Abstract
BackgroundESCRT-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.ResultsHere, 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.ConclusionsWe therefore conclude that CHMP2B and CHMP2A exhibit different mechanical properties and might thus contribute differently to the diverse ESCRT-III-catalyzed membrane remodeling processes.
Highlights
Endosomal sorting complexes Required for Transport (ESCRT)-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast
The endosomal sorting complex required for transport (ESCRT-III) complex is involved in a variety of cellular processes [1] such as biogenesis of multivesicular bodies (MVB) [2], plasma membrane wound repair [3], neuron pruning [4], dendritic spine formation [5], nuclear envelope repair or nuclear envelope sealing during
We establish that CHMP2B binding is enhanced in the presence of PI(4,5)P2 lipids forming a protein network on the membrane surface, whereas CHMP2A+CHMP3 interact homogenously with membranes via electrostatic interactions without phosphoinositide binding specificity
Summary
ESCRT-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast. The endosomal sorting complex required for transport (ESCRT-III) complex is involved in a variety of cellular processes [1] such as biogenesis of multivesicular bodies (MVB) [2], plasma membrane wound repair [3], neuron pruning [4], dendritic spine formation [5], nuclear envelope repair or nuclear envelope sealing during. The sequence of recruitment of ESCRT-III proteins during MVB formation is Vps20-Snf7-Vps24Vps, forming a core complex [12]. Their human homologs are respectively CHMP6-CHMP4 (A, B, C)-CHMP3CHMP2 (A, B). The dual roles of CHMP2A and CHMP2B in the interaction and remodeling of membranes remain unclear [6, 13,14,15,16,17] (Additional file 1: Figure S1-C)
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