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Abstract
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Thanks to recent
improvements in NMR spectrometer hardware and
pulse sequence design, modern 13C NMR has become a useful
tool for biomolecular applications. The complete assignment of a protein
can be accomplished by using 13C detected multinuclear
experiments and it can provide unique information relevant for the
study of a variety of different biomolecules including paramagnetic
proteins and intrinsically disordered proteins. A wide range of NMR
observables can be measured, concurring to the structural and dynamic
characterization of a protein in isolation, as part of a larger complex,
or even inside a living cell. We present the different properties
of 13C with respect to 1H, which provide the
rationale for the experiments developed and their application, the
technical aspects that need to be faced, and the many experimental
variants designed to address different cases. Application areas where
these experiments successfully complement proton NMR are also described.
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Affiliation(s)
- Isabella C Felli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Roberta Pierattelli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
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2
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Prieto VA, Namitz KEW, Showalter SA. Transient Electrostatic Interactions between Fcp1 and Rap74 Bias the Conformational Ensemble of the Complex with Minimal Impact on Binding Affinity. J Phys Chem B 2021; 125:10917-10927. [PMID: 34550709 DOI: 10.1021/acs.jpcb.1c05131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intrinsically disordered protein (IDP) sequences often contain a high proportion of charged residues in conjunction with their high degree of hydrophilicity and solvation. For high net charge IDPs, long-range electrostatic interactions are thought to play a role in modulating the strength or kinetics of protein-protein interactions. In this work, we examined intramolecular interactions mediated by charged regions of a model IDP, the C-terminal tail of the phosphatase Fcp1. Specifically, this work focuses on intermolecular interactions between acidic and basic patches in the primary structure of Fcp1 and their contributions to binding its predominantly basic partner, the winged helix domain of Rap74. We observe both intramolecular and intermolecular interactions through paramagnetic relaxation enhancement (PRE) consistent with oppositely charged regions associating with one another, both in unbound Fcp1 and in the Fcp1-Rap74 complex. Formation of this complex is strongly driven by hydrophobic interactions in the minimal binding motif. Here, we test the hypothesis that charged residues in Fcp1 that flank the binding helix also contribute to the strength of binding. Charge inversion mutations in Fcp1 generally support this hypothesis, while PRE data suggest substitution of observed transient interactions in the unbound ensemble for similarly transient interactions with Rap74 in the complex.
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Affiliation(s)
- Victor A Prieto
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Kevin E W Namitz
- 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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3
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Lin X, Zhan H, Li H, Huang Y, Chen Z. NMR Relaxation Measurements on Complex Samples Based on Real-Time Pure Shift Techniques. Molecules 2020; 25:molecules25030473. [PMID: 31979172 PMCID: PMC7037015 DOI: 10.3390/molecules25030473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 01/15/2020] [Accepted: 01/19/2020] [Indexed: 11/16/2022] Open
Abstract
Longitudinal spin-lattice relaxation (T1) and transverse spin-spin relaxation (T2) reveal valuable information for studying molecular dynamics in NMR applications. Accurate relaxation measurements from conventional 1D proton spectra are generally subject to challenges of spectral congestion caused by J coupling splittings and spectral line broadenings due to magnetic field inhomogeneity. Here, we present an NMR relaxation method based on real-time pure shift techniques to overcome these two challenges and achieve accurate measurements of T1 and T2 relaxation times from complex samples that contain crowded NMR resonances even under inhomogeneous magnetic fields. Both theoretical analyses and detailed experiments are performed to demonstrate the effectiveness and ability of the proposed method for accurate relaxation measurements on complex samples and its practicability to non-ideal magnetic field conditions.
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Sicorello A, Kelly G, Oregioni A, Nováček J, Sklenář V, Pastore A. The Structural Properties in Solution of the Intrinsically Mixed Folded Protein Ataxin-3. Biophys J 2019; 115:59-71. [PMID: 29972812 DOI: 10.1016/j.bpj.2018.05.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 05/25/2018] [Accepted: 05/29/2018] [Indexed: 10/28/2022] Open
Abstract
It has increasingly become clear over the last two decades that proteins can contain both globular domains and intrinsically unfolded regions that can both contribute to function. Although equally interesting, the disordered regions are difficult to study, because they usually do not crystallize unless bound to partners and are not easily amenable to cryo-electron microscopy studies. NMR spectroscopy remains the best technique to capture the structural features of intrinsically mixed folded proteins and describe their dynamics. These studies rely on the successful assignment of the spectrum, a task not easy per se given the limited spread of the resonances of the disordered residues. Here, we describe the structural properties of ataxin-3, the protein responsible for the neurodegenerative Machado-Joseph disease. Ataxin-3 is a 42-kDa protein containing a globular N-terminal Josephin domain and a C-terminal tail that comprises 13 polyglutamine repeats within a low complexity region. We developed a strategy that allowed us to achieve 87% assignment of the NMR spectrum using a mixed protocol based on high-dimensionality, high-resolution experiments and different labeling schemes. Thanks to the almost complete spectral assignment, we proved that the C-terminal tail is flexible, with extended helical regions, and interacts only marginally with the rest of the protein. We could also, for the first time to our knowledge, observe the structural propensity of the polyglutamine repeats within the context of the full-length protein and show that its structure is stabilized by the preceding region.
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Affiliation(s)
- Alessandro Sicorello
- Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, United Kingdom
| | - Geoff Kelly
- Medical Research Council Biomolecular NMR Centre, The Francis Crick Institute, London, United Kingdom
| | - Alain Oregioni
- Medical Research Council Biomolecular NMR Centre, The Francis Crick Institute, London, United Kingdom
| | - Jiří Nováček
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Vladimír Sklenář
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Annalisa Pastore
- Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, United Kingdom; Department of Molecular Medicine, University of Pavia, Pavia, Italy.
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5
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Schiavina M, Murrali MG, Pontoriero L, Sainati V, Kümmerle R, Bermel W, Pierattelli R, Felli IC. Taking Simultaneous Snapshots of Intrinsically Disordered Proteins in Action. Biophys J 2019; 117:46-55. [PMID: 31176511 DOI: 10.1016/j.bpj.2019.05.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/03/2019] [Accepted: 05/14/2019] [Indexed: 12/20/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) as well as intrinsically disordered regions (IDRs) of complex protein machineries have recently been recognized as key players in many cellular functions. NMR represents a unique tool to access atomic resolution structural and dynamic information on highly flexible IDPs/IDRs. Improvements in instrumental sensitivity made heteronuclear direct detection possible for biomolecular NMR applications. The CON experiment has become one of the most useful NMR experiments to get a snapshot of an IDP/IDR in conditions approaching physiological ones. The availability of NMR spectrometers equipped with multiple receivers now enables the acquisition of several experiments simultaneously instead of one after the other. Here, we propose several variants of the CON experiment in which, during the recovery delay, a second two-dimensional experiment is acquired, either based on 1H detection (CON//HN) or on 15N detection (CON//btNH, CON//(H)CAN). The possibility to collect simultaneous snapshots of an IDP/IDR through different two-dimensional spectra provides a novel tool to follow chemical reactions, such as the occurrence of posttranslational modifications, as well as to study samples of limited lifetime such as cell lysates or whole cells.
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Affiliation(s)
- Marco Schiavina
- Magnetic Resonance Center and Department of Chemistry "Ugo Schiff," University of Florence, Sesto Fiorentino, Florence, Italy
| | - Maria Grazia Murrali
- Magnetic Resonance Center and Department of Chemistry "Ugo Schiff," University of Florence, Sesto Fiorentino, Florence, Italy
| | - Letizia Pontoriero
- Magnetic Resonance Center and Department of Chemistry "Ugo Schiff," University of Florence, Sesto Fiorentino, Florence, Italy
| | - Valerio Sainati
- Magnetic Resonance Center and Department of Chemistry "Ugo Schiff," University of Florence, Sesto Fiorentino, Florence, Italy
| | | | | | - Roberta Pierattelli
- Magnetic Resonance Center and Department of Chemistry "Ugo Schiff," University of Florence, Sesto Fiorentino, Florence, Italy.
| | - Isabella C Felli
- Magnetic Resonance Center and Department of Chemistry "Ugo Schiff," University of Florence, Sesto Fiorentino, Florence, Italy.
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6
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Cook EC, Sahu D, Bastidas M, Showalter SA. Solution Ensemble of the C-Terminal Domain from the Transcription Factor Pdx1 Resembles an Excluded Volume Polymer. J Phys Chem B 2018; 123:106-116. [PMID: 30525611 DOI: 10.1021/acs.jpcb.8b10051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The pancreatic and duodenal homeobox 1 (Pdx1) is an essential pancreatic transcription factor. The C-terminal intrinsically disordered domain of Pdx1 (Pdx1-C) has a heavily biased amino acid composition; most notably, 18 of 83 residues are proline, including a hexaproline cluster near the middle of the chain. For these reasons, Pdx1-C is an attractive target for structure characterization, given the availability of suitable methods. To determine the solution ensembles of disordered proteins, we have developed a suite of 13C direct-detect NMR experiments that provide high spectral quality, even in the presence of strong proline enrichment. Here, we have extended our suite of NMR experiments to include four new pulse programs designed to record backbone residual dipolar couplings in a 13C,15N-CON detection format. Using our NMR strategy, in combination with small-angle X-ray scattering measurements and Monte Carlo simulations, we have determined that Pdx1-C is extended in solution, with a radius of gyration and internal scaling similar to that of an excluded volume polymer, and a subtle tendency toward a collapsed structure to the N-terminal side of the hexaproline sequence. This structure leaves Pdx1-C exposed for interactions with trans-regulatory co-factors that contribute with Pdx1 to transcription control in the cell.
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7
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Burkholder NT, Medellin B, Irani S, Matthews W, Showalter SA, Zhang YJ. Chemical Tools for Studying the Impact of cis/trans Prolyl Isomerization on Signaling: A Case Study on RNA Polymerase II Phosphatase Activity and Specificity. Methods Enzymol 2018; 607:269-297. [PMID: 30149861 PMCID: PMC6701646 DOI: 10.1016/bs.mie.2018.04.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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] [Indexed: 10/14/2023]
Abstract
Proline isomerization is ubiquitous in proteins and is important for regulating important processes such as folding, recognition, and enzymatic activity. In humans, peptidyl-prolyl isomerase cis-trans isomerase NIMA interacting 1 (Pin1) is responsible for mediating fast conversion between cis- and trans-conformations of serine/threonine-proline (S/T-P) motifs in a large number of cellular pathways, many of which are involved in normal development as well as progression of several cancers and diseases. One of the major processes that Pin1 regulates is phosphatase activity against the RNA polymerase II C-terminal domain (RNAPII CTD). However, molecular tools capable of distinguishing the effects of proline conformation on phosphatase function have been lacking. A key tool that allows us to understand isomeric specificity of proteins toward their substrates is the usage of proline mimicking isosteres that are locked to prevent cis/trans-proline conversion. These locked isosteres can be incorporated into standard peptide synthesis and then used in replacement of native substrates in various experimental techniques such as kinetic and thermodynamic assays as well as X-ray crystallography. We will describe the application of these chemical tools in detail using CTD phosphatases as an example. We will also discuss alternative methods for analyzing the effect of proline conformation such as 13C NMR and the biological implications of proline isomeric specificity of proteins. The chemical and analytical tools presented in this chapter are widely applicable and should help elucidate many questions on the role of proline isomerization in biology.
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Affiliation(s)
| | - Brenda Medellin
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States
| | - Seema Irani
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, United States
| | - Wendy Matthews
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States
| | - Scott A Showalter
- Department of Chemistry, Pennsylvania State University, University Park, PA, United States; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, United States
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States.
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9
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Srb P, Nováček J, Kadeřávek P, Rabatinová A, Krásný L, Žídková J, Bobálová J, Sklenář V, Žídek L. Triple resonance ¹⁵Ν NMR relaxation experiments for studies of intrinsically disordered proteins. J Biomol NMR 2017; 69:133-146. [PMID: 29071460 DOI: 10.1007/s10858-017-0138-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 09/26/2017] [Indexed: 06/07/2023]
Abstract
Description of protein dynamics is known to be essential in understanding their function. Studies based on a well established [Formula: see text] NMR relaxation methodology have been applied to a large number of systems. However, the low dispersion of [Formula: see text] chemical shifts very often observed within intrinsically disordered proteins complicates utilization of standard 2D HN correlated spectra because a limited number of amino acids can be characterized. Here we present a suite of triple resonance HNCO-type NMR experiments for measurements of five [Formula: see text] relaxation parameters ([Formula: see text], [Formula: see text], NOE, cross-correlated relaxation rates [Formula: see text] and [Formula: see text]) in doubly [Formula: see text],[Formula: see text]-labeled proteins. We show that the third spectral dimension combined with non-uniform sampling provides relaxation rates for almost all residues of a protein with extremely poor chemical shift dispersion, the C terminal domain of [Formula: see text]-subunit of RNA polymerase from Bacillus subtilis. Comparison with data obtained using a sample labeled by [Formula: see text] only showed that the presence of [Formula: see text] has a negligible effect on [Formula: see text], [Formula: see text], and on the cross-relaxation rate (calculated from NOE and [Formula: see text]), and that these relaxation rates can be used to calculate accurate spectral density values. Partially [Formula: see text]-labeled sample was used to test if the observed increase of [Formula: see text] [Formula: see text] in the presence of [Formula: see text] corresponds to the [Formula: see text] dipole-dipole interactions in the [Formula: see text],[Formula: see text]-labeled sample.
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Affiliation(s)
- Pavel Srb
- Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí, 542/2, 166 10, Praha 6, Czech Republic
| | - Jiří Nováček
- Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Pavel Kadeřávek
- Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Alžbeta Rabatinová
- Laboratory of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic v.v.i., Videňská 1083, 142 20, Prague, Czech Republic
| | - Libor Krásný
- Laboratory of Molecular Genetics of Bacteria, Institute of Microbiology, Academy of Sciences of the Czech Republic v.v.i., Videňská 1083, 142 20, Prague, Czech Republic
| | - Jitka Žídková
- Institute of Analytical Chemistry of the Czech Academy of Sciences v.v.i., Veveří 97, 602 00, Brno, Czech Republic
| | - Janette Bobálová
- Institute of Analytical Chemistry of the Czech Academy of Sciences v.v.i., Veveří 97, 602 00, Brno, Czech Republic
| | - Vladimír Sklenář
- Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Lukáš Žídek
- Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
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10
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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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11
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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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12
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Fürtig B, Schnieders R, Richter C, Zetzsche H, Keyhani S, Helmling C, Kovacs H, Schwalbe H. Direct ¹³C-detected NMR experiments for mapping and characterization of hydrogen bonds in RNA. J Biomol NMR 2016; 64:207-221. [PMID: 26852414 DOI: 10.1007/s10858-016-0021-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 01/29/2016] [Indexed: 06/05/2023]
Abstract
In RNA secondary structure determination, it is essential to determine whether a nucleotide is base-paired and not. Base-pairing of nucleotides is mediated by hydrogen bonds. The NMR characterization of hydrogen bonds relies on experiments correlating the NMR resonances of exchangeable protons and can be best performed for structured parts of the RNA, where labile hydrogen atoms are protected from solvent exchange. Functionally important regions in RNA, however, frequently reveal increased dynamic disorder which often leads to NMR signals of exchangeable protons that are broadened beyond (1)H detection. Here, we develop (13)C direct detected experiments to observe all nucleotides in RNA irrespective of whether they are involved in hydrogen bonds or not. Exploiting the self-decoupling of scalar couplings due to the exchange process, the hydrogen bonding behavior of the hydrogen bond donor of each individual nucleotide can be determined. Furthermore, the adaption of HNN-COSY experiments for (13)C direct detection allows correlations of donor-acceptor pairs and the localization of hydrogen-bond acceptor nucleotides. The proposed (13)C direct detected experiments therefore provide information about molecular sites not amenable by conventional proton-detected methods. Such information makes the RNA secondary structure determination by NMR more accurate and helps to validate secondary structure predictions based on bioinformatics.
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Affiliation(s)
- Boris Fürtig
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany.
| | - Robbin Schnieders
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany
| | - Christian Richter
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany
| | - Heidi Zetzsche
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany
| | - Sara Keyhani
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany
| | - Christina Helmling
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany
| | - Helena Kovacs
- Bruker BioSpin, Industriestrasse 26, 8117, Fällanden, Switzerland
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ), Institute of Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe Universität Frankfurt, Max von Laue-Str. 7, 60438, Frankfurt, Germany.
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13
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Sahu D, Bastidas M, Lawrence CW, Noid WG, Showalter SA. Assessing Coupled Protein Folding and Binding Through Temperature-Dependent Isothermal Titration Calorimetry. Methods Enzymol 2016. [DOI: 10.1016/bs.mie.2015.07.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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14
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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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15
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Perez RB, Tischer A, Auton M, Whitten ST. Alanine and proline content modulate global sensitivity to discrete perturbations in disordered proteins. Proteins 2014; 82:3373-84. [PMID: 25244701 DOI: 10.1002/prot.24692] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/26/2014] [Accepted: 09/16/2014] [Indexed: 01/12/2023]
Abstract
Molecular transduction of biological signals is understood primarily in terms of the cooperative structural transitions of protein macromolecules, providing a mechanism through which discrete local structure perturbations affect global macromolecular properties. The recognition that proteins lacking tertiary stability, commonly referred to as intrinsically disordered proteins (IDPs), mediate key signaling pathways suggests that protein structures without cooperative intramolecular interactions may also have the ability to couple local and global structure changes. Presented here are results from experiments that measured and tested the ability of disordered proteins to couple local changes in structure to global changes in structure. Using the intrinsically disordered N-terminal region of the p53 protein as an experimental model, a set of proline (PRO) and alanine (ALA) to glycine (GLY) substitution variants were designed to modulate backbone conformational propensities without introducing non-native intramolecular interactions. The hydrodynamic radius (R(h)) was used to monitor changes in global structure. Circular dichroism spectroscopy showed that the GLY substitutions decreased polyproline II (PP(II)) propensities relative to the wild type, as expected, and fluorescence methods indicated that substitution-induced changes in R(h) were not associated with folding. The experiments showed that changes in local PP(II) structure cause changes in R(h) that are variable and that depend on the intrinsic chain propensities of PRO and ALA residues, demonstrating a mechanism for coupling local and global structure changes. Molecular simulations that model our results were used to extend the analysis to other proteins and illustrate the generality of the observed PRO and alanine effects on the structures of IDPs.
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Affiliation(s)
- Romel B Perez
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas
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Lawrence CW, Kumar S, Noid WG, Showalter SA. Role of Ordered Proteins in the Folding-Upon-Binding of Intrinsically Disordered Proteins. J Phys Chem Lett 2014; 5:833-838. [PMID: 26274075 DOI: 10.1021/jz402729x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this work, we quantitatively investigate the thermodynamic analogy between the folding of monomeric proteins and the interactions of intrinsically disordered proteins (IDPs). Motivated by the hypothesis that similar hydrophobic forces guide both globular protein folding and also IDP interactions, we present a unified experimental and computational investigation of the coupling between the folding and binding of the intrinsically disordered tail of FCP1 when interacting with the cooperatively folding winged-helix domain of Rap74. Our calorimetric measurements quantitatively demonstrate the significance of hydrophobic interactions for this binding event. Our computational studies indicate that IDPs relieve frustration at the surface of ordered proteins to generate a minimally frustrated complex that is strikingly similar to a globular monomeric protein. In summary, these results not only quantify the thermodynamic forces driving disordered protein interactions but also highlight the role of ordered proteins for IDP function.
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Affiliation(s)
- Chad W Lawrence
- §Department of Chemistry and †Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Sushant Kumar
- §Department of Chemistry and †Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - William G Noid
- §Department of Chemistry and †Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Scott A Showalter
- §Department of Chemistry and †Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Higo J, Umezawa K. Free-Energy Landscape of Intrinsically Disordered Proteins Investigated by All-Atom Multicanonical Molecular Dynamics. Advances in Experimental Medicine and Biology 2014. [DOI: 10.1007/978-3-319-02970-2_14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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18
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Sahu D, Bastidas M, Showalter SA. Generating NMR chemical shift assignments of intrinsically disordered proteins using carbon-detected NMR methods. Anal Biochem 2013; 449:17-25. [PMID: 24333248 DOI: 10.1016/j.ab.2013.12.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 11/26/2013] [Accepted: 12/02/2013] [Indexed: 10/25/2022]
Abstract
There is an extraordinary need to describe the structures of intrinsically disordered proteins (IDPs) due to their role in various biological processes involved in signaling and transcription. However, general study of IDPs by NMR spectroscopy is limited by the poor (1)H amide chemical shift dispersion typically observed in their spectra. Recently, (13)C direct-detected NMR spectroscopy has been recognized as enabling broad structural study of IDPs. Most notably, multidimensional experiments based on the (15)N,(13)C CON spectrum make complete chemical shift assignment feasible. Here we document a collection of NMR-based tools that efficiently lead to chemical shift assignment of IDPs, motivated by a case study of the C-terminal disordered region from the human pancreatic transcription factor Pdx1. Our strategy builds on the combination of two three-dimensional (3D) experiments, (HN-flip)N(CA)CON and 3D (HN-flip)N(CA)NCO, that enable daisy chain connections to be built along the IDP backbone, facilitated by acquisition of amino acid-specific (15)N,(13)C CON-detected experiments. Assignments are completed through carbon-detected, total correlation spectroscopy (TOCSY)-based side chain chemical shift measurement. Conducting our study required producing valuable modifications to many previously published pulse sequences, motivating us to announce the creation of a database of our pulse programs, which we make freely available through our website.
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Affiliation(s)
- Debashish Sahu
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Monique Bastidas
- 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.
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19
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Langridge TD, Tarver MJ, Whitten ST. Temperature effects on the hydrodynamic radius of the intrinsically disordered N-terminal region of the p53 protein. Proteins 2013; 82:668-78. [PMID: 24150971 DOI: 10.1002/prot.24449] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 09/20/2013] [Accepted: 10/10/2013] [Indexed: 01/15/2023]
Abstract
Intrinsically disordered proteins (IDPs) are often characterized in terms of the hydrodynamic radius, Rh . The Rh of IDPs are known to depend on fractional proline content and net charge, where increased numbers of proline residues and increased net charge cause larger Rh . Though sequence and charge effects on the Rh of IDPs have been studied, the temperature sensitivity has been noted only briefly. Reported here are Rh measurements in the temperature range of 5-75°C for the intrinsically disordered N-terminal region of the p53 protein, p53(1-93). Of note, the Rh of this protein fragment was highly sensitive to temperature, decreasing from 35 Å at 5°C to 26 Å at 75°C. Computer generated simulations of conformationally dynamic and disordered polypeptide chains were performed to provide a hypothesis for the heat-induced compaction of p53(1-93) structure, which was opposite to the heat-induced increase in Rh observed for a model folded protein. The simulations demonstrated that heat caused Rh to trend toward statistical coil values for both proteins, indicating that the effects of heat on p53(1-93) structure could be interpreted as thermal denaturation. The simulation data also predicted that proline content contributed minimally to the native Rh of p53(1-93), which was confirmed by measuring Rh for a substitution variant that had all 22 proline residues changed for glycine.
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Affiliation(s)
- Timothy D Langridge
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas, 78666
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20
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Kosol S, Contreras-Martos S, Cedeño C, Tompa P. Structural characterization of intrinsically disordered proteins by NMR spectroscopy. Molecules 2013; 18:10802-28. [PMID: 24008243 PMCID: PMC6269831 DOI: 10.3390/molecules180910802] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/19/2013] [Accepted: 08/30/2013] [Indexed: 01/25/2023] Open
Abstract
Recent advances in NMR methodology and techniques allow the structural investigation of biomolecules of increasing size with atomic resolution. NMR spectroscopy is especially well-suited for the study of intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) which are in general highly flexible and do not have a well-defined secondary or tertiary structure under functional conditions. In the last decade, the important role of IDPs in many essential cellular processes has become more evident as the lack of a stable tertiary structure of many protagonists in signal transduction, transcription regulation and cell-cycle regulation has been discovered. The growing demand for structural data of IDPs required the development and adaption of methods such as 13C-direct detected experiments, paramagnetic relaxation enhancements (PREs) or residual dipolar couplings (RDCs) for the study of ‘unstructured’ molecules in vitro and in-cell. The information obtained by NMR can be processed with novel computational tools to generate conformational ensembles that visualize the conformations IDPs sample under functional conditions. Here, we address NMR experiments and strategies that enable the generation of detailed structural models of IDPs.
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Affiliation(s)
- Simone Kosol
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
- Authors to whom correspondence should be addressed; E-Mails: (S.K.); (P.T.)
| | - Sara Contreras-Martos
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
| | - Cesyen Cedeño
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
| | - Peter Tompa
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels 1050, Belgium; E-Mails: (S.C.M.); (C.C.)
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest 1518, Hungary
- Authors to whom correspondence should be addressed; E-Mails: (S.K.); (P.T.)
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21
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Kumar S, Showalter SA, Noid WG. Native-based simulations of the binding interaction between RAP74 and the disordered FCP1 peptide. J Phys Chem B 2013; 117:3074-85. [PMID: 23387368 DOI: 10.1021/jp310293b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
By dephosphorylating the C-terminal domain (CTD) of RNA polymerase II (Pol II), the Transcription Factor IIF (TFIIF)-associating CTD phosphatase (FCP1) performs an essential function in recycling Pol II for subsequent rounds of transcription. The interaction between FCP1 and TFIIF is mediated by the disordered C-terminal tail of FCP1, which folds to form an α-helix upon binding the RAP74 subunit of TFIIF. The present work reports a structure-based simulation study of this interaction between the folded winged-helix domain of RAP74 and the disordered C-terminal tail of FCP1. The comparison of measured and simulated chemical shifts suggests that the FCP1 peptide samples 40-60% of its native helical structure in the unbound disordered ensemble. Free energy calculations suggest that productive binding begins when RAP74 makes hydrophobic contacts with the C-terminal region of the FCP1 peptide. The FCP1 peptide then folds into an amphipathic helix by zipping up the binding interface. The relative plasticity of FCP1 results in a more cooperative binding mechanism, allows for a greater diversity of pathways leading to the bound complex, and may also eliminate the need for "backtracking" from contacts that form out of sequence.
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Affiliation(s)
- Sushant Kumar
- Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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