Type
Text
Type
Dissertation
Advisor
London, Erwin | Bowen, Mark | Scarlata, Suzanne | Thanassi, David.
Date
2016-12-01
Keywords
flip-flop, insertion, juxtamembrane, lipid asymmetry, TM/non-TM interconversion, transmembrane peptide | Biophysics -- Biomedical engineering -- Molecular biology
Department
Department of Physiology and Biophysics
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76746
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Cell membranes are a complex mixture often composed of approximately equal parts lipid and protein molecules. Lipids are amphipathic, having polar headgroups that prefer to associate with water and hydrophobic tails that self-associate away from water. As a result, the lipids in cell membranes exist in the form of a lipid bilayer, with lipid polar headgroups facing outwards towards water and tails grouped together in the middle. Proteins embedded in this bilayer facilitate the movement of molecules across this barrier. The molecules that form the membrane have an asymmetric distribution, with different lipids being preferentially found on one side of the bilayer or the other and membrane proteins having a definite, defined orientation. In this work, we investigated how lipid and protein structure either assist or hinder their movement across the lipid bilayer. Using simple peptides as models for proteins, we have shown that peptides accelerate the transleaflet movement (flip-flop) of lipids across the lipid bilayer in a time- and sequence-dependent manner. We also investigated the effect of polar amino acid residues located in the membrane, and the effect of different types of lipids of the rate of flip-flop. In a second study, we investigated what polar sequences at the ends of hydrophobic peptides were able allow the peptide to move across membranes, or retarded such movements. We found that peptides with relatively large and polar sequences attached at their ends were able to pass through a biologically relevant membrane rapidly, i.e. in less than 10 sec. The amount of cholesterol limited peptide movement across the bilayer, but even then only at a detectable level for the peptide with the longest, and most polar end sequence. These results have implications membrane protein maturation, and mode of membrane penetration for certain toxins, and for control of protein and lipid localization in our new asymmetric membrane preparations, which mimic cell membranes more closely than prior artificial membranes. | 114 pages
Recommended Citation
LeBarron, Jamie, "Transverse Movements of the Components of the Lipid Bilayer" (2016). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2627.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2627