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Mangiarotti A, Nayak A, Milovanovic D. Aberrant tau condensates as catalytic microcompartments propel tau fibrillation. Structure 2024; 32:1547-1549. [PMID: 39366336 DOI: 10.1016/j.str.2024.09.004] [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: 09/02/2024] [Revised: 09/04/2024] [Accepted: 09/04/2024] [Indexed: 10/06/2024]
Abstract
In this issue of Structure, Soeda et al.1 employed optogenetic tools and demonstrate that an N-terminal truncation of tau and microtubule-binding deficiency lead to the formation of tau condensates, accelerating its fibrillation.
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Affiliation(s)
- Agustín Mangiarotti
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Asima Nayak
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany.
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2
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Krainer G, Jacquat RPB, Schneider MM, Welsh TJ, Fan J, Peter QAE, Andrzejewska EA, Šneiderienė G, Czekalska MA, Ausserwoeger H, Chai L, Arter WE, Saar KL, Herling TW, Franzmann TM, Kosmoliaptsis V, Alberti S, Hartl FU, Lee SF, Knowles TPJ. Single-molecule digital sizing of proteins in solution. Nat Commun 2024; 15:7740. [PMID: 39231922 PMCID: PMC11375031 DOI: 10.1038/s41467-024-50825-9] [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: 07/14/2023] [Accepted: 07/23/2024] [Indexed: 09/06/2024] Open
Abstract
The physical characterization of proteins in terms of their sizes, interactions, and assembly states is key to understanding their biological function and dysfunction. However, this has remained a difficult task because proteins are often highly polydisperse and present as multicomponent mixtures. Here, we address this challenge by introducing single-molecule microfluidic diffusional sizing (smMDS). This approach measures the hydrodynamic radius of single proteins and protein assemblies in microchannels using single-molecule fluorescence detection. smMDS allows for ultrasensitive sizing of proteins down to femtomolar concentrations and enables affinity profiling of protein interactions at the single-molecule level. We show that smMDS is effective in resolving the assembly states of protein oligomers and in characterizing the size of protein species within complex mixtures, including fibrillar protein aggregates and nanoscale condensate clusters. Overall, smMDS is a highly sensitive method for the analysis of proteins in solution, with wide-ranging applications in drug discovery, diagnostics, and nanobiotechnology.
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Affiliation(s)
- Georg Krainer
- Institute of Molecular Biosciences (IMB), University of Graz, Humboldtstraße 50, 8010, Graz, Austria.
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
| | - Raphael P B Jacquat
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Matthias M Schneider
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Department of Cellular Biochemistry, Max-Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Timothy J Welsh
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Jieyuan Fan
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Quentin A E Peter
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Ewa A Andrzejewska
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Greta Šneiderienė
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Magdalena A Czekalska
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Hannes Ausserwoeger
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Lin Chai
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - William E Arter
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Kadi L Saar
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Therese W Herling
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Titus M Franzmann
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307, Dresden, Germany
| | - Vasilis Kosmoliaptsis
- Department of Surgery, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
- NIHR Blood and Transplant Research Unit in Organ Donation and Transplantation, University of Cambridge, Hills Road, Cambridge, CB2 0QQ, UK
- NIHR Cambridge Biomedical Research Centre, University of Cambridge, Hills Road, Cambridge, CB2 0QQ, UK
| | - Simon Alberti
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307, Dresden, Germany
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max-Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
- Munich Cluster for Systems Neurology (SyNergy), Feodor-Lynen-Str. 17, 81377, Munich, Germany
| | - Steven F Lee
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
- Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Ave, Cambridge, CB3 0HE, UK.
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3
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Chattaraj A, Baltaci Z, Chung S, Mayer BJ, Loew LM, Ditlev JA. Measurement of solubility product reveals the interplay of oligomerization and self-association for defining condensate formation. Mol Biol Cell 2024; 35:ar122. [PMID: 39046778 PMCID: PMC11449392 DOI: 10.1091/mbc.e24-01-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 06/06/2024] [Accepted: 07/16/2024] [Indexed: 07/25/2024] Open
Abstract
Cellular condensates often consist of 10s to 100s of distinct interacting molecular species. Because of the complexity of these interactions, predicting the point at which they will undergo phase separation is daunting. Using experiments and computation, we therefore studied a simple model system consisting of polySH3 and polyPRM designed for pentavalent heterotypic binding. We tested whether the peak solubility product, or the product of the dilute phase concentration of each component, is a predictive parameter for the onset of phase separation. Titrating up equal total concentrations of each component showed that the maximum solubility product does approximately coincide with the threshold for phase separation in both experiments and models. However, we found that measurements of dilute phase concentration include small oligomers and monomers; therefore, a quantitative comparison of the experiments and models required inclusion of small oligomers in the model analysis. Even with the inclusion of small polyPRM and polySH3 oligomers, models did not predict experimental results. This led us to perform dynamic light scattering experiments, which revealed homotypic binding of polyPRM. Addition of this interaction to our model recapitulated the experimentally observed asymmetry. Thus, comparing experiments with simulation reveals that the solubility product can be predictive of the interactions underlying phase separation, even if small oligomers and low affinity homotypic interactions complicate the analysis.
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Affiliation(s)
- Aniruddha Chattaraj
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT 06030
| | - Zeynep Baltaci
- Program in Molecular Medicine, Toronto, ON M5G 1E8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Steve Chung
- Program in Molecular Medicine, Toronto, ON M5G 1E8, Canada
| | - Bruce J. Mayer
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT 06030
- Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, CT 06030
| | - Leslie M. Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, CT 06030
| | - Jonathon A. Ditlev
- Program in Molecular Medicine, Toronto, ON M5G 1E8, Canada
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON M5G 1E8, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A1, Canada
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4
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Roden CA, Gladfelter AS. Experimental Considerations for the Evaluation of Viral Biomolecular Condensates. Annu Rev Virol 2024; 11:105-124. [PMID: 39326881 DOI: 10.1146/annurev-virology-093022-010014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2024]
Abstract
Biomolecular condensates are nonmembrane-bound assemblies of biological polymers such as protein and nucleic acids. An increasingly accepted paradigm across the viral tree of life is (a) that viruses form biomolecular condensates and (b) that the formation is required for the virus. Condensates can promote viral replication by promoting packaging, genome compaction, membrane bending, and co-opting of host translation. This review is primarily concerned with exploring methodologies for assessing virally encoded biomolecular condensates. The goal of this review is to provide an experimental framework for virologists to consider when designing experiments to (a) identify viral condensates and their components, (b) reconstitute condensation cell free from minimal components, (c) ask questions about what conditions lead to condensation, (d) map these questions back to the viral life cycle, and (e) design and test inhibitors/modulators of condensation as potential therapeutics. This experimental framework attempts to integrate virology, cell biology, and biochemistry approaches.
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Affiliation(s)
- Christine A Roden
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA;
| | - Amy S Gladfelter
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, USA;
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Regina Chua Avecilla A, Thomas J, Quiroz FG. Genetically-encoded phase separation sensors for intracellular probing of biomolecular condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.29.610365. [PMID: 39257779 PMCID: PMC11383673 DOI: 10.1101/2024.08.29.610365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Biomolecular condensates are dynamic membraneless compartments with enigmatic roles across intracellular phenomena. Intrinsically-disordered proteins (IDPs) often function as condensate scaffolds, fueled by their liquid-liquid phase separation (LLPS) dynamics. Intracellular probing of these condensates relies on live-cell imaging of IDP-scaffolds tagged with fluorescent proteins. Conformational heterogeneity in IDPs, however, renders them uniquely sensitive to molecular-level fusions, risking distortion of the native biophysical properties of IDP-scaffolds and their assemblies. Probing epidermal condensates in mouse skin, we recently introduced genetically encoded LLPS-sensors that circumvent the need for molecular-level tagging of skin IDPs. The concept of LLPS-sensors involves a shift in focus from subcellular tracking of IDP-scaffolds to higher-level observations that report on the assembly and liquid-dynamics of their condensates. Towards advancing the repertoire of intracellular LLPS-sensors, here we demonstrate biomolecular approaches for the evolution and tunability of epidermal LLPS-sensors and assess their impact in early and late stages of intracellular LLPS dynamics. Benchmarking against scaffold-bound fluorescent reporters, we found that tunable ultraweak scaffold-sensor interactions are key to the sensitive and innocuous probing of nascent and established biomolecular condensates. Our LLPS-sensitive tools pave the way for the high-fidelity intracellular probing of IDP-governed biomolecular condensates across biological systems.
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Affiliation(s)
- Alexa Regina Chua Avecilla
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
| | - Jeremy Thomas
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
| | - Felipe Garcia Quiroz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA
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6
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Stormo BM, McLaughlin GA, Jalihal AP, Frederick LK, Cole SJ, Seim I, Dietrich FS, Chilkoti A, Gladfelter AS. Intrinsically disordered sequences can tune fungal growth and the cell cycle for specific temperatures. Curr Biol 2024; 34:3722-3734.e7. [PMID: 39089255 PMCID: PMC11372857 DOI: 10.1016/j.cub.2024.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 05/16/2024] [Accepted: 07/02/2024] [Indexed: 08/03/2024]
Abstract
Temperature can impact every reaction essential to a cell. For organisms that cannot regulate their own temperature, adapting to temperatures that fluctuate unpredictably and on variable timescales is a major challenge. Extremes in the magnitude and frequency of temperature changes are increasing across the planet, raising questions as to how the biosphere will respond. To examine mechanisms of adaptation to temperature, we collected wild isolates from different climates of the fungus Ashbya gossypii, which has a compact genome of only ∼4,600 genes. We found control of the nuclear division cycle and polarized morphogenesis, both critical processes for fungal growth, were temperature sensitive and varied among the isolates. The phenotypes were associated with naturally varying sequences within the glutamine-rich region (QRR) IDR of an RNA-binding protein called Whi3. This protein regulates both nuclear division and polarized growth via its ability to form biomolecular condensates. In cells and in cell-free reconstitution assays, we found that temperature tunes the properties of Whi3-based condensates. Exchanging Whi3 sequences between isolates was sufficient to rescue temperature-sensitive phenotypes, and specifically, a heptad repeat sequence within the QRR confers temperature-sensitive behavior. Together, these data demonstrate that sequence variation in the size and composition of an IDR can promote cell adaptation to growth at specific temperature ranges. These data demonstrate the power of IDRs as tuning knobs for rapid adaptation to environmental fluctuations.
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Affiliation(s)
- Benjamin M Stormo
- Duke University, Department of Cell Biology, 308 Research Drive, Durham, NC 27705, USA
| | - Grace A McLaughlin
- Duke University, Department of Cell Biology, 308 Research Drive, Durham, NC 27705, USA; University of North Carolina-Chapel Hill, Department of Biology, 120 South Road, Chapel Hill, NC 27599, USA
| | - Ameya P Jalihal
- Duke University, Department of Cell Biology, 308 Research Drive, Durham, NC 27705, USA
| | - Logan K Frederick
- University of North Carolina-Chapel Hill, Department of Biology, 120 South Road, Chapel Hill, NC 27599, USA
| | - Sierra J Cole
- Duke University, Department of Cell Biology, 308 Research Drive, Durham, NC 27705, USA; University of North Carolina-Chapel Hill, Department of Biochemistry and Biophysics, 120 Mason Farm Road, Chapel Hill, NC 27599, USA
| | - Ian Seim
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Fred S Dietrich
- Duke University, Department of Molecular Genetics and Microbiology, 213 Research Drive, Durham, NC 27710, USA
| | - Ashutosh Chilkoti
- Duke University, Department of Biomedical Engineering, 101 Science Drive, Durham, NC 27705, USA
| | - Amy S Gladfelter
- Duke University, Department of Cell Biology, 308 Research Drive, Durham, NC 27705, USA.
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7
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Rana U, Xu K, Narayanan A, Walls MT, Panagiotopoulos AZ, Avalos JL, Brangwynne CP. Asymmetric oligomerization state and sequence patterning can tune multiphase condensate miscibility. Nat Chem 2024; 16:1073-1082. [PMID: 38383656 PMCID: PMC11230906 DOI: 10.1038/s41557-024-01456-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 01/19/2024] [Indexed: 02/23/2024]
Abstract
Endogenous biomolecular condensates, composed of a multitude of proteins and RNAs, can organize into multiphasic structures with compositionally distinct phases. This multiphasic organization is generally understood to be critical for facilitating their proper biological function. However, the biophysical principles driving multiphase formation are not completely understood. Here we use in vivo condensate reconstitution experiments and coarse-grained molecular simulations to investigate how oligomerization and sequence interactions modulate multiphase organization in biomolecular condensates. We demonstrate that increasing the oligomerization state of an intrinsically disordered protein results in enhanced immiscibility and multiphase formation. Interestingly, we find that oligomerization tunes the miscibility of intrinsically disordered proteins in an asymmetric manner, with the effect being more pronounced when the intrinsically disordered protein, exhibiting stronger homotypic interactions, is oligomerized. Our findings suggest that oligomerization is a flexible biophysical mechanism that cells can exploit to tune the internal organization of biomolecular condensates and their associated biological functions.
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Affiliation(s)
- Ushnish Rana
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Ke Xu
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Amal Narayanan
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
- Howard Hughes Medical Institute, Princeton University, Princeton, NJ, USA
| | - Mackenzie T Walls
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | | | - José L Avalos
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA.
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ, USA.
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ, USA.
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA.
- Howard Hughes Medical Institute, Princeton University, Princeton, NJ, USA.
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ, USA.
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Boyer NP, Sharma R, Wiesner T, Delamare A, Pelletier F, Leterrier C, Roy S. Spectrin condensates provide a nidus for assembling the periodic axonal structure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.05.597638. [PMID: 38895400 PMCID: PMC11185721 DOI: 10.1101/2024.06.05.597638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Coordinated assembly of individual components into higher-order structures is a defining theme in biology, but underlying principles are not well-understood. In neurons, α/β spectrins, adducin, and actinfilaments assemble into a lattice wrapping underneath the axonal plasma membrane, but mechanistic events leading to this periodic axonal structure (PAS) are unclear. Visualizing PAS components in axons as they develop, we found focal patches in distal axons containing spectrins and adducin (but sparse actin filaments) with biophysical properties reminiscent of biomolecular condensation. Overexpressing spectrin-repeats - constituents of α/β-spectrins - in heterologous cells triggered condensate formation, and preventing association of βII-spectrin with actin-filaments/membranes also facilitated condensation. Finally, overexpressing condensate-triggering spectrin repeats in neurons before PAS establishment disrupted the lattice, presumably by competing with innate assembly, supporting a functional role for biomolecular condensation. We propose a condensation-assembly model where PAS components form focal phase-separated condensates that eventually unfurl into a stable lattice-structure by associating with subplasmalemmal actin. By providing local 'depots' of assembly parts, biomolecular condensation may play a wider role in the construction of intricate cytoskeletal structures.
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9
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Iwahara J. Transient helices with functional roles. Biophys J 2024; 123:1314-1315. [PMID: 38308437 PMCID: PMC11163282 DOI: 10.1016/j.bpj.2024.01.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 01/30/2024] [Accepted: 01/30/2024] [Indexed: 02/04/2024] Open
Affiliation(s)
- Junji Iwahara
- Department of Biochemistry & Molecular Biology, Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas.
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10
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Wang SH, Zheng T, Fawzi NL. Structure and interactions of prion-like domains in transcription factor Efg1 phase separation. Biophys J 2024; 123:1481-1493. [PMID: 38297837 PMCID: PMC11163291 DOI: 10.1016/j.bpj.2024.01.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/08/2024] [Accepted: 01/25/2024] [Indexed: 02/02/2024] Open
Abstract
Candida albicans, a prominent member of the human microbiome, can make an opportunistic switch from commensal coexistence to pathogenicity accompanied by an epigenetic shift between the white and opaque cell states. This transcriptional switch is under precise regulation by a set of transcription factors (TFs), with Enhanced Filamentous Growth Protein 1 (Efg1) playing a central role. Previous research has emphasized the importance of Efg1's prion-like domain (PrLD) and the protein's ability to undergo phase separation for the white-to-opaque transition of C. albicans. However, the underlying molecular mechanisms of Efg1 phase separation have remained underexplored. In this study, we delved into the biophysical basis of Efg1 phase separation, revealing the significant contribution of both N-terminal (N) and C-terminal (C) PrLDs. Through NMR structural analysis, we found that Efg1 N-PrLD and C-PrLD are mostly disordered but have prominent partial α-helical secondary structures in both domains. NMR titration experiments suggest that the partially helical structures in N-PrLD act as hubs for self-interaction as well as Efg1 interaction with RNA. Using condensed-phase NMR spectroscopy, we uncovered diverse amino acid interactions underlying Efg1 phase separation. Particularly, we highlight the indispensable role of tyrosine residues within the transient α-helical structures of PrLDs particularly in the N-PrLD compared to the C-PrLD in stabilizing phase separation. Our study provides evidence that the transient α-helical structure is present in the phase-separated state and highlights the particular importance of aromatic residues within these structures for phase separation. Together, these results enhance the understanding of C. albicans transcription factor interactions that lead to virulence and provide a crucial foundation for potential antifungal therapies targeting the transcriptional switch.
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Affiliation(s)
- Szu-Huan Wang
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island
| | - Tongyin Zheng
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island.
| | - Nicolas L Fawzi
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island.
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11
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Hegde O, Li T, Sharma A, Borja M, Jacobs WM, Rogers WB. Competition between Self-Assembly and Phase Separation Governs High-Temperature Condensation of a DNA Liquid. PHYSICAL REVIEW LETTERS 2024; 132:208401. [PMID: 38829088 DOI: 10.1103/physrevlett.132.208401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/21/2024] [Accepted: 04/19/2024] [Indexed: 06/05/2024]
Abstract
In many biopolymer solutions, attractive interactions that stabilize finite-sized clusters at low concentrations also promote phase separation at high concentrations. Here we study a model biopolymer system that exhibits the opposite behavior, whereby self-assembly of DNA oligonucleotides into finite-sized, stoichiometric clusters tends to inhibit phase separation. We first use microfluidics-based experiments to map a novel phase transition in which the oligonucleotides condense as the temperature increases at high concentrations of divalent cations. We then show that a theoretical model of competition between self-assembly and phase separation quantitatively predicts changes in experimental phase diagrams arising from DNA sequence perturbations. Our results point to a general mechanism by which self-assembly shapes phase boundaries in complex biopolymer solutions.
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Affiliation(s)
- Omkar Hegde
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Tianhao Li
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Anjali Sharma
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Marco Borja
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - William M Jacobs
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - W Benjamin Rogers
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
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12
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Liang Q, Peng N, Xie Y, Kumar N, Gao W, Miao Y. MolPhase, an advanced prediction algorithm for protein phase separation. EMBO J 2024; 43:1898-1918. [PMID: 38565952 PMCID: PMC11065880 DOI: 10.1038/s44318-024-00090-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 02/27/2024] [Accepted: 03/14/2024] [Indexed: 04/04/2024] Open
Abstract
We introduce MolPhase, an advanced algorithm for predicting protein phase separation (PS) behavior that improves accuracy and reliability by utilizing diverse physicochemical features and extensive experimental datasets. MolPhase applies a user-friendly interface to compare distinct biophysical features side-by-side along protein sequences. By additional comparison with structural predictions, MolPhase enables efficient predictions of new phase-separating proteins and guides hypothesis generation and experimental design. Key contributing factors underlying MolPhase include electrostatic pi-interactions, disorder, and prion-like domains. As an example, MolPhase finds that phytobacterial type III effectors (T3Es) are highly prone to homotypic PS, which was experimentally validated in vitro biochemically and in vivo in plants, mimicking their injection and accumulation in the host during microbial infection. The physicochemical characteristics of T3Es dictate their patterns of association for multivalent interactions, influencing the material properties of phase-separating droplets based on the surrounding microenvironment in vivo or in vitro. Robust integration of MolPhase's effective prediction and experimental validation exhibit the potential to evaluate and explore how biomolecule PS functions in biological systems.
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Affiliation(s)
- Qiyu Liang
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Nana Peng
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Yi Xie
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Nivedita Kumar
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore
| | - Weibo Gao
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore
| | - Yansong Miao
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore, Singapore.
- Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 636921, Singapore, Singapore.
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13
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Gil-Garcia M, Benítez-Mateos AI, Papp M, Stoffel F, Morelli C, Normak K, Makasewicz K, Faltova L, Paradisi F, Arosio P. Local environment in biomolecular condensates modulates enzymatic activity across length scales. Nat Commun 2024; 15:3322. [PMID: 38637545 PMCID: PMC11026464 DOI: 10.1038/s41467-024-47435-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 03/28/2024] [Indexed: 04/20/2024] Open
Abstract
The mechanisms that underlie the regulation of enzymatic reactions by biomolecular condensates and how they scale with compartment size remain poorly understood. Here we use intrinsically disordered domains as building blocks to generate programmable enzymatic condensates of NADH-oxidase (NOX) with different sizes spanning from nanometers to microns. These disordered domains, derived from three distinct RNA-binding proteins, each possessing different net charge, result in the formation of condensates characterized by a comparable high local concentration of the enzyme yet within distinct environments. We show that only condensates with the highest recruitment of substrate and cofactor exhibit an increase in enzymatic activity. Notably, we observe an enhancement in enzymatic rate across a wide range of condensate sizes, from nanometers to microns, indicating that emergent properties of condensates can arise within assemblies as small as nanometers. Furthermore, we show a larger rate enhancement in smaller condensates. Our findings demonstrate the ability of condensates to modulate enzymatic reactions by creating distinct effective solvent environments compared to the surrounding solution, with implications for the design of protein-based heterogeneous biocatalysts.
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Affiliation(s)
- Marcos Gil-Garcia
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Ana I Benítez-Mateos
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Marcell Papp
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Florence Stoffel
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Chiara Morelli
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Karl Normak
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Katarzyna Makasewicz
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Lenka Faltova
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Francesca Paradisi
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Paolo Arosio
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland.
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14
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Ramirez DA, Hough LE, Shirts MR. Coiled-coil domains are sufficient to drive liquid-liquid phase separation in protein models. Biophys J 2024; 123:703-717. [PMID: 38356260 PMCID: PMC10995412 DOI: 10.1016/j.bpj.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 12/09/2023] [Accepted: 02/09/2024] [Indexed: 02/16/2024] Open
Abstract
Liquid-liquid phase separation (LLPS) is thought to be a main driving force in the formation of membraneless organelles. Examples of such organelles include the centrosome, central spindle, and stress granules. Recently, it has been shown that coiled-coil (CC) proteins, such as the centrosomal proteins pericentrin, spd-5, and centrosomin, might be capable of LLPS. CC domains have physical features that could make them the drivers of LLPS, but it is unknown if they play a direct role in the process. We developed a coarse-grained simulation framework for investigating the LLPS propensity of CC proteins, in which interactions that support LLPS arise solely from CC domains. We show, using this framework, that the physical features of CC domains are sufficient to drive LLPS of proteins. The framework is specifically designed to investigate how the number of CC domains, as well as the multimerization state of CC domains, can affect LLPS. We show that small model proteins with as few as two CC domains can phase separate. Increasing the number of CC domains up to four per protein can somewhat increase LLPS propensity. We demonstrate that trimer-forming and tetramer-forming CC domains have a dramatically higher LLPS propensity than dimer-forming coils, which shows that multimerization state has a greater effect on LLPS than the number of CC domains per protein. These data support the hypothesis of CC domains as drivers of protein LLPS, and have implications in future studies to identify the LLPS-driving regions of centrosomal and central spindle proteins.
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Affiliation(s)
- Dominique A Ramirez
- Department of Biochemistry, University of Colorado Boulder, Boulder, Colorado
| | - Loren E Hough
- Department of Physics and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado
| | - Michael R Shirts
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado.
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15
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Li S, Zhang Y, Chen J. Backbone interactions and secondary structures in phase separation of disordered proteins. Biochem Soc Trans 2024; 52:319-329. [PMID: 38348795 DOI: 10.1042/bst20230618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/29/2024]
Abstract
Intrinsically disordered proteins (IDPs) are one of the major drivers behind the formation and characteristics of biomolecular condensates. Due to their inherent flexibility, the backbones of IDPs are significantly exposed, rendering them highly influential and susceptible to biomolecular phase separation. In densely packed condensates, exposed backbones have a heightened capacity to interact with neighboring protein chains, which might lead to strong coupling between the secondary structures and phase separation and further modulate the subsequent transitions of the condensates, such as aging and fibrillization. In this mini-review, we provide an overview of backbone-mediated interactions and secondary structures within biomolecular condensates to underscore the importance of protein backbones in phase separation. We further focus on recent advances in experimental techniques and molecular dynamics simulation methods for probing and exploring the roles of backbone interactions and secondary structures in biomolecular phase separation involving IDPs.
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Affiliation(s)
- Shanlong Li
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Yumeng Zhang
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, U.S.A
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16
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Cheng L, De Leon-Rodriguez LM, Gilbert EP, Loo T, Petters L, Yang Z. Self-assembly and hydrogelation of a potential bioactive peptide derived from quinoa proteins. Int J Biol Macromol 2024; 259:129296. [PMID: 38199549 DOI: 10.1016/j.ijbiomac.2024.129296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/25/2023] [Accepted: 01/05/2024] [Indexed: 01/12/2024]
Abstract
In this work the identification of peptides derived from quinoa proteins which could potentially self-assemble, and form hydrogels was carried out with TANGO, a statistical mechanical based algorithm that predicts β-aggregate propensity of peptides. Peptides with the highest aggregate propensity were subjected to gelling screening experiments from which the most promising bioactive peptide with sequence KIVLDSDDPLFGGF was selected. The self-assembling and hydrogelation properties of the C-terminal amidated peptide (KIVLDSDDPLFGGF-NH2) were studied. The effect of concentration, pH, and temperature on the secondary structure of the peptide were probed by circular dichroism (CD), while its nanostructure was studied by transmission electron microscopy (TEM) and small-angle neutron scattering (SANS). Results revealed the existence of random coil, α-helix, twisted β-sheet, and well-defined β-sheet secondary structures, with a range of nanostructures including elongated fibrils and bundles, whose proportion was dependant on the peptide concentration, pH, or temperature. The self-assembly of the peptide is demonstrated to follow established models of amyloid formation, which describe the unfolded peptide transiting from an α-helix-containing intermediate into β-sheet-rich protofibrils. The self-assembly is promoted at high concentrations, elevated temperatures, and pH values close to the peptide isoelectric point, and presumably mediated by hydrogen bond, hydrophobic and electrostatic interactions, and π-π interactions (from the F residue). At 15 mg/mL and pH 3.5, the peptide self-assembled and formed a self-supporting hydrogel exhibiting viscoelastic behaviour with G' (1 Hz) ~2300 Pa as determined by oscillatory rheology measurements. The study describes a straightforward method to monitor the self-assembly of plant protein derived peptides; further studies are needed to demonstrate the potential application of the formed hydrogels in food and biomedicine.
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Affiliation(s)
- Lirong Cheng
- Riddet Institute, Massey University, Palmerston North 4442, New Zealand
| | | | - Elliot Paul Gilbert
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee, NSW, Australia; Centre for Nutrition and Food Sciences, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Trevor Loo
- BioProtection Aotearoa, School of Natural Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Ludwig Petters
- School of Natural Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Zhi Yang
- School of Food and Advanced Technology, Massey University, Auckland 0632, New Zealand.
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17
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Chattaraj A, Baltaci Z, Mayer BJ, Loew LM, Ditlev JA. Measurement of solubility product in a model condensate reveals the interplay of small oligomerization and self-association. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576869. [PMID: 38328089 PMCID: PMC10849621 DOI: 10.1101/2024.01.23.576869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Cellular condensates often consist of 10s to 100s of distinct interacting molecular species. Because of the complexity of these interactions, predicting the point at which they will undergo phase separation into discrete compartments is daunting. Using experiments and computation, we therefore studied a simple model system consisting of 2 proteins, polySH3 and polyPRM, designed for pentavalent heterotypic binding. We tested whether the peak solubility product, the product of dilute phase monomer concentrations, is a predictive parameter for the onset of phase separation. Titrating up equal total concentrations of each component showed that the maximum solubility product does approximately coincide with the threshold for phase separation in both the experiments and models. However, we found that measurements of dilute phase concentration include contributions from small oligomers, not just monomers; therefore, a quantitative comparison of the experiments and models required inclusion of small oligomers in the model analysis. We also examined full phase diagrams where the model results were almost symmetric along the diagonal, but the experimental results were highly asymmetric. This led us to perform dynamic light scattering experiments, where we discovered a weak homotypic interaction for polyPRM; when this was added to the computational model, it was able to recapitulate the experimentally observed asymmetry. Thus, comparing experiments to simulation reveals that the solubility product can be predictive of phase separation, even if small oligomers and low affinity homotypic interactions preclude experimental measurement of monomer concentration.
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Affiliation(s)
- Aniruddha Chattaraj
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut, United States of America
| | - Zeynep Baltaci
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Bruce J. Mayer
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut, United States of America
- Genetics and Genome Sciences, University of Connecticut School of Medicine, Farmington, Connecticut, United States of America
| | - Leslie M. Loew
- R. D. Berlin Center for Cell Analysis and Modeling, University of Connecticut School of Medicine, Farmington, Connecticut, United States of America
| | - Jonathon A. Ditlev
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
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18
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Zhang Y, Li S, Gong X, Chen J. Toward Accurate Simulation of Coupling between Protein Secondary Structure and Phase Separation. J Am Chem Soc 2024; 146:342-357. [PMID: 38112495 PMCID: PMC10842759 DOI: 10.1021/jacs.3c09195] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Intrinsically disordered proteins (IDPs) frequently mediate phase separation that underlies the formation of a biomolecular condensate. Together with theory and experiment, efficient coarse-grained (CG) simulations have been instrumental in understanding the sequence-specific phase separation of IDPs. However, the widely used Cα-only models are limited in capturing the peptide nature of IDPs, particularly backbone-mediated interactions and effects of secondary structures, in phase separation. Here, we describe a hybrid resolution (HyRes) protein model toward a more accurate description of the backbone and transient secondary structures in phase separation. With an atomistic backbone and coarse-grained side chains, HyRes can semiquantitatively capture the residue helical propensity and overall chain dimension of monomeric IDPs. Using GY-23 as a model system, we show that HyRes is efficient enough for the direct simulation of spontaneous phase separation and, at the same time, appears accurate enough to resolve the effects of single His to Lys mutations. HyRes simulations also successfully predict increased β-structure formation in the condensate, consistent with available experimental CD data. We further utilize HyRes to study the phase separation of TPD-43, where several disease-related mutants in the conserved region (CR) have been shown to affect residual helicities and modulate the phase separation propensity as measured by the saturation concentration. The simulations successfully recapitulate the effect of these mutants on the helicity and phase separation propensity of TDP-43 CR. Analyses reveal that the balance between backbone and side chain-mediated interactions, but not helicity itself, actually determines phase separation propensity. These results support that HyRes represents an effective protein model for molecular simulation of IDP phase separation and will help to elucidate the coupling between transient secondary structures and phase separation.
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Affiliation(s)
| | | | - Xiping Gong
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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19
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Moors TE, Milovanovic D. Defining a Lewy Body: Running Up the Hill of Shifting Definitions and Evolving Concepts. JOURNAL OF PARKINSON'S DISEASE 2024; 14:17-33. [PMID: 38189713 PMCID: PMC10836569 DOI: 10.3233/jpd-230183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/14/2023] [Indexed: 01/09/2024]
Abstract
Lewy bodies (LBs) are pathological hallmarks of Parkinson's disease and dementia with Lewy bodies, characterized by the accumulation of α-synuclein (αSyn) protein in the brain. While LBs were first described a century ago, their formation and morphogenesis mechanisms remain incompletely understood. Here, we present a historical overview of LB definitions and highlight the importance of semantic clarity and precise definitions when describing brain inclusions. Recent breakthroughs in imaging revealed shared features within LB subsets and the enrichment of membrane-bound organelles in these structures, challenging the conventional LB formation model. We discuss the involvement of emerging concepts of liquid-liquid phase separation, where biomolecules demix from a solution to form dense condensates, as a potential LB formation mechanism. Finally, we emphasize the need for the operational definitions of LBs based on morphological characteristics and detection protocols, particularly in studies investigating LB formation mechanisms. A better understanding of LB organization and ultrastructure can contribute to the development of targeted therapeutic strategies for synucleinopathies.
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Affiliation(s)
- Tim E. Moors
- Ann Romney Center for Neurologic Diseases, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
- Einstein Center for Neuroscience, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität Berlin, and Berlin Institute of Health, Berlin, Germany
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20
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Li T, Rogers WB, Jacobs WM. Interplay between self-assembly and phase separation in a polymer-complex model. Phys Rev E 2023; 108:064501. [PMID: 38243474 DOI: 10.1103/physreve.108.064501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 11/14/2023] [Indexed: 01/21/2024]
Abstract
We present a theoretical model for predicting the phase behavior of polymer solutions in which phase separation competes with oligomerization. Specifically, we consider scenarios in which the assembly of polymer chains into stoichiometric complexes prevents the chains from phase-separating via attractive polymer-polymer interactions. Combining statistical associating fluid theory with a two-state description of self-assembly, we find that this model exhibits rich phase behavior, including reentrance, and we show how system-specific phase diagrams can be derived graphically. Importantly, we discuss why these phase diagrams can resemble-and yet are qualitatively distinct from-phase diagrams of polymer solutions with lower critical solution temperatures.
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Affiliation(s)
- Tianhao Li
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - W Benjamin Rogers
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - William M Jacobs
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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21
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Stormo BM, McLaughlin GA, Frederick LK, Jalihal AP, Cole SJ, Seim I, Dietrich FS, Gladfelter AS. Biomolecular condensates in fungi are tuned to function at specific temperatures. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.27.568884. [PMID: 38076832 PMCID: PMC10705276 DOI: 10.1101/2023.11.27.568884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2023]
Abstract
Temperature can impact every reaction and molecular interaction essential to a cell. For organisms that cannot regulate their own temperature, a major challenge is how to adapt to temperatures that fluctuate unpredictability and on variable timescales. Biomolecular condensation offers a possible mechanism for encoding temperature-responsiveness and robustness into cell biochemistry and organization. To explore this idea, we examined temperature adaptation in a filamentous-growing fungus called Ashbya gossypii that engages biomolecular condensates containing the RNA-binding protein Whi3 to regulate mitosis and morphogenesis. We collected wild isolates of Ashbya that originate in different climates and found that mitotic asynchrony and polarized growth, which are known to be controlled by the condensation of Whi3, are temperature sensitive. Sequence analysis in the wild strains revealed changes to specific domains within Whi3 known to be important in condensate formation. Using an in vitro condensate reconstitution assay we found that temperature impacts the relative abundance of protein to RNA within condensates and that this directly impacts the material properties of the droplets. Finally, we found that exchanging Whi3 genes between warm and cold isolates was sufficient to rescue some, but not all, condensate-related phenotypes. Together these data demonstrate that material properties of Whi3 condensates are temperature sensitive, that these properties are important for function, and that sequence optimizes properties for a given climate.
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Affiliation(s)
| | - Grace A. McLaughlin
- Duke University, Department of Cell Biology, Durham, NC
- University of North Carolina, Chapel Hill, Department of Biology
| | | | | | - Sierra J Cole
- Duke University, Department of Cell Biology, Durham, NC
- University of North Carolina, Chapel Hill, Department of Biochemistry and Biophysics
| | - Ian Seim
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Fred S. Dietrich
- Duke University, Department of Molecular Genetics and Microbiology, Durham, NC
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22
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Lin AZ, Ruff KM, Dar F, Jalihal A, King MR, Lalmansingh JM, Posey AE, Erkamp NA, Seim I, Gladfelter AS, Pappu RV. Dynamical control enables the formation of demixed biomolecular condensates. Nat Commun 2023; 14:7678. [PMID: 37996438 PMCID: PMC10667521 DOI: 10.1038/s41467-023-43489-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 11/10/2023] [Indexed: 11/25/2023] Open
Abstract
Cellular matter can be organized into compositionally distinct biomolecular condensates. For example, in Ashbya gossypii, the RNA-binding protein Whi3 forms distinct condensates with different RNA molecules. Using criteria derived from a physical framework for explaining how compositionally distinct condensates can form spontaneously via thermodynamic considerations, we find that condensates in vitro form mainly via heterotypic interactions in binary mixtures of Whi3 and RNA. However, within these condensates, RNA molecules become dynamically arrested. As a result, in ternary systems, simultaneous additions of Whi3 and pairs of distinct RNA molecules lead to well-mixed condensates, whereas delayed addition of an RNA component results in compositional distinctness. Therefore, compositional identities of condensates can be achieved via dynamical control, being driven, at least partially, by the dynamical arrest of RNA molecules. Finally, we show that synchronizing the production of different RNAs leads to more well-mixed, as opposed to compositionally distinct condensates in vivo.
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Affiliation(s)
- Andrew Z Lin
- Division of Biology and Biomedical Sciences, Plant and Microbial Biosciences, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Kiersten M Ruff
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Furqan Dar
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Ameya Jalihal
- Department of Cell Biology, Duke University, Durham, NC, 27708, USA
| | - Matthew R King
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Jared M Lalmansingh
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Ammon E Posey
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Nadia A Erkamp
- Department of Biomedical Engineering and Center for Biomolecular Condensates, James F. McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Yusuf Hamied Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Ian Seim
- Department of Cell Biology, Duke University, Durham, NC, 27708, USA
| | - Amy S Gladfelter
- Department of Cell Biology, Duke University, Durham, NC, 27708, USA.
| | - Rohit V Pappu
- Division of Biology and Biomedical Sciences, Plant and Microbial Biosciences, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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23
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Wang SH, Zheng T, Fawzi NL. Structure and position-specific interactions of prion-like domains in transcription factor Efg1 phase separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.566450. [PMID: 37986834 PMCID: PMC10659382 DOI: 10.1101/2023.11.09.566450] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Candida albicans, a prominent member of the human microbiome, can make an opportunistic switch from commensal coexistence to pathogenicity accompanied by an epigenetic shift between the white and opaque cell states. This transcriptional switch is under precise regulation by a set of transcription factors (TFs), with Enhanced Filamentous Growth Protein 1 (Efg1) playing a central role. Previous research has emphasized the importance of Egf1's prion-like domain (PrLD) and the protein's ability to undergo phase separation for the white-to-opaque transition of C. albicans. However, the underlying molecular mechanisms of Efg1 phase separation have remained underexplored. In this study, we delved into the biophysical basis of Efg1 phase separation, revealing the significant contribution of both N-terminal (N) and C-terminal (C) PrLDs. Through NMR structural analysis, we found that Efg1 N-PrLD and C-PrLD are mostly disordered though have prominent partial α-helical secondary structures in both domains. NMR titration experiments suggest that the partially helical structures in N-PrLD act as hubs for self-interaction as well as Efg1 interaction with RNA. Using condensed-phase NMR spectroscopy, we uncovered diverse amino acid interactions underlying Efg1 phase separation. Particularly, we highlight the indispensable role of tyrosine residues within the transient α-helical structures of PrLDs particularly in the N-PrLD compared to the C-PrLD in stabilizing phase separation. Our study provides evidence that the transient α-helical structure is present in the phase separated state and highlights the particular importance of aromatic residues within these structures for phase separation. Together, these results enhance the understanding of C. albicans TF interactions that lead to virulence and provide a crucial foundation for potential antifungal therapies targeting the transcriptional switch.
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Affiliation(s)
- Szu-Huan Wang
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence Rhode Island, 02912, USA
- These authors contributed equally to this work
| | - Tongyin Zheng
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence Rhode Island, 02912, USA
- These authors contributed equally to this work
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence Rhode Island, 02912, USA
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24
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Sneideris T, Erkamp NA, Ausserwöger H, Saar KL, Welsh TJ, Qian D, Katsuya-Gaviria K, Johncock MLLY, Krainer G, Borodavka A, Knowles TPJ. Targeting nucleic acid phase transitions as a mechanism of action for antimicrobial peptides. Nat Commun 2023; 14:7170. [PMID: 37935659 PMCID: PMC10630377 DOI: 10.1038/s41467-023-42374-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 10/10/2023] [Indexed: 11/09/2023] Open
Abstract
Antimicrobial peptides (AMPs), which combat bacterial infections by disrupting the bacterial cell membrane or interacting with intracellular targets, are naturally produced by a number of different organisms, and are increasingly also explored as therapeutics. However, the mechanisms by which AMPs act on intracellular targets are not well understood. Using machine learning-based sequence analysis, we identified a significant number of AMPs that have a strong tendency to form liquid-like condensates in the presence of nucleic acids through phase separation. We demonstrate that this phase separation propensity is linked to the effectiveness of the AMPs in inhibiting transcription and translation in vitro, as well as their ability to compact nucleic acids and form clusters with bacterial nucleic acids in bacterial cells. These results suggest that the AMP-driven compaction of nucleic acids and modulation of their phase transitions constitute a previously unrecognised mechanism by which AMPs exert their antibacterial effects. The development of antimicrobials that target nucleic acid phase transitions may become an attractive route to finding effective and long-lasting antibiotics.
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Affiliation(s)
- Tomas Sneideris
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Nadia A Erkamp
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Hannes Ausserwöger
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Kadi L Saar
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Timothy J Welsh
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Daoyuan Qian
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Kai Katsuya-Gaviria
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK
| | - Margaret L L Y Johncock
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Georg Krainer
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK.
| | - Tuomas P J Knowles
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK.
- Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Ave, Cambridge, UK.
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25
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Mekonnen G, Djaja N, Yuan X, Myong S. Advanced imaging techniques for studying protein phase separation in living cells and at single-molecule level. Curr Opin Chem Biol 2023; 76:102371. [PMID: 37523989 PMCID: PMC10528199 DOI: 10.1016/j.cbpa.2023.102371] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/04/2023] [Accepted: 06/24/2023] [Indexed: 08/02/2023]
Abstract
Protein-protein and protein-RNA interactions are essential for cell function and survival. These interactions facilitate the formation of ribonucleoprotein complexes and biomolecular condensates via phase separation. Such assembly is involved in transcription, splicing, translation and stress response. When dysregulated, proteins and RNA can undergo irreversible aggregation which can be cytotoxic and pathogenic. Despite technical advances in investigating biomolecular condensates, achieving the necessary spatiotemporal resolution to deduce the parameters that govern their assembly and behavior has been challenging. Many laboratories have applied advanced microscopy methods for imaging condensates. For example, single molecule imaging methods have enabled the detection of RNA-protein interaction, protein-protein interaction, protein conformational dynamics, and diffusional motion of molecules that report on the intrinsic molecular interactions underlying liquid-liquid phase separation. This review will outline advances in both microscopy and spectroscopy techniques which allow single molecule detection and imaging, and how these techniques can be used to probe unique aspects of biomolecular condensates.
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Affiliation(s)
- Gemechu Mekonnen
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Nathalie Djaja
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Xincheng Yuan
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Sua Myong
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA; Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA.
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26
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Gao G, Walter NG. Critical Assessment of Condensate Boundaries in Dual-Color Single Particle Tracking. J Phys Chem B 2023; 127:7694-7707. [PMID: 37669232 DOI: 10.1021/acs.jpcb.3c03776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Biomolecular condensates are membraneless cellular compartments generated by phase separation that regulate a broad variety of cellular functions by enriching some biomolecules while excluding others. Live-cell single particle tracking of individual fluorophore-labeled condensate components has provided insights into a condensate's mesoscopic organization and biological functions, such as revealing the recruitment, translation, and decay of RNAs within ribonucleoprotein (RNP) granules. Specifically, during dual-color tracking, one imaging channel provides a time series of individual biomolecule locations, while the other channel monitors the location of the condensate relative to these molecules. Therefore, an accurate assessment of a condensate's boundary is critical for combined live-cell single particle-condensate tracking. Despite its importance, a quantitative benchmarking and objective comparison of the various available boundary detection methods is missing due to the lack of an absolute ground truth for condensate images. Here, we use synthetic data of defined ground truth to generate noise-overlaid images of condensates with realistic phase separation parameters to benchmark the most commonly used methods for condensate boundary detection, including an emerging machine-learning method. We find that it is critical to carefully choose an optimal boundary detection method for a given dataset to obtain accurate measurements of single particle-condensate interactions. The criteria proposed in this study to guide the selection of an optimal boundary detection method can be broadly applied to imaging-based studies of condensates.
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Affiliation(s)
- Guoming Gao
- Biophysics Graduate Program, University of Michigan, Ann Arbor, Michigan 48109, United States
- Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nils G Walter
- Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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27
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Farag M, Borcherds WM, Bremer A, Mittag T, Pappu RV. Phase separation of protein mixtures is driven by the interplay of homotypic and heterotypic interactions. Nat Commun 2023; 14:5527. [PMID: 37684240 PMCID: PMC10491635 DOI: 10.1038/s41467-023-41274-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
Prion-like low-complexity domains (PLCDs) are involved in the formation and regulation of distinct biomolecular condensates that form via phase separation coupled to percolation. Intracellular condensates often encompass numerous distinct proteins with PLCDs. Here, we combine simulations and experiments to study mixtures of PLCDs from two RNA-binding proteins, hnRNPA1 and FUS. Using simulations and experiments, we find that 1:1 mixtures of A1-LCD and FUS-LCD undergo phase separation more readily than either of the PLCDs on their own due to complementary electrostatic interactions. Tie line analysis reveals that stoichiometric ratios of different components and their sequence-encoded interactions contribute jointly to the driving forces for condensate formation. Simulations also show that the spatial organization of PLCDs within condensates is governed by relative strengths of homotypic versus heterotypic interactions. We uncover rules for how interaction strengths and sequence lengths modulate conformational preferences of molecules at interfaces of condensates formed by mixtures of proteins.
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Affiliation(s)
- Mina Farag
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Wade M Borcherds
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Anne Bremer
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
| | - Rohit V Pappu
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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28
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Zhang Y, Li S, Gong X, Chen J. Accurate Simulation of Coupling between Protein Secondary Structure and Liquid-Liquid Phase Separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554378. [PMID: 37662293 PMCID: PMC10473686 DOI: 10.1101/2023.08.22.554378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Intrinsically disordered proteins (IDPs) frequently mediate liquid-liquid phase separation (LLPS) that underlies the formation of membraneless organelles. Together with theory and experiment, efficient coarse-grained (CG) simulations have been instrumental in understanding sequence-specific phase separation of IDPs. However, the widely-used Cα-only models are severely limited in capturing the peptide nature of IDPs, including backbone-mediated interactions and effects of secondary structures, in LLPS. Here, we describe a hybrid resolution (HyRes) protein model for accurate description of the backbone and transient secondary structures in LLPS. With an atomistic backbone and coarse-grained side chains, HyRes accurately predicts the residue helical propensity and chain dimension of monomeric IDPs. Using GY-23 as a model system, we show that HyRes is efficient enough for direct simulation of spontaneous phase separation, and at the same time accurate enough to resolve the effects of single mutations. HyRes simulations also successfully predict increased beta-sheet formation in the condensate, consistent with available experimental data. We further utilize HyRes to study the phase separation of TPD-43, where several disease-related mutants in the conserved region (CR) have been shown to affect residual helicities and modulate LLPS propensity. The simulations successfully recapitulate the effect of these mutants on the helicity and LLPS propensity of TDP-43 CR. Analyses reveal that the balance between backbone and sidechain-mediated interactions, but not helicity itself, actually determines LLPS propensity. We believe that the HyRes model represents an important advance in the molecular simulation of LLPS and will help elucidate the coupling between IDP transient secondary structures and phase separation.
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Affiliation(s)
| | | | - Xiping Gong
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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29
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Lan C, Kim J, Ulferts S, Aprile-Garcia F, Weyrauch S, Anandamurugan A, Grosse R, Sawarkar R, Reinhardt A, Hugel T. Quantitative real-time in-cell imaging reveals heterogeneous clusters of proteins prior to condensation. Nat Commun 2023; 14:4831. [PMID: 37582808 PMCID: PMC10427612 DOI: 10.1038/s41467-023-40540-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023] Open
Abstract
Our current understanding of biomolecular condensate formation is largely based on observing the final near-equilibrium condensate state. Despite expectations from classical nucleation theory, pre-critical protein clusters were recently shown to form under subsaturation conditions in vitro; if similar long-lived clusters comprising more than a few molecules are also present in cells, our understanding of the physical basis of biological phase separation may fundamentally change. Here, we combine fluorescence microscopy with photobleaching analysis to quantify the formation of clusters of NELF proteins in living, stressed cells. We categorise small and large clusters based on their dynamics and their response to p38 kinase inhibition. We find a broad distribution of pre-condensate cluster sizes and show that NELF protein cluster formation can be explained as non-classical nucleation with a surprisingly flat free-energy landscape for a wide range of sizes and an inhibition of condensation in unstressed cells.
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Affiliation(s)
- Chenyang Lan
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
- BIOSS and CIBSS Signalling Research Centres, University of Freiburg, Freiburg, Germany
- PicoQuant GmbH, Rudower Chaussee 29, 12489, Berlin, Germany
| | - Juhyeong Kim
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
| | - Svenja Ulferts
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | | | - Sophie Weyrauch
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany
- Faculty of Chemistry and Pharmacology, University of Freiburg, Freiburg, Germany
| | | | - Robert Grosse
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg, Germany
| | - Ritwick Sawarkar
- Medical Research Council (MRC), University of Cambridge, Cambridge, CB2 1QR, United Kingdom
| | - Aleks Reinhardt
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, United Kingdom.
| | - Thorsten Hugel
- Institute of Physical Chemistry, University of Freiburg, Freiburg, Germany.
- BIOSS and CIBSS Signalling Research Centres, University of Freiburg, Freiburg, Germany.
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30
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Abstract
Biomolecular condensates are reversible compartments that form through a process called phase separation. Post-translational modifications like ADP-ribosylation can nucleate the formation of these condensates by accelerating the self-association of proteins. Poly(ADP-ribose) (PAR) chains are remarkably transient modifications with turnover rates on the order of minutes, yet they can be required for the formation of granules in response to oxidative stress, DNA damage, and other stimuli. Moreover, accumulation of PAR is linked with adverse phase transitions in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In this review, we provide a primer on how PAR is synthesized and regulated, the diverse structures and chemistries of ADP-ribosylation modifications, and protein-PAR interactions. We review substantial progress in recent efforts to determine the molecular mechanism of PAR-mediated phase separation, and we further delineate how inhibitors of PAR polymerases may be effective treatments for neurodegenerative pathologies. Finally, we highlight the need for rigorous biochemical interrogation of ADP-ribosylation in vivo and in vitro to clarify the exact pathway from PARylation to condensate formation.
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Affiliation(s)
- Kevin Rhine
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hana M Odeh
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - James Shorter
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - Sua Myong
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Physics Frontier Center (Center for the Physics of Living Cells), University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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31
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Abstract
Multivalent proteins and nucleic acids, collectively referred to as multivalent associative biomacromolecules, provide the driving forces for the formation and compositional regulation of biomolecular condensates. Here, we review the key concepts of phase transitions of aqueous solutions of associative biomacromolecules, specifically proteins that include folded domains and intrinsically disordered regions. The phase transitions of these systems come under the rubric of coupled associative and segregative transitions. The concepts underlying these processes are presented, and their relevance to biomolecular condensates is discussed.
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Affiliation(s)
- Rohit V. Pappu
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Samuel R. Cohen
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO 63130, USA
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Furqan Dar
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Mina Farag
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Mrityunjoy Kar
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
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32
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Ramirez DA, Hough LE, Shirts MR. Coiled-coil domains are sufficient to drive liquid-liquid phase separation of proteins in molecular models. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543124. [PMID: 37398035 PMCID: PMC10312653 DOI: 10.1101/2023.05.31.543124] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Liquid-liquid phase separation (LLPS) is thought to be a main driving force in the formation of membraneless organelles. Examples of such organelles include the centrosome, central spindle, and stress granules. Recently, it has been shown that coiled-coil (CC) proteins, such as the centrosomal proteins pericentrin, spd-5, and centrosomin, might be capable of LLPS. CC domains have physical features that could make them the drivers of LLPS, but it is unknown if they play a direct role in the process. We developed a coarse-grained simulation framework for investigating the LLPS propensity of CC proteins, in which interactions which support LLPS arise solely from CC domains. We show, using this framework, that the physical features of CC domains are sufficient to drive LLPS of proteins. The framework is specifically designed to investigate how the number of CC domains, as well as multimerization state of CC domains, can affect LLPS. We show that small model proteins with as few as two CC domains can phase separate. Increasing the number of CC domains up to four per protein can somewhat increase LLPS propensity. We demonstrate that trimer-forming and tetramer-forming CC domains have a dramatically higher LLPS propensity than dimer-forming coils, which shows that multimerization state has a greater effect on LLPS than the number of CC domains per protein. These data support the hypothesis of CC domains as drivers of protein LLPS, and has implications in future studies to identify the LLPS-driving regions of centrosomal and central spindle proteins.
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Affiliation(s)
| | - Loren E. Hough
- Department of Physics and BioFrontiers Institute, University of Colorado Boulder, Boulder CO, 80309
| | - Michael R. Shirts
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder CO, 80309
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33
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Polyansky AA, Gallego LD, Efremov RG, Köhler A, Zagrovic B. Protein compactness and interaction valency define the architecture of a biomolecular condensate across scales. eLife 2023; 12:e80038. [PMID: 37470705 PMCID: PMC10406433 DOI: 10.7554/elife.80038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/18/2023] [Indexed: 07/21/2023] Open
Abstract
Non-membrane-bound biomolecular condensates have been proposed to represent an important mode of subcellular organization in diverse biological settings. However, the fundamental principles governing the spatial organization and dynamics of condensates at the atomistic level remain unclear. The Saccharomyces cerevisiae Lge1 protein is required for histone H2B ubiquitination and its N-terminal intrinsically disordered fragment (Lge11-80) undergoes robust phase separation. This study connects single- and multi-chain all-atom molecular dynamics simulations of Lge11-80 with the in vitro behavior of Lge11-80 condensates. Analysis of modeled protein-protein interactions elucidates the key determinants of Lge11-80 condensate formation and links configurational entropy, valency, and compactness of proteins inside the condensates. A newly derived analytical formalism, related to colloid fractal cluster formation, describes condensate architecture across length scales as a function of protein valency and compactness. In particular, the formalism provides an atomistically resolved model of Lge11-80 condensates on the scale of hundreds of nanometers starting from individual protein conformers captured in simulations. The simulation-derived fractal dimensions of condensates of Lge11-80 and its mutants agree with their in vitro morphologies. The presented framework enables a multiscale description of biomolecular condensates and embeds their study in a wider context of colloid self-organization.
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Affiliation(s)
- Anton A Polyansky
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational BiologyViennaAustria
| | - Laura D Gallego
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- Medical University of Vienna, Center for Medical BiochemistryViennaAustria
| | - Roman G Efremov
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of SciencesMoscowRussian Federation
| | - Alwin Köhler
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- Medical University of Vienna, Center for Medical BiochemistryViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell BiologyViennaAustria
| | - Bojan Zagrovic
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational BiologyViennaAustria
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34
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Abstract
RNA granules are mesoscale assemblies that form in the absence of limiting membranes. RNA granules contain factors for RNA biogenesis and turnover and are often assumed to represent specialized compartments for RNA biochemistry. Recent evidence suggests that RNA granules assemble by phase separation of subsoluble ribonucleoprotein (RNP) complexes that partially demix from the cytoplasm or nucleoplasm. We explore the possibility that some RNA granules are nonessential condensation by-products that arise when RNP complexes exceed their solubility limit as a consequence of cellular activity, stress, or aging. We describe the use of evolutionary and mutational analyses and single-molecule techniques to distinguish functional RNA granules from "incidental condensates."
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Affiliation(s)
- Andrea Putnam
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University, Baltimore, Maryland 21205, USA
| | - Laura Thomas
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University, Baltimore, Maryland 21205, USA
| | - Geraldine Seydoux
- Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University, Baltimore, Maryland 21205, USA
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35
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Sil S, Keegan S, Ettefa F, Denes LT, Boeke JD, Holt LJ. Condensation of LINE-1 is critical for retrotransposition. eLife 2023; 12:e82991. [PMID: 37114770 PMCID: PMC10202459 DOI: 10.7554/elife.82991] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 04/27/2023] [Indexed: 04/29/2023] Open
Abstract
LINE-1 (L1) is the only autonomously active retrotransposon in the human genome, and accounts for 17% of the human genome. The L1 mRNA encodes two proteins, ORF1p and ORF2p, both essential for retrotransposition. ORF2p has reverse transcriptase and endonuclease activities, while ORF1p is a homotrimeric RNA-binding protein with poorly understood function. Here, we show that condensation of ORF1p is critical for L1 retrotransposition. Using a combination of biochemical reconstitution and live-cell imaging, we demonstrate that electrostatic interactions and trimer conformational dynamics together tune the properties of ORF1p assemblies to allow for efficient L1 ribonucleoprotein (RNP) complex formation in cells. Furthermore, we relate the dynamics of ORF1p assembly and RNP condensate material properties to the ability to complete the entire retrotransposon life-cycle. Mutations that prevented ORF1p condensation led to loss of retrotransposition activity, while orthogonal restoration of coiled-coil conformational flexibility rescued both condensation and retrotransposition. Based on these observations, we propose that dynamic ORF1p oligomerization on L1 RNA drives the formation of an L1 RNP condensate that is essential for retrotransposition.
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Affiliation(s)
- Srinjoy Sil
- Institute for Systems Genetics, New York University Langone Medical CenterNew YorkUnited States
| | - Sarah Keegan
- Institute for Systems Genetics, New York University Langone Medical CenterNew YorkUnited States
| | - Farida Ettefa
- Institute for Systems Genetics, New York University Langone Medical CenterNew YorkUnited States
| | - Lance T Denes
- Institute for Systems Genetics, New York University Langone Medical CenterNew YorkUnited States
| | - Jef D Boeke
- Institute for Systems Genetics, New York University Langone Medical CenterNew YorkUnited States
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Medical CenterNew YorkUnited States
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36
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Dai Y, You L, Chilkoti A. Engineering synthetic biomolecular condensates. NATURE REVIEWS BIOENGINEERING 2023; 1:1-15. [PMID: 37359769 PMCID: PMC10107566 DOI: 10.1038/s44222-023-00052-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 03/06/2023] [Indexed: 06/28/2023]
Abstract
The concept of phase-separation-mediated formation of biomolecular condensates provides a new framework to understand cellular organization and cooperativity-dependent cellular functions. With growing understanding of how biological systems drive phase separation and how cellular functions are encoded by biomolecular condensates, opportunities have emerged for cellular control through engineering of synthetic biomolecular condensates. In this Review, we discuss how to construct synthetic biomolecular condensates and how they can regulate cellular functions. We first describe the fundamental principles by which biomolecular components can drive phase separation. Next, we discuss the relationship between the properties of condensates and their cellular functions, which informs the design of components to create programmable synthetic condensates. Finally, we describe recent applications of synthetic biomolecular condensates for cellular control and discuss some of the design considerations and prospective applications.
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Affiliation(s)
- Yifan Dai
- Department of Biomedical Engineering, Duke University, Durham, NC USA
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, NC USA
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering, Duke University, Durham, NC USA
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37
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Farag M, Borcherds WM, Bremer A, Mittag T, Pappu RV. Phase Separation in Mixtures of Prion-Like Low Complexity Domains is Driven by the Interplay of Homotypic and Heterotypic Interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.15.532828. [PMID: 36993212 PMCID: PMC10055064 DOI: 10.1101/2023.03.15.532828] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Prion-like low-complexity domains (PLCDs) are involved in the formation and regulation of distinct biomolecular condensates that form via coupled associative and segregative phase transitions. We previously deciphered how evolutionarily conserved sequence features drive phase separation of PLCDs through homotypic interactions. However, condensates typically encompass a diverse mixture of proteins with PLCDs. Here, we combine simulations and experiments to study mixtures of PLCDs from two RNA binding proteins namely, hnRNPA1 and FUS. We find that 1:1 mixtures of the A1-LCD and FUS-LCD undergo phase separation more readily than either of the PLCDs on their own. The enhanced driving forces for phase separation of mixtures of A1-LCD and FUS-LCD arise partly from complementary electrostatic interactions between the two proteins. This complex coacervation-like mechanism adds to complementary interactions among aromatic residues. Further, tie line analysis shows that stoichiometric ratios of different components and their sequence-encoded interactions jointly contribute to the driving forces for condensate formation. These results highlight how expression levels might be tuned to regulate the driving forces for condensate formation in vivo . Simulations also show that the organization of PLCDs within condensates deviates from expectations based on random mixture models. Instead, spatial organization within condensates will reflect the relative strengths of homotypic versus heterotypic interactions. We also uncover rules for how interaction strengths and sequence lengths modulate conformational preferences of molecules at interfaces of condensates formed by mixtures of proteins. Overall, our findings emphasize the network-like organization of molecules within multicomponent condensates, and the distinctive, composition-specific conformational features of condensate interfaces. Significance Statement Biomolecular condensates are mixtures of different protein and nucleic acid molecules that organize biochemical reactions in cells. Much of what we know about how condensates form comes from studies of phase transitions of individual components of condensates. Here, we report results from studies of phase transitions of mixtures of archetypal protein domains that feature in distinct condensates. Our investigations, aided by a blend of computations and experiments, show that the phase transitions of mixtures are governed by a complex interplay of homotypic and heterotypic interactions. The results point to how expression levels of different protein components can be tuned in cells to modulate internal structures, compositions, and interfaces of condensates, thus affording distinct ways to control the functions of condensates.
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38
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Das D, Deniz AA. Topological Considerations in Biomolecular Condensation. Biomolecules 2023; 13:151. [PMID: 36671536 PMCID: PMC9855981 DOI: 10.3390/biom13010151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/07/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Biomolecular condensation and phase separation are increasingly understood to play crucial roles in cellular compartmentalization and spatiotemporal regulation of cell machinery implicated in function and pathology. A key aspect of current research is to gain insight into the underlying physical mechanisms of these processes. Accordingly, concepts of soft matter and polymer physics, the thermodynamics of mixing, and material science have been utilized for understanding condensation mechanisms of multivalent macromolecules resulting in viscoelastic mesoscopic supramolecular assemblies. Here, we focus on two topological concepts that have recently been providing key mechanistic understanding in the field. First, we will discuss how percolation provides a network-topology-related framework that offers an interesting paradigm to understand the complex networking of dense 'connected' condensate structures and, therefore, their phase behavior. Second, we will discuss the idea of entanglement as another topological concept that has deep roots in polymer physics and important implications for biomolecular condensates. We will first review some historical developments and fundamentals of these concepts, then we will discuss current advancements and recent examples. Our discussion ends with a few open questions and the challenges to address them, hinting at unveiling fresh possibilities for the modification of existing knowledge as well as the development of new concepts relevant to condensate science.
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Affiliation(s)
| | - Ashok A. Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA
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39
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He G, GrandPre T, Wilson H, Zhang Y, Jonikas MC, Wingreen NS, Wang Q. Phase-separating pyrenoid proteins form complexes in the dilute phase. Commun Biol 2023; 6:19. [PMID: 36611062 PMCID: PMC9825591 DOI: 10.1038/s42003-022-04373-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 12/13/2022] [Indexed: 01/09/2023] Open
Abstract
While most studies of biomolecular phase separation have focused on the condensed phase, relatively little is known about the dilute phase. Theory suggests that stable complexes form in the dilute phase of two-component phase-separating systems, impacting phase separation; however, these complexes have not been interrogated experimentally. We show that such complexes indeed exist, using an in vitro reconstitution system of a phase-separated organelle, the algal pyrenoid, consisting of purified proteins Rubisco and EPYC1. Applying fluorescence correlation spectroscopy (FCS) to measure diffusion coefficients, we found that complexes form in the dilute phase with or without condensates present. The majority of these complexes contain exactly one Rubisco molecule. Additionally, we developed a simple analytical model which recapitulates experimental findings and provides molecular insights into the dilute phase organization. Thus, our results demonstrate the existence of protein complexes in the dilute phase, which could play important roles in the stability, dynamics, and regulation of condensates.
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Affiliation(s)
- Guanhua He
- grid.16750.350000 0001 2097 5006Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA
| | - Trevor GrandPre
- grid.16750.350000 0001 2097 5006Department of Physics, Princeton University, Princeton, NJ 08544 USA ,grid.16750.350000 0001 2097 5006Center for the Physics of Biological Function, Princeton University, Princeton, NJ USA
| | - Hugh Wilson
- grid.16750.350000 0001 2097 5006Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 USA
| | - Yaojun Zhang
- grid.16750.350000 0001 2097 5006Center for the Physics of Biological Function, Princeton University, Princeton, NJ USA ,grid.21107.350000 0001 2171 9311Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Biophysics, Johns Hopkins University, Baltimore, MD USA
| | - Martin C. Jonikas
- grid.16750.350000 0001 2097 5006Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA ,grid.16750.350000 0001 2097 5006Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544 USA
| | - Ned S. Wingreen
- grid.16750.350000 0001 2097 5006Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA ,grid.16750.350000 0001 2097 5006Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 USA
| | - Quan Wang
- grid.16750.350000 0001 2097 5006Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 USA ,grid.419635.c0000 0001 2203 7304Present Address: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MA 20892 USA
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40
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Lin AZ, Ruff KM, Jalihal A, Dar F, King MR, Lalmansingh JM, Posey AE, Seim I, Gladfelter AS, Pappu RV. Dynamical control enables the formation of demixed biomolecular condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.04.522702. [PMID: 36711465 PMCID: PMC9881950 DOI: 10.1101/2023.01.04.522702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Macromolecular phase separation underlies the regulated formation and dissolution of biomolecular condensates. What is unclear is how condensates of distinct and shared macromolecular compositions form and coexist within cellular milieus. Here, we use theory and computation to establish thermodynamic criteria that must be satisfied to achieve compositionally distinct condensates. We applied these criteria to an archetypal ribonucleoprotein condensate and discovered that demixing into distinct protein-RNA condensates cannot be the result of purely thermodynamic considerations. Instead, demixed, compositionally distinct condensates arise due to asynchronies in timescales that emerge from differences in long-lived protein-RNA and RNA-RNA crosslinks. This type of dynamical control is also found to be active in live cells whereby asynchronous production of molecules is required for realizing demixed protein-RNA condensates. We find that interactions that exert dynamical control provide a versatile and generalizable way to influence the compositions of coexisting condensates in live cells.
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41
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Unravelling the microscopic characteristics of intrinsically disordered proteins upon liquid–liquid phase separation. Essays Biochem 2022; 66:891-900. [DOI: 10.1042/ebc20220148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/13/2022] [Accepted: 11/14/2022] [Indexed: 12/23/2022]
Abstract
Abstract
Biomolecular condensate formation via liquid–liquid phase separation (LLPS) has emerged as a ubiquitous mechanism underlying the spatiotemporal organization of biomolecules in the cell. These membraneless condensates form and disperse dynamically in response to environmental stimuli. Growing evidence indicates that the liquid-like condensates not only play functional physiological roles but are also implicated in a wide range of human diseases. As a major component of biomolecular condensates, intrinsically disordered proteins (IDPs) are intimately involved in the LLPS process. During the last decade, great efforts have been made on the macroscopic characterization of the physicochemical properties and biological functions of liquid condensates both in vitro and in the cellular context. However, characterization of the conformations and interactions at the molecular level within phase-separated condensates is still at an early stage. In the present review, we summarize recent biophysical studies investigating the intramolecular conformational changes of IDPs upon LLPS and the intermolecular clustering of proteins undergoing LLPS, with a particular focus on single-molecule fluorescence detection. We also discuss how these microscopic features are linked to the macroscopic phase transitions that are relevant to the physiological and pathological roles of the condensates.
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42
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Regulation of Polyhomeotic Condensates by Intrinsically Disordered Sequences That Affect Chromatin Binding. EPIGENOMES 2022; 6:epigenomes6040040. [PMID: 36412795 PMCID: PMC9680516 DOI: 10.3390/epigenomes6040040] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 10/30/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
The Polycomb group (PcG) complex PRC1 localizes in the nucleus in condensed structures called Polycomb bodies. The PRC1 subunit Polyhomeotic (Ph) contains an oligomerizing sterile alpha motif (SAM) that is implicated in both PcG body formation and chromatin organization in Drosophila and mammalian cells. A truncated version of Ph containing the SAM (mini-Ph) forms phase-separated condensates with DNA or chromatin in vitro, suggesting that PcG bodies may form through SAM-driven phase separation. In cells, Ph forms multiple small condensates, while mini-Ph typically forms a single large nuclear condensate. We therefore hypothesized that sequences outside of mini-Ph, which are predicted to be intrinsically disordered, are required for proper condensate formation. We identified three distinct low-complexity regions in Ph based on sequence composition. We systematically tested the role of each of these sequences in Ph condensates using live imaging of transfected Drosophila S2 cells. Each sequence uniquely affected Ph SAM-dependent condensate size, number, and morphology, but the most dramatic effects occurred when the central, glutamine-rich intrinsically disordered region (IDR) was removed, which resulted in large Ph condensates. Like mini-Ph condensates, condensates lacking the glutamine-rich IDR excluded chromatin. Chromatin fractionation experiments indicated that the removal of the glutamine-rich IDR reduced chromatin binding and that the removal of either of the other IDRs increased chromatin binding. Our data suggest that all three IDRs, and functional interactions among them, regulate Ph condensate size and number. Our results can be explained by a model in which tight chromatin binding by Ph IDRs antagonizes Ph SAM-driven phase separation. Our observations highlight the complexity of regulation of biological condensates housed in single proteins.
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43
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De Sancho D. Phase separation in amino acid mixtures is governed by composition. Biophys J 2022; 121:4119-4127. [PMID: 36181270 PMCID: PMC9675019 DOI: 10.1016/j.bpj.2022.09.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 07/19/2022] [Accepted: 09/26/2022] [Indexed: 11/02/2022] Open
Abstract
Macromolecular phase separation has recently come to immense prominence as it is central to the formation of membraneless organelles, leading to a new paradigm of cellular organization. This type of phase transition, often termed liquid-liquid phase separation (LLPS), is mediated by molecular interactions between biomolecules, including nucleic acids and both ordered and disordered proteins. In the latter case, the separation between protein-dense and -dilute phases is often interpreted using models adapted from polymer theory. Specifically, the "stickers and spacers" model proposes that the formation of condensate-spanning networks in protein solutions originates from the interplay between two classes of residues and that the main determinants for phase separation are multivalency and sequence patterning. The duality of roles of stickers (aromatics like Phe and Tyr) and spacers (Gly and polar residues) may apply more broadly in protein-like mixtures, and the presence of these two types of components alone may suffice for LLPS to take place. In order to explore this hypothesis, we use atomistic molecular dynamics simulations of capped amino acid residues as a minimal model system. We study the behavior of pure amino acids in water for three types of residues corresponding to the spacer and sticker categories and of their multicomponent mixtures. In agreement with previous observations, we find that the spacer-type amino acids fail to phase separate on their own, while the sticker is prone to aggregation. However, ternary amino acid mixtures involving both types of amino acids phase separate into two phases that retain intermediate degrees of compaction and greater fluidity than sticker-only condensates. Our results suggest that LLPS is an emergent property of amino acid mixtures determined by composition.
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Affiliation(s)
- David De Sancho
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, UPV/EHU & Donostia International Physics Center (DIPC), PK 1072, Donostia-San Sebastian, Euskadi, Spain.
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44
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Feric M, Sarfallah A, Dar F, Temiakov D, Pappu RV, Misteli T. Mesoscale structure-function relationships in mitochondrial transcriptional condensates. Proc Natl Acad Sci U S A 2022; 119:e2207303119. [PMID: 36191226 PMCID: PMC9565167 DOI: 10.1073/pnas.2207303119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 09/09/2022] [Indexed: 12/14/2022] Open
Abstract
In live cells, phase separation is thought to organize macromolecules into membraneless structures known as biomolecular condensates. Here, we reconstituted transcription in condensates from purified mitochondrial components using optimized in vitro reaction conditions to probe the structure-function relationships of biomolecular condensates. We find that the core components of the mt-transcription machinery form multiphasic, viscoelastic condensates in vitro. Strikingly, the rates of condensate-mediated transcription are substantially lower than in solution. The condensate-mediated decrease in transcriptional rates is associated with the formation of vesicle-like structures that are driven by the production and accumulation of RNA during transcription. The generation of RNA alters the global phase behavior and organization of transcription components within condensates. Coarse-grained simulations of mesoscale structures at equilibrium show that the components stably assemble into multiphasic condensates and that the vesicles formed in vitro are the result of dynamical arrest. Overall, our findings illustrate the complex phase behavior of transcribing, multicomponent condensates, and they highlight the intimate, bidirectional interplay of structure and function in transcriptional condensates.
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Affiliation(s)
- Marina Feric
- National Cancer Institute, NIH, Bethesda, MD 20892
- National Institute of General Medical Sciences, NIH, Bethesda, MD 20892
| | - Azadeh Sarfallah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Furqan Dar
- Department of Physics, Washington University in St. Louis, St. Louis, MO 63130
- Department of Biomedical Engineering, Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO 63130
| | - Dmitry Temiakov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Rohit V. Pappu
- Department of Biomedical Engineering, Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO 63130
| | - Tom Misteli
- National Cancer Institute, NIH, Bethesda, MD 20892
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45
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Wang T, Hu J, Li Y, Bi L, Guo L, Jia X, Zhang X, Li D, Hou X, Modesti M, Xi X, Liu C, Sun B. Bloom Syndrome Helicase Compresses Single‐Stranded DNA into Phase‐Separated Condensates. Angew Chem Int Ed Engl 2022; 61:e202209463. [DOI: 10.1002/anie.202209463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Teng Wang
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Jiaojiao Hu
- Interdisciplinary Research Center on Biology and Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 201210 China
| | - Yanan Li
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Lulu Bi
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Lijuan Guo
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Xinshuo Jia
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Xia Zhang
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
| | - Dan Li
- Bio-X Institutes Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders Ministry of Education Shanghai Jiao Tong University Shanghai 200030 China
| | - Xi‐Miao Hou
- College of Life Sciences Northwest A&F University Yangling Shaanxi 712100 China
| | - Mauro Modesti
- Cancer Research Center of Marseille CNRS UMR7258 Inserm U1068 Institut Paoli-Calmettes Aix-Marseille Université 13273 Marseille France
| | - Xu‐Guang Xi
- College of Life Sciences Northwest A&F University Yangling Shaanxi 712100 China
- Laboratoire de Biologie et Pharmacologie Appliquée (LBPA) CNRS UMR8113 ENS Pairs-Saclay Université Paris-Saclay 91190 Gif-sur-Yvette France
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 201210 China
| | - Bo Sun
- School of Life Science and Technology ShanghaiTech University Shanghai 201210 China
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46
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Ren CL, Shan Y, Zhang P, Ding HM, Ma YQ. Uncovering the molecular mechanism for dual effect of ATP on phase separation in FUS solution. SCIENCE ADVANCES 2022; 8:eabo7885. [PMID: 36103543 PMCID: PMC9473584 DOI: 10.1126/sciadv.abo7885] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 07/28/2022] [Indexed: 06/04/2023]
Abstract
Recent studies reported that adenosine triphosphate (ATP) could inhibit and enhance the phase separation in prion-like proteins. The molecular mechanism underlying such a puzzling phenomenon remains elusive. Here, taking the fused in sarcoma (FUS) solution as an example, we comprehensively reveal the underlying mechanism by which ATP regulates phase separation by combining the semiempirical quantum mechanical method, mean-field theory, and molecular simulation. At the microscopic level, ATP acts as a bivalent or trivalent binder; at the macroscopic level, the reentrant phase separation occurs in dilute FUS solutions, resulting from the ATP concentration-dependent binding ability under different conditions. The ATP concentration for dissolving the protein condensates is about 10 mM, agreeing with experimental results. Furthermore, from a dynamic point of view, the effect of ATP on phase separation is also nonmonotonic. This work provides a clear physical description of the microscopic interaction and macroscopic phase diagram of the ATP-modulated phase separation.
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Affiliation(s)
- Chun-Lai Ren
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yue Shan
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Pengfei Zhang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-Dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Hong-Ming Ding
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou 215006, China
| | - Yu-Qiang Ma
- National Laboratory of Solid State Microstructures and Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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47
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Wang T, Hu J, Li Y, Bi L, Guo L, Jia X, Zhang X, Li D, Hou XM, Modesti M, Xi XG, Liu C, SUN BO. Bloom Syndrome Helicase Compresses Single‐Stranded DNA into Phase‐Separated Condensates. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Teng Wang
- ShanghaiTech University - Zhangjiang Campus: ShanghaiTech University School of Life Science and Technology CHINA
| | - Jiaojiao Hu
- Shanghai Institute of Organic Chemistry Interdisciplinary Research Center on Biology and Chemistry CHINA
| | - Yanan Li
- ShanghaiTech University - Zhangjiang Campus: ShanghaiTech University School of Life Science and Technology CHINA
| | - Lulu Bi
- ShanghaiTech University - Zhangjiang Campus: ShanghaiTech University School of Life Science and Technology CHINA
| | - Lijuan Guo
- ShanghaiTech University - Zhangjiang Campus: ShanghaiTech University School of Life Science and Technology CHINA
| | - Xinshuo Jia
- ShanghaiTech University - Zhangjiang Campus: ShanghaiTech University School of Life Science and Technology CHINA
| | - Xia Zhang
- ShanghaiTech University - Zhangjiang Campus: ShanghaiTech University School of Life Science and Technology CHINA
| | - Dan Li
- Shanghai Jiao Tong University Bio-X Institutes CHINA
| | - Xi-Miao Hou
- Northwest Agriculture University: Northwest Agriculture and Forestry University College of Life Sciences CHINA
| | - Mauro Modesti
- Aix-Marseille Universite Cancer Research Center of Marseille FRANCE
| | - Xu-Guang Xi
- Northwest A&F University: Northwest Agriculture and Forestry University College of Life Sciences CHINA
| | - Cong Liu
- Shanghai Institute of Organic Chemistry Interdisciplinary Research Center on Biology and Chemistry CHINA
| | - BO SUN
- ShanghaiTech University School of Life Science and Technology 393 Central Huaxia RoadPudong District 201210 Shanghai CHINA
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48
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Kar M, Dar F, Welsh TJ, Vogel LT, Kühnemuth R, Majumdar A, Krainer G, Franzmann TM, Alberti S, Seidel CAM, Knowles TPJ, Hyman AA, Pappu RV. Phase-separating RNA-binding proteins form heterogeneous distributions of clusters in subsaturated solutions. Proc Natl Acad Sci U S A 2022; 119:e2202222119. [PMID: 35787038 DOI: 10.1101/2022.02.03.478969] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
Macromolecular phase separation is thought to be one of the processes that drives the formation of membraneless biomolecular condensates in cells. The dynamics of phase separation are thought to follow the tenets of classical nucleation theory, and, therefore, subsaturated solutions should be devoid of clusters with more than a few molecules. We tested this prediction using in vitro biophysical studies to characterize subsaturated solutions of phase-separating RNA-binding proteins with intrinsically disordered prion-like domains and RNA-binding domains. Surprisingly, and in direct contradiction to expectations from classical nucleation theory, we find that subsaturated solutions are characterized by the presence of heterogeneous distributions of clusters. The distributions of cluster sizes, which are dominated by small species, shift continuously toward larger sizes as protein concentrations increase and approach the saturation concentration. As a result, many of the clusters encompass tens to hundreds of molecules, while less than 1% of the solutions are mesoscale species that are several hundred nanometers in diameter. We find that cluster formation in subsaturated solutions and phase separation in supersaturated solutions are strongly coupled via sequence-encoded interactions. We also find that cluster formation and phase separation can be decoupled using solutes as well as specific sets of mutations. Our findings, which are concordant with predictions for associative polymers, implicate an interplay between networks of sequence-specific and solubility-determining interactions that, respectively, govern cluster formation in subsaturated solutions and the saturation concentrations above which phase separation occurs.
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Affiliation(s)
- Mrityunjoy Kar
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
| | - Furqan Dar
- Department of Physics, Washington University in St. Louis, St. Louis, MO 63130
| | - Timothy J Welsh
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Laura T Vogel
- Department of Molecular Physical Chemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Ralf Kühnemuth
- Department of Molecular Physical Chemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Anupa Majumdar
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
| | - Georg Krainer
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Titus M Franzmann
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, 01069 Dresden, Germany
| | - Simon Alberti
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, 01069 Dresden, Germany
| | - Claus A M Seidel
- Department of Molecular Physical Chemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
- Cavendish Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
| | - Anthony A Hyman
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
| | - Rohit V Pappu
- Department of Biomedical Engineering, Center for Science & Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130
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49
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Kar M, Dar F, Welsh TJ, Vogel LT, Kühnemuth R, Majumdar A, Krainer G, Franzmann TM, Alberti S, Seidel CAM, Knowles TPJ, Hyman AA, Pappu RV. Phase-separating RNA-binding proteins form heterogeneous distributions of clusters in subsaturated solutions. Proc Natl Acad Sci U S A 2022; 119:e2202222119. [PMID: 35787038 PMCID: PMC9282234 DOI: 10.1073/pnas.2202222119] [Citation(s) in RCA: 115] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 05/26/2022] [Indexed: 12/14/2022] Open
Abstract
Macromolecular phase separation is thought to be one of the processes that drives the formation of membraneless biomolecular condensates in cells. The dynamics of phase separation are thought to follow the tenets of classical nucleation theory, and, therefore, subsaturated solutions should be devoid of clusters with more than a few molecules. We tested this prediction using in vitro biophysical studies to characterize subsaturated solutions of phase-separating RNA-binding proteins with intrinsically disordered prion-like domains and RNA-binding domains. Surprisingly, and in direct contradiction to expectations from classical nucleation theory, we find that subsaturated solutions are characterized by the presence of heterogeneous distributions of clusters. The distributions of cluster sizes, which are dominated by small species, shift continuously toward larger sizes as protein concentrations increase and approach the saturation concentration. As a result, many of the clusters encompass tens to hundreds of molecules, while less than 1% of the solutions are mesoscale species that are several hundred nanometers in diameter. We find that cluster formation in subsaturated solutions and phase separation in supersaturated solutions are strongly coupled via sequence-encoded interactions. We also find that cluster formation and phase separation can be decoupled using solutes as well as specific sets of mutations. Our findings, which are concordant with predictions for associative polymers, implicate an interplay between networks of sequence-specific and solubility-determining interactions that, respectively, govern cluster formation in subsaturated solutions and the saturation concentrations above which phase separation occurs.
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Affiliation(s)
- Mrityunjoy Kar
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
| | - Furqan Dar
- Department of Physics, Washington University in St. Louis, St. Louis, MO 63130
| | - Timothy J. Welsh
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Laura T. Vogel
- Department of Molecular Physical Chemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Ralf Kühnemuth
- Department of Molecular Physical Chemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Anupa Majumdar
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
| | - Georg Krainer
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - Titus M. Franzmann
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, 01069 Dresden, Germany
| | - Simon Alberti
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, 01069 Dresden, Germany
| | - Claus A. M. Seidel
- Department of Molecular Physical Chemistry, Heinrich Heine University, 40225 Düsseldorf, Germany
| | - Tuomas P. J. Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
- Cavendish Laboratory, University of Cambridge, CB3 0HE Cambridge, United Kingdom
| | - Anthony A. Hyman
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
| | - Rohit V. Pappu
- Department of Biomedical Engineering, Center for Science & Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130
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50
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Mittag T, Pappu RV. A conceptual framework for understanding phase separation and addressing open questions and challenges. Mol Cell 2022; 82:2201-2214. [PMID: 35675815 PMCID: PMC9233049 DOI: 10.1016/j.molcel.2022.05.018] [Citation(s) in RCA: 265] [Impact Index Per Article: 132.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 05/04/2022] [Accepted: 05/13/2022] [Indexed: 12/11/2022]
Abstract
Macromolecular phase separation is being recognized for its potential importance and relevance as a driver of spatial organization within cells. Here, we describe a framework based on synergies between networking (percolation or gelation) and density (phase separation) transitions. Accordingly, the phase transitions in question are referred to as phase separation coupled to percolation (PSCP). The condensates that result from PSCP are viscoelastic network fluids. Such systems have sequence-, composition-, and topology-specific internal network structures that give rise to time-dependent interplays between viscous and elastic properties. Unlike pure phase separation, the process of PSCP gives rise to sequence-, chemistry-, and structure-specific distributions of clusters that can form at concentrations that lie well below the threshold concentration for phase separation. PSCP, influenced by specific versus solubility-determining interactions, also provides a bridge between different observations and helps answer questions and address challenges that have arisen regarding the role of macromolecular phase separation in biology.
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Affiliation(s)
- Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
| | - Rohit V Pappu
- Department of Biomedical Engineering and Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO 63130, USA.
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