The Fused-in-Sarcoma (FUS) protein plays major role in the process of DNA repair[1]. Its ability to phase separate and stay in reversible high fluidity condensate allows partitioning of DNA and molecules for the repair process[2]. However, aging of FUS protein cause transition into irreversible solid state which has been associated with neurodegenerative diseases[3]. The implication of FUS aging to its DNA partitioning ability remains unclear and challenging to be analyze by available techniques due to its complexity of liquid and solid coexistence. Here we investigated the dynamic of DNA (137 kDa) partitioning into different degree of FUS-condensate aging. To obtain information of the dynamics, we employed spatial temporal analysis before and after DNA partitioning using newly develop Spatial Dynamic Mapping (SDM) optical technique[4]. We recorded images of FUS condensates before and after DNA partitioning in fast (high framerate) and longtime acquisition manner. From SDM analysis, we obtained heatmaps of characteristic time of the condensates. These results show that effect of partitioning of molecules into condensates is more nuance with dynamically arrested (aged) FUS condensates reverse to more liquid state after DNA partitioning. Supported with confocal microscope images analysis, we showed that aged FUS condensates fused and increased in size after DNA partitioning which are characteristics of a liquid state. These results deepen the understanding of how biomolecules activity affect condensates characteristics, showing potential of more strategies to prevent pathological liquid-to-solid transition of protein.
[1] M. Kodavati et al., Nat Commun 2024, 15, 2156.
[2] M. V. Sukhanova et al. International Journal of Molecular Sciences 2022, 23, 13200.
[3] A. Patel et al. Cell 2015, 162, 1066–1077.
[4] Y. Shen et al. Proceedings of the National Academy of Sciences 2023, 120, e2301366120.