Dynamics of Crowded Vesicles: Local and Global Responses to Membrane Composition.
The bacterial cell envelope is composed of a mixture of different lipids and proteins, making it an inherently complex organelle. The interactions between integral membrane proteins and lipids are crucial for their respective spatial localization within bacterial cells. We have employed microsecond timescale coarse-grained molecular dynamics simulations of vesicles of varying sizes and with a range of protein and lipid compositions, and used novel approaches to measure both local and global system dynamics, the latter based on spherical harmonics analysis. Our results suggest that both hydrophobic mismatch, enhanced by embedded membrane proteins, and curvature based sorting, due to different modes of undulation, may drive assembly in vesicular systems. Interestingly, the modes of undulation of the vesicles were found to be altered by the specific protein and lipid composition of the vesicle. Strikingly, lipid dynamics were shown to be coupled to proteins up to 6 nm from their surface, a substantially larger distance than has previously been observed, resulting in multi-layered annular rings enriched with particular types of phospholipid. Such large protein-lipid complexes may provide a mechanism for long-range communication. Given the complexity of bacterial membranes, our results suggest that subtle changes in lipid composition may have major implications for lipid and protein sorting under a curvature-based membrane-sorting model.
Bioinformatics Institute (A*STAR), 30 Biopolis Str, #07-01 Matrix, Singapore 138671, Singapore.|School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
Daniel A
DA
Holdbrook
Bioinformatics Institute (A*STAR), 30 Biopolis Str, #07-01 Matrix, Singapore 138671, Singapore.
Roland G
RG
Huber
The Defence Science and Technology Laboratory, Porton Down, Salisbury, SP4 0JQ, United Kingdom.|School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
Thomas J
TJ
Piggot
Bioinformatics Institute (A*STAR), 30 Biopolis Str, #07-01 Matrix, Singapore 138671, Singapore.|Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore.
Peter J
PJ
Bond
School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom.
Syma
S
Khalid
D002462:Cell Membrane / Q000378:metabolism*; D022162:Cytoplasmic Vesicles / Q000737:chemistry / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*
D008051:Lipid Bilayers; D008565:Membrane Proteins; D010710:Phosphates; D010713:Phosphatidylcholines; D010743:Phospholipids