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Gibbs EB, Miao Q, Perrone B, Hassan A, Kümmerle R, Kriwacki R. Investigating the molecular basis of ARF tumor suppressor function in the nucleolus: how ARF disrupts ribosome biogenesis and function. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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Mitrea DM, Chandra B, Ferrolino MC, Gibbs EB, Tolbert M, White MR, Kriwacki RW. Methods for Physical Characterization of Phase-Separated Bodies and Membrane-less Organelles. J Mol Biol 2018; 430:4773-4805. [PMID: 30017918 PMCID: PMC6503534 DOI: 10.1016/j.jmb.2018.07.006] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/04/2018] [Accepted: 07/09/2018] [Indexed: 12/17/2022]
Abstract
Membrane-less organelles are cellular structures which arise through the phenomenon of phase separation. This process enables compartmentalization of specific sets of macromolecules (e.g., proteins, nucleic acids), thereby regulating cellular processes by increasing local concentration, and modulating the structure and dynamics of their constituents. Understanding the connection between structure, material properties and function of membrane-less organelles requires inter-disciplinary approaches, which address length and timescales that span several orders of magnitude (e.g., Ångstroms to micrometer, picoseconds to hours). In this review, we discuss the wide variety of methods that have been applied to characterize the morphology, rheology, structure and dynamics of membrane-less organelles and their components, in vitro and in live cells.
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Affiliation(s)
- Diana M Mitrea
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Bappaditya Chandra
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Mylene C Ferrolino
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Eric B Gibbs
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Michele Tolbert
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Michael R White
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Richard W Kriwacki
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA.
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Gibbs EB, Laremore TN, Usher GA, Portz B, Cook EC, Showalter SA. Substrate Specificity of the Kinase P-TEFb towards the RNA Polymerase II C-Terminal Domain. Biophys J 2017; 113:1909-1911. [DOI: 10.1016/j.bpj.2017.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/24/2017] [Accepted: 09/11/2017] [Indexed: 10/18/2022] Open
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Gibbs EB, Lu F, Portz B, Fisher MJ, Medellin BP, Laremore TN, Zhang YJ, Gilmour DS, Showalter SA. Phosphorylation induces sequence-specific conformational switches in the RNA polymerase II C-terminal domain. Nat Commun 2017; 8:15233. [PMID: 28497798 PMCID: PMC5437310 DOI: 10.1038/ncomms15233] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/09/2017] [Indexed: 01/25/2023] Open
Abstract
The carboxy-terminal domain (CTD) of the RNA polymerase II (Pol II) large subunit cycles through phosphorylation states that correlate with progression through the transcription cycle and regulate nascent mRNA processing. Structural analyses of yeast and mammalian CTD are hampered by their repetitive sequences. Here we identify a region of the Drosophila melanogaster CTD that is essential for Pol II function in vivo and capitalize on natural sequence variations within it to facilitate structural analysis. Mass spectrometry and NMR spectroscopy reveal that hyper-Ser5 phosphorylation transforms the local structure of this region via proline isomerization. The sequence context of this switch tunes the activity of the phosphatase Ssu72, leading to the preferential de-phosphorylation of specific heptads. Together, context-dependent conformational switches and biased dephosphorylation suggest a mechanism for the selective recruitment of cis-proline-specific regulatory factors and region-specific modulation of the CTD code that may augment gene regulation in developmentally complex organisms.
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Affiliation(s)
- Eric B Gibbs
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Feiyue Lu
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Bede Portz
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Michael J Fisher
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Brenda P Medellin
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Tatiana N Laremore
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - David S Gilmour
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Scott A Showalter
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.,Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Portz B, Lu F, Gibbs EB, Mayfield JE, Rachel Mehaffey M, Zhang YJ, Brodbelt JS, Showalter SA, Gilmour DS. Structural heterogeneity in the intrinsically disordered RNA polymerase II C-terminal domain. Nat Commun 2017; 8:15231. [PMID: 28497792 PMCID: PMC5437306 DOI: 10.1038/ncomms15231] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 03/09/2017] [Indexed: 11/09/2022] Open
Abstract
RNA polymerase II contains a repetitive, intrinsically disordered, C-terminal domain (CTD) composed of heptads of the consensus sequence YSPTSPS. The CTD is heavily phosphorylated and serves as a scaffold, interacting with factors involved in transcription initiation, elongation and termination, RNA processing and chromatin modification. Despite being a nexus of eukaryotic gene regulation, the structure of the CTD and the structural implications of phosphorylation are poorly understood. Here we present a biophysical and biochemical interrogation of the structure of the full length CTD of Drosophila melanogaster, which we conclude is a compact random coil. Surprisingly, we find that the repetitive CTD is structurally heterogeneous. Phosphorylation causes increases in radius, protein accessibility and stiffness, without disrupting local structural heterogeneity. Additionally, we show the human CTD is also structurally heterogeneous and able to substitute for the D. melanogaster CTD in supporting fly development to adulthood. This finding implicates conserved structural organization, not a precise array of heptad motifs, as important to CTD function.
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Affiliation(s)
- Bede Portz
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Feiyue Lu
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.,The Huck Institutes of Life Sciences. The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Eric B Gibbs
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Joshua E Mayfield
- Department of Molecular Biosciences, University of Texas, Austin, Texas 78712, USA
| | - M Rachel Mehaffey
- Department of Chemistry, University of Texas, Austin, Texas 78712, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, University of Texas, Austin, Texas 78712, USA.,Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA
| | | | - Scott A Showalter
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.,Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - David S Gilmour
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
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Gibbs EB, Cook EC, Showalter SA. Application of NMR to studies of intrinsically disordered proteins. Arch Biochem Biophys 2017; 628:57-70. [PMID: 28502465 DOI: 10.1016/j.abb.2017.05.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 05/08/2017] [Accepted: 05/10/2017] [Indexed: 12/20/2022]
Abstract
The prevalence of intrinsically disordered protein regions, particularly in eukaryotic proteins, and their clear functional advantages for signaling and gene regulation have created an imperative for high-resolution structural and mechanistic studies. NMR spectroscopy has played a central role in enhancing not only our understanding of the intrinsically disordered native state, but also how that state contributes to biological function. While pathological functions associated with protein aggregation are well established, it has recently become clear that disordered regions also mediate functionally advantageous assembly into high-order structures that promote the formation of membrane-less sub-cellular compartments and even hydrogels. Across the range of functional assembly states accessed by disordered regions, post-translational modifications and regulatory macromolecular interactions, which can also be investigated by NMR spectroscopy, feature prominently. Here we will explore the many ways in which NMR has advanced our understanding of the physical-chemical phase space occupied by disordered protein regions and provide prospectus for the future role of NMR in this emerging and exciting field.
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Affiliation(s)
- Eric B Gibbs
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Erik C Cook
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Scott A Showalter
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA; Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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Gibbs EB, Showalter SA. Quantification of Compactness and Local Order in the Ensemble of the Intrinsically Disordered Protein FCP1. J Phys Chem B 2016; 120:8960-9. [DOI: 10.1021/acs.jpcb.6b06934] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Eric B. Gibbs
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Scott A. Showalter
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Abstract
Intrinsically disordered proteins (IDPs) are broadly defined as protein regions that do not cooperatively fold into a spatially or temporally stable structure. Recent research strongly supports the hypothesis that a conserved functional role for structural disorder renders IDPs uniquely capable of functioning in biological processes such as cellular signaling and transcription. Recently, the frequency of application of rigorous mechanistic biochemistry and quantitative biophysics to disordered systems has increased dramatically. For example, the launch of the Protein Ensemble Database (pE-DB) demonstrates that the potential now exists to refine models for the native state structure of IDPs using experimental data. However, rigorous assessment of which observables place the strongest and least biased constraints on those ensembles is now needed. Most importantly, the past few years have seen strong growth in the number of biochemical and biophysical studies attempting to connect structural disorder with function. From the perspective of equilibrium thermodynamics, there is a clear need to assess the relative significance of hydrophobic versus electrostatic forces in IDP interactions, if it is possible to generalize at all. Finally, kinetic mechanisms that invoke conformational selection and/or induced fit are often used to characterize coupled IDP folding and binding, although application of these models is typically built upon thermodynamic observations. Recently, the reaction rates and kinetic mechanisms of more intrinsically disordered systems have been tested through rigorous kinetic experiments. Motivated by these exciting advances, here we provide a review and prospectus for the quantitative study of IDP structure, thermodynamics, and kinetics.
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Affiliation(s)
- Eric B Gibbs
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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