1
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De Luca G, Sancataldo G, Militello B, Vetri V. Surface-catalyzed liquid-liquid phase separation and amyloid-like assembly in microscale compartments. J Colloid Interface Sci 2024; 676:569-581. [PMID: 39053405 DOI: 10.1016/j.jcis.2024.07.135] [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: 04/19/2024] [Revised: 06/24/2024] [Accepted: 07/16/2024] [Indexed: 07/27/2024]
Abstract
Liquid-liquid phase separation is a key phenomenon in the formation of membrane-less structures within the cell, appearing as liquid biomolecular condensates. Protein condensates are the most studied for their biological relevance, and their tendency to evolve, resulting in the formation of aggregates with a high level of order called amyloid. In this study, it is demonstrated that Human Insulin forms micrometric, round amyloid-like structures at room temperature within sub-microliter scale aqueous compartments. These distinctive particles feature a solid core enveloped by a fluid-like corona and form at the interface between the aqueous compartment and the glass coverslip upon which they are cast. Quantitative fluorescence microscopy is used to study in real-time the formation of amyloid-like superstructures. Their formation results driven by liquid-liquid phase separation process that arises from spatially heterogeneous distribution of nuclei at the glass-water interface. The proposed experimental setup allows modifying the surface-to-volume ratio of the aqueous compartments, which affects the aggregation rate and particle size, while also inducing fine alterations in the molecular structures of the final assemblies. These findings enhance the understanding of the factors governing amyloid structure formation, shedding light on the catalytic role of surfaces in this process.
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Affiliation(s)
- Giuseppe De Luca
- Department Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze, 16, 90128, Palermo, Italy; Department of Physics and Chemistry - Emilio Segrè, University of Palermo, Viale delle Scienze, 18, 90128, Palermo, Italy.
| | - Giuseppe Sancataldo
- Department of Physics and Chemistry - Emilio Segrè, University of Palermo, Viale delle Scienze, 18, 90128, Palermo, Italy.
| | - Benedetto Militello
- Department of Physics and Chemistry - Emilio Segrè, University of Palermo, Viale delle Scienze, 18, 90128, Palermo, Italy; INFN Sezione di Catania, Via Santa Sofia 64, 95123 Catania, Italy.
| | - Valeria Vetri
- Department of Physics and Chemistry - Emilio Segrè, University of Palermo, Viale delle Scienze, 18, 90128, Palermo, Italy.
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2
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Monsen RC, Sabo TM, Gray R, Hopkins JB, Chaires JB. Early Events in G-quadruplex Folding Captured by Time-Resolved Small-Angle X-Ray Scattering. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.05.611539. [PMID: 39282441 PMCID: PMC11398465 DOI: 10.1101/2024.09.05.611539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/20/2024]
Abstract
Time-resolved small-angle X-ray experiments (TR-SAXS) are reported here that capture and quantify a previously unknown rapid collapse of the unfolded oligonucleotide as an early step in G4 folding of hybrid 1 and hybrid 2 telomeric G-quadruplex structures. The rapid collapse, initiated by a pH jump, is characterized by an exponential decrease in the radius of gyration from 20.6 to 12.6 Å. The collapse is monophasic and is complete in less than 600 ms. Additional hand-mixing pH-jump kinetic studies show that slower kinetic steps follow the collapse. The folded and unfolded states at equilibrium were further characterized by SAXS studies and other biophysical tools, to show that G4 unfolding was complete at alkaline pH, but not in LiCl solution as is often claimed. The SAXS Ensemble Optimization Method (EOM) analysis reveals models of the unfolded state as a dynamic ensemble of flexible oligonucleotide chains with a variety of transient hairpin structures. These results suggest a G4 folding pathway in which a rapid collapse, analogous to molten globule formation seen in proteins, is followed by a confined conformational search within the collapsed particle to form the native contacts ultimately found in the stable folded form.
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Affiliation(s)
- Robert C Monsen
- Department of Medicine, UofL Health Brown Cancer Center, University of Louisville, Louisville KY, 505 S Hancock St, Louisville, KY 40202
| | - T Michael Sabo
- Department of Medicine, UofL Health Brown Cancer Center, University of Louisville, Louisville KY, 505 S Hancock St, Louisville, KY 40202
| | - Robert Gray
- Department of Medicine, UofL Health Brown Cancer Center, University of Louisville, Louisville KY, 505 S Hancock St, Louisville, KY 40202
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT) Department of Physics, Illinois Institute of Technology, Chicago, IL 60616
| | - Jonathan B Chaires
- Department of Medicine, UofL Health Brown Cancer Center, University of Louisville, Louisville KY, 505 S Hancock St, Louisville, KY 40202
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3
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Zhang G, Chu X. Balancing thermodynamic stability, dynamics, and kinetics in phase separation of intrinsically disordered proteins. J Chem Phys 2024; 161:095102. [PMID: 39225535 DOI: 10.1063/5.0220861] [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: 05/29/2024] [Accepted: 07/25/2024] [Indexed: 09/04/2024] Open
Abstract
Intrinsically disordered proteins (IDPs) are prevalent participants in liquid-liquid phase separation due to their inherent potential for promoting multivalent binding. Understanding the underlying mechanisms of phase separation is challenging, as phase separation is a complex process, involving numerous molecules and various types of interactions. Here, we used a simplified coarse-grained model of IDPs to investigate the thermodynamic stability of the dense phase, conformational properties of IDPs, chain dynamics, and kinetic rates of forming condensates. We focused on the IDP system, in which the oppositely charged IDPs are maximally segregated, inherently possessing a high propensity for phase separation. By varying interaction strengths, salt concentrations, and temperatures, we observed that IDPs in the dense phase exhibited highly conserved conformational characteristics, which are more extended than those in the dilute phase. Although the chain motions and global conformational dynamics of IDPs in the condensates are slow due to the high viscosity, local chain flexibility at the short timescales is largely preserved with respect to that at the free state. Strikingly, we observed a non-monotonic relationship between interaction strengths and kinetic rates for forming condensates. As strong interactions of IDPs result in high stable condensates, our results suggest that the thermodynamics and kinetics of phase separation are decoupled and optimized by the speed-stability balance through underlying molecular interactions. Our findings contribute to the molecular-level understanding of phase separation and offer valuable insights into the developments of engineering strategies for precise regulation of biomolecular condensates.
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Affiliation(s)
- Guoqing Zhang
- Advanced Materials Thrust, Function Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, Guangdong 511400, China
| | - Xiakun Chu
- Advanced Materials Thrust, Function Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, Guangdong 511400, China
- Guangzhou Municipal Key Laboratory of Materials Informatics, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, Guangdong 511400, China
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR 999077, China
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4
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Nakada M, Kanda J, Uchiyama H, Matsumura K. Nanoscale intracellular ultrastructures affected by osmotic pressure using small-angle X-ray scattering. Biophys Chem 2024; 312:107287. [PMID: 38981174 DOI: 10.1016/j.bpc.2024.107287] [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: 05/12/2024] [Revised: 06/12/2024] [Accepted: 06/26/2024] [Indexed: 07/11/2024]
Abstract
Although intracellular ultrastructures have typically been studied using microscopic techniques, it is difficult to observe ultrastructures at the submicron scale of living cells due to spatial resolution (fluorescence microscopy) or high vacuum environment (electron microscopy). We investigate the nanometer scale intracellular ultrastructures of living CHO cells in various osmolality using small-angle X-ray scattering (SAXS), and especially the structures of ribosomes, DNA double helix, and plasma membranes in-cell environment are observed. Ribosomes expand and contract in response to osmotic pressure, and the inter-ribosomal correlation occurs under isotonic and hyperosmolality. The DNA double helix is not dependent on the osmotic pressure. Under high osmotic pressure, the plasma membrane folds into form a multilamellar structure with a periodic length of about 6 nm. We also study the ultrastructural changes caused by formaldehyde fixation, freezing and heating.
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Affiliation(s)
- Masaru Nakada
- Toray Research Center, Inc., 2-11 Sonoyama 3-chome, Otsu, Shiga 520-8567, Japan.
| | - Junko Kanda
- Toray Research Center, Inc., 2-11 Sonoyama 3-chome, Otsu, Shiga 520-8567, Japan
| | - Hironobu Uchiyama
- Toray Research Center, Inc., 2-11 Sonoyama 3-chome, Otsu, Shiga 520-8567, Japan
| | - Kazuaki Matsumura
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
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5
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Pradhan S, Campanile M, Sharma S, Oliva R, Patra S. Mechanistic Insights into the c-MYC G-Quadruplex and Berberine Binding inside an Aqueous Two-Phase System Mimicking Biomolecular Condensates. J Phys Chem Lett 2024; 15:8706-8714. [PMID: 39159468 DOI: 10.1021/acs.jpclett.4c01806] [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: 08/21/2024]
Abstract
We investigated the binding between the c-MYC G-quadruplex (GQ) and berberine chloride (BCl) in an aqueous two-phase system (ATPS) with 12.3 wt % polyethylene glycol and 5.6 wt % dextran, mimicking the highly crowded intracellular biomolecular condensates formed via liquid-liquid phase separation. We found that in the ATPS, complex formation is significantly altered, leading to an increase in affinity and a change in the stoichiometry of the complex with respect to neat buffer conditions. Thermodynamic studies reveal that binding becomes more thermodynamically favorable in the ATPS due to entropic effects, as the strong excluded volume effect inside ATPS droplets reduces the entropic penalty associated with binding. Finally, the binding affinity of BCl for the c-MYC GQ is higher than those for other DNA structures, indicating potential specific interactions. Overall, these findings will be helpful in the design of potential drugs targeting the c-MYC GQ structures in cancer-related biocondensates.
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Affiliation(s)
- Susmita Pradhan
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Pilani Campus, Pilani 333031, Rajasthan, India
| | - Marco Campanile
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 26, 80126 Naples, Italy
| | - Shubhangi Sharma
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Pilani Campus, Pilani 333031, Rajasthan, India
| | - Rosario Oliva
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia, 26, 80126 Naples, Italy
| | - Satyajit Patra
- Department of Chemistry, Birla Institute of Technology and Science-Pilani, Pilani Campus, Pilani 333031, Rajasthan, India
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6
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Niu Z, Gui X, Feng S, Reif B. Aggregation Mechanisms and Molecular Structures of Amyloid-β in Alzheimer's Disease. Chemistry 2024; 30:e202400277. [PMID: 38888453 DOI: 10.1002/chem.202400277] [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: 01/22/2024] [Revised: 06/13/2024] [Accepted: 06/17/2024] [Indexed: 06/20/2024]
Abstract
Amyloid plaques are a major pathological hallmark involved in Alzheimer's disease and consist of deposits of the amyloid-β peptide (Aβ). The aggregation process of Aβ is highly complex, which leads to polymorphous aggregates with different structures. In addition to aberrant aggregation, Aβ oligomers can undergo liquid-liquid phase separation (LLPS) and form dynamic condensates. It has been hypothesized that these amyloid liquid droplets affect and modulate amyloid fibril formation. In this review, we briefly introduce the relationship between stress granules and amyloid protein aggregation that is associated with neurodegenerative diseases. Then we highlight the regulatory role of LLPS in Aβ aggregation and discuss the potential relationship between Aβ phase transition and aggregation. Furthermore, we summarize the current structures of Aβ oligomers and amyloid fibrils, which have been determined using nuclear magnetic resonance (NMR) and cryo-electron microscopy (cryo-EM). The structural variations of Aβ aggregates provide an explanation for the different levels of toxicity, shed light on the aggregation mechanism and may pave the way towards structure-based drug design for both clinical diagnosis and treatment.
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Affiliation(s)
- Zheng Niu
- School of Pharmacy, Henan University, Kaifeng, Henan, 475004, China
| | - Xinrui Gui
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Shuang Feng
- School of Pharmacy, Henan University, Kaifeng, Henan, 475004, China
| | - Bernd Reif
- Bavarian NMR Center (B NMRZ), Department of Bioscience, TUM School of Natural Sciences, Technische Universität München (TUM), Garching, 85747, Germany
- Institute of Structural Biology (STB), Helmholtz-Zentrum, München (HMGU), Neuherberg, 85764, Germany
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7
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Aplin C, Zielinski KA, Pabit S, Ogunribido D, Katt WP, Pollack L, Cerione RA, Milano SK. Distinct conformational states enable transglutaminase 2 to promote cancer cell survival versus cell death. Commun Biol 2024; 7:982. [PMID: 39134806 PMCID: PMC11319651 DOI: 10.1038/s42003-024-06672-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 08/02/2024] [Indexed: 08/15/2024] Open
Abstract
Transglutaminase 2 (TG2) is a GTP-binding, protein-crosslinking enzyme that has been investigated as a therapeutic target for Celiac disease, neurological disorders, and aggressive cancers. TG2 has been suggested to adopt two conformational states that regulate its functions: a GTP-bound, closed conformation, and a calcium-bound, crosslinking-active open conformation. TG2 mutants that constitutively adopt an open conformation are cytotoxic to cancer cells. Thus, small molecules that bind and stabilize the open conformation of TG2 could offer a new therapeutic strategy. Here, we investigate TG2, using static and time-resolved small-angle X-ray scattering (SAXS) and single-particle cryoelectron microscopy (cryo-EM), to determine the conformational states responsible for conferring its biological effects. We also describe a newly developed TG2 inhibitor, LM11, that potently kills glioblastoma cells and use SAXS to investigate how LM11 affects the conformational states of TG2. Using SAXS and cryo-EM, we show that guanine nucleotides bind and stabilize a monomeric closed conformation while calcium binds to an open state that can form higher order oligomers. SAXS analysis suggests how a TG2 mutant that constitutively adopts the open state binds nucleotides through an alternative mechanism to wildtype TG2. Furthermore, we use time resolved SAXS to show that LM11 increases the ability of calcium to bind and stabilize an open conformation, which is not reversible by guanine nucleotides and is cytotoxic to cancer cells. Taken together, our findings demonstrate that the conformational dynamics of TG2 are more complex than previously suggested and highlight how conformational stabilization of TG2 by LM11 maintains TG2 in a cytotoxic conformational state.
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Affiliation(s)
- Cody Aplin
- Department of Chemistry and Chemical Biology, Cornell University, 14853, Ithaca, NY, USA
- Department of Molecular Medicine, Cornell University, 14853, Ithaca, NY, USA
| | - Kara A Zielinski
- School of Applied and Engineering Physics, Cornell University, 14853, Ithaca, NY, USA
| | - Suzette Pabit
- School of Applied and Engineering Physics, Cornell University, 14853, Ithaca, NY, USA
| | - Deborah Ogunribido
- Department of Chemistry and Chemical Biology, Cornell University, 14853, Ithaca, NY, USA
| | - William P Katt
- Department of Molecular Medicine, Cornell University, 14853, Ithaca, NY, USA
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, 14853, Ithaca, NY, USA
| | - Richard A Cerione
- Department of Chemistry and Chemical Biology, Cornell University, 14853, Ithaca, NY, USA.
- Department of Molecular Medicine, Cornell University, 14853, Ithaca, NY, USA.
| | - Shawn K Milano
- Department of Chemistry and Chemical Biology, Cornell University, 14853, Ithaca, NY, USA
- Department of Molecular Medicine, Cornell University, 14853, Ithaca, NY, USA
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8
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Koch L, Pollak R, Ebbinghaus S, Huber K. Early Stages of FUS Droplet Formation via Liquid-Liquid Phase Separation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:16151-16159. [PMID: 39069878 DOI: 10.1021/acs.langmuir.4c01243] [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
The phase behavior of complex biomolecular solutions may explain different cellular processes, including the organization of cells by membraneless organelles. The early stages of phase separation are crucial to understanding the underlying mechanism and identifying biomolecules that trigger or drive the transition. Here, we analyze the early events of liquid-liquid phase separation (LLPS) of FUS by multiangle time-resolved static and dynamic light scattering. LLPS was triggered by TEV-catalyzed cleavage of the MBP-tag from FUS-MBP. The light scattering measurements revealed the existence of at least two fractions of FUS-MBP aggregates already prior to the onset of LLPS. The orders of magnitude of the aggregate size in these two fractions are 10 and 100 nm, respectively. LLPS started after an induction period, which depended on the concentration of FUS-MBP. The data from time-dependent light scattering revealed a coalescence of droplets also denoted as a step growth process. A step growth process instead of nucleation and growth via monomer addition suggests that LLPS takes place within the spinodal rather than between the binodal and the spinodal.
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Affiliation(s)
- Leon Koch
- Physical Chemistry, University of Paderborn, Warburger Str. 100, Paderborn 33098, Germany
| | - Roland Pollak
- Biophysical Chemistry, Ruhr-University Bochum, Bochum 44780, Germany
- Research Center Chemical Sciences and Sustainability, Research Alliance Ruhr, Universitätsstraße 150, Bochum 44780, Germany
- Physical and Theoretical Chemistry, TU Braunschweig, Rebenring 56, Braunschweig 38106, Germany
| | - Simon Ebbinghaus
- Biophysical Chemistry, Ruhr-University Bochum, Bochum 44780, Germany
- Research Center Chemical Sciences and Sustainability, Research Alliance Ruhr, Universitätsstraße 150, Bochum 44780, Germany
- Physical and Theoretical Chemistry, TU Braunschweig, Rebenring 56, Braunschweig 38106, Germany
| | - Klaus Huber
- Physical Chemistry, University of Paderborn, Warburger Str. 100, Paderborn 33098, Germany
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Fujii K, Izumi Y, Maita N, Matsuo K, Kato M. Observation of the Liquid-Liquid Phase Separation of FUS-LC Using Vacuum-Ultraviolet Circular Dichroism Spectroscopy. Chirality 2024; 36:e23707. [PMID: 39129227 DOI: 10.1002/chir.23707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 07/03/2024] [Accepted: 07/11/2024] [Indexed: 08/13/2024]
Abstract
To reveal the structural mechanism by which the low-complexity domain of the fused in sarcoma protein (FUS-LC) mediates liquid-liquid phase separation (LLPS), we conducted a vacuum-ultraviolet circular dichroism (VUV-CD) spectroscopic study, a technique to analyze the secondary structures of proteins. The VUV-CD measurements were performed at the BL12 VUV-CD station at the Hiroshima Synchrotron Radiation Center (HiSOR) in Japan. CD spectra were measured between 180 and 260 nm while controlling the temperature of samples from 37°C to 5°C to obtain the LLPS of FUS-LC. The CD spectrum obtained at 37°C exhibited a large negative peak at 195 nm and a small negative shoulder near 220 nm. The peak intensity around 195 nm decreased as the sample temperature decreased. The spectral changes originated from the LLPS formation.
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Affiliation(s)
- Kentaro Fujii
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Yudai Izumi
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Nobuo Maita
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Koichi Matsuo
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Hiroshima, Japan
| | - Masato Kato
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Chiba, Japan
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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10
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Zhou HX, Kota D, Qin S, Prasad R. Fundamental Aspects of Phase-Separated Biomolecular Condensates. Chem Rev 2024; 124:8550-8595. [PMID: 38885177 PMCID: PMC11260227 DOI: 10.1021/acs.chemrev.4c00138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Biomolecular condensates, formed through phase separation, are upending our understanding in much of molecular, cell, and developmental biology. There is an urgent need to elucidate the physicochemical foundations of the behaviors and properties of biomolecular condensates. Here we aim to fill this need by writing a comprehensive, critical, and accessible review on the fundamental aspects of phase-separated biomolecular condensates. We introduce the relevant theoretical background, present the theoretical basis for the computation and experimental measurement of condensate properties, and give mechanistic interpretations of condensate behaviors and properties in terms of interactions at the molecular and residue levels.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
- Department of Physics, University of Illinois Chicago, Chicago, Illinois 60607, USA
| | - Divya Kota
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
| | - Sanbo Qin
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
| | - Ramesh Prasad
- Department of Chemistry, University of Illinois Chicago, Chicago, Illinois 60607, USA
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11
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Tsoi PS, Ferreon JC, Ferreon ACM. Initiation of hnRNPA1 Low-Complexity Domain Condensation Monitored by Dynamic Light Scattering. Int J Mol Sci 2024; 25:6825. [PMID: 38999934 PMCID: PMC11241569 DOI: 10.3390/ijms25136825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/14/2024] [Accepted: 06/18/2024] [Indexed: 07/14/2024] Open
Abstract
Biomolecular condensates (BMCs) exhibit physiological and pathological relevance in biological systems. Both liquid and solid condensates play significant roles in the spatiotemporal regulation and organization of macromolecules and their biological activities. Some pathological solid condensates, such as Lewy Bodies and other fibrillar aggregates, have been hypothesized to originate from liquid condensates. With the prevalence of BMCs having functional and dysfunctional roles, it is imperative to understand the mechanism of biomolecular condensate formation and initiation. Using the low-complexity domain (LCD) of heterogenous ribonuclear protein A1 (hnRNPA1) as our model, we monitored initial assembly events using dynamic light scattering (DLS) while modulating pH and salt conditions to perturb macromolecule and condensate properties. We observed the formation of nanometer-sized BMCs (nano-condensates) distinct from protein monomers and micron-sized condensates. We also observed that conditions that solubilize micron-sized protein condensates do not solubilize nano-condensates, indicating that the balance of forces that stabilize nano-condensates and micron-sized condensates are distinct. These findings provide insight into the forces that drive protein phase separation and potential nucleation structures of macromolecular condensation.
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Affiliation(s)
| | - Josephine C. Ferreon
- Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Allan Chris M. Ferreon
- Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA
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Mitra R, Usher ET, Dedeoğlu S, Crotteau MJ, Fraser OA, Yennawar NH, Gadkari VV, Ruotolo BT, Holehouse AS, Salmon L, Showalter SA, Bardwell JCA. Molecular insights into the interaction between a disordered protein and a folded RNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.12.598678. [PMID: 38915483 PMCID: PMC11195163 DOI: 10.1101/2024.06.12.598678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Intrinsically disordered protein regions (IDRs) are well-established as contributors to intermolecular interactions and the formation of biomolecular condensates. In particular, RNA-binding proteins (RBPs) often harbor IDRs in addition to folded RNA-binding domains that contribute to RBP function. To understand the dynamic interactions of an IDR-RNA complex, we characterized the RNA-binding features of a small (68 residues), positively charged IDR-containing protein, SERF. At high concentrations, SERF and RNA undergo charge-driven associative phase separation to form a protein- and RNA-rich dense phase. A key advantage of this model system is that this threshold for demixing is sufficiently high that we could use solution-state biophysical methods to interrogate the stoichiometric complexes of SERF with RNA in the one-phase regime. Herein, we describe our comprehensive characterization of SERF alone and in complex with a small fragment of the HIV-1 TAR RNA (TAR) with complementary biophysical methods and molecular simulations. We find that this binding event is not accompanied by the acquisition of structure by either molecule; however, we see evidence for a modest global compaction of the SERF ensemble when bound to RNA. This behavior likely reflects attenuated charge repulsion within SERF via binding to the polyanionic RNA and provides a rationale for the higher-order assembly of SERF in the context of RNA. We envision that the SERF-RNA system will lower the barrier to accessing the details that support IDR-RNA interactions and likewise deepen our understanding of the role of IDR-RNA contacts in complex formation and liquid-liquid phase separation.
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Affiliation(s)
- Rishav Mitra
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Emery T. Usher
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO, USA
| | - Selin Dedeoğlu
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs, (CRMN), UMR 5082, CNRS, ENS Lyon, UCBL, Université de Lyon, 69100 Villeurbanne, France
| | - Matthew J. Crotteau
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Olivia A. Fraser
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Neela H. Yennawar
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Varun V. Gadkari
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Brandon T. Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Alex S. Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO, USA
| | - Loïc Salmon
- Centre de Résonance Magnétique Nucléaire à Très Hauts Champs, (CRMN), UMR 5082, CNRS, ENS Lyon, UCBL, Université de Lyon, 69100 Villeurbanne, France
| | - Scott A. Showalter
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - James C. A. Bardwell
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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13
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Qian K, Stella L, Liu F, Jones DS, Andrews GP, Tian Y. Kinetic and Thermodynamic Interplay of Polymer-Mediated Liquid-Liquid Phase Separation for Poorly Water-Soluble Drugs. Mol Pharm 2024; 21:2878-2893. [PMID: 38767457 DOI: 10.1021/acs.molpharmaceut.4c00033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Understanding the interplay between kinetics and thermodynamics of polymer-mediated liquid-liquid phase separation is crucial for designing and implementing an amorphous solid dispersion formulation strategy for poorly water-soluble drugs. This work investigates the phase behaviors of a poorly water-soluble model drug, celecoxib (CXB), in a supersaturated aqueous solution with and without polymeric additives (PVP, PVPVA, HPMCAS, and HPMCP). Drug-polymer-water ternary phase diagrams were also constructed to estimate the thermodynamic behaviors of the mixtures at room temperature. The liquid-liquid phase separation onset point for CXB was detected using an inline UV/vis spectrometer equipped with a fiber optic probe. Varying CXB concentrations were achieved using an accurate syringe pump throughout this study. The appearance of the transient nanodroplets was verified by cryo-EM and total internal reflection fluoresence microscopic techniques. The impacts of various factors, such as polymer composition, drug stock solution pumping rates, and the types of drug-polymer interactions, are tested against the onset points of the CXB liquid-liquid phase separation (LLPS). It was found that the types of drug-polymer interactions, i.e., hydrogen bonding and hydrophobic interactions, are vital to the position and shapes of LLPS in the supersaturation drug solution. A relation between the behaviors of LLPS and its location in the CXB-polymer-water ternary phase diagram was drawn from the findings.
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Affiliation(s)
- Kaijie Qian
- School of Pharmacy, McClay Research Centre, Queen's University Belfast, 97 Lisburn Road, Northern Ireland BT9 7BL, U.K
| | - Lorenzo Stella
- School of Mathematics and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, U.K
- School of Chemistry and Chemical Engineering, Queen's University Belfast, Stranmillis Road, Belfast BT9 5AG, U.K
| | - Fanjun Liu
- School of Pharmacy, McClay Research Centre, Queen's University Belfast, 97 Lisburn Road, Northern Ireland BT9 7BL, U.K
| | - David S Jones
- School of Pharmacy, McClay Research Centre, Queen's University Belfast, 97 Lisburn Road, Northern Ireland BT9 7BL, U.K
| | - Gavin P Andrews
- School of Pharmacy, McClay Research Centre, Queen's University Belfast, 97 Lisburn Road, Northern Ireland BT9 7BL, U.K
| | - Yiwei Tian
- School of Pharmacy, McClay Research Centre, Queen's University Belfast, 97 Lisburn Road, Northern Ireland BT9 7BL, U.K
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14
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Hong L, Zhang Z, Wang Z, Yu X, Zhang J. Phase separation provides a mechanism to drive phenotype switching. Phys Rev E 2024; 109:064414. [PMID: 39021038 DOI: 10.1103/physreve.109.064414] [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: 03/18/2024] [Accepted: 06/05/2024] [Indexed: 07/20/2024]
Abstract
Phenotypic switching plays a crucial role in cell fate determination across various organisms. Recent experimental findings highlight the significance of protein compartmentalization via liquid-liquid phase separation in influencing such decisions. However, the precise mechanism through which phase separation regulates phenotypic switching remains elusive. To investigate this, we established a mathematical model that couples a phase separation process and a gene expression process with feedback. We used the chemical master equation theory and mean-field approximation to study the effects of phase separation on the gene expression products. We found that phase separation can cause bistability and bimodality. Furthermore, phase separation can control the bistable properties of the system, such as bifurcation points and bistable ranges. On the other hand, in stochastic dynamics, the droplet phase exhibits double peaks within a more extensive phase separation threshold range than the dilute phase, indicating the pivotal role of the droplet phase in cell fate decisions. These findings propose an alternative mechanism that influences cell fate decisions through the phase separation process. As phase separation is increasingly discovered in gene regulatory networks, related modeling research can help build biomolecular systems with desired properties and offer insights into explaining cell fate decisions.
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15
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Mukherjee S, Poudyal M, Dave K, Kadu P, Maji SK. Protein misfolding and amyloid nucleation through liquid-liquid phase separation. Chem Soc Rev 2024; 53:4976-5013. [PMID: 38597222 DOI: 10.1039/d3cs01065a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Liquid-liquid phase separation (LLPS) is an emerging phenomenon in cell physiology and diseases. The weak multivalent interaction prerequisite for LLPS is believed to be facilitated through intrinsically disordered regions, which are prevalent in neurodegenerative disease-associated proteins. These aggregation-prone proteins also exhibit an inherent property for phase separation, resulting in protein-rich liquid-like droplets. The very high local protein concentration in the water-deficient confined microenvironment not only drives the viscoelastic transition from the liquid to solid-like state but also most often nucleate amyloid fibril formation. Indeed, protein misfolding, oligomerization, and amyloid aggregation are observed to be initiated from the LLPS of various neurodegeneration-related proteins. Moreover, in these cases, neurodegeneration-promoting genetic and environmental factors play a direct role in amyloid aggregation preceded by the phase separation. These cumulative recent observations ignite the possibility of LLPS being a prominent nucleation mechanism associated with aberrant protein aggregation. The present review elaborates on the nucleation mechanism of the amyloid aggregation pathway and the possible early molecular events associated with amyloid-related protein phase separation. It also summarizes the recent advancement in understanding the aberrant phase transition of major proteins contributing to neurodegeneration focusing on the common disease-associated factors. Overall, this review proposes a generic LLPS-mediated multistep nucleation mechanism for amyloid aggregation and its implication in neurodegeneration.
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Affiliation(s)
- Semanti Mukherjee
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Manisha Poudyal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Kritika Dave
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Pradeep Kadu
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Samir K Maji
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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16
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Du J, Kim K, Chen M. Distinguishing individual photobodies using Oligopaints reveals thermo-sensitive and -insensitive phytochrome B condensation at distinct subnuclear locations. Nat Commun 2024; 15:3620. [PMID: 38684657 PMCID: PMC11058242 DOI: 10.1038/s41467-024-47789-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 04/10/2024] [Indexed: 05/02/2024] Open
Abstract
Photobodies (PBs) are membraneless subnuclear organelles that self-assemble via concentration-dependent liquid-liquid phase separation (LLPS) of the plant photoreceptor and thermosensor phytochrome B (PHYB). The current PHYB LLPS model posits that PHYB phase separates randomly in the nucleoplasm regardless of the cellular or nuclear context. Here, we established a robust Oligopaints method in Arabidopsis to determine the positioning of individual PBs. We show surprisingly that even in PHYB overexpression lines - where PHYB condensation would be more likely to occur randomly - PBs positioned at twelve distinct subnuclear locations distinguishable by chromocenter and nucleolus landmarks, suggesting that PHYB condensation occurs nonrandomly at preferred seeding sites. Intriguingly, warm temperatures reduce PB number by inducing the disappearance of specific thermo-sensitive PBs, demonstrating that individual PBs possess different thermosensitivities. These results reveal a nonrandom PB nucleation model, which provides the framework for the biogenesis of spatially distinct individual PBs with diverse environmental sensitivities within a single plant nucleus.
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Affiliation(s)
- Juan Du
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Keunhwa Kim
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Meng Chen
- Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA.
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17
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Ray S, Buell AK. Emerging experimental methods to study the thermodynamics of biomolecular condensate formation. J Chem Phys 2024; 160:091001. [PMID: 38445729 DOI: 10.1063/5.0190160] [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: 12/04/2023] [Accepted: 02/15/2024] [Indexed: 03/07/2024] Open
Abstract
The formation of biomolecular condensates in vivo is increasingly recognized to underlie a multitude of crucial cellular functions. Furthermore, the evolution of highly dynamic protein condensates into progressively less reversible assemblies is thought to be involved in a variety of disorders, from cancer over neurodegeneration to rare genetic disorders. There is an increasing need for efficient experimental methods to characterize the thermodynamics of condensate formation and that can be used in screening campaigns to identify and rationally design condensate modifying compounds. Theoretical advances in the field are also identifying the key parameters that need to be measured in order to obtain a comprehensive understanding of the underlying interactions and driving forces. Here, we review recent progress in the development of efficient and quantitative experimental methods to study the driving forces behind and the temporal evolution of biomolecular condensates.
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Affiliation(s)
- Soumik Ray
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Alexander K Buell
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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18
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Das T, Zaidi F, Farag M, Ruff KM, Messing J, Taylor JP, Pappu RV, Mittag T. Metastable condensates suppress conversion to amyloid fibrils. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582569. [PMID: 38464104 PMCID: PMC10925303 DOI: 10.1101/2024.02.28.582569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Stress granules form via co-condensation of RNA binding proteins with prion-like low complexity domains (PLCDs) and RNA molecules released by stress-induced polysomal runoff. Homotypic interactions among PLCDs can drive amyloid fibril formation and this is enhanced by ALS-associated mutations. We find that homotypic interactions that drive condensation versus fibril formation are separable for A1-LCD, the PLCD of hnRNPA1. These separable interactions lead to condensates that are metastable versus fibrils that are globally stable. Metastable condensates suppress fibril formation, and ALS-associated mutations enhance fibril formation by weakening condensate metastability. Mutations designed to enhance A1-LCD condensate metastability restore wild-type behaviors of stress granules in cells even when ALS-associated mutations are present. This suggests that fibril formation can be suppressed by enhancing condensate metastability through condensate-driving interactions.
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Affiliation(s)
- Tapojyoti Das
- Department of Structural Biology, St. Jude Children’s Research Hospital; Memphis, TN 38105, USA
| | - Fatima Zaidi
- Department of Structural Biology, St. Jude Children’s Research Hospital; Memphis, TN 38105, USA
| | - Mina Farag
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis; St. Louis, MO 63130, USA
| | - Kiersten M. Ruff
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis; St. Louis, MO 63130, USA
| | - James Messing
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital; Memphis, TN 38105, USA
| | - J. Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital; Memphis, TN 38105, USA
| | - Rohit V. Pappu
- Department of Biomedical Engineering and Center for Biomolecular Condensates, Washington University in St. Louis; St. Louis, MO 63130, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children’s Research Hospital; Memphis, TN 38105, USA
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19
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Aplin C, Zielinski KA, Pabit S, Ogunribido D, Katt WP, Pollack L, Cerione RA, Milano SK. Defining the conformational states that enable transglutaminase 2 to promote cancer cell survival versus cell death. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.04.578794. [PMID: 38370687 PMCID: PMC10871292 DOI: 10.1101/2024.02.04.578794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Transglutaminase 2 (TG2) is a GTP-binding/protein-crosslinking enzyme that has been investigated as a therapeutic target for Celiac disease, neurological disorders, and aggressive cancers. TG2 has been suggested to adopt two conformational states that regulate its functions: a GTP-bound, closed conformation, and a calcium-bound, crosslinking-active open conformation. TG2 mutants that constitutively adopt an open conformation are cytotoxic to cancer cells. Thus, small molecules that maintain the open conformation of TG2 could offer a new therapeutic strategy. Here, we investigate TG2, using static and time-resolved small-angle X-ray scattering (SAXS) and single-particle cryoelectron microscopy (cryo-EM), to determine the conformational states responsible for conferring its biological effects. We also describe a newly developed TG2 inhibitor, LM11, that potently kills glioblastoma cells and use SAXS to investigate how LM11 affects the conformational states of TG2. Using SAXS and cryo-EM, we show that guanine nucleotide-bound TG2 adopts a monomeric closed conformation while calcium-bound TG2 assumes an open conformational state that can form higher order oligomers. SAXS analysis also suggests how a TG2 mutant that constitutively adopts the open state binds nucleotides through an alternative mechanism to wildtype TG2. Furthermore, we use time-resolved SAXS to show that LM11 increases the ability of calcium to drive TG2 to an open conformation, which is not reversible by guanine nucleotides and is cytotoxic to cancer cells. Taken together, our findings demonstrate that the conformational dynamics of TG2 are more complex than previously suggested and highlight how conformational stabilization of TG2 by LM11 maintains TG2 in a cytotoxic conformational state.
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Affiliation(s)
- Cody Aplin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853
| | - Kara A. Zielinski
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853
| | - Suzette Pabit
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853
| | - Deborah Ogunribido
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - William P. Katt
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853
| | - Richard A. Cerione
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853
| | - Shawn K. Milano
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853
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20
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Mohanty P, Rizuan A, Kim YC, Fawzi NL, Mittal J. A complex network of interdomain interactions underlies the conformational ensemble of monomeric TDP-43 and modulates its phase behavior. Protein Sci 2024; 33:e4891. [PMID: 38160320 PMCID: PMC10804676 DOI: 10.1002/pro.4891] [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: 09/06/2023] [Revised: 12/07/2023] [Accepted: 12/28/2023] [Indexed: 01/03/2024]
Abstract
TAR DNA-binding protein 43 (TDP-43) is a multidomain protein involved in the regulation of RNA metabolism, and its aggregates have been observed in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Numerous studies indicate TDP-43 can undergo liquid-liquid phase separation (LLPS) in vitro and is a component of biological condensates. Homo-oligomerization via the folded N-terminal domain (aa:1-77) and the conserved helical region (aa:319-341) of the disordered, C-terminal domain is found to be an important driver of TDP-43 phase separation. However, a comprehensive molecular view of TDP-43 phase separation, particularly regarding the nature of heterodomain interactions, is lacking due to the challenges associated with its stability and purification. Here, we utilize all-atom and coarse-grained (CG) molecular dynamics (MD) simulations to uncover the network of interdomain interactions implicated in TDP-43 phase separation. All-atom simulations uncovered the presence of transient, interdomain interactions involving flexible linkers, RNA-recognition motif (RRM) domains and a charged segment of disordered C-terminal domain (CTD). CG simulations indicate these inter-domain interactions which affect the conformational landscape of TDP-43 in the dilute phase are also prevalent in the condensed phase. Finally, sequence and surface charge distribution analysis coupled with all-atom simulations (at high salt) confirmed that the transient interdomain contacts are predominantly electrostatic in nature. Overall, our findings from multiscale simulations lead to a greater appreciation of the complex interaction network underlying the structural landscape and phase separation of TDP-43.
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Affiliation(s)
- Priyesh Mohanty
- Artie McFerrin Department of Chemical EngineeringTexas A&M UniversityCollege StationTexasUSA
| | - Azamat Rizuan
- Artie McFerrin Department of Chemical EngineeringTexas A&M UniversityCollege StationTexasUSA
| | - Young C. Kim
- Naval Research LaboratoryCenter for Materials Physics and TechnologyWashingtonDistrict of ColumbiaUSA
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology and BiochemistryProvidenceRhode IslandUSA
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical EngineeringTexas A&M UniversityCollege StationTexasUSA
- Department of ChemistryTexas A&M UniversityCollege StationTexasUSA
- Interdisciplinary Graduate Program in Genetics and GenomicsTexas A&M UniversityCollege StationTexasUSA
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21
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Hopkins JB. BioXTAS RAW 2: new developments for a free open-source program for small-angle scattering data reduction and analysis. J Appl Crystallogr 2024; 57:194-208. [PMID: 38322719 PMCID: PMC10840314 DOI: 10.1107/s1600576723011019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/21/2023] [Indexed: 02/08/2024] Open
Abstract
BioXTAS RAW is a free open-source program for reduction, analysis and modelling of biological small-angle scattering data. Here, the new developments in RAW version 2 are described. These include improved data reduction using pyFAI; updated automated Guinier fitting and D max finding algorithms; automated series (e.g. size-exclusion chromatography coupled small-angle X-ray scattering or SEC-SAXS) buffer- and sample-region finding algorithms; linear and integral baseline correction for series; deconvolution of series data using regularized alternating least squares (REGALS); creation of electron-density reconstructions using electron density via solution scattering (DENSS); a comparison window showing residuals, ratios and statistical comparisons between profiles; and generation of PDF reports with summary plots and tables for all analysis. Furthermore, there is now a RAW API, which can be used without the graphical user interface (GUI), providing full access to all of the functionality found in the GUI. In addition to these new capabilities, RAW has undergone significant technical updates, such as adding Python 3 compatibility, and has entirely new documentation available both online and in the program.
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Affiliation(s)
- Jesse B. Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA
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22
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Hopkins JB. BioXTAS RAW 2: new developments for a free open-source program for small angle scattering data reduction and analysis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.25.559353. [PMID: 37808703 PMCID: PMC10557611 DOI: 10.1101/2023.09.25.559353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
BioXTAS RAW is a free, open-source program for reduction, analysis and modelling of biological small angle scattering data. Here, the new developments in RAW version 2 are described. These include: improved data reduction using pyFAI; updated automated Guinier fitting and Dmax finding algorithms; automated series (e.g. SEC-SAXS) buffer and sample region finding algorithms; linear and integral baseline correction for series; deconvolution of series data using REGALS; creation of electron density reconstructions via DENSS; a comparison window showing residuals, ratios, and statistical comparisons between profiles; and generation of PDF reports with summary plots and tables for all analysis. In addition, there is now a RAW API, which can be used without the GUI, providing full access to all of the functionality found in the GUI. In addition to these new capabilities, RAW has undergone significant technical updates, such as adding Python 3 compatibility, and has entirely new documentation available both online and in the program.
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Affiliation(s)
- Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA
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23
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Sahin C, Leppert A, Landreh M. Advances in mass spectrometry to unravel the structure and function of protein condensates. Nat Protoc 2023; 18:3653-3661. [PMID: 37907762 DOI: 10.1038/s41596-023-00900-0] [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: 04/18/2023] [Accepted: 08/09/2023] [Indexed: 11/02/2023]
Abstract
Membrane-less organelles assemble through liquid-liquid phase separation (LLPS) of partially disordered proteins into highly specialized microenvironments. Currently, it is challenging to obtain a clear understanding of the relationship between the structure and function of phase-separated protein assemblies, owing to their size, dynamics and heterogeneity. In this Perspective, we discuss recent advances in mass spectrometry (MS) that offer several promising approaches for the study of protein LLPS. We survey MS tools that have provided valuable insights into other insoluble protein systems, such as amyloids, and describe how they can also be applied to study proteins that undergo LLPS. On the basis of these recent advances, we propose to integrate MS into the experimental workflow for LLPS studies. We identify specific challenges and future opportunities for the analysis of protein condensate structure and function by MS.
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Affiliation(s)
- Cagla Sahin
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet-Biomedicum, Solna, Sweden.
- Structural Biology and NMR laboratory and the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
| | - Axel Leppert
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet-Biomedicum, Solna, Sweden
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet-Biomedicum, Solna, Sweden.
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
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24
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Schmid SY, Lachowski K, Chiang HT, Pozzo L, De Yoreo J, Zhang S. Mechanisms of Biomolecular Self-Assembly Investigated Through In Situ Observations of Structures and Dynamics. Angew Chem Int Ed Engl 2023; 62:e202309725. [PMID: 37702227 DOI: 10.1002/anie.202309725] [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: 07/09/2023] [Indexed: 09/14/2023]
Abstract
Biomolecular self-assembly of hierarchical materials is a precise and adaptable bottom-up approach to synthesizing across scales with considerable energy, health, environment, sustainability, and information technology applications. To achieve desired functions in biomaterials, it is essential to directly observe assembly dynamics and structural evolutions that reflect the underlying energy landscape and the assembly mechanism. This review will summarize the current understanding of biomolecular assembly mechanisms based on in situ characterization and discuss the broader significance and achievements of newly gained insights. In addition, we will also introduce how emerging deep learning/machine learning-based approaches, multiparametric characterization, and high-throughput methods can boost the development of biomolecular self-assembly. The objective of this review is to accelerate the development of in situ characterization approaches for biomolecular self-assembly and to inspire the next generation of biomimetic materials.
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Affiliation(s)
- Sakshi Yadav Schmid
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Kacper Lachowski
- Chemical Engineering, University of Washington, Seattle, WA 98105, USA
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98105, USA
| | - Huat Thart Chiang
- Chemical Engineering, University of Washington, Seattle, WA 98105, USA
| | - Lilo Pozzo
- Chemical Engineering, University of Washington, Seattle, WA 98105, USA
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98105, USA
- Materials Science and Engineering, University of Washington, Seattle, WA 98105, USA
| | - Jim De Yoreo
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
- Materials Science and Engineering, University of Washington, Seattle, WA 98105, USA
| | - Shuai Zhang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99354, USA
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98105, USA
- Materials Science and Engineering, University of Washington, Seattle, WA 98105, USA
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25
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Ripin N, Parker R. Formation, function, and pathology of RNP granules. Cell 2023; 186:4737-4756. [PMID: 37890457 PMCID: PMC10617657 DOI: 10.1016/j.cell.2023.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/28/2023] [Accepted: 09/07/2023] [Indexed: 10/29/2023]
Abstract
Ribonucleoprotein (RNP) granules are diverse membrane-less organelles that form through multivalent RNA-RNA, RNA-protein, and protein-protein interactions between RNPs. RNP granules are implicated in many aspects of RNA physiology, but in most cases their functions are poorly understood. RNP granules can be described through four key principles. First, RNP granules often arise because of the large size, high localized concentrations, and multivalent interactions of RNPs. Second, cells regulate RNP granule formation by multiple mechanisms including posttranslational modifications, protein chaperones, and RNA chaperones. Third, RNP granules impact cell physiology in multiple manners. Finally, dysregulation of RNP granules contributes to human diseases. Outstanding issues in the field remain, including determining the scale and molecular mechanisms of RNP granule function and how granule dysfunction contributes to human disease.
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Affiliation(s)
- Nina Ripin
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA.
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26
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Chowdhury A, Borgia A, Ghosh S, Sottini A, Mitra S, Eapen RS, Borgia MB, Yang T, Galvanetto N, Ivanović MT, Łukijańczuk P, Zhu R, Nettels D, Kundagrami A, Schuler B. Driving forces of the complex formation between highly charged disordered proteins. Proc Natl Acad Sci U S A 2023; 120:e2304036120. [PMID: 37796987 PMCID: PMC10576128 DOI: 10.1073/pnas.2304036120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 08/22/2023] [Indexed: 10/07/2023] Open
Abstract
Highly disordered complexes between oppositely charged intrinsically disordered proteins present a new paradigm of biomolecular interactions. Here, we investigate the driving forces of such interactions for the example of the highly positively charged linker histone H1 and its highly negatively charged chaperone, prothymosin α (ProTα). Temperature-dependent single-molecule Förster resonance energy transfer (FRET) experiments and isothermal titration calorimetry reveal ProTα-H1 binding to be enthalpically unfavorable, and salt-dependent affinity measurements suggest counterion release entropy to be an important thermodynamic driving force. Using single-molecule FRET, we also identify ternary complexes between ProTα and H1 in addition to the heterodimer at equilibrium and show how they contribute to the thermodynamics observed in ensemble experiments. Finally, we explain the observed thermodynamics quantitatively with a mean-field polyelectrolyte theory that treats counterion release explicitly. ProTα-H1 complex formation resembles the interactions between synthetic polyelectrolytes, and the underlying principles are likely to be of broad relevance for interactions between charged biomolecules in general.
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Affiliation(s)
- Aritra Chowdhury
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Alessandro Borgia
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Souradeep Ghosh
- Department of Physical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research Kolkata, Mohanpur741246, India
| | - Andrea Sottini
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Soumik Mitra
- Department of Physical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research Kolkata, Mohanpur741246, India
| | - Rohan S. Eapen
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | | | - Tianjin Yang
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Nicola Galvanetto
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
- Department of Physics, University of Zurich, Zurich8057, Switzerland
| | - Miloš T. Ivanović
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Paweł Łukijańczuk
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Ruijing Zhu
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
| | - Arindam Kundagrami
- Department of Physical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research Kolkata, Mohanpur741246, India
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Zurich8057, Switzerland
- Department of Physics, University of Zurich, Zurich8057, Switzerland
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27
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Poudyal M, Patel K, Gadhe L, Sawner AS, Kadu P, Datta D, Mukherjee S, Ray S, Navalkar A, Maiti S, Chatterjee D, Devi J, Bera R, Gahlot N, Joseph J, Padinhateeri R, Maji SK. Intermolecular interactions underlie protein/peptide phase separation irrespective of sequence and structure at crowded milieu. Nat Commun 2023; 14:6199. [PMID: 37794023 PMCID: PMC10550955 DOI: 10.1038/s41467-023-41864-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 09/21/2023] [Indexed: 10/06/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) has emerged as a crucial biological phenomenon underlying the sequestration of macromolecules (such as proteins and nucleic acids) into membraneless organelles in cells. Unstructured and intrinsically disordered domains are known to facilitate multivalent interactions driving protein LLPS. We hypothesized that LLPS could be an intrinsic property of proteins/polypeptides but with distinct phase regimes irrespective of their sequence and structure. To examine this, we studied many (a total of 23) proteins/polypeptides with different structures and sequences for LLPS study in the presence and absence of molecular crowder, polyethylene glycol (PEG-8000). We showed that all proteins and even highly charged polypeptides (under study) can undergo liquid condensate formation, however with different phase regimes and intermolecular interactions. We further demonstrated that electrostatic, hydrophobic, and H-bonding or a combination of such intermolecular interactions plays a crucial role in individual protein/peptide LLPS.
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Affiliation(s)
- Manisha Poudyal
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Komal Patel
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases, IIT Bombay, Powai, Mumbai, 400076, India
| | - Laxmikant Gadhe
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Ajay Singh Sawner
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Pradeep Kadu
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Debalina Datta
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Semanti Mukherjee
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Soumik Ray
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Ambuja Navalkar
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Siddhartha Maiti
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
- Department of Bioengineering, VIT Bhopal University, Bhopal-Indore Highway, Kothrikalan, Sehore, Madhya Pradesh, 466114, India
| | - Debdeep Chatterjee
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Jyoti Devi
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Riya Bera
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Nitisha Gahlot
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Jennifer Joseph
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India
| | - Samir K Maji
- Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, 400076, India.
- Sunita Sanghi Centre of Aging and Neurodegenerative Diseases, IIT Bombay, Powai, Mumbai, 400076, India.
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28
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Mekonnen G, Djaja N, Yuan X, Myong S. Advanced imaging techniques for studying protein phase separation in living cells and at single-molecule level. Curr Opin Chem Biol 2023; 76:102371. [PMID: 37523989 PMCID: PMC10528199 DOI: 10.1016/j.cbpa.2023.102371] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/04/2023] [Accepted: 06/24/2023] [Indexed: 08/02/2023]
Abstract
Protein-protein and protein-RNA interactions are essential for cell function and survival. These interactions facilitate the formation of ribonucleoprotein complexes and biomolecular condensates via phase separation. Such assembly is involved in transcription, splicing, translation and stress response. When dysregulated, proteins and RNA can undergo irreversible aggregation which can be cytotoxic and pathogenic. Despite technical advances in investigating biomolecular condensates, achieving the necessary spatiotemporal resolution to deduce the parameters that govern their assembly and behavior has been challenging. Many laboratories have applied advanced microscopy methods for imaging condensates. For example, single molecule imaging methods have enabled the detection of RNA-protein interaction, protein-protein interaction, protein conformational dynamics, and diffusional motion of molecules that report on the intrinsic molecular interactions underlying liquid-liquid phase separation. This review will outline advances in both microscopy and spectroscopy techniques which allow single molecule detection and imaging, and how these techniques can be used to probe unique aspects of biomolecular condensates.
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Affiliation(s)
- Gemechu Mekonnen
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Nathalie Djaja
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Xincheng Yuan
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Sua Myong
- Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA; Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA.
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29
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Namitz KEW, Showalter SA, Cosgrove MS. Phase separation promotes a highly active oligomeric scaffold of the MLL1 core complex for regulation of histone H3K4 methylation. J Biol Chem 2023; 299:105204. [PMID: 37660926 PMCID: PMC10551905 DOI: 10.1016/j.jbc.2023.105204] [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: 07/05/2023] [Revised: 08/18/2023] [Accepted: 08/24/2023] [Indexed: 09/05/2023] Open
Abstract
Enzymes that regulate the degree of histone H3 lysine 4 (H3K4) methylation are crucial for proper cellular differentiation and are frequently mutated in cancer. The Mixed lineage leukemia (MLL) family of enzymes deposit H3K4 mono-, di-, or trimethylation at distinct genomic locations, requiring precise spatial and temporal control. Despite evidence that the degree of H3K4 methylation is controlled in part by a hierarchical assembly pathway with key subcomplex components, we previously found that the assembled state of the MLL1 core complex is not favored at physiological temperature. To better understand this paradox, we tested the hypothesis that increasing the concentration of subunits in a biomolecular condensate overcomes this thermodynamic barrier via mass action. Here, we demonstrate that MLL1 core complex phase separation stimulates enzymatic activity up to 60-fold but not primarily by concentrating subunits into droplets. Instead, we found that stimulated activity is largely due to the formation of an altered oligomeric scaffold that greatly reduces substrate Km. We posit that phase separation-induced scaffolding of the MLL1 core complex is a potential "switch-like" mechanism for spatiotemporal control of H3K4 methylation through the rapid formation or dissolution of biomolecular condensates within RNA Pol II transcription factories.
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Affiliation(s)
- Kevin E W Namitz
- Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA
| | - Scott A Showalter
- Department of Chemistry, Penn State University, University Park, Pennsylvania, USA
| | - Michael S Cosgrove
- Department of Biochemistry and Molecular Biology, State University of New York (SUNY) Upstate Medical University, Syracuse, New York, USA.
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30
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Ray S, Mason TO, Boyens-Thiele L, Farzadfard A, Larsen JA, Norrild RK, Jahnke N, Buell AK. Mass photometric detection and quantification of nanoscale α-synuclein phase separation. Nat Chem 2023; 15:1306-1316. [PMID: 37337111 DOI: 10.1038/s41557-023-01244-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 05/19/2023] [Indexed: 06/21/2023]
Abstract
Protein liquid-liquid phase separation can lead to disease-related amyloid fibril formation. The mechanisms of conversion of monomeric protein into condensate droplets and of the latter into fibrils remain elusive. Here, using mass photometry, we demonstrate that the Parkinson's disease-related protein, α-synuclein, can form dynamic nanoscale clusters at physiologically relevant, sub-saturated concentrations. Nanoclusters nucleate in bulk solution and promote amyloid fibril formation of the dilute-phase monomers upon ageing. Their formation is instantaneous, even under conditions where macroscopic assemblies appear only after several days. The slow growth of the nanoclusters can be attributed to a kinetic barrier, probably due to an interfacial penalty from the charged C terminus of α-synuclein. Our findings reveal that α-synuclein phase separation occurs at much wider ranges of solution conditions than reported so far. Importantly, we establish mass photometry as a promising methodology to detect and quantify nanoscale precursors of phase separation. We also demonstrate its general applicability by probing the existence of nanoclusters of a non-amyloidogenic protein, Ddx4n1.
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Affiliation(s)
- Soumik Ray
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Thomas O Mason
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Lars Boyens-Thiele
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Azad Farzadfard
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Jacob Aunstrup Larsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Rasmus K Norrild
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Nadin Jahnke
- Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Alexander K Buell
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark.
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31
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Alston JJ, Soranno A. Condensation Goes Viral: A Polymer Physics Perspective. J Mol Biol 2023; 435:167988. [PMID: 36709795 PMCID: PMC10368797 DOI: 10.1016/j.jmb.2023.167988] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/18/2023] [Accepted: 01/21/2023] [Indexed: 01/27/2023]
Abstract
The past decade has seen a revolution in our understanding of how the cellular environment is organized, where an incredible body of work has provided new insights into the role played by membraneless organelles. These rapid advancements have been made possible by an increasing awareness of the peculiar physical properties that give rise to such bodies and the complex biology that enables their function. Viral infections are not extraneous to this. Indeed, in host cells, viruses can harness existing membraneless compartments or, even, induce the formation of new ones. By hijacking the cellular machinery, these intracellular bodies can assist in the replication, assembly, and packaging of the viral genome as well as in the escape of the cellular immune response. Here, we provide a perspective on the fundamental polymer physics concepts that may help connect and interpret the different observed phenomena, ranging from the condensation of viral genomes to the phase separation of multicomponent solutions. We complement the discussion of the physical basis with a description of biophysical methods that can provide quantitative insights for testing and developing theoretical and computational models.
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Affiliation(s)
- Jhullian J Alston
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA; Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 St Euclid Ave, 63110 Saint Louis, MO, USA; Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130 Saint Louis, MO, USA.
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32
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Toledo PL, Gianotti AR, Vazquez DS, Ermácora MR. Protein nanocondensates: the next frontier. Biophys Rev 2023; 15:515-530. [PMID: 37681092 PMCID: PMC10480383 DOI: 10.1007/s12551-023-01105-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 07/21/2023] [Indexed: 09/09/2023] Open
Abstract
Over the past decade, myriads of studies have highlighted the central role of protein condensation in subcellular compartmentalization and spatiotemporal organization of biological processes. Conceptually, protein condensation stands at the highest level in protein structure hierarchy, accounting for the assembly of bodies ranging from thousands to billions of molecules and for densities ranging from dense liquids to solid materials. In size, protein condensates range from nanocondensates of hundreds of nanometers (mesoscopic clusters) to phase-separated micron-sized condensates. In this review, we focus on protein nanocondensation, a process that can occur in subsaturated solutions and can nucleate dense liquid phases, crystals, amorphous aggregates, and fibers. We discuss the nanocondensation of proteins in the light of general physical principles and examine the biophysical properties of several outstanding examples of nanocondensation. We conclude that protein nanocondensation cannot be fully explained by the conceptual framework of micron-scale biomolecular condensation. The evolution of nanocondensates through changes in density and order is currently under intense investigation, and this should lead to the development of a general theoretical framework, capable of encompassing the full range of sizes and densities found in protein condensates.
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Affiliation(s)
- Pamela L. Toledo
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Alejo R. Gianotti
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Diego S. Vazquez
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Mario R. Ermácora
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, 1876, Bernal, Buenos Aires, Argentina
- Grupo de Biología Estructural y Biotecnología, IMBICE, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
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33
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Szała-Mendyk B, Phan TM, Mohanty P, Mittal J. Challenges in studying the liquid-to-solid phase transitions of proteins using computer simulations. Curr Opin Chem Biol 2023; 75:102333. [PMID: 37267850 PMCID: PMC10527940 DOI: 10.1016/j.cbpa.2023.102333] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/24/2023] [Accepted: 04/30/2023] [Indexed: 06/04/2023]
Abstract
"Membraneless organelles," also referred to as biomolecular condensates, perform a variety of cellular functions and their dysregulation is implicated in cancer and neurodegeneration. In the last two decades, liquid-liquid phase separation (LLPS) of intrinsically disordered and multidomain proteins has emerged as a plausible mechanism underlying the formation of various biomolecular condensates. Further, the occurrence of liquid-to-solid transitions within liquid-like condensates may give rise to amyloid structures, implying a biophysical link between phase separation and protein aggregation. Despite significant advances, uncovering the microscopic details of liquid-to-solid phase transitions using experiments remains a considerable challenge and presents an exciting opportunity for the development of computational models which provide valuable, complementary insights into the underlying phenomenon. In this review, we first highlight recent biophysical studies which provide new insights into the molecular mechanisms underlying liquid-to-solid (fibril) phase transitions of folded, disordered and multi-domain proteins. Next, we summarize the range of computational models used to study protein aggregation and phase separation. Finally, we discuss recent computational approaches which attempt to capture the underlying physics of liquid-to-solid transitions along with their merits and shortcomings.
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Affiliation(s)
- Beata Szała-Mendyk
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, TAMU 3127, College Station, 77843, Texas, United States.
| | - Tien Minh Phan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, TAMU 3127, College Station, 77843, Texas, United States.
| | - Priyesh Mohanty
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, TAMU 3127, College Station, 77843, Texas, United States.
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, TAMU 3127, College Station, 77843, Texas, United States; Department of Chemistry, Texas A&M University, TAMU 3255, College Station, 77843, Texas, United States; Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, TAMU 3255, College Station, 77843, Texas, United States.
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34
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Sárkány Z, Rocha F, Bratek‐Skicki A, Tompa P, Macedo‐Ribeiro S, Martins PM. Quantification of Surface Tension Effects and Nucleation-and-Growth Rates during Self-Assembly of Biological Condensates. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301501. [PMID: 37279376 PMCID: PMC10427409 DOI: 10.1002/advs.202301501] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/12/2023] [Indexed: 06/08/2023]
Abstract
Liquid-solid and liquid-liquid phase separation (PS) drives the formation of functional and disease-associated biological assemblies. Principles of phase equilibrium are here employed to derive a general kinetic solution that predicts the evolution of the mass and size of biological assemblies. Thermodynamically, protein PS is determined by two measurable concentration limits: the saturation concentration and the critical solubility. Due to surface tension effects, the critical solubility can be higher than the saturation concentration for small, curved nuclei. Kinetically, PS is characterized by the primary nucleation rate constant and a combined rate constant accounting for growth and secondary nucleation. It is demonstrated that the formation of a limited number of large condensates is possible without active mechanisms of size control and in the absence of coalescence phenomena. The exact analytical solution can be used to interrogate how the elementary steps of PS are affected by candidate drugs.
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Affiliation(s)
- Zsuzsa Sárkány
- IBMC − Instituto de Biologia Molecular e CelularUniversidade do PortoPorto4150–180Portugal
- i3S − Instituto de Investigação e Inovação em SaúdeUniversidade do PortoPorto4150–180Portugal
| | - Fernando Rocha
- LEPABE − Laboratory for Process Engineering Environment Biotechnology and EnergyFaculdade de Engenharia da Universidade do PortoPorto4200‐465Portugal
| | - Anna Bratek‐Skicki
- Jerzy Haber Institute of Catalysis and Surface ChemistryPolish Academy of SciencesNiezapominajek 8KrakowPL30239Poland
- VIB‐VUB Center for Structural BiologyVlaams Instituut voor BiotechnologyBrussels1050 IxellesBelgium
- Structural Biology Brussels (SBB)Bioengineering Sciences DepartmentVrije Universiteit Brussel (VUB)BrusselsB‐1050Belgium
| | - Peter Tompa
- VIB‐VUB Center for Structural BiologyVlaams Instituut voor BiotechnologyBrussels1050 IxellesBelgium
- Structural Biology Brussels (SBB)Bioengineering Sciences DepartmentVrije Universiteit Brussel (VUB)BrusselsB‐1050Belgium
- Institute of EnzymologyResearch Centre for Natural SciencesBudapest1117Hungary
| | - Sandra Macedo‐Ribeiro
- IBMC − Instituto de Biologia Molecular e CelularUniversidade do PortoPorto4150–180Portugal
- i3S − Instituto de Investigação e Inovação em SaúdeUniversidade do PortoPorto4150–180Portugal
| | - Pedro M. Martins
- IBMC − Instituto de Biologia Molecular e CelularUniversidade do PortoPorto4150–180Portugal
- i3S − Instituto de Investigação e Inovação em SaúdeUniversidade do PortoPorto4150–180Portugal
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35
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Abstract
Biomolecular condensates are reversible compartments that form through a process called phase separation. Post-translational modifications like ADP-ribosylation can nucleate the formation of these condensates by accelerating the self-association of proteins. Poly(ADP-ribose) (PAR) chains are remarkably transient modifications with turnover rates on the order of minutes, yet they can be required for the formation of granules in response to oxidative stress, DNA damage, and other stimuli. Moreover, accumulation of PAR is linked with adverse phase transitions in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In this review, we provide a primer on how PAR is synthesized and regulated, the diverse structures and chemistries of ADP-ribosylation modifications, and protein-PAR interactions. We review substantial progress in recent efforts to determine the molecular mechanism of PAR-mediated phase separation, and we further delineate how inhibitors of PAR polymerases may be effective treatments for neurodegenerative pathologies. Finally, we highlight the need for rigorous biochemical interrogation of ADP-ribosylation in vivo and in vitro to clarify the exact pathway from PARylation to condensate formation.
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Affiliation(s)
- Kevin Rhine
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hana M Odeh
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - James Shorter
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - Sua Myong
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
- Physics Frontier Center (Center for the Physics of Living Cells), University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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36
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Abstract
Multivalent proteins and nucleic acids, collectively referred to as multivalent associative biomacromolecules, provide the driving forces for the formation and compositional regulation of biomolecular condensates. Here, we review the key concepts of phase transitions of aqueous solutions of associative biomacromolecules, specifically proteins that include folded domains and intrinsically disordered regions. The phase transitions of these systems come under the rubric of coupled associative and segregative transitions. The concepts underlying these processes are presented, and their relevance to biomolecular condensates is discussed.
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Affiliation(s)
- Rohit V Pappu
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Samuel R Cohen
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, Missouri 63130, United States
- Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Furqan Dar
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Mina Farag
- Department of Biomedical Engineering, Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Mrityunjoy Kar
- Max Planck Institute of Cell Biology and Genetics, 01307 Dresden, Germany
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37
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Hutin S, Kumita JR, Strotmann VI, Dolata A, Ling WL, Louafi N, Popov A, Milhiet PE, Blackledge M, Nanao MH, Wigge PA, Stahl Y, Costa L, Tully MD, Zubieta C. Phase separation and molecular ordering of the prion-like domain of the Arabidopsis thermosensory protein EARLY FLOWERING 3. Proc Natl Acad Sci U S A 2023; 120:e2304714120. [PMID: 37399408 PMCID: PMC10334799 DOI: 10.1073/pnas.2304714120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/06/2023] [Indexed: 07/05/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) is an important mechanism enabling the dynamic compartmentalization of macromolecules, including complex polymers such as proteins and nucleic acids, and occurs as a function of the physicochemical environment. In the model plant, Arabidopsis thaliana, LLPS by the protein EARLY FLOWERING3 (ELF3) occurs in a temperature-sensitive manner and controls thermoresponsive growth. ELF3 contains a largely unstructured prion-like domain (PrLD) that acts as a driver of LLPS in vivo and in vitro. The PrLD contains a poly-glutamine (polyQ) tract, whose length varies across natural Arabidopsis accessions. Here, we use a combination of biochemical, biophysical, and structural techniques to investigate the dilute and condensed phases of the ELF3 PrLD with varying polyQ lengths. We demonstrate that the dilute phase of the ELF3 PrLD forms a monodisperse higher-order oligomer that does not depend on the presence of the polyQ sequence. This species undergoes LLPS in a pH- and temperature-sensitive manner and the polyQ region of the protein tunes the initial stages of phase separation. The liquid phase rapidly undergoes aging and forms a hydrogel as shown by fluorescence and atomic force microscopies. Furthermore, we demonstrate that the hydrogel assumes a semiordered structure as determined by small-angle X-ray scattering, electron microscopy, and X-ray diffraction. These experiments demonstrate a rich structural landscape for a PrLD protein and provide a framework to describe the structural and biophysical properties of biomolecular condensates.
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Affiliation(s)
- Stephanie Hutin
- Laboratoire de Physiologie Cellulaire et Végétale, University Grenoble Alpes, Centre national de la recherche scientifique, Commissariat à l'énergie atomique et aux énergies alternatives, Institut national de recherche pour l’agriculture, l’alimentation et l’environnement, Institut de recherche interdisciplinaire de Grenoble, Grenoble38054, France
| | - Janet R. Kumita
- Department of Pharmacology, University of Cambridge, CambridgeCB2 1PD, United Kingdom
| | - Vivien I. Strotmann
- Institute for Developmental Genetics, Heinrich-Heine University, DüsseldorfD-40225, Germany
| | - Anika Dolata
- Institute for Developmental Genetics, Heinrich-Heine University, DüsseldorfD-40225, Germany
| | - Wai Li Ling
- University Grenoble Alpes, Commissariat à l'énergie atomique et aux énergies alternatives, Centre national de la recherche scientifique, Institut de Biologie Structurale, Institut de recherche interdisciplinaire de Grenoble, Grenoble38000, France
| | - Nessim Louafi
- Centre de Biologie Structurale, University Montpellier, Centre national de la recherche scientifique, Institut national de la santé et de la recherche médicale, Montpellier34090, France
| | - Anton Popov
- European Synchrotron Radiation Facility, Structural Biology Group, Grenoble38000, France
| | - Pierre-Emmanuel Milhiet
- Centre de Biologie Structurale, University Montpellier, Centre national de la recherche scientifique, Institut national de la santé et de la recherche médicale, Montpellier34090, France
| | - Martin Blackledge
- University Grenoble Alpes, Commissariat à l'énergie atomique et aux énergies alternatives, Centre national de la recherche scientifique, Institut de Biologie Structurale, Institut de recherche interdisciplinaire de Grenoble, Grenoble38000, France
| | - Max H. Nanao
- European Synchrotron Radiation Facility, Structural Biology Group, Grenoble38000, France
| | - Philip A. Wigge
- Leibniz-Institut für Gemüse- und Zierpflanzenbau, 14979Grossbeeren, Germany
- Institute of Biochemistry and Biology, University of Potsdam, 14476Potsdam, Germany
| | - Yvonne Stahl
- Institute for Developmental Genetics, Heinrich-Heine University, DüsseldorfD-40225, Germany
- Cluster of Excellence on Plant Sciences, Heinrich-Heine University, DüsseldorfD-40225, Germany
| | - Luca Costa
- Centre de Biologie Structurale, University Montpellier, Centre national de la recherche scientifique, Institut national de la santé et de la recherche médicale, Montpellier34090, France
| | - Mark D. Tully
- European Synchrotron Radiation Facility, Structural Biology Group, Grenoble38000, France
| | - Chloe Zubieta
- Laboratoire de Physiologie Cellulaire et Végétale, University Grenoble Alpes, Centre national de la recherche scientifique, Commissariat à l'énergie atomique et aux énergies alternatives, Institut national de recherche pour l’agriculture, l’alimentation et l’environnement, Institut de recherche interdisciplinaire de Grenoble, Grenoble38054, France
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38
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Ziethen N, Kirschbaum J, Zwicker D. Nucleation of Chemically Active Droplets. PHYSICAL REVIEW LETTERS 2023; 130:248201. [PMID: 37390433 DOI: 10.1103/physrevlett.130.248201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 05/10/2023] [Indexed: 07/02/2023]
Abstract
Driven chemical reactions can control the macroscopic properties of droplets, like their size. Such active droplets are critical in structuring the interior of biological cells. Cells also need to control where and when droplets appear, so they need to control droplet nucleation. Our numerical simulations demonstrate that reactions generally suppress nucleation if they stabilize the homogeneous state. An equilibrium surrogate model reveals that reactions increase the effective energy barrier of nucleation, enabling quantitative predictions of the increased nucleation times. Moreover, the surrogate model allows us to construct a phase diagram, which summarizes how reactions affect the stability of the homogeneous phase and the droplet state. This simple picture provides accurate predictions of how driven reactions delay nucleation, which is relevant for understanding droplets in biological cells and chemical engineering.
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Affiliation(s)
- Noah Ziethen
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17 37077, Göttingen, Germany
| | - Jan Kirschbaum
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17 37077, Göttingen, Germany
| | - David Zwicker
- Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17 37077, Göttingen, Germany
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39
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Jeon J, Yau WM, Tycko R. Early events in amyloid-β self-assembly probed by time-resolved solid state NMR and light scattering. Nat Commun 2023; 14:2964. [PMID: 37221174 DOI: 10.1038/s41467-023-38494-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/04/2023] [Indexed: 05/25/2023] Open
Abstract
Self-assembly of amyloid-β peptides leads to oligomers, protofibrils, and fibrils that are likely instigators of neurodegeneration in Alzheimer's disease. We report results of time-resolved solid state nuclear magnetic resonance (ssNMR) and light scattering experiments on 40-residue amyloid-β (Aβ40) that provide structural information for oligomers that form on time scales from 0.7 ms to 1.0 h after initiation of self-assembly by a rapid pH drop. Low-temperature ssNMR spectra of freeze-trapped intermediates indicate that β-strand conformations within and contacts between the two main hydrophobic segments of Aβ40 develop within 1 ms, while light scattering data imply a primarily monomeric state up to 5 ms. Intermolecular contacts involving residues 18 and 33 develop within 0.5 s, at which time Aβ40 is approximately octameric. These contacts argue against β-sheet organizations resembling those found previously in protofibrils and fibrils. Only minor changes in the Aβ40 conformational distribution are detected as larger assemblies develop.
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Affiliation(s)
- Jaekyun Jeon
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
- Institute for Bioscience and Biotechnology Research, University of Maryland/National Institute of Standards and Technology, Rockville, MD, 20850, USA
| | - Wai-Ming Yau
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA.
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40
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Bertrand E, Demongin C, Dobra I, Rengifo-Gonzalez JC, Singatulina AS, Sukhanova MV, Lavrik OI, Pastré D, Hamon L. FUS fibrillation occurs through a nucleation-based process below the critical concentration required for liquid-liquid phase separation. Sci Rep 2023; 13:7772. [PMID: 37179431 PMCID: PMC10183042 DOI: 10.1038/s41598-023-34558-1] [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: 09/06/2022] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
FUS is an RNA-binding protein involved in familiar forms of ALS and FTLD that also assembles into fibrillar cytoplasmic aggregates in some neurodegenerative diseases without genetic causes. The self-adhesive prion-like domain in FUS generates reversible condensates via the liquid-liquid phase separation process (LLPS) whose maturation can lead to the formation of insoluble fibrillar aggregates in vitro, consistent with the appearance of cytoplasmic inclusions in ageing neurons. Using a single-molecule imaging approach, we reveal that FUS can assemble into nanofibrils at concentrations in the nanomolar range. These results suggest that the formation of fibrillar aggregates of FUS could occur in the cytoplasm at low concentrations of FUS, below the critical ones required to trigger the liquid-like condensate formation. Such nanofibrils may serve as seeds for the formation of pathological inclusions. Interestingly, the fibrillation of FUS at low concentrations is inhibited by its binding to mRNA or after the phosphorylation of its prion-like domain, in agreement with previous models.
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Affiliation(s)
- Emilie Bertrand
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, 91025, Evry, France
| | - Clément Demongin
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, 91025, Evry, France
| | - Ioana Dobra
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, 91025, Evry, France
| | | | - Anastasia S Singatulina
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, 91025, Evry, France
- Institute of Chemical Biology and Fundamental Medicine, Novosibirsk, Russia, 630090
| | - Maria V Sukhanova
- Institute of Chemical Biology and Fundamental Medicine, Novosibirsk, Russia, 630090
| | - Olga I Lavrik
- Institute of Chemical Biology and Fundamental Medicine, Novosibirsk, Russia, 630090
| | - David Pastré
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, 91025, Evry, France
| | - Loic Hamon
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, 91025, Evry, France.
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41
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Yoo YJ, Cho G, Kim D, Kim Y, Yun N, Oh YJ. Asymmetric dimethylation of AMPKα1 by PRMT6 contributes to the formation of phase-separated puncta. Biochem Biophys Res Commun 2023; 666:92-100. [PMID: 37178510 DOI: 10.1016/j.bbrc.2023.04.089] [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: 03/20/2023] [Revised: 04/14/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023]
Abstract
AMP-activated protein kinase (AMPK) is a heterotrimeric serine/threonine kinase comprising α, β, and γ subunits. AMPK is involved in intracellular energy metabolism and functions as a switch that turns various biological pathways in eukaryotes on and off. Several post-translational modifications regulating AMPK function have been demonstrated, including phosphorylation, acetylation, and ubiquitination; however, arginine methylation has not been reported in AMPKα1. We investigated whether arginine methylation occurs in AMPKα1. Screening experiments revealed arginine methylation of AMPKα1 mediated by protein arginine methyltransferase 6 (PRMT6). In vitro methylation and co-immunoprecipitation assays indicated that PRMT6 can directly interact with and methylate AMPKα1 without involvement of other intracellular components. In vitro methylation assays with truncated and point mutants of AMPKα1 revealed that Arg403 is the residue methylated by PRMT6. Immunocytochemical studies showed that the number of AMPKα1 puncta was enhanced in saponin-permeabilized cells when AMPKα1 was co-expressed with PRMT6, suggesting that PRMT6-mediated methylation of AMPKα1 at Arg403 alters the physiological characteristics of AMPKα1 and may lead to liquid-liquid phase separation.
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Affiliation(s)
- Yeon Ju Yoo
- Department of Systems Biology Yonsei University College of Life Science and Biotechnology, Seoul, 03722, South Korea
| | - Giseong Cho
- Department of Systems Biology Yonsei University College of Life Science and Biotechnology, Seoul, 03722, South Korea
| | - Dana Kim
- Department of Systems Biology Yonsei University College of Life Science and Biotechnology, Seoul, 03722, South Korea
| | - Yoonkyung Kim
- Department of Systems Biology Yonsei University College of Life Science and Biotechnology, Seoul, 03722, South Korea
| | - Nuri Yun
- Department of Systems Biology Yonsei University College of Life Science and Biotechnology, Seoul, 03722, South Korea; GNTPharma Science and Technology Center for Health, Incheon, 21983, South Korea.
| | - Young J Oh
- Department of Systems Biology Yonsei University College of Life Science and Biotechnology, Seoul, 03722, South Korea; GNTPharma Science and Technology Center for Health, Incheon, 21983, South Korea.
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42
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Zhang J, Huang Y, Bai F. Stochastic Monte Carlo Model for Simulating the Dynamic Liquid-Liquid Phase Separation in Bacterial Cells. J Phys Chem B 2023; 127:4145-4153. [PMID: 37130439 DOI: 10.1021/acs.jpcb.3c01696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
There is growing evidence showing that many critical biological processes are driven by biomolecule condensates through liquid-liquid phase separation (LLPS). Although the qualitative observation and description of LLPS have been well documented, quantitative simulations of the time-dependent progression of LLPS in live cells are generally lacking. In this work, we build a stochastic Monte Carlo model to simulate the dynamic LLPS process during the formation of bacterial aggresomes. We demonstrate that the size distribution of the protein condensates evolves from an exponential-like to a bimodal-like pattern, and the number of condensates increases at the beginning and then decreases after reaching a maximum. Incorporating diffusion and collision, our simplified model recapitulates the two-step LLPS process in which many smaller condensates are formed in the first step and then merged into a few larger ones. We further reveal that the condensation speed, which can be defined by the condensates formed in unit time during the first step, is mainly determined by both the collision energy barrier and the initial protein density, while the number of condensates at the equilibrium is mainly associated with the dissociation energy barrier. Moreover, the LLPS process is not sensitive to temperature changes ranging around physiological conditions. Additionally, we consider the effect of the nucleation energy barrier on LLPS. We find that a higher nucleation energy barrier brings a slower condensation speed. Overall, we simulate the spatiotemporal dynamics of the LLPS process and provide qualitative guidance for understanding the dynamics of LLPS in bacterial cells, which can faithfully recapitulate experimental observations and facilitate the design of future experimental tests.
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Affiliation(s)
- Jingpeng Zhang
- Biomedical Pioneering Innovation Center, Peking University, Beijing 100871, China
- School of Life Sciences, Peking University, Beijing 100871, China
| | - Yanyi Huang
- Biomedical Pioneering Innovation Center, Peking University, Beijing 100871, China
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Institute for Cell Analysis, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Fan Bai
- Biomedical Pioneering Innovation Center, Peking University, Beijing 100871, China
- School of Life Sciences, Peking University, Beijing 100871, China
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43
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Zielinski KA, Katz AM, Calvey GD, Pabit SA, Milano SK, Aplin C, San Emeterio J, Cerione RA, Pollack L. Chaotic advection mixer for capturing transient states of diverse biological macromolecular systems with time-resolved small-angle X-ray scattering. IUCRJ 2023; 10:363-375. [PMID: 37144817 PMCID: PMC10161774 DOI: 10.1107/s2052252523003482] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/17/2023] [Indexed: 05/06/2023]
Abstract
Advances in time-resolved structural techniques, mainly in macromolecular crystallography and small-angle X-ray scattering (SAXS), allow for a detailed view of the dynamics of biological macromolecules and reactions between binding partners. Of particular promise, are mix-and-inject techniques, which offer a wide range of experimental possibility as microfluidic mixers are used to rapidly combine two species just prior to data collection. Most mix-and-inject approaches rely on diffusive mixers, which have been effectively used within crystallography and SAXS for a variety of systems, but their success is dependent on a specific set of conditions to facilitate fast diffusion for mixing. The use of a new chaotic advection mixer designed for microfluidic applications helps to further broaden the types of systems compatible with time-resolved mixing experiments. The chaotic advection mixer can create ultra-thin, alternating layers of liquid, enabling faster diffusion so that even more slowly diffusing molecules, like proteins or nucleic acids, can achieve fast mixing on timescales relevant to biological reactions. This mixer was first used in UV-vis absorbance and SAXS experiments with systems of a variety of molecular weights, and thus diffusion speeds. Careful effort was also dedicated to making a loop-loading sample-delivery system that consumes as little sample as possible, enabling the study of precious, laboratory-purified samples. The combination of the versatile mixer with low sample consumption opens the door to many new applications for mix-and-inject studies.
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Affiliation(s)
- Kara A. Zielinski
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York USA
| | - Andrea M. Katz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York USA
| | - George D. Calvey
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York USA
| | - Suzette A. Pabit
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York USA
| | - Shawn K. Milano
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York USA
| | - Cody Aplin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York USA
| | - Josue San Emeterio
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York USA
| | - Richard A. Cerione
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York USA
- Department of Molecular Medicine, Cornell University, Ithaca, New York USA
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York USA
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44
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Pan J, Zhang W, Zhu J, Tan J, Huang Y, Mo K, Tong Y, Xie Z, Ke Y, Zheng H, Ouyang H, Shi X, Gao L. Arrested Phase Separation Enables High-Performance Keratoprostheses. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2207750. [PMID: 36680510 DOI: 10.1002/adma.202207750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 12/24/2022] [Indexed: 06/17/2023]
Abstract
Corneal transplantation is impeded by donor shortages, immune rejection, and ethical reservations. Pre-made cornea prostheses (keratoprostheses) offer a proven option to alleviate these issues. Ideal keratoprostheses must possess optical clarity and mechanical robustness, but also high permeability, processability, and recyclability. Here, it is shown that rationally controlling the extent of arrested phase separation can lead to optimized multiscale structure that reconciles permeability and transparency, a previously conflicting goal by common pore-forming strategies. The process is simply accomplished by hydrothermally treating a dense and transparent hydrophobic association hydrogel. The examination of multiscale structure evolution during hydrothermal treatment reveals that the phase separation with upper miscibility gap evolves to confer time-dependent pore growth due to slow dynamics of polymer-rich phase which is close to vitrification. Such a process can render a combination of multiple desired properties that equal or surpass those of the state-of-the-art keratoprostheses. In vivo tests confirm that the keratoprosthesis can effectively repair corneal perforation and restore a transparent cornea with treatment outcomes akin to that of allo-keratoplasty. The keratoprosthesis is easy to access and convenient to carry, and thus would be an effective temporary substitute for a corneal allograft in emergency conditions.
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Affiliation(s)
- Jiageng Pan
- School of Chemical Engineering and Light Industry, Gangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Wang Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, P. R. China
| | - Jin Zhu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, P. R. China
| | - Jieying Tan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, P. R. China
| | - Ying Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, P. R. China
| | - Kunlun Mo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, P. R. China
| | - Yan Tong
- School of Materials, Sun Yat-sen University, Guangzhou, 510060, P. R. China
| | - Zhenhua Xie
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P. R. China
- Spallation Neutron Source Science Center, Dongguan, 523803, P. R. China
| | - Yubin Ke
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P. R. China
- Spallation Neutron Source Science Center, Dongguan, 523803, P. R. China
| | - Huade Zheng
- School of Materials Science and Engineering, South China University of Technology, Guanghzhou, 510640, P. R. China
| | - Hong Ouyang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, P. R. China
| | - Xuetao Shi
- School of Materials Science and Engineering, South China University of Technology, Guanghzhou, 510640, P. R. China
| | - Liang Gao
- School of Chemical Engineering and Light Industry, Gangdong University of Technology, Guangzhou, 510006, P. R. China
- Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory (Rongjiang Laboratory), Jieyang, 515200, P. R. China
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45
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Li L, Paloni M, Finney AR, Barducci A, Salvalaglio M. Nucleation of Biomolecular Condensates from Finite-Sized Simulations. J Phys Chem Lett 2023; 14:1748-1755. [PMID: 36758221 PMCID: PMC9940850 DOI: 10.1021/acs.jpclett.2c03512] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
The nucleation of protein condensates is a concentration-driven process of assembly. When modeled in the canonical ensemble, condensation is affected by finite-size effects. Here, we present a general and efficient route for obtaining ensemble properties of protein condensates in the macroscopic limit from finite-sized nucleation simulations. The approach is based on a theoretical description of droplet nucleation in the canonical ensemble and enables estimation of thermodynamic and kinetic parameters, such as the macroscopic equilibrium density of the dilute protein phase, the surface tension of the condensates, and nucleation free energy barriers. We apply the method to coarse-grained simulations of NDDX4 and FUS-LC, two phase-separating disordered proteins with different physicochemical characteristics. Our results show that NDDX4 condensate droplets, characterized by lower surface tension, higher solubility, and faster monomer exchange dynamics compared to those of FUS-LC, form with negligible nucleation barriers. In contrast, FUS-LC condensates form via an activated process over a wide range of concentrations.
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Affiliation(s)
- Lunna Li
- Thomas
Young Centre and Department of Chemical Engineering, University College London, London WC1E 7JE, U.K.
| | - Matteo Paloni
- Université
de Montpellier, Centre de Biologie Structurale
(CBS), CNRS, INSERM, 34090 Montpellier, France
| | - Aaron R. Finney
- Thomas
Young Centre and Department of Chemical Engineering, University College London, London WC1E 7JE, U.K.
| | - Alessandro Barducci
- Université
de Montpellier, Centre de Biologie Structurale
(CBS), CNRS, INSERM, 34090 Montpellier, France
| | - Matteo Salvalaglio
- Thomas
Young Centre and Department of Chemical Engineering, University College London, London WC1E 7JE, U.K.
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46
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Byer AS, Pei X, Patterson MG, Ando N. Small-angle X-ray scattering studies of enzymes. Curr Opin Chem Biol 2023; 72:102232. [PMID: 36462455 PMCID: PMC9992928 DOI: 10.1016/j.cbpa.2022.102232] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/14/2022] [Accepted: 10/22/2022] [Indexed: 12/02/2022]
Abstract
Enzyme function requires conformational changes to achieve substrate binding, domain rearrangements, and interactions with partner proteins, but these movements are difficult to observe. Small-angle X-ray scattering (SAXS) is a versatile structural technique that can probe such conformational changes under solution conditions that are physiologically relevant. Although it is generally considered a low-resolution structural technique, when used to study conformational changes as a function of time, ligand binding, or protein interactions, SAXS can provide rich insight into enzyme behavior, including subtle domain movements. In this perspective, we highlight recent uses of SAXS to probe structural enzyme changes upon ligand and partner-protein binding and discuss tools for signal deconvolution of complex protein solutions.
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Affiliation(s)
- Amanda S Byer
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Xiaokun Pei
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Michael G Patterson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Nozomi Ando
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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47
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Tesei G, Lindorff-Larsen K. Improved predictions of phase behaviour of intrinsically disordered proteins by tuning the interaction range. OPEN RESEARCH EUROPE 2023; 2:94. [PMID: 37645312 PMCID: PMC10450847 DOI: 10.12688/openreseurope.14967.2] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/16/2022] [Indexed: 08/31/2023]
Abstract
The formation and viscoelastic properties of condensates of intrinsically disordered proteins (IDPs) is dictated by amino acid sequence and solution conditions. Because of the involvement of biomolecular condensates in cell physiology and disease, advancing our understanding of the relationship between protein sequence and phase separation (PS) may have important implications in the formulation of new therapeutic hypotheses. Here, we present CALVADOS 2, a coarse-grained model of IDPs that accurately predicts conformational properties and propensities to undergo PS for diverse sequences and solution conditions. In particular, we systematically study the effect of varying the range of the nonionic interactions and use our findings to improve the temperature scale of the model. We further optimize the residue-specific model parameters against experimental data on the conformational properties of 55 proteins, while also leveraging 70 hydrophobicity scales from the literature to avoid overfitting the training data. Extensive testing shows that the model accurately predicts chain compaction and PS propensity for sequences of diverse length and charge patterning, as well as at different temperatures and salt concentrations.
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Affiliation(s)
- Giulio Tesei
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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48
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Tesei G, Lindorff-Larsen K. Improved predictions of phase behaviour of intrinsically disordered proteins by tuning the interaction range. OPEN RESEARCH EUROPE 2023; 2:94. [PMID: 37645312 PMCID: PMC10450847 DOI: 10.12688/openreseurope.14967.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/16/2022] [Indexed: 02/13/2024]
Abstract
The formation and viscoelastic properties of condensates of intrinsically disordered proteins (IDPs) is dictated by amino acid sequence and solution conditions. Because of the involvement of biomolecular condensates in cell physiology and disease, advancing our understanding of the relationship between protein sequence and phase separation (PS) may have important implications in the formulation of new therapeutic hypotheses. Here, we present CALVADOS 2, a coarse-grained model of IDPs that accurately predicts conformational properties and propensities to undergo PS for diverse sequences and solution conditions. In particular, we systematically study the effect of varying the range of the nonionic interactions and use our findings to improve the temperature scale of the model. We further optimize the residue-specific model parameters against experimental data on the conformational properties of 55 proteins, while also leveraging 70 hydrophobicity scales from the literature to avoid overfitting the training data. Extensive testing shows that the model accurately predicts chain compaction and PS propensity for sequences of diverse length and charge patterning, as well as at different temperatures and salt concentrations.
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Affiliation(s)
- Giulio Tesei
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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Liquid-liquid Phase Separation of α-Synuclein: A New Mechanistic Insight for α-Synuclein Aggregation Associated with Parkinson's Disease Pathogenesis. J Mol Biol 2023; 435:167713. [PMID: 35787838 DOI: 10.1016/j.jmb.2022.167713] [Citation(s) in RCA: 41] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 02/04/2023]
Abstract
Aberrant aggregation of the misfolded presynaptic protein, α-Synuclein (α-Syn) into Lewy body (LB) and Lewy neuritis (LN) is a major pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. Numerous studies have suggested that prefibrillar and fibrillar species of the misfolded α-Syn aggregates are responsible for cell death in PD pathogenesis. However, the precise molecular events during α-Syn aggregation, especially in the early stages, remain elusive. Emerging evidence has demonstrated that liquid-liquid phase separation (LLPS) of α-Syn occurs in the nucleation step of α-Syn aggregation, which offers an alternate non-canonical aggregation pathway in the crowded microenvironment. The liquid-like α-Syn droplets gradually undergo an irreversible liquid-to-solid phase transition into amyloid-like hydrogel entrapping oligomers and fibrils. This new mechanism of α-Syn LLPS and gel formation might represent the molecular basis of cellular toxicity associated with PD. This review aims to demonstrate the recent development of α-Syn LLPS, the underlying mechanism along with the microscopic events of aberrant phase transition. This review further discusses how several intrinsic and extrinsic factors regulate the thermodynamics and kinetics of α-Syn LLPS and co-LLPS with other proteins, which might explain the pathophysiology of α-Syn in various neurodegenerative diseases.
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He G, GrandPre T, Wilson H, Zhang Y, Jonikas MC, Wingreen NS, Wang Q. Phase-separating pyrenoid proteins form complexes in the dilute phase. Commun Biol 2023; 6:19. [PMID: 36611062 PMCID: PMC9825591 DOI: 10.1038/s42003-022-04373-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 12/13/2022] [Indexed: 01/09/2023] Open
Abstract
While most studies of biomolecular phase separation have focused on the condensed phase, relatively little is known about the dilute phase. Theory suggests that stable complexes form in the dilute phase of two-component phase-separating systems, impacting phase separation; however, these complexes have not been interrogated experimentally. We show that such complexes indeed exist, using an in vitro reconstitution system of a phase-separated organelle, the algal pyrenoid, consisting of purified proteins Rubisco and EPYC1. Applying fluorescence correlation spectroscopy (FCS) to measure diffusion coefficients, we found that complexes form in the dilute phase with or without condensates present. The majority of these complexes contain exactly one Rubisco molecule. Additionally, we developed a simple analytical model which recapitulates experimental findings and provides molecular insights into the dilute phase organization. Thus, our results demonstrate the existence of protein complexes in the dilute phase, which could play important roles in the stability, dynamics, and regulation of condensates.
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Affiliation(s)
- Guanhua He
- grid.16750.350000 0001 2097 5006Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA
| | - Trevor GrandPre
- grid.16750.350000 0001 2097 5006Department of Physics, Princeton University, Princeton, NJ 08544 USA ,grid.16750.350000 0001 2097 5006Center for the Physics of Biological Function, Princeton University, Princeton, NJ USA
| | - Hugh Wilson
- grid.16750.350000 0001 2097 5006Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 USA
| | - Yaojun Zhang
- grid.16750.350000 0001 2097 5006Center for the Physics of Biological Function, Princeton University, Princeton, NJ USA ,grid.21107.350000 0001 2171 9311Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Biophysics, Johns Hopkins University, Baltimore, MD USA
| | - Martin C. Jonikas
- grid.16750.350000 0001 2097 5006Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA ,grid.16750.350000 0001 2097 5006Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544 USA
| | - Ned S. Wingreen
- grid.16750.350000 0001 2097 5006Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA ,grid.16750.350000 0001 2097 5006Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 USA
| | - Quan Wang
- grid.16750.350000 0001 2097 5006Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544 USA ,grid.419635.c0000 0001 2203 7304Present Address: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MA 20892 USA
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