151
|
Nicy, Collepardo-Guevara R, Joseph JA, Wales DJ. Energy landscapes and heat capacity signatures for peptides correlate with phase separation propensity. QRB DISCOVERY 2023; 4:e7. [PMID: 37771761 PMCID: PMC10523320 DOI: 10.1017/qrd.2023.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/09/2023] [Accepted: 07/17/2023] [Indexed: 09/30/2023] Open
Abstract
Phase separation plays an important role in the formation of membraneless compartments within the cell and intrinsically disordered proteins with low-complexity sequences can drive this compartmentalisation. Various intermolecular forces, such as aromatic-aromatic and cation-aromatic interactions, promote phase separation. However, little is known about how the ability of proteins to phase separate under physiological conditions is encoded in their energy landscapes and this is the focus of the present investigation. Our results provide a first glimpse into how the energy landscapes of minimal peptides that contain - and cation- interactions differ from the peptides that lack amino acids with such interactions. The peaks in the heat capacity () as a function of temperature report on alternative low-lying conformations that differ significantly in terms of their enthalpic and entropic contributions. The analysis and subsequent quantification of frustration of the energy landscape suggest that the interactions that promote phase separation lead to features (peaks or inflection points) at low temperatures in . More features may occur for peptides containing residues with better phase separation propensity and the energy landscape is more frustrated for such peptides. Overall, this work links the features in the underlying single-molecule potential energy landscapes to their collective phase separation behaviour and identifies quantities ( and frustration metric) that can be utilised in soft material design.
Collapse
Affiliation(s)
- Nicy
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Rosana Collepardo-Guevara
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- Department of Physics, University of Cambridge, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Jerelle A. Joseph
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - David J. Wales
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
| |
Collapse
|
152
|
Wilson C, Lewis KA, Fitzkee NC, Hough LE, Whitten ST. ParSe 2.0: A web tool to identify drivers of protein phase separation at the proteome level. Protein Sci 2023; 32:e4756. [PMID: 37574757 PMCID: PMC10464302 DOI: 10.1002/pro.4756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 08/15/2023]
Abstract
We have developed an algorithm, ParSe, which accurately identifies from the primary sequence those protein regions likely to exhibit physiological phase separation behavior. Originally, ParSe was designed to test the hypothesis that, for flexible proteins, phase separation potential is correlated to hydrodynamic size. While our results were consistent with that idea, we also found that many different descriptors could successfully differentiate between three classes of protein regions: folded, intrinsically disordered, and phase-separating intrinsically disordered. Consequently, numerous combinations of amino acid property scales can be used to make robust predictions of protein phase separation. Built from that finding, ParSe 2.0 uses an optimal set of property scales to predict domain-level organization and compute a sequence-based prediction of phase separation potential. The algorithm is fast enough to scan the whole of the human proteome in minutes on a single computer and is equally or more accurate than other published predictors in identifying proteins and regions within proteins that drive phase separation. Here, we describe a web application for ParSe 2.0 that may be accessed through a browser by visiting https://stevewhitten.github.io/Parse_v2_FASTA to quickly identify phase-separating proteins within large sequence sets, or by visiting https://stevewhitten.github.io/Parse_v2_web to evaluate individual protein sequences.
Collapse
Affiliation(s)
- Colorado Wilson
- Department of Chemistry and BiochemistryTexas State UniversitySan MarcosTexasUSA
- Present address:
Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular BiophysicsUniversity of Texas Medical BranchGalvestonTexasUSA
| | - Karen A. Lewis
- Department of Chemistry and BiochemistryTexas State UniversitySan MarcosTexasUSA
| | - Nicholas C. Fitzkee
- Department of ChemistryMississippi State UniversityMississippi StateMississippiUSA
| | - Loren E. Hough
- Department of PhysicsUniversity of Colorado BoulderBoulderColoradoUSA
- BioFrontiers InstituteUniversity of Colorado BoulderBoulderColoradoUSA
| | - Steven T. Whitten
- Department of Chemistry and BiochemistryTexas State UniversitySan MarcosTexasUSA
| |
Collapse
|
153
|
Ho W, Huang H, Huang J. IFF: Identifying key residues in intrinsically disordered regions of proteins using machine learning. Protein Sci 2023; 32:e4739. [PMID: 37498545 PMCID: PMC10443345 DOI: 10.1002/pro.4739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 06/21/2023] [Accepted: 07/25/2023] [Indexed: 07/28/2023]
Abstract
Conserved residues in protein homolog sequence alignments are structurally or functionally important. For intrinsically disordered proteins or proteins with intrinsically disordered regions (IDRs), however, alignment often fails because they lack a steric structure to constrain evolution. Although sequences vary, the physicochemical features of IDRs may be preserved in maintaining function. Therefore, a method to retrieve common IDR features may help identify functionally important residues. We applied unsupervised contrastive learning to train a model with self-attention neuronal networks on human IDR orthologs. Parameters in the model were trained to match sequences in ortholog pairs but not in other IDRs. The trained model successfully identifies previously reported critical residues from experimental studies, especially those with an overall pattern (e.g., multiple aromatic residues or charged blocks) rather than short motifs. This predictive model can be used to identify potentially important residues in other proteins, improving our understanding of their functions. The trained model can be run directly from the Jupyter Notebook in the GitHub repository using Binder (mybinder.org). The only required input is the primary sequence. The training scripts are available on GitHub (https://github.com/allmwh/IFF). The training datasets have been deposited in an Open Science Framework repository (https://osf.io/jk29b).
Collapse
Affiliation(s)
- Wen‐Lin Ho
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung UniversityTaipeiTaiwan
| | - Hsuan‐Cheng Huang
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung UniversityTaipeiTaiwan
| | - Jie‐rong Huang
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung UniversityTaipeiTaiwan
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung UniversityTaipeiTaiwan
- Department of Life Sciences and Institute of Genome SciencesNational Yang Ming Chiao Tung UniversityTaipeiTaiwan
| |
Collapse
|
154
|
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.
Collapse
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.
| |
Collapse
|
155
|
Qin S, Zhou HX. Atomistic modeling of liquid-liquid phase equilibrium explains dependence of critical temperature on γ-crystallin sequence. Commun Biol 2023; 6:886. [PMID: 37644195 PMCID: PMC10465548 DOI: 10.1038/s42003-023-05270-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/22/2023] [Indexed: 08/31/2023] Open
Abstract
Liquid-liquid phase separation of protein solutions has regained heightened attention for its biological importance and pathogenic relevance. Coarse-grained models are limited when explaining residue-level effects on phase equilibrium. Here we report phase diagrams for γ-crystallins using atomistic modeling. The calculations were made possible by combining our FMAP method for computing chemical potentials and Brownian dynamics simulations for configurational sampling of dense protein solutions, yielding the binodal and critic temperature (Tc). We obtain a higher Tc for a known high-Tc γ-crystallin, γF, than for a low-Tc paralog, γB. The difference in Tc is corroborated by a gap in second virial coefficient. Decomposition of inter-protein interactions reveals one amino-acid substitution between γB and γF, from Ser to Trp at position 130, as the major contributor to the difference in Tc. This type of analysis enables us to link phase equilibrium to amino-acid sequence and to design mutations for altering phase equilibrium.
Collapse
Affiliation(s)
- Sanbo Qin
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Huan-Xiang Zhou
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA.
- Department of Physics, University of Illinois Chicago, Chicago, IL, 60607, USA.
| |
Collapse
|
156
|
Lesage P, Maxwell PH. A prion-like domain in Gag capsid protein drives retrotransposon particle assembly and mobility. Proc Natl Acad Sci U S A 2023; 120:e2311419120. [PMID: 37590432 PMCID: PMC10466094 DOI: 10.1073/pnas.2311419120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023] Open
Affiliation(s)
- Pascale Lesage
- Université Paris Cité, Institut de Recherche Saint Louis, Inserm, U944, CNRS, UMR7212, Paris75010, France
| | | |
Collapse
|
157
|
Zhang Y, Li S, Gong X, Chen J. Accurate Simulation of Coupling between Protein Secondary Structure and Liquid-Liquid Phase Separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.22.554378. [PMID: 37662293 PMCID: PMC10473686 DOI: 10.1101/2023.08.22.554378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Intrinsically disordered proteins (IDPs) frequently mediate liquid-liquid phase separation (LLPS) that underlies the formation of membraneless organelles. Together with theory and experiment, efficient coarse-grained (CG) simulations have been instrumental in understanding sequence-specific phase separation of IDPs. However, the widely-used Cα-only models are severely limited in capturing the peptide nature of IDPs, including backbone-mediated interactions and effects of secondary structures, in LLPS. Here, we describe a hybrid resolution (HyRes) protein model for accurate description of the backbone and transient secondary structures in LLPS. With an atomistic backbone and coarse-grained side chains, HyRes accurately predicts the residue helical propensity and chain dimension of monomeric IDPs. Using GY-23 as a model system, we show that HyRes is efficient enough for direct simulation of spontaneous phase separation, and at the same time accurate enough to resolve the effects of single mutations. HyRes simulations also successfully predict increased beta-sheet formation in the condensate, consistent with available experimental data. We further utilize HyRes to study the phase separation of TPD-43, where several disease-related mutants in the conserved region (CR) have been shown to affect residual helicities and modulate LLPS propensity. The simulations successfully recapitulate the effect of these mutants on the helicity and LLPS propensity of TDP-43 CR. Analyses reveal that the balance between backbone and sidechain-mediated interactions, but not helicity itself, actually determines LLPS propensity. We believe that the HyRes model represents an important advance in the molecular simulation of LLPS and will help elucidate the coupling between IDP transient secondary structures and phase separation.
Collapse
Affiliation(s)
| | | | - Xiping Gong
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
| |
Collapse
|
158
|
Lalmansingh JM, Keeley AT, Ruff KM, Pappu RV, Holehouse AS. SOURSOP: A Python Package for the Analysis of Simulations of Intrinsically Disordered Proteins. J Chem Theory Comput 2023; 19:5609-5620. [PMID: 37463458 PMCID: PMC11188088 DOI: 10.1021/acs.jctc.3c00190] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Conformational heterogeneity is a defining hallmark of intrinsically disordered proteins and protein regions (IDRs). The functions of IDRs and the emergent cellular phenotypes they control are associated with sequence-specific conformational ensembles. Simulations of conformational ensembles that are based on atomistic and coarse-grained models are routinely used to uncover the sequence-specific interactions that may contribute to IDR functions. These simulations are performed either independently or in conjunction with data from experiments. Functionally relevant features of IDRs can span a range of length scales. Extracting these features requires analysis routines that quantify a range of properties. Here, we describe a new analysis suite simulation analysis of unfolded regions of proteins (SOURSOP), an object-oriented and open-source toolkit designed for the analysis of simulated conformational ensembles of IDRs. SOURSOP implements several analysis routines motivated by principles in polymer physics, offering a unique collection of simple-to-use functions to characterize IDR ensembles. As an extendable framework, SOURSOP supports the development and implementation of new analysis routines that can be easily packaged and shared.
Collapse
Affiliation(s)
- Jared M. Lalmansingh
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alex T. Keeley
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana-Champaign, IL 61801, USA
| | - Kiersten M. Ruff
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Rohit V. Pappu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alex S. Holehouse
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| |
Collapse
|
159
|
Mohanty P, Shenoy J, Rizuan A, Mercado-Ortiz JF, Fawzi NL, Mittal J. A synergy between site-specific and transient interactions drives the phase separation of a disordered, low-complexity domain. Proc Natl Acad Sci U S A 2023; 120:e2305625120. [PMID: 37579155 PMCID: PMC10450430 DOI: 10.1073/pnas.2305625120] [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: 04/06/2023] [Accepted: 07/17/2023] [Indexed: 08/16/2023] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is involved in key processes in RNA metabolism and is frequently implicated in many neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia. The prion-like, disordered C-terminal domain (CTD) of TDP-43 is aggregation-prone, can undergo liquid-liquid phase separation (LLPS) in isolation, and is critical for phase separation (PS) of the full-length protein under physiological conditions. While a short conserved helical region (CR, spanning residues 319-341) promotes oligomerization and is essential for LLPS, aromatic residues in the flanking disordered regions (QN-rich, IDR1/2) are also found to play a critical role in PS and aggregation. Compared with other phase-separating proteins, TDP-43 CTD has a notably distinct sequence composition including many aliphatic residues such as methionine and leucine. Aliphatic residues were previously suggested to modulate the apparent viscosity of the resulting phases, but their direct contribution toward CTD phase separation has been relatively ignored. Using multiscale simulations coupled with in vitro saturation concentration (csat) measurements, we identified the importance of aromatic residues while also suggesting an essential role for aliphatic methionine residues in promoting single-chain compaction and LLPS. Surprisingly, NMR experiments showed that transient interactions involving phenylalanine and methionine residues in the disordered flanking regions can directly enhance site-specific, CR-mediated intermolecular association. Overall, our work highlights an underappreciated mode of biomolecular recognition, wherein both transient and site-specific hydrophobic interactions act synergistically to drive the oligomerization and phase separation of a disordered, low-complexity domain.
Collapse
Affiliation(s)
- Priyesh Mohanty
- Artie McFerrinDepartment of Chemical Engineering, Texas A&M University, College Station, TX77843
| | - Jayakrishna Shenoy
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI02912
| | - Azamat Rizuan
- Artie McFerrinDepartment of Chemical Engineering, Texas A&M University, College Station, TX77843
| | - José F. Mercado-Ortiz
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI02912
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI02912
| | - Jeetain Mittal
- Artie McFerrinDepartment of Chemical Engineering, Texas A&M University, College Station, TX77843
- Department of Chemistry, Texas A&M University, College Station, TX77843
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, TX77843
| |
Collapse
|
160
|
Tortora MMC, Brennan LD, Karpen G, Jost D. HP1-driven phase separation recapitulates the thermodynamics and kinetics of heterochromatin condensate formation. Proc Natl Acad Sci U S A 2023; 120:e2211855120. [PMID: 37549295 PMCID: PMC10438847 DOI: 10.1073/pnas.2211855120] [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: 07/11/2022] [Accepted: 06/28/2023] [Indexed: 08/09/2023] Open
Abstract
The spatial segregation of pericentromeric heterochromatin (PCH) into distinct, membrane-less nuclear compartments involves the binding of Heterochromatin Protein 1 (HP1) to H3K9me2/3-rich genomic regions. While HP1 exhibits liquid-liquid phase separation properties in vitro, its mechanistic impact on the structure and dynamics of PCH condensate formation in vivo remains largely unresolved. Here, using a minimal theoretical framework, we systematically investigate the mutual coupling between self-interacting HP1-like molecules and the chromatin polymer. We reveal that the specific affinity of HP1 for H3K9me2/3 loci facilitates coacervation in nucleo and promotes the formation of stable PCH condensates at HP1 levels far below the concentration required to observe phase separation in purified protein assays in vitro. These heterotypic HP1-chromatin interactions give rise to a strong dependence of the nucleoplasmic HP1 density on HP1-H3K9me2/3 stoichiometry, consistent with the thermodynamics of multicomponent phase separation. The dynamical cross talk between HP1 and the viscoelastic chromatin scaffold also leads to anomalously slow equilibration kinetics, which strongly depend on the genomic distribution of H3K9me2/3 domains and result in the coexistence of multiple long-lived, microphase-separated PCH compartments. The morphology of these complex coacervates is further found to be governed by the dynamic establishment of the underlying H3K9me2/3 landscape, which may drive their increasingly abnormal, aspherical shapes during cell development. These findings compare favorably to 4D microscopy measurements of HP1 condensate formation in live Drosophila embryos and suggest a general quantitative model of PCH formation based on the interplay between HP1-based phase separation and chromatin polymer mechanics.
Collapse
Affiliation(s)
- Maxime M. C. Tortora
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 69007Lyon, France
| | - Lucy D. Brennan
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Gary Karpen
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
- Department of BioEngineering and BioMedical Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Daniel Jost
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 69007Lyon, France
| |
Collapse
|
161
|
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: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [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.
Collapse
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.
| |
Collapse
|
162
|
Kaddis Maldonado R, Lambert GS, Rice BL, Sudol M, Flanagan JM, Parent LJ. The Rous sarcoma virus Gag Polyprotein Forms Biomolecular Condensates Driven by Intrinsically-disordered Regions. J Mol Biol 2023; 435:168182. [PMID: 37328094 PMCID: PMC10527454 DOI: 10.1016/j.jmb.2023.168182] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 06/07/2023] [Accepted: 06/09/2023] [Indexed: 06/18/2023]
Abstract
Biomolecular condensates (BMCs) play important roles incellular structures includingtranscription factories, splicing speckles, and nucleoli. BMCs bring together proteins and other macromolecules, selectively concentrating them so that specific reactions can occur without interference from the surrounding environment. BMCs are often made up of proteins that contain intrinsically disordered regions (IDRs), form phase-separated spherical puncta, form liquid-like droplets that undergo fusion and fission, contain molecules that are mobile, and are disrupted with phase-dissolving drugs such as 1,6-hexanediol. In addition to cellular proteins, many viruses, including influenza A, SARS-CoV-2, and human immunodeficiency virus type 1 (HIV-1) encode proteins that undergo phase separation and rely on BMC formation for replication. In prior studies of the retrovirus Rous sarcoma virus (RSV), we observed that the Gag protein forms discrete spherical puncta in the nucleus, cytoplasm, and at the plasma membrane that co-localize with viral RNA and host factors, raising the possibility that RSV Gag forms BMCs that participate in the intracellular phase of the virion assembly pathway. In our current studies, we found that Gag contains IDRs in the N-terminal (MAp2p10) and C-terminal (NC) regions of the protein and fulfills many criteria of BMCs. Although the role of BMC formation in RSV assembly requires further study, our results suggest the biophysical properties of condensates are required for the formation of Gag complexes in the nucleus and the cohesion of these complexes as they traffic through the nuclear pore, into the cytoplasm, and to the plasma membrane, where the final assembly and release of virus particles occurs.
Collapse
Affiliation(s)
- Rebecca Kaddis Maldonado
- Department of Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA; Department of Microbiology & Immunology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Gregory S Lambert
- Department of Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Breanna L Rice
- Department of Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Malgorzata Sudol
- Department of Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - John M Flanagan
- Department of Biochemistry & Molecular Biology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA
| | - Leslie J Parent
- Department of Medicine, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA; Department of Microbiology & Immunology, Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
| |
Collapse
|
163
|
Alston JJ, Soranno A, Holehouse AS. Conserved molecular recognition by an intrinsically disordered region in the absence of sequence conservation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.06.552128. [PMID: 37609146 PMCID: PMC10441348 DOI: 10.1101/2023.08.06.552128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Intrinsically disordered regions (IDRs) are critical for cellular function, yet often appear to lack sequence conservation when assessed by multiple sequence alignments. This raises the question of if and how function can be encoded and preserved in these regions despite massive sequence variation. To address this question, we have applied coarse-grained molecular dynamics simulations to investigate non-specific RNA binding of coronavirus nucleocapsid proteins. Coronavirus nucleocapsid proteins consist of multiple interspersed disordered and folded domains that bind RNA. We focussed here on the first two domains of coronavirus nucleocapsid proteins, the disordered N-terminal domain (NTD) followed by the folded RNA binding domain (RBD). While the NTD is highly variable across evolution, the RBD is structurally conserved. This combination makes the NTD-RBD a convenient model system to explore the interplay between an IDR adjacent to a folded domain, and how changes in IDR sequence can influence molecular recognition of a partner. Our results reveal a surprising degree of sequence-specificity encoded by both the composition and the precise order of the amino acids in the NTD. The presence of an NTD can - depending on the sequence - either suppress or enhance RNA binding. Despite this sensitivity, large-scale variation in NTD sequences is possible while certain sequence features are retained. Consequently, a conformationally-conserved fuzzy RNA:protein complex is found across nucleocapsid protein orthologs, despite large-scale changes in both NTD sequence and RBD surface chemistry. Taken together, these insights shed light on the ability of disordered regions to preserve functional characteristics despite their sequence variability.
Collapse
|
164
|
Saha D, Jana B. Decoupling of Interactions between Model-Charged Peptides Reveals Key Factors Responsible for Liquid-Liquid Phase Separation. J Phys Chem B 2023; 127:6656-6667. [PMID: 37480340 DOI: 10.1021/acs.jpcb.3c03087] [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: 07/24/2023]
Abstract
Liquid-liquid phase separation (LLPS) by disordered proteins has been shown to govern biological processes and cause numerous diseases. Therefore, a deeper understanding of the interactions and their variation with external factors is key to modulating the LLPS behavior of different systems and protecting proteins from pathological aggregation. In this context, we have looked at interactions between similarly charged peptides to understand the molecular features that may drive or prevent condensate formation under various conditions. We have studied dimer formation for model peptides where charged and noncharged amino acids have been placed alternatively. Using arginine and glutamic acid as the charged residues and varying the other residues with glycine, alanine, and proline to alter hydrophobicity, we have obtained the free-energy surface (FES) for the dimer formation for these systems under high salt concentration at two different temperatures using all-atom molecular dynamics simulations and the well-tempered metadynamics method. Our results indicate that a combination of effects such as hydrophobicity, arginine-arginine interactions, or water release from the solvation shell makes dimerization free energy more favorable for the positively charged peptides with lower flexibility. For the negatively charged peptides, the crucial role of water has been found in governing the FES. Systems having charged residues and phenylalanine in the peptide sequence also have been studied at high salt concentrations using unbiased simulations. In this case, only the positively charged peptides were found to aggregate through temperature-dependent hydrophobic and cation-π interactions. Overall, our study indicates that the negatively charged peptides are more likely to remain in the dilute phase under various conditions compared to the positively charged systems. The findings from our study would be helpful in designing and controlling systems to obtain LLPS behavior for therapeutic usage.
Collapse
Affiliation(s)
- Debasis Saha
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Biman Jana
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
| |
Collapse
|
165
|
Flynn AJ, Miller K, Codjoe JM, King MR, Haswell ES. Mechanosensitive ion channels MSL8, MSL9, and MSL10 have environmentally sensitive intrinsically disordered regions with distinct biophysical characteristics in vitro. PLANT DIRECT 2023; 7:e515. [PMID: 37547488 PMCID: PMC10400277 DOI: 10.1002/pld3.515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 08/08/2023]
Abstract
Intrinsically disordered protein regions (IDRs) are highly dynamic sequences that rapidly sample a collection of conformations over time. In the past several decades, IDRs have emerged as a major component of many proteomes, comprising ~30% of all eukaryotic protein sequences. Proteins with IDRs function in a wide range of biological pathways and are notably enriched in signaling cascades that respond to environmental stresses. Here, we identify and characterize intrinsic disorder in the soluble cytoplasmic N-terminal domains of MSL8, MSL9, and MSL10, three members of the MscS-like (MSL) family of mechanosensitive ion channels. In plants, MSL channels are proposed to mediate cell and organelle osmotic homeostasis. Bioinformatic tools unanimously predicted that the cytosolic N-termini of MSL channels are intrinsically disordered. We examined the N-terminus of MSL10 (MSL10N) as an exemplar of these IDRs and circular dichroism spectroscopy confirms its disorder. MSL10N adopted a predominately helical structure when exposed to the helix-inducing compound trifluoroethanol (TFE). Furthermore, in the presence of molecular crowding agents, MSL10N underwent structural changes and exhibited alterations to its homotypic interaction favorability. Lastly, interrogations of collective behavior via in vitro imaging of condensates indicated that MSL8N, MSL9N, and MSL10N have sharply differing propensities for self-assembly into condensates, both inherently and in response to salt, temperature, and molecular crowding. Taken together, these data establish the N-termini of MSL channels as intrinsically disordered regions with distinct biophysical properties and the potential to respond uniquely to changes in their physiochemical environment.
Collapse
Affiliation(s)
- Aidan J. Flynn
- Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
- NSF Center for Engineering Mechanobiology, Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
- Department of Biochemistry and BiophysicsWashington University in St. LouisSt. LouisMissouriUSA
| | - Kari Miller
- Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
- NSF Center for Engineering Mechanobiology, Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
| | - Jennette M. Codjoe
- Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
- NSF Center for Engineering Mechanobiology, Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
| | - Matthew R. King
- Department of Biomedical EngineeringWashington University in St. LouisSt. LouisMissouriUSA
| | - Elizabeth S. Haswell
- Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
- NSF Center for Engineering Mechanobiology, Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
| |
Collapse
|
166
|
Miao Y, Guo X, Zhu K, Zhao W. Biomolecular condensates tunes immune signaling at the Host-Pathogen interface. CURRENT OPINION IN PLANT BIOLOGY 2023; 74:102374. [PMID: 37148673 DOI: 10.1016/j.pbi.2023.102374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 04/06/2023] [Accepted: 04/07/2023] [Indexed: 05/08/2023]
Abstract
Membraneless organelles participate in diverse spatiotemporal regulation of cellular signal transduction by recruiting necessary signaling factors. During host-pathogen interactions, the plasma membrane (PM) at the interface between the plant and microbes serves as a central platform for forming multicomponent immune signaling hubs. The macromolecular condensation of the immune complex and regulators is important in regulating immune signaling outputs regarding strength, timing, and crosstalk between signaling pathways. This review discusses mechanisms that regulate specific and crosstalk of plant immune signal transduction pathways through macromolecular assembly and condensation.
Collapse
Affiliation(s)
- Yansong Miao
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore; Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 636921, Singapore.
| | - Xiangfu Guo
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 70 Nanyang Drive, 637457, Singapore
| | - Kexin Zhu
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Wenting Zhao
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 70 Nanyang Drive, 637457, Singapore; Institute for Digital Molecular Analytics and Science, Nanyang Technological University, 636921, Singapore
| |
Collapse
|
167
|
Arakawa K, Hirose T, Inada T, Ito T, Kai T, Oyama M, Tomari Y, Yoda T, Nakagawa S. Nondomain biopolymers: Flexible molecular strategies to acquire biological functions. Genes Cells 2023; 28:539-552. [PMID: 37249032 DOI: 10.1111/gtc.13050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 05/15/2023] [Accepted: 05/16/2023] [Indexed: 05/31/2023]
Abstract
A long-standing assumption in molecular biology posits that the conservation of protein and nucleic acid sequences emphasizes the functional significance of biomolecules. These conserved sequences fold into distinct secondary and tertiary structures, enable highly specific molecular interactions, and regulate complex yet organized molecular processes within living cells. However, recent evidence suggests that biomolecules can also function through primary sequence regions that lack conservation across species or gene families. These regions typically do not form rigid structures, and their inherent flexibility is critical for their functional roles. This review examines the emerging roles and molecular mechanisms of "nondomain biomolecules," whose functions are not easily predicted due to the absence of conserved functional domains. We propose the hypothesis that both domain- and nondomain-type molecules work together to enable flexible and efficient molecular processes within the highly crowded intracellular environment.
Collapse
Grants
- 21H05273 Ministry of Education, Culture, Sports, Science and Technology
- 21H05274 Ministry of Education, Culture, Sports, Science and Technology
- 21H05275 Ministry of Education, Culture, Sports, Science and Technology
- 21H05276 Ministry of Education, Culture, Sports, Science and Technology
- 21H05277 Ministry of Education, Culture, Sports, Science and Technology
- 21H05278 Ministry of Education, Culture, Sports, Science and Technology
- 21H05279 Ministry of Education, Culture, Sports, Science and Technology
- 21H05280 Ministry of Education, Culture, Sports, Science and Technology
- 21H05281 Ministry of Education, Culture, Sports, Science and Technology
- 21H05282 Ministry of Education, Culture, Sports, Science and Technology
Collapse
Affiliation(s)
- Kazuharu Arakawa
- Institute for Advanced Biosciences, Keio University, Tokyo, Japan
| | - Tetsuro Hirose
- RNA Biofunction Laboratory, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Toshifumi Inada
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Takuhiro Ito
- Laboratory for Translation Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Japan
| | - Toshie Kai
- Germline Biology Laboratory, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Masaaki Oyama
- Medical Proteomics Laboratory, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yukihide Tomari
- Laboratory of RNA Function, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo, Japan
| | - Takao Yoda
- Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Shinichi Nakagawa
- RNA Biology Laboratory, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| |
Collapse
|
168
|
Saar KL, Qian D, Good LL, Morgunov AS, Collepardo-Guevara R, Best RB, Knowles TPJ. Theoretical and Data-Driven Approaches for Biomolecular Condensates. Chem Rev 2023; 123:8988-9009. [PMID: 37171907 PMCID: PMC10375482 DOI: 10.1021/acs.chemrev.2c00586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Indexed: 05/14/2023]
Abstract
Biomolecular condensation processes are increasingly recognized as a fundamental mechanism that living cells use to organize biomolecules in time and space. These processes can lead to the formation of membraneless organelles that enable cells to perform distinct biochemical processes in controlled local environments, thereby supplying them with an additional degree of spatial control relative to that achieved by membrane-bound organelles. This fundamental importance of biomolecular condensation has motivated a quest to discover and understand the molecular mechanisms and determinants that drive and control this process. Within this molecular viewpoint, computational methods can provide a unique angle to studying biomolecular condensation processes by contributing the resolution and scale that are challenging to reach with experimental techniques alone. In this Review, we focus on three types of dry-lab approaches: theoretical methods, physics-driven simulations and data-driven machine learning methods. We review recent progress in using these tools for probing biomolecular condensation across all three fields and outline the key advantages and limitations of each of the approaches. We further discuss some of the key outstanding challenges that we foresee the community addressing next in order to develop a more complete picture of the molecular driving forces behind biomolecular condensation processes and their biological roles in health and disease.
Collapse
Affiliation(s)
- Kadi L. Saar
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Transition
Bio Ltd., Cambridge, United Kingdom
| | - Daoyuan Qian
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Lydia L. Good
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Laboratory
of Chemical Physics, National Institute of Diabetes and Digestive
and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United States
| | - Alexey S. Morgunov
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Rosana Collepardo-Guevara
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Department
of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Robert B. Best
- Laboratory
of Chemical Physics, National Institute of Diabetes and Digestive
and Kidney Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United States
| | - Tuomas P. J. Knowles
- Yusuf
Hamied Department of Chemistry, University
of Cambridge, Cambridge CB2 1EW, United Kingdom
- Cavendish
Laboratory, Department of Physics, University
of Cambridge, Cambridge CB3 0HE, United Kingdom
| |
Collapse
|
169
|
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.
Collapse
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
| |
Collapse
|
170
|
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.
Collapse
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
| |
Collapse
|
171
|
Lushpinskaia IP, Flores-Solis D, Zweckstetter M. Structure and phase separation of the C-terminal domain of RNA polymerase II. Biol Chem 2023; 404:839-844. [PMID: 37331973 DOI: 10.1515/hsz-2023-0136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 06/01/2023] [Indexed: 06/20/2023]
Abstract
The repetitive heptads in the C-terminal domain (CTD) of RPB1, the largest subunit of RNA Polymerase II (Pol II), play a critical role in the regulation of Pol II-based transcription. Recent findings on the structure of the CTD in the pre-initiation complex determined by cryo-EM and the novel phase separation properties of key transcription components offers an expanded mechanistic interpretation of the spatiotemporal distribution of Pol II during transcription. Current experimental evidence further suggests an exquisite balance between CTD's local structure and an array of multivalent interactions that drive phase separation of Pol II and thus shape its transcriptional activity.
Collapse
Affiliation(s)
- Irina P Lushpinskaia
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, D-35075 Göttingen, Germany
| | - David Flores-Solis
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, D-35075 Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold Straße 3A, D-35075 Göttingen, Germany
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, D-37077 Göttingen, Germany
| |
Collapse
|
172
|
Chung CI, Yang J, Shu X. Chemogenetic Minitool for Dissecting the Roles of Protein Phase Separation. ACS CENTRAL SCIENCE 2023; 9:1466-1479. [PMID: 37521779 PMCID: PMC10375881 DOI: 10.1021/acscentsci.3c00251] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Indexed: 08/01/2023]
Abstract
Biomolecular condensate is an emerging structural entity that regulates various cellular processes. Recent studies have discovered the phase-separation (PS) capability of several transcription factors (TFs) including YAP/TAZ upon biological stimuli, which provide new mechanisms of gene regulation. However, it remains mostly unanswered as to whether PS from a diffuse state to a phase-separated state promotes gene transcription. To address this question, we have designed a chemogenetic tool, dubbed SPARK-ON, which manipulates the PS of YAP and TAZ without a biological stimulus, forming condensates that are transcriptionally active, containing the DNA-binding partner TEAD, genomic DNA, transcriptional machinery, and nascent RNA. Most importantly, PS of TAZ increases the transcription of its target genes. Therefore, our data indicate that PS promotes gene transcription of TAZ. SPARK-ON is advantageous to current mutagenesis-based approaches that are often problematic when mutagenesis affects the transcriptional activity of a TF. Furthermore, protein abundance levels also affect gene transcription, but PS depends on protein abundance because PS occurs only when the protein level is above a saturation concentration. SPARK-ON decouples PS from protein abundance levels without introducing mutations and thus will find important applications in understanding the biological roles of PS for many TFs and other biomolecular condensates.
Collapse
Affiliation(s)
- Chan-I Chung
- Department
of Pharmaceutical Chemistry, University
of California—San Francisco, San Francisco, California 94158, United States
- Cardiovascular
Research Institute, University of California—San
Francisco, San Francisco, California 94158, United States
| | - Junjiao Yang
- Department
of Pharmaceutical Chemistry, University
of California—San Francisco, San Francisco, California 94158, United States
- Cardiovascular
Research Institute, University of California—San
Francisco, San Francisco, California 94158, United States
| | - Xiaokun Shu
- Department
of Pharmaceutical Chemistry, University
of California—San Francisco, San Francisco, California 94158, United States
- Cardiovascular
Research Institute, University of California—San
Francisco, San Francisco, California 94158, United States
- Helen Diller
Family Comprehensive Cancer Center, University
of California—San Francisco, San Francisco, California 94158, United States
| |
Collapse
|
173
|
Sanchez-Burgos I, Herriott L, Collepardo-Guevara R, Espinosa JR. Surfactants or scaffolds? RNAs of varying lengths control the thermodynamic stability of condensates differently. Biophys J 2023; 122:2973-2987. [PMID: 36883003 PMCID: PMC10398262 DOI: 10.1016/j.bpj.2023.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 02/23/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Biomolecular condensates, thought to form via liquid-liquid phase separation of intracellular mixtures, are multicomponent systems that can include diverse types of proteins and RNAs. RNA is a critical modulator of RNA-protein condensate stability, as it induces an RNA concentration-dependent reentrant phase transition-increasing stability at low RNA concentrations and decreasing it at high concentrations. Beyond concentration, RNAs inside condensates can be heterogeneous in length, sequence, and structure. Here, we use multiscale simulations to understand how different RNA parameters interact with one another to modulate the properties of RNA-protein condensates. To do so, we perform residue/nucleotide resolution coarse-grained molecular dynamics simulations of multicomponent RNA-protein condensates containing RNAs of different lengths and concentrations, and either FUS or PR25 proteins. Our simulations reveal that RNA length regulates the reentrant phase behavior of RNA-protein condensates: increasing RNA length sensitively rises the maximum value that the critical temperature of the mixture reaches, and the maximum concentration of RNA that the condensate can incorporate before beginning to become unstable. Strikingly, RNAs of different lengths are organized heterogeneously inside condensates, which allows them to enhance condensate stability via two distinct mechanisms: shorter RNA chains accumulate at the condensate's surface acting as natural biomolecular surfactants, while longer RNA chains concentrate inside the core to saturate their bonds and enhance the density of molecular connections in the condensate. Using a patchy particle model, we additionally demonstrate that the combined impact of RNA length and concentration on condensate properties is dictated by the valency, binding affinity, and polymer length of the various biomolecules involved. Our results postulate that diversity on RNA parameters within condensates allows RNAs to increase condensate stability by fulfilling two different criteria: maximizing enthalpic gain and minimizing interfacial free energy; hence, RNA diversity should be considered when assessing the impact of RNA on biomolecular condensates regulation.
Collapse
Affiliation(s)
- Ignacio Sanchez-Burgos
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Lara Herriott
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Rosana Collepardo-Guevara
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom; Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
| | - Jorge R Espinosa
- Maxwell Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Departament of Chemical Physics, Faculty of Chemical Sciences, Universidad Complutense de Madrid, Madrid, Spain.
| |
Collapse
|
174
|
Koren G, Meir S, Holschuh L, Mertens HDT, Ehm T, Yahalom N, Golombek A, Schwartz T, Svergun DI, Saleh OA, Dzubiella J, Beck R. Intramolecular structural heterogeneity altered by long-range contacts in an intrinsically disordered protein. Proc Natl Acad Sci U S A 2023; 120:e2220180120. [PMID: 37459524 PMCID: PMC10372579 DOI: 10.1073/pnas.2220180120] [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: 11/27/2022] [Accepted: 06/02/2023] [Indexed: 07/20/2023] Open
Abstract
Short-range interactions and long-range contacts drive the 3D folding of structured proteins. The proteins' structure has a direct impact on their biological function. However, nearly 40% of the eukaryotes proteome is composed of intrinsically disordered proteins (IDPs) and protein regions that fluctuate between ensembles of numerous conformations. Therefore, to understand their biological function, it is critical to depict how the structural ensemble statistics correlate to the IDPs' amino acid sequence. Here, using small-angle X-ray scattering and time-resolved Förster resonance energy transfer (trFRET), we study the intramolecular structural heterogeneity of the neurofilament low intrinsically disordered tail domain (NFLt). Using theoretical results of polymer physics, we find that the Flory scaling exponent of NFLt subsegments correlates linearly with their net charge, ranging from statistics of ideal to self-avoiding chains. Surprisingly, measuring the same segments in the context of the whole NFLt protein, we find that regardless of the peptide sequence, the segments' structural statistics are more expanded than when measured independently. Our findings show that while polymer physics can, to some level, relate the IDP's sequence to its ensemble conformations, long-range contacts between distant amino acids play a crucial role in determining intramolecular structures. This emphasizes the necessity of advanced polymer theories to fully describe IDPs ensembles with the hope that it will allow us to model their biological function.
Collapse
Affiliation(s)
- Gil Koren
- The School of Physics and Astronomy, Department of Condensed Matter, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
| | - Sagi Meir
- The School of Physics and Astronomy, Department of Condensed Matter, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
| | - Lennard Holschuh
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universit Freiburg, FreiburgD-79104, Germany
| | | | - Tamara Ehm
- The School of Physics and Astronomy, Department of Condensed Matter, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität, MünchenD-80539, Germany
| | - Nadav Yahalom
- The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences and Tel Aviv University Center for Light–Matter Interaction, Tel Aviv University, Tel Aviv6997801, Israel
| | - Adina Golombek
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences and Tel Aviv University Center for Light–Matter Interaction, Tel Aviv University, Tel Aviv6997801, Israel
| | - Tal Schwartz
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences and Tel Aviv University Center for Light–Matter Interaction, Tel Aviv University, Tel Aviv6997801, Israel
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg22607, Germany
| | - Omar A. Saleh
- BMSE Program, University of California, Santa Barbara, CA93110
- Materials Department, University of California, Santa Barbara, CA93110
| | - Joachim Dzubiella
- Applied Theoretical Physics-Computational Physics, Physikalisches Institut, Albert-Ludwigs-Universit Freiburg, FreiburgD-79104, Germany
- Cluster of Excellence livMatS @ FIT–Freiburg Center for Interactive Materials and Bioinspired Technologies, Albert-Ludwigs-Universit Freiburg, FreiburgD-79104, Germany
| | - Roy Beck
- The School of Physics and Astronomy, Department of Condensed Matter, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv69978, Israel
| |
Collapse
|
175
|
Ramirez DA, Hough LE, Shirts MR. Coiled-coil domains are sufficient to drive liquid-liquid phase separation of proteins in molecular models. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543124. [PMID: 37398035 PMCID: PMC10312653 DOI: 10.1101/2023.05.31.543124] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Liquid-liquid phase separation (LLPS) is thought to be a main driving force in the formation of membraneless organelles. Examples of such organelles include the centrosome, central spindle, and stress granules. Recently, it has been shown that coiled-coil (CC) proteins, such as the centrosomal proteins pericentrin, spd-5, and centrosomin, might be capable of LLPS. CC domains have physical features that could make them the drivers of LLPS, but it is unknown if they play a direct role in the process. We developed a coarse-grained simulation framework for investigating the LLPS propensity of CC proteins, in which interactions which support LLPS arise solely from CC domains. We show, using this framework, that the physical features of CC domains are sufficient to drive LLPS of proteins. The framework is specifically designed to investigate how the number of CC domains, as well as multimerization state of CC domains, can affect LLPS. We show that small model proteins with as few as two CC domains can phase separate. Increasing the number of CC domains up to four per protein can somewhat increase LLPS propensity. We demonstrate that trimer-forming and tetramer-forming CC domains have a dramatically higher LLPS propensity than dimer-forming coils, which shows that multimerization state has a greater effect on LLPS than the number of CC domains per protein. These data support the hypothesis of CC domains as drivers of protein LLPS, and has implications in future studies to identify the LLPS-driving regions of centrosomal and central spindle proteins.
Collapse
Affiliation(s)
| | - Loren E. Hough
- Department of Physics and BioFrontiers Institute, University of Colorado Boulder, Boulder CO, 80309
| | - Michael R. Shirts
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder CO, 80309
| |
Collapse
|
176
|
Zhang Z, Huang G, Song Z, Gatch AJ, Ding F. Amyloid Aggregation and Liquid-Liquid Phase Separation from the Perspective of Phase Transitions. J Phys Chem B 2023; 127:6241-6250. [PMID: 37414583 PMCID: PMC10404378 DOI: 10.1021/acs.jpcb.3c01426] [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] [Indexed: 07/08/2023]
Abstract
Amyloid aggregation describes the aberrant self-assembly of peptides into ordered fibrils characterized by cross-β spine cores and is associated with many neurodegenerative diseases and Type 2 diabetes. Oligomers, populated during the early stage of aggregation, are found to be more cytotoxic than mature fibrils. Recently, many amyloidogenic peptides have been reported to undergo liquid-liquid phase separation (LLPS)─a biological process important for the compartmentalization of biomolecules in living cells─prior to fibril formation. Understanding the relationship between LLPS and amyloid aggregation, especially the formation of oligomers, is essential for uncovering disease mechanisms and mitigating amyloid toxicity. In this Perspective, available theories and models of amyloid aggregation and LLPS are first briefly reviewed. By drawing analogies to gas, liquid, and solid phases in thermodynamics, a phase diagram of protein monomer, droplet, and fibril states separated by coexistence lines can be inferred. Due to the high free energy barrier of fibrillization kinetically delaying the formation of fibril seeds out of the droplets, a "hidden" monomer-droplet coexistence line extends into the fibril phase. Amyloid aggregation can then be described as the equilibration process from the initial "out-of-equilibrium" state of a homogeneous solution of monomers to the final equilibrium state of stable amyloid fibrils coexisting with monomers and/or droplets via the formation of metastable or stable droplets as the intermediates. The relationship between droplets and oligomers is also discussed. We suggest that the droplet formation of LLPS should be considered in future studies of amyloid aggregation, which may help to better understand the aggregation process and develop therapeutic strategies to mitigate amyloid toxicity.
Collapse
Affiliation(s)
- Zhenzhen Zhang
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Gangtong Huang
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Zhiyuan Song
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Adam J. Gatch
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, United States
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| |
Collapse
|
177
|
Polyansky AA, Gallego LD, Efremov RG, Köhler A, Zagrovic B. Protein compactness and interaction valency define the architecture of a biomolecular condensate across scales. eLife 2023; 12:e80038. [PMID: 37470705 PMCID: PMC10406433 DOI: 10.7554/elife.80038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/18/2023] [Indexed: 07/21/2023] Open
Abstract
Non-membrane-bound biomolecular condensates have been proposed to represent an important mode of subcellular organization in diverse biological settings. However, the fundamental principles governing the spatial organization and dynamics of condensates at the atomistic level remain unclear. The Saccharomyces cerevisiae Lge1 protein is required for histone H2B ubiquitination and its N-terminal intrinsically disordered fragment (Lge11-80) undergoes robust phase separation. This study connects single- and multi-chain all-atom molecular dynamics simulations of Lge11-80 with the in vitro behavior of Lge11-80 condensates. Analysis of modeled protein-protein interactions elucidates the key determinants of Lge11-80 condensate formation and links configurational entropy, valency, and compactness of proteins inside the condensates. A newly derived analytical formalism, related to colloid fractal cluster formation, describes condensate architecture across length scales as a function of protein valency and compactness. In particular, the formalism provides an atomistically resolved model of Lge11-80 condensates on the scale of hundreds of nanometers starting from individual protein conformers captured in simulations. The simulation-derived fractal dimensions of condensates of Lge11-80 and its mutants agree with their in vitro morphologies. The presented framework enables a multiscale description of biomolecular condensates and embeds their study in a wider context of colloid self-organization.
Collapse
Affiliation(s)
- Anton A Polyansky
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational BiologyViennaAustria
| | - Laura D Gallego
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- Medical University of Vienna, Center for Medical BiochemistryViennaAustria
| | - Roman G Efremov
- MM Shemyakin and Yu A Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of SciencesMoscowRussian Federation
| | - Alwin Köhler
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- Medical University of Vienna, Center for Medical BiochemistryViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell BiologyViennaAustria
| | - Bojan Zagrovic
- Max Perutz Labs, Vienna Biocenter Campus (VBC)ViennaAustria
- University of Vienna, Center for Molecular Biology, Department of Structural and Computational BiologyViennaAustria
| |
Collapse
|
178
|
Galvanetto N, Ivanović MT, Chowdhury A, Sottini A, Nüesch MF, Nettels D, Best RB, Schuler B. Extreme dynamics in a biomolecular condensate. Nature 2023:10.1038/s41586-023-06329-5. [PMID: 37468629 DOI: 10.1038/s41586-023-06329-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 06/14/2023] [Indexed: 07/21/2023]
Abstract
Proteins and nucleic acids can phase-separate in the cell to form concentrated biomolecular condensates1-4. The functions of condensates span many length scales: they modulate interactions and chemical reactions at the molecular scale5, organize biochemical processes at the mesoscale6 and compartmentalize cells4. Understanding the underlying mechanisms of these processes will require detailed knowledge of the rich dynamics across these scales7. The mesoscopic dynamics of biomolecular condensates have been extensively characterized8, but their behaviour at the molecular scale has remained more elusive. Here, as an example of biomolecular phase separation, we study complex coacervates of two highly and oppositely charged disordered human proteins9. Their dense phase is 1,000 times more concentrated than the dilute phase, and the resulting percolated interaction network10 leads to a bulk viscosity 300 times greater than that of water. However, single-molecule spectroscopy optimized for measurements within individual droplets reveals that at the molecular scale, the disordered proteins remain exceedingly dynamic, with their chain configurations interconverting on submicrosecond timescales. Massive all-atom molecular dynamics simulations reproduce the experimental observations and explain this apparent discrepancy: the underlying interactions between individual charged side chains are short-lived and exchange on a pico- to nanosecond timescale. Our results indicate that, despite the high macroscopic viscosity of phase-separated systems, local biomolecular rearrangements required for efficient reactions at the molecular scale can remain rapid.
Collapse
Affiliation(s)
- Nicola Galvanetto
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
- Department of Physics, University of Zurich, Zurich, Switzerland.
| | - Miloš T Ivanović
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
| | - Aritra Chowdhury
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Andrea Sottini
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Mark F Nüesch
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
- Department of Physics, University of Zurich, Zurich, Switzerland.
| |
Collapse
|
179
|
Guo G, Wang X, Zhang Y, Li T. Sequence variations of phase-separating proteins and resources for studying biomolecular condensates. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1119-1132. [PMID: 37464880 PMCID: PMC10423696 DOI: 10.3724/abbs.2023131] [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: 04/13/2023] [Accepted: 06/06/2023] [Indexed: 07/20/2023] Open
Abstract
Phase separation (PS) is an important mechanism underlying the formation of biomolecular condensates. Physiological condensates are associated with numerous biological processes, such as transcription, immunity, signaling, and synaptic transmission. Changes in particular amino acids or segments can disturb the protein's phase behavior and interactions with other biomolecules in condensates. It is thus presumed that variations in the phase-separating-prone domains can significantly impact the properties and functions of condensates. The dysfunction of condensates contributes to a number of pathological processes. Pharmacological perturbation of these condensates is proposed as a promising way to restore physiological states. In this review, we characterize the variations observed in PS proteins that lead to aberrant biomolecular compartmentalization. We also showcase recent advancements in bioinformatics of membraneless organelles (MLOs), focusing on available databases useful for screening PS proteins and describing endogenous condensates, guiding researchers to seek the underlying pathogenic mechanisms of biomolecular condensates.
Collapse
Affiliation(s)
- Gaigai Guo
- Department of Biomedical InformaticsSchool of Basic Medical SciencesPeking University Health Science CenterBeijing100191China
| | - Xinxin Wang
- Department of Biomedical InformaticsSchool of Basic Medical SciencesPeking University Health Science CenterBeijing100191China
| | - Yi Zhang
- Department of Biomedical InformaticsSchool of Basic Medical SciencesPeking University Health Science CenterBeijing100191China
| | - Tingting Li
- Department of Biomedical InformaticsSchool of Basic Medical SciencesPeking University Health Science CenterBeijing100191China
- Key Laboratory for NeuroscienceMinistry of Education/National Health Commission of ChinaPeking UniversityBeijing100191China
| |
Collapse
|
180
|
Zytkiewicz E, Shkel IA, Cheng X, Rupanya A, McClure K, Karim R, Yang S, Yang F, Record MT. Quantifying Amide-Aromatic Interactions at Molecular and Atomic Levels: Experimentally-determined Enthalpic and Entropic Contributions to Interactions of Amide sp 2 O, N, C and sp 3 C Unified Atoms with Naphthalene sp 2 C Atoms in Water. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.12.548600. [PMID: 37503153 PMCID: PMC10370101 DOI: 10.1101/2023.07.12.548600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
In addition to amide hydrogen bonds and the hydrophobic effect, interactions involving π-bonded sp 2 atoms of amides, aromatics and other groups occur in protein self-assembly processes including folding, oligomerization and condensate formation. These interactions also occur in aqueous solutions of amide and aromatic compounds, where they can be quantified. Previous analysis of thermodynamic coefficients quantifying net-favorable interactions of amide compounds with other amides and aromatics revealed that interactions of amide sp 2 O with amide sp 2 N unified atoms (presumably C=O···H-N hydrogen bonds) and amide/aromatic sp 2 C (lone pair-π, n-π * ) are particularly favorable. Sp 3 C-sp 3 C (hydrophobic), sp 3 C-sp 2 C (hydrophobic, CH-π), sp 2 C-sp 2 C (hydrophobic, π-π) and sp 3 C-sp 2 N interactions are favorable, sp 2 C-sp 2 N interactions are neutral, while sp 2 O-sp 2 O and sp 2 N-sp 2 N self-interactions and sp 2 O-sp 3 C interactions are unfavorable. Here, from determinations of favorable effects of fourteen amides on naphthalene solubility at 10, 25 and 45 °C, we dissect amide-aromatic interaction free energies into enthalpic and entropic contributions and find these vary systematically with amide composition. Analysis of these results yields enthalpic and entropic contributions to intrinsic strengths of interactions of amide sp 2 O, sp 2 N, sp 2 C and sp 3 C unified atoms with aromatic sp 2 C atoms. For each interaction, enthalpic and entropic contributions have the same sign and are much larger in magnitude than the interaction free energy itself. The amide sp 2 O-aromatic sp 2 C interaction is enthalpy-driven and entropically unfavorable, consistent with direct chemical interaction (e.g. lone pair-π) while amide sp 3 C- and sp 2 C-aromatic sp 2 C interactions are entropy-driven and enthalpically unfavorable, consistent with hydrophobic effects. These findings are relevant for interactions involving π-bonded sp 2 atoms in protein processes. Table of Contents Graphic
Collapse
Affiliation(s)
- Emily Zytkiewicz
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Irina A. Shkel
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Xian Cheng
- Biophysics Program, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Anuchit Rupanya
- Department of Chemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Kate McClure
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Rezwana Karim
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Sumin Yang
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - Felix Yang
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| | - M. Thomas Record
- Department of Biochemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
- Biophysics Program, University of Wisconsin – Madison, Madison, Wisconsin 53706
- Department of Chemistry, University of Wisconsin – Madison, Madison, Wisconsin 53706
| |
Collapse
|
181
|
Malhotra I, Potoyan DA. Re-entrant transitions of locally stiff RNA chains in the presence of polycations leads to gelated architectures. SOFT MATTER 2023. [PMID: 37449795 PMCID: PMC10369498 DOI: 10.1039/d3sm00320e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
The liquid-liquid phase separation of protein and nucleic acid mixtures drives the formation of numerous membraneless compartments in cells. Temperature variation is commonly used for mapping condensate phase diagrams, which often display unique upper critical temperatures. Recent report on peptide-RNA mixtures has shown the existence of lower and upper critical solution temperatures, highlighting the importance of temperature-dependent solvent and ion-mediated forces. In the present work, we employ residue-level coarse-grained models of RNA and polycation peptide chains for simulating temperature-induced re-entrant transitions and shedding light on the role played by mobile ions, temperature-dependent dielectric permittivity, and local chain stiffness. We show that differences in bending rigidity can significantly modulate condensate topology leading to the formation of gelated or fibril like architectures. The study also finds that temperature dependence of water permittivity is generally sufficient for recapitulating experimentally observed closed loop and LCST phase diagrams of highly charged protein-RNA mixtures. However, we find that similar-looking closed-loop phase diagrams can correspond to vastly different condensate topologies.
Collapse
Affiliation(s)
- Isha Malhotra
- Department of Chemistry, Iowa State University, Ames, Iowa 50014, USA.
| | - Davit A Potoyan
- Department of Chemistry, Iowa State University, Ames, Iowa 50014, USA.
| |
Collapse
|
182
|
Yuan F, Lee CT, Sangani A, Houser JR, Wang L, Lafer EM, Rangamani P, Stachowiak JC. The ins and outs of membrane bending by intrinsically disordered proteins. SCIENCE ADVANCES 2023; 9:eadg3485. [PMID: 37418523 PMCID: PMC10328403 DOI: 10.1126/sciadv.adg3485] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 06/07/2023] [Indexed: 07/09/2023]
Abstract
Membrane curvature is essential to diverse cellular functions. While classically attributed to structured domains, recent work illustrates that intrinsically disordered proteins are also potent drivers of membrane bending. Specifically, repulsive interactions among disordered domains drive convex bending, while attractive interactions drive concave bending, creating membrane-bound, liquid-like condensates. How might disordered domains that contain both repulsive and attractive domains affect curvature? Here, we examined chimeras that combined attractive and repulsive interactions. When the attractive domain was closer to the membrane, its condensation amplified steric pressure among repulsive domains, leading to convex curvature. In contrast, when the repulsive domain was closer to the membrane, attractive interactions dominated, resulting in concave curvature. Further, a transition from convex to concave curvature occurred with increasing ionic strength, which reduced repulsion while enhancing condensation. In agreement with a simple mechanical model, these results illustrate a set of design rules for membrane bending by disordered proteins.
Collapse
Affiliation(s)
- Feng Yuan
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Christopher T. Lee
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
| | - Arjun Sangani
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Justin R. Houser
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Liping Wang
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Eileen M. Lafer
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
| | - Jeanne C. Stachowiak
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
| |
Collapse
|
183
|
Townley BA, Buerer L, Tsao N, Bacolla A, Mansoori F, Rusanov T, Clark N, Goodarzi N, Schmidt N, Srivatsan SN, Sun H, Sample RA, Brickner JR, McDonald D, Tsai MS, Walter MJ, Wozniak DF, Holehouse AS, Pena V, Tainer JA, Fairbrother WG, Mosammaparast N. A functional link between lariat debranching enzyme and the intron-binding complex is defective in non-photosensitive trichothiodystrophy. Mol Cell 2023; 83:2258-2275.e11. [PMID: 37369199 PMCID: PMC10483886 DOI: 10.1016/j.molcel.2023.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 03/25/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023]
Abstract
The pre-mRNA life cycle requires intron processing; yet, how intron-processing defects influence splicing and gene expression is unclear. Here, we find that TTDN1/MPLKIP, which is encoded by a gene implicated in non-photosensitive trichothiodystrophy (NP-TTD), functionally links intron lariat processing to spliceosomal function. The conserved TTDN1 C-terminal region directly binds lariat debranching enzyme DBR1, whereas its N-terminal intrinsically disordered region (IDR) binds the intron-binding complex (IBC). TTDN1 loss, or a mutated IDR, causes significant intron lariat accumulation, as well as splicing and gene expression defects, mirroring phenotypes observed in NP-TTD patient cells. A Ttdn1-deficient mouse model recapitulates intron-processing defects and certain neurodevelopmental phenotypes seen in NP-TTD. Fusing DBR1 to the TTDN1 IDR is sufficient to recruit DBR1 to the IBC and circumvents the functional requirement for TTDN1. Collectively, our findings link RNA lariat processing with splicing outcomes by revealing the molecular function of TTDN1.
Collapse
Affiliation(s)
- Brittany A Townley
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Luke Buerer
- Center for Computational Molecular Biology, Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912, USA
| | - Ning Tsao
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Albino Bacolla
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Fadhel Mansoori
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Timur Rusanov
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Nathanial Clark
- Center for Computational Molecular Biology, Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912, USA
| | - Negar Goodarzi
- Mechanisms and Regulation of Splicing Research Group, The Institute of Cancer Research, London, UK
| | - Nicolas Schmidt
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Hua Sun
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Reilly A Sample
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Joshua R Brickner
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Drew McDonald
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Miaw-Sheue Tsai
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Matthew J Walter
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - David F Wozniak
- Department of Psychiatry, Intellectual and Developmental Disabilities Research Center, Washington University School of Medicine, St. Louis, MO 63110-1093, USA
| | - Alex S Holehouse
- Department of Biochemistry & Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA; Center for Science and Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Vladimir Pena
- Mechanisms and Regulation of Splicing Research Group, The Institute of Cancer Research, London, UK
| | - John A Tainer
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA; Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - William G Fairbrother
- Center for Computational Molecular Biology, Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912, USA; Hassenfeld Child Health Innovation Institute of Brown University, Providence, RI 02912, USA.
| | - Nima Mosammaparast
- Department of Pathology & Immunology, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA.
| |
Collapse
|
184
|
Liu Y, Yao Z, Lian G, Yang P. Biomolecular phase separation in stress granule assembly and virus infection. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1099-1118. [PMID: 37401177 PMCID: PMC10415189 DOI: 10.3724/abbs.2023117] [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: 12/28/2022] [Accepted: 05/06/2023] [Indexed: 07/05/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) has emerged as a crucial mechanism for cellular compartmentalization. One prominent example of this is the stress granule. Found in various types of cells, stress granule is a biomolecular condensate formed through phase separation. It comprises numerous RNA and RNA-binding proteins. Over the past decades, substantial knowledge has been gained about the composition and dynamics of stress granules. SGs can regulate various signaling pathways and have been associated with numerous human diseases, such as neurodegenerative diseases, cancer, and infectious diseases. The threat of viral infections continues to loom over society. Both DNA and RNA viruses depend on host cells for replication. Intriguingly, many stages of the viral life cycle are closely tied to RNA metabolism in human cells. The field of biomolecular condensates has rapidly advanced in recent times. In this context, we aim to summarize research on stress granules and their link to viral infections. Notably, stress granules triggered by viral infections behave differently from the canonical stress granules triggered by sodium arsenite (SA) and heat shock. Studying stress granules in the context of viral infections could offer a valuable platform to link viral replication processes and host anti-viral responses. A deeper understanding of these biological processes could pave the way for innovative interventions and treatments for viral infectious diseases. They could potentially bridge the gap between basic biological processes and interactions between viruses and their hosts.
Collapse
Affiliation(s)
- Yi Liu
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Zhiying Yao
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Guiwei Lian
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Peiguo Yang
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| |
Collapse
|
185
|
Hurtle BT, Xie L, Donnelly CJ. Disrupting pathologic phase transitions in neurodegeneration. J Clin Invest 2023; 133:e168549. [PMID: 37395272 DOI: 10.1172/jci168549] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023] Open
Abstract
Solid-like protein deposits found in aged and diseased human brains have revealed a relationship between insoluble protein accumulations and the resulting deficits in neurologic function. Clinically diverse neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, frontotemporal lobar degeneration, and amyotrophic lateral sclerosis, exhibit unique and disease-specific biochemical protein signatures and abnormal protein depositions that often correlate with disease pathogenesis. Recent evidence indicates that many pathologic proteins assemble into liquid-like protein phases through the highly coordinated process of liquid-liquid phase separation. Over the last decade, biomolecular phase transitions have emerged as a fundamental mechanism of cellular organization. Liquid-like condensates organize functionally related biomolecules within the cell, and many neuropathology-associated proteins reside within these dynamic structures. Thus, examining biomolecular phase transitions enhances our understanding of the molecular mechanisms mediating toxicity across diverse neurodegenerative diseases. This Review explores the known mechanisms contributing to aberrant protein phase transitions in neurodegenerative diseases, focusing on tau and TDP-43 proteinopathies and outlining potential therapeutic strategies to regulate these pathologic events.
Collapse
Affiliation(s)
- Bryan T Hurtle
- Center for Neuroscience at the University of Pittsburgh Graduate Program
- Medical Scientist Training Program, University of Pittsburgh; and
- LiveLikeLou Center for ALS Research at the University of Pittsburgh Brain Institute; Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Longxin Xie
- LiveLikeLou Center for ALS Research at the University of Pittsburgh Brain Institute; Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- School of Medicine, Tsinghua University, Beijing, China
| | - Christopher J Donnelly
- Center for Neuroscience at the University of Pittsburgh Graduate Program
- Medical Scientist Training Program, University of Pittsburgh; and
- LiveLikeLou Center for ALS Research at the University of Pittsburgh Brain Institute; Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
186
|
Chauhan G, Bremer A, Dar F, Mittag T, Pappu RV. Crowder titrations enable the quantification of driving forces for macromolecular phase separation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.03.547544. [PMID: 37461587 PMCID: PMC10350001 DOI: 10.1101/2023.07.03.547544] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Macromolecular solubility is an important contributor to the driving forces for phase separation. Formally, the driving forces in a binary mixture comprising a macromolecule dissolved in a solvent can be quantified in terms of the saturation concentration, which is the threshold macromolecular concentration above which the mixture separates into coexisting dense and dilute phases. Additionally, the second virial coefficient, which measures the effective strength of solvent-mediated intermolecular interactions provides direct assessments of solvent quality. The sign and magnitude of second virial coefficients will be governed by a combination of solution conditions and the nature of the macromolecule of interest. Here, we show, using a combination of theory, simulation, and in vitro experiments, that titrations of crowders, providing they are true depletants, can be used to extract the intrinsic driving forces for macromolecular phase separation. This refers to saturation concentrations in the absence of crowders and the second virial coefficients that quantify the magnitude of the incompatibility between macromolecules and the solvent. Our results show how the depletion-mediated attractions afforded by crowders can be leveraged to obtain comparative assessments of macromolecule-specific, intrinsic driving forces for phase separation. SIGNIFICANCE Phase separation has emerged as a process of significant relevance to sorting macromolecules into distinct compartments, thereby enabling spatial and temporal control over cellular matter. Considerable effort is being invested into uncovering the driving forces that enable the separation of macromolecular solutions into coexisting phases. At its heart, this process is governed by the balance of macromolecule-solvent, inter-macromolecule, and solvent-solvent interactions. We show that the driving forces for phase separation, including the coefficients that measure interaction strengths between macromolecules, can be extracted by titrating the concentrations of crowders that enable macromolecules to phase separate at lower concentrations. Our work paves the way to leverage specific categories of measurements for quantitative characterizations of driving forces for phase separation.
Collapse
|
187
|
Sarthak K, Winogradoff D, Ge Y, Myong S, Aksimentiev A. Benchmarking Molecular Dynamics Force Fields for All-Atom Simulations of Biological Condensates. J Chem Theory Comput 2023; 19:3721-3740. [PMID: 37134270 PMCID: PMC11169342 DOI: 10.1021/acs.jctc.3c00148] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Proteins containing intrinsically disordered regions are integral parts of the cellular signaling pathways and common components of biological condensates. Point mutations in the protein sequence, genetic at birth or acquired through aging, can alter the properties of the condensates, marking the onset of neurodegenerative diseases such as ALS and dementia. While the all-atom molecular dynamics method can, in principle, elucidate the conformational changes that arise from point mutations, the applications of this method to protein condensate systems is conditioned upon the availability of molecular force fields that can accurately describe both structured and disordered regions of such proteins. Using the special-purpose Anton 2 supercomputer, we benchmarked the efficacy of nine presently available molecular force fields in describing the structure and dynamics of a Fused in sarcoma (FUS) protein. Five-microsecond simulations of the full-length FUS protein characterized the effect of the force field on the global conformation of the protein, self-interactions among its side chains, solvent accessible surface area, and the diffusion constant. Using the results of dynamic light scattering as a benchmark for the FUS radius of gyration, we identified several force fields that produced FUS conformations within the experimental range. Next, we used these force fields to perform ten-microsecond simulations of two structured RNA binding domains of FUS bound to their respective RNA targets, finding the choice of the force field to affect stability of the RNA-FUS complex. Taken together, our data suggest that a combination of protein and RNA force fields sharing a common four-point water model provides an optimal description of proteins containing both disordered and structured regions and RNA-protein interactions. To make simulations of such systems available beyond the Anton 2 machines, we describe and validate implementation of the best performing force fields in a publicly available molecular dynamics program NAMD. Our NAMD implementation enables simulations of large (tens of millions of atoms) biological condensate systems and makes such simulations accessible to a broader scientific community.
Collapse
Affiliation(s)
- Kumar Sarthak
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
| | - David Winogradoff
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
| | - Yingda Ge
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Sua Myong
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Aleksei Aksimentiev
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois 61820, United States
| |
Collapse
|
188
|
Joo J, Cho S, Hong S, Min S, Kim K, Kumar R, Choi JM, Shin Y, Jung I. Probabilistic establishment of speckle-associated inter-chromosomal interactions. Nucleic Acids Res 2023; 51:5377-5395. [PMID: 37013988 PMCID: PMC10287923 DOI: 10.1093/nar/gkad211] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 03/08/2023] [Accepted: 03/25/2023] [Indexed: 04/05/2023] Open
Abstract
Inter-chromosomal interactions play a crucial role in genome organization, yet the organizational principles remain elusive. Here, we introduce a novel computational method to systematically characterize inter-chromosomal interactions using in situ Hi-C results from various cell types. Our method successfully identifies two apparently hub-like inter-chromosomal contacts associated with nuclear speckles and nucleoli, respectively. Interestingly, we discover that nuclear speckle-associated inter-chromosomal interactions are highly cell-type invariant with a marked enrichment of cell-type common super-enhancers (CSEs). Validation using DNA Oligopaint fluorescence in situ hybridization (FISH) shows a strong but probabilistic interaction behavior between nuclear speckles and CSE-harboring genomic regions. Strikingly, we find that the likelihood of speckle-CSE associations can accurately predict two experimentally measured inter-chromosomal contacts from Hi-C and Oligopaint DNA FISH. Our probabilistic establishment model well describes the hub-like structure observed at the population level as a cumulative effect of summing individual stochastic chromatin-speckle interactions. Lastly, we observe that CSEs are highly co-occupied by MAZ binding and MAZ depletion leads to significant disorganization of speckle-associated inter-chromosomal contacts. Taken together, our results propose a simple organizational principle of inter-chromosomal interactions mediated by MAZ-occupied CSEs.
Collapse
Affiliation(s)
- Jaegeon Joo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Sunghyun Cho
- Department of Mechanical Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Sukbum Hong
- Department of Mechanical Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Sunwoo Min
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Kyukwang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Rajeev Kumar
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
| | - Jeong-Mo Choi
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Republic of Korea
| | - Yongdae Shin
- Department of Mechanical Engineering, Seoul National University, Seoul 08826, Republic of Korea
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Inkyung Jung
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| |
Collapse
|
189
|
Guo C, Alfaro-Aco R, Zhang C, Russell RW, Petry S, Polenova T. Structural basis of protein condensation on microtubules underlying branching microtubule nucleation. Nat Commun 2023; 14:3682. [PMID: 37344496 PMCID: PMC10284871 DOI: 10.1038/s41467-023-39176-z] [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: 09/13/2022] [Accepted: 06/01/2023] [Indexed: 06/23/2023] Open
Abstract
Targeting protein for Xklp2 (TPX2) is a key factor that stimulates branching microtubule nucleation during cell division. Upon binding to microtubules (MTs), TPX2 forms condensates via liquid-liquid phase separation, which facilitates recruitment of microtubule nucleation factors and tubulin. We report the structure of the TPX2 C-terminal minimal active domain (TPX2α5-α7) on the microtubule lattice determined by magic-angle-spinning NMR. We demonstrate that TPX2α5-α7 forms a co-condensate with soluble tubulin on microtubules and binds to MTs between two adjacent protofilaments and at the intersection of four tubulin heterodimers. These interactions stabilize the microtubules and promote the recruitment of tubulin. Our results reveal that TPX2α5-α7 is disordered in solution and adopts a folded structure on MTs, indicating that TPX2α5-α7 undergoes structural changes from unfolded to folded states upon binding to microtubules. The aromatic residues form dense interactions in the core, which stabilize folding of TPX2α5-α7 on microtubules. This work informs on how the phase-separated TPX2α5-α7 behaves on microtubules and represents an atomic-level structural characterization of a protein that is involved in a condensate on cytoskeletal filaments.
Collapse
Affiliation(s)
- Changmiao Guo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Raymundo Alfaro-Aco
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Chunting Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Ryan W Russell
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| |
Collapse
|
190
|
Huang Y, Huang X. Biomolecule-Based Coacervates with Modulated Physiological Functions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37339359 DOI: 10.1021/acs.langmuir.3c00628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Liquid-liquid phase separation (LLPS) exists widely in living systems, and understanding the working mechanisms of the formed condensed droplets is of great significance for the prevention and treatment of diseases as well as for the development of biomimetic materials. Herein, in this Perspective we try to focus on the in vitro reconstructions of biomolecule-based coacervates and outline the associations between the functional components and droplets as well as the physiological and pathological functions associated with coacervates. Coacervates are formed by functional components through weak, multivalent interactions. The interaction strengths that determine coacervate properties such as electability and phase state, which in turn influence the functional components to limit their fluidity, stability, or diffusion coefficients, are specially discussed. At the end of this Perspective, the current challenges are summarized; progress will require our great efforts to reveal the mechanisms of action at the molecular level and then develop biomolecule-based coacervate models with complexity, integration of methods, and intellectualization.
Collapse
Affiliation(s)
- Yan Huang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Xin Huang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| |
Collapse
|
191
|
Farag M, Holehouse AS, Zeng X, Pappu RV. FIREBALL: A tool to fit protein phase diagrams based on mean-field theories for polymer solutions. Biophys J 2023; 122:2396-2403. [PMID: 37161095 PMCID: PMC10323018 DOI: 10.1016/j.bpj.2023.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 04/26/2023] [Accepted: 05/05/2023] [Indexed: 05/11/2023] Open
Abstract
Biomolecular condensates form via phase transitions of condensate-specific biomacromolecules. Intrinsically disordered regions featuring the appropriate sequence grammars can contribute via homotypic and heterotypic interactions to the driving forces for phase separation of multivalent proteins. Experiments and computations have matured to the point where the concentrations of coexisting dense and dilute phases can be measured or computed for individual intrinsically disordered regions in complex milieus. For a macromolecule such as a disordered protein in a solvent, the locus of points that connects concentrations of the two coexisting phases defines a phase boundary, or binodal. Often, only a few points along the binodal are accessible via measurements. In such cases, and for quantitative and comparative analysis of parameters that describe the driving forces for phase separation, it is useful to fit measured or computed binodals to mean-field free energies for polymer solutions. The nonlinearity of the underlying free energy functions makes it challenging to put mean-field theories into practice. Here, we present FIREBALL, a suite of computational tools designed to enable efficient construction, analysis, and fitting to experimental or computed data of binodals. We show that depending on the theory being used, one can also extract information regarding coil-to-globule transitions of individual macromolecules.
Collapse
Affiliation(s)
- Mina Farag
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri; Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, Missouri
| | - Alex S Holehouse
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, Missouri; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri
| | - Xiangze Zeng
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong; Teaching and Research Division, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Rohit V Pappu
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri; Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, Missouri.
| |
Collapse
|
192
|
Jonas F, Carmi M, Krupkin B, Steinberger J, Brodsky S, Jana T, Barkai N. The molecular grammar of protein disorder guiding genome-binding locations. Nucleic Acids Res 2023; 51:4831-4844. [PMID: 36938874 PMCID: PMC10250222 DOI: 10.1093/nar/gkad184] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 01/25/2023] [Accepted: 03/15/2023] [Indexed: 03/21/2023] Open
Abstract
Intrinsically disordered regions (IDRs) direct transcription factors (TFs) towards selected genomic occurrences of their binding motif, as exemplified by budding yeast's Msn2. However, the sequence basis of IDR-directed TF binding selectivity remains unknown. To reveal this sequence grammar, we analyze the genomic localizations of >100 designed IDR mutants, each carrying up to 122 mutations within this 567-AA region. Our data points at multivalent interactions, carried by hydrophobic-mostly aliphatic-residues dispersed within a disordered environment and independent of linear sequence motifs, as the key determinants of Msn2 genomic localization. The implications of our results for the mechanistic basis of IDR-based TF binding preferences are discussed.
Collapse
Affiliation(s)
- Felix Jonas
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miri Carmi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Beniamin Krupkin
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Joseph Steinberger
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tamar Jana
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| |
Collapse
|
193
|
Abstract
Biomolecular condensates constitute a newly recognized form of spatial organization in living cells. Although many condensates are believed to form as a result of phase separation, the physicochemical properties that determine the phase behavior of heterogeneous biomolecular mixtures are only beginning to be explored. Theory and simulation provide invaluable tools for probing the relationship between molecular determinants, such as protein and RNA sequences, and the emergence of phase-separated condensates in such complex environments. This review covers recent advances in the prediction and computational design of biomolecular mixtures that phase-separate into many coexisting phases. First, we review efforts to understand the phase behavior of mixtures with hundreds or thousands of species using theoretical models and statistical approaches. We then describe progress in developing analytical theories and coarse-grained simulation models to predict multiphase condensates with the molecular detail required to make contact with biophysical experiments. We conclude by summarizing the challenges ahead for modeling the inhomogeneous spatial organization of biomolecular mixtures in living cells.
Collapse
Affiliation(s)
- William M Jacobs
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| |
Collapse
|
194
|
Thirumalai D, Kumar A, Chakraborty D, Straub JE, Mugnai ML. Conformational Fluctuations and Phases in Fused in Sarcoma (FUS) Low-Complexity Domain. ARXIV 2023:arXiv:2303.04215v2. [PMID: 36945688 PMCID: PMC10029050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The well known phenomenon of phase separation in synthetic polymers and proteins has become a major topic in biophysics because it has been invoked as a mechanism of compartment formation in cells, without the need for membranes. Most of the coacervates (or condensates) are composed of Intrinsically Disordered Proteins (IDPs) or regions that are structureless, often in interaction with RNA and DNA. One of the more intriguing IDPs is the 526-residue RNA binding protein, Fused In Sarcoma (FUS), whose monomer conformations and condensates exhibit unusual behavior that are sensitive to solution conditions. By focussing principally on the N-terminus low complexity domain (FUS-LC comprising residues 1-214) and other truncations, we rationalize the findings of solid state NMR experiments, which show that FUS-LC adopts a non-polymorphic fibril (core-1) involving residues 39-95, flanked by fuzzy coats on both the N- and C- terminal ends. An alternate structure (core-2), whose free energy is comparable to core-1, emerges only in the truncated construct (residues 110-214). Both core-1 and core-2 fibrils are stabilized by a Tyrosine ladder as well as hydrophilic interactions. The morphologies (gels, fibrils, and glass-like behavior) adopted by FUS seem to vary greatly, depending on the experimental conditions. The effect of phosphorylation is site specific and affects the stability of the fibril depending on the sites that are phosphorylated. Many of the peculiarities associated with FUS may also be shared by other IDPs, such as TDP43 and hnRNPA2. We outline a number of problems for which there is no clear molecular understanding.
Collapse
Affiliation(s)
- D Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
- Department of Physics, The University of Texas at Austin, Austin, TX 78712
| | - Abhinaw Kumar
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - Debayan Chakraborty
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - John E Straub
- Department of Chemistry, Boston University, Boston, MA 78712
| | - Mauro L Mugnai
- Institute of Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057
| |
Collapse
|
195
|
Alston JJ, Ginell GM, Soranno A, Holehouse AS. The Analytical Flory Random Coil Is a Simple-to-Use Reference Model for Unfolded and Disordered Proteins. J Phys Chem B 2023; 127:4746-4760. [PMID: 37200094 PMCID: PMC10875986 DOI: 10.1021/acs.jpcb.3c01619] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Denatured, unfolded, and intrinsically disordered proteins (collectively referred to here as unfolded proteins) can be described using analytical polymer models. These models capture various polymeric properties and can be fit to simulation results or experimental data. However, the model parameters commonly require users' decisions, making them useful for data interpretation but less clearly applicable as stand-alone reference models. Here we use all-atom simulations of polypeptides in conjunction with polymer scaling theory to parameterize an analytical model of unfolded polypeptides that behave as ideal chains (ν = 0.50). The model, which we call the analytical Flory random coil (AFRC), requires only the amino acid sequence as input and provides direct access to probability distributions of global and local conformational order parameters. The model defines a specific reference state to which experimental and computational results can be compared and normalized. As a proof-of-concept, we use the AFRC to identify sequence-specific intramolecular interactions in simulations of disordered proteins. We also use the AFRC to contextualize a curated set of 145 different radii of gyration obtained from previously published small-angle X-ray scattering experiments of disordered proteins. The AFRC is implemented as a stand-alone software package and is also available via a Google Colab notebook. In summary, the AFRC provides a simple-to-use reference polymer model that can guide intuition and aid in interpreting experimental or simulation results.
Collapse
Affiliation(s)
- Jhullian J. Alston
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, USA
| | - Garrett M. Ginell
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, USA
| | - Alex S. Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St. Louis, St. Louis, MO, USA
| |
Collapse
|
196
|
Vendruscolo M, Fuxreiter M. Towards sequence-based principles for protein phase separation predictions. Curr Opin Chem Biol 2023; 75:102317. [PMID: 37207400 DOI: 10.1016/j.cbpa.2023.102317] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/07/2023] [Accepted: 04/11/2023] [Indexed: 05/21/2023]
Abstract
The phenomenon of protein phase separation, which underlies the formation of biomolecular condensates, has been associated with numerous cellular functions. Recent studies indicate that the amino acid sequences of most proteins may harbour not only the code for folding into the native state but also for condensing into the liquid-like droplet state and the solid-like amyloid state. Here we review the current understanding of the principles for sequence-based methods for predicting the propensity of proteins for phase separation. A guiding concept is that entropic contributions are generally more important to stabilise the droplet state than they are for the native and amyloid states. Although estimating these entropic contributions has proven difficult, we describe some progress that has been recently made in this direction. To conclude, we discuss the challenges ahead to extend sequence-based prediction methods of protein phase separation to include quantitative in vivo characterisations of this process.
Collapse
Affiliation(s)
- Michele Vendruscolo
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.
| | - Monika Fuxreiter
- Department of Biomedical Sciences, University of Padova, PD 35131, Italy; Department of Physics and Astronomy, University of Padova, PD 35131, Italy.
| |
Collapse
|
197
|
Guseva S, Schnapka V, Adamski W, Maurin D, Ruigrok RWH, Salvi N, Blackledge M. Liquid-Liquid Phase Separation Modifies the Dynamic Properties of Intrinsically Disordered Proteins. J Am Chem Soc 2023; 145:10548-10563. [PMID: 37146977 DOI: 10.1021/jacs.2c13647] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Liquid-liquid phase separation of flexible biomolecules has been identified as a ubiquitous phenomenon underlying the formation of membraneless organelles that harbor a multitude of essential cellular processes. We use nuclear magnetic resonance (NMR) spectroscopy to compare the dynamic properties of an intrinsically disordered protein (measles virus NTAIL) in the dilute and dense phases at atomic resolution. By measuring 15N NMR relaxation at different magnetic field strengths, we are able to characterize the dynamics of the protein in dilute and crowded conditions and to compare the amplitude and timescale of the different motional modes to those present in the membraneless organelle. Although the local backbone conformational sampling appears to be largely retained, dynamics occurring on all detectable timescales, including librational, backbone dihedral angle dynamics and segmental, chainlike motions, are considerably slowed down. Their relative amplitudes are also drastically modified, with slower, chain-like motions dominating the dynamic profile. In order to provide additional mechanistic insight, we performed extensive molecular dynamics simulations of the protein under self-crowding conditions at concentrations comparable to those found in the dense liquid phase. Simulation broadly reproduces the impact of formation of the condensed phase on both the free energy landscape and the kinetic interconversion between states. In particular, the experimentally observed reduction in the amplitude of the fastest component of backbone dynamics correlates with higher levels of intermolecular contacts or entanglement observed in simulations, reducing the conformational space available to this mode under strongly self-crowding conditions.
Collapse
Affiliation(s)
- Serafima Guseva
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - Vincent Schnapka
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - Wiktor Adamski
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - Damien Maurin
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - Rob W H Ruigrok
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - Nicola Salvi
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| | - Martin Blackledge
- Institut de Biologie Structurale, Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38000 Grenoble, France
| |
Collapse
|
198
|
Pappu R, Farag M, Borcherds W, Bremer A, Mittag T. Phase Separation in Mixtures of Prion-Like Low Complexity Domains is Driven by the Interplay of Homotypic and Heterotypic Interactions. RESEARCH SQUARE 2023:rs.3.rs-2870258. [PMID: 37205474 PMCID: PMC10187436 DOI: 10.21203/rs.3.rs-2870258/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Prion-like low-complexity domains (PLCDs) are involved in the formation and regulation of distinct biomolecular condensates that form via coupled associative and segregative phase transitions. We previously deciphered how evolutionarily conserved sequence features drive phase separation of PLCDs through homotypic interactions. However, condensates typically encompass a diverse mixture of proteins with PLCDs. Here, we combine simulations and experiments to study mixtures of PLCDs from two RNA binding proteins namely, hnRNPA1 and FUS. We find that 1:1 mixtures of the A1-LCD and FUS-LCD undergo phase separation more readily than either of the PLCDs on their own. The enhanced driving forces for phase separation of mixtures of A1-LCD and FUS-LCD arise partly from complementary electrostatic interactions between the two proteins. This complex coacervation-like mechanism adds to complementary interactions among aromatic residues. Further, tie line analysis shows that stoichiometric ratios of different components and their sequence-encoded interactions jointly contribute to the driving forces for condensate formation. These results highlight how expression levels might be tuned to regulate the driving forces for condensate formation in vivo . Simulations also show that the organization of PLCDs within condensates deviates from expectations based on random mixture models. Instead, spatial organization within condensates will reflect the relative strengths of homotypic versus heterotypic interactions. We also uncover rules for how interaction strengths and sequence lengths modulate conformational preferences of molecules at interfaces of condensates formed by mixtures of proteins. Overall, our findings emphasize the network-like organization of molecules within multicomponent condensates, and the distinctive, composition-specific conformational features of condensate interfaces.
Collapse
|
199
|
Rekhi S, Sundaravadivelu Devarajan D, Howard MP, Kim YC, Nikoubashman A, Mittal J. Role of Strong Localized vs Weak Distributed Interactions in Disordered Protein Phase Separation. J Phys Chem B 2023; 127:3829-3838. [PMID: 37079924 PMCID: PMC10187732 DOI: 10.1021/acs.jpcb.3c00830] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/03/2023] [Indexed: 04/22/2023]
Abstract
Interaction strength and localization are critical parameters controlling the single-chain and condensed-state properties of intrinsically disordered proteins (IDPs). Here, we decipher these relationships using coarse-grained heteropolymers comprised of hydrophobic (H) and polar (P) monomers as model IDPs. We systematically vary the fraction of P monomers XP and employ two distinct particle-based models that include either strong localized attractions between only H-H pairs (HP model) or weak distributed attractions between both H-H and H-P pairs (HP+ model). To compare different sequences and models, we first carefully tune the attraction strength for all sequences to match the single-chain radius of gyration. Interestingly, we find that this procedure produces similar conformational ensembles, nonbonded potential energies, and chain-level dynamics for single chains of almost all sequences in both models, with some deviations for the HP model at large XP. However, we observe a surprisingly rich phase behavior for the sequences in both models that deviates from the expectation that similarity at the single-chain level will translate to a similar phase-separation propensity. Coexistence between dilute and dense phases is only observed up to a model-dependent XP, despite the presence of favorable interchain interactions, which we quantify using the second virial coefficient. Instead, the limited number of attractive sites (H monomers) leads to the self-assembly of finite-sized clusters of different sizes depending on XP. Our findings strongly suggest that models with distributed interactions favor the formation of liquid-like condensates over a much larger range of sequence compositions compared to models with localized interactions.
Collapse
Affiliation(s)
- Shiv Rekhi
- Artie
McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | | | - Michael P. Howard
- Department
of Chemical Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Young C. Kim
- Center
for Materials Physics and Technology, Naval
Research Laboratory, Washington, D.C. 20375, United States
| | - Arash Nikoubashman
- Institute
of Physics, Johannes Gutenberg University
Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - Jeetain Mittal
- Artie
McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Interdisciplinary
Graduate Program in Genetics and Genomics, Texas A&M University, College
Station, Texas 77843, United States
| |
Collapse
|
200
|
Ravindran R, Bacellar IOL, Castellanos-Girouard X, Wahba HM, Zhang Z, Omichinski JG, Kisley L, Michnick SW. Peroxisome biogenesis initiated by protein phase separation. Nature 2023; 617:608-615. [PMID: 37165185 PMCID: PMC10302873 DOI: 10.1038/s41586-023-06044-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 04/03/2023] [Indexed: 05/12/2023]
Abstract
Peroxisomes are organelles that carry out β-oxidation of fatty acids and amino acids. Both rare and prevalent diseases are caused by their dysfunction1. Among disease-causing variant genes are those required for protein transport into peroxisomes. The peroxisomal protein import machinery, which also shares similarities with chloroplasts2, is unique in transporting folded and large, up to 10 nm in diameter, protein complexes into peroxisomes3. Current models postulate a large pore formed by transmembrane proteins4; however, so far, no pore structure has been observed. In the budding yeast Saccharomyces cerevisiae, the minimum transport machinery includes the membrane proteins Pex13 and Pex14 and the cargo-protein-binding transport receptor, Pex5. Here we show that Pex13 undergoes liquid-liquid phase separation (LLPS) with Pex5-cargo. Intrinsically disordered regions in Pex13 and Pex5 resemble those found in nuclear pore complex proteins. Peroxisomal protein import depends on both the number and pattern of aromatic residues in these intrinsically disordered regions, consistent with their roles as 'stickers' in associative polymer models of LLPS5,6. Finally, imaging fluorescence cross-correlation spectroscopy shows that cargo import correlates with transient focusing of GFP-Pex13 and GFP-Pex14 on the peroxisome membrane. Pex13 and Pex14 form foci in distinct time frames, suggesting that they may form channels at different saturating concentrations of Pex5-cargo. Our findings lead us to suggest a model in which LLPS of Pex5-cargo with Pex13 and Pex14 results in transient protein transport channels7.
Collapse
Affiliation(s)
- Rini Ravindran
- Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada
| | - Isabel O L Bacellar
- Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada
- Douglas Research Centre, Montreal, Quebec, Canada
| | | | - Haytham M Wahba
- Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada
- Department of Biochemistry, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
| | - Zhenghao Zhang
- Department of Physics, Case Western Reserve University, Cleveland, OH, USA
- Mitchell Physics Building (MPHY), College Station, TX, USA
| | - James G Omichinski
- Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada
| | - Lydia Kisley
- Department of Physics, Case Western Reserve University, Cleveland, OH, USA
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, USA
| | - Stephen W Michnick
- Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada.
| |
Collapse
|