Quantification of Weak Protein-Protein Interaction from Mobility Based Assay.

Intermolecular interactions play an essential role in the function of cellular systems. These interactions are mainly composed of strong and weak interactions. In comparison to the strong interaction, weak protein-protein interactions (PPIs) are the order of thermal energy. Such weak PPIs are critical in understanding the rapid response of cellular systems, disordered protein interactions, and liquid-liquid phase separation, to name a few. Many conventional experimental techniques characterize PPIs very precisely, but those are focused either on strong PPIs or limited to low-throughput manner.  We report on our recently developed method to quantify the weak PPIs in a high-throughput manner. Using video-microscopy, we measure the diffusion/mobility of colloids grafted with proteins over surfaces grafted with a different set of proteins. We show that such mobility assay is susceptible to minor alteration in PPIs up to a single amino acid mutation between intrinsically disordered peptides.