UC Davis

Cell adhesion is a significant biological phenomenon whereby cells communicate with each other by external stimuli. It plays a significant role in not only multicellular organisms, but also unicellular organisms such as fungi and bacteria. Giant Unilamellar Vesicles (GUVs) have been engineered and used as a simplified bottom-up model system to understand biophysics of cellular membranes by mimicking cells of interest. Membrane active peptides (MAPs) are peptides that interact with the biological membrane by fusing, adhering, pore forming, aggregating, and disrupting lipid bilayer of the membrane. Streptavidin-biotin complex represents a high affinity protein-ligand complex, with Kd at 10-14 to 10-15 M. It is a non-covalent, rapid, and specific interaction unaffected by extreme pH and temperature as it occurs in nature. In this thesis, we used this convenient molecular platform to create a tetrameric biotinylated MAPs complex. We have found that some of these tetrameric MAPs can promote adhesion of Giant Unilamellar Vesicles (GUVs) without any external force, in a highly membrane composition-specific manner. For example, one of these MAPs discovered by OBOC combinatorial method, interacts with GUVs comprised of fungal membrane composition but not those with mammalian membrane composition. We believe our GUV adhesion system represent a useful tool for synthetic biology and for studying adhesion of minimal cells. Furthermore, some of these peptides may be engineered as vehicles for membrane penetration. Others may have anti-fungal activities.