1
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Hoare BL, Tippett DN, Kaur A, Cullum SA, Miljuš T, Koers EJ, Harwood CR, Dijon N, Holliday ND, Sykes DA, Veprintsev DB. ThermoBRET: A Ligand-Engagement Nanoscale Thermostability Assay Applied to GPCRs. Chembiochem 2024; 25:e202300459. [PMID: 37872746 DOI: 10.1002/cbic.202300459] [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: 06/22/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023]
Abstract
Measurements of membrane protein thermostability reflect ligand binding. Current thermostability assays often require protein purification or rely on pre-existing radiolabelled or fluorescent ligands, limiting their application to established targets. Alternative methods, such as fluorescence-detection size exclusion chromatography thermal shift, detect protein aggregation but are not amenable to high-throughput screening. Here, we present a ThermoBRET method to quantify the relative thermostability of G protein coupled receptors (GPCRs), using cannabinoid receptors (CB1 and CB2 ) and the β2 -adrenoceptor (β2 AR) as model systems. ThermoBRET reports receptor unfolding, does not need labelled ligands and can be used with non-purified proteins. It uses Bioluminescence Resonance Energy Transfer (BRET) between Nanoluciferase (Nluc) and a thiol-reactive fluorescent dye that binds cysteines exposed by unfolding. We demonstrate that the melting point (Tm ) of Nluc-fused GPCRs can be determined in non-purified detergent solubilised membrane preparations or solubilised whole cells, revealing differences in thermostability for different solubilising conditions and in the presence of stabilising ligands. We extended the range of the assay by developing the thermostable tsNLuc by incorporating mutations from the fragments of split-Nluc (Tm of 87 °C versus 59 °C). ThermoBRET allows the determination of GPCR thermostability, which is useful for protein purification optimisation and drug discovery screening.
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Affiliation(s)
- Bradley L Hoare
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Current address, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia
| | - David N Tippett
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Current address, Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Amandeep Kaur
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Sean A Cullum
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Tamara Miljuš
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Eline J Koers
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Clare R Harwood
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Nicola Dijon
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Nicholas D Holliday
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - David A Sykes
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Dmitry B Veprintsev
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
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2
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Otzen DE, Pedersen JN, Somavarapu AK, Clement A, Ji M, Petersen EH, Pedersen JS, Urban S, Schafer NP. Cys-labeling kinetics of membrane protein GlpG: a role for specific SDS binding and micelle changes? Biophys J 2021; 120:4115-4128. [PMID: 34370995 DOI: 10.1016/j.bpj.2021.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/20/2021] [Accepted: 08/03/2021] [Indexed: 01/01/2023] Open
Abstract
Empirically, α-helical membrane protein folding stability in surfactant micelles can be tuned by varying the mole fraction MFSDS of anionic (sodium dodecyl sulfate (SDS)) relative to nonionic (e.g., dodecyl maltoside (DDM)) surfactant, but we lack a satisfying physical explanation of this phenomenon. Cysteine labeling (CL) has thus far only been used to study the topology of membrane proteins, not their stability or folding behavior. Here, we use CL to investigate membrane protein folding in mixed DDM-SDS micelles. Labeling kinetics of the intramembrane protease GlpG are consistent with simple two-state unfolding-and-exchange rates for seven single-Cys GlpG variants over most of the explored MFSDS range, along with exchange from the native state at low MFSDS (which inconveniently precludes measurement of unfolding kinetics under native conditions). However, for two mutants, labeling rates decline with MFSDS at 0-0.2 MFSDS (i.e., native conditions). Thus, an increase in MFSDS seems to be a protective factor for these two positions, but not for the five others. We propose different scenarios to explain this and find the most plausible ones to involve preferential binding of SDS monomers to the site of CL (based on computational simulations) along with changes in size and shape of the mixed micelle with changing MFSDS (based on SAXS studies). These nonlinear impacts on protein stability highlights a multifaceted role for SDS in membrane protein denaturation, involving both direct interactions of monomeric SDS and changes in micelle size and shape along with the general effects on protein stability of changes in micelle composition.
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Affiliation(s)
- Daniel E Otzen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark.
| | - Jannik Nedergaard Pedersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Arun Kumar Somavarapu
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Anders Clement
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Ming Ji
- Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Emil Hartvig Petersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark; Department of Chemistry, Aarhus University, Aarhus C, Denmark
| | - Sinisa Urban
- Department of Molecular Biology & Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Nicholas P Schafer
- Interdisciplinary Nanoscience Center and Department of Molecular Biology and Genetics, Aarhus C, Denmark
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3
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Miljus T, Sykes DA, Harwood CR, Vuckovic Z, Veprintsev DB. GPCR Solubilization and Quality Control. Methods Mol Biol 2020; 2127:105-127. [PMID: 32112318 DOI: 10.1007/978-1-0716-0373-4_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
G protein-coupled receptors (GPCRs) are versatile membrane proteins involved in the regulation of many physiological processes and pathological conditions, making them interesting pharmacological targets. In order to study their structure and function, GPCRs are traditionally extracted from membranes using detergents. However, due to their hydrophobic nature, intrinsic instability in aqueous solutions, and their denaturing effects, the isolation of properly folded and functional GPCRs is not trivial. Therefore, it is of crucial importance to solubilize receptors under mild conditions and control the sample quality subsequently. Here we describe widely used methods for small-scale GPCR solubilization, followed by quality control based on fluorescence size-exclusion chromatography, SDS-PAGE, temperature-induced protein unfolding (CPM dye binding) and fluorescent ligand binding assay. These methods can easily be used to assess the thermostability and functionality of a GPCR sample exposed to different conditions, such as the use of various detergents, addition of lipids and ligands, making them valuable for obtaining an optimal sample quality for structural and functional studies.
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Affiliation(s)
- Tamara Miljus
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen PSI, Switzerland
- Department of Biology, ETH Zürich, Zürich, Switzerland
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - David A Sykes
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Clare R Harwood
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Ziva Vuckovic
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen PSI, Switzerland
- Department of Biology, ETH Zürich, Zürich, Switzerland
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Dmitry B Veprintsev
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen PSI, Switzerland.
- Department of Biology, ETH Zürich, Zürich, Switzerland.
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, UK.
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4
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Craven GB, Affron DP, Allen CE, Matthies S, Greener JG, Morgan RML, Tate EW, Armstrong A, Mann DJ. High-Throughput Kinetic Analysis for Target-Directed Covalent Ligand Discovery. Angew Chem Int Ed Engl 2018; 57:5257-5261. [PMID: 29480525 PMCID: PMC5947712 DOI: 10.1002/anie.201711825] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/16/2018] [Indexed: 01/10/2023]
Abstract
Cysteine‐reactive small molecules are used as chemical probes of biological systems and as medicines. Identifying high‐quality covalent ligands requires comprehensive kinetic analysis to distinguish selective binders from pan‐reactive compounds. Quantitative irreversible tethering (qIT), a general method for screening cysteine‐reactive small molecules based upon the maximization of kinetic selectivity, is described. This method was applied prospectively to discover covalent fragments that target the clinically important cell cycle regulator Cdk2. Crystal structures of the inhibitor complexes validate the approach and guide further optimization. The power of this technique is highlighted by the identification of a Cdk2‐selective allosteric (type IV) kinase inhibitor whose novel mode‐of‐action could be exploited therapeutically.
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Affiliation(s)
- Gregory B. Craven
- Department of ChemistryImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Dominic P. Affron
- Department of ChemistryImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Charlotte E. Allen
- Department of ChemistryImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Stefan Matthies
- Department of ChemistryImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Joe G. Greener
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Rhodri M. L. Morgan
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Edward W. Tate
- Department of ChemistryImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - Alan Armstrong
- Department of ChemistryImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
| | - David J. Mann
- Department of Life SciencesImperial College LondonSouth Kensington CampusLondonSW7 2AZUK
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5
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Craven GB, Affron DP, Allen CE, Matthies S, Greener JG, Morgan RML, Tate EW, Armstrong A, Mann DJ. High-Throughput Kinetic Analysis for Target-Directed Covalent Ligand Discovery. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201711825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Gregory B. Craven
- Department of Chemistry; Imperial College London; South Kensington Campus London SW7 2AZ UK
- Department of Life Sciences; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Dominic P. Affron
- Department of Chemistry; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Charlotte E. Allen
- Department of Chemistry; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Stefan Matthies
- Department of Chemistry; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Joe G. Greener
- Department of Life Sciences; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Rhodri M. L. Morgan
- Department of Life Sciences; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Edward W. Tate
- Department of Chemistry; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - Alan Armstrong
- Department of Chemistry; Imperial College London; South Kensington Campus London SW7 2AZ UK
| | - David J. Mann
- Department of Life Sciences; Imperial College London; South Kensington Campus London SW7 2AZ UK
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6
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Li B, Tunc-Ozdemir M, Urano D, Jia H, Werth EG, Mowrey DD, Hicks LM, Dokholyan NV, Torres MP, Jones AM. Tyrosine phosphorylation switching of a G protein. J Biol Chem 2018; 293:4752-4766. [PMID: 29382719 DOI: 10.1074/jbc.ra117.000163] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/26/2018] [Indexed: 01/08/2023] Open
Abstract
Heterotrimeric G protein complexes are molecular switches relaying extracellular signals sensed by G protein-coupled receptors (GPCRs) to downstream targets in the cytoplasm, which effect cellular responses. In the plant heterotrimeric GTPase cycle, GTP hydrolysis, rather than nucleotide exchange, is the rate-limiting reaction and is accelerated by a receptor-like regulator of G signaling (RGS) protein. We hypothesized that posttranslational modification of the Gα subunit in the G protein complex regulates the RGS-dependent GTPase cycle. Our structural analyses identified an invariant phosphorylated tyrosine residue (Tyr166 in the Arabidopsis Gα subunit AtGPA1) located in the intramolecular domain interface where nucleotide binding and hydrolysis occur. We also identified a receptor-like kinase that phosphorylates AtGPA1 in a Tyr166-dependent manner. Discrete molecular dynamics simulations predicted that phosphorylated Tyr166 forms a salt bridge in this interface and potentially affects the RGS protein-accelerated GTPase cycle. Using a Tyr166 phosphomimetic substitution, we found that the cognate RGS protein binds more tightly to the GDP-bound Gα substrate, consequently reducing its ability to accelerate GTPase activity. In conclusion, we propose that phosphorylation of Tyr166 in AtGPA1 changes the binding pattern with AtRGS1 and thereby attenuates the steady-state rate of the GTPase cycle. We coin this newly identified mechanism "substrate phosphoswitching."
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Affiliation(s)
- Bo Li
- Departments of Biology, Chapel Hill, North Carolina 27599
| | | | - Daisuke Urano
- Departments of Biology, Chapel Hill, North Carolina 27599; Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, 117604, Singapore
| | - Haiyan Jia
- Departments of Biology, Chapel Hill, North Carolina 27599
| | - Emily G Werth
- Department of Chemistry, Chapel Hill, North Carolina 27599
| | - David D Mowrey
- Biochemistry/Biophysics, Chapel Hill, North Carolina 27599
| | - Leslie M Hicks
- Department of Chemistry, Chapel Hill, North Carolina 27599
| | | | - Matthew P Torres
- Department of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Alan M Jones
- Departments of Biology, Chapel Hill, North Carolina 27599; Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599.
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7
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Isom DG, Page SC, Collins LB, Kapolka NJ, Taghon GJ, Dohlman HG. Coordinated regulation of intracellular pH by two glucose-sensing pathways in yeast. J Biol Chem 2017; 293:2318-2329. [PMID: 29284676 DOI: 10.1074/jbc.ra117.000422] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/22/2017] [Indexed: 12/19/2022] Open
Abstract
The yeast Saccharomyces cerevisiae employs multiple pathways to coordinate sugar availability and metabolism. Glucose and other sugars are detected by a G protein-coupled receptor, Gpr1, as well as a pair of transporter-like proteins, Rgt2 and Snf3. When glucose is limiting, however, an ATP-driven proton pump (Pma1) is inactivated, leading to a marked decrease in cytoplasmic pH. Here we determine the relative contribution of the two sugar-sensing pathways to pH regulation. Whereas cytoplasmic pH is strongly dependent on glucose abundance and is regulated by both glucose-sensing pathways, ATP is largely unaffected and therefore cannot account for the changes in Pma1 activity. These data suggest that the pH is a second messenger of the glucose-sensing pathways. We show further that different sugars differ in their ability to control cellular acidification, in the manner of inverse agonists. We conclude that the sugar-sensing pathways act via Pma1 to invoke coordinated changes in cellular pH and metabolism. More broadly, our findings support the emerging view that cellular systems have evolved the use of pH signals as a means of adapting to environmental stresses such as those caused by hypoxia, ischemia, and diabetes.
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Affiliation(s)
- Daniel G Isom
- From the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365, .,the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, and
| | - Stephani C Page
- From the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365
| | - Leonard B Collins
- the Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599-7432
| | - Nicholas J Kapolka
- the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, and
| | - Geoffrey J Taghon
- the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, and
| | - Henrik G Dohlman
- From the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365,
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8
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Trindade RV, Pinto AFM, Santos DS, Bizarro CV. Pulse Proteolysis and Precipitation for Target Identification. J Proteome Res 2016; 15:2236-45. [DOI: 10.1021/acs.jproteome.6b00214] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rogério V. Trindade
- Centro
de Pesquisas em Biologia Molecular e Funcional (CPBMF), Instituto
Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), 6681/92-A. Av. Ipiranga-TECNOPUC-Prédio 92A 90619-900, Porto Alegre, Rio Grande do Sul, Brazil
| | - Antônio F. M. Pinto
- Centro
de Pesquisas em Biologia Molecular e Funcional (CPBMF), Instituto
Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), 6681/92-A. Av. Ipiranga-TECNOPUC-Prédio 92A 90619-900, Porto Alegre, Rio Grande do Sul, Brazil
| | - Diógenes S. Santos
- Centro
de Pesquisas em Biologia Molecular e Funcional (CPBMF), Instituto
Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), 6681/92-A. Av. Ipiranga-TECNOPUC-Prédio 92A 90619-900, Porto Alegre, Rio Grande do Sul, Brazil
| | - Cristiano V. Bizarro
- Centro
de Pesquisas em Biologia Molecular e Funcional (CPBMF), Instituto
Nacional de Ciência e Tecnologia em Tuberculose (INCT-TB), Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), 6681/92-A. Av. Ipiranga-TECNOPUC-Prédio 92A 90619-900, Porto Alegre, Rio Grande do Sul, Brazil
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9
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Isom DG, Sridharan V, Dohlman HG. Regulation of Ras Paralog Thermostability by Networks of Buried Ionizable Groups. Biochemistry 2016; 55:534-42. [PMID: 26701741 DOI: 10.1021/acs.biochem.5b00901] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Protein folding is governed by a variety of molecular forces including hydrophobic and ionic interactions. Less is known about the molecular determinants of protein stability. Here we used a recently developed computer algorithm (pHinder) to investigate the relationship between buried charge and thermostability. Our analysis revealed that charge networks in the protein core are generally smaller in thermophilic organisms as compared to mesophilic organisms. To experimentally test whether core network size influences protein thermostability, we purified 18 paralogous Ras superfamily GTPases from yeast and determined their melting temperatures (Tm, or temperature at which 50% of the protein is unfolded). This analysis revealed a wide range of Tm values (35-63 °C) that correlated significantly (R = 0.87) with core network size. These results suggest that thermostability depends in part on the arrangement of ionizable side chains within a protein core. An improved capacity to predict protein thermostability may be useful for selecting the best candidates for protein crystallography, the development of protein-based therapeutics, as well as for industrial enzyme applications.
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Affiliation(s)
- Daniel G Isom
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Vishwajith Sridharan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
| | - Henrik G Dohlman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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10
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The experimental power of FR900359 to study Gq-regulated biological processes. Nat Commun 2015; 6:10156. [PMID: 26658454 PMCID: PMC4682109 DOI: 10.1038/ncomms10156] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 11/06/2015] [Indexed: 12/13/2022] Open
Abstract
Despite the discovery of heterotrimeric αβγ G proteins ∼25 years ago, their selective perturbation by cell-permeable inhibitors remains a fundamental challenge. Here we report that the plant-derived depsipeptide FR900359 (FR) is ideally suited to this task. Using a multifaceted approach we systematically characterize FR as a selective inhibitor of Gq/11/14 over all other mammalian Gα isoforms and elaborate its molecular mechanism of action. We also use FR to investigate whether inhibition of Gq proteins is an effective post-receptor strategy to target oncogenic signalling, using melanoma as a model system. FR suppresses many of the hallmark features that are central to the malignancy of melanoma cells, thereby providing new opportunities for therapeutic intervention. Just as pertussis toxin is used extensively to probe and inhibit the signalling of Gi/o proteins, we anticipate that FR will at least be its equivalent for investigating the biological relevance of Gq.
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11
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Hobbs GA, Mitchell LE, Arrington ME, Gunawardena HP, DeCristo MJ, Loeser RF, Chen X, Cox AD, Campbell SL. Redox regulation of Rac1 by thiol oxidation. Free Radic Biol Med 2015; 79:237-50. [PMID: 25289457 PMCID: PMC4708892 DOI: 10.1016/j.freeradbiomed.2014.09.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 09/17/2014] [Accepted: 09/22/2014] [Indexed: 01/24/2023]
Abstract
The Rac1 GTPase is an essential and ubiquitous protein that signals through numerous pathways to control critical cellular processes, including cell growth, morphology, and motility. Rac1 deletion is embryonic lethal, and its dysregulation or mutation can promote cancer, arthritis, cardiovascular disease, and neurological disorders. Rac1 activity is highly regulated by modulatory proteins and posttranslational modifications. Whereas much attention has been devoted to guanine nucleotide exchange factors that act on Rac1 to promote GTP loading and Rac1 activation, cellular oxidants may also regulate Rac1 activation by promoting guanine nucleotide exchange. Herein, we show that Rac1 contains a redox-sensitive cysteine (Cys(18)) that can be selectively oxidized at physiological pH because of its lowered pKa. Consistent with these observations, we show that Rac1 is glutathiolated in primary chondrocytes. Oxidation of Cys(18) by glutathione greatly perturbs Rac1 guanine nucleotide binding and promotes nucleotide exchange. As aspartate substitutions have been previously used to mimic cysteine oxidation, we characterized the biochemical properties of Rac1(C18D). We also evaluated Rac1(C18S) as a redox-insensitive variant and found that it retains structural and biochemical properties similar to those of Rac1(WT) but is resistant to thiol oxidation. In addition, Rac1(C18D), but not Rac1(C18S), shows greatly enhanced nucleotide exchange, similar to that observed for Rac1 oxidation by glutathione. We employed Rac1(C18D) in cell-based studies to assess whether this fast-cycling variant, which mimics Rac1 oxidation by glutathione, affects Rac1 activity and function. Expression of Rac1(C18D) in Swiss 3T3 cells showed greatly enhanced GTP-bound Rac1 relative to Rac1(WT) and the redox-insensitive Rac1(C18S) variant. Moreover, expression of Rac1(C18D) in HEK-293T cells greatly promoted lamellipodia formation. Our results suggest that Rac1 oxidation at Cys(18) is a novel posttranslational modification that upregulates Rac1 activity.
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Affiliation(s)
- G Aaron Hobbs
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260
| | - Lauren E Mitchell
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260
| | - Megan E Arrington
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260; Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290
| | - Harsha P Gunawardena
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260; Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Molly J DeCristo
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280; Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599-7365
| | - Richard F Loeser
- Department of Medicine and the Thurston Arthritis Research Center, University of North Carolina, Chapel Hill, NC 27599-7280
| | - Xian Chen
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260; Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Adrienne D Cox
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599-7365; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7295; Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC 27599-7512
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7295.
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12
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Tolbert CE, Thompson PM, Superfine R, Burridge K, Campbell SL. Phosphorylation at Y1065 in vinculin mediates actin bundling, cell spreading, and mechanical responses to force. Biochemistry 2014; 53:5526-36. [PMID: 25115937 PMCID: PMC4151700 DOI: 10.1021/bi500678x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
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Vinculin
is an essential structural adaptor protein that localizes
to sites of adhesion and is involved in a number of cell processes
including adhesion, spreading, motility, force transduction, and cell
survival. The C-terminal vinculin tail domain (Vt) contains the necessary
structural components to bind and cross-link actin filaments. Actin
binding to Vt induces a conformational change that promotes dimerization
through the C-terminal hairpin of Vt and enables actin filament cross-linking.
Here we show that Src phosphorylation of Y1065 within the C-terminal
hairpin regulates Vt-mediated actin bundling and provide a detailed
characterization of Y1065 mutations. Furthermore, we show that phosphorylation
at Y1065 plays a role in cell spreading and the response to the application
of mechanical force.
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Affiliation(s)
- Caitlin E Tolbert
- Department of Cell Biology and Physiology, ‡Department of Biochemistry and Biophysics, §Graduate Molecular and Cellular Biophysics Program, ∥Department of Physics and Astronomy, and ⊥the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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13
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Geer MA, Fitzgerald MC. Energetics-based methods for protein folding and stability measurements. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2014; 7:209-228. [PMID: 24896313 DOI: 10.1146/annurev-anchem-071213-020024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Over the past 15 years, a series of energetics-based techniques have been developed for the thermodynamic analysis of protein folding and stability. These techniques include Stability of Unpurified Proteins from Rates of amide H/D Exchange (SUPREX), pulse proteolysis, Stability of Proteins from Rates of Oxidation (SPROX), slow histidine H/D exchange, lysine amidination, and quantitative cysteine reactivity (QCR). The above techniques, which are the subject of this review, all utilize chemical or enzymatic modification reactions to probe the chemical denaturant- or temperature-induced equilibrium unfolding properties of proteins and protein-ligand complexes. They employ various mass spectrometry-, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-, and optical spectroscopy-based readouts that are particularly advantageous for high-throughput and in some cases multiplexed analyses. This has created the opportunity to use protein folding and stability measurements in new applications such as in high-throughput screening projects to identify novel protein ligands and in mode-of-action studies to identify protein targets of a particular ligand.
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Affiliation(s)
- M Ariel Geer
- Department of Chemistry, Duke University, Durham, North Carolina 27708-0346;
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14
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Dixit G, Baker R, Sacks CM, Torres MP, Dohlman HG. Guanine nucleotide-binding protein (Gα) endocytosis by a cascade of ubiquitin binding domain proteins is required for sustained morphogenesis and proper mating in yeast. J Biol Chem 2014; 289:15052-63. [PMID: 24722989 PMCID: PMC4031556 DOI: 10.1074/jbc.m114.566117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 04/07/2014] [Indexed: 01/10/2023] Open
Abstract
Heterotrimeric G proteins are well known to transmit signals from cell surface receptors to intracellular effector proteins. There is growing appreciation that G proteins are also present at endomembrane compartments, where they can potentially interact with a distinct set of signaling proteins. Here, we examine the cellular trafficking function of the G protein α subunit in yeast, Gpa1. Gpa1 contains a unique 109-amino acid insert within the α-helical domain that undergoes a variety of posttranslational modifications. Among these is monoubiquitination, catalyzed by the NEDD4 family ubiquitin ligase Rsp5. Using a newly optimized method for G protein purification together with biophysical measures of structure and function, we show that the ubiquitination domain does not influence enzyme activity. By screening a panel of 39 gene deletion mutants, each lacking a different ubiquitin binding domain protein, we identify seven that are necessary to deliver Gpa1 to the vacuole compartment including four proteins (Ede1, Bul1, Ddi1, and Rup1) previously not known to be involved in this process. Finally, we show that proper endocytosis of the G protein is needed for sustained cellular morphogenesis and mating in response to pheromone stimulation. We conclude that a cascade of ubiquitin-binding proteins serves to deliver the G protein to its final destination within the cell. In this instance and in contrast to the previously characterized visual system, endocytosis from the plasma membrane is needed for proper signal transduction rather than for signal desensitization.
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Affiliation(s)
- Gauri Dixit
- From the Department of Biochemistry and Biophysics
| | | | | | - Matthew P Torres
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Henrik G Dohlman
- From the Department of Biochemistry and Biophysics, Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 and
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15
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Hobbs GA, Gunawardena HP, Campbell SL. Biophysical and proteomic characterization strategies for cysteine modifications in Ras GTPases. Methods Mol Biol 2014; 1120:75-96. [PMID: 24470020 DOI: 10.1007/978-1-62703-791-4_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cysteine is one of the most reactive amino acids and is modified by a number of oxidants. The reactivity of cysteines is dependent on the thiol pK a; however, measuring cysteine pK a values is nontrivial. Ras family GTPases have been shown to contain a free cysteine that is sensitive to oxidation, and free radical-mediated oxidation of this cysteine has been shown to be activating. Here, we present a new technique that allows for measuring cysteine pK a values using a fluorescent detection system with the molecule 4-fluoro-7-aminosulfonylbenzofurazan (ABD-F). In addition, we also describe how to generate several oxidants. Lastly, we describe several mass spectrometry-based experiments and the necessary adjustments to the experiments to detect cysteine oxidation.
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Affiliation(s)
- G Aaron Hobbs
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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16
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Baker R, Wilkerson EM, Sumita K, Isom DG, Sasaki AT, Dohlman HG, Campbell SL. Differences in the regulation of K-Ras and H-Ras isoforms by monoubiquitination. J Biol Chem 2013; 288:36856-62. [PMID: 24247240 DOI: 10.1074/jbc.c113.525691] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Ras GTPases are signaling switches that control critical cellular processes including gene expression, differentiation, and apoptosis. The major Ras isoforms (K, H, and N) contain a conserved core GTPase domain, but have distinct biological functions. Among the three Ras isoforms there are clear differences in post-translational regulation, which contribute to differences in localization and signaling output. Modification by ubiquitination was recently reported to activate Ras signaling in cells, but the mechanisms of activation are not well understood. Here, we show that H-Ras is activated by monoubiquitination and that ubiquitination at Lys-117 accelerates intrinsic nucleotide exchange, thereby promoting GTP loading. This mechanism of Ras activation is distinct from K-Ras monoubiquitination at Lys-147, which leads to impaired regulator-mediated GTP hydrolysis. These findings reveal that different Ras isoforms are monoubiquitinated at distinct sites, with distinct mechanisms of action, but with a common ability to chronically activate the protein in the absence of a receptor signal or oncogenic mutation.
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Affiliation(s)
- Rachael Baker
- From the Departments of Biochemistry and Biophysics and
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17
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Isom DG, Sridharan V, Baker R, Clement ST, Smalley DM, Dohlman HG. Protons as second messenger regulators of G protein signaling. Mol Cell 2013; 51:531-8. [PMID: 23954348 DOI: 10.1016/j.molcel.2013.07.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 06/11/2013] [Accepted: 06/26/2013] [Indexed: 12/19/2022]
Abstract
In response to environmental stress, cells often generate pH signals that serve to protect vital cellular components and reprogram gene expression for survival. A major barrier to our understanding of this process has been the identification of signaling proteins that detect changes in intracellular pH. To identify candidate pH sensors, we developed a computer algorithm that searches proteins for networks of proton-binding sidechains. This analysis indicates that Gα subunits, the principal transducers of G protein-coupled receptor (GPCR) signals, are pH sensors. Our structure-based calculations and biophysical investigations reveal that Gα subunits contain networks of pH-sensing sidechains buried between their Ras and helical domains. Further, we show that proton binding induces changes in conformation that promote Gα phosphorylation and suppress receptor-initiated signaling. Together, our computational, biophysical, and cellular analyses reveal an unexpected function for G proteins as mediators of stress-response signaling.
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Affiliation(s)
- Daniel G Isom
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA.
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18
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Makley LN, Gestwicki JE. Expanding the number of 'druggable' targets: non-enzymes and protein-protein interactions. Chem Biol Drug Des 2013; 81:22-32. [PMID: 23253128 DOI: 10.1111/cbdd.12066] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Following sequencing and assembly of the human genome, the preferred methods for identification of new drug targets have changed dramatically. Modern tactics such as genome-wide association studies (GWAS) and deep sequencing are fundamentally different from the pharmacology-guided approaches used previously, in which knowledge of small molecule ligands acting at their cellular targets was the primary discovery engine. A consequence of the 'target-first, pharmacology-second' strategy is that many predicted drug targets are non-enzymes, such as scaffolding, regulatory or structural proteins, and their activities are often dependent on protein-protein interactions (PPIs). These types of targets create unique challenges to drug discovery efforts because enzymatic turnover cannot be used as a convenient surrogate for compound potency. Moreover, it is often challenging to predict how ligand binding to non-enzymes might affect changes in protein function and/or pathobiology. Thus, in the postgenomic era, targets might be strongly implicated by molecular biology-based methods, yet they often later earn the designation of 'undruggable'. Can the scope of available targets be widened to include these promising, but challenging, non-enzymes? In this review, we discuss advances in high-throughput screening (HTS) technology and chemical library design that are emerging to deal with these challenges.
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Affiliation(s)
- Leah N Makley
- Departments of Pathology, Biological Chemistry and the Interdisciplinary Program in Medicinal Chemistry, The Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216, USA
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19
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Abstract
Statistical analysis of protein sequences indicates an architecture for natural proteins in which amino acids are engaged in a sparse, hierarchical pattern of interactions in the tertiary structure. This architecture might be a key and distinguishing feature of evolved proteins-a design principle providing not only for foldability and high-performance function but also for robustness to perturbation and the capacity for rapid adaptation to new selection pressures. Here, we describe an approach for systematically testing this design principle for natural-like proteins by (1) computational design of synthetic sequences that gradually add or remove constraints along the hierarchy of interacting residues and (2) experimental testing of the designed sequences for folding and biochemical function. By this process, we hope to understand how the constraints on fold, function, and other aspects of fitness are organized within natural proteins, a first step in understanding the process of "design" by evolution.
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Affiliation(s)
- Kimberly A Reynolds
- Green Center for Systems Biology, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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20
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Baker R, Lewis SM, Sasaki AT, Wilkerson EM, Locasale JW, Cantley LC, Kuhlman B, Dohlman HG, Campbell SL. Site-specific monoubiquitination activates Ras by impeding GTPase-activating protein function. Nat Struct Mol Biol 2012. [PMID: 23178454 PMCID: PMC3537887 DOI: 10.1038/nsmb.2430] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cell growth and differentiation are controlled by growth factor receptors coupled to the GTPase Ras. Oncogenic mutations disrupt GTPase activity leading to persistent Ras signaling and cancer progression. Recent evidence indicates that monoubiquitination of Ras leads to Ras activation. Mutation of the primary site of monoubiquitination impairs the ability of activated K–Ras to promote tumor growth. To determine the mechanism of human Ras activation we chemically ubiquitinated the protein and analyzed its function by NMR, computational modeling, and biochemical activity measurements. We established that monoubiquitination has little effect on Ras GTP binding, GTP hydrolysis, or exchange factor activation, but severely abrogates the response to GTPase activating proteins in a site–specific manner. These findings reveal a new mechanism by which Ras can trigger persistent signaling in the absence of receptor activation or an oncogenic mutation.
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Affiliation(s)
- Rachael Baker
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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21
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Differences in intradomain and interdomain motion confer distinct activation properties to structurally similar Gα proteins. Proc Natl Acad Sci U S A 2012; 109:7275-9. [PMID: 22529365 DOI: 10.1073/pnas.1202943109] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteins with similar crystal structures can have dissimilar rates of substrate binding and catalysis. Here we used molecular dynamics simulations and biochemical analysis to determine the role of intradomain and interdomain motions in conferring distinct activation rates to two Gα proteins, Gα(i1) and GPA1. Despite high structural similarity, GPA1 can activate itself without a receptor, whereas Gα(i1) cannot. We found that motions in these proteins vary greatly in type and frequency. Whereas motion is greatest in the Ras domain of Gα(i1), it is greatest in helices αA and αB from the helical domain of GPA1. Using protein chimeras, we show that helix αA from GPA1 is sufficient to confer rapid activation to Gα(i1). Gα(i1) has less intradomain motion than GPA1 and instead displays interdomain displacement resembling that observed in a receptor-heterotrimer crystal complex. Thus, structurally similar proteins can have distinct atomic motions that confer distinct activation mechanisms.
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22
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Layton CJ, Hellinga HW. Quantitation of protein-protein interactions by thermal stability shift analysis. Protein Sci 2011; 20:1439-50. [PMID: 21674662 DOI: 10.1002/pro.674] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 05/31/2011] [Indexed: 11/11/2022]
Abstract
Thermal stability shift analysis is a powerful method for examining binding interactions in proteins. We demonstrate that under certain circumstances, protein-protein interactions can be quantitated by monitoring shifts in thermal stability using thermodynamic models and data analysis methods presented in this work. This method relies on the determination of protein stabilities from thermal unfolding experiments using fluorescent dyes such as SYPRO Orange that report on protein denaturation. Data collection is rapid and straightforward using readily available real-time polymerase chain reaction instrumentation. We present an approach for the analysis of the unfolding transitions corresponding to each partner to extract the affinity of the interaction between the proteins. This method does not require the construction of a titration series that brackets the dissociation constant. In thermal shift experiments, protein stability data are obtained at different temperatures according to the affinity- and concentration-dependent shifts in unfolding transition midpoints. Treatment of the temperature dependence of affinity is, therefore, intrinsic to this method and is developed in this study. We used the interaction between maltose-binding protein (MBP) and a thermostable synthetic ankyrin repeat protein (Off7) as an experimental test case because their unfolding transitions overlap minimally. We found that MBP is significantly stabilized by Off7. High experimental throughput is enabled by sample parallelization, and the ability to extract quantitative binding information at a single partner concentration. In a single experiment, we were able to quantify the affinities of a series of alanine mutants, covering a wide range of affinities (∼ 100 nM to ∼ 100 μM).
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Affiliation(s)
- Curtis J Layton
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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23
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Magliery TJ, Lavinder JJ, Sullivan BJ. Protein stability by number: high-throughput and statistical approaches to one of protein science's most difficult problems. Curr Opin Chem Biol 2011; 15:443-51. [PMID: 21498105 DOI: 10.1016/j.cbpa.2011.03.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/18/2011] [Accepted: 03/18/2011] [Indexed: 01/24/2023]
Abstract
Most proteins are only barely stable, which impedes research, complicates therapeutic applications, and makes proteins susceptible to pathologically destabilizing mutations. Our ability to predict the thermodynamic consequences of even single point mutations is still surprisingly limited, and established methods of measuring stability are slow. Recent advances are bringing protein stability studies into the high-throughput realm. Some methods are based on inferential read-outs such as activity, proteolytic resistance or split-protein fragment reassembly. Other methods use miniaturization of direct measurements, such as intrinsic fluorescence, H/D exchange, cysteine reactivity, aggregation and hydrophobic dye binding (DSF). Protein engineering based on statistical analysis (consensus and correlated occurrences of amino acids) is promising, but much work remains to understand and implement these methods.
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Affiliation(s)
- Thomas J Magliery
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA.
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