1
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Li SF, Muthukumar M. Theory of thermoreversible gelation and anomalous concentration fluctuations in polyzwitterion solutions. J Chem Phys 2024; 161:024903. [PMID: 38990120 DOI: 10.1063/5.0216981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 06/24/2024] [Indexed: 07/12/2024] Open
Abstract
We present a theoretical framework to investigate thermoreversible phase transitions within polyzwitterion systems, encompassing macrophase separations (MPS) and gelation. In addition, we explore concentration fluctuations near critical points associated with MPS, as well as tricritical and bicritical points at the intersection of MPS and gelation. By utilizing mean-field percolation theory and field theory formalism, we derive the Landau free energy in terms of polyzwitterion concentration with fixed dipole strengths and other experimental variables, such as temperatures and salt concentrations. As the temperature decreases, the dipoles can form cross-links, resulting in polyzwitterion associations. The associations can grow to a gel network and enhance the propensity for MPS, including liquid-liquid, liquid-gel, and gel-gel phase separations. Remarkably, the associations also impact critical behaviors. Using the renormalization group technique, we find that the critical exponents of the polyzwitterion concentration correlation functions significantly deviate from those in the Ising universality class due to the presence of polyzwitterion associations, leading to crossover critical behaviors.
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Affiliation(s)
- Siao-Fong Li
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Murugappan Muthukumar
- Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA
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2
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Sood A, Zhang B. Preserving condensate structure and composition by lowering sequence complexity. Biophys J 2024; 123:1815-1826. [PMID: 38824391 PMCID: PMC11267431 DOI: 10.1016/j.bpj.2024.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/25/2024] [Accepted: 05/28/2024] [Indexed: 06/03/2024] Open
Abstract
Biomolecular condensates play a vital role in organizing cellular chemistry. They selectively partition biomolecules, preventing unwanted cross talk and buffering against chemical noise. Intrinsically disordered proteins (IDPs) serve as primary components of these condensates due to their flexibility and ability to engage in multivalent interactions, leading to spontaneous aggregation. Theoretical advancements are critical at connecting IDP sequences with condensate emergent properties to establish the so-called molecular grammar. We proposed an extension to the stickers and spacers model, incorporating heterogeneous, nonspecific pairwise interactions between spacers alongside specific interactions among stickers. Our investigation revealed that although spacer interactions contribute to phase separation and co-condensation, their nonspecific nature leads to disorganized condensates. Specific sticker-sticker interactions drive the formation of condensates with well-defined networked structures and molecular composition. We discussed how evolutionary pressures might emerge to affect these interactions, leading to the prevalence of low-complexity domains in IDP sequences. These domains suppress spurious interactions and facilitate the formation of biologically meaningful condensates.
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Affiliation(s)
- Amogh Sood
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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3
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Jeong H, Gu J, Mwasame P, Patankar K, Yu D, Sing CE. Modeling the competition between phase separation and polymerization under explicit polydispersity. SOFT MATTER 2024; 20:681-692. [PMID: 38164983 DOI: 10.1039/d3sm01411h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The dynamics of phase separation for polymer blends is important in determining the final morphology and properties of polymer materials; in practical applications, this phase separation can be controlled by coupling to polymerization reaction kinetics via a process called 'polymerization-induced phase separation'. We develop a phase-field model for a polymer melt blend using a polymerizing Cahn-Hilliard (pCH) formalism to understand the fundamental processes underlying phase separation behavior of a mixture of two species independently undergoing linear step-growth polymerization. In our method, we explicitly model polydispersity in these systems to consider different molecular-weight components that will diffuse at different rates. We first show that this pCH model predicts results consistent with the Carothers predictions for step-growth polymerization kinetics, the Flory-Huggins theory of polymer mixing, and the classical predictions of spinodal decomposition in symmetric polymer blends. The model is then used to characterize (i) the competition between phase separation dynamics and polymerization kinetics, and (ii) the effect of unequal reaction rates between species. For large incompatibility between the species (i.e. high χ), our pCH model demonstrates that the strength for phase separation directly corresponds to the kinetics of phase separation. We find that increasing the reaction rate k̃, first induces faster phase separation but this trend reverses as we further increase k̃ due to the competition between molecular diffusion and polymerization. In this case, phase separation is delayed for faster polymerization rates due to the rapid accumulation of slow-moving, high molecular weight components.
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Affiliation(s)
- Hyeonmin Jeong
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Junsi Gu
- Dow Chemical Company, Midland, MI, 48667, USA
| | | | | | - Decai Yu
- Dow Chemical Company, Midland, MI, 48667, USA
| | - Charles E Sing
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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4
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Chalykh AE, Gerasimov VK, Petrova TF, Shcherbina AA. Determination of Pair Interaction Parameters of Multicomponent Polymer Systems. Polymers (Basel) 2023; 16:68. [PMID: 38201732 PMCID: PMC10780505 DOI: 10.3390/polym16010068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/18/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
From the examples of three and four-component polymer-polymer systems characterized by amorphous separation, an original technique for determining the pair parameters of interaction between components based on the sorption isotherms of common solvent vapor, particularly water vapor, has been developed. The possibility of calculating thermodynamic characteristics of multicomponent polymer compositions with specific interactions of functional groups from experimentally obtained sorption isotherms is shown. An algorithm for calculating pair interaction parameters, estimating concentration dependences of chemical potential and Gibbs free energy of mixing, and predicting the phase state of polymer mixtures was presented for the first time for such systems. The technique was tested on the example of systems poly(N-vinylpyrrolidone) (PNVP)-polyethylene glycol (PEG), PNVP-PEG-Poly(acrylic acid) (PAA), poly(N-vinylcaprolactam) (PNVCL)-PEG, and polyvinyl alcohol (PVA)-PEG.
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Affiliation(s)
- Anatoly E. Chalykh
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences (IPCE RAS), 31, bld.4 Leninsky Prospect, Moscow 119071, Russia
| | - Vladimir K. Gerasimov
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences (IPCE RAS), 31, bld.4 Leninsky Prospect, Moscow 119071, Russia
| | - Tatiana F. Petrova
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences (IPCE RAS), 31, bld.4 Leninsky Prospect, Moscow 119071, Russia
| | - Anna A. Shcherbina
- Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences (IPCE RAS), 31, bld.4 Leninsky Prospect, Moscow 119071, Russia
- Mendeleev University of Chemical Technology, Advanced Engineering School of Chemical Engineering and Machinery, 9 Miusskaya Square, Moscow 125047, Russia
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5
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Sood A, Zhang B. Preserving condensate structure and composition by lowering sequence complexity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.29.569249. [PMID: 38076908 PMCID: PMC10705451 DOI: 10.1101/2023.11.29.569249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Biological condensates play a vital role in organizing cellular chemistry. They selectively partition biomolecules, preventing unwanted cross-talk and buffering against chemical noise. Intrinsically disordered proteins (IDPs) serve as primary components of these condensates due to their flexibility and ability to engage in multivalent, non-specific interactions, leading to spontaneous aggregation. Theoretical advancements are critical at connecting IDP sequences with condensate emergent properties to establish the so-called molecular grammar. We proposed an extension to the stickers and spacers model, incorporating non-specific pairwise interactions between spacers alongside specific interactions among stickers. Our investigation revealed that while spacer interactions contribute to phase separation and co-condensation, their non-specific nature leads to disorganized condensates. Specific sticker-sticker interactions drive the formation of condensates with well-defined structures and molecular composition. We discussed how evolutionary pressures might emerge to affect these interactions, leading to the prevalence of low complexity domains in IDP sequences. These domains suppress spurious interactions and facilitate the formation of biologically meaningful condensates.
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Affiliation(s)
- Amogh Sood
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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6
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Alston JJ, Soranno A. Condensation Goes Viral: A Polymer Physics Perspective. J Mol Biol 2023; 435:167988. [PMID: 36709795 PMCID: PMC10368797 DOI: 10.1016/j.jmb.2023.167988] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/18/2023] [Accepted: 01/21/2023] [Indexed: 01/27/2023]
Abstract
The past decade has seen a revolution in our understanding of how the cellular environment is organized, where an incredible body of work has provided new insights into the role played by membraneless organelles. These rapid advancements have been made possible by an increasing awareness of the peculiar physical properties that give rise to such bodies and the complex biology that enables their function. Viral infections are not extraneous to this. Indeed, in host cells, viruses can harness existing membraneless compartments or, even, induce the formation of new ones. By hijacking the cellular machinery, these intracellular bodies can assist in the replication, assembly, and packaging of the viral genome as well as in the escape of the cellular immune response. Here, we provide a perspective on the fundamental polymer physics concepts that may help connect and interpret the different observed phenomena, ranging from the condensation of viral genomes to the phase separation of multicomponent solutions. We complement the discussion of the physical basis with a description of biophysical methods that can provide quantitative insights for testing and developing theoretical and computational models.
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Affiliation(s)
- Jhullian J Alston
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA; Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA; Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA.
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7
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Macias E, Travesset A. Hydrogen Bond Network Disruption by Hydration Layers in Water Solutions with Salt and Hydrogen-Bonding Polymers (PEO). J Phys Chem B 2023. [PMID: 37478338 DOI: 10.1021/acs.jpcb.3c02505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
A mean field theory model describing the interaction of ion hydration layers with the network of hydrogen bonds of both water and the nonionic polymer poly(ethylene oxide) (PEO) is presented. The predictions of the model for types and statistics of hydrogen bonds, the number of water molecules bound to PEO, or their dependence on temperature are successfully verified from all-atom simulations at different NaCl and PEO concentrations. Furthermore, our simulations show that the binding of cations to PEO increases monotonically with salt concentration, in agreement with recent experimental results, through a mechanism in which the sum of the number of bound water and cations is independent of salt concentration. The model introduced is general and can describe any salt or hydrogen-bond-forming polymer.
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Affiliation(s)
- Elizabeth Macias
- Department of Physics and Astronomy, Iowa State University and Ames Lab, Ames, Iowa 50011, United States
| | - Alex Travesset
- Department of Physics and Astronomy, Iowa State University and Ames Lab, Ames, Iowa 50011, United States
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8
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Xiang YX, Shan Y, Lei QL, Ren CL, Ma YQ. Dynamics of protein condensates in weak-binding regime. Phys Rev E 2022; 106:044403. [PMID: 36397514 DOI: 10.1103/physreve.106.044403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023]
Abstract
Weak complementary interactions between proteins and nucleic acids are the main driving forces of intracellular liquid-liquid phase separation. The sticker-spacer model has emerged as a unifying principle for understanding the phase behavior of these multivalent molecules. It remains elusive how specific interactions mediated by stickers contribute to the rheological properties of the liquid condensates. Previous studies have revealed that for strong binding strength ɛ_{b}, the bulk diffusivity D depends on the effective bond lifetime τ, viz., D∝τ^{-1}. Consequently, equal concentrations of the complementary stickers induce a slow down in the dynamics of the condensates D∝e^{-1.5ɛ_{b}}. However, for weak-binding strength, it is expected that the resulting condensates are dynamic, loose network liquids rather than kinetically arrested, compact clusters. We develop a mean-field theory using the thermodynamics of the associative polymers and perform molecular-dynamics simulations based on the sticker-spacer model to study the controlling factors in the structure and dynamics of such condensates in the weak-binding regime. Through scaling analysis, we delineate how the free sticker fraction W_{f} and the bulk diffusivity D decrease with increasing binding energy and find that the internal dynamics of such network liquids are controlled by the free sticker fraction D∝W_{f}∝e^{-0.5ɛ_{b}} rather than the effective bond lifetime. Referred to as the free-sticker-dominated diffusivity, the microscopic slowdown due to a gradual loss of the free stickers affects the viscosity of the condensates as well, with the scaling of the zero-shear viscosity η∝e^{0.5ɛ_{b}}. Therefore, the way of controlling the structure, diffusivity, and viscosity of the condensates through the binding energy can be tested experimentally.
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Affiliation(s)
- Ya-Xin Xiang
- National Laboratory of Solid State Microstructures and Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yue Shan
- National Laboratory of Solid State Microstructures and Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Qun-Li Lei
- National Laboratory of Solid State Microstructures and Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chun-Lai Ren
- National Laboratory of Solid State Microstructures and Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yu-Qiang Ma
- National Laboratory of Solid State Microstructures and Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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9
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Inclusion/Exclusion Behaviors of Small Molecules during Crystallization of Polymers in Miscible PLLA/TAIC Blend. Polymers (Basel) 2022; 14:polym14132737. [PMID: 35808781 PMCID: PMC9269167 DOI: 10.3390/polym14132737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 06/15/2022] [Accepted: 06/29/2022] [Indexed: 11/29/2022] Open
Abstract
In this work, PLLA/TAIC has been taken as a model system to investigate the inclusion and exclusion of small molecules during the crystallization of polymers in their miscible blend. Our results indicate that it is the growth rate and diameter of PLLA spherulites that dominate the localization of TAIC. On the one hand, crystallization temperature plays an important role. Crystallization at higher temperature corresponds to higher growth rates and a greater diameter of PLLA spherulites. The former improves the ability of PLLA crystals to trap TAIC while the latter leads to a lower volume fraction of space among neighboring PLLA spherulites. The combination of the two contributes to the enhanced inclusion behaviors. On the other hand, when compared to melt crystallization, cold crystallization results in much smaller spherulites (from higher nucleation density) and sufficient space among spherulites, which accounts for the enrichment of TAIC in interspherulitic regions and for its enhanced exclusion. In the adopted polymer–small molecule blend, TAIC can enrich in interspherulitic regions even in its miscible blend with PLLA, which can be attributed to its stronger diffusion ability.
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10
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Michels JJ, Brzezinski M, Scheidt T, Lemke EA, Parekh SH. Role of Solvent Compatibility in the Phase Behavior of Binary Solutions of Weakly Associating Multivalent Polymers. Biomacromolecules 2022; 23:349-364. [PMID: 34866377 PMCID: PMC8753604 DOI: 10.1021/acs.biomac.1c01301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/23/2021] [Indexed: 11/29/2022]
Abstract
Condensate formation of biopolymer solutions, prominently those of various intrinsically disordered proteins (IDPs), is often driven by "sticky" interactions between associating residues, multivalently present along the polymer backbone. Using a ternary mean-field "stickers-and-spacers" model, we demonstrate that if sticker association is of the order of a few times the thermal energy, a delicate balance between specific binding and nonspecific polymer-solvent interactions gives rise to a particularly rich ternary phase behavior under physiological circumstances. For a generic system represented by a solution comprising multiassociative scaffold and client polymers, the difference in solvent compatibility between the polymers modulates the nature of isothermal liquid-liquid phase separation (LLPS) between associative and segregative. The calculations reveal regimes of dualistic phase behavior, where both types of LLPS occur within the same phase diagram, either associated with the presence of multiple miscibility gaps or a flip in the slope of the tie-lines belonging to a single coexistence region.
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Affiliation(s)
- Jasper J. Michels
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mateusz Brzezinski
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Tom Scheidt
- Institute
for Molecular Biology, Johannes Gutenberg
University, Ackermannweg
4, 55128 Mainz, Germany
| | - Edward A. Lemke
- Institute
for Molecular Biology, Johannes Gutenberg
University, Ackermannweg
4, 55128 Mainz, Germany
| | - Sapun H. Parekh
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Department
of Biomedical Engineering, The University
of Texas at Austin, 107
West Dean Keeton Street Stop C0800, Austin, Texas 78712, United States
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11
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Ryu JK, Hwang DE, Choi JM. Current Understanding of Molecular Phase Separation in Chromosomes. Int J Mol Sci 2021; 22:10736. [PMID: 34639077 PMCID: PMC8509192 DOI: 10.3390/ijms221910736] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular phase separation denotes the demixing of a specific set of intracellular components without membrane encapsulation. Recent studies have found that biomolecular phase separation is involved in a wide range of cellular processes. In particular, phase separation is involved in the formation and regulation of chromosome structures at various levels. Here, we review the current understanding of biomolecular phase separation related to chromosomes. First, we discuss the fundamental principles of phase separation and introduce several examples of nuclear/chromosomal biomolecular assemblies formed by phase separation. We also briefly explain the experimental and computational methods used to study phase separation in chromosomes. Finally, we discuss a recent phase separation model, termed bridging-induced phase separation (BIPS), which can explain the formation of local chromosome structures.
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Affiliation(s)
- Je-Kyung Ryu
- Department of Biological Sciences, KAIST, Daejeon 34141, Korea
| | - Da-Eun Hwang
- Department of Chemistry, Pusan National University, Busan 46241, Korea;
| | - Jeong-Mo Choi
- Department of Chemistry, Pusan National University, Busan 46241, Korea;
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12
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Bercea M, Gradinaru LM, Barbalata-Mandru M, Vlad S, Nita LE, Plugariu IA, Albulescu R. Shear flow of associative polymers in aqueous solutions. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130441] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Ruff KM, Dar F, Pappu RV. Polyphasic linkage and the impact of ligand binding on the regulation of biomolecular condensates. BIOPHYSICS REVIEWS 2021; 2:021302. [PMID: 34179888 PMCID: PMC8211317 DOI: 10.1063/5.0050059] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/11/2021] [Indexed: 12/30/2022]
Abstract
Cellular matter can be spatially and temporally organized into membraneless biomolecular condensates. The current thinking is that these condensates form and dissolve via phase transitions driven by one or more condensate-specific multivalent macromolecules known as scaffolds. Cells likely regulate condensate formation and dissolution by exerting control over the concentrations of regulatory molecules, which we refer to as ligands. Wyman and Gill introduced the framework of polyphasic linkage to explain how ligands can exert thermodynamic control over phase transitions. This review focuses on describing the concepts of polyphasic linkage and the relevance of such a mechanism for controlling condensate formation and dissolution. We describe how ligand-mediated control over scaffold phase behavior can be quantified experimentally. Further, we build on recent studies to highlight features of ligands that make them suppressors vs drivers of phase separation. Finally, we highlight areas where advances are needed to further understand ligand-mediated control of condensates in complex cellular environments. These advances include understanding the effects of networks of ligands on condensate behavior and how ligands modulate phase transitions controlled by different combinations of homotypic and heterotypic interactions among scaffold macromolecules. Insights gained from the application of polyphasic linkage concepts should be useful for designing novel pharmaceutical ligands to regulate condensates.
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Affiliation(s)
- Kiersten M. Ruff
- Department of Biomedical Engineering and Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Furqan Dar
- Department of Physics, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Rohit V. Pappu
- Department of Biomedical Engineering and Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri 63130, USA
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14
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Zhang Y, Xu B, Weiner BG, Meir Y, Wingreen NS. Decoding the physical principles of two-component biomolecular phase separation. eLife 2021; 10:62403. [PMID: 33704061 PMCID: PMC7952089 DOI: 10.7554/elife.62403] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 02/18/2021] [Indexed: 01/02/2023] Open
Abstract
Cells possess a multiplicity of non-membrane-bound compartments, which form via liquid-liquid phase separation. These condensates assemble and dissolve as needed to enable central cellular functions. One important class of condensates is those composed of two associating polymer species that form one-to-one specific bonds. What are the physical principles that underlie phase separation in such systems? To address this question, we employed coarse-grained molecular dynamics simulations to examine how the phase boundaries depend on polymer valence, stoichiometry, and binding strength. We discovered a striking phenomenon – for sufficiently strong binding, phase separation is suppressed at rational polymer stoichiometries, which we termed the magic-ratio effect. We further developed an analytical dimer-gel theory that confirmed the magic-ratio effect and disentangled the individual roles of polymer properties in shaping the phase diagram. Our work provides new insights into the factors controlling the phase diagrams of biomolecular condensates, with implications for natural and synthetic systems.
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Affiliation(s)
- Yaojun Zhang
- Center for the Physics of Biological Function, Princeton University, Princeton, United States
| | - Bin Xu
- Department of Physics, Princeton University, Princeton, United States
| | - Benjamin G Weiner
- Department of Physics, Princeton University, Princeton, United States
| | - Yigal Meir
- Department of Physics, Princeton University, Princeton, United States.,Department of Physics, Ben Gurion University of the Negev, Beersheba, Israel.,Department of Molecular Biology, Princeton University, Princeton, United States
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, United States.,Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
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15
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Du WT, Orabi EA, Mohamed MG, Kuo SW. Inter/intramolecular hydrogen bonding mediate miscible blend formation between near-perfect alternating Poly(styrene-alt- hydroxyphenylmaleimide) copolymers and Poly(vinyl pyrrolidone). POLYMER 2021. [DOI: 10.1016/j.polymer.2021.123542] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Choi JM, Hyman AA, Pappu RV. Generalized models for bond percolation transitions of associative polymers. Phys Rev E 2020; 102:042403. [PMID: 33212590 PMCID: PMC10846689 DOI: 10.1103/physreve.102.042403] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/17/2020] [Indexed: 04/12/2023]
Abstract
Polymers with stickers-and-spacers architectures can drive phase-separation-aided bond percolation transitions. Here, we present a generalized mean-field model to enable the calculation of bond percolation thresholds for polymers with multiple types of stickers. Further, using graph-based Monte Carlo simulations we demonstrate how cooperativity in bond formation can give rise to reentrant phase behavior. When combined with recent advances for modeling phase separation, our approaches for calculating percolation lines could be useful for modeling hardening transitions for multivalent proteins.
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Affiliation(s)
- Jeong-Mo Choi
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, United States
- Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO 63130, United States
- Natural Science Research Institute, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 31414, Republic of Korea
- Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea
| | - Anthony A. Hyman
- Max-Planck-Institut für Zellbiologie und Genetik, Pfotenhauerstraße 108, 01307 Dresden, Germany
- Center for Systems Biology Dresden, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Rohit V. Pappu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, United States
- Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO 63130, United States
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17
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Abstract
Many biomolecular condensates appear to form via spontaneous or driven processes that have the hallmarks of intracellular phase transitions. This suggests that a common underlying physical framework might govern the formation of functionally and compositionally unrelated biomolecular condensates. In this review, we summarize recent work that leverages a stickers-and-spacers framework adapted from the field of associative polymers for understanding how multivalent protein and RNA molecules drive phase transitions that give rise to biomolecular condensates. We discuss how the valence of stickers impacts the driving forces for condensate formation and elaborate on how stickers can be distinguished from spacers in different contexts. We touch on the impact of sticker- and spacer-mediated interactions on the rheological properties of condensates and show how the model can be mapped to known drivers of different types of biomolecular condensates.
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Affiliation(s)
- Jeong-Mo Choi
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, 63130, USA; , ,
- Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri, 63130, USA
- Natural Science Research Institute, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Alex S Holehouse
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, 63130, USA; , ,
- Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri, 63130, USA
| | - Rohit V Pappu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, 63130, USA; , ,
- Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, Missouri, 63130, USA
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18
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Wu JB, Liu H, Lu ZY. Simulation Study of Process-Controlled Supramolecular Block Copolymer Phase Separation with Reversible Reaction Algorithm. Polymers (Basel) 2020; 12:E528. [PMID: 32121599 PMCID: PMC7182871 DOI: 10.3390/polym12030528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 11/30/2022] Open
Abstract
A supramolecular diblock copolymer formed by reversible bonds between the two blocks shows a rich microphase separation behavior and has great application potential in stimuli-responsive materials. We propose a novel method to describe supramolecular reactions in dissipative particle dynamics, which includes a reversible reaction to accurately reproduce the strength, saturation, and dynamic properties of the reversible bonds in the simulations. The thermodynamic properties and dynamic processes of the supramolecular diblock copolymer melts in both equilibrium and non-equilibrium states were studied using this method. The simulation results show that the method can faithfully characterize phase behaviors and dynamic properties of supramolecular diblock copolymer melts, especially in a non-equilibrium state, which provides a novel tool to unveil self-assembly mechanism and describe the properties of supramolecular block copolymers.
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Affiliation(s)
- Jian-Bo Wu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China;
- State Key Laboratory of High-Efficiency Coal Utilization and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China
| | - Hong Liu
- Key Laboratory of Theoretical Chemistry of Environment Ministry of Education, School of Chemistry, South China Normal University, Guangzhou 510631, China
| | - Zhong-Yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China;
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19
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Vidal F, Gomezcoello J, Lalancette RA, Jäkle F. Lewis Pairs as Highly Tunable Dynamic Cross-Links in Transient Polymer Networks. J Am Chem Soc 2019; 141:15963-15971. [DOI: 10.1021/jacs.9b07452] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Fernando Vidal
- Department of Chemistry, Rutgers University—Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - John Gomezcoello
- Department of Chemistry, Rutgers University—Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Roger A. Lalancette
- Department of Chemistry, Rutgers University—Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Frieder Jäkle
- Department of Chemistry, Rutgers University—Newark, 73 Warren Street, Newark, New Jersey 07102, United States
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20
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Han X, Liang X, Cai L, He A, Nie H. Amphiphilic Janus nanosheets by grafting reactive rubber brushes for reinforced rubber materials. Polym Chem 2019. [DOI: 10.1039/c9py00863b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
An amphiphilic Janus nanosheet with different reactive rubber brushes on two opposite sides can simultaneously strengthen and toughen rubber blends.
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Affiliation(s)
- Xiao Han
- Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization
- Key Laboratory of Rubber-Plastics (Ministry of Education)
- School of Polymer Science and Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Xincheng Liang
- Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization
- Key Laboratory of Rubber-Plastics (Ministry of Education)
- School of Polymer Science and Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Lei Cai
- Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization
- Key Laboratory of Rubber-Plastics (Ministry of Education)
- School of Polymer Science and Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Aihua He
- Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization
- Key Laboratory of Rubber-Plastics (Ministry of Education)
- School of Polymer Science and Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
| | - Huarong Nie
- Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization
- Key Laboratory of Rubber-Plastics (Ministry of Education)
- School of Polymer Science and Engineering
- Qingdao University of Science and Technology
- Qingdao 266042
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21
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Zhang J, Mukherji D, Kremer K, Daoulas KC. Studying polymer solutions with particle-based models linked to classical density functionals: co-non-solvency. SOFT MATTER 2018; 14:9282-9295. [PMID: 30403244 DOI: 10.1039/c8sm01358f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We demonstrate the potential of hybrid particle-based models, where interactions are introduced through functionals of local order parameters, in describing multicomponent polymer solutions. The link to a free-energy-like functional is advantageous for controlling the thermodynamics of the model. We focus on co-non-solvency - the collapse of polymer chains in dilute mixtures with two miscible good solvents, having different affinities towards the polymer. We employ a simple model where polymers and solvents are represented, respectively, by worm-like chains and single particles. Non-bonded interactions are captured by a polynomial which is third order in local densities and can, therefore, describe liquid-vapour coexistence. The parameterisation of the functional benefits from an elementary mean-field approximation to the statistical mechanics of the model. The model provides a framework for Monte Carlo simulations using a particle-to-mesh algorithm. Studies with conventional generic bead-spring and all-atom models have demonstrated that co-non-solvency is caused by preferential binding of the better solvent (termed cosolvent) with polymer. Hence, segmental loops bridged by cosolvent molecules are formed, initiating polymer collapse. The mesoscopic hybrid model differs conceptually from the conventional microscopic descriptions. Yet, it reproduces the same co-non-solvency mechanism supporting its universality. Films of adsorbed ternary solutions, showing co-non-solvency in the dilute regime, are considered at high concentrations. In this case, chains do not collapse. The properties of loops and tails of the adsorbed polymer agree with early theoretical predictions obtained for concentrated binary solutions.
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Affiliation(s)
- Jianguo Zhang
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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