droplets

• 成果类型: Article
• 署名作者: Zhao, Ziliang; Satarifard, Vahid; Lipowsky, Reinhard; Dimova, Rumiana
• 署名单位: Max Planck Society; Leibniz Institut fur Photonische Technologien; Friedrich Schiller University of Jena; Yale University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8852
• DOI: 10.1073/pnas.2321579121
• 发表日期: 2024-06-25
• 关键词: 2-phase polymer-solutions; encapsulation; proteins; mechanisms; oxidation; insights; dextran

摘要

Cellular membranes exhibit a multitude of highly curved morphologies such as buds, nanotubes, cisterna - like sheets defining the outlines of organelles. Here, we mimic cell compartmentation using an aqueous two - phase system of dextran and poly(ethylene glycol) encapsulated in giant vesicles. Upon osmotic deflation, the vesicle membrane forms nanotubes, which undergo surprising morphological transformations at the liquid-liquid interfaces inside the vesicles. At these interfaces, the nanotubes transform into cisterna - like double - membrane sheets (DMS) connected to the mother vesicle via short membrane necks. Using super - resolution (stimulated emission depletion) microscopy and theoretical considerations, we construct a morphology diagram predicting the tube - to - sheet transformation, which is driven by a decrease in the free energy. Nanotube knots can prohibit the tube - to - sheet transformation by blocking water influx into the tubes. Because both nanotubes and DMSs are frequently formed by cellular membranes, understanding the formation and transformation between these membrane morphologies provides insight into the origin and evolution of cellular organelles.