Biology subjects

Wadsworth, G. M.

Publications and source records attributed to Wadsworth, G. M..

3 recordsLinked to original sources

bioRxiv2025

The Critical Role of the 2'-OH group in Phase Separation and Percolation Transitions of RNA

Mg2+ ion-dependent RNA liquid-liquid phase separation with lower critical solution temperatures is driven by the phosphate backbone and modulated by the solvation property of nucleobases. Here, we report a key role of the 2-OH group of the ribose sugar in RNA condensation in the presence of divalent cations. We show that 2-deoxyribose inhibits nucleic acid phase separation and suppresses the intra-condensate networking transition, known as percolation, that underlies condensate dynamical arrest. All-atom simulations reveal increased solvation and compaction of single-stranded DNA compared to RNA, suggesting an unintuitive role of chain flexibility in modulating heat-induced nucleic acid phase separation and percolation transitions. Further, 2-O-methylation (2-O-Me) of RNA, a common sugar modification, lowers the driving force of RNA phase transitions. These results highlight the diverse physicochemical parameters governing nucleic acid phase behavior and suggest how sugar modifications may have evolved to robustly tune the formation and dynamical arrest of RNA condensates.

biophysics↗

bioRxiv2024

Biomolecular Condensates Can Enhance Pathological RNA Clustering

Intracellular aggregation of repeat expanded RNA has been implicated in many neurological disorders. Here, we study the role of biomolecular condensates on irreversible RNA clustering. We find that physiologically relevant, and disease-associated repeat RNAs spontaneously undergo an age-dependent percolation transition inside multi-component protein-nucleic acid condensates to form nanoscale clusters. Homotypic RNA clusters drive the emergence of multiphasic condensate structures, with an RNA-rich solid core surrounded by an RNA-depleted fluid shell. The timescale of the RNA clustering, which accompanies a liquid-to-solid transition of biomolecular condensates, is determined by the sequence features, stability of RNA secondary structure, and repeat length. Importantly, G3BP1, the core scaffold of stress granules, introduces heterotypic buffering to homotypic RNA-RNA interactions and impedes intra-condensate RNA clustering in an ATP-independent manner. Our work suggests that biomolecular condensates can act as sites for RNA aggregation. It also highlights the functional role of RNA-binding proteins in suppressing aberrant RNA phase transitions.

biophysics↗

bioRxiv2022

RNAs undergo phase transitions with lower critical solution temperatures

Co-phase separation of RNAs and RNA-binding proteins is thought to drive the biogenesis of ribonucleoprotein granules. RNAs can also undergo phase transitions in the absence of proteins. However, the physicochemical driving forces of protein-free, RNA-driven phase transitions remain unclear. Here, we report that RNAs of various types undergo phase transitions with system-specific lower critical solution temperatures (LCSTs). This entropically-driven phase behavior requires Mg2+ ions and is an intrinsic feature of the phosphate backbone that is modulated by RNA bases. RNA-only condensates can additionally undergo enthalpically favorable percolation transitions within dense phases. This is enabled by a combination of Mg2+-dependent bridging interactions among phosphate groups and RNA base-stacking / base-pairing. Phase separation coupled to percolation can cause dynamical arrest of RNAs within condensates and can suppress the catalytic activity of an RNase P ribozyme. Our work highlights the need to incorporate RNA-driven phase transitions into models for RNP granule biogenesis.

biophysics↗