1
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Kirsch ZJ, Vachet RW. Proteins Can Withstand More Extensive Labeling while Providing Accurate Structural Information in Covalent Labeling-Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1030-1039. [PMID: 38581471 DOI: 10.1021/jasms.4c00043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/08/2024]
Abstract
Diethylpyrocarbonate (DEPC) covalent labeling-mass spectrometry (CL-MS) has been extensively utilized to study protein structure and interactions owing to its ease of use, commercial availability, and broad labeling of nucleophilic residues. During typical CL-MS experiments with DEPC, the extent of labeling is kept low to avoid any structural perturbations resulting from covalent modification of the protein. In this study, we demonstrate that proteins can be labeled more extensively via DEPC and still provide accurate structural information. To show this, we modeled labeling kinetics over a range of DEPC concentrations and used molecular dynamics simulations to investigate the molecular-level effects of extensive labeling on the protein structure. Our results indicate that higher extents of DEPC labeling do not significantly perturb the protein structure and can lead to improved precision, detectability of labeled peptides, and protein structural resolution. Furthermore, higher extents of labeling enable better identification of protein-ligand binding sites where lower extents of modification provide ambiguous results.
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Affiliation(s)
- Zachary J Kirsch
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Richard W Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
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2
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Hamuro Y. Interpretation of Hydrogen/Deuterium Exchange Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:819-828. [PMID: 38639434 PMCID: PMC11067899 DOI: 10.1021/jasms.4c00044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/29/2024] [Accepted: 04/02/2024] [Indexed: 04/20/2024]
Abstract
This paper sheds light on the meaning of hydrogen/deuterium exchange-mass spectrometry (HDX-MS) data. HDX-MS data provide not structural information but dynamic information on an analyte protein. First, the reaction mechanism of backbone amide HDX reaction is considered and the correlation between the parameters from an X-ray crystal structure and the protection factors of HDX reactions of cytochrome c is evaluated. The presence of H-bonds in a protein structure has a strong influence on HDX rates which represent protein dynamics, while the solvent accessibility only weakly affects the HDX rates. Second, the energy diagrams of the HDX reaction at each residue in the presence and absence of perturbation are described. Whereas the free energy change upon mutation can be directly measured by the HDX rates, the free energy change upon ligand binding may be complicated due to the presence of unbound analyte protein in the protein-ligand mixture. Third, the meanings of HDX and other biophysical techniques are explained using a hypothetical protein folding well. The shape of the protein folding well describes the protein dynamics and provides Boltzmann distribution of open and closed states which yield HDX protection factors, while a protein's crystal structure represents a snapshot near the bottom of the well. All biophysical data should be consistent yet provide different information because they monitor different parts of the same protein folding well.
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3
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Jethva PN, Gross ML. Hydrogen Deuterium Exchange and other Mass Spectrometry-based Approaches for Epitope Mapping. FRONTIERS IN ANALYTICAL SCIENCE 2023; 3:1118749. [PMID: 37746528 PMCID: PMC10512744 DOI: 10.3389/frans.2023.1118749] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Antigen-antibody interactions are a fundamental subset of protein-protein interactions responsible for the "survival of the fittest". Determining the interacting interface of the antigen, called an epitope, and that on the antibody, called a paratope, is crucial to antibody development. Because each antigen presents multiple epitopes (unique footprints), sophisticated approaches are required to determine the target region for a given antibody. Although X-ray crystallography, Cryo-EM, and nuclear magnetic resonance can provide atomic details of an epitope, they are often laborious, poor in throughput, and insensitive. Mass spectrometry-based approaches offer rapid turnaround, intermediate structural resolution, and virtually no size limit for the antigen, making them a vital approach for epitope mapping. In this review, we describe in detail the principles of hydrogen deuterium exchange mass spectrometry in application to epitope mapping. We also show that a combination of MS-based approaches can assist or complement epitope mapping and push the limit of structural resolution to the residue level. We describe in detail the MS methods used in epitope mapping, provide our perspective about the approaches, and focus on elucidating the role that HDX-MS is playing now and in the future by organizing a discussion centered around several improvements in prototype instrument/applications used for epitope mapping. At the end, we provide a tabular summary of the current literature on HDX-MS-based epitope mapping.
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Affiliation(s)
- Prashant N. Jethva
- Department of Chemistry, Washington University in St. Louis, St Louis, MO 63130, USA
| | - Michael L. Gross
- Department of Chemistry, Washington University in St. Louis, St Louis, MO 63130, USA
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4
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Cornwell O, Ault JR. Fast photochemical oxidation of proteins coupled with mass spectrometry. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140829. [PMID: 35933084 DOI: 10.1016/j.bbapap.2022.140829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/17/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Fast photochemical oxidation of proteins (FPOP) is a hydroxyl radical footprinting approach whereby radicals, produced by UV laser photolysis of hydrogen peroxide, induce oxidation of amino acid side-chains. Mass Spectrometry (MS) is employed to locate and quantify the resulting irreversible, covalent oxidations to use as a surrogate for side-chain solvent accessibility. Modulation of oxidation levels under different conditions allows for the characterisation of protein conformation, dynamics and binding epitopes. FPOP has been applied to structurally diverse and biopharmaceutically relevant systems from small, monomeric aggregation-prone proteins to proteome-wide analysis of whole organisms. This review evaluates the current state of FPOP, the progress needed to address data analysis bottlenecks, particularly for residue-level analysis, and highlights significant developments of the FPOP platform that have enabled its versatility and complementarity to other structural biology techniques.
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Affiliation(s)
- Owen Cornwell
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow SK9 4AX, UK
| | - James R Ault
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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5
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Yassaghi G, Kukačka Z, Fiala J, Kavan D, Halada P, Volný M, Novák P. Top-Down Detection of Oxidative Protein Footprinting by Collision-Induced Dissociation, Electron-Transfer Dissociation, and Electron-Capture Dissociation. Anal Chem 2022; 94:9993-10002. [PMID: 35797180 DOI: 10.1021/acs.analchem.1c05476] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fast photochemical oxidation of proteins (FPOP) footprinting is a structural mass spectrometry method that maps proteins by fast and irreversible chemical reactions. The position of oxidative modification reflects solvent accessibility and site reactivity and thus provides information about protein conformation, structural dynamics, and interactions. Bottom-up mass spectrometry is an established standard method to analyze FPOP samples. In the bottom-up approach, all forms of the protein are digested together by a protease of choice, which results in a mixture of peptides from various subpopulations of proteins with varying degrees of photochemical oxidation. Here, we investigate the possibility to analyze a specifically selected population of only singly oxidized proteins. This requires utilization of more specific top-down mass spectrometry approaches. The key element of any top-down experiment is the selection of a suitable method of ion isolation, excitation, and fragmentation. Here, we employ and compare collision-induced dissociation, electron-transfer dissociation, and electron-capture dissociation combined with multi-continuous accumulation of selected ions. A singly oxidized subpopulation of FPOP-labeled ubiquitin was used to optimize the method. The top-down approach in FPOP is limited to smaller proteins, but its usefulness was demonstrated by using it to visualize structural changes induced by co-factor removal from the holo/apo myoglobin system. The top-down data were compared with the literature and with the bottom-up data set obtained on the same samples. The top-down results were found to be in good agreement, which indicates that monitoring a singly oxidized FPOP ion population by the top-down approach is a functional workflow for oxidative protein footprinting.
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Affiliation(s)
- Ghazaleh Yassaghi
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic
| | - Zdeněk Kukačka
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic
| | - Jan Fiala
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic.,Faculty of Science, Charles University, Albertov 6, Prague 2 128 00, Czech Republic
| | - Daniel Kavan
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic.,Faculty of Science, Charles University, Albertov 6, Prague 2 128 00, Czech Republic
| | - Petr Halada
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic
| | - Michael Volný
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic
| | - Petr Novák
- Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague 4 142 20, Czech Republic
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6
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Sun J, Li W, Gross ML. Advances in mass spectrometry-based footprinting of membrane proteins. Proteomics 2022; 22:e2100222. [PMID: 35290716 PMCID: PMC10493193 DOI: 10.1002/pmic.202100222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 11/09/2022]
Abstract
Structural biology is entering an exciting time where many new high-resolution structures of large complexes and membrane proteins (MPs) are determined regularly. These advances have been driven by over 15 years of technological improvements, first in macromolecular crystallography, and recently in cryo-electron microscopy. Obtaining information about MP higher order structure and interactions is also a frontier, important but challenging owing to their unique properties and the need to choose suitable detergents/lipids for their study. The development of mass spectrometry (MS), both instruments and methodology in the past 10 years, has also advanced it as a complementary method to study MP structure and interactions. In this review, we discuss advances in MS-based footprinting for MPs and highlight recent methodologies that offer new promise for MP study by chemical footprinting and mass spectrometry.
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Affiliation(s)
- Jie Sun
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
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7
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Vallejo DD, Rojas Ramírez C, Parson KF, Han Y, Gadkari VV, Ruotolo BT. Mass Spectrometry Methods for Measuring Protein Stability. Chem Rev 2022; 122:7690-7719. [PMID: 35316030 DOI: 10.1021/acs.chemrev.1c00857] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mass spectrometry is a central technology in the life sciences, providing our most comprehensive account of the molecular inventory of the cell. In parallel with developments in mass spectrometry technologies targeting such assessments of cellular composition, mass spectrometry tools have emerged as versatile probes of biomolecular stability. In this review, we cover recent advancements in this branch of mass spectrometry that target proteins, a centrally important class of macromolecules that accounts for most biochemical functions and drug targets. Our efforts cover tools such as hydrogen-deuterium exchange, chemical cross-linking, ion mobility, collision induced unfolding, and other techniques capable of stability assessments on a proteomic scale. In addition, we focus on a range of application areas where mass spectrometry-driven protein stability measurements have made notable impacts, including studies of membrane proteins, heat shock proteins, amyloidogenic proteins, and biotherapeutics. We conclude by briefly discussing the future of this vibrant and fast-moving area of research.
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Affiliation(s)
- Daniel D Vallejo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Carolina Rojas Ramírez
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kristine F Parson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yilin Han
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Varun V Gadkari
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Brandon T Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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8
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Lin Y, Gross ML. Mass Spectrometry-Based Structural Proteomics for Metal Ion/Protein Binding Studies. Biomolecules 2022; 12:135. [PMID: 35053283 PMCID: PMC8773722 DOI: 10.3390/biom12010135] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/13/2022] [Accepted: 01/13/2022] [Indexed: 01/01/2023] Open
Abstract
Metal ions are critical for the biological and physiological functions of many proteins. Mass spectrometry (MS)-based structural proteomics is an ever-growing field that has been adopted to study protein and metal ion interactions. Native MS offers information on metal binding and its stoichiometry. Footprinting approaches coupled with MS, including hydrogen/deuterium exchange (HDX), "fast photochemical oxidation of proteins" (FPOP) and targeted amino-acid labeling, identify binding sites and regions undergoing conformational changes. MS-based titration methods, including "protein-ligand interactions by mass spectrometry, titration and HD exchange" (PLIMSTEX) and "ligand titration, fast photochemical oxidation of proteins and mass spectrometry" (LITPOMS), afford binding stoichiometry, binding affinity, and binding order. These MS-based structural proteomics approaches, their applications to answer questions regarding metal ion protein interactions, their limitations, and recent and potential improvements are discussed here. This review serves as a demonstration of the capabilities of these tools and as an introduction to wider applications to solve other questions.
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Affiliation(s)
- Yanchun Lin
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
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9
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McKenzie-Coe A, Montes NS, Jones LM. Hydroxyl Radical Protein Footprinting: A Mass Spectrometry-Based Structural Method for Studying the Higher Order Structure of Proteins. Chem Rev 2021; 122:7532-7561. [PMID: 34633178 DOI: 10.1021/acs.chemrev.1c00432] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hydroxyl radical protein footprinting (HRPF) coupled to mass spectrometry has been successfully used to investigate a plethora of protein-related questions. The method, which utilizes hydroxyl radicals to oxidatively modify solvent-accessible amino acids, can inform on protein interaction sites and regions of conformational change. Hydroxyl radical-based footprinting was originally developed to study nucleic acids, but coupling the method with mass spectrometry has enabled the study of proteins. The method has undergone several advancements since its inception that have increased its utility for more varied applications such as protein folding and the study of biotherapeutics. In addition, recent innovations have led to the study of increasingly complex systems including cell lysates and intact cells. Technological advances have also increased throughput and allowed for better control of experimental conditions. In this review, we provide a brief history of the field of HRPF and detail recent innovations and applications in the field.
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Affiliation(s)
- Alan McKenzie-Coe
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Nicholas S Montes
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
| | - Lisa M Jones
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201, United States
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10
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Fenton-Chemistry-Based Oxidative Modification of Proteins Reflects Their Conformation. Int J Mol Sci 2021; 22:ijms22189927. [PMID: 34576105 PMCID: PMC8469487 DOI: 10.3390/ijms22189927] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 09/09/2021] [Accepted: 09/11/2021] [Indexed: 11/25/2022] Open
Abstract
In order to understand protein structure to a sufficient extent for, e.g., drug discovery, no single technique can provide satisfactory information on both the lowest-energy conformation and on dynamic changes over time (the ‘four-dimensional’ protein structure). Instead, a combination of complementary techniques is required. Mass spectrometry methods have shown promise in addressing protein dynamics, but often rely on the use of high-end commercial or custom instruments. Here, we apply well-established chemistry to conformation-sensitive oxidative protein labelling on a timescale of a few seconds, followed by analysis through a routine protein analysis workflow. For a set of model proteins, we show that site selectivity of labelling can indeed be rationalised in terms of known structural information, and that conformational changes induced by ligand binding are reflected in the modification pattern. In addition to conventional bottom-up analysis, further insights are obtained from intact mass measurement and native mass spectrometry. We believe that this method will provide a valuable and robust addition to the ‘toolbox’ of mass spectrometry researchers studying higher-order protein structure.
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11
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Sharp JS, Chea EE, Misra SK, Orlando R, Popov M, Egan RW, Holman D, Weinberger SR. Flash Oxidation (FOX) System: A Novel Laser-Free Fast Photochemical Oxidation Protein Footprinting Platform. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1601-1609. [PMID: 33872496 PMCID: PMC8812269 DOI: 10.1021/jasms.0c00471] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Hydroxyl radical protein footprinting (HRPF) is a powerful and flexible technique for probing changes in protein topography. With the development of the fast photochemical oxidation of proteins (FPOP), it became possible for researchers to perform HRPF in their laboratory on a very short time scale. While FPOP has grown significantly in popularity since its inception, adoption remains limited due to technical and safety issues involved in the operation of a hazardous Class IV UV laser and irreproducibility often caused by improper laser operation and/or differential radical scavenging by various sample components. Here, we present a new integrated FOX (Flash OXidation) Protein Footprinting System. This platform delivers sample via flow injection to a facile and safe-to-use high-pressure flash lamp with a flash duration of 10 μs fwhm. Integrated optics collect the radiant light and focus it into the lumen of a capillary flow cell. An inline radical dosimeter measures the hydroxyl radical dose delivered and allows for real-time compensation for differential radical scavenging. A programmable fraction collector collects and quenches only the sample that received the desired effective hydroxyl radical dose, diverting the carrier liquid and improperly oxidized sample to waste. We demonstrate the utility of the FOX Protein Footprinting System by determining the epitope of TNFα recognized by adalimumab. We successfully identify the surface of the protein that serves as the epitope for adalimumab, identifying four of the five regions previously noted by X-ray crystallography while seeing no changes in peptides not involved in the epitope interface. The FOX Protein Footprinting System allows for FPOP-like experiments with real-time dosimetry in a safe, compact, and integrated benchtop platform.
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Affiliation(s)
- Joshua S. Sharp
- GenNext Technologies, Inc., Half Moon Bay, CA 94019
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, Mississippi 38677
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677
- Correspondence to Joshua S. Sharp,
| | | | - Sandeep K. Misra
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, Mississippi 38677
| | - Ron Orlando
- GenNext Technologies, Inc., Half Moon Bay, CA 94019
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602
- GlycoScientific, Athens, GA 30602
| | | | | | - David Holman
- GenNext Technologies, Inc., Half Moon Bay, CA 94019
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12
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Cornwell O, Ault JR, Bond NJ, Radford SE, Ashcroft AE. Investigation of D76N β 2-Microglobulin Using Protein Footprinting and Structural Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1583-1592. [PMID: 33586970 PMCID: PMC9282677 DOI: 10.1021/jasms.0c00438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
NMR studies and X-ray crystallography have shown that the structures of the 99-residue amyloidogenic protein β2-microglobulin (β2m) and its more aggregation-prone variant, D76N, are indistinguishable, and hence, the reason for the striking difference in their aggregation propensities remains elusive. Here, we have employed two protein footprinting methods, hydrogen-deuterium exchange (HDX) and fast photochemical oxidation of proteins (FPOP), in conjunction with ion mobility-mass spectrometry, to probe the differences in conformational dynamics of the two proteins. Using HDX-MS, a clear difference in HDX protection is observed between these two proteins in the E-F loop (residues 70-77) which contains the D76N substitution, with a significantly higher deuterium uptake being observed in the variant protein. Conversely, following FPOP-MS only minimal differences in the level of oxidation between the two proteins are observed in the E-F loop region, suggesting only modest side-chain movements in that area. Together the HDX-MS and FPOP-MS data suggest that a tangible perturbation to the hydrogen-bonding network in the E-F loop has taken place in the D76N variant and furthermore illustrate the benefit of using multiple complementary footprinting methods to address subtle, but possibly biologically important, differences between highly similar proteins.
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Affiliation(s)
- Owen Cornwell
- Biopharmaceuticals
R & D, AstraZeneca, Granta Park, Cambridge CB21 6GP, U.K.
| | - James R. Ault
- Astbury
Centre for Structural Molecular Biology & School of Molecular
and Cellular Biology, University of Leeds, Leeds LS2 9JT, U.K.
| | - Nicholas J. Bond
- Biopharmaceuticals
R & D, AstraZeneca, Granta Park, Cambridge CB21 6GP, U.K.
| | - Sheena E. Radford
- Astbury
Centre for Structural Molecular Biology & School of Molecular
and Cellular Biology, University of Leeds, Leeds LS2 9JT, U.K.
| | - Alison E. Ashcroft
- Astbury
Centre for Structural Molecular Biology & School of Molecular
and Cellular Biology, University of Leeds, Leeds LS2 9JT, U.K.
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13
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Cheng Z, Mobley C, Misra SK, Gadepalli RS, Hammond RI, Brown LS, Rimoldi JM, Sharp JS. Self-Organized Amphiphiles Are Poor Hydroxyl Radical Scavengers in Fast Photochemical Oxidation of Proteins Experiments. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1155-1161. [PMID: 33881849 PMCID: PMC8790760 DOI: 10.1021/jasms.0c00457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Analysis of membrane protein topography using fast photochemical oxidation of proteins (FPOP) has been reported in recent years but is still underrepresented in literature. Based on the hydroxyl radical reactivity of lipids and other amphiphiles, it is believed that the membrane environment acts as a hydroxyl radical scavenger decreasing effective hydroxyl radical doses and resulting in less observed oxidation of proteins. We found no significant change in bulk solvent radical scavenging activity upon the addition of disrupted cellular membranes up to 25600 cells/μL using an inline radical dosimeter. We confirmed the nonscavenging nature of the membrane in bulk solution with the FPOP results of a soluble model protein in the presence of cell membranes, which showed no significant difference in oxidation with or without membranes. The use of detergents revealed that, while soluble detergent below the critical micelle concentration is a potent hydroxyl radical scavenger, additional detergent has little to no hydroxyl radical scavenging effect once the critical micelle concentration is reached. Examination of both an extracellular peptide of the integral membrane protein bacteriorhodopsin as well as a novel hydroxyl radical dosimeter tethered to a Triton X-series amphiphile indicate that proximity to the membrane surface greatly decreases reaction with hydroxyl radicals, even though the oxidation target is equally solvent accessible. These results suggest that the observed reduced oxidation of solvent-accessible surfaces of integral membrane proteins is due to the high local concentration of radical scavengers in the membrane or membrane mimetics competing for the local concentration of hydroxyl radicals.
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Affiliation(s)
- Zhi Cheng
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
| | - Charles Mobley
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
| | - Sandeep K. Misra
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
| | - Rama S. Gadepalli
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
| | - Rachel I. Hammond
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
| | - Leonid S. Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - John M. Rimoldi
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
| | - Joshua S. Sharp
- Department of Biomolecular Sciences, University of Mississippi, University, MS 38677
- Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677
- GenNext Technologies, Inc. Half Moon Bay, CA 94019
- Correspondence to
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14
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Beveridge R, Calabrese AN. Structural Proteomics Methods to Interrogate the Conformations and Dynamics of Intrinsically Disordered Proteins. Front Chem 2021; 9:603639. [PMID: 33791275 PMCID: PMC8006314 DOI: 10.3389/fchem.2021.603639] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/19/2021] [Indexed: 12/21/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) and regions of intrinsic disorder (IDRs) are abundant in proteomes and are essential for many biological processes. Thus, they are often implicated in disease mechanisms, including neurodegeneration and cancer. The flexible nature of IDPs and IDRs provides many advantages, including (but not limited to) overcoming steric restrictions in binding, facilitating posttranslational modifications, and achieving high binding specificity with low affinity. IDPs adopt a heterogeneous structural ensemble, in contrast to typical folded proteins, making it challenging to interrogate their structure using conventional tools. Structural mass spectrometry (MS) methods are playing an increasingly important role in characterizing the structure and function of IDPs and IDRs, enabled by advances in the design of instrumentation and the development of new workflows, including in native MS, ion mobility MS, top-down MS, hydrogen-deuterium exchange MS, crosslinking MS, and covalent labeling. Here, we describe the advantages of these methods that make them ideal to study IDPs and highlight recent applications where these tools have underpinned new insights into IDP structure and function that would be difficult to elucidate using other methods.
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Affiliation(s)
- Rebecca Beveridge
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, United Kingdom
| | - Antonio N. Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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15
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Yin V, Holzscherer D, Konermann L. Delineating Heme-Mediated versus Direct Protein Oxidation in Peroxidase-Activated Cytochrome c by Top-Down Mass Spectrometry. Biochemistry 2020; 59:4108-4117. [PMID: 32991149 DOI: 10.1021/acs.biochem.0c00609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Oxidation of key residues in cytochrome c (cyt c) by chloramine T (CT) converts the protein from an electron transporter to a peroxidase. This peroxidase-activated state represents an important model system for exploring the early steps of apoptosis. CT-induced transformations include oxidation of the distal heme ligand Met80 (MetO, +16 Da) and carbonylation (LysCHO, -1 Da) in the range of Lys53/55/72/73. Remarkably, the 15 remaining Lys residues in cyt c are not susceptible to carbonylation. The cause of this unusual selectivity is unknown. Here we applied top-down mass spectrometry (MS) to examine whether CT-induced oxidation is catalyzed by heme. To this end, we compared the behavior of cyt c with (holo-cyt c) and without heme (apoSS-cyt c). CT caused MetO formation at Met80 for both holo- and apoSS-cyt c, implying that this transformation can proceed independently of heme. The aldehyde-specific label Girard's reagent T (GRT) reacted with oxidized holo-cyt c, consistent with the presence of several LysCHO. In contrast, oxidized apo-cyt c did not react with GRT, revealing that LysCHO forms only in the presence of heme. The heme dependence of LysCHO formation was further confirmed using microperoxidase-11 (MP11). CT exposure of apoSS-cyt c in the presence of MP11 caused extensive nonselective LysCHO formation. Our results imply that the selectivity of LysCHO formation at Lys53/55/72/73 in holo-cyt c is caused by the spatial proximity of these sites to the reactive (distal) heme face. Overall, this work highlights the utility of top-down MS for unravelling complex oxidative modifications.
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Affiliation(s)
- Victor Yin
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Derek Holzscherer
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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16
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Misra SK, Sharp JS. Enabling Real-Time Compensation in Fast Photochemical Oxidations of Proteins for the Determination of Protein Topography Changes. J Vis Exp 2020. [PMID: 32955502 DOI: 10.3791/61580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Fast photochemical oxidation of proteins (FPOP) is a mass spectrometry-based structural biology technique that probes the solvent-accessible surface area of proteins. This technique relies on the reaction of amino acid side chains with hydroxyl radicals freely diffusing in solution. FPOP generates these radicals in situ by laser photolysis of hydrogen peroxide, creating a burst of hydroxyl radicals that is depleted on the order of a microsecond. When these hydroxyl radicals react with a solvent-accessible amino acid side chain, the reaction products exhibit a mass shift that can be measured and quantified by mass spectrometry. Since the rate of reaction of an amino acid depends in part on the average solvent accessible surface of that amino acid, measured changes in the amount of oxidation of a given region of a protein can be directly correlated to changes in the solvent accessibility of that region between different conformations (e.g., ligand-bound versus ligand-free, monomer vs. aggregate, etc.) FPOP has been applied in a number of problems in biology, including protein-protein interactions, protein conformational changes, and protein-ligand binding. As the available concentration of hydroxyl radicals varies based on many experimental conditions in the FPOP experiment, it is important to monitor the effective radical dose to which the protein analyte is exposed. This monitoring is efficiently achieved by incorporating an inline dosimeter to measure the signal from the FPOP reaction, with laser fluence adjusted in real-time to achieve the desired amount of oxidation. With this compensation, changes in protein topography reflecting conformational changes, ligand-binding surfaces, and/or protein-protein interaction interfaces can be determined in heterogeneous samples using relatively low sample amounts.
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Affiliation(s)
- Sandeep K Misra
- Department of Biomolecular Sciences, University of Mississippi
| | - Joshua S Sharp
- Department of Biomolecular Sciences, University of Mississippi; Department of Chemistry and Biochemistry, University of Mississippi; GenNext Technologies, Inc.;
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17
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Potter ZE, Lau HT, Chakraborty S, Fang L, Guttman M, Ong SE, Fowler DM, Maly DJ. Parallel Chemoselective Profiling for Mapping Protein Structure. Cell Chem Biol 2020; 27:1084-1096.e4. [PMID: 32649906 PMCID: PMC7484201 DOI: 10.1016/j.chembiol.2020.06.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/27/2020] [Accepted: 06/19/2020] [Indexed: 01/01/2023]
Abstract
Solution-based structural techniques complement high-resolution structural data by providing insight into the oft-missed links between protein structure and dynamics. Here, we present Parallel Chemoselective Profiling, a solution-based structural method for characterizing protein structure and dynamics. Our method utilizes deep mutational scanning saturation mutagenesis data to install amino acid residues with specific chemistries at defined positions on the solvent-exposed surface of a protein. Differences in the extent of labeling of installed mutant residues are quantified using targeted mass spectrometry, reporting on each residue's local environment and structural dynamics. Using our method, we studied how conformation-selective, ATP-competitive inhibitors affect the local and global structure and dynamics of full-length Src kinase. Our results highlight how parallel chemoselective profiling can be used to study a dynamic multi-domain protein, and suggest that our method will be a useful addition to the relatively small toolkit of existing protein footprinting techniques.
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Affiliation(s)
- Zachary E Potter
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Ho-Tak Lau
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Sujata Chakraborty
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Linglan Fang
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Miklos Guttman
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Shao-En Ong
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA; Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Dustin J Maly
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA; Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
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18
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Garcia NK, Sreedhara A, Deperalta G, Wecksler AT. Optimizing Hydroxyl Radical Footprinting Analysis of Biotherapeutics Using Internal Standard Dosimetry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1563-1571. [PMID: 32407079 DOI: 10.1021/jasms.0c00146] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Hydroxyl radical footprinting-mass spectrometry (HRF-MS) is a powerful technique for measuring protein structure by quantitating the solvent accessibility of amino acid side-chains; and when used in comparative analysis, HRF-MS data can provide detailed information on changes in protein structure. However, consistently controlling the amount of hydroxyl radical labeling of a protein requires the precise understanding of both the amount of radicals generated and half-life of the radicals in solution. The latter is particularly important for applications such as protein-protein and protein-ligand interactions, which may have different characteristics such as intrinsic reactivity and buffer components, and can cause differences in radical scavenging (herein termed "scavenging potential") between samples. To address this inherent challenge with HRF-MS analysis, we describe the comprehensive implementation of an internal standard (IS) dosimeter peptide leucine enkephalin (LeuEnk) for measuring the scavenging potential of pharmaceutically relevant proteins and formulation components. This further enabled evaluation of the critical method parameters affecting the scavenging potential of samples subjected to HRF-MS using fast photochemical oxidation of proteins. We demonstrate a direct correlation between the oxidation of the IS peptide and biotherapeutic target proteins, and show the oxidation of the IS can be used as a guide for ensuring equivalent scavenging potentials when comparing multiple samples. Establishing this strategy enables optimization of sample parameters, a system suitability approach, normalization of data, and comparison/harmonization of HRF-MS analysis across different laboratories.
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Affiliation(s)
- Natalie K Garcia
- Protein Analytical Chemistry, Genentech Inc., South San Francisco, 1 DNA Way, South San Francisco, California 94080, United States
| | - Alavattam Sreedhara
- Late Stage Pharmaceutical Development, Genentech Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Galahad Deperalta
- Protein Analytical Chemistry, Genentech Inc., South San Francisco, 1 DNA Way, South San Francisco, California 94080, United States
| | - Aaron T Wecksler
- Protein Analytical Chemistry, Genentech Inc., South San Francisco, 1 DNA Way, South San Francisco, California 94080, United States
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19
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Espino JA, Zhang Z, Jones LM. Chemical Penetration Enhancers Increase Hydrogen Peroxide Uptake in C. elegans for In Vivo Fast Photochemical Oxidation of Proteins. J Proteome Res 2020; 19:3708-3715. [PMID: 32506919 PMCID: PMC7861136 DOI: 10.1021/acs.jproteome.0c00245] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Fast photochemical oxidation of proteins (FPOP) is a hydroxyl radical protein
footprinting method that covalently labels solvent-accessible amino acids by photolysis
of hydrogen peroxide. Recently, we expanded the use of FPOP for in vivo
(IV-FPOP) covalent labeling in C. elegans. In initial IV-FPOP studies,
545 proteins were oxidatively modified in all body systems within the worm. Here, with
the use of chemical penetration enhancers (CPEs), we increased the number of modified
proteins as well as the number of modifications per protein to gain more structural
information. CPEs aid in the delivery of hydrogen peroxide inside C.
elegans by disturbing the highly ordered lipid bilayer of the worm cuticle
without affecting worm viability. IV-FPOP experiments performed using the CPE azone
showed an increase in oxidatively modified proteins and peptides. This increase
correlated with greater hydrogen peroxide uptake by C. elegans
quantified using a chemical fluorophore demonstrating the efficacy of using CPEs with
IV-FPOP. Mass spectrometry proteomics data are available via ProteomeXchange with
identifier PXD019290.
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Affiliation(s)
- Jessica A Espino
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21202, United States
| | - Zhihui Zhang
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21202, United States
| | - Lisa M Jones
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21202, United States
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20
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Liu XR, Zhang MM, Gross ML. Mass Spectrometry-Based Protein Footprinting for Higher-Order Structure Analysis: Fundamentals and Applications. Chem Rev 2020; 120:4355-4454. [PMID: 32319757 PMCID: PMC7531764 DOI: 10.1021/acs.chemrev.9b00815] [Citation(s) in RCA: 122] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Proteins adopt different higher-order structures (HOS) to enable their unique biological functions. Understanding the complexities of protein higher-order structures and dynamics requires integrated approaches, where mass spectrometry (MS) is now positioned to play a key role. One of those approaches is protein footprinting. Although the initial demonstration of footprinting was for the HOS determination of protein/nucleic acid binding, the concept was later adapted to MS-based protein HOS analysis, through which different covalent labeling approaches "mark" the solvent accessible surface area (SASA) of proteins to reflect protein HOS. Hydrogen-deuterium exchange (HDX), where deuterium in D2O replaces hydrogen of the backbone amides, is the most common example of footprinting. Its advantage is that the footprint reflects SASA and hydrogen bonding, whereas one drawback is the labeling is reversible. Another example of footprinting is slow irreversible labeling of functional groups on amino acid side chains by targeted reagents with high specificity, probing structural changes at selected sites. A third footprinting approach is by reactions with fast, irreversible labeling species that are highly reactive and footprint broadly several amino acid residue side chains on the time scale of submilliseconds. All of these covalent labeling approaches combine to constitute a problem-solving toolbox that enables mass spectrometry as a valuable tool for HOS elucidation. As there has been a growing need for MS-based protein footprinting in both academia and industry owing to its high throughput capability, prompt availability, and high spatial resolution, we present a summary of the history, descriptions, principles, mechanisms, and applications of these covalent labeling approaches. Moreover, their applications are highlighted according to the biological questions they can answer. This review is intended as a tutorial for MS-based protein HOS elucidation and as a reference for investigators seeking a MS-based tool to address structural questions in protein science.
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Affiliation(s)
| | | | - Michael L. Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA, 63130
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21
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Kaltashov IA, Bobst CE, Pawlowski J, Wang G. Mass spectrometry-based methods in characterization of the higher order structure of protein therapeutics. J Pharm Biomed Anal 2020; 184:113169. [PMID: 32092629 DOI: 10.1016/j.jpba.2020.113169] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/06/2020] [Accepted: 02/11/2020] [Indexed: 12/31/2022]
Abstract
Higher order structure of protein therapeutics is an important quality attribute, which dictates both potency and safety. While modern experimental biophysics offers an impressive arsenal of state-of-the-art tools that can be used for the characterization of higher order structure, many of them are poorly suited for the characterization of biopharmaceutical products. As a result, these analyses were traditionally carried out using classical techniques that provide relatively low information content. Over the past decade, mass spectrometry made a dramatic debut in this field, enabling the characterization of higher order structure of biopharmaceuticals as complex as monoclonal antibodies at a level of detail that was previously unattainable. At present, mass spectrometry is an integral part of the analytical toolbox across the industry, which is critical not only for quality control efforts, but also for discovery and development.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA.
| | - Cedric E Bobst
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Jake Pawlowski
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Guanbo Wang
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu Province, PR China
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22
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Roush AE, Riaz M, Misra SK, Weinberger SR, Sharp JS. Intrinsic Buffer Hydroxyl Radical Dosimetry Using Tris(hydroxymethyl)aminomethane. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:169-172. [PMID: 32031409 PMCID: PMC7650270 DOI: 10.1021/jasms.9b00088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Fast photochemical oxidation of proteins (FPOP) is a powerful covalent labeling tool that uses hydroxyl radicals generated by laser flash photolysis of hydrogen peroxide to footprint protein surfaces. Because radical production varies with many experimental parameters, hydroxyl radical dosimeters have been introduced to track the effective radical dosage experienced by the protein analyte. FPOP experiments performed using adenine optical radical dosimetry containing protein in Tris buffer demonstrated unusual dosimetry behavior. We have investigated the behavior of Tris under oxidative conditions in detail. We find that Tris can act as a novel gain-of-signal optical hydroxyl radical dosimeter in FPOP experiments. This new dosimeter is also amenable to inline real-time monitoring, thereby allowing real-time adjustments to compensate for differences in samples for their quenching ability.
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Affiliation(s)
- Addison E Roush
- Department of BioMolecular Sciences , University of Mississippi , Oxford , Mississippi 38677 , United States
- Department of Chemistry and Biochemistry , University of Mississippi , Oxford , Mississippi 38677 , United States
| | - Mohammad Riaz
- Department of BioMolecular Sciences , University of Mississippi , Oxford , Mississippi 38677 , United States
| | - Sandeep K Misra
- Department of BioMolecular Sciences , University of Mississippi , Oxford , Mississippi 38677 , United States
| | - Scot R Weinberger
- GenNext Technologies, Inc. , Montara , California 94037 , United States
| | - Joshua S Sharp
- Department of BioMolecular Sciences , University of Mississippi , Oxford , Mississippi 38677 , United States
- Department of Chemistry and Biochemistry , University of Mississippi , Oxford , Mississippi 38677 , United States
- GenNext Technologies, Inc. , Montara , California 94037 , United States
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23
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Ziemianowicz DS, MacCallum JL, Schriemer DC. Correlation between Labeling Yield and Surface Accessibility in Covalent Labeling Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:207-216. [PMID: 32031402 DOI: 10.1021/jasms.9b00083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The functional properties of a protein are strongly influenced by its topography, or the solvent-facing contour map of its surface. Together with crosslinking, covalent labeling mass spectrometry (CL-MS) has the potential to contribute topographical data through the measurement of surface accessibility. However, recent efforts to correlate measures of surface accessibility with labeling yield have been met with mixed success. Most applications of CL-MS involve differential analysis of protein interactions (i.e., footprinting experiments) where such inconsistencies have limited effect. Extending CL-MS into structural analysis requires an improved evaluation of the relationship between labeling and surface exposure. In this study, we applied recently developed diazirine reagents to obtain deep coverage of the large motor domain of Eg5 (a mitotic kinesin), and together with computational methods we correlated labeling yields with accessibility data in a number of ways. We observe that correlations can indeed be seen at a local structural level, but these correlations do not extend across the structure. The lack of correlation arises from the influence of protein dynamics and chemical composition on reagent partitioning and, thus, also on labeling yield. We conclude that our use of CL-MS data should be considered in light of "chemical accessibility" rather than "solvent accessibility" and suggest that CL-MS data would be a useful tool in the fundamental study of protein-solute interactions.
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Affiliation(s)
- Daniel S Ziemianowicz
- Department of Biochemistry and Molecular Biology , University of Calgary , Calgary , Alberta , Canada T2N 4N1
- Robson DNA Science Centre, Arnie Charbonneau Cancer Institute , University of Calgary , Calgary , Alberta , Canada T2N 4N1
| | - Justin L MacCallum
- Department of Chemistry , University of Calgary , Calgary , Alberta , Canada T2N 4N1
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology , University of Calgary , Calgary , Alberta , Canada T2N 4N1
- Robson DNA Science Centre, Arnie Charbonneau Cancer Institute , University of Calgary , Calgary , Alberta , Canada T2N 4N1
- Department of Chemistry , University of Calgary , Calgary , Alberta , Canada T2N 4N1
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24
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Cornwell O, Bond NJ, Radford SE, Ashcroft AE. Long-Range Conformational Changes in Monoclonal Antibodies Revealed Using FPOP-LC-MS/MS. Anal Chem 2019; 91:15163-15170. [DOI: 10.1021/acs.analchem.9b03958] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Owen Cornwell
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, U.K
| | - Nicholas J. Bond
- Analytical Sciences, BioPharmaceutical Development, BioPharmaceuticals R&D, AstraZeneca, Granta Park, Cambridge, CB21 6GH, U.K
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, U.K
| | - Alison E. Ashcroft
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, U.K
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25
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Dülfer J, Kadek A, Kopicki JD, Krichel B, Uetrecht C. Structural mass spectrometry goes viral. Adv Virus Res 2019; 105:189-238. [PMID: 31522705 DOI: 10.1016/bs.aivir.2019.07.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Over the last 20 years, mass spectrometry (MS), with its ability to analyze small sample amounts with high speed and sensitivity, has more and more entered the field of structural virology, aiming to investigate the structure and dynamics of viral proteins as close to their native environment as possible. The use of non-perturbing labels in hydrogen-deuterium exchange MS allows for the analysis of interactions between viral proteins and host cell factors as well as their dynamic responses to the environment. Cross-linking MS, on the other hand, can analyze interactions in viral protein complexes and identify virus-host interactions in cells. Native MS allows transferring viral proteins, complexes and capsids into the gas phase and has broken boundaries to overcome size limitations, so that now even the analysis of intact virions is possible. Different MS approaches not only inform about size, stability, interactions and dynamics of virus assemblies, but also bridge the gap to other biophysical techniques, providing valuable constraints for integrative structural modeling of viral complex assemblies that are often inaccessible by single technique approaches. In this review, recent advances are highlighted, clearly showing that structural MS approaches in virology are moving towards systems biology and ever more experiments are performed on cellular level.
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Affiliation(s)
- Jasmin Dülfer
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Alan Kadek
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany; European XFEL GmbH, Schenefeld, Germany
| | - Janine-Denise Kopicki
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Boris Krichel
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Charlotte Uetrecht
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany; European XFEL GmbH, Schenefeld, Germany.
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26
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Maleknia SD, Downard KM. Protein Footprinting with Radical Probe Mass Spectrometry- Two Decades of Achievement. Protein Pept Lett 2019; 26:4-15. [PMID: 30484400 DOI: 10.2174/0929866526666181128124241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/31/2018] [Accepted: 09/11/2018] [Indexed: 01/19/2023]
Abstract
BACKGROUND Radical Probe Mass Spectrometry (RP-MS) describes a pioneering methodology in structural biology that enables the study of protein structures, their interactions, and dynamics on fast timescales (down to sub-milliseconds). Hydroxyl radicals (•OH) generated directly from water within aqueous solutions induce the oxidation of reactive, solvent accessible amino acid side chains that are then analyzed by mass spectrometry. Introduced in 1998 at the American Society for Mass Spectrometry annual conference, RP-MS was first published on in 1999. OBJECTIVE This review article describes developments and applications of the RP-MS methodology over the past two decades. METHODS The RP-MS method has been variously referred to as synchrotron X-ray radiolysis footprinting, Hydroxyl Radical Protein Footprinting (HRPF), X-ray Footprinting with Mass Spectrometry (XF-MS), Fast Photochemical Oxidation of Proteins (FPOP), oxidative labelling, covalent oxidative labelling, and even the Stability of Proteins from Rates of Oxidation (SPROX). RESULTS The article describes the utility of hydroxyl radicals as a protein structural probe, the advantages of RP-MS in comparison to other MS-based approaches, its proof of concept using ion mobility mass spectrometry, its application to protein structure, folding, complex and aggregation studies, its extension to study the onset of protein damage, its implementation using a high throughput sample loading approach, and the development of protein docking algorithms to aid with data analysis and visualization. CONCLUSION RP-MS represents a powerful new structural approach that can aid in our understanding of the structure and functions of proteins, and the impact of sustained oxidation on proteins in disease pathogenesis.
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Affiliation(s)
- Simin D Maleknia
- School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, NSW, Australia
| | - Kevin M Downard
- Infectious Disease Responses Laboratory, University of New South Wales-Medicine, Sydney, NSW, Australia
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27
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Garcia NK, Deperalta G, Wecksler AT. Current Trends in Biotherapeutic Higher Order Structure Characterization by Irreversible Covalent Footprinting Mass Spectrometry. Protein Pept Lett 2019; 26:35-43. [PMID: 30484396 DOI: 10.2174/0929866526666181128141953] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/01/2018] [Accepted: 10/29/2018] [Indexed: 12/26/2022]
Abstract
BACKGROUND Biotherapeutics, particularly monoclonal antibodies (mAbs), are a maturing class of drugs capable of treating a wide range of diseases. Therapeutic function and solutionstability are linked to the proper three-dimensional organization of the primary sequence into Higher Order Structure (HOS) as well as the timescales of protein motions (dynamics). Methods that directly monitor protein HOS and dynamics are important for mapping therapeutically relevant protein-protein interactions and assessing properly folded structures. Irreversible covalent protein footprinting Mass Spectrometry (MS) tools, such as site-specific amino acid labeling and hydroxyl radical footprinting are analytical techniques capable of monitoring the side chain solvent accessibility influenced by tertiary and quaternary structure. Here we discuss the methodology, examples of biotherapeutic applications, and the future directions of irreversible covalent protein footprinting MS in biotherapeutic research and development. CONCLUSION Bottom-up mass spectrometry using irreversible labeling techniques provide valuable information for characterizing solution-phase protein structure. Examples range from epitope mapping and protein-ligand interactions, to probing challenging structures of membrane proteins. By paring these techniques with hydrogen-deuterium exchange, spectroscopic analysis, or static-phase structural data such as crystallography or electron microscopy, a comprehensive understanding of protein structure can be obtained.
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Affiliation(s)
- Natalie K Garcia
- Department of Protein Analytical Chemistry, Genentech Inc., South San Francisco, CA 94080, United States
| | - Galahad Deperalta
- Department of Protein Analytical Chemistry, Genentech Inc., South San Francisco, CA 94080, United States
| | - Aaron T Wecksler
- Department of Protein Analytical Chemistry, Genentech Inc., South San Francisco, CA 94080, United States
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28
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Shi L, Gross ML. Fast Photochemical Oxidation of Proteins Coupled with Mass Spectrometry. Protein Pept Lett 2019; 26:27-34. [PMID: 30484399 DOI: 10.2174/0929866526666181128124554] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/30/2018] [Accepted: 09/27/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Determination of the composition and some structural features of macromolecules can be achieved by using structural proteomics approaches coupled with mass spectrometry (MS). One approach is hydroxyl radical protein footprinting whereby amino-acid side chains are modified with reactive reagents to modify irreversibly a protein side chain. The outcomes, when deciphered with mass-spectrometry-based proteomics, can increase our knowledge of structure, assembly, and conformational dynamics of macromolecules in solution. Generating the hydroxyl radicals by laser irradiation, Hambly and Gross developed the approach of Fast Photochemical Oxidation of Proteins (FPOP), which labels proteins on the sub millisecond time scale and provides, with MS analysis, deeper understanding of protein structure and protein-ligand and protein- protein interactions. This review highlights the fundamentals of FPOP and provides descriptions of hydroxyl-radical and other radical and carbene generation, of the hydroxyl labeling of proteins, and of determination of protein modification sites. We also summarize some recent applications of FPOP coupled with MS in protein footprinting. CONCLUSION We survey results that show the capability of FPOP for qualitatively measuring protein solvent accessibility on the residue level. To make these approaches more valuable, we describe recent method developments that increase FPOP's quantitative capacity and increase the spatial protein sequence coverage. To improve FPOP further, several new labeling reagents including carbenes and other radicals have been developed. These growing improvements will allow oxidative- footprinting methods coupled with MS to play an increasingly significant role in determining the structure and dynamics of macromolecules and their assemblies.
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Affiliation(s)
- Liuqing Shi
- Department of Chemistry, Washington University, St. Louis, MO 63130, United States
| | - Michael L Gross
- Department of Chemistry, Washington University, St. Louis, MO 63130, United States
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29
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Sheng Y, Capri J, Waring A, Valentine JS, Whitelegge J. Exposure of Solvent-Inaccessible Regions in the Amyloidogenic Protein Human SOD1 Determined by Hydroxyl Radical Footprinting. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:218-226. [PMID: 30328005 PMCID: PMC6347482 DOI: 10.1007/s13361-018-2075-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/18/2018] [Accepted: 09/22/2018] [Indexed: 06/08/2023]
Abstract
Solvent-accessibility change plays a critical role in protein misfolding and aggregation, the culprit for several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Mass spectrometry-based hydroxyl radical (·OH) protein footprinting has evolved as a powerful and fast tool in elucidating protein solvent accessibility. In this work, we used fast photochemical oxidation of protein (FPOP) hydroxyl radical (·OH) footprinting to investigate solvent accessibility in human copper-zinc superoxide dismutase (SOD1), misfolded or aggregated forms of which underlie a portion of ALS cases. ·OH-mediated modifications to 56 residues were detected with locations largely as predicted based on X-ray crystallography data, while the interior of SOD1 β-barrel is hydrophobic and solvent-inaccessible and thus protected from modification. There were, however, two notable exceptions-two closely located residues inside the β-barrel, predicted to have minimal or no solvent accessibility, that were found modified by FPOP (Phe20 and Ile112). Molecular dynamics (MD) simulations were consistent with differential access of peroxide versus quencher to SOD1's interior complicating surface accessibility considerations. Modification of these two residues could potentially be explained either by local motions of the β-barrel that increased peroxide/solvent accessibility to the interior or by oxidative events within the interior that might include long-distance radical transfer to buried sites. Overall, comparison of modification patterns for the metal-free apoprotein versus zinc-bound forms demonstrated that binding of zinc protected the electrostatic loop and organized the copper-binding site. Our study highlights SOD1 hydrophobic groups that may contribute to early events in aggregation and discusses caveats to surface accessibility conclusions. Graphical Abstract.
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Affiliation(s)
- Yuewei Sheng
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Joseph Capri
- The Pasarow Mass Spectrometry Laboratory, University of California, Los Angeles, CA, USA
| | - Alan Waring
- Department of Medicine, University of California, Los Angeles, CA, USA
| | | | - Julian Whitelegge
- The Pasarow Mass Spectrometry Laboratory, University of California, Los Angeles, CA, USA.
- The Brain Research Institute, University of California, Los Angeles, CA, USA.
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30
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Cornwell O, Radford SE, Ashcroft AE, Ault JR. Comparing Hydrogen Deuterium Exchange and Fast Photochemical Oxidation of Proteins: a Structural Characterisation of Wild-Type and ΔN6 β 2-Microglobulin. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:2413-2426. [PMID: 30267362 PMCID: PMC6276068 DOI: 10.1007/s13361-018-2067-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/07/2018] [Accepted: 09/10/2018] [Indexed: 05/23/2023]
Abstract
Hydrogen deuterium exchange (HDX) coupled to mass spectrometry (MS) is a well-established technique employed in the field of structural MS to probe the solvent accessibility, dynamics and hydrogen bonding of backbone amides in proteins. By contrast, fast photochemical oxidation of proteins (FPOP) uses hydroxyl radicals, liberated from the photolysis of hydrogen peroxide, to covalently label solvent accessible amino acid side chains on the microsecond-millisecond timescale. Here, we use these two techniques to study the structural and dynamical differences between the protein β2-microglobulin (β2m) and its amyloidogenic truncation variant, ΔN6. We show that HDX and FPOP highlight structural/dynamical differences in regions of the proteins, localised to the region surrounding the N-terminal truncation. Further, we demonstrate that, with carefully optimised LC-MS conditions, FPOP data can probe solvent accessibility at the sub-amino acid level, and that these data can be interpreted meaningfully to gain more detailed understanding of the local environment and orientation of the side chains in protein structures. Graphical Abstract ᅟ.
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Affiliation(s)
- Owen Cornwell
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Alison E Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
| | - James R Ault
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
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31
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Calabrese AN, Radford SE. Mass spectrometry-enabled structural biology of membrane proteins. Methods 2018; 147:187-205. [DOI: 10.1016/j.ymeth.2018.02.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/30/2018] [Accepted: 02/21/2018] [Indexed: 01/01/2023] Open
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32
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Limpikirati P, Liu T, Vachet RW. Covalent labeling-mass spectrometry with non-specific reagents for studying protein structure and interactions. Methods 2018; 144:79-93. [PMID: 29630925 PMCID: PMC6051898 DOI: 10.1016/j.ymeth.2018.04.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
Using mass spectrometry (MS) to obtain information about a higher order structure of protein requires that a protein's structural properties are encoded into the mass of that protein. Covalent labeling (CL) with reagents that can irreversibly modify solvent accessible amino acid side chains is an effective way to encode structural information into the mass of a protein, as this information can be read-out in a straightforward manner using standard MS-based proteomics techniques. The differential reactivity of proteins under two or more conditions can be used to distinguish protein topologies, conformations, and/or binding sites. CL-MS methods have been effectively used for the structural analysis of proteins and protein complexes, particularly for systems that are difficult to study by other more traditional biochemical techniques. This review provides an overview of the non-specific CL approaches that have been combined with MS with a particular emphasis on the reagents that are commonly used, including hydroxyl radicals, carbenes, and diethylpyrocarbonate. We describe the reagent and protein factors that affect the reactivity of amino acid side chains. We also include details about experimental design and workflow, data analysis, recent applications, and some future prospects of CL-MS methods.
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Affiliation(s)
| | - Tianying Liu
- Department of Chemistry, University of Massachusetts Amherst, MA 01003, United States
| | - Richard W Vachet
- Department of Chemistry, University of Massachusetts Amherst, MA 01003, United States.
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33
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Reading E. Structural Mass Spectrometry of Membrane Proteins within Their Native Lipid Environments. Chemistry 2018; 24:13391-13398. [PMID: 29672954 DOI: 10.1002/chem.201801556] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Indexed: 01/22/2023]
Abstract
Mass spectrometry has emerged as an important structural biology tool for understanding membrane protein structure, function, and dynamics. Generally, structural mass spectrometry of membrane proteins has been performed on purified or reconstituted systems which lack the native lipid membrane and cellular environments. However, there has been progress in the use and adaptations of these methods for probing membrane proteins within increasingly more native contexts. In this Concept article the use and utility of structural mass spectrometry techniques for studying membrane proteins within native environments are highlighted.
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Affiliation(s)
- Eamonn Reading
- Department of Chemistry, King's College London, 7 Trinity Street, SE1 1DB, London, UK
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34
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Implementing fast photochemical oxidation of proteins (FPOP) as a footprinting approach to solve diverse problems in structural biology. Methods 2018; 144:94-103. [PMID: 29800613 DOI: 10.1016/j.ymeth.2018.05.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/18/2018] [Accepted: 05/19/2018] [Indexed: 11/24/2022] Open
Abstract
Fast photochemical oxidation of proteins (FPOP) is a footprinting technique used in mass spectrometry-based structural proteomics. It has been applied to solve a variety of problems in different areas of biology. A FPOP platform requires a laser, optics, and sample flow path properly assembled to enable fast footprinting. Sample preparation, buffer conditions, and reagent concentrations are essential to obtain reasonable oxidations on proteins. FPOP samples can be analyzed by LC-MS methods to measure the modification extent, which is a function of the solvent-accessible surface area of the protein. The platform can be expanded to accommodate several new approaches, including dose-response studies, new footprinting reagents, and two-laser pump-probe experiments. Here, we briefly review FPOP applications and in a detailed manner describe the procedures to set up an FPOP protein footprinting platform.
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35
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Kiselar J, Chance MR. High-Resolution Hydroxyl Radical Protein Footprinting: Biophysics Tool for Drug Discovery. Annu Rev Biophys 2018. [DOI: 10.1146/annurev-biophys-070317-033123] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hydroxyl radical footprinting (HRF) of proteins with mass spectrometry (MS) is a widespread approach for assessing protein structure. Hydroxyl radicals react with a wide variety of protein side chains, and the ease with which radicals can be generated (by radiolysis or photolysis) has made the approach popular with many laboratories. As some side chains are less reactive and thus cannot be probed, additional specific and nonspecific labeling reagents have been introduced to extend the approach. At the same time, advances in liquid chromatography and MS approaches permit an examination of the labeling of individual residues, transforming the approach to high resolution. Lastly, advances in understanding of the chemistry of the approach have led to the determination of absolute protein topologies from HRF data. Overall, the technology can provide precise and accurate measures of side-chain solvent accessibility in a wide range of interesting and useful contexts for the study of protein structure and dynamics in both academia and industry.
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Affiliation(s)
- Janna Kiselar
- Center for Proteomics and Bioinformatics, and Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Mark R. Chance
- Center for Proteomics and Bioinformatics, and Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA
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36
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Chea EE, Jones LM. Modifications generated by fast photochemical oxidation of proteins reflect the native conformations of proteins. Protein Sci 2018; 27:1047-1056. [PMID: 29575296 DOI: 10.1002/pro.3408] [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: 01/25/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 01/08/2023]
Abstract
Hydroxyl radical footprinting (HRF) is a nonspecific protein footprinting method that has been increasingly used in recent years to analyze protein structure. The method oxidatively modifies solvent accessible sites in proteins, which changes upon alterations in the protein, such as ligand binding or a change in conformation. For HRF to provide accurate structural information, the method must probe the native structure of proteins. This requires careful experimental controls since an abundance of oxidative modifications can induce protein unfolding. Fast photochemical oxidation of proteins (FPOP) is a HRF method that generates hydroxyl radicals via photo-dissociation of hydrogen peroxide using an excimer laser. The addition of a radical scavenger to the FPOP reaction reduces the lifetime of the radical, limiting the levels of protein oxidation. A direct assay is needed to ensure FPOP is probing the native conformation of the protein. Here, we report using enzymatic activity as a direct assay to validate that FPOP is probing the native structure of proteins. By measuring the catalytic activity of lysozyme and invertase after FPOP modification, we demonstrate that FPOP does not induce protein unfolding.
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Affiliation(s)
- Emily E Chea
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland, 21201
| | - Lisa M Jones
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland, 21201
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37
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Li KS, Shi L, Gross ML. Mass Spectrometry-Based Fast Photochemical Oxidation of Proteins (FPOP) for Higher Order Structure Characterization. Acc Chem Res 2018; 51:736-744. [PMID: 29450991 DOI: 10.1021/acs.accounts.7b00593] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Assessment of protein structure and interaction is crucial for understanding protein structure/function relationships. Compared to high-resolution structural tools, including X-ray crystallography, nuclear magnetic resonance (NMR), and cryo-EM, and traditional low-resolution methods, such as circular dichroism, UV-vis, and florescence spectroscopy, mass spectrometry (MS)-based protein footprinting affords medium-to-high resolution (i.e., regional and residue-specific insights) by taking advantage of proteomics methods focused on the primary structure. The methodology relies on "painting" the reactive and solvent-exposed amino acid residues with chemical tags and using the pattern of modifications as footprints from analysis by bottom-up MS-based proteomics to deduce protein higher order structures. The outcome can refer to proteins in solution or even in cells and is complementary to those of X-ray crystallography and NMR. It is particularly useful in mapping protein-ligand interfaces and conformational changes resulting from ligand binding, mutation, and aggregation. Fast photochemical oxidation of proteins (FPOP), in its original conception, is a type of hydroxyl-radical-based protein footprinting that utilizes a pulsed KrF laser (248 nm) to trigger hydrolysis of hydrogen peroxide to produce solution hydroxyl radicals, which subsequently modify the protein in situ. The platform is expanding to adopt other reactive species including carbenes. The reactivity of the probe depends on the intrinsic reactivity of the radical with the residue side chain and the solvent accessibility of the residue as a function of the tertiary/quaternary structures. By introducing an appropriate scavenger to compete with hydroxyl radical self-quenching, the lifetime of the primary radicals is remarkably shortened to approximately microsecond. Thus, the sampling time scale of FPOP is much faster than hydrogen-deuterium exchange and other covalent labeling methods relying on nonradical reactions. The short footprinting time scale of FPOP offers two major advantages for protein structure elucidation: (1) it allows the protein to be interrogated in its native or near-native state with minimum structural perturbation; (2) it exhibits high sensitivity toward alterations in protein higher order structures because its sampling time is short with respect to protein conformational changes and dynamic motion. In addition, the covalent and irreversible oxidation by the hydroxyl radical provides more flexibility in the downstream proteomics workflow and MS analysis, permitting high spatial resolution with residue-specific information. Since its invention in 2005 by Hambly and Gross, FPOP has developed from proof-of-concept to a valuable biophysical tool for interrogating protein structure. In this Account, we summarize the principles and experimental design of FPOP that enable its fast labeling and describe the current and unique capabilities of the technique in protein higher order structure elucidation. Application examples include characterization of amyloid β self-assembly, protein-ligand interactions with a special emphasis on epitope mapping for protein therapeutics (e.g., antibody, Fab, and adnectin), protein folding detailed to residue-specific folding kinetics, and protein flexibility/dynamics. Additionally, the utility of FPOP-based oxidative footprinting should grow with our continuing developments of novel reagents (e.g., sulfate radical anion, carbene diradical, and trifluoromethyl radical). These reactive reagents are compatible with the current FPOP platform and offer different reactivity and selectivity toward various types of amino acid residues, providing complementary insights into protein higher order structures for soluble proteins and ultimately for membrane-bound proteins.
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Affiliation(s)
- Ke Sherry Li
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Liuqing Shi
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
| | - Michael L. Gross
- Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States
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38
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Plasma-Generated OH Radical Production for Analyzing Three-Dimensional Structure in Protein Therapeutics. Sci Rep 2017; 7:12946. [PMID: 29021557 PMCID: PMC5636892 DOI: 10.1038/s41598-017-13371-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/21/2017] [Indexed: 11/30/2022] Open
Abstract
Protein three-dimensional structure dynamically changes in solution depending on the presence of ligands and interacting proteins. Methods for detecting these changes in protein conformation include ‘protein footprinting,’ using mass spectrometry. We describe herein a new technique, PLIMB (Plasma Induced Modification of Biomolecules), that generates µs bursts of hydroxyl radicals from water, to measure changes in protein structure via altered solvent accessibility of amino acid side chains. PLIMB was first benchmarked with model compounds, and then applied to a biological problem, i.e., ligand (EGF) induced changes in the conformation of the external (ecto) domain of Epidermal Growth Factor Receptor (EGFR). Regions in which oxidation decreased upon adding EGF fall along the dimerization interface, consistent with models derived from crystal structures. These results demonstrate that plasma-generated hydroxyl radicals from water can be used to map protein conformational changes, and provide a readily accessible means of studying protein structure in solution.
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39
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Ziemianowicz DS, Bomgarden R, Etienne C, Schriemer DC. Amino Acid Insertion Frequencies Arising from Photoproducts Generated Using Aliphatic Diazirines. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2011-2021. [PMID: 28799075 DOI: 10.1007/s13361-017-1730-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/26/2017] [Accepted: 05/29/2017] [Indexed: 06/07/2023]
Abstract
Mapping proteins with chemical reagents and mass spectrometry can generate a measure of accessible surface area, which in turn can be used to support the modeling and refinement of protein structures. Photolytically generated carbenes are a promising class of reagent for this purpose. Substituent effects appear to influence surface mapping properties, allowing for a useful measure of design control. However, to use carbene labeling data in a quantitative manner for modeling activities, we require a better understanding of their inherent amino acid reactivity, so that incorporation data can be normalized. The current study presents an analysis of the amino acid insertion frequency of aliphatic carbenes generated by the photolysis of three different diazirines: 3,3'-azibutyl-1-ammonium, 3,3'-azibutan-1-ol, and 4,4'-azipentan-1-oate. Leveraging an improved photolysis system for single-shot labeling of sub-microliter frozen samples, we used EThCD to localize insertion products in a large population of labeled peptides. Counting statistics were drawn from data-dependent LC-MS2 experiments and used to estimate the frequencies of insertion as a function of amino acid. We observed labeling of all 20 amino acids over a remarkably narrow range of insertion frequencies. However, the nature of the substituent could influence relative insertion frequencies, within a general preference for larger polar amino acids. We confirm a large (6-fold) increase in labeling yield when carbenes were photogenerated in the solid phase (77 K) relative to the liquid phase (293 K), and we suggest that carbene labeling should always be conducted in the frozen state to avoid information loss in surface mapping experiments. Graphical Abstract ᅟ.
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Affiliation(s)
- Daniel S Ziemianowicz
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Ryan Bomgarden
- Thermo Fisher Scientific, 3747 N. Meridian Rd., Rockford, IL, 61101, USA
| | - Chris Etienne
- Thermo Fisher Scientific, 3747 N. Meridian Rd., Rockford, IL, 61101, USA
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, T2N 4N1, Canada.
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40
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Li KS, Chen G, Mo J, Huang RYC, Deyanova EG, Beno BR, O’Neil SR, Tymiak AA, Gross ML. Orthogonal Mass Spectrometry-Based Footprinting for Epitope Mapping and Structural Characterization: The IL-6 Receptor upon Binding of Protein Therapeutics. Anal Chem 2017; 89:7742-7749. [PMID: 28621526 PMCID: PMC5549780 DOI: 10.1021/acs.analchem.7b01748] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Higher-order structure (HOS) is a crucial determinant for the biological functions and quality attributes of protein therapeutics. Mass spectrometry (MS)-based protein footprinting approaches play an important role in elucidating the relationship between protein biophysical properties and structure. Here, we describe the use of a combined method including hydrogen-deuterium exchange (HDX), fast photochemical oxidation of proteins (FPOP), and site-specific carboxyl group footprinting to investigate the HOS of protein and protein complexes. The work focuses on implementing complementary solution-phase footprinting approaches that differ in time scale, specificity for protein residue side chains vs backbone as well as selectivity for different residue types to map integratively the epitope of human interleukin-6 receptor (IL-6R) for two adnectins with distinct affinities (Kd, Adnectin1 ∼ 6.2 pM vs Kd, Adnectin2 ∼ 46 nM). Furthermore, the study evaluates the resultant conformation/dynamic change of IL-6R. The suggested epitope, which is conserved for adnectin1 and adnectin2 binding, is a flexible loop that connects two β-strands in the cytokine-binding domain (DII) of IL-6R. We also found that adnectin1, the more strongly binding ligand, induces structural perturbations on two unstructured loops that are distally located beyond the epitope. Those changes are either attenuated or not detected for the case of adnectin2 binding. In addition to providing credibility in epitope determination, utilization of those combined approaches reveals the structural effects that can differentiate protein therapeutics with apparently similar biophysical properties.
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Affiliation(s)
- Ke Sherry Li
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Guodong Chen
- Bioanalytical and Discovery Analytical Sciences, Pharmaceutical Candidate Optimization, Research and Development, Bristol-Myers Squibb, Princeton, NJ 08540, USA
| | - Jingjie Mo
- Bioanalytical and Discovery Analytical Sciences, Pharmaceutical Candidate Optimization, Research and Development, Bristol-Myers Squibb, Princeton, NJ 08540, USA
| | - Richard Y-C Huang
- Bioanalytical and Discovery Analytical Sciences, Pharmaceutical Candidate Optimization, Research and Development, Bristol-Myers Squibb, Princeton, NJ 08540, USA
| | - Ekaterina G. Deyanova
- Bioanalytical and Discovery Analytical Sciences, Pharmaceutical Candidate Optimization, Research and Development, Bristol-Myers Squibb, Princeton, NJ 08540, USA
| | - Brett R. Beno
- Molecular Discovery Technologies, Research and Development, Bristol-Myers Squibb, Wallingford, CT 06492, and Waltham, MA 02453, USA
| | - Steve R. O’Neil
- Molecular Discovery Technologies, Research and Development, Bristol-Myers Squibb, Wallingford, CT 06492, and Waltham, MA 02453, USA
| | - Adrienne A. Tymiak
- Bioanalytical and Discovery Analytical Sciences, Pharmaceutical Candidate Optimization, Research and Development, Bristol-Myers Squibb, Princeton, NJ 08540, USA
| | - Michael L. Gross
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
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