We propose in this M2 project to setup a multiscale simulation methodology to obtain a molecular understanding of the formation and properties of PAR-triggered condensates. The project will focus on the interaction between PAR and the FUS protein. Starting from coarse grain simulations of PAR-FUS condensates, our goal will be to setup and validate a protocol for all-atom MD simulations of these systems that will allow us to reveal the molecular level structure of these condensates and illuminate the factors modulating their properties. We will pay specific attention to 1) the choice of refined force fields (including benchmark of machine-learning potentials) to characterize PAR-FUS interactions in dilute solutions; 2) the setup of an adequate enhanced strategy techniques to sample such disordered systems ; 3) validation against experimental data obtained by our collaborators.