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Azadbakht, A. (2024)

Interactions from lipid membrane deformations

Doctoral Thesis
Biological cells, the basic building blocks of all life forms, are surrounded by a lipid membrane. More than half of the membrane is occupied by membrane proteins, which can regulate the cell functionality through specific arrangements. To regulate the arrangements several proteins have to work together. In addition to direct forces, there exists an indirect force between the proteins, which stems from their deformation of the membrane and contributes to their self-organization. Since the actual membrane is very crowded and proteins are too tiny and complex to measure this interaction, in this thesis we used a model system consisting of lipid membranes and solid particles to study the deformation-mediated interaction. We experimentally confirmed for the first time that, unlike many known forces, this deformation-mediated interaction is not additive, i.e. the strength and range of three (or more) deformations cannot be obtained by simple addition of the interactions between pairs...Show moreBiological cells, the basic building blocks of all life forms, are surrounded by a lipid membrane. More than half of the membrane is occupied by membrane proteins, which can regulate the cell functionality through specific arrangements. To regulate the arrangements several proteins have to work together. In addition to direct forces, there exists an indirect force between the proteins, which stems from their deformation of the membrane and contributes to their self-organization. Since the actual membrane is very crowded and proteins are too tiny and complex to measure this interaction, in this thesis we used a model system consisting of lipid membranes and solid particles to study the deformation-mediated interaction. We experimentally confirmed for the first time that, unlike many known forces, this deformation-mediated interaction is not additive, i.e. the strength and range of three (or more) deformations cannot be obtained by simple addition of the interactions between pairs of deformations. We found that the interaction weakens with increasing number of membrane-deforming particles and that the particle become less ordered. We investigated deformations in both directions of the membrane and found that the interaction can be both repulsive and attractive, and furthermore depends on the shape of the deformation. This thesis helps to better understand the organization of proteins that deform cellular membranes.
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Membrane-deformation
Curvature-mediated interaction
Self-assembly
Many-body interaction effects
Colloidal Spheres
Colloids
Lipid membranes
Ligand-receptor interactions
Endocytosis
Engulfment
All authors
Azadbakht, A.
Supervisor
Kraft, D.J.
Co-supervisor
Morin, A.
Committee
Dufresne, E.R.; Saric, A.; Aarts, J.; Jawerth, L.; Noort, J. van; Schmidt, T.
Qualification
Doctor (dr.)
Awarding Institution
Leiden Institute of Physics (LION), Faculty of Science, Leiden University
Date
2024-01-11
Title of host publication
Casimir PhD Series
ISBN (print)
9789085935858

Publication Series

Name
2023-39

Funding

Sponsorship
The work described in this thesis was financed by the physics department at Leiden University