Eukaryotic Lipid Membrane Asymmetry: What a New Technique Can Tell Us about an Old Problem
Event details
| Date | 14.04.2014 |
| Hour | 12:15 |
| Speaker | Prof. John C. Conboy, University of Utah, Salt Lake City, UT (USA) |
| Location | |
| Category | Conferences - Seminars |
DISTINGUISHED LECTURE IN BIOLOGICAL ENGINEERING
Abstract:
A membrane, only two molecules thick, surrounds all cells and is responsible for controlling the passage of materials in and out of the cell in a selective manner. Our current understanding of the structure and dynamics of cellular membranes emerged in the early 1970 ’s. However, there is still much we do not know about this seemingly simple “shell” which makes life as we know it possible. A central issue in molecular biology is the movement of lipids across the cellular membrane. The translocation of lipids is involved in cell apoptosis, the viral infection of living cells, the functioning of antibiotics, antiseptics and drugs, and the regulation and growth of cells. There have been a number of studies attempting to find the putative proteins responsive for lipid transbilayer movement in eukaryotic cells. This has led to a large number of theories about the mechanism of transbilayer movement of lipids in cellular systems and the physical process by which lipid compositional asymmetry in the plasma membrane of eukaryotic cells is maintained. Using methods of classical surface chemistry coupled with nonlinear optical methods, we have developed a novel analytical approach, using sum-frequency vibrational spectroscopy (SFVS, illustrated to the right), to selectively probe lipid compositional asymmetry in a planar supported lipid bilayer. This new method allows for the detection of lipid flip-flop kinetics and compositional asymmetry without the need for a fluorescent or spin-labeled lipid species by exploiting the coherent nature of SFVS. We were the first to show that SFVS could be used to directly measurement the transbilayer movement of phospholipids in PSLBs. These studies were followed by and investigation of the effect of lipid acyl chain length on lipid flip-flop. Our investigations have continued to delve deeper into the physical nature of lipid translocation by providing the first detail analysis of the transition state thermodynamics of lipid flip-flop and an investigation of the influence of cholesterol, and integral membrane proteins on the dynamics of lipid translocation. Various aspects of our research will be discussed.
Bio:
Education:
1989-1991 B.S., University of California, Davis, Davis, CA (USA)
1991-1996 Ph.D., University of Oregon, Eugene, OR (USA)
Professional Appointments:
1996-1997 Postdoctoral Associate (Dept. of Chem., Univ. of Minnesota)
1998-2000 National Institutes of Health Post Doctoral Fellow (Dept. of Chem., Univ. of Arizona)
2000-2003 Assistant Prof., Dept. of Chem., Univ. of Utah, Salt Lake City, UT (USA)
2003-2006 Henry Eyring Assistant Prof., Dept. of Chem., Univ. of Utah, Salt Lake City, UT (USA)
2006-present Associate Professor, Dept. of Chem., Univ. of Utah, Salt Lake City, UT (USA)
Honors and Awards:
1999-2000 National Institutes of Health Post Doctoral Fellow, National Research Service Award (NRSA)
2003-2006 Henry Eyring Assistant Professor
2006-present Henry Eyring Scholar
2008 Coblentz Society Craver Award in Applied Analytical Vibrational Spectroscopy
Link to Speaker's Lab website
Link to Speaker's Eukaryotic Lipid Membrane Asymmetry: What a New Technique Can Tell Us About an Old Problem
Abstract:
A membrane, only two molecules thick, surrounds all cells and is responsible for controlling the passage of materials in and out of the cell in a selective manner. Our current understanding of the structure and dynamics of cellular membranes emerged in the early 1970 ’s. However, there is still much we do not know about this seemingly simple “shell” which makes life as we know it possible. A central issue in molecular biology is the movement of lipids across the cellular membrane. The translocation of lipids is involved in cell apoptosis, the viral infection of living cells, the functioning of antibiotics, antiseptics and drugs, and the regulation and growth of cells. There have been a number of studies attempting to find the putative proteins responsive for lipid transbilayer movement in eukaryotic cells. This has led to a large number of theories about the mechanism of transbilayer movement of lipids in cellular systems and the physical process by which lipid compositional asymmetry in the plasma membrane of eukaryotic cells is maintained. Using methods of classical surface chemistry coupled with nonlinear optical methods, we have developed a novel analytical approach, using sum-frequency vibrational spectroscopy (SFVS, illustrated to the right), to selectively probe lipid compositional asymmetry in a planar supported lipid bilayer. This new method allows for the detection of lipid flip-flop kinetics and compositional asymmetry without the need for a fluorescent or spin-labeled lipid species by exploiting the coherent nature of SFVS. We were the first to show that SFVS could be used to directly measurement the transbilayer movement of phospholipids in PSLBs. These studies were followed by and investigation of the effect of lipid acyl chain length on lipid flip-flop. Our investigations have continued to delve deeper into the physical nature of lipid translocation by providing the first detail analysis of the transition state thermodynamics of lipid flip-flop and an investigation of the influence of cholesterol, and integral membrane proteins on the dynamics of lipid translocation. Various aspects of our research will be discussed.
Bio:
Education:
1989-1991 B.S., University of California, Davis, Davis, CA (USA)
1991-1996 Ph.D., University of Oregon, Eugene, OR (USA)
Professional Appointments:
1996-1997 Postdoctoral Associate (Dept. of Chem., Univ. of Minnesota)
1998-2000 National Institutes of Health Post Doctoral Fellow (Dept. of Chem., Univ. of Arizona)
2000-2003 Assistant Prof., Dept. of Chem., Univ. of Utah, Salt Lake City, UT (USA)
2003-2006 Henry Eyring Assistant Prof., Dept. of Chem., Univ. of Utah, Salt Lake City, UT (USA)
2006-present Associate Professor, Dept. of Chem., Univ. of Utah, Salt Lake City, UT (USA)
Honors and Awards:
1999-2000 National Institutes of Health Post Doctoral Fellow, National Research Service Award (NRSA)
2003-2006 Henry Eyring Assistant Professor
2006-present Henry Eyring Scholar
2008 Coblentz Society Craver Award in Applied Analytical Vibrational Spectroscopy
Link to Speaker's Lab website
Link to Speaker's Eukaryotic Lipid Membrane Asymmetry: What a New Technique Can Tell Us About an Old Problem
Practical information
- Informed public
- Free