A spoonful of disorder regulates interactions within Stress Granules and Processing Bodies

Abstract

Condensation, or liquid-like phase separation, is a phenomenon indispensable for the spatiotemporal regulation of molecules within the cell. Recent studies indicate that the composition and molecular organization of phase-separated organelles such as Stress Granules (SGs) and Processing Bodies (PBs) are highly variable and dynamic. A dense contact network involving both RNAs and proteins controls the formation of SGs and PBs and an intricate molecular architecture, at present poorly understood, guarantees that these assemblies sense and adapt to different stresses and environmental changes. Here, we investigated the physico-chemical properties of SGs and PBs components and studied the architecture of their interaction networks. We found that proteins and RNAs establishing the largest amount of contacts in SGs and PBs have distinct structural properties and intrinsic disorder is enriched in all protein-RNA, protein-protein and RNA-RNA interaction networks. The increase of disorder in proteins is accompanied by an enrichment in single-stranded regions of RNA binding partners. Our results suggest that SGs and PBs quickly assemble and disassemble through fuzzy-like dynamic contacts modulated by unfolded domains of their components. Research HighlightsO_LIWe systematically studied RNA-RNA, protein-protein and RNA-protein interaction networks in stress granules and processing bodies; C_LIO_LIRNAs enriched in stress granules and processing bodies are more single-stranded and form a large number of contacts with both proteins and RNAs; C_LIO_LIProteins in stress granules and processing bodies are less structured and contact larger amounts of single-stranded RNAs. C_LI