43
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      RNA-Induced Conformational Switching and Clustering of G3BP Drive Stress Granule Assembly by Condensation

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Summary

          Stressed cells shut down translation, release mRNA molecules from polysomes, and form stress granules (SGs) via a network of interactions that involve G3BP. Here we focus on the mechanistic underpinnings of SG assembly. We show that, under non-stress conditions, G3BP adopts a compact auto-inhibited state stabilized by electrostatic intramolecular interactions between the intrinsically disordered acidic tracts and the positively charged arginine-rich region. Upon release from polysomes, unfolded mRNAs outcompete G3BP auto-inhibitory interactions, engendering a conformational transition that facilitates clustering of G3BP through protein-RNA interactions. Subsequent physical crosslinking of G3BP clusters drives RNA molecules into networked RNA/protein condensates. We show that G3BP condensates impede RNA entanglement and recruit additional client proteins that promote SG maturation or induce a liquid-to-solid transition that may underlie disease. We propose that condensation coupled to conformational rearrangements and heterotypic multivalent interactions may be a general principle underlying RNP granule assembly.

          Graphical Abstract

          Highlights

          • Under non-stressed conditions, G3BP adopts a compact auto-inhibited state

          • Conformational expansion of G3BP increases the interaction valences

          • G3BP clusters crosslink RNA to assemble stress granules upon cellular stress

          • G3BP condensates prevent RNA entanglement

          Abstract

          Reconstitution of stress granule assembly reveals an autoinhibitory conformation of G3BP that is alleviated by RNA binding, demonstrating how this central node of the stress granule network phase-separates in response to rising cellular RNA concentrations.

          Related collections

          Most cited references63

          • Record: found
          • Abstract: not found
          • Article: not found

          Watersheds in digital spaces: an efficient algorithm based on immersion simulations

            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            G3BP1 Is a Tunable Switch that Triggers Phase Separation to Assemble Stress Granules

            The mechanisms underlying ribonucleoprotein (RNP) granule assembly, including the basis for establishing and maintaining RNP granules with distinct composition, are unknown. One prominent type of RNP granule is the stress granule (SG), a dynamic and reversible cytoplasmic assembly formed in eukaryotic cells in response to stress. Here, we show that SGs assemble through liquid-liquid phase separation (LLPS) arising from interactions distributed unevenly across a core protein-RNA interaction network. The central node of this network is G3BP1, which functions as a molecular switch that triggers RNA-dependent LLPS in response to a rise in intracellular free RNA concentrations. Moreover, we show that interplay between three distinct intrinsically disordered regions (IDRs) in G3BP1 regulates its intrinsic propensity for LLPS, and this is fine-tuned by phosphorylation within the IDRs. Further regulation of SG assembly arises through positive or negative cooperativity by extrinsic G3BP1-binding factors that strengthen or weaken, respectively, the core SG network.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              The pairwise energy content estimated from amino acid composition discriminates between folded and intrinsically unstructured proteins.

              The structural stability of a protein requires a large number of interresidue interactions. The energetic contribution of these can be approximated by low-resolution force fields extracted from known structures, based on observed amino acid pairing frequencies. The summation of such energies, however, cannot be carried out for proteins whose structure is not known or for intrinsically unstructured proteins. To overcome these limitations, we present a novel method for estimating the total pairwise interaction energy, based on a quadratic form in the amino acid composition of the protein. This approach is validated by the good correlation of the estimated and actual energies of proteins of known structure and by a clear separation of folded and disordered proteins in the energy space it defines. As the novel algorithm has not been trained on unstructured proteins, it substantiates the concept of protein disorder, i.e. that the inability to form a well-defined 3D structure is an intrinsic property of many proteins and protein domains. This property is encoded in their sequence, because their biased amino acid composition does not allow sufficient stabilizing interactions to form. By limiting the calculation to a predefined sequential neighborhood, the algorithm was turned into a position-specific scoring scheme that characterizes the tendency of a given amino acid to fall into an ordered or disordered region. This application we term IUPred and compare its performance with three generally accepted predictors, PONDR VL3H, DISOPRED2 and GlobPlot on a database of disordered proteins.
                Bookmark

                Author and article information

                Contributors
                Journal
                Cell
                Cell
                Cell
                Cell Press
                0092-8674
                1097-4172
                16 April 2020
                16 April 2020
                : 181
                : 2
                : 346-361.e17
                Affiliations
                [1 ]Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
                [2 ]Department of Biomedical Engineering and Center for Science and Engineering of Living Systems, Washington University in St. Louis, St. Louis, MO 63130, USA
                [3 ]Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
                [4 ]Center for Self-Assembly and Complexity, Institute for Basic Science, Pohang 37673, Republic of Korea
                [5 ]Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
                [6 ]Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
                [7 ]Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
                Author notes
                []Corresponding author simon.alberti@ 123456tu-dresden.de
                [8]

                These authors contributed equally

                [9]

                Present address: Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland

                [10]

                Lead Contact

                Article
                S0092-8674(20)30342-1
                10.1016/j.cell.2020.03.049
                7181197
                32302572
                077aa312-f6e2-4079-b918-cdc9178dad7b
                © 2020 The Author(s)

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

                History
                : 25 January 2019
                : 23 October 2019
                : 20 March 2020
                Categories
                Article

                Cell biology
                stress granules,rnp granules,g3bp,phase separation,liquid-to-solid transition,neurodegenerative disease,stress response

                Comments

                Comment on this article