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Novel changes in discoidal high density lipoprotein morphology: a molecular dynamics study.
Andrea Catte1, James C Patterson, Martin K Jones
1Department of Medicine, and Center for Computational and Structural Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Biophysical Journal
|April 4, 2006
Summary
Apolipoprotein A-I (ApoA-I) simulations reveal how high-density lipoprotein particles remodel. Smaller particles form stable structures, with lipid-binding pockets adaptable for various phospholipids.
Area of Science:
- Biochemistry
- Structural Biology
- Computational Biophysics
Background:
- High-density lipoprotein (HDL) particles are crucial for reverse cholesterol transport.
- Apolipoprotein A-I (ApoA-I) is the primary protein component of HDL, facilitating lipid binding and particle stability.
- Understanding HDL structure and dynamics is key to cardiovascular health research.
Purpose of the Study:
- To investigate the structural dynamics of discoidal HDL particles during lipid removal using molecular dynamics simulations.
- To generate atomic-resolution models of reconstituted HDL particles.
- To elucidate the relationship between particle size, lipid composition, and ApoA-I conformation.
Main Methods:
- Molecular dynamics simulations of progressively smaller discoidal HDL particles.
- Simulations involved incremental removal of palmitoyloleoylphosphatidylcholine lipids.
- Analysis of ApoA-I helical domain conformation and lipid packing.
Main Results:
- Simulated HDL particles rapidly adopted stable helical structures for ApoA-I, closely matching lipid-free crystal structures.
- Two distinct particle sizes (95 Å and 78 Å) were modeled, corresponding to in vitro reconstituted particles.
- Lipid packing varied: 100:2 particles showed minimal surfaces, while 50:2 particles featured a dynamic lipid-binding pocket.
Conclusions:
- HDL particle size reduction leads to stable ApoA-I helical conformations.
- Atomic models provide insights into the structure of reconstituted HDL particles.
- The 50:2 HDL particle structure suggests a mechanism for accommodating diverse phospholipid cargoes.