Reentrant Phase Transition Drives Dynamic Substructure Formation in Ribonucleoprotein Droplets

Banerjee, Priya R.; Milin, Anthony N.; Moosa, Mahdi Muhammad; Onuchic, Paulo L.; Deniz, Ashok A.

doi:10.1002/ange.201703191

Cited by 141 publications

(236 citation statements)

References 32 publications

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“…where n 2 is small. This limited range of attraction allows for re-entrant behavior similar to that seen for RNA condensation due to charge-charge interactions [29].…”

Section: A Spop-spop Interactions Cause the Formation Of Linear Rodsmentioning

confidence: 83%

Protein network structure enables switching between liquid and gel states

Schmit

Bouchard

Martin

et al. 2019

Preprint

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Biomolecular condensates are emerging as an important organizational principle within living cells. These condensed states are formed by phase separation, yet little is known about how material properties are encoded within the constituent molecules and how the specificity for being in different phases is established. Here we use analytic theory to explain the phase behavior of the cancer-related protein SPOP and its substrate DAXX. Binary mixtures of these molecules have a phase diagram that contains dilute liquid, dense liquid, and gel states. We show that these discrete phases appear due to a competition between SPOP-DAXX and DAXX-DAXX interactions. The stronger SPOP-DAXX interactions dominate at sub-stoichiometric DAXX concentrations leading to the formation of crosslinked gels. The theory shows that the driving force for gel formation is not the binding energy, but rather the entropy of distributing DAXX molecules on the binding sites. At high DAXX concentrations the SPOP-DAXX interactions saturate, which leads to the dissolution of the gel and the appearance of a liquid phase driven by weaker DAXX-DAXX interactions.This competition between interactions allows multiple dense phases to form in a narrow region of parameter space. We propose that the molecular architecture of phase-separating proteins governs the internal structure of dense phases, their material properties and their functions. Analytical theory can reveal these properties on the long length and time scales relevant to biomolecular condensates.

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“…where n 2 is small. This limited range of attraction allows for re-entrant behavior similar to that seen for RNA condensation due to charge-charge interactions [29].…”

Section: A Spop-spop Interactions Cause the Formation Of Linear Rodsmentioning

confidence: 83%

Protein network structure enables switching between liquid and gel states

Schmit

Bouchard

Martin

et al. 2019

Preprint

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“…This charge inversion suggests that the stoichiometry of these fuzzy protein-RNA assemblies is not fixed but varies with the mixture composition. Interestingly, we observed that sudden jumps in RNA-to-LCD stoichiometry can lead to the formation of transient hollow droplet topologies under nonequilibrium conditions (18). Although, these vacuolated structures were observed only as fleeting intermediates during reentrant dissolution of protein-RNA condensates, their occurrence nevertheless suggested that associative RNA-protein systems may have access to complex morphologies distinct from isotropic liquid droplets.…”

Section: Introductionmentioning

confidence: 82%

“…Recently, we demonstrated that RNA can mediate a reentrant phase transition of cationic ribonucleoproteins containing arginine-rich low complexity domains (LCDs) through long-range electrostatic interactions (18,19). At sub-stoichiometric regime, RNA triggers ribonucleoprotein (RNP) phase separation whereas at super-stoichiometric ratio, excess RNA leads to droplet dissolution due to charge inversion on the surface of RNP-RNA complexes (18). This charge inversion suggests that the stoichiometry of these fuzzy protein-RNA assemblies is not fixed but varies with the mixture composition.…”

Section: Introductionmentioning

confidence: 99%

Phase Transition of RNA-protein Complexes into Ordered Hollow Condensates

Alshareedah¹,

Moosa²,

Raju

et al. 2020

Preprint

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Charge driven condensation of intrinsically disordered protein-RNA complexes is ubiquitous in both natural and biomimetic systems. So far, isotropic liquid droplets are the most commonly observed topology of RNA-protein condensates in experiments and simulations. Here, by systematically studying the phase behavior of RNA-protein complexes across varied mixture compositions, we report a hollow vesicle-like condensate phase of nucleoprotein assemblies that is distinct from RNA-protein droplets. We show that these vesicular condensates are stable at specific charge disproportionate regimes within the phase diagram and are formed through the self-assembly of highly charged anisotropic protein-RNA complexes. Similar to membranes composed of amphiphilic lipids, these nucleoprotein-RNA vesicular membranes exhibit local ordering, size-dependent permeability, and selective encapsulation capacity without sacrificing their dynamic formation and dissolution in response to physicochemical stimuli. Our findings suggest that protein-RNA complexes can robustly create lipid-free vesicle-like enclosures by phase separation. Significance statementVesicular assemblies play crucial roles in subcellular organization as well as in biotechnological applications. Classically, the ability to form such assemblies were primarily assigned to lipids and lipid-like amphiphilic molecules. Here, we show that complexes of negatively charged RNAs and positively charged disordered polypeptides can form vesicle-like ordered assemblies at charge disproportionate mixture compositions. We also show that the ability to form vesicular assemblies is not specific to RNA-protein complexes, rather is generic to complexes of oppositely charged polyionic chains. We speculate that such vesicular assemblies play crucial roles in the formation of dynamic multi-layered subcellular membrane-less organelles and can be utilized to fabricate novel stimuli-responsive microscale systems.

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“…While their promotional effects have been noted in a number of studies 10,13,23,25,27,30,31,44,45,50 , their turnover into suppressors at high concentrations has also been recognized in other studies 21,34,46,49,52 . The suppressive effects of high-concentrations RNAs may explain their ability to keep ribonucleoproteins soluble 34,35 .…”

Section: Introductionmentioning

confidence: 99%

A Tug of War Between Condensate Phases in a Minimal Macromolecular System

Ghosh

Zhang

Zhou

2020

Preprint

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AbstractMembraneless organelles formed via liquid-liquid phase separation (LLPS) contain a multitude of macromolecular species. A few of these species drive LLPS while most serve as regulators. The LLPS of SH35 (S) and PRM5 (P), two oppositely charged protein constructs, was promoted by a polyanion heparin (H) but suppressed by a cationic protein lysozyme (L). Here, using these four components alone, we demonstrate complex phase behaviors associated with membraneless organelles and uncover the underlying physical rules. The S:P, S:L, and P:H binaries form droplets, but the H:L binary forms precipitates, therefore setting off a tug of water between different phases within the S:P:H:L quaternary. We observe dissolution of precipitates upon compositional change, transformation from precipitates to droplet-like condensates over time, and segregation of S:L-rich and P:H-rich foci inside droplet-like condensates. A minimal macromolecular system can thus recapitulate membraneless organelles in essential ways and provide crucial physical understanding.

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Reentrant Phase Transition Drives Dynamic Substructure Formation in Ribonucleoprotein Droplets

Cited by 141 publications

References 32 publications

Protein network structure enables switching between liquid and gel states

Protein network structure enables switching between liquid and gel states

Phase Transition of RNA-protein Complexes into Ordered Hollow Condensates

A Tug of War Between Condensate Phases in a Minimal Macromolecular System

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