Biomolecular condensates are membraneless hubs of condensed proteins and nucleic acids within cells, which researchers are realizing are tied to an increasing number of cellular processes and diseases. Studies of biomolecular condensate formation have uncovered layers of complexity, including their ability to behave like a viscoelastic material. However, the molecular basis for this putty-like property was unknown.
Through a multi-institution collaboration, researchers at Washington University in St. Louis, St. Jude Children’s Research Hospital and State University of New York at Buffalo examined the interaction networks within condensates to better define the rules associated with their unique material properties. Published in Nature Physics, the results quantify the timescales associated with these interactions, explaining why condensates act like a molecular putty and how they can “age” into a viscoelastic solid more akin to a rubber ball.
“Condensates have often been described as liquid-like, but their material properties can actually vary quite a bit,” explained Tanja Mittag, of the Department of Structural Biology at St. Jude, who collaborated on this research with WashU’s Rohit Pappu, PhD. “That depends on the sequences of the proteins within them and the lifetime of the interactions being formed.”
Pappu, the Gene K. Beare Distinguished Professor at the McKelvey School of Engineering, has been working with St. Jude and partners at Buffalo to establish how condensates act as reaction hubs to organize biomolecules in cells spatially.