Net charge driven recruitment of supercharged GFP mutants into FUS droplets

Abstract

Liquid droplets recruit their relevant proteins and function together. Previous studies for a series of guest proteins clarified several rules of the recruitment and translational dynamics in the droplets; however, the other guest parameters such as structures, sizes, and amino-acid compositions might mask the single parameter effect. Here, we characterized the properties of GFP mutants with different charged compositions, but the same structure and size, in fused in sarcoma (FUS) droplets using single-molecule fluorescence microscopy. The recruitment of GFP mutants depended on their absolute net charge, whereas the diffusion did not. In the recruitment vs. diffusion plots, GFP mutants with large net charges were distinct from other proteins, demonstrating the importance of long-range electrostatic interaction on the recruitment.