Dataset Information

Kinetic relaxation of giant vesicles validates diffusional softening in a binary lipid mixture.

ABSTRACT: The stiffness of biological membranes determines the work required by cellular machinery to form and dismantle vesicles and other lipidic shapes. Model membrane stiffness can be determined from the equilibrium distribution of giant unilamellar vesicle surface undulations observable by phase contrast microscopy. With two or more components, lateral fluctuations of composition will couple to surface undulations depending on the curvature sensitivity of the constituent lipids. The result is a broader distribution of undulations whose complete relaxation is partially determined by lipid diffusion. In this work, kinetic analysis of the undulations of giant unilamellar vesicles made of phosphatidylcholine-phosphatidylethanolamine mixtures validates the molecular mechanism by which the membrane is made 25% softer than a single-component one. The mechanism is relevant to biological membranes, which have diverse and curvature-sensitive lipids.

SUBMITTER: Sapp K

PROVIDER: S-EPMC10548837 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Kinetic relaxation of giant vesicles validates diffusional softening in a binary lipid mixture.

Sapp Kayla K Aleksanyan Mina M Kerr Kaitlyn K Dimova Rumiana R Sodt Alexander A

Physical review. E 20230501 5-1

The stiffness of biological membranes determines the work required by cellular machinery to form and dismantle vesicles and other lipidic shapes. Model membrane stiffness can be determined from the equilibrium distribution of giant unilamellar vesicle surface undulations observable by phase contrast microscopy. With two or more components, lateral fluctuations of composition will couple to surface undulations depending on the curvature sensitivity of the constituent lipids. The result is a broad ...[more]

PMID: 37329029

Similar Datasets

Project description:We developed a new (to our knowledge) protocol to generate giant unilamellar vesicles (GUVs) composed of mixtures of single lipopolysaccharide (LPS) species and Escherichia coli polar lipid extracts. Four different LPSs that differed in the size of the polar headgroup (i.e., LPS smooth > LPS-Ra > LPS-Rc > LPS-Rd) were selected to generate GUVs composed of different LPS/E. coli polar lipid mixtures. Our procedure consists of two main steps: 1), generation and purification of oligolamellar liposomes containing LPSs; and 2), electroformation of GUVs using the LPS-containing oligolamellar vesicles at physiological salt and pH conditions. Analysis of LPS incorporation into the membrane models (both oligolamellar vesicles and GUVs) shows that the final concentration of LPS is lower than that expected from the initial E. coli lipids/LPS mixture. In particular, our protocol allows incorporation of no more than 15 mol % for LPS-smooth and LPS-Ra, and up to 25 mol % for LPS-Rc and LPS-Rd (with respect to total lipids). We used the GUVs to evaluate the impact of different LPS species on the lateral structure of the host membrane (i.e., E. coli polar lipid extract). Rhodamine-DPPE-labeled GUVs show the presence of elongated micrometer-sized lipid domains for GUVs containing either LPS-Rc or LPS-Rd above 10 mol %. Laurdan GP images confirm this finding and show that this particular lateral scenario corresponds to the coexistence of fluid disordered and gel (LPS-enriched)-like micron-sized domains, in similarity to what is observed when LPS is replaced with lipid A. For LPSs containing the more bulky polar headgroup (i.e., LPS-smooth and LPS-Ra), an absence of micrometer-sized domains is observed for all LPS concentrations explored in the GUVs (up to ?15 mol %). However, fluorescence correlation spectroscopy (using fluorescently labeled LPS) and Laurdan GP experiments in these microscopically homogeneous membranes suggests the presence of LPS clusters with dimensions below our microscope's resolution (?380 nm radial). Our results indicate that LPSs can cluster into gel-like domains in these bacterial model membranes, and that the size of these domains depends on the chemical structure and concentration of the LPSs.

Dataset Information

Kinetic relaxation of giant vesicles validates diffusional softening in a binary lipid mixture.

Publications

Kinetic relaxation of giant vesicles validates diffusional softening in a binary lipid mixture.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets