Biophysical Society Conference | Tahoe 2024

Molecular Biophysics of Membranes

Poster Abstracts

2-POS Board 11 EXPLORING TWO-DIMENSIONAL PROTEIN-PROTEIN INTERACTIONS IN SUPPORTED LIPID BILAYERS IN PRESENCE OF SMALL ORGANIC MOLECULES Rahul Benani 1 ; Paul Cremer 1,2 ; 1 The Pennsylvania State University, Department of Chemistry, University Park, PA, USA 2 The Pennsylvania State University, Department of Biochemistry and Molecular Biology, University Park, PA, USA Membrane-associated proteins are a major component of plasma membranes and other cellular organelles. Herein, we used biotinylated binding sites to anchor avidin, a positively charged protein, and streptavidin, a negatively charged protein, to the surface of two-dimensionally fluid phospholipid membranes with phosphatidylcholine as the major component. Both the protein and lipid molecules could be labeled with dye molecules and studied inside polydimethylsiloxane (PDMS) on glass microfluidic devices. Studies were performed as a function of pH, salt concentration, as well as in the presence of small molecules, like osmolytes and denaturants, such as urea. The results showed a surprisingly variety of protein-protein interaction (PPI) behaviors. Fluorescence recovery after photobleaching (FRAP) was employed to monitor both protein and lipid diffusion as local population densities. The results revealed that protein diffusion behavior can change in a complex fashion and strongly depends not only on the exact buffer conditions and surface protein densities, but also on the presence of sugars, amino acids and osmolytes in the solution that can drastically alter PPI under what would otherwise appear to be identical conditions. These results are explained in terms of disrupting sites that enhance or impede PPI.

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