Maryam Alqabandi1, Nicola de Franceschi1, Winfried Weissenhorn2, Patricia Bassereau1, Stéphanie Mangenot3, Sourav Maity4, Nolwenn Miguet2, Marta Bally5, Wouter H Roos4. 1. Laboratoire Physico Chimie Curie, Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, 75005, Paris, France. 2. Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000, Grenoble, France. 3. Laboratoire Physico Chimie Curie, Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, 75005, Paris, France. stephanie.mangenot@curie.fr. 4. Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands. 5. Umeå University, Department of Clinical Microbiology & Wallenberg Centre for Molecular Medicine, 90185, Umeå, Sweden.
Abstract
BACKGROUND: ESCRT-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast. In humans, ESCRT-III CHMP2 exists as two isoforms, CHMP2A and CHMP2B, but their physical characteristics have not been compared yet. RESULTS: Here, we use a combination of techniques on biomimetic systems and purified proteins to study their affinity and effects on membranes. We establish that CHMP2B binding is enhanced in the presence of PI(4,5)P2 lipids. In contrast, CHMP2A does not display lipid specificity and requires CHMP3 for binding significantly to membranes. On the micrometer scale and at moderate bulk concentrations, CHMP2B forms a reticular structure on membranes whereas CHMP2A (+CHMP3) binds homogeneously. Thus, CHMP2A and CHMP2B unexpectedly induce different mechanical effects to membranes: CHMP2B strongly rigidifies them while CHMP2A (+CHMP3) has no significant effect. CONCLUSIONS: We therefore conclude that CHMP2B and CHMP2A exhibit different mechanical properties and might thus contribute differently to the diverse ESCRT-III-catalyzed membrane remodeling processes.
BACKGROUND:ESCRT-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast. In humans, ESCRT-IIICHMP2 exists as two isoforms, CHMP2A and CHMP2B, but their physical characteristics have not been compared yet. RESULTS: Here, we use a combination of techniques on biomimetic systems and purified proteins to study their affinity and effects on membranes. We establish that CHMP2B binding is enhanced in the presence of PI(4,5)P2 lipids. In contrast, CHMP2A does not display lipid specificity and requires CHMP3 for binding significantly to membranes. On the micrometer scale and at moderate bulk concentrations, CHMP2B forms a reticular structure on membranes whereas CHMP2A (+CHMP3) binds homogeneously. Thus, CHMP2A and CHMP2B unexpectedly induce different mechanical effects to membranes: CHMP2B strongly rigidifies them while CHMP2A (+CHMP3) has no significant effect. CONCLUSIONS: We therefore conclude that CHMP2B and CHMP2A exhibit different mechanical properties and might thus contribute differently to the diverse ESCRT-III-catalyzed membrane remodeling processes.
Entities:
Keywords:
Atomic force microscopy (AFM); Bottom up approach; Endosomal sorting complexes Required for Transport (ESCRT); Giant unilamellar vesicles (GUV); Lipid-protein interactions; Mechanical properties; Membrane; Micropipette; Reconstituted system
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