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Larsen DN, Kaczmarek JZ, Palarasah Y, Graversen JH, Højrup P. Epitope mapping of SARS-CoV-2 RBDs by hydroxyl radical protein footprinting reveals the importance of including negative antibody controls. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2024; 1872:141011. [PMID: 38499233 DOI: 10.1016/j.bbapap.2024.141011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 03/01/2024] [Accepted: 03/11/2024] [Indexed: 03/20/2024]
Abstract
Understanding protein-protein interactions is crucial for drug design and investigating biological processes. Various techniques, such as CryoEM, X-ray spectroscopy, linear epitope mapping, and mass spectrometry-based methods, can be employed to map binding regions on proteins. Commonly used mass spectrometry-based techniques are cross-linking and hydrogen‑deuterium exchange (HDX). Another approach, hydroxyl radical protein footprinting (HRPF), identifies binding residues on proteins but faces challenges due to high initial costs and complex setups. This study introduces a generally applicable method using Fenton chemistry for epitope mapping in a standard mass spectrometry laboratory. It emphasizes the importance of controls, particularly the inclusion of a negative antibody control, not widely utilized in HRPF epitope mapping. Quantification by TMT labelling is introduced to reduce false positives, enabling direct comparison between sample conditions and biological triplicates. Additionally, six technical replicates were incorporated to enhance the depth of analysis. Observations on the receptor-binding domain (RBD) of SARS-CoV-2 Spike Protein, Alpha and Delta variants, revealed both binding and opening regions. Significantly changed peptides upon mixing with a negative control antibody suggested structural alterations or nonspecific binding induced by the antibody alone. Integration of negative control antibody experiments and high overlap between biological triplicates led to the exclusion of 40% of significantly changed regions. The final identified binding region correlated with existing literature on neutralizing antibodies against RBD. The presented method offers a straightforward implementation for HRPF analysis in a generic mass spectrometry-based laboratory. Enhanced data reliability was achieved through increased technical and biological replicates alongside negative antibody controls.
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Affiliation(s)
- Daniel Nyberg Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark; Ovodan Biotech A/S, Havnegade 36, DK-5000 Odense, Denmark
| | | | - Yaseelan Palarasah
- Department of Inflammation, Institute of Molecular Medicine, Faculty of Health and Medical Sciences, University of Southern Denmark, Odense, Denmark
| | - Jonas Heilskov Graversen
- Department of Inflammation, Institute of Molecular Medicine, Faculty of Health and Medical Sciences, University of Southern Denmark, Odense, Denmark
| | - Peter Højrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark; Ovodan Biotech A/S, Havnegade 36, DK-5000 Odense, Denmark.
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2
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Punzalan C, Wang L, Bajrami B, Yao X. Measurement and utilization of the proteomic reactivity by mass spectrometry. MASS SPECTROMETRY REVIEWS 2024; 43:166-192. [PMID: 36924435 DOI: 10.1002/mas.21837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 02/17/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Chemical proteomics, which involves studying the covalent modifications of proteins by small molecules, has significantly contributed to our understanding of protein function and has become an essential tool in drug discovery. Mass spectrometry (MS) is the primary method for identifying and quantifying protein-small molecule adducts. In this review, we discuss various methods for measuring proteomic reactivity using MS and covalent proteomics probes that engage through reactivity-driven and proximity-driven mechanisms. We highlight the applications of these methods and probes in live-cell measurements, drug target identification and validation, and characterizing protein-small molecule interactions. We conclude the review with current developments and future opportunities in the field, providing our perspectives on analytical considerations for MS-based analysis of the proteomic reactivity landscape.
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Affiliation(s)
- Clodette Punzalan
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
| | - Lei Wang
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
- AD Bio US, Takeda, Lexington, Massachusetts, 02421, USA
| | - Bekim Bajrami
- Chemical Biology & Proteomics, Biogen, Cambridge, Massachusetts, USA
| | - Xudong Yao
- Department of Chemistry, University of Connecticut, Storrs, Connecticut, USA
- Institute for Systems Biology, University of Connecticut, Storrs, Connecticut, USA
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3
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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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Pan X, Vachet RW. MEMBRANE PROTEIN STRUCTURES AND INTERACTIONS FROM COVALENT LABELING COUPLED WITH MASS SPECTROMETRY. MASS SPECTROMETRY REVIEWS 2022; 41:51-69. [PMID: 33145813 PMCID: PMC8093322 DOI: 10.1002/mas.21667] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 05/31/2023]
Abstract
Membrane proteins are incredibly important biomolecules because they mediate interactions between a cell's external and internal environment. Obtaining information about membrane protein structure and interactions is thus important for understanding these essential biomolecules. Compared with the analyses of water-soluble proteins, the structural analysis of membrane proteins is more challenging owing to their unique chemical properties and the presence of lipid components that are necessary to solubilize them. The combination of covalent labeling (CL) and mass spectrometry (MS) has recently been applied with great success to study membrane protein structure and interactions. These studies have demonstrated the many advantages that CL-MS methods have over other traditional biophysical techniques. In this review, we discuss both amino acid-specific and non-specific labeling approaches and the special considerations needed to address the unique challenges associated with interrogating membrane proteins. This review highlights the aspects of this approach that require special care to be applied correctly and provides a comprehensive review of the membrane protein systems that have been studied by CL-MS. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.
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Zhou F, Yang Y, Chemuru S, Cui W, Liu S, Gross M, Li W. Footprinting Mass Spectrometry of Membrane Proteins: Ferroportin Reconstituted in Saposin A Picodiscs. Anal Chem 2021; 93:11370-11378. [PMID: 34383472 DOI: 10.1021/acs.analchem.1c02325] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Membrane proteins participate in a broad range of cellular processes and represent more than 60% of drug targets. One approach to their structural analyses is mass spectrometry (MS)-based footprinting including hydrogen/deuterium exchange (HDX), fast photochemical oxidation of proteins (FPOP), and residue-specific chemical modification. Studying membrane proteins usually requires their isolation from the native lipid environment, after which they often become unstable. To overcome this problem, we are pursuing a novel methodology of incorporating membrane proteins into saposin A picodiscs for MS footprinting. We apply different footprinting approaches to a model membrane protein, mouse ferroportin, in picodiscs and achieve high coverage that enables the analysis of the ferroportin structure. FPOP footprinting shows extensive labeling of the extramembrane regions of ferroportin and protection at its transmembrane regions, suggesting that the membrane folding of ferroportin is maintained throughout the labeling process. In contrast, an amphipathic reagent, N-ethylmaleimide (NEM), efficiently labels cysteine residues in both extramembrane and transmembrane regions, thereby affording complementary footprinting coverage. Finally, optimization of sample treatment gives a peptic-map of ferroportin in picodiscs with 92% sequence coverage, setting the stage for HDX. These results, taken together, show that picodiscs are a new platform broadly applicable to mass spectrometry studies of membrane proteins.
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Affiliation(s)
- Fengbo Zhou
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Yihu Yang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Saketh Chemuru
- Department of Chemistry, Washington University, St. Louis, Missouri 63110, United States
| | - Weidong Cui
- Department of Chemistry, Washington University, St. Louis, Missouri 63110, United States
| | - Shixuan Liu
- Department of Chemistry, Washington University, St. Louis, Missouri 63110, United States
| | - Michael Gross
- Department of Chemistry, Washington University, St. Louis, Missouri 63110, United States
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
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Johnson DT, Di Stefano LH, Jones LM. Fast photochemical oxidation of proteins (FPOP): A powerful mass spectrometry-based structural proteomics tool. J Biol Chem 2019; 294:11969-11979. [PMID: 31262727 DOI: 10.1074/jbc.rev119.006218] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fast photochemical oxidation of proteins (FPOP) is a MS-based method that has proved useful in studies of protein structures, interactions, conformations, and protein folding. The success of this method relies on the irreversible labeling of solvent-exposed amino acid side chains by hydroxyl radicals. FPOP generates these radicals through laser-induced photolysis of hydrogen peroxide. The data obtained provide residue-level resolution of protein structures and interactions on the microsecond timescale, enabling investigations of fast processes such as protein folding and weak protein-protein interactions. An extensive comparison between FPOP and other footprinting techniques gives insight on their complementarity as well as the robustness of FPOP to provide unique structural information once unattainable. The versatility of this method is evidenced by both the heterogeneity of samples that can be analyzed by FPOP and the myriad of applications for which the method has been successfully used: from proteins of varying size to intact cells. This review discusses the wide applications of this technique and highlights its high potential. Applications including, but not limited to, protein folding, membrane proteins, structure elucidation, and epitope mapping are showcased. Furthermore, the use of FPOP has been extended to probing proteins in cells and in vivo These promising developments are also presented herein.
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Affiliation(s)
- Danté T Johnson
- Department of Pharmaceutical Sciences, University of Maryland, Baltimore, Maryland 21201
| | - Luciano H Di Stefano
- 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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7
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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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8
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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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Zhu Y, Serra A, Guo T, Park JE, Zhong Q, Sze SK. Application of Nanosecond Laser Photolysis Protein Footprinting to Study EGFR Activation by EGF in Cells. J Proteome Res 2017; 16:2282-2293. [DOI: 10.1021/acs.jproteome.7b00154] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Yi Zhu
- School
of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore
| | - Aida Serra
- School
of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore
| | - Tiannan Guo
- School
of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore
| | - Jung Eun Park
- School
of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore
| | - Qing Zhong
- Department
of Pathology and Molecular Pathology, University Hospital Zürich, Zürich, Switzerland
| | - Siu Kwan Sze
- School
of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive 637551, Singapore
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10
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Rational design and functional evolution of targeted peptides for bioanalytical applications. Sci China Chem 2016. [DOI: 10.1007/s11426-016-0186-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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11
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Vahidi S, Konermann L. Probing the Time Scale of FPOP (Fast Photochemical Oxidation of Proteins): Radical Reactions Extend Over Tens of Milliseconds. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1156-64. [PMID: 27067899 DOI: 10.1007/s13361-016-1389-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/09/2016] [Accepted: 03/14/2016] [Indexed: 05/11/2023]
Abstract
Hydroxyl radical (⋅OH) labeling with mass spectrometry detection reports on protein conformations and interactions. Fast photochemical oxidation of proteins (FPOP) involves ⋅OH production via H2O2 photolysis by UV laser pulses inside a flow tube. The experiments are conducted in the presence of a scavenger (usually glutamine) that shortens the ⋅OH lifetime. The literature claims that FPOP takes place within 1 μs. This ultrafast time scale implies that FPOP should be immune to labeling-induced artifacts that may be encountered with other techniques. Surprisingly, the FPOP time scale has never been validated in direct kinetic measurements. Here we employ flash photolysis for probing oxidation processes under typical FPOP conditions. Bleaching of the reporter dye cyanine-5 (Cy5) served as readout of the time-dependent radical milieu. Surprisingly, Cy5 oxidation extends over tens of milliseconds. This time range is four orders of magnitude longer than expected from the FPOP literature. We demonstrate that the glutamine scavenger generates metastable secondary radicals in the FPOP solution, and that these radicals lengthen the time frame of Cy5 oxidation. Cy5 and similar dyes are widely used for monitoring the radical dose experienced by proteins in solution. The measured Cy5 kinetics thus strongly suggest that protein oxidation in FPOP extends over a much longer time window than previously thought (i.e., many milliseconds instead of one microsecond). The optical approach developed here should be suitable for assessing the performance of future FPOP-like techniques with improved temporal labeling characteristics. Graphical Abstract ᅟ.
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Affiliation(s)
- Siavash Vahidi
- 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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