Related Experiment Video
Updated: Aug 10, 2026
08:23
Automated Lipid Bilayer Membrane Formation Using a Polydimethylsiloxane Thin Film
Published on: July 10, 2016
Membrane thinning effect of the beta-sheet antimicrobial protegrin
W T Heller1, A J Waring, R I Lehrer
1Department of Physics, Rice University, Houston, Texas 77251, USA.
Biochemistry
|January 8, 2000
Summary
Antimicrobial peptide protegrin-1 (PG-1) interacts with lipid bilayers in two concentration-dependent states. At low concentrations, PG-1 is inactive in the headgroup region, thinning the bilayer.
Area of Science:
- Biophysics
- Membrane Biology
- Antimicrobial Peptides
Background:
- Lipid bilayers are essential cellular structures.
- Antimicrobial peptides (AMPs) are key components of the innate immune system.
- Protegrin-1 (PG-1) is a potent AMP with a known membrane-disrupting capability.
Purpose of the Study:
- To investigate the structural states and membrane interactions of protegrin-1 (PG-1) within lipid bilayers.
- To elucidate the concentration-dependent mechanism of PG-1 action in membranes.
- To compare PG-1's membrane interaction mechanism with that of other peptides like alamethicin.
Main Methods:
- Lamellar X-ray diffraction was employed to study lipid bilayers containing PG-1.
- Oriented circular dichroism spectroscopy was used to characterize PG-1 states.
- Peptide concentration effects on bilayer structure were analyzed.
Main Results:
- PG-1 exists in two distinct states within lipid bilayers, dependent on peptide concentration.
- Below a threshold concentration, PG-1 adopts an inactive 'S state', adsorbing to the headgroup region and decreasing bilayer thickness proportionally.
- Above the threshold, PG-1's interaction with the bilayer significantly changes, indicating a concentration-gated mechanism.
Conclusions:
- PG-1 exhibits a concentration-gated mechanism of action, similar to alamethicin.
- The inactive S state of PG-1 involves adsorption to the lipid bilayer headgroup region.
- Understanding these states is crucial for developing PG-1-based antimicrobial strategies.
Related Concept Videos
01:22Protein Folding
Overview
03:03Amyloid Fibrils
Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
01:18Detergent Purification of Membrane Proteins
Detergents are used to purify the integral proteins of the membrane. The hydrophobic portion of the detergent can replace membrane phospholipids while solubilizing the membrane proteins. When detergent monomers reach a specific concentration in a solution called critical micelle concentration (CMC), they form micelles. Above CMC, the concentration of the detergent monomers remains in equilibrium with the micelle. The number of detergent monomers present in the CMC varies for each detergent, and...
01:25Protein Folding
Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
01:09Multi-pass Transmembrane Proteins and β-barrels
In multi-pass transmembrane proteins, the polypeptide chain crosses the membrane more than once. The transmembrane polypeptide chain either forms an α-helix or β-strand structure. α-Helix containing multi-pass transmembrane proteins are ubiquitous, whereas β-strand containing ones are mainly found in gram-negative bacteria, mitochondria, and chloroplasts.
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
01:23Inhibitors of Gram-positive Cell Wall Synthesis
Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...