Biomolecular condensates are important regulators of cellular compartmentalization and biochemical processes. Characterizing their material properties is critical for understanding their mechanistic roles in biology. However, probing material properties remains challenging due to the broad range of length scales, concentrations, and timescales over which condensates operate. Additionally, traditional fluorescence-based techniques such as FRAP (fluorescence recovery after photobleaching) are further limited by label-induced artifacts, as measured properties can vary depending on the fluorescent probe used. My group investigate Dhh1 condensates—condensates associated with RNA degradation and processing—using a suite of label-free methods, including optical tweezers and a newly applied approach, scanning ion conductance microscopy (SICM). We show how protein structure and RNA actively modulates condensate stiffness in a length dependent manner, as revealed by fusion dynamics and direct stiffness measurements with SICM. Our results indicate that RNA actively contributes to the sequestration, assembly, and maturation of Dhh1 condensates. We also present new insights from studying the nucleation process of these condensates. Together, these findings advance a comprehensive understanding of the material lifecycle of Dhh1 condensates and their interplay with RNA polymers.
Wayne Yang (Sun,) studied this question.