It is proposed to investigative, using experiments and computer simulations, the unassisted permeation of short peptides through phospholipid membranes. Peptide Passive Translocations (PPT) are relevant to key questions in biology: (i) PPT suggest transport mechanisms into and out of primordial cells; (ii) PPT participate in insertion of transmembrane helices and membrane machinery; and (iii) PPT are models for the design of efficient permeants for molecular delivery. Studying kinetics and thermodynamics of peptide-membrane processes using atomically detailed physics- based approaches will provide unprecedented insight into permeation and insertion events and to the way biological systems control concentrations gradients and transport. In particular the present study may provide useful guidelines for the design of efficient molecular permeants. However, these investigations are challenging since they are impacted by (i) subtle variations in properties of the membranes and permeants, requiring high accuracy; by (ii) interactions at length scales significantly larger than the permeant dimension requiring large scale simulations; and by (iii) exceptionally broad temporal scales from nanoseconds to hours. Novel experiments and theories will address these challenges. Experimental permeation rates are determined by time- resolved absorption and fluorescence spectroscopy of tryptophan and FRET using chromophores placed strategically throughout the membrane-peptide system. Molecular Dynamics (MD) and Milestoning simulations of these systems, which closely mimic biological environments, will be conducted. We start our joint experimental-theoretical collaboration with a transmembrane helix, and continue to investigate the permeation of a single amino acid through a pure DMPC or DOPC membrane. We end with peptides crossing a membrane enriched with transmembrane helices, cholesterol (chol) or 6- ketocholestanol (6ket) molecules. The last system mimics true biological environments.

Public Health Relevance

A joint computational and experimental research will probe the permeation of peptides through membranes. Peptides are used in biology to transport cargo to and from cells, and to form molecular machines embedded in membranes that are frequently drug targets. Understanding physical properties of peptide-membrane interactions is therefore of considerable interest and may lead to new treatments.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM111364-03
Application #
9502294
Study Section
Macromolecular Structure and Function D Study Section (MSFD)
Program Officer
Lyster, Peter
Project Start
2016-06-01
Project End
2020-05-31
Budget Start
2018-06-01
Budget End
2019-05-31
Support Year
3
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Texas Austin
Department
Miscellaneous
Type
Organized Research Units
DUNS #
170230239
City
Austin
State
TX
Country
United States
Zip Code
78759
Fathizadeh, Arman; Elber, Ron (2018) Ion Permeation Through a Phospholipid Membrane: Transition State, Path Splitting, and Calculation of Permeability. J Chem Theory Comput :
Valentine, Mason L; Cardenas, Alfredo E; Elber, Ron et al. (2018) Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface. Biophys J 115:1541-1551
Elber, Ron; Bello-Rivas, Juan M; Ma, Piao et al. (2017) Calculating Iso-Committor Surfaces as Optimal Reaction Coordinates with Milestoning. Entropy (Basel) 19:
Shrestha, Rebika; Anderson, Cari M; Cardenas, Alfredo E et al. (2017) Direct Measurement of the Effect of Cholesterol and 6-Ketocholestanol on the Membrane Dipole Electric Field Using Vibrational Stark Effect Spectroscopy Coupled with Molecular Dynamics Simulations. J Phys Chem B 121:3424-3436