Seminarium

    https://zoom.us/j/91976153012?pwd=azNiMWE4UnhPN3lRQlY2UHZHOXVkQT09


   "Lipid Membrane Texture Induced by Specific Protein Binding and Receptor Clustering:
          Active Roles for Lipids in Cellular Function"

                       Jarosław Majewski, Ph. D.

    Department of Chemical & Biological Engineering at the University of New Mexico, Albuquerque, US.
    Visiting Scientist at Los Alamos National Laboratory, Los Alamos, NM, US.
    Affiliated Professor at the University of Warsaw, Poland.

                                       Bogdan Lesyng (UW)
                                       Anna Niedźwiecka (IF PAN)
                                       Piotr Zielenkiewicz (IBB)


ABSTRACT
Biological membranes are complex,
self-organized structures that define boundaries and compartmentalize space in
living matter. Composed of various lipid and protein molecules, these
responsive surfaces mediate transmembrane signaling and material transport
within the cell and with its environment. It is well known that lipid membrane
properties change as a function of composition and phase state and that
protein-lipid interactions can induce changes in the membrane’s properties and
biochemical response. Here, molecular level changes in lipid organization
induced by multivalent toxin binding were investigated using grazing incidence
X-ray diffraction. Structural changes to lipid monolayers at the air-water
interface and bilayers at the solid-water interface were studied before and
after the specific binding of cholera toxin to membrane-embedded receptors. At
biologically relevant surface pressures, protein binding perturbed lipid
packing within monolayers and bilayers resulting in topological defects and the
emergence of a new orientationally textured lipid phase. In bilayers this
altered lipid order was transmitted from the receptor-laden exterior membrane leaflet
to the inner leaflet, representing a potential mechanism for lipid-mediated
outside-in signaling by multivalent protein binding. It is further hypothesized
that cell surface micro-domains exhibiting this type of lipid order may serve
as nucleation sites for vesicle formation in clathrin-independent endocytosis
of cholera toxin.