1
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Mondal M, Jankoski PE, Lee LD, Dinakarapandian DM, Chiu TY, Swetman WS, Wu H, Paravastu AK, Clemons TD, Rangachari V. Reversible disulfide bond crosslinks as tunable levers of phase separation in designer biomolecular condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.13.603402. [PMID: 39071339 PMCID: PMC11275914 DOI: 10.1101/2024.07.13.603402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Biomolecular condensates (BCs) are membraneless hubs enriched in proteins and nucleic acids that have become important players in many cellular functions. Uncovering the sequence determinants of proteins for phase separation is important in understanding the biophysical and biochemical properties of BCs. Despite significant discoveries in the last decade, the role of cysteine residues in BC formation and dissolution has remained unknown. Here, to determine the involvement of disulfide crosslinks and their redox sensitivity in BCs, we designed a 'stickers and spacers' model of phase-separating peptides interspersed with cysteines. Through biophysical investigations, we learned that cysteines promote liquid-liquid phase separation in oxidizing conditions and perpetuate liquid condensates through disulfide crosslinks, which can be reversibly tuned with redox chemistry. By varying the composition of cysteines, subtle but distinct changes in the viscoelastic behavior of the condensates were observed. Empirically, we conclude that cysteines are neither stickers nor spacers but function as covalent nodes to lower the effective concentrations for sticker interactions and inhibit system-spanning percolation networks. Together, we unmask the role of cysteines in protein phase behavior and the potential to develop tunable, redox-sensitive viscoelastic materials.
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2
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Cairo LV, Hong X, Müller MBD, Yuste-Checa P, Jagadeesan C, Bracher A, Park SH, Hayer-Hartl M, Hartl FU. Stress-dependent condensate formation regulated by the ubiquitin-related modifier Urm1. Cell 2024:S0092-8674(24)00649-4. [PMID: 38942013 DOI: 10.1016/j.cell.2024.06.009] [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: 08/27/2023] [Revised: 04/12/2024] [Accepted: 06/08/2024] [Indexed: 06/30/2024]
Abstract
The ability of proteins and RNA to coalesce into phase-separated assemblies, such as the nucleolus and stress granules, is a basic principle in organizing membraneless cellular compartments. While the constituents of biomolecular condensates are generally well documented, the mechanisms underlying their formation under stress are only partially understood. Here, we show in yeast that covalent modification with the ubiquitin-like modifier Urm1 promotes the phase separation of a wide range of proteins. We find that the drop in cellular pH induced by stress triggers Urm1 self-association and its interaction with both target proteins and the Urm1-conjugating enzyme Uba4. Urmylation of stress-sensitive proteins promotes their deposition into stress granules and nuclear condensates. Yeast cells lacking Urm1 exhibit condensate defects that manifest in reduced stress resilience. We propose that Urm1 acts as a reversible molecular "adhesive" to drive protective phase separation of functionally critical proteins under cellular stress.
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Affiliation(s)
- Lucas V Cairo
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Xiaoyu Hong
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Martin B D Müller
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Patricia Yuste-Checa
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Chandhuru Jagadeesan
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Andreas Bracher
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Sae-Hun Park
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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3
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Weakly HMJ, Keller SL. Coupling liquid phases in 3D condensates and 2D membranes: Successes, challenges, and tools. Biophys J 2024; 123:1329-1341. [PMID: 38160256 PMCID: PMC11163299 DOI: 10.1016/j.bpj.2023.12.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 12/05/2023] [Accepted: 12/26/2023] [Indexed: 01/03/2024] Open
Abstract
This review describes the major experimental challenges researchers meet when attempting to couple phase separation between membranes and condensates. Although it is well known that phase separation in a 2D membrane could affect molecules capable of forming a 3D condensate (and vice versa), few researchers have quantified the effects to date. The scarcity of these measurements is not due to a lack of intense interest or effort in the field. Rather, it reflects significant experimental challenges in manipulating coupled membranes and condensates to yield quantitative values. These challenges transcend many molecular details, which means they impact a wide range of systems. This review highlights recent exciting successes in the field, and it lays out a comprehensive list of tools that address potential pitfalls for researchers who are considering coupling membranes with condensates.
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Affiliation(s)
- Heidi M J Weakly
- Department of Chemistry, University of Washington - Seattle, Seattle, Washington
| | - Sarah L Keller
- Department of Chemistry, University of Washington - Seattle, Seattle, Washington.
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4
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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 PMCID: PMC11238092 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] [Received: 02/05/2024] [Revised: 04/10/2024] [Accepted: 04/19/2024] [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
| | | | - 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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5
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Castelli L, Vasta R, Allen SP, Waller R, Chiò A, Traynor BJ, Kirby J. From use of omics to systems biology: Identifying therapeutic targets for amyotrophic lateral sclerosis. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 176:209-268. [PMID: 38802176 DOI: 10.1016/bs.irn.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Amyotrophic lateral sclerosis (ALS) is a heterogeneous progressive neurodegenerative disorder with available treatments such as riluzole and edaravone extending survival by an average of 3-6 months. The lack of highly effective, widely available therapies reflects the complexity of ALS. Omics technologies, including genomics, transcriptomic and proteomics have contributed to the identification of biological pathways dysregulated and targeted by therapeutic strategies in preclinical and clinical trials. Integrating clinical, environmental and neuroimaging information with omics data and applying a systems biology approach can further improve our understanding of the disease with the potential to stratify patients and provide more personalised medicine. This chapter will review the omics technologies that contribute to a systems biology approach and how these components have assisted in identifying therapeutic targets. Current strategies, including the use of genetic screening and biosampling in clinical trials, as well as the future application of additional technological advances, will also be discussed.
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Affiliation(s)
- Lydia Castelli
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Rosario Vasta
- ALS Expert Center,'Rita Levi Montalcini' Department of Neuroscience, University of Turin, Turin, Italy; Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
| | - Scott P Allen
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Rachel Waller
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Adriano Chiò
- ALS Expert Center,'Rita Levi Montalcini' Department of Neuroscience, University of Turin, Turin, Italy; Neurology 1, Azienda Ospedaliero-Universitaria Città della Salute e della Scienza of Turin, Turin, Italy
| | - Bryan J Traynor
- Neuromuscular Diseases Research Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States; RNA Therapeutics Laboratory, National Center for Advancing Translational Sciences, NIH, Rockville, MD, United States; National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States; Department of Neurology, Johns Hopkins University Medical Center, Baltimore, MD, United States; Reta Lila Weston Institute, UCL Queen Square Institute of Neurology,University College London, London, United Kingdom
| | - Janine Kirby
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom; Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom.
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6
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Park J, Kim JJ, Ryu JK. Mechanism of phase condensation for chromosome architecture and function. Exp Mol Med 2024; 56:809-819. [PMID: 38658703 PMCID: PMC11059216 DOI: 10.1038/s12276-024-01226-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/23/2024] [Accepted: 02/28/2024] [Indexed: 04/26/2024] Open
Abstract
Chromosomal phase separation is involved in a broad spectrum of chromosome organization and functional processes. Nonetheless, the intricacy of this process has left its molecular mechanism unclear. Here, we introduce the principles governing phase separation and its connections to physiological roles in this context. Our primary focus is contrasting two phase separation mechanisms: self-association-induced phase separation (SIPS) and bridging-induced phase separation (BIPS). We provide a comprehensive discussion of the distinct features characterizing these mechanisms and offer illustrative examples that suggest their broad applicability. With a detailed understanding of these mechanisms, we explore their associations with nucleosomes and chromosomal biological functions. This comprehensive review contributes to the exploration of uncharted territory in the intricate interplay between chromosome architecture and function.
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Affiliation(s)
- Jeongveen Park
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Jeong-Jun Kim
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Je-Kyung Ryu
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.
- Institute of Applied Physics of Seoul National University, Seoul, 08826, South Korea.
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, 08826, South Korea.
- Department of Biological Sciences, Seoul National University, Seoul, 08826, South Korea.
- Interdisciplinary Program in Neuroscience, Seoul National University, Seoul, 08826, South Korea.
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7
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Guo D, Xiong Y, Fu B, Sha Z, Li B, Wu H. Liquid-Liquid phase separation in bacteria. Microbiol Res 2024; 281:127627. [PMID: 38262205 DOI: 10.1016/j.micres.2024.127627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/16/2023] [Accepted: 01/15/2024] [Indexed: 01/25/2024]
Abstract
Cells are the essential building blocks of living organisms, responsible for carrying out various biochemical reactions and performing specific functions. In eukaryotic cells, numerous membrane organelles have evolved to facilitate these processes by providing specific spatial locations. In recent years, it has also been discovered that membraneless organelles play a crucial role in the subcellular organization of bacteria, which are single-celled prokaryotic microorganisms characterized by their simple structure and small size. These membraneless organelles in bacteria have been found to undergo Liquid-Liquid phase separation (LLPS), a molecular mechanism that allows for their assembly. Through extensive research, the occurrence of LLPS and its role in the spatial organization of bacteria have been better understood. Various biomacromolecules have been identified to exhibit LLPS properties in different bacterial species. LLPS which is introduced into synthetic biology applies to bacteria has important implications, and three recent research reports have shed light on its potential applications in this field. Overall, this review investigates the molecular mechanisms of LLPS occurrence and its significance in bacteria while also considering the future prospects of implementing LLPS in synthetic biology.
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Affiliation(s)
- Dong Guo
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Yan Xiong
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Beibei Fu
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Zhou Sha
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Bohao Li
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Haibo Wu
- School of Life Sciences, Chongqing University, Chongqing 401331, China.
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8
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Tariq D, Maurici N, Bartholomai BM, Chandrasekaran S, Dunlap JC, Bah A, Crane BR. Phosphorylation, disorder, and phase separation govern the behavior of Frequency in the fungal circadian clock. eLife 2024; 12:RP90259. [PMID: 38526948 PMCID: PMC10963029 DOI: 10.7554/elife.90259] [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] [Indexed: 03/27/2024] Open
Abstract
Circadian clocks are composed of transcription-translation negative feedback loops that pace rhythms of gene expression to the diurnal cycle. In the filamentous fungus Neurospora crassa, the proteins Frequency (FRQ), the FRQ-interacting RNA helicase (FRH), and Casein-Kinase I (CK1) form the FFC complex that represses expression of genes activated by the white-collar complex (WCC). FRQ orchestrates key molecular interactions of the clock despite containing little predicted tertiary structure. Spin labeling and pulse-dipolar electron spin resonance spectroscopy provide domain-specific structural insights into the 989-residue intrinsically disordered FRQ and the FFC. FRQ contains a compact core that associates and organizes FRH and CK1 to coordinate their roles in WCC repression. FRQ phosphorylation increases conformational flexibility and alters oligomeric state, but the changes in structure and dynamics are non-uniform. Full-length FRQ undergoes liquid-liquid phase separation (LLPS) to sequester FRH and CK1 and influence CK1 enzymatic activity. Although FRQ phosphorylation favors LLPS, LLPS feeds back to reduce FRQ phosphorylation by CK1 at higher temperatures. Live imaging of Neurospora hyphae reveals FRQ foci characteristic of condensates near the nuclear periphery. Analogous clock repressor proteins in higher organisms share little position-specific sequence identity with FRQ; yet, they contain amino acid compositions that promote LLPS. Hence, condensate formation may be a conserved feature of eukaryotic clocks.
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Affiliation(s)
- Daniyal Tariq
- Department of Chemistry & Chemical Biology, Cornell UniversityIthacaUnited States
| | - Nicole Maurici
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Bradley M Bartholomai
- Department of Molecular and Systems Biology, Geisel School of Medicine at DartmouthHanoverUnited States
| | | | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at DartmouthHanoverUnited States
| | - Alaji Bah
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical UniversitySyracuseUnited States
| | - Brian R Crane
- Department of Chemistry & Chemical Biology, Cornell UniversityIthacaUnited States
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9
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Rai S, Pramanik S, Mukherjee S. Deciphering the liquid-liquid phase separation induced modulation in the structure, dynamics, and enzymatic activity of an ordered protein β-lactoglobulin. Chem Sci 2024; 15:3936-3948. [PMID: 38487243 PMCID: PMC10935713 DOI: 10.1039/d3sc06802a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 01/23/2024] [Indexed: 03/17/2024] Open
Abstract
Owing to the significant role in the subcellular organization of biomolecules, physiology, and the realm of biomimetic materials, studies related to biomolecular condensates formed through liquid-liquid phase separation (LLPS) have emerged as a growing area of research. Despite valuable contributions of prior research, there is untapped potential in exploring the influence of phase separation on the conformational dynamics and enzymatic activities of native proteins. Herein, we investigate the LLPS of β-lactoglobulin (β-LG), a non-intrinsically disordered protein, under crowded conditions. In-depth characterization through spectroscopic and microscopic techniques revealed the formation of dynamic liquid-like droplets, distinct from protein aggregates, driven by hydrophobic interactions. Our analyses revealed that phase separation can alter structural flexibility and photophysical properties. Importantly, the phase-separated β-LG exhibited efficient enzymatic activity as an esterase; a characteristic seemingly exclusive to β-LG droplets. The droplets acted as robust catalytic crucibles, providing an ideal environment for efficient ester hydrolysis. Further investigation into the catalytic mechanism suggested the involvement of specific amino acid residues, rather than general acid or base catalysis. Also, the alteration in conformational distribution caused by phase separation unveils the latent functionality. Our study delineates the understanding of protein phase separation and insights into the diverse catalytic strategies employed by proteins. It opens exciting possibilities for designing functional artificial compartments based on phase-separated biomolecules.
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Affiliation(s)
- Saurabh Rai
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal Bypass Road Bhopal 462066 Madhya Pradesh India
| | - Srikrishna Pramanik
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal Bypass Road Bhopal 462066 Madhya Pradesh India
| | - Saptarshi Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal Bypass Road Bhopal 462066 Madhya Pradesh India
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10
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Mondal S, Cui Q. Sequence Sensitivity in Membrane Remodeling by Polyampholyte Condensates. J Phys Chem B 2024; 128:2087-2099. [PMID: 38407041 DOI: 10.1021/acs.jpcb.3c08149] [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: 02/27/2024]
Abstract
Intrinsically disordered peptides (IDPs) have been found to undergo liquid-liquid phase separation (LLPS) and produce complex coacervates that play numerous regulatory roles in the cell. Recent experimental studies have discovered that LLPS at or near the membrane surface helps in the biomolecular organization during signaling events and can significantly alter the membrane morphology. However, the molecular mechanism and microscopic details of such processes still remain unclear. Here we study the effect of polyampholyte and polyelectrolyte condensation on two different anionic membranes, as they represent a majority of naturally occurring IDPs. The polyampholytes are fifty-residue polymers, made of glutamate(E) and lysine(K) with different charge patterns. The polyelectrolytes are separate chains of E25 and K25. We first calibrate the MARTINI v3.0 force field and then perform long-time-scale coarse-grained molecular dynamics simulations. We find that condensates formed by all the polyampholytes get adsorbed on the membrane. However, the strong polyampholytes (i.e., blocky sequences) can remodel the membranes more prominently than the weaker ones (i.e., scrambled sequences). Condensates formed by the blocky sequences induce a significant negative curvature (∼0.1 nm-1) and local demixing of lipids, whereas those by the scrambled sequences tend to wet the membrane to a greater extent without generating significant curvature or demixing. We perform several microscopic analyses to characterize the nature of the interaction between membranes and these condensates. Our analyses of interaction energetics reveal that membrane remodeling and/or wetting are favored by enhanced interactions between polyampholytes with lipids and the counterions.
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Affiliation(s)
- Sayantan Mondal
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, Massachusetts 02215, United States
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11
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Holehouse AS, Kragelund BB. The molecular basis for cellular function of intrinsically disordered protein regions. Nat Rev Mol Cell Biol 2024; 25:187-211. [PMID: 37957331 DOI: 10.1038/s41580-023-00673-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2023] [Indexed: 11/15/2023]
Abstract
Intrinsically disordered protein regions exist in a collection of dynamic interconverting conformations that lack a stable 3D structure. These regions are structurally heterogeneous, ubiquitous and found across all kingdoms of life. Despite the absence of a defined 3D structure, disordered regions are essential for cellular processes ranging from transcriptional control and cell signalling to subcellular organization. Through their conformational malleability and adaptability, disordered regions extend the repertoire of macromolecular interactions and are readily tunable by their structural and chemical context, making them ideal responders to regulatory cues. Recent work has led to major advances in understanding the link between protein sequence and conformational behaviour in disordered regions, yet the link between sequence and molecular function is less well defined. Here we consider the biochemical and biophysical foundations that underlie how and why disordered regions can engage in productive cellular functions, provide examples of emerging concepts and discuss how protein disorder contributes to intracellular information processing and regulation of cellular function.
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Affiliation(s)
- Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St Louis, MO, USA.
- Center for Biomolecular Condensates, Washington University in St Louis, St Louis, MO, USA.
| | - Birthe B Kragelund
- REPIN, Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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12
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Zaffagnini G, Cheng S, Salzer MC, Pernaute B, Duran JM, Irimia M, Schuh M, Böke E. Mouse oocytes sequester aggregated proteins in degradative super-organelles. Cell 2024; 187:1109-1126.e21. [PMID: 38382525 DOI: 10.1016/j.cell.2024.01.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 12/04/2023] [Accepted: 01/19/2024] [Indexed: 02/23/2024]
Abstract
Oocytes are among the longest-lived cells in the body and need to preserve their cytoplasm to support proper embryonic development. Protein aggregation is a major threat for intracellular homeostasis in long-lived cells. How oocytes cope with protein aggregation during their extended life is unknown. Here, we find that mouse oocytes accumulate protein aggregates in specialized compartments that we named endolysosomal vesicular assemblies (ELVAs). Combining live-cell imaging, electron microscopy, and proteomics, we found that ELVAs are non-membrane-bound compartments composed of endolysosomes, autophagosomes, and proteasomes held together by a protein matrix formed by RUFY1. Functional assays revealed that in immature oocytes, ELVAs sequester aggregated proteins, including TDP-43, and degrade them upon oocyte maturation. Inhibiting degradative activity in ELVAs leads to the accumulation of protein aggregates in the embryo and is detrimental for embryo survival. Thus, ELVAs represent a strategy to safeguard protein homeostasis in long-lived cells.
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Affiliation(s)
- Gabriele Zaffagnini
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Shiya Cheng
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Marion C Salzer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Barbara Pernaute
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Juan Manuel Duran
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Manuel Irimia
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Melina Schuh
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, 37077 Göttingen, Germany
| | - Elvan Böke
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain.
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13
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Duan C, Wang R. A Unified Description of Salt Effects on the Liquid-Liquid Phase Separation of Proteins. ACS CENTRAL SCIENCE 2024; 10:460-468. [PMID: 38435530 PMCID: PMC10906038 DOI: 10.1021/acscentsci.3c01372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/18/2024] [Accepted: 01/18/2024] [Indexed: 03/05/2024]
Abstract
Protein aggregation via liquid-liquid phase separation (LLPS) is ubiquitous in nature and is intimately connected to many human diseases. Although it is widely known that the addition of salt has crucial impacts on the LLPS of proteins, full understanding of the salt effects remains an outstanding challenge. Here, we develop a molecular theory that systematically incorporates the self-consistent field theory for charged macromolecules into the solution thermodynamics. The electrostatic interaction, hydrophobicity, ion solvation, and translational entropy are included in a unified framework. Our theory fully captures the long-standing puzzles of the nonmonotonic salt concentration dependence and the specific ion effect. We find that proteins show salting-out at low salt concentrations due to ionic screening. The solubility follows the inverse Hofmeister series. In the high salt concentration regime, protein continues salting-out for small ions but turns to salting-in for larger ions, accompanied by the reversal of the Hofmeister series. We reveal that the solubility at high salt concentrations is determined by the competition between the solvation energy and translational entropy of the ion. Furthermore, we derive an analytical criterion for determining the boundary between the salting-in and salting-out regimes, which is in good agreement with experimental results for various proteins and salt ions.
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Affiliation(s)
- Chao Duan
- Department
of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, California 94720, United States
| | - Rui Wang
- Department
of Chemical and Biomolecular Engineering, University of California Berkeley, Berkeley, California 94720, United States
- Materials
Sciences Division, Lawrence Berkeley National
Lab, Berkeley, California 94720, United States
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14
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Chuang CN, Liu HC, Woo TT, Chao JL, Chen CY, Hu HT, Hsueh YP, Wang TF. Noncanonical usage of stop codons in ciliates expands proteins with structurally flexible Q-rich motifs. eLife 2024; 12:RP91405. [PMID: 38393970 PMCID: PMC10942620 DOI: 10.7554/elife.91405] [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] [Indexed: 02/25/2024] Open
Abstract
Serine(S)/threonine(T)-glutamine(Q) cluster domains (SCDs), polyglutamine (polyQ) tracts and polyglutamine/asparagine (polyQ/N) tracts are Q-rich motifs found in many proteins. SCDs often are intrinsically disordered regions that mediate protein phosphorylation and protein-protein interactions. PolyQ and polyQ/N tracts are structurally flexible sequences that trigger protein aggregation. We report that due to their high percentages of STQ or STQN amino acid content, four SCDs and three prion-causing Q/N-rich motifs of yeast proteins possess autonomous protein expression-enhancing activities. Since these Q-rich motifs can endow proteins with structural and functional plasticity, we suggest that they represent useful toolkits for evolutionary novelty. Comparative Gene Ontology (GO) analyses of the near-complete proteomes of 26 representative model eukaryotes reveal that Q-rich motifs prevail in proteins involved in specialized biological processes, including Saccharomyces cerevisiae RNA-mediated transposition and pseudohyphal growth, Candida albicans filamentous growth, ciliate peptidyl-glutamic acid modification and microtubule-based movement, Tetrahymena thermophila xylan catabolism and meiosis, Dictyostelium discoideum development and sexual cycles, Plasmodium falciparum infection, and the nervous systems of Drosophila melanogaster, Mus musculus and Homo sapiens. We also show that Q-rich-motif proteins are expanded massively in 10 ciliates with reassigned TAAQ and TAGQ codons. Notably, the usage frequency of CAGQ is much lower in ciliates with reassigned TAAQ and TAGQ codons than in organisms with expanded and unstable Q runs (e.g. D. melanogaster and H. sapiens), indicating that the use of noncanonical stop codons in ciliates may have coevolved with codon usage biases to avoid triplet repeat disorders mediated by CAG/GTC replication slippage.
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Affiliation(s)
| | - Hou-Cheng Liu
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Tai-Ting Woo
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Ju-Lan Chao
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Chiung-Ya Chen
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Hisao-Tang Hu
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
- Department of Biochemical Science and Technology, National Chiayi UniversityChiayiTaiwan
| | - Ting-Fang Wang
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
- Department of Biochemical Science and Technology, National Chiayi UniversityChiayiTaiwan
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15
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Lin Z, Li D, Zheng J, Yao C, Liu D, Zhang H, Feng H, Chen C, Li P, Zhang Y, Jiang B, Hu Z, Zhao Y, Shi F, Cao D, Rodriguez-Wallberg KA, Li Z, Yeung WSB, Chow LT, Wang H, Liu K. The male pachynema-specific protein MAPS drives phase separation in vitro and regulates sex body formation and chromatin behaviors in vivo. Cell Rep 2024; 43:113651. [PMID: 38175751 DOI: 10.1016/j.celrep.2023.113651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/12/2023] [Accepted: 12/19/2023] [Indexed: 01/06/2024] Open
Abstract
Dynamic chromosome remodeling and nuclear compartmentalization take place during mammalian meiotic prophase I. We report here that the crucial roles of male pachynema-specific protein (MAPS) in pachynema progression might be mediated by its liquid-liquid phase separation in vitro and in cellulo. MAPS forms distinguishable liquid phases, and deletion or mutations of its N-terminal amino acids (aa) 2-9 disrupt its secondary structure and charge properties, impeding phase separation. Maps-/- pachytene spermatocytes exhibit defects in nucleus compartmentalization, including defects in forming sex bodies, altered nucleosome composition, and disordered chromatin accessibility. MapsΔ2-9/Δ2-9 male mice expressing MAPS protein lacking aa 2-9 phenocopy Maps-/- mice. Moreover, a frameshift mutation in C3orf62, the human counterpart of Maps, is correlated with nonobstructive azoospermia in a patient exhibiting pachynema arrest in spermatocyte development. Hence, the phase separation property of MAPS seems essential for pachynema progression in mouse and human spermatocytes.
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Affiliation(s)
- Zexiong Lin
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Dongliang Li
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Jiahuan Zheng
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Chencheng Yao
- Department of Andrology, Center for Men's Health, Department of ART, Institute of Urology, Urologic Medical Center, Shanghai Key Laboratory of Reproductive Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Dongteng Liu
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Hao Zhang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Haiwei Feng
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Chunxu Chen
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Internal Medicine, Division of Hematology, Oncology and Palliative Care, Massey Cancer Institute, Virginia Commonwealth University, Richmond, VA, USA
| | - Peng Li
- Department of Andrology, Center for Men's Health, Department of ART, Institute of Urology, Urologic Medical Center, Shanghai Key Laboratory of Reproductive Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Yuxiang Zhang
- Department of Andrology, Center for Men's Health, Department of ART, Institute of Urology, Urologic Medical Center, Shanghai Key Laboratory of Reproductive Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Binjie Jiang
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Zhe Hu
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Yu Zhao
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Fu Shi
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Dandan Cao
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | | | - Zheng Li
- Department of Andrology, Center for Men's Health, Department of ART, Institute of Urology, Urologic Medical Center, Shanghai Key Laboratory of Reproductive Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - William S B Yeung
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China
| | - Louise T Chow
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Hengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Internal Medicine, Division of Hematology, Oncology and Palliative Care, Massey Cancer Institute, Virginia Commonwealth University, Richmond, VA, USA.
| | - Kui Liu
- Department of Obstetrics and Gynecology, Li Ka Shing Faculty of Medicine; Shenzhen Key Laboratory of Fertility Regulation, Center of Assisted Reproduction and Embryology, The University of Hong Kong-Shenzhen Hospital, The University of Hong Kong, Hong Kong, China.
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16
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Qian H, Ding WX. SQSTM1/p62 and Hepatic Mallory-Denk Body Formation in Alcohol-Associated Liver Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1415-1426. [PMID: 36906265 PMCID: PMC10642158 DOI: 10.1016/j.ajpath.2023.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/14/2023] [Accepted: 02/24/2023] [Indexed: 03/12/2023]
Abstract
Sequestosome 1 (SQSTM1/p62; hereafter p62) is an autophagy receptor protein for selective autophagy primarily due to its direct interaction with the microtubule light chain 3 protein that specifically localizes on autophagosome membranes. As a result, impaired autophagy leads to the accumulation of p62. p62 is also a common component of many human liver disease-related cellular inclusion bodies, such as Mallory-Denk bodies, intracytoplasmic hyaline bodies, α1-antitrypsin aggregates, as well as p62 bodies and condensates. p62 also acts as an intracellular signaling hub, and it involves multiple signaling pathways, including nuclear factor erythroid 2-related factor 2, NF-κB, and the mechanistic target of rapamycin, which are critical for oxidative stress, inflammation, cell survival, metabolism, and liver tumorigenesis. This review discusses the recent insights of p62 in protein quality control, including the role of p62 in the formation and degradation of p62 stress granules and protein aggregates as well as regulation of multiple signaling pathways in the pathogenesis of alcohol-associated liver disease.
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Affiliation(s)
- Hui Qian
- Department of Pharmacology, Toxicology, and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology, and Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas; Department of Internal Medicine, The University of Kansas Medical Center, Kansas City, Kansas.
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17
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Sahoo BR, Bardwell JCA. SERF, a family of tiny highly conserved, highly charged proteins with enigmatic functions. FEBS J 2023; 290:4150-4162. [PMID: 35694898 DOI: 10.1111/febs.16555] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/07/2022] [Accepted: 06/10/2022] [Indexed: 11/27/2022]
Abstract
Amyloid formation is a misfolding process that has been linked to age-related diseases, including Alzheimer's and Huntington's. Understanding how cellular factors affect this process in vivo is vital in realizing the dream of controlling this insidious process that robs so many people of their humanity. SERF (small EDRK-rich factor) was initially isolated as a factor that accelerated polyglutamine amyloid formation in a C. elegans model. SERF knockouts inhibit amyloid formation of a number of proteins that include huntingtin, α-synuclein and β-amyloid which are associated with Huntington's, Parkinson's and Alzheimer's disease, respectively, and purified SERF protein speeds their amyloid formation in vitro. SERF proteins are highly conserved, highly charged and conformationally dynamic proteins that form a fuzzy complex with amyloid precursors. They appear to act by specifically accelerating the primary step of amyloid nucleation. Brain-specific SERF knockout mice, though viable, appear to be more prone to deposition of amyloids, and show modified fibril morphology. Whole-body knockouts are perinatally lethal due to an apparently unrelated developmental issue. Recently, it was found that SERF binds RNA and is localized to nucleic acid-rich membraneless compartments. SERF-related sequences are commonly found fused to zinc finger sequences. These results point towards a nucleic acid-binding function. How this function relates to their ability to accelerate amyloid formation is currently obscure. In this review, we discuss the possible biological functions of SERF family proteins in the context of their structural fuzziness, modulation of amyloid pathway, nucleic acid binding and their fusion to folded proteins.
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Affiliation(s)
- Bikash R Sahoo
- Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
| | - James C A Bardwell
- Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
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18
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Ruiz-Solaní N, Salguero-Linares J, Armengot L, Santos J, Pallarès I, van Midden KP, Phukkan UJ, Koyuncu S, Borràs-Bisa J, Li L, Popa C, Eisele F, Eisele-Bürger AM, Hill SM, Gutiérrez-Beltrán E, Nyström T, Valls M, Llamas E, Vilchez D, Klemenčič M, Ventura S, Coll NS. Arabidopsis metacaspase MC1 localizes in stress granules, clears protein aggregates, and delays senescence. THE PLANT CELL 2023; 35:3325-3344. [PMID: 37401663 PMCID: PMC10473220 DOI: 10.1093/plcell/koad172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 06/07/2023] [Accepted: 06/21/2023] [Indexed: 07/05/2023]
Abstract
Stress granules (SGs) are highly conserved cytoplasmic condensates that assemble in response to stress and contribute to maintaining protein homeostasis. These membraneless organelles are dynamic, disassembling once the stress is no longer present. Persistence of SGs due to mutations or chronic stress has been often related to age-dependent protein-misfolding diseases in animals. Here, we find that the metacaspase MC1 is dynamically recruited into SGs upon proteotoxic stress in Arabidopsis (Arabidopsis thaliana). Two predicted disordered regions, the prodomain and the 360 loop, mediate MC1 recruitment to and release from SGs. Importantly, we show that MC1 has the capacity to clear toxic protein aggregates in vivo and in vitro, acting as a disaggregase. Finally, we demonstrate that overexpressing MC1 delays senescence and this phenotype is dependent on the presence of the 360 loop and an intact catalytic domain. Together, our data indicate that MC1 regulates senescence through its recruitment into SGs and this function could potentially be linked to its remarkable protein aggregate-clearing activity.
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Affiliation(s)
- Nerea Ruiz-Solaní
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona 08028, Spain
| | - Jose Salguero-Linares
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
| | - Laia Armengot
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona 08028, Spain
| | - Jaime Santos
- Institut de Biotecnologia i de Biomedicina, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona 08193, Spain
| | - Irantzu Pallarès
- Institut de Biotecnologia i de Biomedicina, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona 08193, Spain
| | - Katarina P van Midden
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Ujjal J Phukkan
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
| | - Seda Koyuncu
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne 50931, Germany
| | - Júlia Borràs-Bisa
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
| | - Liang Li
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
| | - Crina Popa
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
| | - Frederik Eisele
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Anna Maria Eisele-Bürger
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Sandra Malgrem Hill
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Emilio Gutiérrez-Beltrán
- Instituto de Bioquímica Vegetal y Fotosíntesis (Universidad de Sevilla and Consejo Superior de Investigaciones Científicas), 41092 Seville, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain
| | - Thomas Nyström
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg 41390, Sweden
| | - Marc Valls
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona 08028, Spain
| | - Ernesto Llamas
- Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, University of Cologne, Cologne D-50674, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne 50931, Germany
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne 50931, Germany
- Faculty of Medicine, University Hospital Cologne, Cologne 50931, Germany
| | - Marina Klemenčič
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Salvador Ventura
- Institut de Biotecnologia i de Biomedicina, Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona 08193, Spain
| | - Nuria S Coll
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Bellaterra 08193, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Barcelona 08001, Spain
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19
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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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20
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Gurley NJ, Szymanski RA, Dowen RH, Butcher TA, Ishiyama N, Peifer M. Exploring the evolution and function of Canoe's intrinsically disordered region in linking cell-cell junctions to the cytoskeleton during embryonic morphogenesis. PLoS One 2023; 18:e0289224. [PMID: 37535684 PMCID: PMC10399776 DOI: 10.1371/journal.pone.0289224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/13/2023] [Indexed: 08/05/2023] Open
Abstract
One central question for cell and developmental biologists is defining how epithelial cells can change shape and move during embryonic development without tearing tissues apart. This requires robust yet dynamic connections of cells to one another, via the cell-cell adherens junction, and of junctions to the actin and myosin cytoskeleton, which generates force. The last decade revealed that these connections involve a multivalent network of proteins, rather than a simple linear pathway. We focus on Drosophila Canoe, homolog of mammalian Afadin, as a model for defining the underlying mechanisms. Canoe and Afadin are complex, multidomain proteins that share multiple domains with defined and undefined binding partners. Both also share a long carboxy-terminal intrinsically disordered region (IDR), whose function is less well defined. IDRs are found in many proteins assembled into large multiprotein complexes. We have combined bioinformatic analysis and the use of a series of canoe mutants with early stop codons to explore the evolution and function of the IDR. Our bioinformatic analysis reveals that the IDRs of Canoe and Afadin differ dramatically in sequence and sequence properties. When we looked over shorter evolutionary time scales, we identified multiple conserved motifs. Some of these are predicted by AlphaFold to be alpha-helical, and two correspond to known protein interaction sites for alpha-catenin and F-actin. We next identified the lesions in a series of eighteen canoe mutants, which have early stop codons across the entire protein coding sequence. Analysis of their phenotypes are consistent with the idea that the IDR, including the conserved motifs in the IDR, are critical for protein function. These data provide the foundation for further analysis of IDR function.
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Affiliation(s)
- Noah J. Gurley
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Rachel A. Szymanski
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Robert H. Dowen
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - T. Amber Butcher
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Noboru Ishiyama
- Launchpad Therapeutics, Inc., Cambridge, MA, United States of America
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
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21
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Rangachari V. Biomolecular condensates - extant relics or evolving microcompartments? Commun Biol 2023; 6:656. [PMID: 37344557 PMCID: PMC10284869 DOI: 10.1038/s42003-023-04963-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 05/22/2023] [Indexed: 06/23/2023] Open
Abstract
Unprecedented discoveries during the past decade have unearthed the ubiquitous presence of biomolecular condensates (BCs) in diverse organisms and their involvement in a plethora of biological functions. A predominant number of BCs involve coacervation of RNA and proteins that demix from homogenous solutions by a process of phase separation well described by liquid-liquid phase separation (LLPS), which results in a phase with higher concentration and density from the bulk solution. BCs provide a simple and effective means to achieve reversible spatiotemporal control of cellular processes and adaptation to environmental stimuli in an energy-independent manner. The journey into the past of this phenomenon provides clues to the evolutionary origins of life itself. Here I assemble some current and historic discoveries on LLPS to contemplate whether BCs are extant biological hubs or evolving microcompartments. I conclude that BCs in biology could be extant as a phenomenon but are co-evolving as functionally and compositionally complex microcompartments in cells alongside the membrane-bound organelles.
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Affiliation(s)
- Vijayaraghavan Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences and Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS, 39402, USA.
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22
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Farag M, Holehouse AS, Zeng X, Pappu RV. FIREBALL: A tool to fit protein phase diagrams based on mean-field theories for polymer solutions. Biophys J 2023; 122:2396-2403. [PMID: 37161095 PMCID: PMC10323018 DOI: 10.1016/j.bpj.2023.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 04/26/2023] [Accepted: 05/05/2023] [Indexed: 05/11/2023] Open
Abstract
Biomolecular condensates form via phase transitions of condensate-specific biomacromolecules. Intrinsically disordered regions featuring the appropriate sequence grammars can contribute via homotypic and heterotypic interactions to the driving forces for phase separation of multivalent proteins. Experiments and computations have matured to the point where the concentrations of coexisting dense and dilute phases can be measured or computed for individual intrinsically disordered regions in complex milieus. For a macromolecule such as a disordered protein in a solvent, the locus of points that connects concentrations of the two coexisting phases defines a phase boundary, or binodal. Often, only a few points along the binodal are accessible via measurements. In such cases, and for quantitative and comparative analysis of parameters that describe the driving forces for phase separation, it is useful to fit measured or computed binodals to mean-field free energies for polymer solutions. The nonlinearity of the underlying free energy functions makes it challenging to put mean-field theories into practice. Here, we present FIREBALL, a suite of computational tools designed to enable efficient construction, analysis, and fitting to experimental or computed data of binodals. We show that depending on the theory being used, one can also extract information regarding coil-to-globule transitions of individual macromolecules.
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Affiliation(s)
- Mina Farag
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri; Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, Missouri
| | - Alex S Holehouse
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, Missouri; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri
| | - Xiangze Zeng
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong; Teaching and Research Division, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Rohit V Pappu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri; Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, Missouri.
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23
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Maltseva D, Chatterjee S, Yu CC, Brzezinski M, Nagata Y, Gonella G, Murthy AC, Stachowiak JC, Fawzi NL, Parekh SH, Bonn M. Fibril formation and ordering of disordered FUS LC driven by hydrophobic interactions. Nat Chem 2023:10.1038/s41557-023-01221-1. [PMID: 37231298 PMCID: PMC10396963 DOI: 10.1038/s41557-023-01221-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 04/25/2023] [Indexed: 05/27/2023]
Abstract
Biomolecular condensates, protein-rich and dynamic membrane-less organelles, play critical roles in a range of subcellular processes, including membrane trafficking and transcriptional regulation. However, aberrant phase transitions of intrinsically disordered proteins in biomolecular condensates can lead to the formation of irreversible fibrils and aggregates that are linked to neurodegenerative diseases. Despite the implications, the interactions underlying such transitions remain obscure. Here we investigate the role of hydrophobic interactions by studying the low-complexity domain of the disordered 'fused in sarcoma' (FUS) protein at the air/water interface. Using surface-specific microscopic and spectroscopic techniques, we find that a hydrophobic interface drives fibril formation and molecular ordering of FUS, resulting in solid-like film formation. This phase transition occurs at 600-fold lower FUS concentration than required for the canonical FUS low-complexity liquid droplet formation in bulk. These observations highlight the importance of hydrophobic effects for protein phase separation and suggest that interfacial properties drive distinct protein phase-separated structures.
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Affiliation(s)
- Daria Maltseva
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Sayantan Chatterjee
- Max Planck Institute for Polymer Research, Mainz, Germany
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Chun-Chieh Yu
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Mateusz Brzezinski
- Max Planck Institute for Polymer Research, Mainz, Germany
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Yuki Nagata
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Grazia Gonella
- Max Planck Institute for Polymer Research, Mainz, Germany
- Institute of Biochemistry and Bringing Materials to Life Initiative, ETH Zurich, Zürich, Switzerland
| | - Anastasia C Murthy
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA
| | - Nicolas L Fawzi
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Sapun H Parekh
- Max Planck Institute for Polymer Research, Mainz, Germany.
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, USA.
| | - Mischa Bonn
- Max Planck Institute for Polymer Research, Mainz, Germany.
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24
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Yang S, Shen W, Hu J, Cai S, Zhang C, Jin S, Guan X, Wu J, Wu Y, Cui J. Molecular mechanisms and cellular functions of liquid-liquid phase separation during antiviral immune responses. Front Immunol 2023; 14:1162211. [PMID: 37251408 PMCID: PMC10210139 DOI: 10.3389/fimmu.2023.1162211] [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: 02/09/2023] [Accepted: 04/25/2023] [Indexed: 05/31/2023] Open
Abstract
Spatiotemporal separation of cellular components is vital to ensure biochemical processes. Membrane-bound organelles such as mitochondria and nuclei play a major role in isolating intracellular components, while membraneless organelles (MLOs) are accumulatively uncovered via liquid-liquid phase separation (LLPS) to mediate cellular spatiotemporal organization. MLOs orchestrate various key cellular processes, including protein localization, supramolecular assembly, gene expression, and signal transduction. During viral infection, LLPS not only participates in viral replication but also contributes to host antiviral immune responses. Therefore, a more comprehensive understanding of the roles of LLPS in virus infection may open up new avenues for treating viral infectious diseases. In this review, we focus on the antiviral defense mechanisms of LLPS in innate immunity and discuss the involvement of LLPS during viral replication and immune evasion escape, as well as the strategy of targeting LLPS to treat viral infectious diseases.
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Affiliation(s)
- Shuai Yang
- The First Affiliated Hospital of Sun Yat-sen University, Ministry of Education MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Weishan Shen
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jiajia Hu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Sihui Cai
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chenqiu Zhang
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Shouheng Jin
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiangdong Guan
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jianfeng Wu
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yaoxing Wu
- The First Affiliated Hospital of Sun Yat-sen University, Ministry of Education MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Department of Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jun Cui
- The First Affiliated Hospital of Sun Yat-sen University, Ministry of Education MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- Ministry of Education Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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25
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Zagrovic B, Adlhart M, Kapral TH. Coding From Binding? Molecular Interactions at the Heart of Translation. Annu Rev Biophys 2023; 52:69-89. [PMID: 36626765 DOI: 10.1146/annurev-biophys-090622-102329] [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] [Indexed: 01/11/2023]
Abstract
The mechanism and the evolution of DNA replication and transcription, the key elements of the central dogma of biology, are fundamentally well explained by the physicochemical complementarity between strands of nucleic acids. However, the determinants that have shaped the third part of the dogma-the process of biological translation and the universal genetic code-remain unclear. We review and seek parallels between different proposals that view the evolution of translation through the prism of weak, noncovalent interactions between biological macromolecules. In particular, we focus on a recent proposal that there exists a hitherto unrecognized complementarity at the heart of biology, that between messenger RNA coding regions and the proteins that they encode, especially if the two are unstructured. Reflecting the idea that the genetic code evolved from intrinsic binding propensities between nucleotides and amino acids, this proposal promises to forge a link between the distant past and the present of biological systems.
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Affiliation(s)
- Bojan Zagrovic
- Department of Structural and Computational Biology, Max Perutz Labs & University of Vienna, Vienna, Austria;
| | - Marlene Adlhart
- Department of Structural and Computational Biology, Max Perutz Labs & University of Vienna, Vienna, Austria;
| | - Thomas H Kapral
- Department of Structural and Computational Biology, Max Perutz Labs & University of Vienna, Vienna, Austria;
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
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26
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Hagan MF, Mohajerani F. Self-assembly coupled to liquid-liquid phase separation. PLoS Comput Biol 2023; 19:e1010652. [PMID: 37186597 PMCID: PMC10212142 DOI: 10.1371/journal.pcbi.1010652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 05/25/2023] [Accepted: 04/26/2023] [Indexed: 05/17/2023] Open
Abstract
Liquid condensate droplets with distinct compositions of proteins and nucleic acids are widespread in biological cells. While it is known that such droplets, or compartments, can regulate irreversible protein aggregation, their effect on reversible self-assembly remains largely unexplored. In this article, we use kinetic theory and solution thermodynamics to investigate the effect of liquid-liquid phase separation on the reversible self-assembly of structures with well-defined sizes and architectures. We find that, when assembling subunits preferentially partition into liquid compartments, robustness against kinetic traps and maximum achievable assembly rates can be significantly increased. In particular, both the range of solution conditions leading to productive assembly and the corresponding assembly rates can increase by orders of magnitude. We analyze the rate equation predictions using simple scaling estimates to identify effects of liquid-liquid phase separation as a function of relevant control parameters. These results may elucidate self-assembly processes that underlie normal cellular functions or pathogenesis, and suggest strategies for designing efficient bottom-up assembly for nanomaterials applications.
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Affiliation(s)
- Michael F. Hagan
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts, United States of America
| | - Farzaneh Mohajerani
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts, United States of America
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27
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Swasthi HM, Basalla JL, Dudley CE, Vecchiarelli AG, Chapman MR. Cell surface-localized CsgF condensate is a gatekeeper in bacterial curli subunit secretion. Nat Commun 2023; 14:2392. [PMID: 37100792 PMCID: PMC10133297 DOI: 10.1038/s41467-023-38089-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 04/14/2023] [Indexed: 04/28/2023] Open
Abstract
Curli are functional amyloids present on the outer membrane of E. coli. CsgF is required for the proper assembly of curli. Here, we found that the CsgF phase separates in vitro and that the ability of CsgF variants to phase-separate is tightly correlated with CsgF function during curli biogenesis. Substitution of phenylalanine residues in the CsgF N-terminus both reduced the propensity of CsgF to phase-separate and impaired curli assembly. Exogenous addition of purified CsgF complemented csgF - cells. This exogenous addition assay was used to assess the ability of CsgF variants to complement csgF ‒ cells. CsgF on the cell surface modulated the secretion of CsgA, the curli major subunit, to the cell surface. We also found that the CsgB nucleator protein can form SDS-insoluble aggregates within the dynamic CsgF condensate. We propose that these multicomponent CsgF-B condensates form a nucleation-competent complex that templates CsgA amyloid formation on the cell surface.
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Affiliation(s)
- Hema M Swasthi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048, USA
| | - Joseph L Basalla
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048, USA
| | - Claire E Dudley
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048, USA
| | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048, USA
| | - Matthew R Chapman
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109-1048, USA.
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28
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Farag M, Holehouse AS, Zeng X, Pappu RV. FIREBALL: A tool to fit protein phase diagrams based on mean-field theories for polymer solutions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.19.533322. [PMID: 36993371 PMCID: PMC10055191 DOI: 10.1101/2023.03.19.533322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Biomolecular condensates form via phase transitions of condensate-specific biomacromolecules. Intrinsically disordered regions (IDRs) featuring the appropriate sequence grammar can contribute homotypic and heterotypic interactions to the driving forces for phase separation of multivalent proteins. At this juncture, experiments and computations have matured to the point where the concentrations of coexisting dense and dilute phases can be quantified for individual IDRs in complex milieus both in vitro and in vivo . For a macromolecule such as a disordered protein in a solvent, the locus of points that connects concentrations of the two coexisting phases defines a phase boundary or binodal. Often, only a few points along the binodal, especially in the dense phase, are accessible for measurement. In such cases and for quantitative and comparative analysis of parameters that describe the driving forces for phase separation, it is useful to fit measured or computed binodals to well-known mean-field free energies for polymer solutions. Unfortunately, the non-linearity of the underlying free energy functions makes it challenging to put mean-field theories into practice. Here, we present FIREBALL, a suite of computational tools designed to enable efficient construction, analysis, and fitting to experimental or computed data of binodals. We show that depending on the theory being used, one can also extract information regarding coil-to-globule transitions of individual macromolecules. Here, we emphasize the ease-of-use and utility of FIREBALL using examples based on data for two different IDRs. Statement of Significance Macromolecular phase separation drives the assembly of membraneless bodies known as biomolecular condensates. Measurements and computer simulations can now be brought to bear to quantify how the concentrations of macromolecules in coexisting dilute and dense phases vary with changes to solution conditions. These mappings can be fit to analytical expressions for free energies of solution to extract information regarding parameters that enable comparative assessments of the balance of macromolecule-solvent interactions across different systems. However, the underlying free energies are non-linear and fitting them to actual data is non-trivial. To enable comparative numerical analyses, we introduce FIREBALL, a user-friendly suite of computational tools that allows one to generate, analyze, and fit phase diagrams and coil-to-globule transitions using well-known theories.
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29
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Light, Water, and Melatonin: The Synergistic Regulation of Phase Separation in Dementia. Int J Mol Sci 2023; 24:ijms24065835. [PMID: 36982909 PMCID: PMC10054283 DOI: 10.3390/ijms24065835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/17/2023] [Indexed: 03/22/2023] Open
Abstract
The swift rise in acceptance of molecular principles defining phase separation by a broad array of scientific disciplines is shadowed by increasing discoveries linking phase separation to pathological aggregations associated with numerous neurodegenerative disorders, including Alzheimer’s disease, that contribute to dementia. Phase separation is powered by multivalent macromolecular interactions. Importantly, the release of water molecules from protein hydration shells into bulk creates entropic gains that promote phase separation and the subsequent generation of insoluble cytotoxic aggregates that drive healthy brain cells into diseased states. Higher viscosity in interfacial waters and limited hydration in interiors of biomolecular condensates facilitate phase separation. Light, water, and melatonin constitute an ancient synergy that ensures adequate protein hydration to prevent aberrant phase separation. The 670 nm visible red wavelength found in sunlight and employed in photobiomodulation reduces interfacial and mitochondrial matrix viscosity to enhance ATP production via increasing ATP synthase motor efficiency. Melatonin is a potent antioxidant that lowers viscosity to increase ATP by scavenging excess reactive oxygen species and free radicals. Reduced viscosity by light and melatonin elevates the availability of free water molecules that allow melatonin to adopt favorable conformations that enhance intrinsic features, including binding interactions with adenosine that reinforces the adenosine moiety effect of ATP responsible for preventing water removal that causes hydrophobic collapse and aggregation in phase separation. Precise recalibration of interspecies melatonin dosages that account for differences in metabolic rates and bioavailability will ensure the efficacious reinstatement of the once-powerful ancient synergy between light, water, and melatonin in a modern world.
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30
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Gurley NJ, Szymanski RA, Dowen RH, Butcher TA, Ishiyama N, Peifer M. Exploring the evolution and function of Canoe’s intrinsically disordered region in linking cell-cell junctions to the cytoskeleton during embryonic morphogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.06.531372. [PMID: 36945496 PMCID: PMC10028902 DOI: 10.1101/2023.03.06.531372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
One central question for cell and developmental biologists is defining how epithelial cells can change shape and move during embryonic development without tearing tissues apart. This requires robust yet dynamic connections of cells to one another, via the cell-cell adherens junction, and of junctions to the actin and myosin cytoskeleton, which generates force. The last decade revealed that these connections involve a multivalent network of proteins, rather than a simple linear pathway. We focus on Drosophila Canoe, homolog of mammalian Afadin, as a model for defining the underlying mechanisms. Canoe and Afadin are complex, multidomain proteins that share multiple domains with defined and undefined binding partners. Both also share a long carboxy-terminal intrinsically disordered region (IDR), whose function is less well defined. IDRs are found in many proteins assembled into large multiprotein complexes. We have combined bioinformatic analysis and the use of a series of canoe mutants with early stop codons to explore the evolution and function of the IDR. Our bioinformatic analysis reveals that the IDRs of Canoe and Afadin differ dramatically in sequence and sequence properties. When we looked over shorter evolutionary time scales, we identified multiple conserved motifs. Some of these are predicted by AlphaFold to be alpha-helical, and two correspond to known protein interaction sites for alpha-catenin and F-actin. We next identified the lesions in a series of eighteen canoe mutants, which have early stop codons across the entire protein coding sequence. Analysis of their phenotypes are consistent with the idea that the IDR, including its C-terminal conserved motifs, are important for protein function. These data provide the foundation for further analysis of IDR function.
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Affiliation(s)
- Noah J. Gurley
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
| | - Rachel A Szymanski
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
| | - Robert H Dowen
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - T. Amber Butcher
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
| | - Noboru Ishiyama
- Launchpad Therapeutics, Inc., One Main Street, Cambridge MA 02142
| | - Mark Peifer
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Chapel Hill, NC 27599-3280, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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31
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Goodsell DS, Lasker K. Integrative visualization of the molecular structure of a cellular microdomain. Protein Sci 2023; 32:e4577. [PMID: 36700303 PMCID: PMC9926476 DOI: 10.1002/pro.4577] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/16/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023]
Abstract
An integrative approach to visualization is used to create a visual snapshot of the structural biology of the polar microdomain of Caulobacter crescentus. The visualization is based on the current state of molecular and cellular knowledge of the microdomain and its cellular context. The collaborative process of researching and executing the visualization has identified aspects that are well determined and areas that require further study. The visualization is useful for dissemination, education, and outreach, and the study lays the groundwork for future 3D modeling and simulation of this well-studied example of a cellular condensate.
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Affiliation(s)
- David S Goodsell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA.,Research Collaboratory for Structural Bioinformatics Protein Data Bank, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.,Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.,Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Keren Lasker
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
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32
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Das D, Deniz AA. Topological Considerations in Biomolecular Condensation. Biomolecules 2023; 13:151. [PMID: 36671536 PMCID: PMC9855981 DOI: 10.3390/biom13010151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/07/2023] [Accepted: 01/09/2023] [Indexed: 01/13/2023] Open
Abstract
Biomolecular condensation and phase separation are increasingly understood to play crucial roles in cellular compartmentalization and spatiotemporal regulation of cell machinery implicated in function and pathology. A key aspect of current research is to gain insight into the underlying physical mechanisms of these processes. Accordingly, concepts of soft matter and polymer physics, the thermodynamics of mixing, and material science have been utilized for understanding condensation mechanisms of multivalent macromolecules resulting in viscoelastic mesoscopic supramolecular assemblies. Here, we focus on two topological concepts that have recently been providing key mechanistic understanding in the field. First, we will discuss how percolation provides a network-topology-related framework that offers an interesting paradigm to understand the complex networking of dense 'connected' condensate structures and, therefore, their phase behavior. Second, we will discuss the idea of entanglement as another topological concept that has deep roots in polymer physics and important implications for biomolecular condensates. We will first review some historical developments and fundamentals of these concepts, then we will discuss current advancements and recent examples. Our discussion ends with a few open questions and the challenges to address them, hinting at unveiling fresh possibilities for the modification of existing knowledge as well as the development of new concepts relevant to condensate science.
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Affiliation(s)
| | - Ashok A. Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA
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33
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Valdes-Garcia G, Heo L, Lapidus LJ, Feig M. Modeling Concentration-dependent Phase Separation Processes Involving Peptides and RNA via Residue-Based Coarse-Graining. J Chem Theory Comput 2023; 19:10.1021/acs.jctc.2c00856. [PMID: 36607820 PMCID: PMC10323037 DOI: 10.1021/acs.jctc.2c00856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Biomolecular condensation, especially liquid-liquid phase separation, is an important physical process with relevance for a number of different aspects of biological functions. Key questions of what drives such condensation, especially in terms of molecular composition, can be addressed via computer simulations, but the development of computationally efficient yet physically realistic models has been challenging. Here, the coarse-grained model COCOMO is introduced that balances the polymer behavior of peptides and RNA chains with their propensity to phase separate as a function of composition and concentration. COCOMO is a residue-based model that combines bonded terms with short- and long-range terms, including a Debye-Hückel solvation term. The model is highly predictive of experimental data on phase-separating model systems. It is also computationally efficient and can reach the spatial and temporal scales on which biomolecular condensation is observed with moderate computational resources.
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Affiliation(s)
- Gilberto Valdes-Garcia
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Lim Heo
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Lisa J. Lapidus
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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34
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Ginell GM, Holehouse AS. An Introduction to the Stickers-and-Spacers Framework as Applied to Biomolecular Condensates. Methods Mol Biol 2023; 2563:95-116. [PMID: 36227469 DOI: 10.1007/978-1-0716-2663-4_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Cellular organization is determined by a combination of membrane-bound and membrane-less biomolecular assemblies that range from clusters of tens of molecules to micrometer-sized cellular bodies. Over the last decade, membrane-less assemblies have come to be referred to as biomolecular condensates, reflecting their ability to condense specific molecules with respect to the remainder of the cell. In many cases, the physics of phase transitions provides a conceptual framework and a mathematical toolkit to describe the assembly, maintenance, and dissolution of biomolecular condensates. Among the various quantitative and qualitative models applied to understand intracellular phase transitions, the stickers-and-spacers framework offers an intuitive yet rigorous means to map biomolecular sequences and structure to the driving forces needed for higher-order assembly. This chapter introduces the fundamental concepts behind the stickers-and-spacers model, considers its application to different biological systems, and discusses limitations and misconceptions around the model.
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Affiliation(s)
- Garrett M Ginell
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO, USA
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA.
- Center for Science & Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO, USA.
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35
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Raymond-Smiedy P, Bucknor B, Yang Y, Zheng T, Castañeda CA. A Spectrophotometric Turbidity Assay to Study Liquid-Liquid Phase Separation of UBQLN2 In Vitro. Methods Mol Biol 2023; 2551:515-541. [PMID: 36310223 DOI: 10.1007/978-1-0716-2597-2_32] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Liquid-liquid phase separation (LLPS) is hypothesized to be the underlying mechanism for how membraneless organelles or biomolecular condensates form inside both prokaryotic and eukaryotic cells. Protein LLPS is a biophysical process during which proteins demix from homogeneous solution to form protein-dense droplets with liquid-like properties. Disruptions to LLPS, such as changes to material properties of condensates or physicochemical parameters for LLPS onset, are implicated in neurodegenerative diseases and cancer. Therefore, it is essential to determine the physicochemical parameters that promote protein LLPS. Here, we present our UV-Vis spectrophotometric turbidity assay to characterize the temperature and concentration dependence of LLPS for UBQLN2, a protein that undergoes LLPS via homotypic interactions in vitro and forms stress-induced condensates in cells. Mutations in UBQLN2 cause amyotrophic lateral sclerosis (ALS) and disrupt UBQLN2 LLPS. We present a detailed expression and purification protocol for a C-terminal construct of UBQLN2 and how we use microscopy to image UBQLN2 LLPS. We use our UV-Vis assay to construct temperature-concentration phase diagrams for wild-type and mutant UBQLN2 constructs to determine the effects of domain deletions and/or mutations on UBQLN2 phase separation.
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Affiliation(s)
| | - Barrington Bucknor
- Department of Biology, Syracuse University, Syracuse, NY, USA
- Department of Chemistry, Syracuse University, Syracuse, NY, USA
- Program in Neuroscience, Syracuse University, Syracuse, NY, USA
| | - Yiran Yang
- Department of Chemistry, Syracuse University, Syracuse, NY, USA
| | - Tongyin Zheng
- Department of Chemistry, Syracuse University, Syracuse, NY, USA
| | - Carlos A Castañeda
- Department of Biology, Syracuse University, Syracuse, NY, USA.
- Department of Chemistry, Syracuse University, Syracuse, NY, USA.
- Program in Neuroscience, Syracuse University, Syracuse, NY, USA.
- BioInspired Institute, Syracuse University, Syracuse, NY, USA.
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Poly(ADP-ribose) in Condensates: The PARtnership of Phase Separation and Site-Specific Interactions. Int J Mol Sci 2022; 23:ijms232214075. [PMID: 36430551 PMCID: PMC9694962 DOI: 10.3390/ijms232214075] [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: 10/14/2022] [Revised: 11/09/2022] [Accepted: 11/11/2022] [Indexed: 11/17/2022] Open
Abstract
Biomolecular condensates are nonmembrane cellular compartments whose formation in many cases involves phase separation (PS). Despite much research interest in this mechanism of macromolecular self-organization, the concept of PS as applied to a live cell faces certain challenges. In this review, we discuss a basic model of PS and the role of site-specific interactions and percolation in cellular PS-related events. Using a multivalent poly(ADP-ribose) molecule as an example, which has high PS-driving potential due to its structural features, we consider how site-specific interactions and network formation are involved in the formation of phase-separated cellular condensates.
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37
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Londoño Vélez V, Alquraish F, Tarbiyyah I, Rafique F, Mao D, Chodasiewicz M. Landscape of biomolecular condensates in heat stress responses. FRONTIERS IN PLANT SCIENCE 2022; 13:1032045. [PMID: 36311142 PMCID: PMC9601738 DOI: 10.3389/fpls.2022.1032045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/21/2022] [Indexed: 06/06/2023]
Abstract
High temperature is one of the abiotic stresses that plants face and acts as a major constraint on crop production and food security. Plants have evolved several mechanisms to overcome challenging environments and respond to internal and external stimuli. One significant mechanism is the formation of biomolecular condensates driven by liquid-liquid phase separation. Biomolecular condensates have received much attention in the past decade, especially with regard to how plants perceive temperature fluctuations and their involvement in stress response and tolerance. In this review, we compile and discuss examples of plant biomolecular condensates regarding their composition, localization, and functions triggered by exposure to heat. Bioinformatic tools can be exploited to predict heat-induced biomolecular condensates. As the field of biomolecular condensates has emerged in the study of plants, many intriguing questions have arisen that have yet to be solved. Increased knowledge of biomolecular condensates will help in securing crop production and overcoming limitations caused by heat stress.
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38
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Tarczewska A, Bielak K, Zoglowek A, Sołtys K, Dobryszycki P, Ożyhar A, Różycka M. The Role of Intrinsically Disordered Proteins in Liquid–Liquid Phase Separation during Calcium Carbonate Biomineralization. Biomolecules 2022; 12:biom12091266. [PMID: 36139105 PMCID: PMC9496343 DOI: 10.3390/biom12091266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Some animal organs contain mineralized tissues. These so-called hard tissues are mostly deposits of calcium salts, usually in the form of calcium phosphate or calcium carbonate. Examples of this include fish otoliths and mammalian otoconia, which are found in the inner ear, and they are an essential part of the sensory system that maintains body balance. The composition of ear stones is quite well known, but the role of individual components in the nucleation and growth of these biominerals is enigmatic. It is sure that intrinsically disordered proteins (IDPs) play an important role in this aspect. They have an impact on the shape and size of otoliths. It seems probable that IDPs, with their inherent ability to phase separate, also play a role in nucleation processes. This review discusses the major theories on the mechanisms of biomineral nucleation with a focus on the importance of protein-driven liquid–liquid phase separation (LLPS). It also presents the current understanding of the role of IDPs in the formation of calcium carbonate biominerals and predicts their potential ability to drive LLPS.
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Ruff KM, Choi YH, Cox D, Ormsby AR, Myung Y, Ascher DB, Radford SE, Pappu RV, Hatters DM. Sequence grammar underlying the unfolding and phase separation of globular proteins. Mol Cell 2022; 82:3193-3208.e8. [PMID: 35853451 PMCID: PMC10846692 DOI: 10.1016/j.molcel.2022.06.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 05/05/2022] [Accepted: 06/15/2022] [Indexed: 12/23/2022]
Abstract
Aberrant phase separation of globular proteins is associated with many diseases. Here, we use a model protein system to understand how the unfolded states of globular proteins drive phase separation and the formation of unfolded protein deposits (UPODs). We find that for UPODs to form, the concentrations of unfolded molecules must be above a threshold value. Additionally, unfolded molecules must possess appropriate sequence grammars to drive phase separation. While UPODs recruit molecular chaperones, their compositional profiles are also influenced by synergistic physicochemical interactions governed by the sequence grammars of unfolded proteins and cellular proteins. Overall, the driving forces for phase separation and the compositional profiles of UPODs are governed by the sequence grammars of unfolded proteins. Our studies highlight the need for uncovering the sequence grammars of unfolded proteins that drive UPOD formation and cause gain-of-function interactions whereby proteins are aberrantly recruited into UPODs.
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Affiliation(s)
- Kiersten M Ruff
- Department of Biomedical Engineering, Center for Science & Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Yoon Hee Choi
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Dezerae Cox
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Angelique R Ormsby
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Yoochan Myung
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia; Structural Biology and Bioinformatics, Department of Biochemistry and Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia; Systems and Computational Biology, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - David B Ascher
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia; Structural Biology and Bioinformatics, Department of Biochemistry and Pharmacology, The University of Melbourne, Melbourne, VIC 3010, Australia; Systems and Computational Biology, Bio21 Institute, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Sheena E Radford
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Rohit V Pappu
- Department of Biomedical Engineering, Center for Science & Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130, USA.
| | - Danny M Hatters
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.
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Wei W, Bai L, Yan B, Meng W, Wang H, Zhai J, Si F, Zheng C. When liquid-liquid phase separation meets viral infections. Front Immunol 2022; 13:985622. [PMID: 36016945 PMCID: PMC9395683 DOI: 10.3389/fimmu.2022.985622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/20/2022] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic cells have both membranous and membraneless organelles. While the formation mechanism of membranous organelles is well understood, the formation mechanism of membraneless organelles remains unknown. Many biomolecules in the cytoplasm transition from the liquid phase to the agglutinated phase are known as liquid-liquid phase separation (LLPS). The biomolecular agglomerates’ physical properties enable them to function as dynamic compartments that respond to external pressures and stimuli. Scientists have gradually recognized the importance of phase separation during viral infections. LLPS provides a powerful new framework for understanding the viral life cycle from viral replication to evasion of host immune surveillance. As a result, this review focuses on the progress of LLPS research in viral infection and immune regulation to provide clues for antiviral therapeutic strategies.
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Affiliation(s)
- Wenqiang Wei
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Lu Bai
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Bing Yan
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Weiquan Meng
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Hongju Wang
- Kaifeng Key Laboratory of Infection and Biological Safety, School of Basic Medical Sciences, Henan University, Kaifeng, China
| | - Jingbo Zhai
- Medical College, Inner Mongolia Minzu University, Tongliao, China
- Key Laboratory of Zoonose Prevention and Control at Universities of Inner Mongolia Autonomous Region, Tongliao, China
| | - Fusheng Si
- Institute of Animal Science and Veterinary Medicine, Shanghai Key Laboratory of Agricultural Genetics and Breeding, Shanghai Engineering Research Center of Breeding Pig, Shanghai Academy of Agricultural Sciences, Shanghai, China
- *Correspondence: Chunfu Zheng, ; Fusheng Si,
| | - Chunfu Zheng
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, AB, Canada
- *Correspondence: Chunfu Zheng, ; Fusheng Si,
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41
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Michieletto D, Marenda M. Rheology and Viscoelasticity of Proteins and Nucleic Acids Condensates. JACS AU 2022; 2:1506-1521. [PMID: 35911447 PMCID: PMC9326828 DOI: 10.1021/jacsau.2c00055] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Phase separation is as familiar as watching vinegar separating from oil in vinaigrette. The observation that phase separation of proteins and nucleic acids is widespread in living cells has opened an entire field of research into the biological significance and the biophysical mechanisms of phase separation and protein condensation in biology. Recent evidence indicates that certain proteins and nucleic acids condensates are not simple liquids and instead display both viscous and elastic behaviors, which in turn may have biological significance. The aim of this Perspective is to review the state-of-the-art of this quickly emerging field focusing on the material and rheological properties of protein condensates. Finally, we discuss the different techniques that can be employed to quantify the viscoelasticity of condensates and highlight potential future directions and opportunities for interdisciplinary cross-talk between chemists, physicists, and biologists.
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Affiliation(s)
- Davide Michieletto
- School
of Physics and Astronomy, University of
Edinburgh, Peter Guthrie
Tait Road, Edinburgh EH9
3FD, U.K.
- MRC
Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, U.K.
| | - Mattia Marenda
- School
of Physics and Astronomy, University of
Edinburgh, Peter Guthrie
Tait Road, Edinburgh EH9
3FD, U.K.
- MRC
Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, U.K.
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42
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Mondal S, Cui Q. Coacervation of poly-electrolytes in the presence of lipid bilayers: mutual alteration of structure and morphology. Chem Sci 2022; 13:7933-7946. [PMID: 35865903 PMCID: PMC9258347 DOI: 10.1039/d2sc02013k] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/13/2022] [Indexed: 11/21/2022] Open
Abstract
Many intrinsically disordered peptides have been shown to undergo liquid-liquid phase separation and form complex coacervates, which play various regulatory roles in the cell. Recent experimental studies found that such phase separation processes may also occur at the lipid membrane surface and help organize biomolecules during signaling events; in some cases, phase separation of proteins at the membrane surface was also observed to lead to significant remodeling of the membrane morphology. The molecular mechanisms that govern the interactions between complex coacervates and lipid membranes and the impacts of such interactions on their structure and morphology, however, remain unclear. Here we study the coacervation of poly-glutamate (E30) and poly-lysine (K30) in the presence of lipid bilayers of different compositions. We carry out explicit-solvent coarse-grained molecular dynamics simulations by using the MARTINI (v3.0) force-field. We find that more than 20% anionic lipids are required for the coacervate to form stable contact with the bilayer. Upon wetting, the coacervate induces negative curvature to the bilayer and facilitates local lipid demixing, without any peptide insertion. The magnitude of negative curvature, extent of lipid demixing, and asphericity of the coacervate increase with the concentration of anionic lipids. Overall, we observe a decrease in the number of contacts among the polyelectrolytes as the droplet spreads over the bilayer. Therefore, unlike previous suggestions, interactions among polyelectrolytes do not constitute a driving force for the membrane bending upon wetting by the coacervate. Rather, analysis of interaction energy components suggests that bending of the membrane is favored by enhanced interactions between polyelectrolytes with lipids as well as with counterions. Kinetic studies reveal that, at the studied polyelectrolyte concentrations, the coacervate formation precedes bilayer wetting.
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Affiliation(s)
- Sayantan Mondal
- Department of Chemistry, Boston University 590 Commonwealth Avenue Boston MA 02215 USA (+1)-617-353-6189
| | - Qiang Cui
- Department of Chemistry, Boston University 590 Commonwealth Avenue Boston MA 02215 USA (+1)-617-353-6189
- Department of Physics, Boston University 590 Commonwealth Avenue Boston MA 02215 USA
- Department of Biomedical Engineering, Boston University 44 Cummington Mall Boston MA 02215 USA
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43
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Fernandez-Gonzalez R, Peifer M. Powering morphogenesis: multiscale challenges at the interface of cell adhesion and the cytoskeleton. Mol Biol Cell 2022; 33. [PMID: 35696393 DOI: 10.1091/mbc.e21-09-0452] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Among the defining features of the animal kingdom is the ability of cells to change shape and move. This underlies embryonic and postembryonic development, tissue homeostasis, regeneration, and wound healing. Cell shape change and motility require linkage of the cell's force-generating machinery to the plasma membrane at cell-cell and cell-extracellular matrix junctions. Connections of the actomyosin cytoskeleton to cell-cell adherens junctions need to be both resilient and dynamic, preventing tissue disruption during the dramatic events of embryonic morphogenesis. In the past decade, new insights radically altered the earlier simple paradigm that suggested simple linear linkage via the cadherin-catenin complex as the molecular mechanism of junction-cytoskeleton interaction. In this Perspective we provide a brief overview of our current state of knowledge and then focus on selected examples highlighting what we view as the major unanswered questions in our field and the approaches that offer exciting new insights at multiple scales from atomic structure to tissue mechanics.
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Affiliation(s)
- Rodrigo Fernandez-Gonzalez
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G5, Canada.,Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5S 3G5, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.,Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Mark Peifer
- Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599-3280.,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
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44
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Tsidilkovski L, Mohajerani F, Hagan MF. Microcompartment assembly around multicomponent fluid cargoes. J Chem Phys 2022; 156:245104. [PMID: 35778087 PMCID: PMC9249432 DOI: 10.1063/5.0089556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This article describes dynamical simulations of the assembly of an icosahedral protein shell around a bicomponent fluid cargo. Our simulations are motivated by bacterial microcompartments, which are protein shells found in bacteria that assemble around a complex of enzymes and other components involved in certain metabolic processes. The simulations demonstrate that the relative interaction strengths among the different cargo species play a key role in determining the amount of each species that is encapsulated, their spatial organization, and the nature of the shell assembly pathways. However, the shell protein–shell protein and shell protein–cargo component interactions that help drive assembly and encapsulation also influence cargo composition within certain parameter regimes. These behaviors are governed by a combination of thermodynamic and kinetic effects. In addition to elucidating how natural microcompartments encapsulate multiple components involved within reaction cascades, these results have implications for efforts in synthetic biology to colocalize alternative sets of molecules within microcompartments to accelerate specific reactions. More broadly, the results suggest that coupling between self-assembly and multicomponent liquid–liquid phase separation may play a role in the organization of the cellular cytoplasm.
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Affiliation(s)
- Lev Tsidilkovski
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Farzaneh Mohajerani
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
| | - Michael F Hagan
- Martin A. Fisher School of Physics, Brandeis University, Waltham, Massachusetts 02453, USA
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45
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Linsenmeier M, Hondele M, Grigolato F, Secchi E, Weis K, Arosio P. Dynamic arrest and aging of biomolecular condensates are modulated by low-complexity domains, RNA and biochemical activity. Nat Commun 2022; 13:3030. [PMID: 35641495 PMCID: PMC9156751 DOI: 10.1038/s41467-022-30521-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 04/27/2022] [Indexed: 11/18/2022] Open
Abstract
Biomolecular condensates require suitable control of material properties for their function. Here we apply Differential Dynamic Microscopy (DDM) to probe the material properties of an in vitro model of processing bodies consisting of out-of-equilibrium condensates formed by the DEAD-box ATPase Dhh1 in the presence of ATP and RNA. By applying this single-droplet technique we show that condensates within the same population exhibit a distribution of material properties, which are regulated on several levels. Removal of the low-complexity domains (LCDs) of the protein decreases the fluidity of the condensates. Structured RNA leads to a larger fraction of dynamically arrested condensates with respect to unstructured polyuridylic acid (polyU). Promotion of the enzymatic ATPase activity of Dhh1 reduces aging of the condensates and the formation of arrested structures, indicating that biochemical activity and material turnover can maintain fluid-like properties over time.
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Affiliation(s)
- Miriam Linsenmeier
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland
| | - Maria Hondele
- Department of Biology, Institute for Biochemistry, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland
- Biozentrum, Center for Molecular Life Sciences, University of Basel, 4056, Basel, Switzerland
| | - Fulvio Grigolato
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland
| | - Eleonora Secchi
- Department of Civil, Environmental and Geomatic Engineering, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland
| | - Karsten Weis
- Department of Biology, Institute for Biochemistry, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland.
| | - Paolo Arosio
- Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, Swiss Federal Institute of Technology, 8093, Zurich, Switzerland.
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46
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Cubuk J, Soranno A. Macromolecular crowding and intrinsically disordered proteins: a polymer physics perspective. CHEMSYSTEMSCHEM 2022. [DOI: 10.1002/syst.202100051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jasmine Cubuk
- Washington University in St Louis Biochemistry and Molecular Biophysics UNITED STATES
| | - Andrea Soranno
- Washington University in St Louis Biochemistry and Molecular Biophysics 660 St Euclid Ave 63110 St Louis UNITED STATES
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47
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Naullage PM, Haghighatlari M, Namini A, Teixeira JMC, Li J, Zhang O, Gradinaru CC, Forman-Kay JD, Head-Gordon T. Protein Dynamics to Define and Refine Disordered Protein Ensembles. J Phys Chem B 2022; 126:1885-1894. [PMID: 35213160 PMCID: PMC10122607 DOI: 10.1021/acs.jpcb.1c10925] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intrinsically disordered proteins and unfolded proteins have fluctuating conformational ensembles that are fundamental to their biological function and impact protein folding, stability, and misfolding. Despite the importance of protein dynamics and conformational sampling, time-dependent data types are not fully exploited when defining and refining disordered protein ensembles. Here we introduce a computational framework using an elastic network model and normal-mode displacements to generate a dynamic disordered ensemble consistent with NMR-derived dynamics parameters, including transverse R2 relaxation rates and Lipari-Szabo order parameters (S2 values). We illustrate our approach using the unfolded state of the drkN SH3 domain to show that the dynamical ensembles give better agreement than a static ensemble for a wide range of experimental validation data including NMR chemical shifts, J-couplings, nuclear Overhauser effects, paramagnetic relaxation enhancements, residual dipolar couplings, hydrodynamic radii, single-molecule fluorescence Förster resonance energy transfer, and small-angle X-ray scattering.
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Affiliation(s)
- Pavithra M Naullage
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Mojtaba Haghighatlari
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Ashley Namini
- Molecular Medicine Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - João M C Teixeira
- Molecular Medicine Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Jie Li
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Oufan Zhang
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Claudiu C Gradinaru
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Julie D Forman-Kay
- Molecular Medicine Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Teresa Head-Gordon
- Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
- Department of Bioengineering, University of California, Berkeley, California 94720, United States
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48
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How Glutamate Promotes Liquid-liquid Phase Separation and DNA Binding Cooperativity of E. coli SSB Protein. J Mol Biol 2022; 434:167562. [PMID: 35351518 PMCID: PMC9400470 DOI: 10.1016/j.jmb.2022.167562] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 01/01/2023]
Abstract
E. coli single-stranded-DNA binding protein (EcSSB) displays nearest-neighbor (NN) and non-nearest-neighbor (NNN)) cooperativity in binding ssDNA during genome maintenance. NNN cooperativity requires the intrinsically-disordered linkers (IDL) of the C-terminal tails. Potassium glutamate (KGlu), the primary E. coli salt, promotes NNN-cooperativity, while KCl inhibits it. We find that KGlu promotes compaction of a single polymeric SSB-coated ssDNA beyond what occurs in KCl, indicating a link of compaction to NNN-cooperativity. EcSSB also undergoes liquid-liquid phase separation (LLPS), inhibited by ssDNA binding. We find that LLPS, like NNN-cooperativity, is promoted by increasing [KGlu] in the physiological range, while increasing [KCl] and/or deletion of the IDL eliminate LLPS, indicating similar interactions in both processes. From quantitative determinations of interactions of KGlu and KCl with protein model compounds, we deduce that the opposing effects of KGlu and KCl on SSB LLPS and cooperativity arise from their opposite interactions with amide groups. KGlu interacts unfavorably with the backbone (especially Gly) and side chain amide groups of the IDL, promoting amide-amide interactions in LLPS and NNN-cooperativity. By contrast, KCl interacts favorably with these amide groups and therefore inhibits LLPS and NNN-cooperativity. These results highlight the importance of salt interactions in regulating the propensity of proteins to undergo LLPS.
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49
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Shin Y. Rich Phase Separation Behavior of Biomolecules. Mol Cells 2022; 45:6-15. [PMID: 34966005 PMCID: PMC8819493 DOI: 10.14348/molcells.2021.0204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/10/2021] [Accepted: 09/10/2021] [Indexed: 11/27/2022] Open
Abstract
Phase separation is a thermodynamic process leading to the formation of compositionally distinct phases. For the past few years, numerous works have shown that biomolecular phase separation serves as biogenesis mechanisms of diverse intracellular condensates, and aberrant phase transitions are associated with disease states such as neurodegenerative diseases and cancers. Condensates exhibit rich phase behaviors including multiphase internal structuring, noise buffering, and compositional tunability. Recent studies have begun to uncover how a network of intermolecular interactions can give rise to various biophysical features of condensates. Here, we review phase behaviors of biomolecules, particularly with regard to regular solution models of binary and ternary mixtures. We discuss how these theoretical frameworks explain many aspects of the assembly, composition, and miscibility of diverse biomolecular phases, and highlight how a model-based approach can help elucidate the detailed thermodynamic principle for multicomponent intracellular phase separation.
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Affiliation(s)
- Yongdae Shin
- Department of Mechanical Engineering, Seoul National University, Seoul 08826, Korea
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul 08826, Korea
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50
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Yeast cells actively tune their membranes to phase separate at temperatures that scale with growth temperatures. Proc Natl Acad Sci U S A 2022; 119:2116007119. [PMID: 35046036 PMCID: PMC8795566 DOI: 10.1073/pnas.2116007119] [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: 12/06/2021] [Indexed: 02/06/2023] Open
Abstract
Phase separation in membranes creates domains enriched in specific components. To date, the best example of micrometer-scale phase separation in the membrane of an unperturbed, living cell occurs in a yeast (Saccharomyces cerevisiae) organelle called the vacuole. Recent studies indicate that the phases are functionally important, enabling yeast survival during periods of stress. We discovered that yeast regulate this phase transition; the temperature at which membrane components mix into a single phase is ∼15 °C above the growth temperature. To maintain this offset, yeast may tune the level of ergosterol (a molecule that is structurally similar to cholesterol) in their membranes. Surprisingly, depleting sterols in vacuole membranes causes them to phase separate, in contrast to previous assumptions. Membranes of vacuoles, the lysosomal organelles of Saccharomyces cerevisiae (budding yeast), undergo extraordinary changes during the cell’s normal growth cycle. The cycle begins with a stage of rapid cell growth. Then, as glucose becomes scarce, growth slows, and vacuole membranes phase separate into micrometer-scale domains of two liquid phases. Recent studies suggest that these domains promote yeast survival by organizing membrane proteins that play key roles in a central signaling pathway conserved among eukaryotes (TORC1). An outstanding question in the field has been whether cells regulate phase transitions in response to new physical conditions and how this occurs. Here, we measure transition temperatures and find that after an increase of roughly 15 °C, vacuole membranes appear uniform, independent of growth temperature. Moreover, populations of cells grown at a single temperature regulate this transition to occur over a surprisingly narrow temperature range. Remarkably, the transition temperature scales linearly with the growth temperature, demonstrating that the cells physiologically adapt to maintain proximity to the transition. Next, we ask how yeast adjust their membranes to achieve phase separation. We isolate vacuoles from yeast during the rapid stage of growth, when their membranes do not natively exhibit domains. Ergosterol is the major sterol in yeast. We find that domains appear when ergosterol is depleted, contradicting the prevalent assumption that increases in sterol concentration generally cause membrane phase separation in vivo, but in agreement with previous studies using artificial and cell-derived membranes.
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