Multiplexed Analysis of Multicomponent Biomolecular Condensates without Any Tag

Biomolecular condensates, formed in the process of liquid-liquid phase separation (LLPS), play key roles in RNA metabolism and cellular organization. These dynamic assemblies often contain several components, such as proteins and RNAs. Experimental methods to study biological condensates commonly involve fluorophore-labeling of various droplet components, which may affect phase separation behavior and are thus not able to probe biomolecules in their chemically native state. Here, we introduce a noninvasive, multiplexed NMR approach that enables selective observation of multiple components in hydrogel-stabilized biphasic condensates without using tags. The introduced multiplexing filter combines enhanced spin-spin cross-relaxation in the condensed phase with diffusion and isotope filters to resolve signals from distinct protein pools from both the dilute and condensed phases. We demonstrate the robust performance of this 1D ¹H NMR experiment using biphasic samples containing condensates of FUS N-terminal domain, FUS full-length, and the multicomponent condensate formed by two intrinsically disordered regions of hnRNPC1 protein with highly overlapping resonances. Integrating the multiplexing filter into multidimensional experiments enables site-specific structural and dynamic insights from diverse protein populations, extending NMR applications in LLPS.