1
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Strom AR, Eeftens JM, Polyachenko Y, Weaver CJ, Watanabe HF, Bracha D, Orlovsky ND, Jumper CC, Jacobs WM, Brangwynne CP. Interplay of condensation and chromatin binding underlies BRD4 targeting. Mol Biol Cell 2024; 35:ar88. [PMID: 38656803 DOI: 10.1091/mbc.e24-01-0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
Nuclear compartments form via biomolecular phase separation, mediated through multivalent properties of biomolecules concentrated within condensates. Certain compartments are associated with specific chromatin regions, including transcriptional initiation condensates, which are composed of transcription factors and transcriptional machinery, and form at acetylated regions including enhancer and promoter loci. While protein self-interactions, especially within low-complexity and intrinsically disordered regions, are known to mediate condensation, the role of substrate-binding interactions in regulating the formation and function of biomolecular condensates is underexplored. Here, utilizing live-cell experiments in parallel with coarse-grained simulations, we investigate how chromatin interaction of the transcriptional activator BRD4 modulates its condensate formation. We find that both kinetic and thermodynamic properties of BRD4 condensation are affected by chromatin binding: nucleation rate is sensitive to BRD4-chromatin interactions, providing an explanation for the selective formation of BRD4 condensates at acetylated chromatin regions, and thermodynamically, multivalent acetylated chromatin sites provide a platform for BRD4 clustering below the concentration required for off-chromatin condensation. This provides a molecular and physical explanation of the relationship between nuclear condensates and epigenetically modified chromatin that results in their mutual spatiotemporal regulation, suggesting that epigenetic modulation is an important mechanism by which the cell targets transcriptional condensates to specific chromatin loci.
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Affiliation(s)
- Amy R Strom
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
| | - Jorine M Eeftens
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
- Radboud Institute for Molecular Life Sciences, Radboud University, 6525 XZ Nijmegen, Netherlands
| | - Yury Polyachenko
- Department of Chemistry, Princeton University, Princeton, NJ 08544
| | - Claire J Weaver
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
- Department of Molecular and Cellular Biology, Princeton University, Princeton, NJ 08544
| | | | - Dan Bracha
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
- Department of Biotechnology and Food Engineering, Technion, Haifa 3200, Israel
| | - Natalia D Orlovsky
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
- Biological and Biomedical Sciences Program, Harvard University, Boston, MA 02115
| | - Chanelle C Jumper
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
- Nereid Therapeutics, Boston, MA
| | - William M Jacobs
- Department of Chemistry, Princeton University, Princeton, NJ 08544
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544
- Omenn-Darling Bioengineering Institute, Princeton University, Princeton, NJ 08544
- Howard Hughes Medical Institute, Chevy Chase, MD 20815
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2
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Vos BE, Muenker TM, Betz T. Characterizing intracellular mechanics via optical tweezers-based microrheology. Curr Opin Cell Biol 2024; 88:102374. [PMID: 38824902 DOI: 10.1016/j.ceb.2024.102374] [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: 11/30/2023] [Revised: 04/24/2024] [Accepted: 05/03/2024] [Indexed: 06/04/2024]
Abstract
Intracellular organization is a highly regulated homeostatic state maintained to ensure eukaryotic cells' correct and efficient functioning. Thanks to decades of research, vast knowledge of the proteins involved in intracellular transport and organization has been acquired. However, how these influence and potentially regulate the intracellular mechanical properties of the cell is largely unknown. There is a deep knowledge gap between the understanding of cortical mechanics, which is accessible by a series of experimental tools, and the intracellular situation that has been largely neglected due to the difficulty of performing intracellular mechanics measurements. Recently, tools required for such quantitative and localized analysis of intracellular mechanics have been introduced. Here, we review how these approaches and the resulting viscoelastic models lead the way to a full mechanical description of the cytoplasm, which is instrumental for a quantitative characterization of the intracellular life of cells.
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Affiliation(s)
- Bart E Vos
- Third Institute of Physics, Georg August University, Göttingen, Germany
| | - Till M Muenker
- Third Institute of Physics, Georg August University, Göttingen, Germany
| | - Timo Betz
- Third Institute of Physics, Georg August University, Göttingen, Germany; Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), Georg August University, Göttingen, Germany.
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3
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Naz M, Zhang L, Chen C, Yang S, Dou H, Mann S, Li J. Self-assembly of stabilized droplets from liquid-liquid phase separation for higher-order structures and functions. Commun Chem 2024; 7:79. [PMID: 38594355 PMCID: PMC11004187 DOI: 10.1038/s42004-024-01168-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 04/03/2024] [Indexed: 04/11/2024] Open
Abstract
Dynamic microscale droplets produced by liquid-liquid phase separation (LLPS) have emerged as appealing biomaterials due to their remarkable features. However, the instability of droplets limits the construction of population-level structures with collective behaviors. Here we first provide a brief background of droplets in the context of materials properties. Subsequently, we discuss current strategies for stabilizing droplets including physical separation and chemical modulation. We also discuss the recent development of LLPS droplets for various applications such as synthetic cells and biomedical materials. Finally, we give insights on how stabilized droplets can self-assemble into higher-order structures displaying coordinated functions to fully exploit their potentials in bottom-up synthetic biology and biomedical applications.
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Affiliation(s)
- Mehwish Naz
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Zhangjiang Institute for Advanced Study (ZIAS), Shanghai Jiao Tong University, 429 Zhangheng Road, Shanghai, 201203, China
| | - Lin Zhang
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
- Zhangjiang Institute for Advanced Study (ZIAS), Shanghai Jiao Tong University, 429 Zhangheng Road, Shanghai, 201203, China
| | - Chong Chen
- MediCity Research Laboratory, University of Turku, Tykistökatu 6, Turku, 20520, Finland
| | - Shuo Yang
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Zhangjiang Institute for Advanced Study (ZIAS), Shanghai Jiao Tong University, 429 Zhangheng Road, Shanghai, 201203, China.
| | - Hongjing Dou
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Zhangjiang Institute for Advanced Study (ZIAS), Shanghai Jiao Tong University, 429 Zhangheng Road, Shanghai, 201203, China.
| | - Stephen Mann
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Zhangjiang Institute for Advanced Study (ZIAS), Shanghai Jiao Tong University, 429 Zhangheng Road, Shanghai, 201203, China.
- Centre for Protolife Research and Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, UK.
- Max Planck-Bristol Centre for Minimal Biology, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK.
| | - Jianwei Li
- MediCity Research Laboratory, University of Turku, Tykistökatu 6, Turku, 20520, Finland.
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4
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Spegg V, Altmeyer M. Genome maintenance meets mechanobiology. Chromosoma 2024; 133:15-36. [PMID: 37581649 PMCID: PMC10904543 DOI: 10.1007/s00412-023-00807-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/20/2023] [Accepted: 07/26/2023] [Indexed: 08/16/2023]
Abstract
Genome stability is key for healthy cells in healthy organisms, and deregulated maintenance of genome integrity is a hallmark of aging and of age-associated diseases including cancer and neurodegeneration. To maintain a stable genome, genome surveillance and repair pathways are closely intertwined with cell cycle regulation and with DNA transactions that occur during transcription and DNA replication. Coordination of these processes across different time and length scales involves dynamic changes of chromatin topology, clustering of fragile genomic regions and repair factors into nuclear repair centers, mobilization of the nuclear cytoskeleton, and activation of cell cycle checkpoints. Here, we provide a general overview of cell cycle regulation and of the processes involved in genome duplication in human cells, followed by an introduction to replication stress and to the cellular responses elicited by perturbed DNA synthesis. We discuss fragile genomic regions that experience high levels of replication stress, with a particular focus on telomere fragility caused by replication stress at the ends of linear chromosomes. Using alternative lengthening of telomeres (ALT) in cancer cells and ALT-associated PML bodies (APBs) as examples of replication stress-associated clustered DNA damage, we discuss compartmentalization of DNA repair reactions and the role of protein properties implicated in phase separation. Finally, we highlight emerging connections between DNA repair and mechanobiology and discuss how biomolecular condensates, components of the nuclear cytoskeleton, and interfaces between membrane-bound organelles and membraneless macromolecular condensates may cooperate to coordinate genome maintenance in space and time.
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Affiliation(s)
- Vincent Spegg
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.
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5
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Voß Y, Klaus S, Lichti NP, Ganter M, Guizetti J. Malaria parasite centrins can assemble by Ca2+-inducible condensation. PLoS Pathog 2023; 19:e1011899. [PMID: 38150475 PMCID: PMC10775985 DOI: 10.1371/journal.ppat.1011899] [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: 10/08/2023] [Revised: 01/09/2024] [Accepted: 12/13/2023] [Indexed: 12/29/2023] Open
Abstract
Centrins are small calcium-binding proteins that have a variety of roles and are universally associated with eukaryotic centrosomes. Rapid proliferation of the malaria-causing parasite Plasmodium falciparum in the human blood depends on a particularly divergent and acentriolar centrosome, which incorporates several essential centrins. Their precise mode of action, however, remains unclear. In this study calcium-inducible liquid-liquid phase separation is revealed as an evolutionarily conserved principle of assembly for multiple centrins from P. falciparum and other species. Furthermore, the disordered N-terminus and calcium-binding motifs are defined as essential features for reversible biomolecular condensation, and we demonstrate that certain centrins can form co-condensates. In vivo analysis using live cell STED microscopy shows liquid-like dynamics of centrosomal centrin. Additionally, implementation of an inducible protein overexpression system reveals concentration-dependent formation of extra-centrosomal centrin assemblies with condensate-like properties. The timing of foci formation and dissolution suggests that centrin assembly is regulated. This study thereby provides a new model for centrin accumulation at eukaryotic centrosomes.
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Affiliation(s)
- Yannik Voß
- Center for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
- German Center for Infection Research, partner site Heidelberg, Heidelberg, Germany
| | - Severina Klaus
- Center for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
- Department of Infectious Diseases, Virology, Heidelberg University Hospital, Heidelberg, Germany
| | - Nicolas P. Lichti
- Center for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Markus Ganter
- Center for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Julien Guizetti
- Center for Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
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6
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Lawrence EJ, Chatterjee S, Zanic M. More is different: Reconstituting complexity in microtubule regulation. J Biol Chem 2023; 299:105398. [PMID: 37898404 PMCID: PMC10694663 DOI: 10.1016/j.jbc.2023.105398] [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: 06/11/2023] [Revised: 10/13/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023] Open
Abstract
Microtubules are dynamic cytoskeletal filaments that undergo stochastic switching between phases of polymerization and depolymerization-a behavior known as dynamic instability. Many important cellular processes, including cell motility, chromosome segregation, and intracellular transport, require complex spatiotemporal regulation of microtubule dynamics. This coordinated regulation is achieved through the interactions of numerous microtubule-associated proteins (MAPs) with microtubule ends and lattices. Here, we review the recent advances in our understanding of microtubule regulation, focusing on results arising from biochemical in vitro reconstitution approaches using purified multiprotein ensembles. We discuss how the combinatory effects of MAPs affect both the dynamics of individual microtubule ends, as well as the stability and turnover of the microtubule lattice. In addition, we highlight new results demonstrating the roles of protein condensates in microtubule regulation. Our overall intent is to showcase how lessons learned from reconstitution approaches help unravel the regulatory mechanisms at play in complex cellular environments.
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Affiliation(s)
- Elizabeth J Lawrence
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Saptarshi Chatterjee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee, USA; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA.
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7
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Tayar AM, Caballero F, Anderberg T, Saleh OA, Cristina Marchetti M, Dogic Z. Controlling liquid-liquid phase behaviour with an active fluid. NATURE MATERIALS 2023; 22:1401-1408. [PMID: 37679525 DOI: 10.1038/s41563-023-01660-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 08/02/2023] [Indexed: 09/09/2023]
Abstract
Demixing binary liquids is a ubiquitous transition explained using a well-established thermodynamic formalism that requires the equality of intensive thermodynamics parameters across phase boundaries. Demixing transitions also occur when binary fluid mixtures are driven away from equilibrium, but predicting and designing such out-of-equilibrium transitions remains a challenge. Here we study the liquid-liquid phase separation of attractive DNA nanostars driven away from equilibrium using a microtubule-based active fluid. We find that activity lowers the critical temperature and narrows the range of coexistence concentrations, but only in the presence of mechanical bonds between the liquid droplets and reconfiguring active fluid. Similar behaviours are observed in numerical simulations, suggesting that the activity suppression of the critical point is a generic feature of active liquid-liquid phase separation. Our work describes a versatile platform for building soft active materials with feedback control and providing an insight into self-organization in cell biology.
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Affiliation(s)
- Alexandra M Tayar
- Department of Physics, University of California, Santa Barbara, CA, USA.
| | | | - Trevor Anderberg
- Department of Physics, University of California, Santa Barbara, CA, USA
| | - Omar A Saleh
- Department of Physics, University of California, Santa Barbara, CA, USA
- Materials Department, University of California, Santa Barbara, CA, USA
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
| | - M Cristina Marchetti
- Department of Physics, University of California, Santa Barbara, CA, USA
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA
| | - Zvonimir Dogic
- Department of Physics, University of California, Santa Barbara, CA, USA.
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, USA.
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8
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Cochard A, Safieddine A, Combe P, Benassy M, Weil D, Gueroui Z. Condensate functionalization with microtubule motors directs their nucleation in space and allows manipulating RNA localization. EMBO J 2023; 42:e114106. [PMID: 37724036 PMCID: PMC10577640 DOI: 10.15252/embj.2023114106] [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: 03/23/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/20/2023] Open
Abstract
The localization of RNAs in cells is critical for many cellular processes. Whereas motor-driven transport of ribonucleoprotein (RNP) condensates plays a prominent role in RNA localization in cells, their study remains limited by the scarcity of available tools allowing to manipulate condensates in a spatial manner. To fill this gap, we reconstitute in cellula a minimal RNP transport system based on bioengineered condensates, which were functionalized with kinesins and dynein-like motors, allowing for their positioning at either the cell periphery or centrosomes. This targeting mostly occurs through the active transport of the condensate scaffolds, which leads to localized nucleation of phase-separated condensates. Then, programming the condensates to recruit specific mRNAs is able to shift the localization of these mRNAs toward the cell periphery or the centrosomes. Our method opens novel perspectives for examining the role of RNA localization as a driver of cellular functions.
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Affiliation(s)
- Audrey Cochard
- Department of Chemistry, École Normale SupérieurePSL University, Sorbonne Université, CNRSParisFrance
- Sorbonne Université, CNRS, Institut de Biologie Paris‐Seine (IBPS), Laboratoire de Biologie du DéveloppementParisFrance
| | - Adham Safieddine
- Sorbonne Université, CNRS, Institut de Biologie Paris‐Seine (IBPS), Laboratoire de Biologie du DéveloppementParisFrance
| | - Pauline Combe
- Department of Chemistry, École Normale SupérieurePSL University, Sorbonne Université, CNRSParisFrance
| | - Marie‐Noëlle Benassy
- Sorbonne Université, CNRS, Institut de Biologie Paris‐Seine (IBPS), Laboratoire de Biologie du DéveloppementParisFrance
| | - Dominique Weil
- Sorbonne Université, CNRS, Institut de Biologie Paris‐Seine (IBPS), Laboratoire de Biologie du DéveloppementParisFrance
| | - Zoher Gueroui
- Department of Chemistry, École Normale SupérieurePSL University, Sorbonne Université, CNRSParisFrance
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9
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Liu JX, Haataja MP, Košmrlj A, Datta SS, Arnold CB, Priestley RD. Liquid-liquid phase separation within fibrillar networks. Nat Commun 2023; 14:6085. [PMID: 37770446 PMCID: PMC10539382 DOI: 10.1038/s41467-023-41528-8] [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: 02/14/2023] [Accepted: 09/06/2023] [Indexed: 09/30/2023] Open
Abstract
Complex fibrillar networks mediate liquid-liquid phase separation of biomolecular condensates within the cell. Mechanical interactions between these condensates and the surrounding networks are increasingly implicated in the physiology of the condensates and yet, the physical principles underlying phase separation within intracellular media remain poorly understood. Here, we elucidate the dynamics and mechanics of liquid-liquid phase separation within fibrillar networks by condensing oil droplets within biopolymer gels. We find that condensates constrained within the network pore space grow in abrupt temporal bursts. The subsequent restructuring of condensates and concomitant network deformation is contingent on the fracture of network fibrils, which is determined by a competition between condensate capillarity and network strength. As a synthetic analog to intracellular phase separation, these results further our understanding of the mechanical interactions between biomolecular condensates and fibrillar networks in the cell.
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Affiliation(s)
- Jason X Liu
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08544, USA
| | - Mikko P Haataja
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08544, USA
| | - Andrej Košmrlj
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08544, USA
| | - Sujit S Datta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - Craig B Arnold
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08544, USA
| | - Rodney D Priestley
- Princeton Materials Institute, Princeton University, Princeton, NJ, 08544, USA.
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, 08544, USA.
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10
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Wilby EL, Weil TT. Relating the Biogenesis and Function of P Bodies in Drosophila to Human Disease. Genes (Basel) 2023; 14:1675. [PMID: 37761815 PMCID: PMC10530015 DOI: 10.3390/genes14091675] [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: 07/31/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Drosophila has been a premier model organism for over a century and many discoveries in flies have furthered our understanding of human disease. Flies have been successfully applied to many aspects of health-based research spanning from behavioural addiction, to dysplasia, to RNA dysregulation and protein misfolding. Recently, Drosophila tissues have been used to study biomolecular condensates and their role in multicellular systems. Identified in a wide range of plant and animal species, biomolecular condensates are dynamic, non-membrane-bound sub-compartments that have been observed and characterised in the cytoplasm and nuclei of many cell types. Condensate biology has exciting research prospects because of their diverse roles within cells, links to disease, and potential for therapeutics. In this review, we will discuss processing bodies (P bodies), a conserved biomolecular condensate, with a particular interest in how Drosophila can be applied to advance our understanding of condensate biogenesis and their role in disease.
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Affiliation(s)
| | - Timothy T. Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK;
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11
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Sahu S, Chauhan P, Lumen E, Moody K, Peddireddy K, Mani N, Subramanian R, Robertson-Anderson R, Wolfe AJ, Ross JL. Interplay of self-organization of microtubule asters and crosslinking protein condensates. PNAS NEXUS 2023; 2:pgad231. [PMID: 37497046 PMCID: PMC10367440 DOI: 10.1093/pnasnexus/pgad231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 06/28/2023] [Accepted: 07/03/2023] [Indexed: 07/28/2023]
Abstract
The cytoskeleton is a major focus of physical studies to understand organization inside cells given its primary role in cell motility, cell division, and cell mechanics. Recently, protein condensation has been shown to be another major intracellular organizational strategy. Here, we report that the microtubule crosslinking proteins, MAP65-1 and PRC1, can form phase separated condensates at physiological salt and temperature without additional crowding agents in vitro. The size of the droplets depends on the concentration of protein. MAP65 condensates are liquid at first and can gelate over time. We show that these condensates can nucleate and grow microtubule bundles that form asters, regardless of the viscoelasticity of the condensate. The droplet size directly controls the number of projections in the microtubule asters, demonstrating that the MAP65 concentration can control the organization of microtubules. When gel-like droplets nucleate and grow asters from a shell of tubulin at the surface, the microtubules are able to re-fluidize the MAP65 condensate, returning the MAP65 molecules to solution. This work implies that there is an interplay between condensate formation from microtubule-associated proteins, microtubule organization, and condensate dissolution that could be important for the dynamics of intracellular organization.
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Affiliation(s)
- Sumon Sahu
- Physics Department, Syracuse University, Syracuse, NY 13244, USA
- Department of Physics, New York University, New York, NY 10003, USA
| | - Prashali Chauhan
- Physics Department, Syracuse University, Syracuse, NY 13244, USA
- The Bioinspired Institute, Syracuse University, Syracuse, NY 13244, USA
| | - Ellie Lumen
- Ichor Life Sciences, Inc., 2561 US Route 11, LaFayette, NY 13084, USA
| | - Kelsey Moody
- The Bioinspired Institute, Syracuse University, Syracuse, NY 13244, USA
- Ichor Life Sciences, Inc., 2561 US Route 11, LaFayette, NY 13084, USA
- Lewis School of Health Sciences, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA
| | | | - Nandini Mani
- Massachusetts General Hospital, Boston, MA 02115, USA
| | | | | | - Aaron J Wolfe
- The Bioinspired Institute, Syracuse University, Syracuse, NY 13244, USA
- Ichor Life Sciences, Inc., 2561 US Route 11, LaFayette, NY 13084, USA
- Lewis School of Health Sciences, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA
| | - Jennifer L Ross
- Physics Department, Syracuse University, Syracuse, NY 13244, USA
- The Bioinspired Institute, Syracuse University, Syracuse, NY 13244, USA
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12
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Ramm B, Schumacher D, Harms A, Heermann T, Klos P, Müller F, Schwille P, Søgaard-Andersen L. Biomolecular condensate drives polymerization and bundling of the bacterial tubulin FtsZ to regulate cell division. Nat Commun 2023; 14:3825. [PMID: 37380708 DOI: 10.1038/s41467-023-39513-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 06/07/2023] [Indexed: 06/30/2023] Open
Abstract
Cell division is spatiotemporally precisely regulated, but the underlying mechanisms are incompletely understood. In the social bacterium Myxococcus xanthus, the PomX/PomY/PomZ proteins form a single megadalton-sized complex that directly positions and stimulates cytokinetic ring formation by the tubulin homolog FtsZ. Here, we study the structure and mechanism of this complex in vitro and in vivo. We demonstrate that PomY forms liquid-like biomolecular condensates by phase separation, while PomX self-assembles into filaments generating a single large cellular structure. The PomX structure enriches PomY, thereby guaranteeing the formation of precisely one PomY condensate per cell through surface-assisted condensation. In vitro, PomY condensates selectively enrich FtsZ and nucleate GTP-dependent FtsZ polymerization and bundle FtsZ filaments, suggesting a cell division site positioning mechanism in which the single PomY condensate enriches FtsZ to guide FtsZ-ring formation and division. This mechanism shares features with microtubule nucleation by biomolecular condensates in eukaryotes, supporting this mechanism's ancient origin.
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Affiliation(s)
- Beatrice Ramm
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.
- Department of Physics, Princeton University, Princeton, NJ, 08544, USA.
| | - Dominik Schumacher
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany.
| | - Andrea Harms
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany
| | - Tamara Heermann
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Philipp Klos
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany
| | - Franziska Müller
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany.
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13
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Law JO, Jones CM, Stevenson T, Williamson TA, Turner MS, Kusumaatmaja H, Grellscheid SN. A bending rigidity parameter for stress granule condensates. SCIENCE ADVANCES 2023; 9:eadg0432. [PMID: 37196085 DOI: 10.1126/sciadv.adg0432] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 04/12/2023] [Indexed: 05/19/2023]
Abstract
Interfacial tension plays an important role in governing the dynamics of droplet coalescence and determining how condensates interact with and deform lipid membranes and biological filaments. We demonstrate that an interfacial tension-only model is inadequate for describing stress granules in live cells. Harnessing a high-throughput flicker spectroscopy pipeline to analyze the shape fluctuations of tens of thousands of stress granules, we find that the measured fluctuation spectra require an additional contribution, which we attribute to elastic bending deformation. We also show that stress granules have an irregular, nonspherical base shape. These results suggest that stress granules are viscoelastic droplets with a structured interface, rather than simple Newtonian liquids. Furthermore, we observe that the measured interfacial tensions and bending rigidities span a range of several orders of magnitude. Hence, different types of stress granules (and more generally, other biomolecular condensates) can only be differentiated via large-scale surveys.
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Affiliation(s)
- Jack O Law
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Carl M Jones
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
- Department of Biosciences, University of Durham, Durham, UK
| | - Thomas Stevenson
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
| | | | | | | | - Sushma N Grellscheid
- Computational Biology Unit and Department of Biological Sciences, University of Bergen, Bergen, Norway
- Department of Biosciences, University of Durham, Durham, UK
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14
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Yon WJ, Tran JR, Ha T, Zheng Y, Pedersen RT. BuGZ exhibits guanine nucleotide exchange factor activity toward tubulin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.09.539990. [PMID: 37214866 PMCID: PMC10197657 DOI: 10.1101/2023.05.09.539990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
α- and β-tubulin form heterodimers, with GTPase activity, that assemble into microtubules. Like other GTPases, the nucleotide-bound state of tubulin heterodimers controls whether the molecules are in a biologically active or inactive state. While α-tubulin in the heterodimer is constitutively bound to GTP, β-tubulin can be bound to either GDP (GDP-tubulin) or GTP (GTP-tubulin). GTP-tubulin hydrolyzes its GTP to GDP following assembly into a microtubule and, upon disassembly, must exchange its bound GDP for GTP to participate in subsequent microtubule polymerization. Tubulin dimers have been shown to exhibit rapid intrinsic nucleotide exchange in vitro, leading to a commonly accepted belief that a tubulin guanine nucleotide exchange factor (GEF) may be unnecessary in cells. Here, we use quantitative binding assays to show that BuGZ, a spindle assembly factor, binds tightly to GDP-tubulin, less tightly to GTP-tubulin, and weakly to microtubules. We further show that BuGZ promotes the incorporation of GTP into tubulin using a nucleotide exchange assay. The discovery of a tubulin GEF suggests a mechanism that may aid rapid microtubule assembly dynamics in cells.
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Affiliation(s)
- Wesley J. Yon
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Joseph R. Tran
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
| | - Taekjip Ha
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Baltimore, MD, USA
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
| | - Ross T.A. Pedersen
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
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15
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Biomolecular condensation involving the cytoskeleton. Brain Res Bull 2023; 194:105-117. [PMID: 36690162 DOI: 10.1016/j.brainresbull.2023.01.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/07/2023] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Biomolecular condensation of proteins contributes to the organization of the cytoplasm and nucleoplasm. A number of condensation processes appear to be directly involved in regulating the structure, function and dynamics of the cytoskeleton. Liquid-liquid phase separation of cytoskeleton proteins, together with polymerization modulators, promotes cytoskeletal fiber nucleation and branching. Furthermore, the attachment of protein condensates to the cytoskeleton can contribute to cytoskeleton stability and organization, regulate transport, create patterns of functional reaction containers, and connect the cytoskeleton with membranes. Surface-bound condensates can exert and buffer mechanical forces that give stability and flexibility to the cytoskeleton, thus, may play a large role in cell biology. In this review, we introduce the concept and role of cellular biomolecular condensation, explain its special function on cytoskeletal fiber surfaces, and point out potential definition and experimental caveats. We review the current literature on protein condensation processes related to the actin, tubulin, and intermediate filament cytoskeleton, and discuss some of them in the context of neurobiology. In summary, we provide an overview about biomolecular condensation in relation to cytoskeleton structure and function, which offers a base for the exploration and interpretation of cytoskeletal condensates in neurobiology.
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16
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Mondal S, Baumgart T. Membrane reshaping by protein condensates. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184121. [PMID: 36642341 PMCID: PMC10208392 DOI: 10.1016/j.bbamem.2023.184121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 01/15/2023]
Abstract
Proteins can organize into dynamic, functionally important assemblies on fluid membrane surfaces. Phase separation has emerged as an important mechanism for forming such protein assemblies on the membrane during cell signaling, endocytosis, and cytoskeleton regulation. Protein-protein phase separation thus adds novel fluid mosaics to the classical Singer and Nicolson model. Protein condensates formed in this process can modulate membrane morphologies. This is evident from recent reports of protein condensate-driven membrane reshaping in processes such as endocytosis, autophagosome formation, and protein storage vacuole morphogenesis in plants. Lateral phase separation (on the membrane surface) of peripheral curvature coupling proteins can modulate such membrane morphological transitions. Additionally, three-dimensional protein phase separation can result in droplets that through adhesion can affect membrane shape changes. How do these condensate-driven curvature generation mechanisms contrast with the classically recognized scaffolding and amphipathic helix insertion activities of specific membrane remodeling proteins? A salient feature of these condensate-driven membrane activities is that they depend upon both macroscopic features (such as interfacial energies of the condensate, membrane, and cytosol) as well as microscopic, molecular-level interactions (such as protein-lipid binding). This review highlights the current understanding of the mechanisms underlying curvature generation by protein condensates in various biological pathways.
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Affiliation(s)
- Samsuzzoha Mondal
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States.
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, United States.
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17
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Povarova OI, Antifeeva IA, Fonin AV, Turoverov KK, Kuznetsova IM. The Role of Liquid-Liquid Phase Separation in Actin Polymerization. Int J Mol Sci 2023; 24:ijms24043281. [PMID: 36834689 PMCID: PMC9961026 DOI: 10.3390/ijms24043281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/10/2023] Open
Abstract
To date, it has been shown that the phenomenon of liquid-liquid phase separation (LLPS) underlies many seemingly completely different cellular processes. This provided a new idea of the spatiotemporal organization of the cell. The new paradigm makes it possible to provide answers to many long-standing, but still unresolved questions facing the researcher. In particular, spatiotemporal regulation of the assembly/disassembly of the cytoskeleton, including the formation of actin filaments, becomes clearer. To date, it has been shown that coacervates of actin-binding proteins that arise during the phase separation of the liquid-liquid type can integrate G-actin and thereby increase its concentration to initiate polymerization. It has also been shown that the activity intensification of actin-binding proteins that control actin polymerization, such as N-WASP and Arp2/3, can be caused by their integration into liquid droplet coacervates formed by signaling proteins on the inner side of the cell membrane.
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18
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Abstract
Liquid-liquid phase separation (LLPS) underlies the formation of intracellular membraneless compartments in biology and may have played a role in the formation of protocells that concentrate key chemicals during the origins of life. While LLPS of simple systems, such as oil and water, is well understood, many aspects of LLPS in complex, out-of-equilibrium molecular systems remain elusive. Here, the author discusses open questions and recent insights related to the formation, function and fate of such condensates both in cell biology and protocell research.
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19
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Liquid-liquid Phase Separation of α-Synuclein: A New Mechanistic Insight for α-Synuclein Aggregation Associated with Parkinson's Disease Pathogenesis. J Mol Biol 2023; 435:167713. [PMID: 35787838 DOI: 10.1016/j.jmb.2022.167713] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 02/04/2023]
Abstract
Aberrant aggregation of the misfolded presynaptic protein, α-Synuclein (α-Syn) into Lewy body (LB) and Lewy neuritis (LN) is a major pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. Numerous studies have suggested that prefibrillar and fibrillar species of the misfolded α-Syn aggregates are responsible for cell death in PD pathogenesis. However, the precise molecular events during α-Syn aggregation, especially in the early stages, remain elusive. Emerging evidence has demonstrated that liquid-liquid phase separation (LLPS) of α-Syn occurs in the nucleation step of α-Syn aggregation, which offers an alternate non-canonical aggregation pathway in the crowded microenvironment. The liquid-like α-Syn droplets gradually undergo an irreversible liquid-to-solid phase transition into amyloid-like hydrogel entrapping oligomers and fibrils. This new mechanism of α-Syn LLPS and gel formation might represent the molecular basis of cellular toxicity associated with PD. This review aims to demonstrate the recent development of α-Syn LLPS, the underlying mechanism along with the microscopic events of aberrant phase transition. This review further discusses how several intrinsic and extrinsic factors regulate the thermodynamics and kinetics of α-Syn LLPS and co-LLPS with other proteins, which might explain the pathophysiology of α-Syn in various neurodegenerative diseases.
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20
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Kulkarni A, Vidal-Henriquez E, Zwicker D. Effective simulations of interacting active droplets. Sci Rep 2023; 13:733. [PMID: 36639416 PMCID: PMC9839783 DOI: 10.1038/s41598-023-27630-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 01/04/2023] [Indexed: 01/15/2023] Open
Abstract
Droplets form a cornerstone of the spatiotemporal organization of biomolecules in cells. These droplets are controlled using physical processes like chemical reactions and imposed gradients, which are costly to simulate using traditional approaches, like solving the Cahn-Hilliard equation. To overcome this challenge, we here present an alternative, efficient method. The main idea is to focus on the relevant degrees of freedom, like droplet positions and sizes. We derive dynamical equations for these quantities using approximate analytical solutions obtained from a sharp interface limit and linearized equations in the bulk phases. We verify our method against fully-resolved simulations and show that it can describe interacting droplets under the influence of chemical reactions and external gradients using only a fraction of the computational costs of traditional methods. Our method can be extended to include other processes in the future and will thus serve as a relevant platform for understanding the dynamics of droplets in cells.
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Affiliation(s)
- Ajinkya Kulkarni
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077, Göttingen, Germany
| | | | - David Zwicker
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077, Göttingen, Germany.
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21
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Pönisch W, Michaels TCT, Weber CA. Aggregation controlled by condensate rheology. Biophys J 2023; 122:197-214. [PMID: 36369755 PMCID: PMC9822804 DOI: 10.1016/j.bpj.2022.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 06/12/2022] [Accepted: 11/04/2022] [Indexed: 11/13/2022] Open
Abstract
Biomolecular condensates in living cells can exhibit a complex rheology, including viscoelastic and glassy behavior. This rheological behavior of condensates was suggested to regulate polymerization of cytoskeletal filaments and aggregation of amyloid fibrils. Here, we theoretically investigate how the rheological properties of condensates can control the formation of linear aggregates. To this end, we propose a kinetic theory for linear aggregation in coexisting phases, which accounts for the aggregate size distribution and the exchange of aggregates between inside and outside of condensates. The rheology of condensates is accounted in our model via aggregate mobilities that depend on aggregate size. We show that condensate rheology determines whether aggregates of all sizes or dominantly small aggregates are exchanged between condensate inside and outside on the timescale of aggregation. As a result, the ratio of aggregate numbers inside to outside of condensates differs significantly. Strikingly, we also find that weak variations in the rheological properties of condensates can lead to a switch-like change of the number of aggregates. These results suggest a possible physical mechanism for how living cells could control linear aggregation in a switch-like fashion through variations in condensate rheology.
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Affiliation(s)
- Wolfram Pönisch
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Thomas C T Michaels
- Laboratory for Molecular Cell Biology, University College London, London, United Kingdom; Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, United Kingdom; Department of Biology, Institute of Biochemistry, ETH Zurich, Zurich, Switzerland.
| | - Christoph A Weber
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany; Center for Systems Biology Dresden, Dresden, Germany; Faculty of Mathematics, Natural Sciences, and Materials Engineering, Institute of Physics, University of Augsburg, Augsburg, Germany.
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22
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+TIPs condense on microtubule plus-ends. Nat Cell Biol 2023; 25:12-14. [PMID: 36650376 DOI: 10.1038/s41556-022-01068-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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23
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Konietzny A, Wegmann S, Mikhaylova M. The endoplasmic reticulum puts a new spin on synaptic tagging. Trends Neurosci 2023; 46:32-44. [PMID: 36428191 DOI: 10.1016/j.tins.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/12/2022] [Accepted: 10/31/2022] [Indexed: 11/23/2022]
Abstract
The heterogeneity of the endoplasmic reticulum (ER) makes it a versatile platform for a broad range of homeostatic processes, ranging from calcium regulation to synthesis and trafficking of proteins and lipids. It is not surprising that neurons use this organelle to fine-tune synaptic properties and thereby provide specificity to synaptic inputs. In this review, we discuss the mechanisms that enable activity-dependent ER recruitment into dendritic spines, with a focus on molecular mechanisms that mediate transport and retention of the ER in spines. The role of calcium signaling in spine ER, synaptopodin 'tagging' of active synapses, and the formation of the spine apparatus (SA) are highlighted. Finally, we discuss the role of liquid-liquid phase separation as a possible driving force in these processes.
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Affiliation(s)
- Anja Konietzny
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany; Guest Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Susanne Wegmann
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Marina Mikhaylova
- AG Optobiology, Institute of Biology, Humboldt Universität zu Berlin, Berlin, Germany; Guest Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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24
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Wilkinson MD, Ferreira JL, Beeby M, Baum J, Willison KR. The malaria parasite chaperonin containing TCP-1 (CCT) complex: Data integration with other CCT proteomes. Front Mol Biosci 2022; 9:1057232. [PMID: 36567946 PMCID: PMC9772883 DOI: 10.3389/fmolb.2022.1057232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/18/2022] [Indexed: 12/13/2022] Open
Abstract
The multi-subunit chaperonin containing TCP-1 (CCT) is an essential molecular chaperone that functions in the folding of key cellular proteins. This paper reviews the interactome of the eukaryotic chaperonin CCT and its primary clients, the ubiquitous cytoskeletal proteins, actin and tubulin. CCT interacts with other nascent proteins, especially the WD40 propeller proteins, and also assists in the assembly of several protein complexes. A new proteomic dataset is presented for CCT purified from the human malarial parasite, P. falciparum (PfCCT). The CCT8 subunit gene was C-terminally FLAG-tagged using Selection Linked Integration (SLI) and CCT complexes were extracted from infected human erythrocyte cultures synchronized for maximum expression levels of CCT at the trophozoite stage of the parasite's asexual life cycle. We analyze the new PfCCT proteome and incorporate it into our existing model of the CCT system, supported by accumulated data from biochemical and cell biological experiments in many eukaryotic species. Together with measurements of CCT mRNA, CCT protein subunit copy number and the post-translational and chemical modifications of the CCT subunits themselves, a cumulative picture is emerging of an essential molecular chaperone system sitting at the heart of eukaryotic cell growth control and cell cycle regulation.
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Affiliation(s)
- Mark D. Wilkinson
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Josie L. Ferreira
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Morgan Beeby
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Jake Baum
- Department of Life Sciences, Imperial College London, London, United Kingdom,School of Biomedical Sciences, University of New South Wales, Kensington, NSW, Australia
| | - Keith R. Willison
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, United Kingdom,*Correspondence: Keith R. Willison,
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25
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Qian ZG, Huang SC, Xia XX. Synthetic protein condensates for cellular and metabolic engineering. Nat Chem Biol 2022; 18:1330-1340. [DOI: 10.1038/s41589-022-01203-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 10/07/2022] [Indexed: 11/20/2022]
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26
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Mukherjee P, Panda P, Kasturi P. A comparative meta-analysis of membraneless organelle-associated proteins with age related proteome of C. elegans. Cell Stress Chaperones 2022; 27:619-631. [PMID: 36169889 PMCID: PMC9672229 DOI: 10.1007/s12192-022-01299-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 01/25/2023] Open
Abstract
Proteome imbalance can lead to protein misfolding and aggregation which is associated with pathologies. Protein aggregation can also be an active, organized process and can be exploited by cells as a survival strategy. In adverse conditions, it is beneficial to deposit the proteins in a condensate rather degrading and resynthesizing. Membraneless organelles (MLOs) are biological condensates formed through liquid-liquid phase separation (LLPS), involving cellular components such as nucleic acids and proteins. LLPS is a regulated process, which when perturbed, can undergo a transition from a physiological liquid condensate to pathological solid-like protein aggregates. To understand how the MLO-associated proteins (MLO-APs) behave during aging, we performed a comparative meta-analysis with age-related proteome of C. elegans. We found that the MLO-APs are highly abundant throughout the lifespan in wild-type and long-lived daf-2 mutant animals. Interestingly, they are aggregating more in long-lived mutant animals compared to the age matched wild-type and short-lived daf-16 and hsf-1 mutant animals. GO term analysis revealed that the cell cycle and embryonic development are among the top enriched processes in addition to RNP components in aggregated proteome. Considering antagonistic pleotropic nature of these developmental genes and post mitotic status of C. elegans, we assume that these proteins phase transit during post development. As the organism ages, these MLO-APs either mature to become more insoluble or dissolve in uncontrolled manner. However, in the long-lived daf-2 mutant animals, the MLOs may attain protective states due to extended availability and association of molecular chaperones.
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Affiliation(s)
- Pritam Mukherjee
- BioX Centre, School of Biosciences and Bioengineering, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, 175005, India
| | - Prajnadipta Panda
- BioX Centre, School of Biosciences and Bioengineering, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, 175005, India
| | - Prasad Kasturi
- BioX Centre, School of Biosciences and Bioengineering, Indian Institute of Technology Mandi, Kamand, Himachal Pradesh, 175005, India.
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27
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Quinlan RA, Clark JI. Insights into the biochemical and biophysical mechanisms mediating the longevity of the transparent optics of the eye lens. J Biol Chem 2022; 298:102537. [PMID: 36174677 PMCID: PMC9638808 DOI: 10.1016/j.jbc.2022.102537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/20/2022] [Accepted: 09/22/2022] [Indexed: 11/18/2022] Open
Abstract
In the human eye, a transparent cornea and lens combine to form the "refracton" to focus images on the retina. This requires the refracton to have a high refractive index "n," mediated largely by extracellular collagen fibrils in the corneal stroma and the highly concentrated crystallin proteins in the cytoplasm of the lens fiber cells. Transparency is a result of short-range order in the spatial arrangement of corneal collagen fibrils and lens crystallins, generated in part by post-translational modifications (PTMs). However, while corneal collagen is remodeled continuously and replaced, lens crystallins are very long-lived and are not replaced and so accumulate PTMs over a lifetime. Eventually, a tipping point is reached when protein aggregation results in increased light scatter, inevitably leading to the iconic protein condensation-based disease, age-related cataract (ARC). Cataracts account for 50% of vision impairment worldwide, affecting far more people than other well-known protein aggregation-based diseases. However, because accumulation of crystallin PTMs begins before birth and long before ARC presents, we postulate that the lens protein PTMs contribute to a "cataractogenic load" that not only increases with age but also has protective effects on optical function by stabilizing lens crystallins until a tipping point is reached. In this review, we highlight decades of experimental findings that support the potential for PTMs to be protective during normal development. We hypothesize that ARC is preventable by protecting the biochemical and biophysical properties of lens proteins needed to maintain transparency, refraction, and optical function.
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Affiliation(s)
- Roy A Quinlan
- Department of Biosciences, Durham University, South Road Science Site, Durham, United Kingdom; Department of Biological Structure, University of Washington, Seattle, Washington, USA.
| | - John I Clark
- Department of Biological Structure, University of Washington, Seattle, Washington, USA.
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28
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Gouveia B, Kim Y, Shaevitz JW, Petry S, Stone HA, Brangwynne CP. Capillary forces generated by biomolecular condensates. Nature 2022; 609:255-264. [PMID: 36071192 DOI: 10.1038/s41586-022-05138-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 07/25/2022] [Indexed: 12/21/2022]
Abstract
Liquid-liquid phase separation and related phase transitions have emerged as generic mechanisms in living cells for the formation of membraneless compartments or biomolecular condensates. The surface between two immiscible phases has an interfacial tension, generating capillary forces that can perform work on the surrounding environment. Here we present the physical principles of capillarity, including examples of how capillary forces structure multiphase condensates and remodel biological substrates. As with other mechanisms of intracellular force generation, for example, molecular motors, capillary forces can influence biological processes. Identifying the biomolecular determinants of condensate capillarity represents an exciting frontier, bridging soft matter physics and cell biology.
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Affiliation(s)
- Bernardo Gouveia
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Yoonji Kim
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | | | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA.
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA. .,The Howard Hughes Medical Institute, Princeton, NJ, USA.
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29
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Myosin 1D and the branched actin network control the condensation of p62 bodies. Cell Res 2022; 32:659-669. [PMID: 35477997 DOI: 10.1038/s41422-022-00662-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/01/2022] [Indexed: 11/08/2022] Open
Abstract
Biomolecular condensation driven by liquid-liquid phase separation (LLPS) is key to assembly of membraneless organelles in numerous crucial pathways. It is largely unknown how cellular structures or components spatiotemporally regulate LLPS and condensate formation. Here we reveal that cytoskeletal dynamics can control the condensation of p62 bodies comprising the autophagic adaptor p62/SQSTM1 and poly-ubiquitinated cargos. Branched actin networks are associated with p62 bodies and are required for their condensation. Myosin 1D, a branched actin-associated motor protein, drives coalescence of small nanoscale p62 bodies into large micron-scale condensates along the branched actin network. Impairment of actin cytoskeletal networks compromises the condensation of p62 bodies and retards substrate degradation by autophagy in both cellular models and Myosin 1D knockout mice. Coupling of LLPS scaffold to cytoskeleton systems may represent a general mechanism by which cells exert spatiotemporal control over phase condensation processes.
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30
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Bose M, Lampe M, Mahamid J, Ephrussi A. Liquid-to-solid phase transition of oskar ribonucleoprotein granules is essential for their function in Drosophila embryonic development. Cell 2022; 185:1308-1324.e23. [PMID: 35325593 PMCID: PMC9042795 DOI: 10.1016/j.cell.2022.02.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 11/24/2021] [Accepted: 02/18/2022] [Indexed: 01/05/2023]
Abstract
Asymmetric localization of oskar ribonucleoprotein (RNP) granules to the oocyte posterior is crucial for abdominal patterning and germline formation in the Drosophila embryo. We show that oskar RNP granules in the oocyte are condensates with solid-like physical properties. Using purified oskar RNA and scaffold proteins Bruno and Hrp48, we confirm in vitro that oskar granules undergo a liquid-to-solid phase transition. Whereas the liquid phase allows RNA incorporation, the solid phase precludes incorporation of additional RNA while allowing RNA-dependent partitioning of client proteins. Genetic modification of scaffold granule proteins or tethering the intrinsically disordered region of human fused in sarcoma (FUS) to oskar mRNA allowed modulation of granule material properties in vivo. The resulting liquid-like properties impaired oskar localization and translation with severe consequences on embryonic development. Our study reflects how physiological phase transitions shape RNA-protein condensates to regulate the localization and expression of a maternal RNA that instructs germline formation. oskar RNP granules in the developing oocyte are solid-like condensates oskar RNP granules undergo liquid-to-solid phase transition in vitro The liquid phase incorporates mRNA, while the solid phase enriches specific proteins Perturbing the solid state impairs oskar localization, translation, and development
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Affiliation(s)
- Mainak Bose
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Marko Lampe
- Advanced Light Microscopy Facility, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany.
| | - Anne Ephrussi
- Developmental Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany.
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31
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Huiting W, Dekker SL, van der Lienden JCJ, Mergener R, Musskopf MK, Furtado GV, Gerrits E, Coit D, Oghbaie M, Di Stefano LH, Schepers H, van Waarde-Verhagen MAWH, Couzijn S, Barazzuol L, LaCava J, Kampinga HH, Bergink S. Targeting DNA topoisomerases or checkpoint kinases results in an overload of chaperone systems, triggering aggregation of a metastable subproteome. eLife 2022; 11:70726. [PMID: 35200138 PMCID: PMC8871389 DOI: 10.7554/elife.70726] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 01/07/2022] [Indexed: 02/07/2023] Open
Abstract
A loss of the checkpoint kinase ataxia telangiectasia mutated (ATM) leads to impairments in the DNA damage response, and in humans causes cerebellar neurodegeneration, and an increased risk of cancer. A loss of ATM is also associated with increased protein aggregation. The relevance and characteristics of this aggregation are still incompletely understood. Moreover, it is unclear to what extent other genotoxic conditions can trigger protein aggregation as well. Here, we show that targeting ATM, but also ATR or DNA topoisomerases, results in the widespread aggregation of a metastable, disease-associated subfraction of the proteome. Aggregation-prone model substrates, including Huntingtin exon 1 containing an expanded polyglutamine repeat, aggregate faster under these conditions. This increased aggregation results from an overload of chaperone systems, which lowers the cell-intrinsic threshold for proteins to aggregate. In line with this, we find that inhibition of the HSP70 chaperone system further exacerbates the increased protein aggregation. Moreover, we identify the molecular chaperone HSPB5 as a cell-specific suppressor of it. Our findings reveal that various genotoxic conditions trigger widespread protein aggregation in a manner that is highly reminiscent of the aggregation occurring in situations of proteotoxic stress and in proteinopathies. Cells are constantly perceiving and responding to changes in their surroundings, and challenging conditions such as extreme heat or toxic chemicals can put cells under stress. When this happens, protein production can be affected. Proteins are long chains of chemical building blocks called amino acids, and they can only perform their roles if they fold into the right shape. Some proteins fold easily and remain folded, but others can be unstable and often become misfolded. Unfolded proteins can become a problem because they stick to each other, forming large clumps called aggregates that can interfere with the normal activity of cells, causing damage. The causes of stress that have a direct effect on protein folding are called proteotoxic stresses, and include, for example, high temperatures, which make proteins more flexible and unstable, increasing their chances of becoming unfolded. To prevent proteins becoming misfolded, cells can make ‘protein chaperones’, a type of proteins that help other proteins fold correctly and stay folded. The production of protein chaperones often increases in response to proteotoxic stress. However, there are other types of stress too, such as genotoxic stress, which damages DNA. It is unclear what effect genotoxic stress has on protein folding. Huiting et al. studied protein folding during genotoxic stress in human cells grown in the lab. Stress was induced by either blocking the proteins that repair DNA or by ‘trapping’ the proteins that release DNA tension, both of which result in DNA damage. The analysis showed that, similar to the effects of proteotoxic stress, genotoxic stress increased the number of proteins that aggregate, although certain proteins formed aggregates even without stress, particularly if they were common and relatively unstable proteins. Huiting et al.’s results suggest that aggregation increases in cells under genotoxic stress because the cells fail to produce enough chaperones to effectively fold all the proteins that need it. Indeed, Huiting et al. showed that aggregates contain many proteins that rely on chaperones, and that increasing the number of chaperones in stressed cells reduced protein aggregation. This work shows that genotoxic stress can affect protein folding by limiting the availability of chaperones, which increases protein aggregation. Remarkably, there is a substantial overlap between proteins that aggregate in diseases that affect the brain – such as Alzheimer’s disease – and proteins that aggregate after genotoxic stress. Therefore, further research could focus on determining whether genotoxic stress is involved in the progression of these neurological diseases.
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Affiliation(s)
- Wouter Huiting
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Suzanne L Dekker
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Joris C J van der Lienden
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Rafaella Mergener
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Maiara K Musskopf
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Gabriel V Furtado
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Emma Gerrits
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - David Coit
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, United States
| | - Mehrnoosh Oghbaie
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, United States.,European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Luciano H Di Stefano
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Hein Schepers
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Maria A W H van Waarde-Verhagen
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Suzanne Couzijn
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Lara Barazzuol
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.,Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - John LaCava
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, United States.,European Research Institute for the Biology of Ageing, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Harm H Kampinga
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Steven Bergink
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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32
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Extensile to contractile transition in active microtubule-actin composites generates layered asters with programmable lifetimes. Proc Natl Acad Sci U S A 2022; 119:2115895119. [PMID: 35086931 PMCID: PMC8812548 DOI: 10.1073/pnas.2115895119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2021] [Indexed: 12/15/2022] Open
Abstract
We study a reconstituted composite system consisting of an active microtubule network interdigitated with a passive network of entangled F-actin filaments. Increasing the concentration of filamentous actin controls the emergent dynamics, inducing a transition from turbulent-like flows to bulk contractions. At intermediate concentrations, where the active stresses change their symmetry from anisotropic extensile to isotropic contracting, the composite separates into layered asters that coexist with the background turbulent fluid. Contracted onion-like asters have a radially extending microtubule-rich cortex that envelops alternating layers of microtubules and F-actin. These self-regulating structures undergo internal reorganization, which appears to minimize the surface area and maintain the ordered layering, even when undergoing aster merging events. Finally, the layered asters are metastable structures. Their lifetime, which ranges from minutes to hours, is encoded in the material properties of the composite. These results challenge the current models of active matter. They demonstrate self-organized dynamical states and patterns evocative of those observed in the cytoskeleton do not require precise biochemical regulation, but can arise from purely mechanical interactions of actively driven filamentous materials.
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33
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Fernández-Rico C, Sai T, Sicher A, Style RW, Dufresne ER. Putting the Squeeze on Phase Separation. JACS AU 2022; 2:66-73. [PMID: 35098222 PMCID: PMC8790737 DOI: 10.1021/jacsau.1c00443] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Indexed: 05/06/2023]
Abstract
Phase separation is a ubiquitous process and finds applications in a variety of biological, organic, and inorganic systems. Nature has evolved the ability to control phase separation to both regulate cellular processes and make composite materials with outstanding mechanical and optical properties. Striking examples of the latter are the vibrant blue and green feathers of many bird species, which are thought to result from an exquisite control of the size and spatial correlations of their phase-separated microstructures. By contrast, it is much harder for material scientists to arrest and control phase separation in synthetic materials with such a high level of precision at these length scales. In this Perspective, we briefly review some established methods to control liquid-liquid phase separation processes and then highlight the emergence of a promising arrest method based on phase separation in an elastic polymer network. Finally, we discuss upcoming challenges and opportunities for fabricating microstructured materials via mechanically controlled phase separation.
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34
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Böddeker TJ, Rosowski KA, Berchtold D, Emmanouilidis L, Han Y, Allain FHT, Style RW, Pelkmans L, Dufresne ER. Non-specific adhesive forces between filaments and membraneless organelles. NATURE PHYSICS 2022; 18:571-578. [PMID: 35582428 PMCID: PMC9106579 DOI: 10.1038/s41567-022-01537-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 02/04/2022] [Indexed: 05/07/2023]
Abstract
Many membraneless organelles are liquid-like domains that form inside the active, viscoelastic environment of living cells through phase separation. To investigate the potential coupling of phase separation with the cytoskeleton, we quantify the structural correlations of membraneless organelles (stress granules) and cytoskeletal filaments (microtubules) in a human-derived epithelial cell line. We find that microtubule networks are substantially denser in the vicinity of stress granules. When microtubules are depolymerized, the sub-units localize near the surface of the stress granules. We interpret these data using a thermodynamic model of partitioning of particles to the surface and bulk of the droplets. In this framework, our data are consistent with a weak (≲k B T) affinity of the microtubule sub-units for stress granule interfaces. As microtubules polymerize, their interfacial affinity increases, providing sufficient adhesion to deform droplets and/or the network. Our work suggests that proteins and other objects in the cell have a non-specific affinity for droplet interfaces that increases with the contact area and becomes most apparent when they have no preference for the interior of a droplet over the rest of the cytoplasm. We validate this basic physical phenomenon in vitro through the interaction of a simple protein-RNA condensate with microtubules.
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Affiliation(s)
| | | | - Doris Berchtold
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | | | - Yaning Han
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | | | | | - Lucas Pelkmans
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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35
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Wu YFO, Bryant AT, Nelson NT, Madey AG, Fernandes GF, Goodson HV. Overexpression of the microtubule-binding protein CLIP-170 induces a +TIP network superstructure consistent with a biomolecular condensate. PLoS One 2021; 16:e0260401. [PMID: 34890409 PMCID: PMC8664194 DOI: 10.1371/journal.pone.0260401] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 11/09/2021] [Indexed: 12/02/2022] Open
Abstract
Proper regulation of microtubule (MT) dynamics is critical for cellular processes including cell division and intracellular transport. Plus-end tracking proteins (+TIPs) dynamically track growing MTs and play a key role in MT regulation. +TIPs participate in a complex web of intra- and inter- molecular interactions known as the +TIP network. Hypotheses addressing the purpose of +TIP:+TIP interactions include relieving +TIP autoinhibition and localizing MT regulators to growing MT ends. In addition, we have proposed that the web of +TIP:+TIP interactions has a physical purpose: creating a dynamic scaffold that constrains the structural fluctuations of the fragile MT tip and thus acts as a polymerization chaperone. Here we examine the possibility that this proposed scaffold is a biomolecular condensate (i.e., liquid droplet). Many animal +TIP network proteins are multivalent and have intrinsically disordered regions, features commonly found in biomolecular condensates. Moreover, previous studies have shown that overexpression of the +TIP CLIP-170 induces large “patch” structures containing CLIP-170 and other +TIPs; we hypothesized that these structures might be biomolecular condensates. To test this hypothesis, we used video microscopy, immunofluorescence staining, and Fluorescence Recovery After Photobleaching (FRAP). Our data show that the CLIP-170-induced patches have hallmarks indicative of a biomolecular condensate, one that contains +TIP proteins and excludes other known condensate markers. Moreover, bioinformatic studies demonstrate that the presence of intrinsically disordered regions is conserved in key +TIPs, implying that these regions are functionally significant. Together, these results indicate that the CLIP-170 induced patches in cells are phase-separated liquid condensates and raise the possibility that the endogenous +TIP network might form a liquid droplet at MT ends or other +TIP locations.
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Affiliation(s)
- Yueh-Fu O. Wu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
- Integrated Biomedical Sciences Graduate Program, University of Notre Dame, Notre Dame, IN, United States of America
| | - Annamarie T. Bryant
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
- Integrated Biomedical Sciences Graduate Program, University of Notre Dame, Notre Dame, IN, United States of America
| | - Nora T. Nelson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
| | - Alexander G. Madey
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
| | - Gail F. Fernandes
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
| | - Holly V. Goodson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States of America
- Integrated Biomedical Sciences Graduate Program, University of Notre Dame, Notre Dame, IN, United States of America
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, United States of America
- * E-mail:
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36
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Cavitation controls droplet sizes in elastic media. Proc Natl Acad Sci U S A 2021; 118:2102014118. [PMID: 34588303 DOI: 10.1073/pnas.2102014118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2021] [Indexed: 12/19/2022] Open
Abstract
Biological cells use droplets to separate components and spatially control their interior. Experiments demonstrate that the complex, crowded cellular environment affects the droplet arrangement and their sizes. To understand this behavior, we here construct a theoretical description of droplets growing in an elastic matrix, which is motivated by experiments in synthetic systems where monodisperse emulsions form during a temperature decrease. We show that large droplets only form when they break the surrounding matrix in a cavitation event. The energy barrier associated with cavitation stabilizes small droplets on the order of the mesh size and diminishes the stochastic effects of nucleation. Consequently, the cavitated droplets have similar sizes and highly correlated positions. In particular, we predict the density of cavitated droplets, which increases with faster cooling, as in the experiments. Our model also suggests how adjusting the cooling protocol and the density of nucleation sites affects the droplet size distribution. In summary, our theory explains how elastic matrices affect droplets in the synthetic system, and it provides a framework for understanding the biological case.
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37
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Pareek V, Sha Z, He J, Wingreen NS, Benkovic SJ. Metabolic channeling: predictions, deductions, and evidence. Mol Cell 2021; 81:3775-3785. [PMID: 34547238 PMCID: PMC8485759 DOI: 10.1016/j.molcel.2021.08.030] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 12/19/2022]
Abstract
With the elucidation of myriad anabolic and catabolic enzyme-catalyzed cellular pathways crisscrossing each other, an obvious question arose: how could these networks operate with maximal catalytic efficiency and minimal interference? A logical answer was the postulate of metabolic channeling, which in its simplest embodiment assumes that the product generated by one enzyme passes directly to a second without diffusion into the surrounding medium. This tight coupling of activities might increase a pathway's metabolic flux and/or serve to sequester unstable/toxic/reactive intermediates as well as prevent their access to other networks. Here, we present evidence for this concept, commencing with enzymes that feature a physical molecular tunnel, to multi-enzyme complexes that retain pathway substrates through electrostatics or enclosures, and finally to metabolons that feature collections of enzymes assembled into clusters with variable stoichiometric composition. Lastly, we discuss the advantages of reversibly assembled metabolons in the context of the purinosome, the purine biosynthesis metabolon.
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Affiliation(s)
- Vidhi Pareek
- Huck Institutes of Life Sciences, Pennsylvania State University, University Park, PA 16802, USA
| | - Zhou Sha
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Jingxuan He
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA
| | - Ned S Wingreen
- Department of Molecular Biology and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Stephen J Benkovic
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.
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38
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Ganar KA, Honaker LW, Deshpande S. Shaping synthetic cells through cytoskeleton-condensate-membrane interactions. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101459] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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39
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Cipriani PG, Bay O, Zinno J, Gutwein M, Gan HH, Mayya VK, Chung G, Chen JX, Fahs H, Guan Y, Duchaine TF, Selbach M, Piano F, Gunsalus KC. Novel LOTUS-domain proteins are organizational hubs that recruit C. elegans Vasa to germ granules. eLife 2021; 10:60833. [PMID: 34223818 PMCID: PMC8331183 DOI: 10.7554/elife.60833] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 06/27/2021] [Indexed: 12/16/2022] Open
Abstract
We describe MIP-1 and MIP-2, novel paralogous C. elegans germ granule components that interact with the intrinsically disordered MEG-3 protein. These proteins promote P granule condensation, form granules independently of MEG-3 in the postembryonic germ line, and balance each other in regulating P granule growth and localization. MIP-1 and MIP-2 each contain two LOTUS domains and intrinsically disordered regions and form homo- and heterodimers. They bind and anchor the Vasa homolog GLH-1 within P granules and are jointly required for coalescence of MEG-3, GLH-1, and PGL proteins. Animals lacking MIP-1 and MIP-2 show temperature-sensitive embryonic lethality, sterility, and mortal germ lines. Germline phenotypes include defects in stem cell self-renewal, meiotic progression, and gamete differentiation. We propose that these proteins serve as scaffolds and organizing centers for ribonucleoprotein networks within P granules that help recruit and balance essential RNA processing machinery to regulate key developmental transitions in the germ line.
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Affiliation(s)
- Patricia Giselle Cipriani
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States.,NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Olivia Bay
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - John Zinno
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Michelle Gutwein
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Hin Hark Gan
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Vinay K Mayya
- Goodman Cancer Research Centre and Department of Biochemistry, McGill University, Montreal, Canada
| | - George Chung
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Jia-Xuan Chen
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Hala Fahs
- NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Yu Guan
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Thomas F Duchaine
- Goodman Cancer Research Centre and Department of Biochemistry, McGill University, Montreal, Canada
| | | | - Fabio Piano
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States.,NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Kristin C Gunsalus
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States.,NYU Abu Dhabi Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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40
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Kirschbaum J, Zwicker D. Controlling biomolecular condensates via chemical reactions. J R Soc Interface 2021; 18:20210255. [PMID: 34186016 PMCID: PMC8241490 DOI: 10.1098/rsif.2021.0255] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 06/07/2021] [Indexed: 12/17/2022] Open
Abstract
Biomolecular condensates are small droplets forming spontaneously in biological cells through phase separation. They play a role in many cellular processes, but it is unclear how cells control them. Cellular regulation often relies on post-translational modifications of proteins. For biomolecular condensates, such chemical modifications could alter the molecular interaction of key condensate components. Here, we test this idea using a theoretical model based on non-equilibrium thermodynamics. In particular, we describe the chemical reactions using transition-state theory, which accounts for the non-ideality of phase separation. We identify that fast control, as in cell signalling, is only possible when external energy input drives the reaction out of equilibrium. If this reaction differs inside and outside the droplet, it is even possible to control droplet sizes. Such an imbalance in the reaction could be created by enzymes localizing to the droplet. Since this situation is typical inside cells, we speculate that our proposed mechanism is used to stabilize multiple droplets with independently controlled size and count. Our model provides a novel and thermodynamically consistent framework for describing droplets subject to non-equilibrium chemical reactions.
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Affiliation(s)
- Jan Kirschbaum
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
| | - David Zwicker
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
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41
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Robles-Ramos MÁ, Zorrilla S, Alfonso C, Margolin W, Rivas G, Monterroso B. Assembly of bacterial cell division protein FtsZ into dynamic biomolecular condensates. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118986. [PMID: 33581219 PMCID: PMC8529516 DOI: 10.1016/j.bbamcr.2021.118986] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 11/30/2022]
Abstract
Biomolecular condensation through phase separation may be a novel mechanism to regulate bacterial processes, including cell division. Previous work revealed that FtsZ, a protein essential for cytokinesis in most bacteria, forms biomolecular condensates with SlmA, a protein that protects the chromosome from damage inflicted by the division machinery in Escherichia coli. The absence of condensates composed solely of FtsZ under the conditions used in that study suggested this mechanism was restricted to nucleoid occlusion by SlmA or to bacteria containing this protein. Here we report that FtsZ alone, under physiologically relevant conditions, can demix into condensates in bulk and when encapsulated in synthetic cell-like systems generated by microfluidics. Condensate assembly depends on FtsZ being in the GDP-bound state and on conditions mimicking the crowded environment of the cytoplasm that promote its oligomerization. Condensates are dynamic and reversibly convert into filaments upon GTP addition. Notably, FtsZ lacking its C-terminal disordered region, a structural element likely to favor biomolecular condensation, also forms condensates, albeit less efficiently. The inherent tendency of FtsZ to form condensates susceptible to modulation by physiological factors, including binding partners, suggests that such mechanisms may play a more general role in bacterial division than initially envisioned.
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Affiliation(s)
- Miguel Ángel Robles-Ramos
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - Silvia Zorrilla
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
| | - Carlos Alfonso
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - William Margolin
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas, Houston, TX 77030, USA
| | - Germán Rivas
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
| | - Begoña Monterroso
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
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