1
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Wagner WJ, Moyle AB, Wagner ND, Rempel DL, Gross ML. Evaluating Chemical Footprinting-Induced Perturbation of Protein Higher Order Structure. Anal Chem 2024; 96:9693-9703. [PMID: 38815160 PMCID: PMC11238718 DOI: 10.1021/acs.analchem.4c01735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Specific amino acid footprinting mass spectrometry (MS) is an increasingly utilized method for elucidating protein higher order structure (HOS). It does this by adding to certain amino acid residues a mass tag, whose reaction extent depends on solvent accessibility and microenvironment of the protein. Unlike reactive free radicals and carbenes, these specific footprinters react slower than protein unfolding. Thus, their footprinting, under certain conditions, provokes structural changes to the protein, leading to labeling on non-native structures. It is critical to establish conditions (i.e., reagent concentrations, time of reaction) to ensure that the structure of the protein following footprinting remains native. Here, we compare the efficacy of five methods in assessing protein HOS following footprinting at the intact protein level and then further localize the perturbation at the peptide level. Three are MS-based methods that provide dose-response plot analysis, evaluation of Poisson distributions of precursor and products, and determination of the average number of modifications. These MS-based methods reliably and effectively indicate HOS perturbation at the intact protein level, whereas spectroscopic methods (circular dichroism (CD) and dynamic light scattering (DLS)) are less sensitive in monitoring subtle HOS perturbation caused by footprinting. Evaluation of HOS at the peptide level indicates regions that are sensitive to localized perturbations. Peptide-level analysis also provides higher resolution of the HOS perturbation, and we recommend using it for future footprinting studies. Overall, this work shows conclusive evidence for HOS perturbation caused by footprinting. Implementation of quality control workflows can identify conditions to avoid the perturbation, for footprinting, allowing accurate and reliable identification of protein structural changes that accompany, for example, ligand interactions, mutations, and changes in solution environment.
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Affiliation(s)
- Wesley J Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Austin B Moyle
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Nicole D Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Don L Rempel
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 United States
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2
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Jiang R, Rempel DL, Gross ML. Toward a MALDI in-source decay (ISD) method for top-down analysis of protein footprinting. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2023; 29:292-302. [PMID: 37750197 PMCID: PMC11092977 DOI: 10.1177/14690667231202695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Irreversible protein footprinting is a mass spectrometry-based approach in which solvent-accessible sites of a protein are modified to assess high-order protein structure. Structural insights can be gained by determining the position and extents of modification. The usual approach to obtain the "footprint" is to analyze the protein through bottom-up LC-MS/MS. In this approach, the proteins are digested to yield a mixture of peptides that are then separated by LC before locating the modification sites by MS/MS. This process consumes substantial amounts of time and is difficult to accelerate for applications that require quick and high-throughput analysis. Here, we describe employing matrix-assisted laser desorption/ionization (MALDI) in-source decay (ISD) to analyze a footprinted small test protein (ubiquitin) via a top-down approach. Matrix-assisted laser desorption/ionization is easily adapted for high-throughput analysis, and top-down strategies can avoid lengthy proteolysis and LC separation. We optimized the method with model peptides and then demonstrated its feasibility on ubiquitin submitted to two types of footprinting. We found that MALDI ISD can produce a comprehensive set of fragment ions for small proteins, affording footprinting information in a fast manner and giving results that agree with the established methods, and serve as a rough measure of protein solvent accessibility. To assist in the implementation of the MALDI approach, we developed a method of processing top-down ISD data.
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Affiliation(s)
- Ruidong Jiang
- Department of Chemistry, Washington University in St Louis, St Louis, MO, USA
| | - Don L Rempel
- Department of Chemistry, Washington University in St Louis, St Louis, MO, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St Louis, St Louis, MO, USA
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3
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Farquhar ER, Vijayalakshmi K, Jain R, Wang B, Kiselar J, Chance MR. Intact mass spectrometry screening to optimize hydroxyl radical dose for protein footprinting. Biochem Biophys Res Commun 2023; 671:343-349. [PMID: 37329657 PMCID: PMC10510565 DOI: 10.1016/j.bbrc.2023.06.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 06/05/2023] [Indexed: 06/19/2023]
Abstract
Hydroxyl radical protein footprinting (HRPF) using synchrotron radiation is a well-validated method to assess protein structure in the native solution state. In this method, X-ray radiolysis of water generates hydroxyl radicals that can react with solvent accessible side chains of proteins, with mass spectrometry used to detect the resulting labeled products. An ideal footprinting dose provides sufficient labeling to measure the structure but not so much as to influence the results. The optimization of hydroxyl radical dose is typically performed using an indirect Alexa488 fluorescence assay sensitive to hydroxyl radical concentration, but full evaluation of the experiment's outcome relies upon bottom-up liquid chromatography mass spectrometry (LC-MS) measurements to directly determine sites and extent of oxidative labeling at the peptide and protein level. A direct evaluation of the extent of labeling to provide direct and absolute measurements of dose and "safe" dose ranges in terms of, for example, average numbers of labels per protein, would provide immediate feedback on experimental outcomes prior to embarking on detailed LC-MS analyses. To this end, we describe an approach to integrate intact MS screening of labeled samples immediately following exposure, along with metrics to quantify the extent of observed labeling from the intact mass spectra. Intact MS results on the model protein lysozyme were evaluated in the context of Alexa488 assay results and a bottom-up LC-MS analysis of the same samples. This approach provides a basis for placing delivered hydroxyl radical dose metrics on firmer technical grounds for synchrotron X-ray footprinting of proteins, with explicit parameters to increase the likelihood of a productive experimental outcome. Further, the method directs approaches to provide absolute and direct dosimetry for all types of labeling for protein footprinting.
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Affiliation(s)
- Erik R Farquhar
- Center for Synchrotron Biosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; Department of Nutrition, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA.
| | - Kanchustambham Vijayalakshmi
- Center for Synchrotron Biosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; Department of Nutrition, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Rohit Jain
- Center for Synchrotron Biosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; Department of Nutrition, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA; Center for Proteomics and Bioinformatics, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Benlian Wang
- Department of Nutrition, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA; Center for Proteomics and Bioinformatics, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Janna Kiselar
- Department of Nutrition, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA; Center for Proteomics and Bioinformatics, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Mark R Chance
- Center for Synchrotron Biosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; Department of Nutrition, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA; Center for Proteomics and Bioinformatics, Case Western Reserve University, School of Medicine, 10900 Euclid Ave., Cleveland, OH, 44106, USA.
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4
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Moyle AB, Wagner ND, Wagner WJ, Cheng M, Gross ML. Workflow for Validating Specific Amino Acid Footprinting Reagents for Protein Higher Order Structure Elucidation. Anal Chem 2023; 95:10119-10126. [PMID: 37351860 PMCID: PMC10476636 DOI: 10.1021/acs.analchem.3c01919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Protein footprinting mass spectrometry probes protein higher order structure and dynamics by labeling amino acid side-chains or backbone amides as a function of solvent accessibility. One category of footprinting uses residue-specific, irreversible covalent modifications, affording flexibility of sample processing for bottom-up analysis. Although several specific amino acid footprinting technologies are becoming established in structural proteomics, there remains a need to assess fundamental properties of new reagents before their application. Often, footprinting reagents are applied to complex or novel protein systems soon after their discovery and sometimes without a thorough investigation of potential downsides of the reagent. In this work, we assemble and test a validation workflow that utilizes cyclic peptides and a model protein to characterize benzoyl fluoride, a recently published, next-generation nucleophile footprinter. The workflow includes the characterization of potential side-chain reactive groups, reaction "quench" efficacies, reagent considerations and caveats (e.g., buffer pH), residue-specific kinetics compared to those of established reagents, and protein-wide characterization of modification sites with considerations for proteolysis. The proposed workflow serves as a starting point for improved footprinting reagent discovery, validation, and introduction, the aspects of which we recommend before applying to unknown protein systems.
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Affiliation(s)
- Austin B. Moyle
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Nicole D. Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Wesley J. Wagner
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Ming Cheng
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
| | - Michael L. Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130 United States
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5
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Yang HC, Li W, Sun J, Gross ML. Advances in Mass Spectrometry on Membrane Proteins. MEMBRANES 2023; 13:457. [PMID: 37233518 PMCID: PMC10220746 DOI: 10.3390/membranes13050457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/15/2023] [Accepted: 04/21/2023] [Indexed: 05/27/2023]
Abstract
Understanding the higher-order structure of membrane proteins (MPs), which are vital for numerous biological processes, is crucial for comprehending their function. Although several biophysical approaches have been used to study the structure of MPs, limitations exist owing to the proteins' dynamic nature and heterogeneity. Mass spectrometry (MS) is emerging as a powerful tool for investigating membrane protein structure and dynamics. Studying MPs using MS, however, must meet several challenges including the lack of stability and solubility of MPs, the complexity of the protein-membrane system, and the difficulty of digestion and detection. To meet these challenges, recent advances in MS have engendered opportunities in resolving the dynamics and structures of MP. This article reviews achievements over the past few years that enable the study of MPs by MS. We first introduce recent advances in hydrogen deuterium exchange and native mass spectrometry for MPs and then focus on those footprinting methods that report on protein structure.
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Affiliation(s)
- Hsin-Chieh Yang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Weikai Li
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA;
| | - Jie Sun
- 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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6
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Anderson AJ, Seebald LM, Arbour CA, Imperiali B. Probing Monotopic Phosphoglycosyl Transferases from Complex Cellular Milieu. ACS Chem Biol 2022; 17:3191-3197. [PMID: 36346917 PMCID: PMC9703085 DOI: 10.1021/acschembio.2c00648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Monotopic phosphoglycosyl transferase enzymes (monoPGTs) initiate the assembly of prokaryotic glycoconjugates essential for bacterial survival and proliferation. MonoPGTs belong to an expansive superfamily with a diverse and richly annotated sequence space; however, the biochemical roles of most monoPGTs in glycoconjugate biosynthesis pathways remain elusive. To better understand these critical enzymes, we have implemented activity-based protein profiling (ABPP) probes as protein-centric, membrane protein compatible tools that lay the groundwork for understanding the activity and regulation of the monoPGT superfamily from a cellular proteome. With straightforward gel-based readouts, we demonstrate robust, covalent labeling at the active site of various representative monoPGTs from cell membrane fractions using 3-phenyl-2H-azirine probes.
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Affiliation(s)
- Alyssa J. Anderson
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Leah M. Seebald
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Christine A. Arbour
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Barbara Imperiali
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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7
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Wagner ND, Moyle AB, Pabon JPR, Gross ML. Automated Specific Amino Acid Footprinting Mass Spectrometry: Repurposing an HDX Platform for Determining Reagent Feasibility. Anal Chem 2022; 94:10314-10319. [PMID: 35830607 PMCID: PMC10482561 DOI: 10.1021/acs.analchem.2c02073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein footprinting is a mass spectrometry (MS)-based approach to measure protein conformational changes. One approach, specific amino acid labeling, imparts often an irreversible modification to protein side chains but requires careful selection of the reactive reagent and often time-consuming optimization of experimental parameters prior to submission to bottom-up MS analysis. In this work, we repurpose a hydrogen-deuterium exchange MS (HDX-MS) LEAP HDX system for automated specific amino acid footprinting MS, demonstrating its efficacy in reaction optimization and monitoring applicability to specific ligand binding systems. We screened reagent conditions for two model ligand-binding systems and demonstrate the method's efficacy for measuring differences induced by ligand binding. Our proof-of-concept experiments provide a platform for rapidly screening specific amino acid reagents and reaction conditions for protein systems to be studied by footprinting.
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Affiliation(s)
- Nicole D. Wagner
- Washington University in St. Louis, Department of Chemistry, St. Louis, MO 63130
| | - Austin B. Moyle
- Washington University in St. Louis, Department of Chemistry, St. Louis, MO 63130
| | - Juan P. Rincon Pabon
- Washington University in St. Louis, Department of Chemistry, St. Louis, MO 63130
| | - Michael L. Gross
- Washington University in St. Louis, Department of Chemistry, St. Louis, MO 63130
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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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Goodwin JM, Walkup WG, Hooper K, Li T, Kishi-Itakura C, Ng A, Lehmberg T, Jha A, Kommineni S, Fletcher K, Garcia-Fortanet J, Fan Y, Tang Q, Wei M, Agrawal A, Budhe SR, Rouduri SR, Baird D, Saunders J, Kiselar J, Chance MR, Ballabio A, Appleton BA, Brumell JH, Florey O, Murphy LO. GABARAP sequesters the FLCN-FNIP tumor suppressor complex to couple autophagy with lysosomal biogenesis. SCIENCE ADVANCES 2021; 7:eabj2485. [PMID: 34597140 PMCID: PMC10938568 DOI: 10.1126/sciadv.abj2485] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/11/2021] [Indexed: 05/28/2023]
Abstract
Adaptive changes in lysosomal capacity are driven by the transcription factors TFEB and TFE3 in response to increased autophagic flux and endolysosomal stress, yet the molecular details of their activation are unclear. LC3 and GABARAP members of the ATG8 protein family are required for selective autophagy and sensing perturbation within the endolysosomal system. Here, we show that during the conjugation of ATG8 to single membranes (CASM), Parkin-dependent mitophagy, and Salmonella-induced xenophagy, the membrane conjugation of GABARAP, but not LC3, is required for activation of TFEB/TFE3 to control lysosomal capacity. GABARAP directly binds to a previously unidentified LC3-interacting motif (LIR) in the FLCN/FNIP tumor suppressor complex and mediates sequestration to GABARAP-conjugated membrane compartments. This disrupts FLCN/FNIP GAP function toward RagC/D, resulting in impaired substrate-specific mTOR-dependent phosphorylation of TFEB. Thus, the GABARAP-FLCN/FNIP-TFEB axis serves as a molecular sensor that coordinates lysosomal homeostasis with perturbations and cargo flux within the autophagy-lysosomal network.
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Affiliation(s)
| | - Ward G. Walkup
- Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA
| | - Kirsty Hooper
- Signalling Programme, Babraham Institute, Cambridge, UK
| | - Taoyingnan Li
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | | | - Aylwin Ng
- Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA
| | | | - Archana Jha
- Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA
| | | | | | | | | | | | | | - Asmita Agrawal
- Sai Life Sciences Limited, Pune 411057, Maharashtra, India
| | - Sagar R. Budhe
- Sai Life Sciences Limited, Pune 411057, Maharashtra, India
| | | | - Dan Baird
- Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA
| | - Jeff Saunders
- Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA
| | | | - Mark R. Chance
- NEO Proteomics Inc., Cleveland, OH 44106, USA
- School of Medicine, Case Western Reserve University, Cleveland, OH 44016, USA
| | - Andrea Ballabio
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
- Medical Genetics Unit, Department of Medical and Translational Science, Federico II University, Naples, Italy
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
- SSM School for Advanced Studies, Federico II University, Naples, Italy
| | | | - John H. Brumell
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
- SickKids IBD Centre, Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Oliver Florey
- Signalling Programme, Babraham Institute, Cambridge, UK
| | - Leon O. Murphy
- Casma Therapeutics, 400 Technology Sq, Cambridge, MA 02139, USA
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10
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Xia N, Lu XX, Zheng Z, Mu DD, Zhong XY, Luo SZ, Zhao YY. Study on preparation of acylated soy protein and stability of emulsion. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2021; 101:4959-4968. [PMID: 33543501 DOI: 10.1002/jsfa.11139] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/08/2021] [Accepted: 02/04/2021] [Indexed: 05/24/2023]
Abstract
BACKGROUND Protein can be used as an emulsifier to improve emulsion stability at the interface of water-in-oil emulsion. However, natural soybean protein isolate (SPI) does not meet the high demands as an emulsifier in the food industry. The effect of acylation modification by ethylenediaminetetraacetic dianhydride (EDTAD; 0-300 g kg-1 ) on the physicochemical properties of SPI was studied. RESULTS The results of the Fourier transform infrared spectra analyses showed that carboxyl groups were introduced into the SPI structure by the EDTAD treatment. The carboxyl concentration of SPI was increased by 30-74.07% with an increase in EDTAD addition from 50 to 300 g kg-1 . When 150 g kg-1 EDTAD was added, the surface hydrophobicity, the emulsifying activity, and the absolute value of the zeta potential were increased by 213%, 120%, and 68% respectively, and the particle size decreased to 247 nm. The droplet size of emulsion decreased to 10 μm when pH was 6. At the same concentration of SPI and pH, the absolute value of zeta potential of the emulsion was biggest. A comparison of the emulsions during storage showed the improvement of emulsion stability was related to the increase in the zeta potential and the decrease in the average particle size. The experimental group showed no destabilization on day 21, and no obvious aggregation phenomenon was observed. CONCLUSION Acylation modification by EDTAD changed the emulsifying properties of SPI and enhanced the stability of the SPI emulsion. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Nan Xia
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
| | - Xing-Xing Lu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
| | - Zhi Zheng
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
| | - Dong-Dong Mu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
| | - Xi-Yang Zhong
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
| | - Shui-Zhong Luo
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
| | - Yan-Yan Zhao
- School of Food and Biological Engineering, Hefei University of Technology, Hefei, China
- Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China
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11
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Huang RYC, Wang Y, Jhatakia AD, Deng AX, Bee C, Deshpande S, Rangan VS, Bezman N, Gudmundsson O, Chen G. Higher-Order Structure Characterization of NKG2A/CD94 Protein Complex and Anti-NKG2A Antibody Binding Epitopes by Mass Spectrometry-Based Protein Footprinting Strategies. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1567-1574. [PMID: 33415981 DOI: 10.1021/jasms.0c00399] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
NK group 2 member A (NKG2A), an immune checkpoint inhibitor, is an emerging therapeutic target in immuno-oncology. NKG2A forms a heterodimer with CD94 on the cell surface of NK and a subset of T cells and recognizes the nonclassical human leukocyte antigen (HLA-E) in humans. Therapeutic blocking antibodies that block the ligation between HLA-E and NKG2A/CD94 have been shown to enhance antitumor immunity in mice and humans. In this study, we illustrate the practical utilities of mass spectrometry (MS)-based protein footprinting in areas from reagent characterization to antibody epitope mapping. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) in the higher-order structure characterization of NKG2A in complex with CD94 provides novel insights into the conformational dynamics of NKG2A/CD94 heterodimer. To fully understand antibody/target interactions, we employed complementary protein footprinting methods, including HDX-MS and fast photochemical oxidation of proteins (FPOP)-MS, to determine the binding epitopes of therapeutic monoclonal antibodies targeting NKG2A. Such a combination approach provides molecular insights into the binding mechanisms of antibodies to NKG2A with high specificity, demonstrating the blockade of NKG2A/HLA-E interaction.
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Affiliation(s)
- Richard Y-C Huang
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey United States
| | - Yun Wang
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey United States
| | - Amy D Jhatakia
- Discovery Biology, Research and Early Development, Bristol Myers Squibb Company, Redwood City, California United States
| | - Andy X Deng
- Discovery Biotherapeutics, Research and Early Development, Bristol Myers Squibb Company, Redwood City, California United States
| | - Christine Bee
- Discovery Biotherapeutics, Research and Early Development, Bristol Myers Squibb Company, Redwood City, California United States
| | - Shrikant Deshpande
- Discovery Biotherapeutics, Research and Early Development, Bristol Myers Squibb Company, Redwood City, California United States
| | - Vangipuram S Rangan
- Discovery Biotherapeutics, Research and Early Development, Bristol Myers Squibb Company, Redwood City, California United States
| | - Natalie Bezman
- Discovery Biology, Research and Early Development, Bristol Myers Squibb Company, Redwood City, California United States
| | - Olafur Gudmundsson
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey United States
| | - Guodong Chen
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey United States
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12
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McKenzie-Coe A, Shortt R, Jones LM. THE MAKING OF A FOOTPRINT IN PROTEIN FOOTPRINTING: A REVIEW IN HONOR OF MICHAEL L. GROSS. MASS SPECTROMETRY REVIEWS 2021; 40:177-200. [PMID: 32400038 PMCID: PMC7849054 DOI: 10.1002/mas.21632] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Within the past decade protein footprinting in conjunction with mass spectrometry has become a powerful and versatile means to unravel the higher order structure of proteins. Footprinting-based approaches has demonstrated the capacity to inform on interaction sites and dynamic regions that participate in conformational changes. These findings when set in a biological perspective inform on protein folding/unfolding, protein-protein interactions, and protein-ligand interactions. In this review, we will look at the contribution of Dr. Michael L. Gross to protein footprinting approaches such as hydrogen deuterium exchange mass spectrometry and hydroxyl radical protein footprinting. This review details the development of novel footprinting methods as well as their applications to study higher order protein structure. © 2020 The Authors. Mass Spectrometry Reviews published by John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Alan McKenzie-Coe
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
| | - Raquel Shortt
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
| | - Lisa M Jones
- Department of Pharmaceutical Sciences, University of Maryland Baltimore, Baltimore, Maryland, 21201
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13
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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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14
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Huang RYC, Wang F, Wheeler M, Wang Y, Langish R, Chau B, Dong J, Morishige W, Bezman N, Strop P, Rajpal A, Gudmundsson O, Chen G. Integrated Approach for Characterizing Bispecific Antibody/Antigens Complexes and Mapping Binding Epitopes with SEC/MALS, Native Mass Spectrometry, and Protein Footprinting. Anal Chem 2020; 92:10709-10716. [PMID: 32639723 DOI: 10.1021/acs.analchem.0c01876] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Bispecific antibodies (BsAbs), with a unique mechanism of recognizing two different epitopes or antigens, have shown potential in various therapeutic areas. Molecular characterization of BsAbs' epitopes not only allows for detailed understanding of their mechanism of actions but also guides the design and selection of drug candidate molecules. In this study, we illustrate the practical utility of an integrated approach, including size exclusion chromatography with multiangle light scattering and native mass spectrometry (MS) for the biophysical characterization of complex formation of a BsAb with two target antigens, cluster of differentiation 3 (CD3) and B-cell maturation antigen (BCMA). MS-based protein footprinting strategies, including hydrogen/deuterium exchange MS, fast photochemical oxidation of proteins, and carboxyl group footprinting with glycine ethyl ester, were further applied to determine BsAb's binding epitopes. This combination approach provides molecular details on the binding mechanisms of BsAb to the two distinct antigens with rapid output and high resolution.
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Affiliation(s)
- Richard Y-C Huang
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey 08540, United States
| | - Feng Wang
- Protein Engineering, Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Matthew Wheeler
- Discovery Biology, Research and Early Development, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Yun Wang
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey 08540, United States
| | - Robert Langish
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey 08540, United States
| | - Bryant Chau
- Protein Engineering, Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Jia Dong
- Protein Engineering, Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Winse Morishige
- Protein Engineering, Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Natalie Bezman
- Discovery Biology, Research and Early Development, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Pavel Strop
- Protein Engineering, Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Arvind Rajpal
- Protein Engineering, Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, California 94063, United States
| | - Olafur Gudmundsson
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey 08540, United States
| | - Guodong Chen
- Pharmaceutical Candidate Optimization, Nonclinical Research and Development, Bristol Myers Squibb Company, Princeton, New Jersey 08540, United States
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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: 130] [Impact Index Per Article: 32.5] [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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16
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Cheng M, Guo C, Gross ML. The Application of Fluorine-Containing Reagents in Structural Proteomics. Angew Chem Int Ed Engl 2020; 59:5880-5889. [PMID: 31588625 PMCID: PMC7485648 DOI: 10.1002/anie.201907662] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Indexed: 01/01/2023]
Abstract
Structural proteomics refers to large-scale mapping of protein structures in order to understand the relationship between protein sequence, structure, and function. Chemical labeling, in combination with mass-spectrometry (MS) analysis, have emerged as powerful tools to enable a broad range of biological applications in structural proteomics. The key to success is a biocompatible reagent that modifies a protein without affecting its high-order structure. Fluorine, well-known to exert profound effects on the physical and chemical properties of reagents, should have an impact on structural proteomics. In this Minireview, we describe several fluorine-containing reagents that can be applied in structural proteomics. We organize their applications around four MS-based techniques: a) affinity labeling, b) activity-based protein profiling (ABPP), c) protein footprinting, and d) protein cross-linking. Our aim is to provide an overview of the research, development, and application of fluorine-containing reagents in protein structural studies.
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Affiliation(s)
- Ming Cheng
- Department of Chemistry, Washington University in St Louis, St Louis, MO 63130
| | - Chunyang Guo
- Department of Chemistry, Washington University in St Louis, St Louis, MO 63130
| | - Michael L Gross
- Department of Chemistry, Washington University in St Louis, St Louis, MO 63130
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17
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Polasky DA, Dixit SM, Keating MF, Gadkari VV, Andrews PC, Ruotolo BT. Pervasive Charge Solvation Permeates Native-like Protein Ions and Dramatically Influences Top-down Sequencing Data. J Am Chem Soc 2020; 142:6750-6760. [DOI: 10.1021/jacs.0c01076] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Daniel A. Polasky
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Sugyan M. Dixit
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Michael F. Keating
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Varun V. Gadkari
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Philip C. Andrews
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
- Department of Biological Chemistry, University of Michigan, 1150 West Medical Center Drive, Ann Arbor Michigan 48109, United States
| | - Brandon T. Ruotolo
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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19
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Johnson DT, Punshon-Smith B, Espino JA, Gershenson A, Jones LM. Implementing In-Cell Fast Photochemical Oxidation of Proteins in a Platform Incubator with a Movable XY Stage. Anal Chem 2020; 92:1691-1696. [PMID: 31860269 PMCID: PMC7944481 DOI: 10.1021/acs.analchem.9b04933] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
Fast
photochemical oxidation of proteins (FPOP) is a protein footprinting
technique that is being increasingly used in MS-based proteomics.
FPOP is utilized to study protein–protein interactions, protein–ligand
interactions, and protein conformational dynamics. This method has
recently been extended to protein labeling in live cells (IC-FPOP),
allowing the study of protein conformations in the complex cellular
environment. Traditionally, IC-FPOP has been executed using a single
cell flow system, in which hydrodynamic focusing drives cells along
in a single file line, keeping the cells from clumping and thus ensuring
equal exposure to the laser irradiation required for photochemical
oxidation. Here, we introduce a novel platform that allows IC-FPOP
to occur in a sterile incubation system complete with a mobile stage
for XY movement, peristaltic pumps equipped with perfusion lines for
chemical transport, and mirrors for laser beam guidance. This new
system, called Platform Incubator with movable XY stage (PIXY), also
utilizes software enabling automated communication between equipment
and execution of the entire system. Further, comparison with a standard
IC-FPOP flow system results reveal that this platform can successfully
be used in lieu of the flow system while also decreasing the time
to complete analysis of a single sample.
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Affiliation(s)
- Danté T Johnson
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Benjamin Punshon-Smith
- Technology Research Center , University of Maryland Baltimore County , Catonsville , Maryland 21250 , United States
| | - Jessica A Espino
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Anne Gershenson
- Department of Biochemistry and Molecular Biology , University of Massachusetts , Amherst , Massachusetts 01003 , United States
| | - Lisa M Jones
- Department of Pharmaceutical Sciences , University of Maryland , Baltimore , Maryland 21201 , United States
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20
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Liu XR, Rempel DL, Gross ML. Composite Conformational Changes of Signaling Proteins upon Ligand Binding Revealed by a Single Approach: Calcium-Calmodulin Study. Anal Chem 2019; 91:12560-12567. [PMID: 31487155 DOI: 10.1021/acs.analchem.9b03491] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Signaling proteins exemplified by calmodulin usually bind cooperatively to multiple ligands. Intermediate states and allosteric behavior are difficult to characterize. Here we extend a recently reported mass spectrometry (MS)-based method named LITPOMS (ligand titration, fast photochemical oxidation of proteins and mass spectrometry) that characterizes complex binding systems typically found as signaling proteins. As reported previously, calmodulin's response to binding four Ca2+ can be determined by LITPOMS to reveal binding sites, binding order, and most importantly composite binding behavior. Modeling this behavior provides site-specific binding affinities. In this article, we dissect the composite, peptide-level conformational changes at several regions either by digestion with a different protease or by tandem MS of LITPOMS behavior at the amino-acid residue level. Such dissection greatly elevates spatial resolution and increases the confidence of binding-order assignment. These complementary views of complex protein conformational change recapitulate the cumulative understanding via a single approach, providing new insights on poorly understood yet important allostery and underpin an approach applicable for exploring other signaling systems.
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Affiliation(s)
- Xiaoran Roger Liu
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
| | - Don L Rempel
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
| | - Michael L Gross
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive , St. Louis , Missouri 63130 , United States
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21
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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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22
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Protein profiling and pseudo-parallel reaction monitoring to monitor a fusion-associated conformational change in hemagglutinin. Anal Bioanal Chem 2019; 411:4987-4998. [PMID: 31254054 DOI: 10.1007/s00216-019-01921-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/08/2019] [Accepted: 05/14/2019] [Indexed: 12/22/2022]
Abstract
Influenza infection requires viral escape from early endosomes into the cytosol, which is enabled by an acid-induced irreversible conformational transformation in the viral protein hemagglutinin. Despite the direct relationship between this conformational change and infectivity, label-free methods for characterizing this and other protein conformational changes in biological mixtures are limited. While the chemical reactivity of the protein backbone and side-chain residues is a proxy for protein conformation, coupling this reactivity to quantitative mass spectrometry is a challenge in complex environments. Herein, we evaluate whether electrophilic amidination coupled with pseudo-parallel reaction monitoring is an effective label-free approach to detect the fusion-associated conformational transformation in recombinant hemagglutinin (rHA). We identified rHA peptides that are differentially amidinated between the pre- and post-fusion states, and validated that this difference relies upon the fusion-associated conformational switch. We further demonstrate that we can distinguish the fusion profile in a matrix of digested cellular lysate. This fusion assay can be used to evaluate fusion competence for modified HA. Graphical abstract.
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23
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Schut GJ, Mohamed-Raseek N, Tokmina-Lukaszewska M, Mulder DW, Nguyen DMN, Lipscomb GL, Hoben JP, Patterson A, Lubner CE, King PW, Peters JW, Bothner B, Miller AF, Adams MWW. The catalytic mechanism of electron-bifurcating electron transfer flavoproteins (ETFs) involves an intermediary complex with NAD<sup/>. J Biol Chem 2019; 294:3271-3283. [PMID: 30567738 PMCID: PMC6398123 DOI: 10.1074/jbc.ra118.005653] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/11/2018] [Indexed: 12/20/2022] Open
Abstract
Electron bifurcation plays a key role in anaerobic energy metabolism, but it is a relatively new discovery, and only limited mechanistic information is available on the diverse enzymes that employ it. Herein, we focused on the bifurcating electron transfer flavoprotein (ETF) from the hyperthermophilic archaeon Pyrobaculum aerophilum The EtfABCX enzyme complex couples NADH oxidation to the endergonic reduction of ferredoxin and exergonic reduction of menaquinone. We developed a model for the enzyme structure by using nondenaturing MS, cross-linking, and homology modeling in which EtfA, -B, and -C each contained FAD, whereas EtfX contained two [4Fe-4S] clusters. On the basis of analyses using transient absorption, EPR, and optical titrations with NADH or inorganic reductants with and without NAD+, we propose a catalytic cycle involving formation of an intermediary NAD+-bound complex. A charge transfer signal revealed an intriguing interplay of flavin semiquinones and a protein conformational change that gated electron transfer between the low- and high-potential pathways. We found that despite a common bifurcating flavin site, the proposed EtfABCX catalytic cycle is distinct from that of the genetically unrelated bifurcating NADH-dependent ferredoxin NADP+ oxidoreductase (NfnI). The two enzymes particularly differed in the role of NAD+, the resting and bifurcating-ready states of the enzymes, how electron flow is gated, and the two two-electron cycles constituting the overall four-electron reaction. We conclude that P. aerophilum EtfABCX provides a model catalytic mechanism that builds on and extends previous studies of related bifurcating ETFs and can be applied to the large bifurcating ETF family.
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Affiliation(s)
- Gerrit J Schut
- From the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229
| | | | | | - David W Mulder
- the Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, and
| | - Diep M N Nguyen
- From the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229
| | - Gina L Lipscomb
- From the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229
| | - John P Hoben
- the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
| | - Angela Patterson
- the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
| | - Carolyn E Lubner
- the Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, and
| | - Paul W King
- the Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, and
| | - John W Peters
- the Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164
| | - Brian Bothner
- the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
| | - Anne-Frances Miller
- the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
| | - Michael W W Adams
- From the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229,
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24
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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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25
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Guo C, Cheng M, Gross ML. Protein-Metal-Ion Interactions Studied by Mass Spectrometry-Based Footprinting with Isotope-Encoded Benzhydrazide. Anal Chem 2018; 91:1416-1423. [PMID: 30495934 DOI: 10.1021/acs.analchem.8b04088] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Metal ions, usually bound by various amino-acid side chains in proteins, play multiple roles in protein folding, conformational change, cellular communication, and catalysis. Ca(II) and Mg(II), abundant among biologically relevant cations, execute their cellular functions associated with the conformational change of bound proteins. They bind with proteins where carboxylic acid residues are dominant ligands. To develop mass spectrometry for mapping protein-binding sites, we implemented a new carboxyl group footprinter, benzhydrazide, and refined it with isotope encoding. The method uses carbodiimide chemistry to footprint carboxylic residues, whereby 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide activates a carboxyl group followed by nucleophilic attack by benzhydrazide forming a stable labeled product. We tested the effectiveness of isotope-encoded benzhydrazide by studying Ca2+ and Mg2+ binding of calmodulin, an EF-hand protein. The footprinting results indicate that the four active sites for metal-ion binding (EF hands I, II, III, and IV) and the linker region (peptide 78-86) undergo conformational changes upon Ca(II) and Mg(II) binding, respectively. The outcome is consistent with previously reported results and 3-D structures, thereby validating a new reagent that is more reactive and discriminating for specific amino-acid protein footprinting. This reagent should be important for locating metal-binding sites of other metalloproteins.
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Affiliation(s)
- Chunyang Guo
- Department of Chemistry , Washington University , St. Louis , Missouri 63130 , United States
| | - Ming Cheng
- 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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26
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Tokmina-Lukaszewska M, Patterson A, Berry L, Scott L, Balasubramanian N, Bothner B. The Role of Mass Spectrometry in Structural Studies of Flavin-Based Electron Bifurcating Enzymes. Front Microbiol 2018; 9:1397. [PMID: 30026733 PMCID: PMC6041385 DOI: 10.3389/fmicb.2018.01397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 06/07/2018] [Indexed: 12/01/2022] Open
Abstract
For decades, biologists and biochemists have taken advantage of atomic resolution structural models of proteins from X-ray crystallography, nuclear magnetic resonance spectroscopy, and more recently cryo-electron microscopy. However, not all proteins relent to structural analyses using these approaches, and as the depth of knowledge increases, additional data elucidating a mechanistic understanding of protein function is desired. Flavin-based electron bifurcating enzymes, which are responsible for producing high energy compounds through the simultaneous endergonic and exergonic reduction of two intercellular electron carriers (i.e., NAD+ and ferredoxin) are one class of proteins that have challenged structural biologists and in which there is great interest to understand the mechanism behind electron gating. A limited number of X-ray crystallography projects have been successful; however, it is clear that to understand how these enzymes function, techniques that can reveal detailed in solution information about protein structure, dynamics, and interactions involved in the bifurcating reaction are needed. In this review, we cover a general set of mass spectrometry-based techniques that, combined with protein modeling, are capable of providing information on both protein structure and dynamics. Techniques discussed include surface labeling, covalent cross-linking, native mass spectrometry, and hydrogen/deuterium exchange. We cover how biophysical data can be used to validate computationally generated protein models and develop mechanistic explanations for regulation and performance of enzymes and protein complexes. Our focus will be on flavin-based electron bifurcating enzymes, but the broad applicability of the techniques will be showcased.
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Affiliation(s)
| | - Angela Patterson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Luke Berry
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | - Liam Scott
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
| | | | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, United States
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Paul TJ, Parac-Vogt TN, Quiñonero D, Prabhakar R. Investigating Polyoxometalate–Protein Interactions at Chemically Distinct Binding Sites. J Phys Chem B 2018; 122:7219-7232. [DOI: 10.1021/acs.jpcb.8b02931] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Thomas J. Paul
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | | | - David Quiñonero
- Department of Chemistry, Universitat de les Illes Balears, Palma de Mallorca 07122, Spain
| | - Rajeev Prabhakar
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
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28
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MS-based conformation analysis of recombinant proteins in design, optimization and development of biopharmaceuticals. Methods 2018; 144:134-151. [PMID: 29678586 DOI: 10.1016/j.ymeth.2018.04.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/10/2018] [Accepted: 04/12/2018] [Indexed: 01/18/2023] Open
Abstract
Mass spectrometry (MS)-based methods for analyzing protein higher order structures have gained increasing application in the field of biopharmaceutical development. The predominant methods used in this area include native MS, hydrogen deuterium exchange-MS, covalent labeling, cross-linking and limited proteolysis. These MS-based methods will be briefly described in this article, followed by a discussion on how these methods contribute at different stages of discovery and development of protein therapeutics.
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29
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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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30
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Lu Y, Liu H, Saer R, Li VL, Zhang H, Shi L, Goodson C, Gross ML, Blankenship RE. A Molecular Mechanism for Nonphotochemical Quenching in Cyanobacteria. Biochemistry 2017; 56:2812-2823. [PMID: 28513152 DOI: 10.1021/acs.biochem.7b00202] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cyanobacterial orange carotenoid protein (OCP) protects photosynthetic cyanobacteria from photodamage by dissipating excess excitation energy collected by phycobilisomes (PBS) as heat. Dissociation of the PBS-OCP complex in vivo is facilitated by another protein known as the fluorescence recovery protein (FRP), which primarily exists as a dimeric complex. We used various mass spectrometry (MS)-based techniques to investigate the molecular mechanism of this FRP-mediated process. FRP in the dimeric state (dFRP) retains its high affinity for the C-terminal domain (CTD) of OCP in the red state (OCPr). Site-directed mutagenesis and native MS suggest the head region on FRP is a candidate to bind OCP. After attachment to the CTD, the conformational changes of dFRP allow it to bridge the two domains, facilitating the reversion of OCPr into the orange state (OCPo) accompanied by a structural rearrangement of dFRP. Interestingly, we found a mutual response between FRP and OCP; that is, FRP and OCPr destabilize each other, whereas FRP and OCPo stabilize each other. A detailed mechanism of FRP function is proposed on the basis of the experimental results.
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Affiliation(s)
- Yue Lu
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Haijun Liu
- Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Department of Biology, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Rafael Saer
- Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Department of Biology, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Veronica L Li
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Hao Zhang
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Liuqing Shi
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Carrie Goodson
- Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Department of Biology, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Robert E Blankenship
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Photosynthetic Antenna Research Center, Washington University in St. Louis , St. Louis, Missouri 63130, United States.,Department of Biology, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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31
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Zhang Y, Wecksler AT, Molina P, Deperalta G, Gross ML. Mapping the Binding Interface of VEGF and a Monoclonal Antibody Fab-1 Fragment with Fast Photochemical Oxidation of Proteins (FPOP) and Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:850-858. [PMID: 28255747 PMCID: PMC5624547 DOI: 10.1007/s13361-017-1601-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 05/11/2023]
Abstract
We previously analyzed the Fab-1:VEGF (vascular endothelial growth factor) system described in this work, with both native top-down mass spectrometry and bottom-up mass spectrometry (carboxyl-group or GEE footprinting) techniques. This work continues bottom-up mass spectrometry analysis using a fast photochemical oxidation of proteins (FPOP) platform to map the solution binding interface of VEGF and a fragment antigen binding region of an antibody (Fab-1). In this study, we use FPOP to compare the changes in solvent accessibility by quantitating the extent of oxidative modification in the unbound versus bound states. Determining the changes in solvent accessibility enables the inference of the protein binding sites (epitope and paratopes) and a comparison to the previously published Fab-1:VEGF crystal structure, adding to the top-down and bottom-up data. Using this method, we investigated peptide-level and residue-level changes in solvent accessibility between the unbound proteins and bound complex. Mapping these data onto the Fab-1:VEGF crystal structure enabled successful characterization of both the binding region and regions of remote conformation changes. These data, coupled with our previous higher order structure (HOS) studies, demonstrate the value of a comprehensive toolbox of methods for identifying the putative epitopes and paratopes for biotherapeutic antibodies. Graphical abstract ᅟ.
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Affiliation(s)
- Ying Zhang
- Center for Biomedical and Bioorganic Mass Spectrometry, Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Analytical Research and Development, Pfizer Inc., Andover, MA, 01810, USA
| | - Aaron T Wecksler
- Protein Analytical Chemistry, Genentech Inc., South San Francisco, CA, 94080, USA.
| | - Patricia Molina
- Protein Analytical Chemistry, Genentech Inc., South San Francisco, CA, 94080, USA
| | - Galahad Deperalta
- Protein Analytical Chemistry, Genentech Inc., South San Francisco, CA, 94080, USA
| | - Michael L Gross
- Center for Biomedical and Bioorganic Mass Spectrometry, Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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Pan LY, Salas-Solano O, Valliere-Douglass JF. Localized conformational interrogation of antibody and antibody-drug conjugates by site-specific carboxyl group footprinting. MAbs 2016; 9:307-318. [PMID: 27929747 DOI: 10.1080/19420862.2016.1268306] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Establishing and maintaining conformational integrity of monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) during development and manufacturing is critical for ensuring their clinical efficacy. As presented here, we applied site-specific carboxyl group footprinting (CGF) for localized conformational interrogation of mAbs. The approach relies on covalent labeling that introduces glycine ethyl ester tags onto solvent-accessible side chains of protein carboxylates. Peptide mapping is used to monitor the labeling kinetics of carboxyl residues and the labeling kinetics reflects the conformation or solvent-accessibility of side chains. Our results for two case studies are shown here. The first study was aimed at defining the conformational changes of mAbs induced by deglycosylation. We found that two residues in CH2 domain (D268 and E297) show significantly enhanced side chain accessibility upon deglycosylation. This site-specific result highlighted the advantage of monitoring the labeling kinetics at the amino acid level as opposed to the peptide level, which would result in averaging out of highly localized conformational differences. The second study was designed to assess conformational effects brought on by conjugation of mAbs with drug-linkers. All 59 monitored carboxyl residues displayed similar solvent-accessibility between the ADC and mAb under native conditions, which suggests the ADC and mAb share similar side chain conformation. The findings are well correlated and complementary with results from other assays. This work illustrated that site-specific CGF is capable of pinpointing local conformational changes in mAbs or ADCs that might arise during development and manufacturing. The methodology can be readily implemented within the industry to provide comprehensive conformational assessment of these molecules.
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Leitner A. Cross-linking and other structural proteomics techniques: how chemistry is enabling mass spectrometry applications in structural biology. Chem Sci 2016; 7:4792-4803. [PMID: 30155128 PMCID: PMC6016523 DOI: 10.1039/c5sc04196a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 04/25/2016] [Indexed: 01/05/2023] Open
Abstract
The biological function of proteins is heavily influenced by their structures and their organization into assemblies such as protein complexes and regulatory networks. Mass spectrometry (MS) has been a key enabling technology for high-throughput and comprehensive protein identification and quantification on a proteome-wide scale. Besides these essential contributions, MS can also be used to study higher-order structures of biomacromolecules in a variety of ways. In one approach, intact proteins or protein complexes may be directly probed in the mass spectrometer. Alternatively, various forms of solution-phase chemistry are used to introduce modifications in intact proteins and localizing these modifications by MS analysis at the peptide level is used to derive structural information. Here, I will put a spotlight on the central role of chemistry in such mass spectrometry-based methods that bridge proteomics and structural biology, with a particular emphasis on chemical cross-linking of protein complexes.
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Affiliation(s)
- Alexander Leitner
- Department of Biology , Institute of Molecular Systems Biology , ETH Zurich , Auguste-Piccard-Hof 1 , 8093 Zurich , Switzerland .
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34
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Kaur P, Tomechko SE, Kiselar J, Shi W, Deperalta G, Wecksler AT, Gokulrangan G, Ling V, Chance MR. Characterizing monoclonal antibody structure by carboxyl group footprinting. MAbs 2016; 7:540-52. [PMID: 25933350 DOI: 10.1080/19420862.2015.1023683] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Structural characterization of proteins and their antigen complexes is essential to the development of new biologic-based medicines. Amino acid-specific covalent labeling (CL) is well suited to probe such structures, especially for cases that are difficult to examine by alternative means due to size, complexity, or instability. We present here a detailed account of carboxyl group labeling (with glycine ethyl ester (GEE) tagging) applied to a glycosylated monoclonal antibody therapeutic (mAb). The experiments were optimized to preserve the structural integrity of the mAb, and experimental conditions were varied and replicated to establish the reproducibility of the technique. Homology-based models were generated and used to compare the solvent accessibility of the labeled residues, which include aspartic acid (D), glutamic acid (E), and the C-terminus (i.e., the target probes), with the experimental data in order to understand the accuracy of the approach. Data from the mAb were compared to reactivity measures of several model peptides to explain observed variations in reactivity. Attenuation of reactivity in otherwise solvent accessible probes is documented as arising from the effects of positive charge or bond formation between adjacent amine and carboxyl groups, the latter accompanied by observed water loss. A comparison of results with previously published data by Deperalta et al using hydroxyl radical footprinting showed that 55% (32/58) of target residues were GEE labeled in this study whereas the previous study reported 21% of the targets were labeled. Although the number of target residues in GEE labeling is fewer, the two approaches provide complementary information. The results highlight advantages of this approach, such as the ease of use at the bench top, the linearity of the dose response plots at high levels of labeling, reproducibility of replicate experiments (<2% variation in modification extent), the similar reactivity of the three target probes, and significant correlation of reactivity and solvent accessible surface area.
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Key Words
- 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide
- ACN, acetonitrile
- CD, circular dichroism
- CL, covalent labeling
- DR, dose response
- EDC, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide
- EIC, extracted ion chromatogram
- GEE, glycine ethyl ester
- HC, heavy chain
- HDX, hydrogen-deuterium exchange
- HRF, hydroxyl radical footprinting
- IT, ion trap
- IgG, immunoglobulin gamma
- LC, light chain
- Lys-C, lysyl endopeptidase
- MS, mass spectrometry
- RC, rate constant
- SASA, solvent accessible surface area
- SEC, size-exclusion chromatography
- acetonitrile
- circular dichroism
- covalent labeling
- dose response
- extracted ion chromatogram
- glycine ethyl ester
- heavy chain
- hydrogen-deuterium exchange
- hydroxyl radical footprinting
- immunoglobulin gamma
- ion trap
- light chain
- lysyl endopeptidase
- mAb, monoclonal antibody
- mass spectrometry
- monoclonal antibody
- rate constant
- size-exclusion chromatography
- solvent accessible surface area
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Affiliation(s)
- Parminder Kaur
- a Center for Proteomics and Bioinformatics; School of Medicine; Case Western Reserve University ; Cleveland , OH , USA
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35
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Zhang B, Rempel DL, Gross ML. Protein Footprinting by Carbenes on a Fast Photochemical Oxidation of Proteins (FPOP) Platform. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:552-5. [PMID: 26679355 PMCID: PMC4758905 DOI: 10.1007/s13361-015-1313-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/11/2015] [Accepted: 11/24/2015] [Indexed: 05/02/2023]
Abstract
Protein footprinting combined with mass spectrometry provides a method to study protein structures and interactions. To improve further current protein footprinting methods, we adapted the fast photochemical oxidation of proteins (FPOP) platform to utilize carbenes as the footprinting reagent. A Nd-YAG laser provides 355 nm laser for carbene generation in situ from photoleucine as the carbene precursor in a flow system with calmodulin as the test protein. Reversed-phase liquid chromatography coupled with mass spectrometry is appropriate to analyze the modifications produced in this footprinting. By comparing the modification extent of apo and holo calmodulin on the peptide level, we can resolve different structural domains of the protein. Carbene footprinting in a flow system is promising.
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Affiliation(s)
- Bojie Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Don L Rempel
- 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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36
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Yefremova Y, Al-Majdoub M, Opuni KF, Koy C, Yan Y, Gross M, Glocker MO. A Dynamic Model of pH-Induced Protein G'e Higher Order Structure Changes derived from Mass Spectrometric Analyses. Anal Chem 2016; 88:890-7. [PMID: 26606592 PMCID: PMC5201196 DOI: 10.1021/acs.analchem.5b03536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To obtain insight into pH change-driven molecular dynamics, we studied the higher order structure changes of protein G'e at the molecular and amino acid residue levels in solution by using nanoESI- and IM-mass spectrometry, CD spectroscopy, and protein chemical modification reactions (protein footprinting). We found a dramatic change of the overall tertiary structure of protein G'e when the pH was changed from neutral to acidic, whereas its secondary structure features remained nearly invariable. Limited proteolysis and surface-topology mapping of protein G'e by fast photochemical oxidation of proteins (FPOP) under neutral and acidic conditions reveal areas where higher order conformational changes occur on the amino-acid residue level. Under neutral solution conditions, lower oxidation occurs for residues of the first linker region, whereas greater oxidative modifications occur for amino-acid residues of the IgG-binding domains I and II. We propose a dynamic model of pH-induced structural changes in which protein G'e at neutral pH adopts an overall tight conformation with all four domains packed in a firm assembly, whereas at acidic pH, the three IgG-binding domains form an elongated alignment, and the N-terminal, His-tag-carrying domain unfolds. At the same time the individual IgG-binding domains themselves seem to adopt a more compacted fold. As the secondary structure features are nearly unchanged at either pH, interchange between both conformations is highly reversible, explaining the high reconditioning power of protein G'e-based affinity chromatography columns.
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Affiliation(s)
- Yelena Yefremova
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | | | | | - Cornelia Koy
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | - Yuetian Yan
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 USA
| | - Michael Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri 63130 USA
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Zhang H, Liu H, Blankenship RE, Gross ML. Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:178-81. [PMID: 26384685 PMCID: PMC4688080 DOI: 10.1007/s13361-015-1260-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/27/2015] [Accepted: 08/28/2015] [Indexed: 05/03/2023]
Abstract
We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting.
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Affiliation(s)
- Hao Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Haijun Liu
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO, 63130, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Robert E Blankenship
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO, 63130, USA
- Department of Biology, 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.
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, St. Louis, MO, 63130, USA.
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38
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Wecksler AT, Kalo MS, Deperalta G. Mapping of Fab-1:VEGF Interface Using Carboxyl Group Footprinting Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:2077-2080. [PMID: 26419770 DOI: 10.1007/s13361-015-1273-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 09/04/2015] [Accepted: 09/05/2015] [Indexed: 06/05/2023]
Abstract
A proof-of-concept study was performed to demonstrate that carboxyl group footprinting, a relatively simple, bench-top method, has utility for first-pass analysis to determine epitope regions of therapeutic mAb:antigen complexes. The binding interface of vascular endothelial growth factor (VEGF) and the Fab portion of a neutralizing antibody (Fab-1) was analyzed using carboxyl group footprinting with glycine ethyl ester (GEE) labeling. Tryptic peptides involved in the binding interface between VEGF and Fab-1 were identified by determining the specific GEE-labeled residues that exhibited a reduction in the rate of labeling after complex formation. A significant reduction in the rate of GEE labeling was observed for E93 in the VEGF tryptic peptide V5, and D28 and E57 in the Fab-1 tryptic peptides HC2 and HC4, respectively. Results from the carboxyl group footprinting were compared with the binding interface identified from a previously characterized crystal structure (PDB: 1BJ1). All of these residues are located at the Fab-1:VEGF interface according to the crystal structure, demonstrating the potential utility of carboxyl group footprinting with GEE labeling for mapping epitopes. Graphical Abstract ᅟ.
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Affiliation(s)
- Aaron T Wecksler
- Protein Analytical Chemistry Department, Genentech Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Matt S Kalo
- Protein Analytical Chemistry Department, Genentech Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Galahad Deperalta
- Protein Analytical Chemistry Department, Genentech Inc., 1 DNA Way, South San Francisco, CA, 94080, USA.
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Heinz S, Liauw P, Nickelsen J, Nowaczyk M. Analysis of photosystem II biogenesis in cyanobacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:274-87. [PMID: 26592144 DOI: 10.1016/j.bbabio.2015.11.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 11/13/2015] [Accepted: 11/15/2015] [Indexed: 11/25/2022]
Abstract
Photosystem II (PSII), a large multisubunit membrane protein complex found in the thylakoid membranes of cyanobacteria, algae and plants, catalyzes light-driven oxygen evolution from water and reduction of plastoquinone. Biogenesis of PSII requires coordinated assembly of at least 20 protein subunits, as well as incorporation of various organic and inorganic cofactors. The stepwise assembly process is facilitated by numerous protein factors that have been identified in recent years. Further analysis of this process requires the development or refinement of specific methods for the identification of novel assembly factors and, in particular, elucidation of the unique role of each. Here we summarize current knowledge of PSII biogenesis in cyanobacteria, focusing primarily on the impact of methodological advances and innovations. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux.
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Affiliation(s)
- Steffen Heinz
- Molekulare Pflanzenwissenschaften, Biozentrum LMU München, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany
| | - Pasqual Liauw
- Biochemie der Pflanzen, Ruhr Universität Bochum, Universitätsstr. 150, 44801 Bochum, Germany
| | - Jörg Nickelsen
- Molekulare Pflanzenwissenschaften, Biozentrum LMU München, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany.
| | - Marc Nowaczyk
- Biochemie der Pflanzen, Ruhr Universität Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
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Kaur P, Tomechko S, Kiselar J, Shi W, Deperalta G, Wecksler AT, Gokulrangan G, Ling V, Chance MR. Characterizing monoclonal antibody structure by carbodiimide/GEE footprinting. MAbs 2015; 6:1486-99. [PMID: 25484052 DOI: 10.4161/19420862.2014.975096] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Amino acid-specific covalent labeling is well suited to probe protein structure and macromolecular interactions, especially for macromolecules and their complexes that are difficult to examine by alternative means, due to size, complexity, or instability. Here we present a detailed account of carbodiimide-based covalent labeling (with GEE tagging) applied to a glycosylated monoclonal antibody therapeutic, which represents an important class of biologic drugs. Characterization of such proteins and their antigen complexes is essential to development of new biologic-based medicines. In this study, the experiments were optimized to preserve the structural integrity of the protein, and experimental conditions were varied and replicated to establish the reproducibility and precision of the technique. Homology-based models were generated and used to compare the solvent accessibility of the labeled residues, which include D, E, and the C-terminus, against the experimental surface accessibility data in order to understand the accuracy of the approach in providing an unbiased assessment of structure. Data from the protein were also compared to reactivity measures of several model peptides to explain sequence or structure-based variations in reactivity. The results highlight several advantages of this approach. These include: the ease of use at the bench top, the linearity of the dose response plots at high levels of labeling (indicating that the label does not significantly perturb the structure of the protein), the high reproducibility of replicate experiments (<2 % variation in modification extent), the similar reactivity of the 3 target probe residues (as suggested by analysis of model peptides), and the overall positive and significant correlation of reactivity and solvent accessible surface area (the latter values predicted by the homology modeling). Attenuation of reactivity, in otherwise solvent accessible probes, is documented as arising from the effects of positive charge or bond formation between adjacent amine and carboxyl groups, the latter accompanied by observed water loss. The results are also compared with data from hydroxyl radical-mediated oxidative footprinting on the same protein, showing that complementary information is gained from the 2 approaches, although the number of target residues in carbodiimide/GEE labeling is fewer. Overall, this approach is an accurate and precise method for assessing protein structure of biologic drugs.
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Key Words
- ACN, acetonitrile
- CD, circular dichroism
- CL, covalent labeling
- DR, dose response
- EDC, 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide
- EIC, extracts the ion chromatogram
- FPOP, fast photochemical oxidation of proteins
- GEE
- GEE, glycine ethyl ester
- HC, heavy chain
- HDX, hydrogen-deuterium exchange
- HRF, hydroxyl radical footprinting
- IT, ion trap
- IgG, immunoglobulin gamma
- LC, light chain
- LysC, Lysyl endopeptidase
- MS, mass spectrometry
- NMR, nuclear magnetic resonance
- RC, rate constant
- SASA, solvent accessible surface area
- SEC, size-exclusion chromatography
- VEGF, vascular endothelial growth factor
- covalent labeling
- footprinting
- mAb, monoclonal antibody
- protein structure
- structural proteomics
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Affiliation(s)
- Parminder Kaur
- a Center for Proteomics and Bioinformatics ; Case Western Reserve University ; Cleveland , OH USA
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Liu H, Zhang H, King JD, Wolf NR, Prado M, Gross ML, Blankenship RE. Mass spectrometry footprinting reveals the structural rearrangements of cyanobacterial orange carotenoid protein upon light activation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1837:1955-1963. [PMID: 25256653 DOI: 10.1016/j.bbabio.2014.09.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/09/2014] [Accepted: 09/12/2014] [Indexed: 11/25/2022]
Abstract
The orange carotenoid protein (OCP), a member of the family of blue light photoactive proteins, is required for efficient photoprotection in many cyanobacteria. Photoexcitation of the carotenoid in the OCP results in structural changes within the chromophore and the protein to give an active red form of OCP that is required for phycobilisome binding and consequent fluorescence quenching. We characterized the light-dependent structural changes by mass spectrometry-based carboxyl footprinting and found that an α helix in the N-terminal extension of OCP plays a key role in this photoactivation process. Although this helix is located on and associates with the outside of the β-sheet core in the C-terminal domain of OCP in the dark, photoinduced changes in the domain structure disrupt this interaction. We propose that this mechanism couples light-dependent carotenoid conformational changes to global protein conformational dynamics in favor of functional phycobilisome binding, and is an essential part of the OCP photocycle.
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Affiliation(s)
- Haijun Liu
- Department of Biology, Washington University in St. Louis, MO 63130, USA; Department of Chemistry, Washington University in St. Louis, MO 63130, USA; Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA.
| | - Hao Zhang
- Department of Chemistry, Washington University in St. Louis, MO 63130, USA; Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA
| | - Jeremy D King
- Department of Biology, Washington University in St. Louis, MO 63130, USA; Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA
| | - Nathan R Wolf
- Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA
| | - Mindy Prado
- Department of Biology, Washington University in St. Louis, MO 63130, USA; Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, MO 63130, USA; Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA
| | - Robert E Blankenship
- Department of Biology, Washington University in St. Louis, MO 63130, USA; Department of Chemistry, Washington University in St. Louis, MO 63130, USA; Photosynthetic Antenna Research Center (PARC), Washington University in St. Louis, MO 63130, USA
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Affiliation(s)
- Gregory
F. Pirrone
- Department of Chemistry and
Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, Massachusetts 02115 United States
| | - Roxana E. Iacob
- Department of Chemistry and
Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, Massachusetts 02115 United States
| | - John R. Engen
- Department of Chemistry and
Chemical Biology, Northeastern University, 360 Huntington Ave., Boston, Massachusetts 02115 United States
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Zhang H, Cui W, Gross ML. Mass spectrometry for the biophysical characterization of therapeutic monoclonal antibodies. FEBS Lett 2013; 588:308-17. [PMID: 24291257 DOI: 10.1016/j.febslet.2013.11.027] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 11/16/2013] [Accepted: 11/18/2013] [Indexed: 10/26/2022]
Abstract
Monoclonal antibodies (mAbs) are powerful therapeutics, and their characterization has drawn considerable attention and urgency. Unlike small-molecule drugs (150-600 Da) that have rigid structures, mAbs (∼150 kDa) are engineered proteins that undergo complicated folding and can exist in a number of low-energy structures, posing a challenge for traditional methods in structural biology. Mass spectrometry (MS)-based biophysical characterization approaches can provide structural information, bringing high sensitivity, fast turnaround, and small sample consumption. This review outlines various MS-based strategies for protein biophysical characterization and then reviews how these strategies provide structural information of mAbs at the protein level (intact or top-down approaches), peptide, and residue level (bottom-up approaches), affording information on higher order structure, aggregation, and the nature of antibody complexes.
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Affiliation(s)
- Hao Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Weidong Cui
- 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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Liu H, Chen J, Huang RYC, Weisz D, Gross ML, Pakrasi HB. Mass spectrometry-based footprinting reveals structural dynamics of loop E of the chlorophyll-binding protein CP43 during photosystem II assembly in the cyanobacterium Synechocystis 6803. J Biol Chem 2013; 288:14212-14220. [PMID: 23546881 DOI: 10.1074/jbc.m113.467613] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PSII repair cycle is required for sustainable photosynthesis in oxygenic photosynthetic organisms. In cyanobacteria and higher plants, proteolysis of the precursor D1 protein (pD1) to expose a C-terminal carboxylate group is an essential step leading to coordination of the Mn4CaO5 cluster, the site of water oxidation. Psb27 appears to associate with both pD1- and D1-containing PSII assembly intermediates by closely interacting with CP43. Here, we report that reduced binding affinity between CP43 and Psb27 is triggered by the removal of the C-terminal extension of the pD1 protein. A mass spectrometry-based footprinting strategy was adopted to probe solvent-exposed aspartic and glutamic acid residues on the CP43 protein. By comparing the extent of footprinting between HT3ΔctpAΔ27PSII and HT3ΔctpAPSII, two genetically modified PSII assembly complexes, we found that Psb27 binds to CP43 on the side of Loop E distal to the pseudo-symmetrical D1-D2 axis. By comparing a second pair of PSII assembly complexes, we discovered that Loop E of CP43 undergoes a significant conformational rearrangement due to the removal of the pD1 C-terminal extension, altering the Psb27-CP43 binding interface. The significance of this conformational rearrangement is discussed in the context of recruitment of the PSII lumenal extrinsic proteins and Mn4CaO5 cluster assembly. In addition to CP43's previously known function as one of the core PSII antenna proteins, this work demonstrates that Loop E of CP43 plays an important role in the functional assembly of the Water Oxidizing Center (WOC) during PSII biogenesis.
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Affiliation(s)
- Haijun Liu
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Jiawei Chen
- Department of Chemistry, Washington University, St. Louis, Missouri 63130
| | - Richard Y-C Huang
- Department of Chemistry, Washington University, St. Louis, Missouri 63130
| | - Daniel Weisz
- Department of Biology, Washington University, St. Louis, Missouri 63130; Department of Chemistry, Washington University, St. Louis, Missouri 63130
| | - Michael L Gross
- Department of Chemistry, Washington University, St. Louis, Missouri 63130
| | - Himadri B Pakrasi
- Department of Biology, Washington University, St. Louis, Missouri 63130.
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