Short peptide-grafted interfaces regulate protein cluster coacervation.

The behavior of protein condensates driven by weak multivalent interactions has been extensively studied in bulk systems, yet their interfacial behavior remains far less explored. Using coarse-grained simulations, we investigated protein clusters adsorbed onto interfaces grafted with short peptides through weak multivalent interactions. We found that interface-mediated coarsening and fusion significantly enhance the coacervation of clusters into condensates. Moreover, the mobility of the grafted peptides plays a key role in determining condensate behavior: On interfaces with immobile peptides, increasing surface coverage drives a transition from dewetting to partial wetting, whereas on interfaces with mobile peptides, partial wetting is more likely to occur. Importantly, the weak protein-interface interactions do not impair the dynamic molecular exchange between the condensates and the surrounding solution. Our study provides valuable insights into how protein condensates behave at biological interfaces.