Related Experiment Video
Updated: Dec 26, 2025
07:49
Spontaneous Formation and Rearrangement of Artificial Lipid Nanotube Networks as a Bottom-Up Model for Endoplasmic Reticulum
Published on: January 22, 2019
8.2K
Formation of pre-pore complexes of pneumolysin is accompanied by a decrease in short-range order of lipid molecules
Bayan H A Faraj1, Liam Collard2,3, Rachel Cliffe2
1Department of Respiratory Sciences, University of Leicester, Leicester, LE1 9HN, United Kingdom.
Scientific Reports
|March 14, 2020
Summary
Pneumolysin oligomers form membrane channels by altering lipid packing. Pre-pore complex assembly significantly changes lipid order, transforming the bilayer into a fluid-disordered phase with cholesterol-rich domains.
Area of Science:
- Biophysics
- Membrane Biology
- Protein-Lipid Interactions
Background:
- Pneumolysin forms pores in cell membranes.
- Pore formation involves protein oligomerization and membrane insertion.
- The role of lipid dynamics in pore formation is not fully understood.
Purpose of the Study:
- To investigate how pneumolysin oligomerization affects lipid packing order in cholesterol-containing bilayers.
- To elucidate the stages of pore formation by analyzing changes in lipid dynamics.
Main Methods:
- Utilized optical tweezing and microfluidics to study single large-unilamellar vesicles.
- Employed Raman spectroscopy to monitor changes in lipid C-H bond vibrations.
- Analyzed changes in the Raman spectrum envelope to infer lipid packing order and rotational diffusion.
Main Results:
- A significant alteration in lipid packing order was observed during the assembly of pneumolysin pre-pore oligomers.
- No detectable change in lipid packing order occurred during initial protein binding or oligomer insertion.
- Pre-pore complexes induced a phase transition from a liquid-ordered to a fluid-liquid-disordered bilayer, with cholesterol- and protein-enriched microdomains.
Conclusions:
- Lipid packing order changes are crucial during pneumolysin pore formation, specifically during pre-pore complex assembly.
- The protein-induced membrane transformation involves creating distinct lipid microdomains.
- Understanding these lipid dynamics provides insights into the mechanism of pore formation by bacterial toxins.
More Related Videos
08:23Automated Lipid Bilayer Membrane Formation Using a Polydimethylsiloxane Thin Film
Published on: July 10, 2016
18.9K
09:30Analyzing Dynamic Protein Complexes Assembled On and Released From Biolayer Interferometry Biosensor Using Mass Spectrometry and Electron Microscopy
Published on: August 6, 2018
9.8K
Related Concept Videos
00:59Mechanisms of Membrane Domain Formation
3.7K
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with...
Another mechanism for membrane domain formation involves membrane proteins interacting with...
3.7K
01:19Formation of Lipopolysaccharides
400
Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin,...
400
01:21Structure of Porins
3.7K
Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
3.7K
01:43SNAREs and Membrane Fusion
12.1K
Once a transport vesicle has recognized its target organelle, the vesicular membrane needs to fuse with the target membrane to unload the cargo. Transmembrane proteins called SNAREs present on organelle membranes and their vesicles, mediate vesicle fusion.
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
SNAREs exist in pairs that symmetrically interact and catalyze the fusion of the lipid bilayers in vesicle and target organelle. v-SNARE in the vesicle membrane are single polypeptide chains that bind to a complementary t-SNARE, composed of 2...
12.1K
01:38Intralumenal Vesicles and Multivesicular Bodies
4.6K
Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
4.6K
01:32Pinching-off of Coated Vesicles
3.9K
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
3.9K