1
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Hoffmann ME, Jacomin AC, Popovic D, Kalina D, Covarrubias-Pinto A, Dikic I. TBC1D2B undergoes phase separation and mediates autophagy initiation. J Cell Biochem 2024; 125:e30481. [PMID: 38226533 DOI: 10.1002/jcb.30481] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 08/28/2023] [Accepted: 09/17/2023] [Indexed: 01/17/2024]
Abstract
Small ubiquitin-like modifiers from the ATG8 family regulate autophagy initiation and progression in mammalian cells. Their interaction with LC3-interacting region (LIR) containing proteins promotes cargo sequestration, phagophore assembly, or even fusion between autophagosomes and lysosomes. Previously, we have shown that RabGAP proteins from the TBC family directly bind to LC3/GABARAP proteins. In the present study, we focus on the function of TBC1D2B. We show that TBC1D2B contains a functional canonical LIR motif and acts at an early stage of autophagy by binding to both LC3/GABARAP and ATG12 conjugation complexes. Subsequently, TBC1D2B is degraded by autophagy. TBC1D2B condensates into liquid droplets upon autophagy induction. Our study suggests that phase separation is an underlying mechanism of TBC1D2B-dependent autophagy induction.
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Affiliation(s)
- Marina E Hoffmann
- Molecular Signaling Group, Institute of Biochemistry II, Medical Faculty, Goethe University Frankfurt, Frankfurt, Germany
| | - Anne-Claire Jacomin
- Molecular Signaling Group, Institute of Biochemistry II, Medical Faculty, Goethe University Frankfurt, Frankfurt, Germany
| | - Doris Popovic
- Molecular Signaling Group, Institute of Biochemistry II, Medical Faculty, Goethe University Frankfurt, Frankfurt, Germany
| | - Daniel Kalina
- Molecular Signaling Group, Institute of Biochemistry II, Medical Faculty, Goethe University Frankfurt, Frankfurt, Germany
- Biomedical Research Laboratory, Department of Internal Medicine, Goethe University Clinic Frankfurt, Frankfurt, Germany
| | - Adriana Covarrubias-Pinto
- Molecular Signaling Group, Institute of Biochemistry II, Medical Faculty, Goethe University Frankfurt, Frankfurt, Germany
| | - Ivan Dikic
- Molecular Signaling Group, Institute of Biochemistry II, Medical Faculty, Goethe University Frankfurt, Frankfurt, Germany
- Molecular Signaling Group, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Branch for Translational Medicine and Pharmacology, Fraunhofer Institute of Translational Medicine and Pharmacology ITMP, Frankfurt, Germany
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2
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Jung J, Tan C, Sugita Y. GENESIS CGDYN: large-scale coarse-grained MD simulation with dynamic load balancing for heterogeneous biomolecular systems. Nat Commun 2024; 15:3370. [PMID: 38643169 PMCID: PMC11032353 DOI: 10.1038/s41467-024-47654-1] [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: 09/07/2023] [Accepted: 04/08/2024] [Indexed: 04/22/2024] Open
Abstract
Residue-level coarse-grained (CG) molecular dynamics (MD) simulation is widely used to investigate slow biological processes that involve multiple proteins, nucleic acids, and their complexes. Biomolecules in a large simulation system are distributed non-uniformly, limiting computational efficiency with conventional methods. Here, we develop a hierarchical domain decomposition scheme with dynamic load balancing for heterogeneous biomolecular systems to keep computational efficiency even after drastic changes in particle distribution. These schemes are applied to the dynamics of intrinsically disordered protein (IDP) droplets. During the fusion of two droplets, we find that the changes in droplet shape correlate with the mixing of IDP chains. Additionally, we simulate large systems with multiple IDP droplets, achieving simulation sizes comparable to those observed in microscopy. In our MD simulations, we directly observe Ostwald ripening, a phenomenon where small droplets dissolve and their molecules redeposit into larger droplets. These methods have been implemented in CGDYN of the GENESIS software, offering a tool for investigating mesoscopic biological processes using the residue-level CG models.
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Affiliation(s)
- Jaewoon Jung
- Computational Biophysics Research Team, RIKEN Center for Computational Science, Kobe, Hyogo, 650-0047, Japan
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, 351-0198, Japan
| | - Cheng Tan
- Computational Biophysics Research Team, RIKEN Center for Computational Science, Kobe, Hyogo, 650-0047, Japan
| | - Yuji Sugita
- Computational Biophysics Research Team, RIKEN Center for Computational Science, Kobe, Hyogo, 650-0047, Japan.
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, 351-0198, Japan.
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo, 650-0047, Japan.
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3
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Li C, Hao B, Yang H, Wang K, Fan L, Xiao W. Protein aggregation and biomolecular condensation in hypoxic environments (Review). Int J Mol Med 2024; 53:33. [PMID: 38362920 PMCID: PMC10903932 DOI: 10.3892/ijmm.2024.5357] [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: 11/08/2023] [Accepted: 01/15/2024] [Indexed: 02/17/2024] Open
Abstract
Due to molecular forces, biomacromolecules assemble into liquid condensates or solid aggregates, and their corresponding formation and dissolution processes are controlled. Protein homeostasis is disrupted by increasing age or environmental stress, leading to irreversible protein aggregation. Hypoxic pressure is an important factor in this process, and uncontrolled protein aggregation has been widely observed in hypoxia‑related conditions such as neurodegenerative disease, cardiovascular disease, hypoxic brain injury and cancer. Biomolecular condensates are also high‑order complexes assembled from macromolecules. Although they exist in different phase from protein aggregates, they are in dynamic balance under certain conditions, and their activation or assembly are considered as important regulatory processes in cell survival with hypoxic pressure. Therefore, a better understanding of the relationship between hypoxic stress, protein aggregation and biomolecular condensation will bring marked benefits in the clinical treatment of various diseases. The aim of the present review was to summarize the underlying mechanisms of aggregate assembly and dissolution induced by hypoxic conditions, and address recent breakthroughs in understanding the role of aggregates in hypoxic‑related diseases, given the hypotheses that hypoxia induces macromolecular assemblage changes from a liquid to a solid phase, and that adenosine triphosphate depletion and ATP‑driven inactivation of multiple protein chaperones play important roles among the process. Moreover, it is anticipated that an improved understanding of the adaptation in hypoxic environments could extend the overall survival of patients and provide new strategies for hypoxic‑related diseases.
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Affiliation(s)
- Chaoqun Li
- School of Exercise and Health, Shanghai University of Sport, Shanghai 200438, P.R. China
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Bingjie Hao
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Haiguang Yang
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Kai Wang
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Lihong Fan
- School of Exercise and Health, Shanghai University of Sport, Shanghai 200438, P.R. China
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Weihua Xiao
- School of Exercise and Health, Shanghai University of Sport, Shanghai 200438, P.R. China
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4
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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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5
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Campelo F, Tian M, von Blume J. Rediscovering the intricacies of secretory granule biogenesis. Curr Opin Cell Biol 2023; 85:102231. [PMID: 37657367 DOI: 10.1016/j.ceb.2023.102231] [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: 06/16/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 09/03/2023]
Abstract
Regulated secretion, an essential cellular process, relies on secretory granules (SGs) for the controlled release of a diverse range of cargo molecules, including proteins, peptides, hormones, enzymes, and neurotransmitters. SG biogenesis encompasses cargo selection, sorting, packaging, and trafficking, with the trans-Golgi Network (TGN) playing a central role. Research in the last three decades has revealed significant components required for SG biogenesis; however, no cargo receptor transferring granule cargo from the TGN to immature SGs (ISGs) has yet been identified. Consequently, recent research has devoted significant attention to studying receptor-independent cargo sorting mechanisms, shedding new light on the complexities of regulated secretion. Understanding the underlying molecular and biophysical mechanisms behind cargo sorting into ISGs holds great promise for advancing our knowledge of cellular communication and disease mechanisms.
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Affiliation(s)
- Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels, Barcelona, Spain
| | - Meng Tian
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Julia von Blume
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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6
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Saar KL, Qian D, Good LL, Morgunov AS, Collepardo-Guevara R, Best RB, Knowles TPJ. Theoretical and Data-Driven Approaches for Biomolecular Condensates. Chem Rev 2023; 123:8988-9009. [PMID: 37171907 PMCID: PMC10375482 DOI: 10.1021/acs.chemrev.2c00586] [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: 08/23/2022] [Indexed: 05/14/2023]
Abstract
Biomolecular condensation processes are increasingly recognized as a fundamental mechanism that living cells use to organize biomolecules in time and space. These processes can lead to the formation of membraneless organelles that enable cells to perform distinct biochemical processes in controlled local environments, thereby supplying them with an additional degree of spatial control relative to that achieved by membrane-bound organelles. This fundamental importance of biomolecular condensation has motivated a quest to discover and understand the molecular mechanisms and determinants that drive and control this process. Within this molecular viewpoint, computational methods can provide a unique angle to studying biomolecular condensation processes by contributing the resolution and scale that are challenging to reach with experimental techniques alone. In this Review, we focus on three types of dry-lab approaches: theoretical methods, physics-driven simulations and data-driven machine learning methods. We review recent progress in using these tools for probing biomolecular condensation across all three fields and outline the key advantages and limitations of each of the approaches. We further discuss some of the key outstanding challenges that we foresee the community addressing next in order to develop a more complete picture of the molecular driving forces behind biomolecular condensation processes and their biological roles in health and disease.
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Affiliation(s)
- Kadi L. Saar
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Transition
Bio Ltd., Cambridge, United Kingdom
| | - Daoyuan Qian
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Lydia L. Good
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Laboratory
of Chemical Physics, National Institute of Diabetes and Digestive
and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United States
| | - Alexey S. Morgunov
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Rosana Collepardo-Guevara
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Department
of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Robert B. Best
- Laboratory
of Chemical Physics, National Institute of Diabetes and Digestive
and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United States
| | - Tuomas P. J. Knowles
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Cavendish
Laboratory, Department of Physics, University
of Cambridge, Cambridge CB3 0HE, United Kingdom
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7
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Sanchez-Burgos I, Herriott L, Collepardo-Guevara R, Espinosa JR. Surfactants or scaffolds? RNAs of varying lengths control the thermodynamic stability of condensates differently. Biophys J 2023; 122:2973-2987. [PMID: 36883003 PMCID: PMC10398262 DOI: 10.1016/j.bpj.2023.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 02/23/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Biomolecular condensates, thought to form via liquid-liquid phase separation of intracellular mixtures, are multicomponent systems that can include diverse types of proteins and RNAs. RNA is a critical modulator of RNA-protein condensate stability, as it induces an RNA concentration-dependent reentrant phase transition-increasing stability at low RNA concentrations and decreasing it at high concentrations. Beyond concentration, RNAs inside condensates can be heterogeneous in length, sequence, and structure. Here, we use multiscale simulations to understand how different RNA parameters interact with one another to modulate the properties of RNA-protein condensates. To do so, we perform residue/nucleotide resolution coarse-grained molecular dynamics simulations of multicomponent RNA-protein condensates containing RNAs of different lengths and concentrations, and either FUS or PR25 proteins. Our simulations reveal that RNA length regulates the reentrant phase behavior of RNA-protein condensates: increasing RNA length sensitively rises the maximum value that the critical temperature of the mixture reaches, and the maximum concentration of RNA that the condensate can incorporate before beginning to become unstable. Strikingly, RNAs of different lengths are organized heterogeneously inside condensates, which allows them to enhance condensate stability via two distinct mechanisms: shorter RNA chains accumulate at the condensate's surface acting as natural biomolecular surfactants, while longer RNA chains concentrate inside the core to saturate their bonds and enhance the density of molecular connections in the condensate. Using a patchy particle model, we additionally demonstrate that the combined impact of RNA length and concentration on condensate properties is dictated by the valency, binding affinity, and polymer length of the various biomolecules involved. Our results postulate that diversity on RNA parameters within condensates allows RNAs to increase condensate stability by fulfilling two different criteria: maximizing enthalpic gain and minimizing interfacial free energy; hence, RNA diversity should be considered when assessing the impact of RNA on biomolecular condensates regulation.
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Affiliation(s)
- Ignacio Sanchez-Burgos
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Lara Herriott
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Rosana Collepardo-Guevara
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Departament of Chemical Physics, Faculty of Chemical Sciences, Universidad Complutense de Madrid, Madrid, Spain.
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8
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Rothé B, Fortier S, Gagnieux C, Schmuziger C, Constam DB. Antagonistic interactions among structured domains in the multivalent Bicc1-ANKS3-ANKS6 protein network govern phase transitioning of target mRNAs. iScience 2023; 26:106855. [PMID: 37275520 PMCID: PMC10232731 DOI: 10.1016/j.isci.2023.106855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 04/11/2023] [Accepted: 05/05/2023] [Indexed: 06/07/2023] Open
Abstract
The growing number of diseases linked to aberrant phase transitioning of ribonucleoproteins highlights the need to uncover how the interplay between multivalent protein and RNA interactions is regulated. Cytoplasmic granules of the RNA binding protein Bicaudal-C (Bicc1) are regulated by the ciliopathy proteins ankyrin (ANK) and sterile alpha motif (SAM) domain-containing ANKS3 and ANKS6, but whether and how target mRNAs are affected is unknown. Here, we show that head-to-tail polymers of Bicc1 nucleated by its SAM domain are interconnected by K homology (KH) domains in a protein meshwork that mediates liquid-to-gel transitioning of client transcripts. Moreover, while the dispersion of these granules by ANKS3 concomitantly released bound mRNAs, co-recruitment of ANKS6 by ANKS3 reinstated Bicc1 condensation and ribonucleoparticle assembly. RNA-independent Bicc1 polymerization and its dual regulation by ANKS3 and ANKS6 represent a new mechanism to couple the reversible immobilization of client mRNAs to controlled protein phase transitioning between distinct metastable states.
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Affiliation(s)
- Benjamin Rothé
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Simon Fortier
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Céline Gagnieux
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Céline Schmuziger
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
| | - Daniel B. Constam
- Ecole Polytechnique Fédérale de Lausanne (EPFL) SV ISREC, Station 19, 1015 Lausanne, Switzerland
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9
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Abstract
Biomolecular condensates constitute a newly recognized form of spatial organization in living cells. Although many condensates are believed to form as a result of phase separation, the physicochemical properties that determine the phase behavior of heterogeneous biomolecular mixtures are only beginning to be explored. Theory and simulation provide invaluable tools for probing the relationship between molecular determinants, such as protein and RNA sequences, and the emergence of phase-separated condensates in such complex environments. This review covers recent advances in the prediction and computational design of biomolecular mixtures that phase-separate into many coexisting phases. First, we review efforts to understand the phase behavior of mixtures with hundreds or thousands of species using theoretical models and statistical approaches. We then describe progress in developing analytical theories and coarse-grained simulation models to predict multiphase condensates with the molecular detail required to make contact with biophysical experiments. We conclude by summarizing the challenges ahead for modeling the inhomogeneous spatial organization of biomolecular mixtures in living cells.
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Affiliation(s)
- William M Jacobs
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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10
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Hagan MF, Mohajerani F. Self-assembly coupled to liquid-liquid phase separation. PLoS Comput Biol 2023; 19:e1010652. [PMID: 37186597 PMCID: PMC10212142 DOI: 10.1371/journal.pcbi.1010652] [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: 10/12/2022] [Revised: 05/25/2023] [Accepted: 04/26/2023] [Indexed: 05/17/2023] Open
Abstract
Liquid condensate droplets with distinct compositions of proteins and nucleic acids are widespread in biological cells. While it is known that such droplets, or compartments, can regulate irreversible protein aggregation, their effect on reversible self-assembly remains largely unexplored. In this article, we use kinetic theory and solution thermodynamics to investigate the effect of liquid-liquid phase separation on the reversible self-assembly of structures with well-defined sizes and architectures. We find that, when assembling subunits preferentially partition into liquid compartments, robustness against kinetic traps and maximum achievable assembly rates can be significantly increased. In particular, both the range of solution conditions leading to productive assembly and the corresponding assembly rates can increase by orders of magnitude. We analyze the rate equation predictions using simple scaling estimates to identify effects of liquid-liquid phase separation as a function of relevant control parameters. These results may elucidate self-assembly processes that underlie normal cellular functions or pathogenesis, and suggest strategies for designing efficient bottom-up assembly for nanomaterials applications.
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Affiliation(s)
- Michael F. Hagan
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts, United States of America
| | - Farzaneh Mohajerani
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts, United States of America
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11
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Chew PY, Joseph JA, Collepardo-Guevara R, Reinhardt A. Thermodynamic origins of two-component multiphase condensates of proteins. Chem Sci 2023; 14:1820-1836. [PMID: 36819870 PMCID: PMC9931050 DOI: 10.1039/d2sc05873a] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 01/06/2023] [Indexed: 01/26/2023] Open
Abstract
Intracellular condensates are highly multi-component systems in which complex phase behaviour can ensue, including the formation of architectures comprising multiple immiscible condensed phases. Relying solely on physical intuition to manipulate such condensates is difficult because of the complexity of their composition, and systematically learning the underlying rules experimentally would be extremely costly. We address this challenge by developing a computational approach to design pairs of protein sequences that result in well-separated multilayered condensates and elucidate the molecular origins of these compartments. Our method couples a genetic algorithm to a residue-resolution coarse-grained protein model. We demonstrate that we can design protein partners to form multiphase condensates containing naturally occurring proteins, such as the low-complexity domain of hnRNPA1 and its mutants, and show how homo- and heterotypic interactions must differ between proteins to result in multiphasicity. We also show that in some cases the specific pattern of amino-acid residues plays an important role. Our findings have wide-ranging implications for understanding and controlling the organisation, functions and material properties of biomolecular condensates.
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Affiliation(s)
- Pin Yu Chew
- Yusuf Hamied Department of Chemistry, University of Cambridge Cambridge CB2 1EW UK
| | - Jerelle A. Joseph
- Yusuf Hamied Department of Chemistry, University of CambridgeCambridgeCB2 1EWUK,Department of Physics, University of CambridgeCambridgeCB3 0HEUK,Department of Genetics, University of CambridgeCambridgeCB2 3EHUK
| | - Rosana Collepardo-Guevara
- Yusuf Hamied Department of Chemistry, University of Cambridge Cambridge CB2 1EW UK .,Department of Physics, University of Cambridge Cambridge CB3 0HE UK.,Department of Genetics, University of Cambridge Cambridge CB2 3EH UK
| | - Aleks Reinhardt
- Yusuf Hamied Department of Chemistry, University of Cambridge Cambridge CB2 1EW UK
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12
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Zhorabek F, Abesekara MS, Liu J, Dai X, Huang J, Chau Y. Construction of multiphasic membraneless organelles towards spontaneous spatial segregation and directional flow of biochemical reactions. Chem Sci 2023; 14:801-811. [PMID: 36755726 PMCID: PMC9890938 DOI: 10.1039/d2sc05438h] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/29/2022] [Indexed: 01/15/2023] Open
Abstract
Many intracellular membraneless organelles (MLOs) appear to adapt a hierarchical multicompartment organization for efficient coordination of highly complex reaction networks. Recapitulating such an internal architecture in biomimetic platforms is, therefore, an important step to facilitate the functional understanding of MLOs and to enable the design of advanced microreactors. Herein, we present a modular bottom-up approach for building synthetic multiphasic condensates using a set of engineered multivalent polymer-oligopeptide hybrids. These hybrid constructs exhibit dynamic phase separation behaviour generating membraneless droplets with a subdivided interior featuring distinct chemical and physical properties, whereby a range of functional biomolecules can be spontaneously enriched and spatially segregated. The platform also attains separated confinement of transcription and translation reactions in proximal compartments, while allowing inter-compartment communication via a directional flow of reactants. With advanced structural and functional features attained, this system can be of great value as a MLO model and as a cell-free system for multiplex chemical biosynthesis.
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Affiliation(s)
- Fariza Zhorabek
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology Clear Water Bay, Kowloon Hong Kong SAR China
| | - Manisha Sandupama Abesekara
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology Clear Water Bay, Kowloon Hong Kong SAR China
| | - Jianhui Liu
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology Clear Water Bay, Kowloon Hong Kong SAR China
| | - Xin Dai
- Department of Chemistry, Hong Kong University of Science and TechnologyClear Water Bay, KowloonHong Kong SARChina
| | - Jinqing Huang
- Department of Chemistry, Hong Kong University of Science and TechnologyClear Water Bay, KowloonHong Kong SARChina
| | - Ying Chau
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology Clear Water Bay, Kowloon Hong Kong SAR China
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13
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Chew PY, Reinhardt A. Phase diagrams-Why they matter and how to predict them. J Chem Phys 2023; 158:030902. [PMID: 36681642 DOI: 10.1063/5.0131028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Understanding the thermodynamic stability and metastability of materials can help us to, for example, gauge whether crystalline polymorphs in pharmaceutical formulations are likely to be durable. It can also help us to design experimental routes to novel phases with potentially interesting properties. In this Perspective, we provide an overview of how thermodynamic phase behavior can be quantified both in computer simulations and machine-learning approaches to determine phase diagrams, as well as combinations of the two. We review the basic workflow of free-energy computations for condensed phases, including some practical implementation advice, ranging from the Frenkel-Ladd approach to thermodynamic integration and to direct-coexistence simulations. We illustrate the applications of such methods on a range of systems from materials chemistry to biological phase separation. Finally, we outline some challenges, questions, and practical applications of phase-diagram determination which we believe are likely to be possible to address in the near future using such state-of-the-art free-energy calculations, which may provide fundamental insight into separation processes using multicomponent solvents.
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Affiliation(s)
- Pin Yu Chew
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Aleks Reinhardt
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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14
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Heterotypic electrostatic interactions control complex phase separation of tau and prion into multiphasic condensates and co-aggregates. Proc Natl Acad Sci U S A 2023; 120:e2216338120. [PMID: 36595668 PMCID: PMC9986828 DOI: 10.1073/pnas.2216338120] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Biomolecular condensates formed via phase separation of proteins and nucleic acids are thought to perform a wide range of critical cellular functions by maintaining spatiotemporal regulation and organizing intracellular biochemistry. However, aberrant phase transitions are implicated in a multitude of human diseases. Here, we demonstrate that two neuronal proteins, namely tau and prion, undergo complex coacervation driven by domain-specific electrostatic interactions to yield highly dynamic, mesoscopic liquid-like droplets. The acidic N-terminal segment of tau interacts electrostatically with the polybasic N-terminal intrinsically disordered segment of the prion protein (PrP). We employed a unique combination of time-resolved tools that encompass several orders of magnitude of timescales ranging from nanoseconds to seconds. These studies unveil an intriguing symphony of molecular events associated with the formation of heterotypic condensates comprising ephemeral, domain-specific, short-range electrostatic nanoclusters. Our results reveal that these heterotypic condensates can be tuned by RNA in a stoichiometry-dependent manner resulting in reversible, multiphasic, immiscible, and ternary condensates of different morphologies ranging from core-shell to nested droplets. This ternary system exhibits a typical three-regime phase behavior reminiscent of other membraneless organelles including nucleolar condensates. We also show that upon aging, tau:PrP droplets gradually convert into solid-like co-assemblies by sequestration of persistent intermolecular interactions. Our vibrational Raman results in conjunction with atomic force microscopy and multi-color fluorescence imaging reveal the presence of amorphous and amyloid-like co-aggregates upon maturation. Our findings provide mechanistic underpinnings of overlapping neuropathology involving tau and PrP and highlight a broader biological role of complex phase transitions in physiology and disease.
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15
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Latham AP, Zhang B. Molecular Determinants for the Layering and Coarsening of Biological Condensates. AGGREGATE (HOBOKEN, N.J.) 2022; 3:e306. [PMID: 37065433 PMCID: PMC10101022 DOI: 10.1002/agt2.306] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Many membraneless organelles, or biological condensates, form through phase separation, and play key roles in signal sensing and transcriptional regulation. While the functional importance of these condensates has inspired many studies to characterize their stability and spatial organization, the underlying principles that dictate these emergent properties are still being uncovered. In this review, we examine recent work on biological condensates, especially multicomponent systems. We focus on connecting molecular factors such as binding energy, valency, and stoichiometry with the interfacial tension, explaining the nontrivial interior organization in many condensates. We further discuss mechanisms that arrest condensate coalescence by lowering the surface tension or introducing kinetic barriers to stabilize the multidroplet state.
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Affiliation(s)
- Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139
- Department of Bioengineering and Therapeutic Sciences, University of California at San Francisco, San Francisco, CA 94143
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139
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16
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Alemasova EE, Lavrik OI. A sePARate phase? Poly(ADP-ribose) versus RNA in the organization of biomolecular condensates. Nucleic Acids Res 2022; 50:10817-10838. [PMID: 36243979 DOI: 10.1093/nar/gkac866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 09/14/2022] [Accepted: 10/09/2022] [Indexed: 11/13/2022] Open
Abstract
Condensates are biomolecular assemblies that concentrate biomolecules without the help of membranes. They are morphologically highly versatile and may emerge via distinct mechanisms. Nucleic acids-DNA, RNA and poly(ADP-ribose) (PAR) play special roles in the process of condensate organization. These polymeric scaffolds provide multiple specific and nonspecific interactions during nucleation and 'development' of macromolecular assemblages. In this review, we focus on condensates formed with PAR. We discuss to what extent the literature supports the phase separation origin of these structures. Special attention is paid to similarities and differences between PAR and RNA in the process of dynamic restructuring of condensates during their functioning.
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Affiliation(s)
- Elizaveta E Alemasova
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk 630090, Russia
| | - Olga I Lavrik
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk 630090, Russia.,Novosibirsk State University, Novosibirsk 630090, Russia
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17
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Tejedor AR, Sanchez-Burgos I, Estevez-Espinosa M, Garaizar A, Collepardo-Guevara R, Ramirez J, Espinosa JR. Protein structural transitions critically transform the network connectivity and viscoelasticity of RNA-binding protein condensates but RNA can prevent it. Nat Commun 2022; 13:5717. [PMID: 36175408 PMCID: PMC9522849 DOI: 10.1038/s41467-022-32874-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 08/18/2022] [Indexed: 12/03/2022] Open
Abstract
Biomolecular condensates, some of which are liquid-like during health, can age over time becoming gel-like pathological systems. One potential source of loss of liquid-like properties during ageing of RNA-binding protein condensates is the progressive formation of inter-protein β-sheets. To bridge microscopic understanding between accumulation of inter-protein β-sheets over time and the modulation of FUS and hnRNPA1 condensate viscoelasticity, we develop a multiscale simulation approach. Our method integrates atomistic simulations with sequence-dependent coarse-grained modelling of condensates that exhibit accumulation of inter-protein β-sheets over time. We reveal that inter-protein β-sheets notably increase condensate viscosity but does not transform the phase diagrams. Strikingly, the network of molecular connections within condensates is drastically altered, culminating in gelation when the network of strong β-sheets fully percolates. However, high concentrations of RNA decelerate the emergence of inter-protein β-sheets. Our study uncovers molecular and kinetic factors explaining how the accumulation of inter-protein β-sheets can trigger liquid-to-solid transitions in condensates, and suggests a potential mechanism to slow such transitions down. In this work the authors propose a multiscale computational approach, integrating atomistic and coarse-grained models simulations, to study the thermodynamic and kinetic factors playing a major role in the liquid-to-solid transition of biomolecular condensates. It is revealed how the gradual accumulation of inter-protein β-sheets increases the viscosity of functional liquid-like condensates, transforming them into gel-like pathological aggregates, and it is also shown how high concentrations of RNA can decelerate such transition.
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Affiliation(s)
- Andres R Tejedor
- Department of Chemical Engineering, Universidad Politécnica de Madrid, José Gutiérrez Abascal 2, 28006, Madrid, Spain.,Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Ignacio Sanchez-Burgos
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Maria Estevez-Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.,Department of Biochemistry, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.,Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.,Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Jorge Ramirez
- Department of Chemical Engineering, Universidad Politécnica de Madrid, José Gutiérrez Abascal 2, 28006, Madrid, Spain.
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
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18
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Garg DK, Bhat R. Modulation of assembly of TDP-43 low-complexity domain by heparin: From droplets to amyloid fibrils. Biophys J 2022; 121:2568-2582. [PMID: 35644946 PMCID: PMC9300664 DOI: 10.1016/j.bpj.2022.05.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 09/03/2021] [Accepted: 05/25/2022] [Indexed: 11/02/2022] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is an RNA-regulating protein that carries out many cellular functions through liquid-liquid phase separation (LLPS). The LLPS of TDP-43 is mediated by its C-terminal low-complexity domain (TDP43-LCD) corresponding to the region 267-414. In neurodegenerative disorders amyotrophic lateral sclerosis and frontotemporal dementia, pathological inclusions of the TDP-43 are found that are rich in the C-terminal fragments of ∼25 and ∼35 kDa, of which TDP43-LCD is a part. Thus, understanding the assembly process of TDP43-LCD is essential, given its involvement in the formation of both functional liquid-like assemblies and solid- or gel-like pathological aggregates. Here, we show that the solution pH and salt modulate TDP43-LCD LLPS. A gradual reduction in the pH below its isoelectric point of 9.8 results in a monotonic decrease of TDP43-LCD LLPS due to charge-charge repulsion between monomers, while at pH 6 and below no LLPS was observed. The addition of heparin to TDP43-LCD solution at pH 6, at a 1:2 heparin-to-TDP43-LCD molar ratio, promotes TDP43-LCD LLPS, while at higher concentration, it disrupts LLPS through a reentrant phase transition. Upon incubation at pH 6, TDP43-LCD undergoes gelation without phase separation. However, in the reentrant regime in the presence of a high heparin concentration, it forms thick amyloid aggregates that are significantly more SDS resistant than the gel. The results indicate that the material nature of the TDP43-LCD assembly products can be modulated by heparin which is significant in the context of liquid-to-solid phase transition observed in TDP-43 proteinopathies. Our findings are also crucial in relation to similar transitions that could occur due to alteration in the molecular level interactions among various multivalent biomolecules involving other LCDs and RNAs.
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Affiliation(s)
| | - Rajiv Bhat
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.
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19
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Tsidilkovski L, Mohajerani F, Hagan MF. Microcompartment assembly around multicomponent fluid cargoes. J Chem Phys 2022; 156:245104. [PMID: 35778087 PMCID: PMC9249432 DOI: 10.1063/5.0089556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This article describes dynamical simulations of the assembly of an icosahedral protein shell around a bicomponent fluid cargo. Our simulations are motivated by bacterial microcompartments, which are protein shells found in bacteria that assemble around a complex of enzymes and other components involved in certain metabolic processes. The simulations demonstrate that the relative interaction strengths among the different cargo species play a key role in determining the amount of each species that is encapsulated, their spatial organization, and the nature of the shell assembly pathways. However, the shell protein–shell protein and shell protein–cargo component interactions that help drive assembly and encapsulation also influence cargo composition within certain parameter regimes. These behaviors are governed by a combination of thermodynamic and kinetic effects. In addition to elucidating how natural microcompartments encapsulate multiple components involved within reaction cascades, these results have implications for efforts in synthetic biology to colocalize alternative sets of molecules within microcompartments to accelerate specific reactions. More broadly, the results suggest that coupling between self-assembly and multicomponent liquid–liquid phase separation may play a role in the organization of the cellular cytoplasm.
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Affiliation(s)
- Lev Tsidilkovski
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Farzaneh Mohajerani
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Michael F Hagan
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
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20
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Mazarakos K, Zhou HX. Multiphase Organization Is a Second Phase Transition Within Multi-Component Biomolecular Condensates. J Chem Phys 2022; 156:191104. [DOI: 10.1063/5.0088004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a mean-field theoretical model, along with molecular dynamics simulations, to show that the multiphase organization of multi-component condensates is a second phase transition. Whereas the first phase transition that leads to the separation of condensates from the bulk phase is driven by overall attraction among the macromolecular components, the second phase transition can be driven by the disparity in strength between self and cross-species attraction. At a fixed level of disparity in interaction strengths, both of the phase transitions can be observed by decreasing temperature, leading first to the separation of condensates from the bulk phase and then to component demixing inside condensates. The existence of a critical temperature for demixing and predicted binodals are verified by molecular dynamics simulations of model mixtures.
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Affiliation(s)
| | - Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago, United States of America
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21
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Spatiotemporal modulations in heterotypic condensates of prion and α-synuclein control phase transitions and amyloid conversion. Nat Commun 2022; 13:1154. [PMID: 35241680 PMCID: PMC8894376 DOI: 10.1038/s41467-022-28797-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 02/10/2022] [Indexed: 12/30/2022] Open
Abstract
Biomolecular condensation via liquid-liquid phase separation of proteins and nucleic acids is associated with a range of critical cellular functions and neurodegenerative diseases. Here, we demonstrate that complex coacervation of the prion protein and α-synuclein within narrow stoichiometry results in the formation of highly dynamic, reversible, thermo-responsive liquid droplets via domain-specific electrostatic interactions between the positively-charged intrinsically disordered N-terminal segment of prion and the acidic C-terminal tail of α-synuclein. The addition of RNA to these coacervates yields multiphasic, vesicle-like, hollow condensates. Picosecond time-resolved measurements revealed the presence of transient electrostatic nanoclusters that are stable on the nanosecond timescale and can undergo breaking-and-making of interactions on slower timescales giving rise to a liquid-like behavior in the mesoscopic regime. The liquid-to-solid transition drives a rapid conversion of complex coacervates into heterotypic amyloids. Our results suggest that synergistic prion-α-synuclein interactions within condensates provide mechanistic underpinnings of their physiological role and overlapping neuropathological features. The authors show that prion protein and α-synuclein undergo phase separation through domain-specific electrostatic interactions. These complex coacervates possess electrostatic nanoclusters and can convert into multiphasic condensates and amyloids.
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22
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Valentino M, Ortega BM, Ulrich B, Doyle DA, Farnum ED, Joiner DA, Gavis ER, Niepielko MG. Computational modeling offers new insight into Drosophila germ granule development. Biophys J 2022; 121:1465-1482. [PMID: 35288123 PMCID: PMC9072583 DOI: 10.1016/j.bpj.2022.03.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 02/04/2022] [Accepted: 03/09/2022] [Indexed: 11/02/2022] Open
Abstract
The packaging of specific mRNAs into ribonucleoprotein granules called germ granules is required for germline proliferation and maintenance. During Drosophila germ granule development, mRNAs such as nanos (nos) and polar granule component (pgc) localize to germ granules through a stochastic seeding and self-recruitment process that generates homotypic clusters: aggregates containing multiple copies of a specific transcript. Germ granules vary in mRNA composition with respect to the different transcripts that they contain and their quantity. However, what influences germ granule mRNA composition during development is unclear. To gain insight into how germ granule mRNA heterogeneity arises, we created a computational model that simulates granule development. Although the model includes known mechanisms that were converted into mathematical representations, additional unreported mechanisms proved to be essential for modeling germ granule formation. The model was validated by predicting defects caused by changes in mRNA and protein abundance. Broader application of the model was demonstrated by quantifying nos and pgc localization efficacies and the contribution that an element within the nos 3' untranslated region has on clustering. For the first time, a mathematical representation of Drosophila germ granule formation is described, offering quantitative insight into how mRNA compositions arise while providing a new tool for guiding future studies.
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23
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Rohli KE, Boyer CK, Blom SE, Stephens SB. Nutrient Regulation of Pancreatic Islet β-Cell Secretory Capacity and Insulin Production. Biomolecules 2022; 12:335. [PMID: 35204835 PMCID: PMC8869698 DOI: 10.3390/biom12020335] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 01/27/2023] Open
Abstract
Pancreatic islet β-cells exhibit tremendous plasticity for secretory adaptations that coordinate insulin production and release with nutritional demands. This essential feature of the β-cell can allow for compensatory changes that increase secretory output to overcome insulin resistance early in Type 2 diabetes (T2D). Nutrient-stimulated increases in proinsulin biosynthesis may initiate this β-cell adaptive compensation; however, the molecular regulators of secretory expansion that accommodate the increased biosynthetic burden of packaging and producing additional insulin granules, such as enhanced ER and Golgi functions, remain poorly defined. As these adaptive mechanisms fail and T2D progresses, the β-cell succumbs to metabolic defects resulting in alterations to glucose metabolism and a decline in nutrient-regulated secretory functions, including impaired proinsulin processing and a deficit in mature insulin-containing secretory granules. In this review, we will discuss how the adaptative plasticity of the pancreatic islet β-cell's secretory program allows insulin production to be carefully matched with nutrient availability and peripheral cues for insulin signaling. Furthermore, we will highlight potential defects in the secretory pathway that limit or delay insulin granule biosynthesis, which may contribute to the decline in β-cell function during the pathogenesis of T2D.
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Affiliation(s)
- Kristen E. Rohli
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Cierra K. Boyer
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Sandra E. Blom
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Samuel B. Stephens
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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24
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Sanchez-Burgos I, Espinosa JR, Joseph JA, Collepardo-Guevara R. RNA length has a non-trivial effect in the stability of biomolecular condensates formed by RNA-binding proteins. PLoS Comput Biol 2022; 18:e1009810. [PMID: 35108264 PMCID: PMC8896709 DOI: 10.1371/journal.pcbi.1009810] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 03/04/2022] [Accepted: 01/06/2022] [Indexed: 12/29/2022] Open
Abstract
Biomolecular condensates formed via liquid-liquid phase separation (LLPS) play a crucial role in the spatiotemporal organization of the cell material. Nucleic acids can act as critical modulators in the stability of these protein condensates. To unveil the role of RNA length in regulating the stability of RNA binding protein (RBP) condensates, we present a multiscale computational strategy that exploits the advantages of a sequence-dependent coarse-grained representation of proteins and a minimal coarse-grained model wherein proteins are described as patchy colloids. We find that for a constant nucleotide/protein ratio, the protein fused in sarcoma (FUS), which can phase separate on its own-i.e., via homotypic interactions-only exhibits a mild dependency on the RNA strand length. In contrast, the 25-repeat proline-arginine peptide (PR25), which does not undergo LLPS on its own at physiological conditions but instead exhibits complex coacervation with RNA-i.e., via heterotypic interactions-shows a strong dependence on the length of the RNA strands. Our minimal patchy particle simulations suggest that the strikingly different effect of RNA length on homotypic LLPS versus RBP-RNA complex coacervation is general. Phase separation is RNA-length dependent whenever the relative contribution of heterotypic interactions sustaining LLPS is comparable or higher than those stemming from protein homotypic interactions. Taken together, our results contribute to illuminate the intricate physicochemical mechanisms that influence the stability of RBP condensates through RNA inclusion.
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Affiliation(s)
- Ignacio Sanchez-Burgos
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, United Kingdom
| | - Jorge R. Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, United Kingdom
| | - Jerelle A. Joseph
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, United Kingdom
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, United Kingdom
- Department of Genetics, University of Cambridge, Downing Site, Cambridge, United Kingdom
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, United Kingdom
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, United Kingdom
- Department of Genetics, University of Cambridge, Downing Site, Cambridge, United Kingdom
- * E-mail:
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25
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Surface tension and super-stoichiometric surface enrichment in two-component biomolecular condensates. iScience 2022; 25:103852. [PMID: 35198903 PMCID: PMC8851291 DOI: 10.1016/j.isci.2022.103852] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 12/28/2021] [Accepted: 01/26/2022] [Indexed: 11/24/2022] Open
Abstract
Cells can achieve internal organization by exploiting liquid-liquid phase separation to form biomolecular condensates. Here we focus on the surface properties of condensates composed of two multivalent associative polymers held together by one-to-one “sticker” bonds. Using coarse-grained molecular-dynamics simulations, we study the influence of component stoichiometry on condensate surface properties. We find that unequal stoichiometry results in enrichment of the majority species at the interface and a sharp reduction of surface tension. To relate these two effects, we show that the reduction in surface tension scales linearly with the excess concentration of free binding sites at the interface. Our results imply that each excess free site contributes an approximately fixed additional energy and entropy to the interface, with the latter dominating such that enrichment of free majority sites lowers the surface tension. Our work provides insight into novel physical mechanisms by which cells can regulate condensate surface properties. Stoichiometry controls the surface tension of two-component biomolecular condensates Unequal stoichiometry leads to enrichment of the majority species at the interface Enrichment of the free majority binding sites increases the interfacial entropy Surface tension is drastically reduced at unequal stoichiometry
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26
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Wurmser A, Basu S. Enhancer-Promoter Communication: It's Not Just About Contact. Front Mol Biosci 2022; 9:867303. [PMID: 35517868 PMCID: PMC9061983 DOI: 10.3389/fmolb.2022.867303] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/24/2022] [Indexed: 11/13/2022] Open
Abstract
Cis-regulatory elements such as enhancers can be located even a million base pairs away from their cognate promoter and yet modulate gene transcription. Indeed, the 3D organisation of chromatin enables the establishment of long-range enhancer-promoter communication. The observation of long-range enhancer-promoter chromatin loops at active genes originally led to a model in which enhancers and promoters form physical contacts between each other to control transcription. Yet, recent microscopy data has challenged this prevailing activity-by-contact model of enhancer-promoter communication in transcriptional activation. Live single-cell imaging approaches do not systematically reveal a correlation between enhancer-proximity and transcriptional activation. We therefore discuss the need to move from a static to a dynamic view of enhancer-promoter relationships. We highlight recent studies that not only reveal considerable chromatin movement in specific cell types, but suggest links between chromatin compaction, chromatin movement and transcription. We describe the interplay between enhancer-promoter proximity within the context of biomolecular condensates and the need to understand how condensate microenvironments influence the chromatin binding kinetics of proteins that bind at cis-regulatory elements to activate transcription. Finally, given the complex multi-scale interplay between regulatory proteins, enhancer-promoter proximity and movement, we propose the need to integrate information from complementary single-cell next-generation sequencing and live-cell imaging approaches to derive unified 3D theoretical models of enhancer-promoter communication that are ultimately predictive of transcriptional output and cell fate. In time, improved models will shed light on how tissues grow and diseases emerge.
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Affiliation(s)
- Annabelle Wurmser
- Wellcome-MRC Cambridge Stem Cell Institute, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Srinjan Basu
- Wellcome-MRC Cambridge Stem Cell Institute, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.,Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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27
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Tejedor AR, Garaizar A, Ramírez J, Espinosa JR. 'RNA modulation of transport properties and stability in phase-separated condensates. Biophys J 2021; 120:5169-5186. [PMID: 34762868 DOI: 10.1101/2021.03.05.434111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/03/2021] [Indexed: 05/25/2023] Open
Abstract
One of the key mechanisms employed by cells to control their spatiotemporal organization is the formation and dissolution of phase-separated condensates. The balance between condensate assembly and disassembly can be critically regulated by the presence of RNA. In this work, we use a chemically-accurate sequence-dependent coarse-grained model for proteins and RNA to unravel the impact of RNA in modulating the transport properties and stability of biomolecular condensates. We explore the phase behavior of several RNA-binding proteins such as FUS, hnRNPA1, and TDP-43 proteins along with that of their corresponding prion-like domains and RNA recognition motifs from absence to moderately high RNA concentration. By characterizing the phase diagram, key molecular interactions, surface tension, and transport properties of the condensates, we report a dual RNA-induced behavior: on the one hand, RNA enhances phase separation at low concentration as long as the RNA radius of gyration is comparable to that of the proteins, whereas at high concentration, it inhibits the ability of proteins to self-assemble independently of its length. On the other hand, along with the stability modulation, the viscosity of the condensates can be considerably reduced at high RNA concentration as long as the length of the RNA chains is shorter than that of the proteins. Conversely, long RNA strands increase viscosity even at high concentration, but barely modify protein self-diffusion which mainly depends on RNA concentration and on the effect RNA has on droplet density. On the whole, our work rationalizes the different routes by which RNA can regulate phase separation and condensate dynamics, as well as the subsequent aberrant rigidification implicated in the emergence of various neuropathologies and age-related diseases.
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Affiliation(s)
- Andrés R Tejedor
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain
| | - Adiran Garaizar
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Jorge Ramírez
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain.
| | - Jorge R Espinosa
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom.
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Tejedor AR, Garaizar A, Ramírez J, Espinosa JR. 'RNA modulation of transport properties and stability in phase-separated condensates. Biophys J 2021; 120:5169-5186. [PMID: 34762868 PMCID: PMC8715277 DOI: 10.1016/j.bpj.2021.11.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/03/2021] [Indexed: 12/29/2022] Open
Abstract
One of the key mechanisms employed by cells to control their spatiotemporal organization is the formation and dissolution of phase-separated condensates. The balance between condensate assembly and disassembly can be critically regulated by the presence of RNA. In this work, we use a chemically-accurate sequence-dependent coarse-grained model for proteins and RNA to unravel the impact of RNA in modulating the transport properties and stability of biomolecular condensates. We explore the phase behavior of several RNA-binding proteins such as FUS, hnRNPA1, and TDP-43 proteins along with that of their corresponding prion-like domains and RNA recognition motifs from absence to moderately high RNA concentration. By characterizing the phase diagram, key molecular interactions, surface tension, and transport properties of the condensates, we report a dual RNA-induced behavior: on the one hand, RNA enhances phase separation at low concentration as long as the RNA radius of gyration is comparable to that of the proteins, whereas at high concentration, it inhibits the ability of proteins to self-assemble independently of its length. On the other hand, along with the stability modulation, the viscosity of the condensates can be considerably reduced at high RNA concentration as long as the length of the RNA chains is shorter than that of the proteins. Conversely, long RNA strands increase viscosity even at high concentration, but barely modify protein self-diffusion which mainly depends on RNA concentration and on the effect RNA has on droplet density. On the whole, our work rationalizes the different routes by which RNA can regulate phase separation and condensate dynamics, as well as the subsequent aberrant rigidification implicated in the emergence of various neuropathologies and age-related diseases.
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Affiliation(s)
- Andrés R Tejedor
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain
| | - Adiran Garaizar
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Jorge Ramírez
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain.
| | - Jorge R Espinosa
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom.
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29
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Tom JK, Deniz AA. Complex dynamics of multicomponent biological coacervates. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101488] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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30
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Lyonnais S, Sadiq SK, Lorca-Oró C, Dufau L, Nieto-Marquez S, Escribà T, Gabrielli N, Tan X, Ouizougun-Oubari M, Okoronkwo J, Reboud-Ravaux M, Gatell JM, Marquet R, Paillart JC, Meyerhans A, Tisné C, Gorelick RJ, Mirambeau G. The HIV-1 Nucleocapsid Regulates Its Own Condensation by Phase-Separated Activity-Enhancing Sequestration of the Viral Protease during Maturation. Viruses 2021; 13:v13112312. [PMID: 34835118 PMCID: PMC8625067 DOI: 10.3390/v13112312] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/09/2021] [Accepted: 11/11/2021] [Indexed: 02/07/2023] Open
Abstract
A growing number of studies indicate that mRNAs and long ncRNAs can affect protein populations by assembling dynamic ribonucleoprotein (RNP) granules. These phase-separated molecular ‘sponges’, stabilized by quinary (transient and weak) interactions, control proteins involved in numerous biological functions. Retroviruses such as HIV-1 form by self-assembly when their genomic RNA (gRNA) traps Gag and GagPol polyprotein precursors. Infectivity requires extracellular budding of the particle followed by maturation, an ordered processing of ∼2400 Gag and ∼120 GagPol by the viral protease (PR). This leads to a condensed gRNA-NCp7 nucleocapsid and a CAp24-self-assembled capsid surrounding the RNP. The choreography by which all of these components dynamically interact during virus maturation is one of the missing milestones to fully depict the HIV life cycle. Here, we describe how HIV-1 has evolved a dynamic RNP granule with successive weak–strong–moderate quinary NC-gRNA networks during the sequential processing of the GagNC domain. We also reveal two palindromic RNA-binding triads on NC, KxxFxxQ and QxxFxxK, that provide quinary NC-gRNA interactions. Consequently, the nucleocapsid complex appears properly aggregated for capsid reassembly and reverse transcription, mandatory processes for viral infectivity. We show that PR is sequestered within this RNP and drives its maturation/condensation within minutes, this process being most effective at the end of budding. We anticipate such findings will stimulate further investigations of quinary interactions and emergent mechanisms in crowded environments throughout the wide and growing array of RNP granules.
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Affiliation(s)
- Sébastien Lyonnais
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
- Centre d’Etudes des Maladies Infectieuses et Pharmacologie Anti-Infectieuse (CEMIPAI), CNRS UAR 3725, Université de Montpellier, 1919 Route de Mende, CEDEX 05, 34293 Montpellier, France
- Correspondence: (S.L.); (S.K.S.); (G.M.)
| | - S. Kashif Sadiq
- Infection Biology Laboratory, Department of Experimental and Health Sciences (DCEXS), Universitat Pompeu Fabra, Carrer Doctor Aiguader 88, 08003 Barcelona, Spain;
- Molecular and Cellular Modeling Group, Heidelberg Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
- Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
- Correspondence: (S.L.); (S.K.S.); (G.M.)
| | - Cristina Lorca-Oró
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
| | - Laure Dufau
- Biological Adaptation and Ageing (B2A), CNRS UMR 8256 & INSERM ERL U1164, Institut de Biologie Paris-Seine (IBPS), Faculté des Sciences et d’Ingénierie (FSI), Sorbonne Université, 7 Quai St Bernard, CEDEX 05, 75252 Paris, France; (L.D.); (M.R.-R.)
| | - Sara Nieto-Marquez
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
| | - Tuixent Escribà
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
| | - Natalia Gabrielli
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
| | - Xiao Tan
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
- Biological Adaptation and Ageing (B2A), CNRS UMR 8256 & INSERM ERL U1164, Institut de Biologie Paris-Seine (IBPS), Faculté des Sciences et d’Ingénierie (FSI), Sorbonne Université, 7 Quai St Bernard, CEDEX 05, 75252 Paris, France; (L.D.); (M.R.-R.)
| | - Mohamed Ouizougun-Oubari
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
| | - Josephine Okoronkwo
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
| | - Michèle Reboud-Ravaux
- Biological Adaptation and Ageing (B2A), CNRS UMR 8256 & INSERM ERL U1164, Institut de Biologie Paris-Seine (IBPS), Faculté des Sciences et d’Ingénierie (FSI), Sorbonne Université, 7 Quai St Bernard, CEDEX 05, 75252 Paris, France; (L.D.); (M.R.-R.)
| | - José Maria Gatell
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
- Facultat de Medicina y Ciencias de la Salud, Universitat de Barcelona, Carrer de Casanova 143, 08036 Barcelona, Spain
| | - Roland Marquet
- Architecture et Réactivité de l’ARN, CNRS UPR 9002, Université de Strasbourg, 2 Allée Conrad Roentgen, 67000 Strasbourg, France; (R.M.); (J.-C.P.)
| | - Jean-Christophe Paillart
- Architecture et Réactivité de l’ARN, CNRS UPR 9002, Université de Strasbourg, 2 Allée Conrad Roentgen, 67000 Strasbourg, France; (R.M.); (J.-C.P.)
| | - Andreas Meyerhans
- Infection Biology Laboratory, Department of Experimental and Health Sciences (DCEXS), Universitat Pompeu Fabra, Carrer Doctor Aiguader 88, 08003 Barcelona, Spain;
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig de Lluís Companys 23, 08010 Barcelona, Spain
| | - Carine Tisné
- Expression Génétique Microbienne, CNRS UMR 8261, Institut de Biologie Physico-Chimique (IBPC), Université de Paris, 13 Rue Pierre et Marie Curie, 75005 Paris, France;
| | - Robert J. Gorelick
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA;
| | - Gilles Mirambeau
- Infectious Disease & AIDS Research Unit, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Villaroel 170, 08036 Barcelona, Spain; (C.L.-O.); (S.N.-M.); (T.E.); (N.G.); (X.T.); (M.O.-O.); (J.O.); (J.M.G.)
- Biologie Intégrative des Organismes Marins (BIOM), CNRS UMR 7232, Observatoire Océanologique de Banyuls (OOB), Faculté des Sciences et d’Ingénierie (FSI), Sorbonne Université, 1 Avenue Pierre Fabre, 66650 Banyuls-sur-Mer, France
- Correspondence: (S.L.); (S.K.S.); (G.M.)
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31
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Garaizar A, Espinosa JR. Salt dependent phase behavior of intrinsically disordered proteins from a coarse-grained model with explicit water and ions. J Chem Phys 2021; 155:125103. [PMID: 34598583 DOI: 10.1063/5.0062687] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Multivalent proteins and nucleic acids can self-assemble into biomolecular condensates that contribute to compartmentalize the cell interior. Computer simulations offer a unique view to elucidate the mechanisms and key intermolecular interactions behind the dynamic formation and dissolution of these condensates. In this work, we present a novel approach to include explicit water and salt in sequence-dependent coarse-grained (CG) models for proteins and RNA, enabling the study of biomolecular condensate formation in a salt-dependent manner. Our framework combines a reparameterized version of the HPS protein force field with the monoatomic mW water model and the mW-ion potential for NaCl. We show how our CG model qualitatively captures the experimental radius of the gyration trend of a subset of intrinsically disordered proteins and reproduces the experimental protein concentration and water percentage of the human fused in sarcoma (FUS) low-complexity-domain droplets at physiological salt concentration. Moreover, we perform seeding simulations as a function of salt concentration for two antagonist systems: the engineered peptide PR25 and poly-uridine/poly-arginine mixtures, finding good agreement with their reported in vitro phase behavior with salt concentration in both cases. Taken together, our work represents a step forward towards extending sequence-dependent CG models to include water and salt, and to consider their key role in biomolecular condensate self-assembly.
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Affiliation(s)
- Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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32
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Loh D, Reiter RJ. Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders. Antioxidants (Basel) 2021; 10:1483. [PMID: 34573116 PMCID: PMC8465482 DOI: 10.3390/antiox10091483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX 78229, USA
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33
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Lichtinger SM, Garaizar A, Collepardo-Guevara R, Reinhardt A. Targeted modulation of protein liquid-liquid phase separation by evolution of amino-acid sequence. PLoS Comput Biol 2021; 17:e1009328. [PMID: 34428231 PMCID: PMC8415608 DOI: 10.1371/journal.pcbi.1009328] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 09/03/2021] [Accepted: 08/07/2021] [Indexed: 12/27/2022] Open
Abstract
Rationally and efficiently modifying the amino-acid sequence of proteins to control their ability to undergo liquid-liquid phase separation (LLPS) on demand is not only highly desirable, but can also help to elucidate which protein features are important for LLPS. Here, we propose a computational method that couples a genetic algorithm to a sequence-dependent coarse-grained protein model to evolve the amino-acid sequences of phase-separating intrinsically disordered protein regions (IDRs), and purposely enhance or inhibit their capacity to phase-separate. We validate the predicted critical solution temperatures of the mutated sequences with ABSINTH, a more accurate all-atom model. We apply the algorithm to the phase-separating IDRs of three naturally occurring proteins, namely FUS, hnRNPA1 and LAF1, as prototypes of regions that exist in cells and undergo homotypic LLPS driven by different types of intermolecular interaction, and we find that the evolution of amino-acid sequences towards enhanced LLPS is driven in these three cases, among other factors, by an increase in the average size of the amino acids. However, the direction of change in the molecular driving forces that enhance LLPS (such as hydrophobicity, aromaticity and charge) depends on the initial amino-acid sequence. Finally, we show that the evolution of amino-acid sequences to modulate LLPS is strongly coupled to the make-up of the medium (e.g. the presence or absence of RNA), which may have significant implications for our understanding of phase separation within the many-component mixtures of biological systems.
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Affiliation(s)
- Simon M. Lichtinger
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Adiran Garaizar
- Department of Physics, Cavendish Laboratory, Maxwell Centre, University of Cambridge, Cambridge, United Kingdom
| | - Rosana Collepardo-Guevara
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
- Department of Physics, Cavendish Laboratory, Maxwell Centre, University of Cambridge, Cambridge, United Kingdom
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Aleks Reinhardt
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
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Sanchez-Burgos I, Joseph JA, Collepardo-Guevara R, Espinosa JR. Size conservation emerges spontaneously in biomolecular condensates formed by scaffolds and surfactant clients. Sci Rep 2021; 11:15241. [PMID: 34315935 PMCID: PMC8316449 DOI: 10.1038/s41598-021-94309-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/06/2021] [Indexed: 02/07/2023] Open
Abstract
Biomolecular condensates are liquid-like membraneless compartments that contribute to the spatiotemporal organization of proteins, RNA, and other biomolecules inside cells. Some membraneless compartments, such as nucleoli, are dispersed as different condensates that do not grow beyond a certain size, or do not present coalescence over time. In this work, using a minimal protein model, we show that phase separation of binary mixtures of scaffolds and low-valency clients that can act as surfactants-i.e., that significantly reduce the droplet surface tension-can yield either a single drop or multiple droplets that conserve their sizes on long timescales (herein 'multidroplet size-conserved' scenario'), depending on the scaffold to client ratio. Our simulations demonstrate that protein connectivity and condensate surface tension regulate the balance between these two scenarios. The multidroplet size-conserved scenario spontaneously arises at increasing surfactant-to-scaffold concentrations, when the interfacial penalty for creating small liquid droplets is sufficiently reduced by the surfactant proteins that are preferentially located at the interface. In contrast, low surfactant-to-scaffold concentrations enable continuous growth and fusion of droplets without restrictions. Overall, our work proposes one thermodynamic mechanism to help rationalize how size-conserved coexisting condensates can persist inside cells-shedding light on the roles of protein connectivity, binding affinity, and droplet composition in this process.
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Affiliation(s)
- Ignacio Sanchez-Burgos
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Jerelle A Joseph
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Department of Genetics, University of Cambridge, Downing Site, Cambridge, CB2 3EH, UK
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
- Department of Genetics, University of Cambridge, Downing Site, Cambridge, CB2 3EH, UK
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
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Iarovaia OV, Ioudinkova ES, Velichko AK, Razin SV. Manipulation of Cellular Processes via Nucleolus Hijaking in the Course of Viral Infection in Mammals. Cells 2021; 10:cells10071597. [PMID: 34202380 PMCID: PMC8303250 DOI: 10.3390/cells10071597] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/22/2021] [Accepted: 06/23/2021] [Indexed: 12/16/2022] Open
Abstract
Due to their exceptional simplicity of organization, viruses rely on the resources, molecular mechanisms, macromolecular complexes, regulatory pathways, and functional compartments of the host cell for an effective infection process. The nucleolus plays an important role in the process of interaction between the virus and the infected cell. The interactions of viral proteins and nucleic acids with the nucleolus during the infection process are universal phenomena and have been described for almost all taxonomic groups. During infection, proteins of the nucleolus in association with viral components can be directly used for the processes of replication and transcription of viral nucleic acids and the assembly and transport of viral particles. In the course of a viral infection, the usurpation of the nucleolus functions occurs and the usurpation is accompanied by profound changes in ribosome biogenesis. Recent studies have demonstrated that the nucleolus is a multifunctional and dynamic compartment. In addition to the biogenesis of ribosomes, it is involved in regulating the cell cycle and apoptosis, responding to cellular stress, repairing DNA, and transcribing RNA polymerase II-dependent genes. A viral infection can be accompanied by targeted transport of viral proteins to the nucleolus, massive release of resident proteins of the nucleolus into the nucleoplasm and cytoplasm, the movement of non-nucleolar proteins into the nucleolar compartment, and the temporary localization of viral nucleic acids in the nucleolus. The interaction of viral and nucleolar proteins interferes with canonical and non-canonical functions of the nucleolus and results in a change in the physiology of the host cell: cell cycle arrest, intensification or arrest of ribosome biogenesis, induction or inhibition of apoptosis, and the modification of signaling cascades involved in the stress response. The nucleolus is, therefore, an important target during viral infection. In this review, we discuss the functional impact of viral proteins and nucleic acid interaction with the nucleolus during infection.
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Vweza AO, Song CG, Chong KT. Liquid-Liquid Phase Separation in the Presence of Macromolecular Crowding and State-dependent Kinetics. Int J Mol Sci 2021; 22:6675. [PMID: 34206440 PMCID: PMC8268629 DOI: 10.3390/ijms22136675] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 12/27/2022] Open
Abstract
Biomolecular condensates formed via liquid-liquid phase separation (LLPS) are increasingly being shown to play major roles in cellular self-organization dynamics in health and disease. It is well established that macromolecular crowding has a profound impact on protein interactions, particularly those that lead to LLPS. Although synthetic crowding agents are used during in vitro LLPS experiments, they are considerably different from the highly crowded nucleo-/cytoplasm and the effects of in vivo crowding remain poorly understood. In this work, we applied computational modeling to investigate the effects of macromolecular crowding on LLPS. To include biologically relevant LLPS dynamics, we extended the conventional Cahn-Hilliard model for phase separation by coupling it to experimentally derived macromolecular crowding dynamics and state-dependent reaction kinetics. Through extensive field-theoretic computer simulations, we show that the inclusion of macromolecular crowding results in late-stage coarsening and the stabilization of relatively smaller condensates. At a high crowding concentration, there is an accelerated growth and late-stage arrest of droplet formation, effectively resulting in anomalous labyrinthine morphologies akin to protein gelation observed in experiments. These results not only elucidate the crowder effects observed in experiments, but also highlight the importance of including state-dependent kinetics in LLPS models, and may help in designing further experiments to probe the intricate roles played by LLPS in self-organization dynamics of cells.
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Affiliation(s)
- Alick-O. Vweza
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju 54896, Korea; (A.-O.V.); (C.-G.S.)
| | - Chul-Gyu Song
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju 54896, Korea; (A.-O.V.); (C.-G.S.)
- Advanced Biomedical Imaging Center, Jeonbuk National University, Jeonju 54896, Korea
| | - Kil-To Chong
- Department of Electronics and Information Engineering, Jeonbuk National University, Jeonju 54896, Korea; (A.-O.V.); (C.-G.S.)
- Advanced Electronics and Information Research Center, Jeonbuk National University, Jeonju 54896, Korea
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37
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On the specificity of protein-protein interactions in the context of disorder. Biochem J 2021; 478:2035-2050. [PMID: 34101805 PMCID: PMC8203207 DOI: 10.1042/bcj20200828] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 02/07/2023]
Abstract
With the increased focus on intrinsically disordered proteins (IDPs) and their large interactomes, the question about their specificity — or more so on their multispecificity — arise. Here we recapitulate how specificity and multispecificity are quantified and address through examples if IDPs in this respect differ from globular proteins. The conclusion is that quantitatively, globular proteins and IDPs are similar when it comes to specificity. However, compared with globular proteins, IDPs have larger interactome sizes, a phenomenon that is further enabled by their flexibility, repetitive binding motifs and propensity to adapt to different binding partners. For IDPs, this adaptability, interactome size and a higher degree of multivalency opens for new interaction mechanisms such as facilitated exchange through trimer formation and ultra-sensitivity via threshold effects and ensemble redistribution. IDPs and their interactions, thus, do not compromise the definition of specificity. Instead, it is the sheer size of their interactomes that complicates its calculation. More importantly, it is this size that challenges how we conceptually envision, interpret and speak about their specificity.
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38
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Joseph JA, Espinosa JR, Sanchez-Burgos I, Garaizar A, Frenkel D, Collepardo-Guevara R. Thermodynamics and kinetics of phase separation of protein-RNA mixtures by a minimal model. Biophys J 2021; 120:1219-1230. [PMID: 33571491 DOI: 10.1016/j.bpj.2021.01.031] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 11/11/2020] [Accepted: 01/20/2021] [Indexed: 12/20/2022] Open
Abstract
Intracellular liquid-liquid phase separation enables the formation of biomolecular condensates, such as ribonucleoprotein granules, which play a crucial role in the spatiotemporal organization of biomolecules (e.g., proteins and RNAs). Here, we introduce a patchy-particle polymer model to investigate liquid-liquid phase separation of protein-RNA mixtures. We demonstrate that at low to moderate concentrations, RNA enhances the stability of RNA-binding protein condensates because it increases the molecular connectivity of the condensed-liquid phase. Importantly, we find that RNA can also accelerate the nucleation stage of phase separation. Additionally, we assess how the capacity of RNA to increase the stability of condensates is modulated by the relative protein-protein/protein-RNA binding strengths. We find that phase separation and multiphase organization of multicomponent condensates is favored when the RNA binds with higher affinity to the lower-valency proteins in the mixture than to the cognate higher-valency proteins. Collectively, our results shed light on the roles of RNA in ribonucleoprotein granule formation and the internal structuring of stress granules.
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Affiliation(s)
- Jerelle A Joseph
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ignacio Sanchez-Burgos
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Adiran Garaizar
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Daan Frenkel
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Rosana Collepardo-Guevara
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
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