Our laboratory is interested in the structure and
function of biological membranes. We currently have
two primary areas of focus: (1) the properties of
membrane microdomains or „rafts‰ and (2)
the cell lytic effects of antimicrobial peptides.
In the first area of interest, we are using a variety
of biophysical techniques to analyze the structure
of membrane rafts, the mechanisms by which rafts form,
and the interactions of raft and non-raft bilayers
with peptides of biological interest. Rafts, which
have been isolated from both biological membranes
and bilayers containing specific classes of lipids,
sequester specific membrane proteins and are thought
to play important roles in cellular processes such
as endocytosis, protein and lipid trafficking, and
signal transduction. We have found that the thickness
and mechanical properties of rafts are different than
typical membranes, and these differences have profound
effects on their interactions with peptides and proteins.
In the second area of focus, we are determining the
roles of membrane components in governing how specific
antimicrobial peptides lyse cells. Appreciation is
rapidly growing for the part of the innate defense
system that depends on these peptides to kill a wide
range of microbial invaders. Most of these peptides
do not act primarily on specific processes or proteins
in the invading microbe, but begin killing the microbe
by disrupting the barrier function of the cell membrane.
Specifically, their main target is the lipid bilayer
of the microbe's membrane. Because these peptides
work on basic physical properties of the membrane
bilayer to initiate cell death, microbes have difficulty
in developing resistance to these peptides. One specific
question we are addressing is the reason host eukaryotic
cells are much less sensitive to these peptides than
are bacterial cells.
