1
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Tokmina-Lukaszewska M, Huang Q, Berry L, Kallas H, Peters JW, Seefeldt LC, Raugei S, Bothner B. Fe protein docking transduces conformational changes to MoFe nitrogenase active site in a nucleotide-dependent manner. Commun Chem 2023; 6:254. [PMID: 37980448 PMCID: PMC10657360 DOI: 10.1038/s42004-023-01046-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 10/30/2023] [Indexed: 11/20/2023] Open
Abstract
The reduction of dinitrogen to ammonia catalyzed by nitrogenase involves a complex series of events, including ATP hydrolysis, electron transfer, and activation of metal clusters for N2 reduction. Early evidence shows that an essential part of the mechanism involves transducing information between the nitrogenase component proteins through conformational dynamics. Here, millisecond time-resolved hydrogen-deuterium exchange mass spectrometry was used to unravel peptide-level protein motion on the time scale of catalysis of Mo-dependent nitrogenase from Azotobacter vinelandii. Normal mode analysis calculations complemented this data, providing insights into the specific signal transduction pathways that relay information across protein interfaces at distances spanning 100 Å. Together, these results show that conformational changes induced by protein docking are rapidly transduced to the active site, suggesting a specific mechanism for activating the metal cofactor in the enzyme active site.
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Affiliation(s)
| | - Qi Huang
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Luke Berry
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA
| | - Hayden Kallas
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - John W Peters
- Institute of Biological Chemistry, The University of Oklahoma, Norman, OK, USA
| | - Lance C Seefeldt
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT, USA
| | - Simone Raugei
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Brian Bothner
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA.
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2
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McGee JP, Melani RD, Des Soye B, Croote D, Winton V, Quake SR, Kafader JO, Kelleher NL. Immunocomplexed Antigen Capture and Identification by Native Top-Down Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:2093-2097. [PMID: 37683262 PMCID: PMC10557138 DOI: 10.1021/jasms.3c00235] [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] [Received: 06/29/2023] [Revised: 08/26/2023] [Accepted: 09/01/2023] [Indexed: 09/10/2023]
Abstract
Antibody-antigen interactions are central to the immune response. Variation of protein antigens such as isoforms and post-translational modifications can alter their antibody binding sites. To directly connect the recognition of protein antigens with their molecular composition, we probed antibody-antigen complexes by using native tandem mass spectrometry. Specifically, we characterized the prominent peanut allergen Ara h 2 and a convergent IgE variable region discovered in patients who are allergic to peanuts. In addition to measuring the antigen-induced dimerization of IgE antibodies, we demonstrated how immunocomplexes can be isolated in the gas phase and activated to eject, identify, and characterize proteoforms of their bound antigens. Using tandem experiments, we isolated the ejected antigens and then fragmented them to identify their chemical composition. These results establish native top-down mass spectrometry as a viable platform for precise and thorough characterization of immunocomplexes to relate structure to function and enable the discovery of antigen proteoforms and their binding sites.
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Affiliation(s)
- John P. McGee
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Rafael D. Melani
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Ben Des Soye
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Derek Croote
- Department
of Bioengineering, Stanford University, Stanford, California 94305, United States
| | - Valerie Winton
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Stephen R. Quake
- Department
of Bioengineering, Stanford University, Stanford, California 94305, United States
- Department
of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Jared O. Kafader
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
| | - Neil L. Kelleher
- Departments
of Chemistry and Molecular Biosciences and the Proteomics Center of
Excellence, Northwestern University, Evanston, Illinois 60208, United States
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3
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Du C, Cleary SP, Kostelic MM, Jones BJ, Kafader JO, Wysocki VH. Combining Surface-Induced Dissociation and Charge Detection Mass Spectrometry to Reveal the Native Topology of Heterogeneous Protein Complexes. Anal Chem 2023; 95:13889-13896. [PMID: 37672632 PMCID: PMC10874503 DOI: 10.1021/acs.analchem.3c02185] [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: 09/08/2023]
Abstract
Charge detection mass spectrometry (CDMS) enables the direct mass measurement of heterogeneous samples on the megadalton scale, as the charge state for a single ion is determined simultaneously with the mass-to-charge ratio (m/z). Surface-induced dissociation (SID) is an effective activation method to dissociate non-intertwined, non-covalent protein complexes without extensive gas-phase restructuring, producing various subcomplexes reflective of the native protein topology. Here, we demonstrate that using CDMS after SID on an Orbitrap platform offers subunit connectivity, topology, proteoform information, and relative interfacial strengths of the intact macromolecular assemblies. SID dissects the capsids (∼3.7 MDa) of adeno-associated viruses (AAVs) into trimer-containing fragments (3mer, 6mer, 9mer, 15mer, etc.) that can be detected by the individual ion mass spectrometry (I2MS) approach on Orbitrap instruments. SID coupled to CDMS provides unique structural insights into heterogeneous assemblies that are not readily obtained by traditional MS measurements.
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Affiliation(s)
- Chen Du
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Sean P Cleary
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Marius M Kostelic
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Benjamin J Jones
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jared O Kafader
- Departments of Chemistry, Molecular Biosciences, The Chemistry of Life Processes Institute, The Proteomics Center of Excellence at Northwestern University, Evanston, Illinois 60208, United States
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Resource for Native MS Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
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4
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Nash S, Vachet RW. Gas-Phase Unfolding of Protein Complexes Distinguishes Conformational Isomers. J Am Chem Soc 2022; 144:22128-22139. [PMID: 36414315 DOI: 10.1021/jacs.2c09573] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Proteins can adopt different conformational states that are important for their biological function and, in some cases, can be responsible for their dysfunction. The essential roles that proteins play in biological systems make distinguishing the structural differences between these conformational states both fundamentally and practically important. Here, we demonstrate that collision-induced unfolding (CIU), in combination with ion mobility-mass spectrometry (IM-MS) measurements, distinguish subtly different conformational states for protein complexes. Using the open and closed states of the β-lactoglobulin (βLG) dimer as a model, we show that these two conformational isomers unfold during collisional activation to generate distinct states that are readily separated by IM-MS. Extensive molecular modeling of the CIU process reproduces the distinct unfolding intermediates and identifies the molecular details that explain why the two conformational states unfold in distinct ways. Strikingly, the open conformational state forms new electrostatic interactions upon collisional heating, while the closed state does not. These newly formed electrostatic interactions involve residues on the loop differentially positioned in the two βLG conformational isomers, highlighting that gas-phase unfolding pathways reflect aspects of solution structure. This combination of experiment and theory provides a path forward for distinguishing subtly different conformational isomers for protein complexes via gas-phase unfolding experiments. Our results also have implications for understanding how protein complexes dissociate in the gas phase, indicating that current models need to be refined to explain protein complex dissociation.
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Affiliation(s)
- Stacey Nash
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Richard W Vachet
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States.,Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003 United States
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5
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Snyder DT, Harvey SR, Wysocki VH. Surface-induced Dissociation Mass Spectrometry as a Structural Biology Tool. Chem Rev 2022; 122:7442-7487. [PMID: 34726898 PMCID: PMC9282826 DOI: 10.1021/acs.chemrev.1c00309] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Native mass spectrometry (nMS) is evolving into a workhorse for structural biology. The plethora of online and offline preparation, separation, and purification methods as well as numerous ionization techniques combined with powerful new hybrid ion mobility and mass spectrometry systems has illustrated the great potential of nMS for structural biology. Fundamental to the progression of nMS has been the development of novel activation methods for dissociating proteins and protein complexes to deduce primary, secondary, tertiary, and quaternary structure through the combined use of multiple MS/MS technologies. This review highlights the key features and advantages of surface collisions (surface-induced dissociation, SID) for probing the connectivity of subunits within protein and nucleoprotein complexes and, in particular, for solving protein structure in conjunction with complementary techniques such as cryo-EM and computational modeling. Several case studies highlight the significant role SID, and more generally nMS, will play in structural elucidation of biological assemblies in the future as the technology becomes more widely adopted. Cases are presented where SID agrees with solved crystal or cryoEM structures or provides connectivity maps that are otherwise inaccessible by "gold standard" structural biology techniques.
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Affiliation(s)
- Dalton T. Snyder
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, OH 43210
| | - Sophie R. Harvey
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, OH 43210,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Vicki H. Wysocki
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, OH 43210,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210,Corresponding author:
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6
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Koy C, Opuni KFM, Danquah BD, Neamtu A, Glocker MO. Mass Spectrometric and Bio-Computational Binding Strength Analysis of Multiply Charged RNAse S Gas-Phase Complexes Obtained by Electrospray Ionization from Varying In-Solution Equilibrium Conditions. Int J Mol Sci 2021; 22:ijms221910183. [PMID: 34638522 PMCID: PMC8508491 DOI: 10.3390/ijms221910183] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/15/2021] [Accepted: 09/17/2021] [Indexed: 11/18/2022] Open
Abstract
We investigated the influence of a solvent’s composition on the stability of desorbed and multiply charged RNAse S ions by analyzing the non-covalent complex’s gas-phase dissociation processes. RNAse S was dissolved in electrospray ionization-compatible buffers with either increasing organic co-solvent content or different pHs. The direct transition of all the ions and the evaporation of the solvent from all the in-solution components of RNAse S under the respective in-solution conditions by electrospray ionization was followed by a collision-induced dissociation of the surviving non-covalent RNAse S complex ions. Both types of changes of solvent conditions yielded in mass spectrometrically observable differences of the in-solution complexation equilibria. Through quantitative analysis of the dissociation products, i.e., from normalized ion abundances of RNAse S, S-protein, and S-peptide, the apparent kinetic and apparent thermodynamic gas-phase complex properties were deduced. From the experimental data, it is concluded that the stability of RNAse S in the gas phase is independent of its in-solution equilibrium but is sensitive to the complexes’ gas-phase charge states. Bio-computational in-silico studies showed that after desolvation and ionization by electrospray, the remaining binding forces kept the S-peptide and S-protein together in the gas phase predominantly by polar interactions, which indirectly stabilized the in-bulk solution predominating non-polar intermolecular interactions. As polar interactions are sensitive to in-solution protonation, bio-computational results provide an explanation of quantitative experimental data with single amino acid residue resolution.
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Affiliation(s)
- Cornelia Koy
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18057 Rostock, Germany; (C.K.); (K.F.M.O.); (B.D.D.)
| | - Kwabena F. M. Opuni
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18057 Rostock, Germany; (C.K.); (K.F.M.O.); (B.D.D.)
- Department of Pharmaceutical Chemistry, School of Pharmacy, College of Health Science, University of Ghana, P.O. Box LG43, Legon, Ghana
| | - Bright D. Danquah
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18057 Rostock, Germany; (C.K.); (K.F.M.O.); (B.D.D.)
| | - Andrei Neamtu
- Department of Physiology, Grigore T. Popa University of Medicine and Pharmacy of Iasi, Str. Universitatii nr. 16, 700051 Iasi, Romania;
| | - Michael O. Glocker
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18057 Rostock, Germany; (C.K.); (K.F.M.O.); (B.D.D.)
- Correspondence: ; Tel.: +49-381-494-4930; Fax: +49-381-494-4932
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7
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Abstract
![]()
Native mass spectrometry
(MS) involves the analysis and characterization
of macromolecules, predominantly intact proteins and protein complexes,
whereby as much as possible the native structural features of the
analytes are retained. As such, native MS enables the study of secondary,
tertiary, and even quaternary structure of proteins and other biomolecules.
Native MS represents a relatively recent addition to the analytical
toolbox of mass spectrometry and has over the past decade experienced
immense growth, especially in enhancing sensitivity and resolving
power but also in ease of use. With the advent of dedicated mass analyzers,
sample preparation and separation approaches, targeted fragmentation
techniques, and software solutions, the number of practitioners and
novel applications has risen in both academia and industry. This review
focuses on recent developments, particularly in high-resolution native
MS, describing applications in the structural analysis of protein
assemblies, proteoform profiling of—among others—biopharmaceuticals
and plasma proteins, and quantitative and qualitative analysis of
protein–ligand interactions, with the latter covering lipid,
drug, and carbohydrate molecules, to name a few.
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Affiliation(s)
- Sem Tamara
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Maurits A den Boer
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
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8
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The challenge of structural heterogeneity in the native mass spectrometry studies of the SARS-CoV-2 spike protein interactions with its host cell-surface receptor. Anal Bioanal Chem 2021; 413:7205-7214. [PMID: 34389878 PMCID: PMC8362873 DOI: 10.1007/s00216-021-03601-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 07/28/2021] [Accepted: 08/04/2021] [Indexed: 11/13/2022]
Abstract
Native mass spectrometry (MS) enjoyed tremendous success in the past two decades in a wide range of studies aiming at understanding the molecular mechanisms of physiological processes underlying a variety of pathologies and accelerating the drug discovery process. However, the success record of native MS has been surprisingly modest with respect to the most recent challenge facing the biomedical community—the novel coronavirus infection (COVID-19). The major reason for the paucity of successful studies that use native MS to target various aspects of SARS-CoV-2 interaction with its host is the extreme degree of heterogeneity of the viral protein playing a key role in the host cell invasion. Indeed, the SARS-CoV-2 spike protein (S-protein) is extensively glycosylated, presenting a formidable challenge for native MS as a means of characterizing its interactions with both the host cell–surface receptor ACE2 and the drug candidates capable of disrupting this interaction. In this work, we evaluate the utility of native MS complemented with the experimental methods using gas-phase chemistry (limited charge reduction) to obtain meaningful information on the association of the S1 domain of the S-protein with the ACE2 ectodomain, and the influence of a small synthetic heparinoid on this interaction. Native MS reveals the presence of several different S1 oligomers in solution and allows the stoichiometry of the most prominent S1/ACE2 complexes to be determined. This enables meaningful interpretation of the changes in native MS that are observed upon addition of a small synthetic heparinoid (the pentasaccharide fondaparinux) to the S1/ACE2 solution, confirming that the small polyanion destabilizes the protein/receptor binding.
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9
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Yang Y, Ivanov DG, Kaltashov IA. The challenge of structural heterogeneity in the native mass spectrometry studies of the SARS-CoV-2 spike protein interactions with its host cell-surface receptor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021. [PMID: 34189525 DOI: 10.1101/2021.06.20.449191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Native mass spectrometry (MS) enjoyed tremendous success in the past two decades in a wide range of studies aiming at understanding the molecular mechanisms of physiological processes underlying a variety of pathologies and accelerating the drug discovery process. However, the success record of native MS has been surprisingly modest with respect to the most recent challenge facing the biomedical community â€" the novel coronavirus infection (COVID-19). The major reason for the paucity of successful studies that use native MS to target various aspects of SARS-CoV-2 interaction with its host is the extreme degree of structural heterogeneity of the viral protein playing a key role in the host cell invasion. Indeed, the SARS-CoV-2 spike protein (S-protein) is extensively glycosylated, presenting a formidable challenge for native mass spectrometry (MS) as a means of characterizing its interactions with both the host cell-surface receptor ACE2 and the drug candidates capable of disrupting this interaction. In this work we evaluate the utility of native MS complemented with the experimental methods using gas-phase chemistry (limited charge reduction) to obtain meaningful information on the association of the S1 domain of the S-protein with the ACE2 ectodomain, and the influence of a small synthetic heparinoid on this interaction. Native MS reveals the presence of several different S1 oligomers in solution and allows the stoichiometry of the most prominent S1/ACE2 complexes to be determined. This enables meaningful interpretation of the changes in native MS that are observed upon addition of a small synthetic heparinoid (the pentasaccharide fondaparinux) to the S1/ACE2 solution, confirming that the small polyanion destabilizes the protein/receptor binding.
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10
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Harvey SR, VanAernum ZL, Wysocki VH. Surface-Induced Dissociation of Anionic vs Cationic Native-Like Protein Complexes. J Am Chem Soc 2021; 143:7698-7706. [PMID: 33983719 DOI: 10.1021/jacs.1c00855] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Characterizing protein-protein interactions, stoichiometries, and subunit connectivity is key to understanding how subunits assemble into biologically relevant, multisubunit protein complexes. Native mass spectrometry (nMS) has emerged as a powerful tool to study protein complexes due to its low sample consumption and tolerance for heterogeneity. In nMS, positive mode ionization is routinely used and charge reduction, through the addition of solution additives, is often used, as the resulting lower charge states are often considered more native-like. When fragmented by surface-induced dissociation (SID), charge reduced complexes often give increased structural information over their "normal-charged" counterparts. A disadvantage of solution phase charge reduction is that increased adduction, and hence peak broadening, is often observed. Previous studies have shown that protein complexes ionized using negative mode generally form lower charge states relative to positive mode. Here we demonstrate that the lower charged protein complex anions activated by surface collisions fragment in a manner consistent with their solved structures, hence providing substructural information. Negative mode ionization in ammonium acetate offers the advantage of charge reduction without the peak broadening associated with solution phase charge reduction additives and provides direct structural information when coupled with SID. SID of 20S human proteasome (a 28-mer comprised of four stacked heptamer rings in an αββα formation), for example, provides information on both substructure (e.g., splitting into a 7α ring and the corresponding ββα 21-mer, and into α dimers and trimers to provide connectivity around the 7 α ring) and proteoform information on monomers.
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Affiliation(s)
- Sophie R Harvey
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Zachary L VanAernum
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, Ohio 43210, United States
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11
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Sever AIM, Yin V, Konermann L. Interrogating the Quaternary Structure of Noncanonical Hemoglobin Complexes by Electrospray Mass Spectrometry and Collision-Induced Dissociation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:270-280. [PMID: 33124417 DOI: 10.1021/jasms.0c00320] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Various activation methods are available for the fragmentation of gaseous protein complexes produced by electrospray ionization (ESI). Such experiments can potentially yield insights into quaternary structure. Collision-induced dissociation (CID) is the most widely used fragmentation technique. Unfortunately, CID of protein complexes is dominated by the ejection of highly charged monomers, a process that does not yield any structural insights. Using hemoglobin (Hb) as a model system, this work examines under what conditions CID generates structurally informative subcomplexes. Native ESI mainly produced tetrameric Hb ions. In addition, "noncanonical" hexameric and octameric complexes were observed. CID of all these species [(αβ)2, (αβ)3, and (αβ)4] predominantly generated highly charged monomers. In addition, we observed hexamer → tetramer + dimer dissociation, implying that hexamers have a tetramer··dimer architecture. Similarly, the observation of octamer → two tetramer dissociation revealed that octamers have a tetramer··tetramer composition. Gas-phase candidate structures of Hb assemblies were produced by molecular dynamics (MD) simulations. Ion mobility spectrometry was used to identify the most likely candidates. Our data reveal that the capability of CID to produce structurally informative subcomplexes depends on the fate of protein-protein interfaces after transfer into the gas phase. Collapse of low affinity interfaces conjoins the corresponding subunits and favors CID via monomer ejection. Structurally informative subcomplexes are formed only if low affinity interfaces do not undergo a major collapse. However, even in these favorable cases CID is still dominated by monomer ejection, requiring careful analysis of the experimental data for the identification of structurally informative subcomplexes.
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Affiliation(s)
- Alexander I M Sever
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Victor Yin
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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12
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Wang G, Chaihu L, Tian M, Shao X, Dai R, de Jong RN, Ugurlar D, Gros P, Heck AJR. Releasing Nonperipheral Subunits from Protein Complexes in the Gas Phase. Anal Chem 2020; 92:15799-15805. [DOI: 10.1021/acs.analchem.0c02845] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Guanbo Wang
- School of Chemistry and Materials Science, Nanjing Normal University, 210023 Nanjing, China
| | - Lingxiao Chaihu
- School of Chemistry and Materials Science, Nanjing Normal University, 210023 Nanjing, China
- Institute for Cell Analysis, Shenzhen Bay Laboratory, 518132 Shenzhen, China
| | - Meng Tian
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Xinyang Shao
- Peking-Tsinghua Center for Life Sciences, Peking University, 100871 Beijing, China
| | - Rongrong Dai
- School of Chemistry and Materials Science, Nanjing Normal University, 210023 Nanjing, China
| | | | - Deniz Ugurlar
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Piet Gros
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CH Utrecht, The Netherlands
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13
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Niu C, Yang Y, Huynh A, Nazy I, Kaltashov IA. Platelet Factor 4 Interactions with Short Heparin Oligomers: Implications for Folding and Assembly. Biophys J 2020; 119:1371-1379. [PMID: 32348723 DOI: 10.1016/j.bpj.2020.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 12/11/2022] Open
Abstract
Association of platelet factor 4 (PF4) with heparin is a first step in formation of aggregates implicated in the development of heparin-induced thrombocytopenia (HIT), a potentially fatal immune disorder affecting 1-5% of patients receiving heparin. Despite being a critically important element in HIT etiology, relatively little is known about the specific molecular mechanism of PF4-heparin interactions. This work uses native mass spectrometry to investigate PF4 interactions with relatively short heparin chains (up to decasaccharides). The protein is shown to be remarkably unstable at physiological ionic strength in the absence of polyanions; only monomeric species are observed, and the extent of multiple charging of corresponding ions indicates a partial loss of conformational integrity. The tetramer signal remains at or below the detection threshold in the mass spectra until the solution's ionic strength is elevated well above the physiological level, highlighting the destabilizing role played by electrostatic interactions vis-à-vis quaternary structure of this high-pI protein. The tetramer assembly is dramatically facilitated by relatively short polyanions (synthetic heparin-mimetic pentasaccharide), with the majority of the protein molecules existing in the tetrameric state even at physiological ionic strength. Each tetramer accommodates up to six pentasaccharides, with at least three such ligands required to guarantee the higher-order structure integrity. Similar results are obtained for PF4 association with longer and structurally heterogeneous heparin oligomers (decamers). These longer polyanions can also induce PF4 dimer assembly when bound to the protein in relatively low numbers, lending support to a model of PF4/heparin interaction in which the latter wraps around the protein, making contacts with multiple subunits. Taken together, these results provide a more nuanced picture of PF4-glycosaminoglycan interactions leading to complex formation. This work also advocates for a greater utilization of native mass spectrometry in elucidating molecular mechanisms underlying HIT, as well as other physiological processes driven by electrostatic interactions.
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Affiliation(s)
- Chendi Niu
- Chemistry Department, University of Massachusetts-Amherst, Amherst, Massachusetts
| | - Yang Yang
- Chemistry Department, University of Massachusetts-Amherst, Amherst, Massachusetts
| | - Angela Huynh
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Ishac Nazy
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Igor A Kaltashov
- Chemistry Department, University of Massachusetts-Amherst, Amherst, Massachusetts.
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14
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Brodbelt JS, Morrison LJ, Santos I. Ultraviolet Photodissociation Mass Spectrometry for Analysis of Biological Molecules. Chem Rev 2020; 120:3328-3380. [PMID: 31851501 PMCID: PMC7145764 DOI: 10.1021/acs.chemrev.9b00440] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of new ion-activation/dissociation methods continues to be one of the most active areas of mass spectrometry owing to the broad applications of tandem mass spectrometry in the identification and structural characterization of molecules. This Review will showcase the impact of ultraviolet photodissociation (UVPD) as a frontier strategy for generating informative fragmentation patterns of ions, especially for biological molecules whose complicated structures, subtle modifications, and large sizes often impede molecular characterization. UVPD energizes ions via absorption of high-energy photons, which allows access to new dissociation pathways relative to more conventional ion-activation methods. Applications of UVPD for the analysis of peptides, proteins, lipids, and other classes of biologically relevant molecules are emphasized in this Review.
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Affiliation(s)
- Jennifer S. Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Lindsay J. Morrison
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Inês Santos
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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15
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Han JY, Choi TS, Heo CE, Son MK, Kim HI. Gas-phase conformations of intrinsically disordered proteins and their complexes with ligands: Kinetically trapped states during transfer from solution to the gas phase. MASS SPECTROMETRY REVIEWS 2019; 38:483-500. [PMID: 31021441 DOI: 10.1002/mas.21596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Flexible structures of intrinsically disordered proteins (IDPs) are crucial for versatile functions in living organisms, which involve interaction with diverse partners. Electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) has been widely applied for structural characterization of apo-state and ligand-associated IDPs via two-dimensional separation in the gas phase. Gas-phase IDP structures have been regarded as kinetically trapped states originated from conformational features in solution. However, an implication of the states remains elusive in the structural characterization of IDPs, because it is unclear what structural property of IDPs is preserved. Recent studies have indicated that the conformational features of IDPs in solution are not fully reproduced in the gas phase. Nevertheless, the molecular interactions captured in the gas phase amplify the structural differences between IDP conformers. Therefore, an IDP conformational change that is not observed in solution is observable in the gas-phase structures obtained by ESI-IM-MS. Herein, we have presented up-to-date researches on the key implications of kinetically trapped states in the gas phase with a brief summary of the structural dynamics of IDPs in ESI-IM-MS.
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Affiliation(s)
- Jong Yoon Han
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Tae Su Choi
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093
| | - Chae Eun Heo
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Myung Kook Son
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Hugh I Kim
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
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16
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Danquah BD, Yefremova Y, Opuni KFM, Röwer C, Koy C, Glocker MO. Intact Transition Epitope Mapping - Thermodynamic Weak-force Order (ITEM - TWO). J Proteomics 2019; 212:103572. [PMID: 31683061 DOI: 10.1016/j.jprot.2019.103572] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/25/2019] [Accepted: 10/27/2019] [Indexed: 01/17/2023]
Abstract
We have developed an electrospray mass spectrometry method which is capable to determine antibody affinity in a gas phase experiment. A solution with the immune complex is electrosprayed and multiply charged ions are translated into the gas phase. Then, the intact immune-complex ions are separated from unbound peptide ions. Increasing the voltage difference in a collision cell results in collision induced dissociation of the immune-complex by which bound peptide ions are released. When analyzing a peptide mixture, measuring the mass of the complex-released peptide ions identifies which of the peptides contains the epitope. A step-wise increase in the collision cell voltage difference changes the intensity ratios of the surviving immune complex ions, the released peptide ions, and the antibody ions. From all the ions´ normalized intensity ratios are deduced the thermodynamic quasi equilibrium dissociation constants (KDm0g#) from which are calculated the apparent gas phase Gibbs energies of activation over temperature (ΔGm0g#T). The order of the apparent gas phase dissociation constants of four antibody - epitope peptide pairs matched well with those obtained from in-solution measurements. The determined gas phase values for antibody affinities are independent from the source of the investigated peptides and from the applied instrument. Data are available via ProteomeXchange with identifier PXD016024. SIGNIFICANCE: ITEM - TWO enables rapid epitope mapping and determination of apparent dissociation energies of immune complexes with minimal in-solution handling. Mixing of antibody and antigen peptide solutions initiates immune complex formation in solution. Epitope binding strengths are determined in the gas phase after electrospraying the antibody / antigen peptide mixtures and mass spectrometric analysis of immune complexes under different collision induced dissociation conditions. Since the order of binding strengths in the gas phase is the same as that in solution, ITEM - TWO characterizes two most important antibody properties, specificity and affinity.
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Affiliation(s)
- Bright D Danquah
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | - Yelena Yefremova
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | | | - Claudia Röwer
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | - Cornelia Koy
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | - Michael O Glocker
- Proteome Center Rostock, University Medicine Rostock, Rostock, Germany.
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17
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Danquah BD, Röwer C, Opuni KM, El-Kased R, Frommholz D, Illges H, Koy C, Glocker MO. Intact Transition Epitope Mapping - Targeted High-Energy Rupture of Extracted Epitopes (ITEM-THREE). Mol Cell Proteomics 2019; 18:1543-1555. [PMID: 31147491 PMCID: PMC6683010 DOI: 10.1074/mcp.ra119.001429] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/14/2019] [Indexed: 12/31/2022] Open
Abstract
Epitope mapping, which is the identification of antigenic determinants, is essential for the design of novel antibody-based therapeutics and diagnostic tools. ITEM-THREE is a mass spectrometry-based epitope mapping method that can identify epitopes on antigens upon generating an immune complex in electrospray-compatible solutions by adding an antibody of interest to a mixture of peptides from which at least one holds the antibody's epitope. This mixture is nano-electrosprayed without purification. Identification of the epitope peptide is performed within a mass spectrometer that provides an ion mobility cell sandwiched in-between two collision cells and where this ion manipulation setup is flanked by a quadrupole mass analyzer on one side and a time-of-flight mass analyzer on the other side. In a stepwise fashion, immune-complex ions are separated from unbound peptide ions and dissociated to release epitope peptide ions. Immune complex-released peptide ions are separated from antibody ions and fragmented by collision induced dissociation. Epitope-containing peptide fragment ions are recorded, and mass lists are submitted to unsupervised data base search thereby retrieving both, the amino acid sequence of the epitope peptide and the originating antigen. ITEM-THREE was developed with antiTRIM21 and antiRA33 antibodies for which the epitopes were known, subjecting them to mixtures of synthetic peptides of which one contained the respective epitope. ITEM-THREE was then successfully tested with an enzymatic digest of His-tagged recombinant human β-actin and an antiHis-tag antibody, as well as with an enzymatic digest of recombinant human TNFα and an antiTNFα antibody whose epitope was previously unknown.
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Affiliation(s)
- Bright D Danquah
- ‡Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | - Claudia Röwer
- ‡Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | | | - Reham El-Kased
- ¶Microbiology and Immunology Faculty of Pharmacy, The British University in Egypt, Cairo, Egypt
| | - David Frommholz
- ‖University of Applied Sciences Bonn-Rhein-Sieg, Immunology and Cell Biology, Rheinbach, Germany
| | - Harald Illges
- ‖University of Applied Sciences Bonn-Rhein-Sieg, Immunology and Cell Biology, Rheinbach, Germany;; **University of Applied Sciences Bonn-Rhein-Sieg, Institute for Functional Gene Analytics, Rheinbach, Germany
| | - Cornelia Koy
- ‡Proteome Center Rostock, University Medicine Rostock, Rostock, Germany
| | - Michael O Glocker
- ‡Proteome Center Rostock, University Medicine Rostock, Rostock, Germany.
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18
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Sipe SN, Brodbelt JS. Impact of charge state on 193 nm ultraviolet photodissociation of protein complexes. Phys Chem Chem Phys 2019; 21:9265-9276. [PMID: 31016301 DOI: 10.1039/c9cp01144g] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
As applications in mass spectrometry continue to expand into the field of structural biology, there have been an increasing number of studies on noncovalent biological assemblies. Ensuring that protein complexes maintain native-like conformations and architectures during the transition from solution to the gas phase is a key aim. Probing composition and arrangement of subunits of multi-charged complexes via tandem mass spectrometry (MS/MS) may lead to protein unfolding and the redistribution of charges on the constituent subunits, leading to asymmetric charge partitioning and ejection of a high-charged monomer. Additionally, the overall dissociation efficiency of many ion activation methods is often suppressed for low charge states, hindering the effectiveness of MS/MS for complexes that have low charge density. Ultraviolet photodissociation (UVPD) of proteins using 193 nm photons is a high-energy alternative to collisional activation and demonstrates little to no charge state dependence. Here the symmetry of charge partitioning upon UVPD is evaluated for an array of multimeric protein complexes as a function of initial charge state. The results demonstrate that high laser energies (3 mJ) for UVPD induces more symmetric charge partitioning and ejection of low-charged, presumably compact monomers than higher-energy collisional dissociation (HCD).
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Affiliation(s)
- Sarah N Sipe
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA.
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19
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Donor MT, Mroz AM, Prell JS. Experimental and theoretical investigation of overall energy deposition in surface-induced unfolding of protein ions. Chem Sci 2019; 10:4097-4106. [PMID: 31049192 PMCID: PMC6471915 DOI: 10.1039/c9sc00644c] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 03/06/2019] [Indexed: 12/15/2022] Open
Abstract
Recent advances in native mass spectrometry have enabled its use to probe the structure of and interactions within biomolecular complexes. Surface-induced dissociation, in which inter- and intramolecular interactions are disrupted following an energetic ion-surface collision, is a method that can directly interrogate the topology of protein complexes. However, a quantitative relationship between the ion kinetic energy at the moment of surface collision and the internal energy deposited into the ion has not yet been established for proteins. The factors affecting energy deposition in surface-induced unfolding (SIU) of protein monomers were investigated and a calibration relating laboratory-frame kinetic energy to internal energy developed. Protein monomers were unfolded by SIU and by collision-induced unfolding (CIU). CIU and SIU cause proteins to undergo the same unfolding transitions at different values of laboratory-frame kinetic energy. There is a strong correlation between the SIU and CIU energies, demonstrating that SIU, like CIU, can largely be understood as a thermal process. The change in internal energy in CIU was modeled using a Monte Carlo approach and theory. Computed values of the overall efficiency were found to be approximately 25% and used to rescale the CIU energy axis and relate nominal SIU energies to internal energy. The energy deposition efficiency in SIU increases with mass and kinetic energy from a low of ∼20% to a high of ∼68%, indicating that the effective mass of the surface increases along with the mass of the ion. The effect of ion structure on energy deposition was probed using multiple stages of ion activation. Energy deposition in SIU strongly depends on structure, decreasing as the protein is elongated, due to decreased effective protein-surface collisional cross section and increased transfer to rotational modes.
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Affiliation(s)
- Micah T Donor
- Department of Chemistry and Biochemistry , 1253 University of Oregon , Eugene , OR 97403-1253 , USA
| | - Austin M Mroz
- Department of Chemistry and Biochemistry , 1253 University of Oregon , Eugene , OR 97403-1253 , USA
| | - James S Prell
- Department of Chemistry and Biochemistry , 1253 University of Oregon , Eugene , OR 97403-1253 , USA
- Materials Science Institute , University of Oregon , 1252 University of Oregon , Eugene , OR 97403-1252 , USA . ; ; Tel: +1 541 346 2597
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20
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Root K, Barylyuk K, Schwab A, Thelemann J, Illarionov B, Geist JG, Gräwert T, Bacher A, Fischer M, Diederich F, Zenobi R. Aryl bis-sulfonamides bind to the active site of a homotrimeric isoprenoid biosynthesis enzyme IspF and extract the essential divalent metal cation cofactor. Chem Sci 2018; 9:5976-5986. [PMID: 30079212 PMCID: PMC6050538 DOI: 10.1039/c8sc00814k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 06/17/2018] [Indexed: 12/22/2022] Open
Abstract
Characterizing the mode of action of non-covalent inhibitors in multisubunit enzymes often presents a great challenge. Most of the conventionally used methods are based on ensemble measurements of protein-ligand binding in bulk solution. They often fail to accurately describe multiple binding processes occurring in such systems. Native electrospray ionization mass spectrometry (ESI-MS) of intact protein complexes is a direct, label-free approach that can render the entire distribution of ligand-bound states in multimeric protein complexes. Here we apply native ESI-MS to comprehensively characterize the isoprenoid biosynthesis enzyme IspF from Arabidopsis thaliana, an example of a homomeric protein complex with multiple binding sites for several types of ligands, including a metal cofactor and a synthetic inhibitor. While standard biophysical techniques failed to reveal the mode of action of recently discovered aryl-sulfonamide-based inhibitors of AtIspF, direct native ESI-MS titrations of the protein with the ligands and ligand competition assays allowed us to accurately capture the solution-phase protein-ligand binding equilibria in full complexity and detail. Based on these combined with computational modeling, we propose a mechanism of AtIspF inhibition by aryl bis-sulfonamides that involves both the competition with the substrate for the ligand-binding pocket and the extraction of Zn2+ from the enzyme active site. This inhibition mode is therefore mixed competitive and non-competitive, the latter exerting a key inhibitory effect on the enzyme activity. The results of our study deliver a profound insight into the mechanisms of AtIspF action and inhibition, open new perspectives for designing inhibitors of this important drug target, and demonstrate the applicability and value of the native ESI-MS approach for deep analysis of complex biomolecular binding equilibria.
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Affiliation(s)
- Katharina Root
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Konstantin Barylyuk
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Anatol Schwab
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Jonas Thelemann
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Boris Illarionov
- Hamburg School of Food Science , University of Hamburg , Hamburg , Germany
| | - Julie G Geist
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Tobias Gräwert
- Hamburg School of Food Science , University of Hamburg , Hamburg , Germany
| | - Adelbert Bacher
- Department of Chemistry , Technical University of Munich , Garching , Germany
| | - Markus Fischer
- Hamburg School of Food Science , University of Hamburg , Hamburg , Germany
| | - François Diederich
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
| | - Renato Zenobi
- Department of Chemistry and Applied Biosciences , ETH Zurich , Zurich , Switzerland .
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21
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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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22
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Konermann L, Metwally H, McAllister RG, Popa V. How to run molecular dynamics simulations on electrospray droplets and gas phase proteins: Basic guidelines and selected applications. Methods 2018; 144:104-112. [DOI: 10.1016/j.ymeth.2018.04.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/10/2018] [Accepted: 04/12/2018] [Indexed: 12/13/2022] Open
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23
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How can native mass spectrometry contribute to characterization of biomacromolecular higher-order structure and interactions? Methods 2018; 144:3-13. [PMID: 29704661 DOI: 10.1016/j.ymeth.2018.04.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/03/2018] [Accepted: 04/21/2018] [Indexed: 01/16/2023] Open
Abstract
Native mass spectrometry (MS) is an emerging approach for characterizing biomacromolecular structure and interactions under physiologically relevant conditions. In native MS measurement, intact macromolecules or macromolecular complexes are directly ionized from a non-denaturing solvent, and key noncovalent interactions that hold the complexes together can be preserved for MS analysis in the gas phase. This technique provides unique multi-level structural information such as conformational changes, stoichiometry, topology and dynamics, complementing conventional biophysical techniques. Despite the maturation of native MS and greatly expanded range of applications in recent decades, further dissemination is needed to make the community aware of such a technique. In this review, we attempt to provide an overview of the current body of knowledge regarding major aspects of native MS and explain how such technique contributes to the characterization of biomacromolecular higher-order structure and interactions.
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24
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Wang G, Bondarenko PV, Kaltashov IA. Multi-step conformational transitions in heat-treated protein therapeutics can be monitored in real time with temperature-controlled electrospray ionization mass spectrometry. Analyst 2018; 143:670-677. [PMID: 29303166 DOI: 10.1039/c7an01655g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heat-induced conformational transitions are frequently used to probe the free energy landscapes of proteins. However, the extraction of information from thermal denaturation profiles pertaining to non-native protein conformations remains challenging due to their transient nature and significant conformational heterogeneity. Previously we developed a temperature-controlled electrospray ionization (ESI) source that allowed unfolding and association of biopolymers to be monitored by mass spectrometry (MS) in real time as a function of temperature. The scope of this technique is now extended to systems that undergo multi-step denaturation upon heat stress, as well as relatively small-scale conformational changes that are precursors to protein aggregation. The behavior of two therapeutic proteins (human antithrombin and an IgG1 monoclonal antibody) under heat-stress conditions is monitored in real time, providing evidence that relatively small-scale conformational changes in each system lead to protein oligomerization, followed by aggregation. Temperature-controlled ESI MS is particularly useful for the studies of heat-stressed multi-domain proteins such as IgG, where it allows distinct transitions to be observed. The ability of native temperature-controlled ESI MS to monitor both the conformational changes and oligomerization/degradation with high selectivity complements the classic calorimetric methods, lending itself as a powerful experimental tool for the thermostability studies of protein therapeutics.
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Affiliation(s)
- Guanbo Wang
- Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, and School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu, China.
| | - Pavel V Bondarenko
- Attribute Sciences, Process Development, Amgen, Inc., Thousand Oaks, CA, USA
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
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25
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Yefremova Y, Danquah BD, Opuni KF, El-Kased R, Koy C, Glocker MO. Mass spectrometric characterization of protein structures and protein complexes in condensed and gas phase. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2017; 23:445-459. [PMID: 29183193 DOI: 10.1177/1469066717722256] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Proteins are essential for almost all physiological processes of life. They serve a myriad of functions which are as varied as their unique amino acid sequences and their corresponding three-dimensional structures. To fulfill their tasks, most proteins depend on stable physical associations, in the form of protein complexes that evolved between themselves and other proteins. In solution (condensed phase), proteins and/or protein complexes are in constant energy exchange with the surrounding solvent. Albeit methods to describe in-solution thermodynamic properties of proteins and of protein complexes are well established and broadly applied, they do not provide a broad enough access to life-science experimentalists to study all their proteins' properties at leisure. This leaves great desire to add novel methods to the analytical biochemist's toolbox. The development of electrospray ionization created the opportunity to characterize protein higher order structures and protein complexes rather elegantly by simultaneously lessening the need of sophisticated sample preparation steps. Electrospray mass spectrometry enabled us to translate proteins and protein complexes very efficiently into the gas phase under mild conditions, retaining both, intact protein complexes, and gross protein structures upon phase transition. Moreover, in the environment of the mass spectrometer (gas phase, in vacuo), analyte molecules are free of interactions with surrounding solvent molecules and, therefore, the energy of inter- and intramolecular forces can be studied independently from interference of the solvating environment. Provided that gas phase methods can give information which is relevant for understanding in-solution processes, gas phase protein structure studies and/or investigations on the characterization of protein complexes has rapidly gained more and more attention from the bioanalytical scientific community. Recent reports have shown that electrospray mass spectrometry provides direct access to six prime protein complex properties: stabilities, compositions, binding surfaces (epitopes), disassembly processes, stoichiometries, and thermodynamic parameters.
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Affiliation(s)
- Yelena Yefremova
- 1 Proteome Center Rostock, University of Rostock, Rostock, Germany
| | - Bright D Danquah
- 1 Proteome Center Rostock, University of Rostock, Rostock, Germany
| | | | - Reham El-Kased
- 3 Microbiology and Immunology, Faculty of Pharmacy, The British University in Egypt, Cairo, Egypt
| | - Cornelia Koy
- 1 Proteome Center Rostock, University of Rostock, Rostock, Germany
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26
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Skinner OS, McAnally MO, Van Duyne RP, Schatz GC, Breuker K, Compton PD, Kelleher NL. Native Electron Capture Dissociation Maps to Iron-Binding Channels in Horse Spleen Ferritin. Anal Chem 2017; 89:10711-10716. [PMID: 28938074 PMCID: PMC5647560 DOI: 10.1021/acs.analchem.7b01581] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
Native electron capture
dissociation (NECD) is a process during
which proteins undergo fragmentation similar to that from radical
dissociation methods, but without the addition of exogenous electrons.
However, after three initial reports of NECD from the cytochrome c dimer complex, no further evidence of the effect has been
published. Here, we report NECD behavior from horse spleen ferritin,
a ∼490 kDa protein complex ∼20-fold larger than the
previously studied cytochrome c dimer. Application
of front-end infrared excitation (FIRE) in conjunction with low- and
high-m/z quadrupole isolation and
collisionally activated dissociation (CAD) provides new insights into
the NECD mechanism. Additionally, activation of the intact complex
in either the electrospray droplet or the gas phase produced c-type fragment ions. Similar to the previously reported
results on cytochrome c, these fragment ions form
near residues known to interact with iron atoms in solution. By mapping
the location of backbone cleavages associated with c-type ions onto
the crystal structure, we are able to characterize two distinct iron
binding channels that facilitate iron ion transport into the core
of the complex. The resulting pathways are in good agreement with
previously reported results for iron binding sites in mammalian ferritin.
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Affiliation(s)
- Owen S Skinner
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Michael O McAnally
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Richard P Van Duyne
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - George C Schatz
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Kathrin Breuker
- Institute of Organic Chemistry, University of Innsbruck , A-6020 Innsbruck, Austria
| | - Philip D Compton
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Neil L Kelleher
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
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27
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Yefremova Y, Melder FTI, Danquah BD, Opuni KFM, Koy C, Ehrens A, Frommholz D, Illges H, Koelbel K, Sobott F, Glocker MO. Apparent activation energies of protein-protein complex dissociation in the gas-phase determined by electrospray mass spectrometry. Anal Bioanal Chem 2017; 409:6549-6558. [PMID: 28900708 DOI: 10.1007/s00216-017-0603-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/09/2017] [Accepted: 08/23/2017] [Indexed: 11/30/2022]
Abstract
We have developed a method to determine apparent activation energies of dissociation for ionized protein-protein complexes in the gas phase using electrospray ionization mass spectrometry following the Rice-Ramsperger-Kassel-Marcus quasi-equilibrium theory. Protein-protein complexes were formed in solution, transferred into the gas phase, and separated from excess free protein by ion mobility filtering. Afterwards, complex disassembly was initiated by collision-induced dissociation with step-wise increasing energies. Relative intensities of ion signals were used to calculate apparent activation energies of dissociation in the gas phase by applying linear free energy relations. The method was developed using streptavidin tetramers. Experimentally determined apparent gas-phase activation energies for dissociation ([Formula: see text]) of complexes consisting of Fc parts from immunoglobulins (IgG-Fc) and three closely related protein G' variants (IgG-Fc•protein G'e, IgG-Fc•protein G'f, and IgG-Fc•protein G'g) show the same order of stabilities as can be inferred from their in-solution binding constants. Differences in stabilities between the protein-protein complexes correspond to single amino acid residue exchanges in the IgG-binding regions of the protein G' variants. Graphical abstract Electrospray mass spectrometry and collision-induced dissociation delivers apparent activation energies and supramolecular bond force constants of protein-protein complexes in the gas phase.
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Affiliation(s)
- Yelena Yefremova
- Proteome Center Rostock, University Rostock Medical Center, Schillingallee 69, 18059, Rostock, Germany
| | - F Teresa I Melder
- Proteome Center Rostock, University Rostock Medical Center, Schillingallee 69, 18059, Rostock, Germany
| | - Bright D Danquah
- Proteome Center Rostock, University Rostock Medical Center, Schillingallee 69, 18059, Rostock, Germany
| | - Kwabena F M Opuni
- Proteome Center Rostock, University Rostock Medical Center, Schillingallee 69, 18059, Rostock, Germany.,School of Pharmacy, University of Ghana, P.O. Box LG43, Legon Accra, Ghana
| | - Cornelia Koy
- Proteome Center Rostock, University Rostock Medical Center, Schillingallee 69, 18059, Rostock, Germany
| | - Alexandra Ehrens
- University of Applied Sciences Bonn-Rhein-Sieg, von-Liebig-Str. 20, 53359, Rheinbach, Germany.,University Hospital of Bonn, Sigmung-Freud-Str. 25, 53105, Bonn, Germany
| | - David Frommholz
- University of Applied Sciences Bonn-Rhein-Sieg, von-Liebig-Str. 20, 53359, Rheinbach, Germany
| | - Harald Illges
- University of Applied Sciences Bonn-Rhein-Sieg, von-Liebig-Str. 20, 53359, Rheinbach, Germany
| | - Knut Koelbel
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - Frank Sobott
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.,School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Michael O Glocker
- Proteome Center Rostock, University Rostock Medical Center, Schillingallee 69, 18059, Rostock, Germany.
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28
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Laszlo KJ, Bush MF. Interpreting the Collision Cross Sections of Native-like Protein Ions: Insights from Cation-to-Anion Proton-Transfer Reactions. Anal Chem 2017. [PMID: 28636334 DOI: 10.1021/acs.analchem.7b01474] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The effects of charge state on structures of native-like cations of serum albumin, streptavidin, avidin, and alcohol dehydrogenase were probed using cation-to-anion proton-transfer reactions (CAPTR), ion mobility, mass spectrometry, and complementary energy-dependent experiments. The CAPTR products all have collision cross-section (Ω) values that are within 5.5% of the original precursor cations. The first CAPTR event for each precursor yields products that have smaller Ω values and frequently exhibit the greatest magnitude of change in Ω resulting from a single CAPTR event. To investigate how the structures of the precursors affect the structures of the products, ions were activated as a function of energy prior to CAPTR. In each case, the Ω values of the activated precursors increase with increasing energy, but the Ω values of the CAPTR products are smaller than the activated precursors. To investigate the stabilities of the CAPTR products, the products were activated immediately prior to ion mobility. These results show that additional structures with smaller or larger Ω values can be populated and that the structures and stabilities of these ions depend most strongly on the identity of the protein and the charge state of the product, rather than the charge state of the precursor or the number of CAPTR events. Together, these results indicate that the excess charges initially present on native-like ions have a modest, but sometimes statistically significant, effect on their Ω values. Therefore, potential contributions from charge state should be considered when using experimental Ω values to elucidate structures in solution.
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Affiliation(s)
- Kenneth J Laszlo
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Matthew F Bush
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
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29
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Harvey SR, Liu Y, Liu W, Wysocki VH, Laganowsky A. Surface induced dissociation as a tool to study membrane protein complexes. Chem Commun (Camb) 2017; 53:3106-3109. [PMID: 28243658 PMCID: PMC5445643 DOI: 10.1039/c6cc09606a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Native ion mobility mass spectrometry (MS) and surface induced dissociation (SID) are applied to study the integral membrane protein complexes AmtB and AqpZ. Fragments produced from SID are consistent with the solved structures of these complexes. SID is, therefore, a promising tool for characterization of membrane protein complexes.
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Affiliation(s)
- Sophie R Harvey
- The Department of Chemistry and Biochemistry, The Ohio State University, 460 W 12th Avenue, Columbus, Ohio 43210, USA. and School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, M1 7DN, UK
| | - Yang Liu
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA.
| | - Wen Liu
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA.
| | - Vicki H Wysocki
- The Department of Chemistry and Biochemistry, The Ohio State University, 460 W 12th Avenue, Columbus, Ohio 43210, USA.
| | - Arthur Laganowsky
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA. and Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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30
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Xu S, Kaltashov IA. Evaluation of Gallium as a Tracer of Exogenous Hemoglobin-Haptoglobin Complexes for Targeted Drug Delivery Applications. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:2025-2032. [PMID: 27619921 DOI: 10.1007/s13361-016-1484-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 08/15/2016] [Accepted: 08/16/2016] [Indexed: 06/06/2023]
Abstract
Haptoglobin (Hp) is a plasma glycoprotein that generates significant interest in the drug delivery community because of its potential for delivery of antiretroviral medicines with high selectivity to macrophages and monocytes, the latent reservoirs of human immunodeficiency virus. As is the case with other therapies that exploit transport networks for targeted drug delivery, the success of the design and optimization of Hp-based therapies will critically depend on the ability to accurately localize and quantitate Hp-drug conjugates on the varying and unpredictable background of endogenous proteins having identical structure. In this work, we introduce a new strategy for detecting and quantitating exogenous Hp and Hp-based drugs with high sensitivity in complex biological samples using gallium as a tracer of this protein and inductively coupled plasma mass spectrometry (ICP MS) as a method of detection. Metal label is introduced by reconstituting hemoglobin (Hb) with gallium(III)-protoporphyrin IX followed by its complexation with Hp. Formation of the Hp/Hb assembly and its stability are evaluated with native electrospray ionization mass spectrometry. Both stable isotopes of Ga give rise to an abundant signal in ICP MS of a human plasma sample spiked with the metal-labeled Hp/Hb complex. The metal label signal exceeds the spectral interferences' contributions by more than an order of magnitude even with the concentration of the exogenous protein below 10 nM, the level that is more than adequate for the planned pharmacokinetic studies of Hp-based therapeutics. Graphical Abstract ᅟ.
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Affiliation(s)
- Shengsheng Xu
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA.
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31
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Tamara S, Dyachenko A, Fort KL, Makarov AA, Scheltema RA, Heck AJR. Symmetry of Charge Partitioning in Collisional and UV Photon-Induced Dissociation of Protein Assemblies. J Am Chem Soc 2016; 138:10860-8. [PMID: 27480281 PMCID: PMC6392339 DOI: 10.1021/jacs.6b05147] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Indexed: 01/08/2023]
Abstract
Tandem mass spectrometry can provide structural information on intact protein assemblies, generating mass fingerprints indicative of the stoichiometry and quaternary arrangement of the subunits. However, in such experiments, collision-induced dissociation yields restricted information due to simultaneous subunit unfolding, charge rearrangement, and subsequent ejection of a highly charged unfolded single subunit. Alternative fragmentation strategies can potentially overcome this and supply a deeper level of structural detail. Here, we implemented ultraviolet photodissociation (UVPD) on an Orbitrap mass spectrometer optimized for native MS and benchmark its performance to HCD fragmentation using various protein oligomers. We investigated dimeric β-lactoglobulin, dimeric superoxide dismutase, dimeric and tetrameric concanavalin A, and heptameric GroES and Gp31; ranging in molecular weight from 32 to 102 kDa. We find that, for the investigated systems, UVPD produces more symmetric charge partitioning than HCD. While HCD spectra show sporadic fragmentation over the full protein backbone sequence of the subunits with a bias toward fragmenting labile bonds, UVPD spectra provided higher sequence coverage. Taken together, we conclude that UVPD is a strong addition to the toolbox of fragmentation methods for top-down proteomics experiments, especially for native protein assemblies.
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Affiliation(s)
- Sem Tamara
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Andrey Dyachenko
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Kyle L. Fort
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Alexander A. Makarov
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
- Thermo
Fisher Scientific (Bremen), 28199 Bremen, Germany
| | - Richard A. Scheltema
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular
Mass Spectrometry and Proteomics, Bijvoet Center for
Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, and Netherlands
Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands
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32
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Morrison LJ, Brodbelt JS. 193 nm Ultraviolet Photodissociation Mass Spectrometry of Tetrameric Protein Complexes Provides Insight into Quaternary and Secondary Protein Topology. J Am Chem Soc 2016; 138:10849-59. [PMID: 27480400 DOI: 10.1021/jacs.6b03905] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein-protein interfaces and architecture are critical to the function of multiprotein complexes. Mass spectrometry-based techniques have emerged as powerful strategies for characterization of protein complexes, particularly for heterogeneous mixtures of structures. In the present study, activation and dissociation of three tetrameric protein complexes (streptavidin, transthyretin, and hemoglobin) in the gas phase was undertaken by 193 nm ultraviolet photodissociation (UVPD) for the characterization of higher order structure. High pulse energy UVPD resulted in the production of dimers and low charged monomers exhibiting symmetrical charge partitioning among the subunits (the so-called symmetrical dissociation pathways), consistent with the subunit organization of the complexes. In addition, UVPD promoted backbone cleavages of the monomeric subunits, the abundances of which corresponded to the more flexible loop regions of the proteins.
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Affiliation(s)
- Lindsay J Morrison
- Department of Chemistry, University of Texas , Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas , Austin, Texas 78712, United States
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33
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Thachuk M, Fegan SK, Raheem N. Description and control of dissociation channels in gas-phase protein complexes. J Chem Phys 2016. [DOI: 10.1063/1.4960615] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mark Thachuk
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Sarah K. Fegan
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Nigare Raheem
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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34
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Popa V, Trecroce DA, McAllister RG, Konermann L. Collision-Induced Dissociation of Electrosprayed Protein Complexes: An All-Atom Molecular Dynamics Model with Mobile Protons. J Phys Chem B 2016; 120:5114-24. [DOI: 10.1021/acs.jpcb.6b03035] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Vlad Popa
- Department
of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Danielle A. Trecroce
- Department
of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Robert G. McAllister
- Department
of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Lars Konermann
- Department
of Biochemistry, The University of Western Ontario, London, ON N6A 5C1, Canada
- Department
of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
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35
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Compton PD, Fornelli L, Kelleher NL, Skinner OS. Probing Asymmetric Charge Partitioning of Protein Oligomers during Tandem Mass Spectrometry. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2015; 390:132-136. [PMID: 26692813 PMCID: PMC4673687 DOI: 10.1016/j.ijms.2015.08.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Dissociation of gaseous protein complexes produced by native electrospray often induces an asymmetric partitioning of charge between ejected subunits. We present a simple asymmetric charge partitioning factor (ACPF) to quantify the magnitude of asymmetry in this effect. When applied to monomer ejection from the cytochrome c dimer and β-amylase tetramer, we found that the ~60-70% of precursor charge ending up in the ejected monomers corresponds to ACPFs of 1.38 and 2.51, respectively. Further, we used site-specific fragmentation from electron transfer dissociation (ETD) to identify differences in fragmentation and characterize domains of secondary-structure present in the dimer, ejected monomers, and monomers obtained directly from electrospray ionization (ESI). We found evidence of structural changes between the dimer and ejected monomer, but also that the ejected monomer had a nearly identical set of fragment ions produced by ETD as the ESI monomer with the same charge state. Surprisingly, APCF values for ETD fragment ions generated directly from the dimer revealed that the fragments undergo asymmetric charge partitioning at over twice the magnitude of that observed for ejection of the monomer.
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Affiliation(s)
- Philip D. Compton
- Departments of Chemistry and Molecular Biosciences and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, USA
| | - Luca Fornelli
- Departments of Chemistry and Molecular Biosciences and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, USA
| | - Neil L. Kelleher
- Departments of Chemistry and Molecular Biosciences and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, USA
| | - Owen S. Skinner
- Departments of Chemistry and Molecular Biosciences and the Proteomics Center of Excellence, Northwestern University, Evanston, Illinois 60208, USA
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36
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Cui W, Zhang H, Blankenship RE, Gross ML. Electron-capture dissociation and ion mobility mass spectrometry for characterization of the hemoglobin protein assembly. Protein Sci 2015; 24:1325-32. [PMID: 26032343 DOI: 10.1002/pro.2712] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 05/19/2015] [Indexed: 12/12/2022]
Abstract
Native spray has the potential to probe biophysical properties of protein assemblies. Here we report an investigation using both ECD top-down sequencing with an FTICR mass spectrometer and ion mobility (IM) measurements on a Q-TOF to investigate the collisionally induced unfolding of a native-like heterogeneous tetrameric assembly, human hemoglobin (hHb), in the gas phase. To our knowledge, this is the first report combining ECD and ion-mobility data on the same target protein assembly to delineate the effects of collisional activation on both assembly size and the extent and location of fragmentation. Although the collision-induced unfolding of the hemoglobin assembly is clearly seen by both IMMS and ECD, the latter delineates the regions that increasingly unfold as the collision energy is increased. The results are consistent with previous outcomes for homogeneous protein assemblies and reinforce our interpretation that activation opens the structure of the protein assembly from the flexible regions to make available ECD fragmentation, without dissociating the component proteins.
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Affiliation(s)
- Weidong Cui
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, 63130
| | - Hao Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, 63130
| | - Robert E Blankenship
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, 63130.,Department of Biology, Washington University in St. Louis, St. Louis, Missouri, 63130
| | - Michael L Gross
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, 63130
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37
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Larriba C, Fernandez de la Mora J, Clemmer DE. Electrospray ionization mechanisms for large polyethylene glycol chains studied through tandem ion mobility spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1332-1345. [PMID: 24924517 DOI: 10.1007/s13361-014-0885-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 03/02/2014] [Accepted: 03/03/2014] [Indexed: 06/03/2023]
Abstract
Ion mobility mass spectrometry (IMS-MS) is used to investigate the abundance pattern, n(z)(m) of poly-(ethyleneglycol) (PEG) electrosprayed from water/methanol as a function of mass and charge state. We examine n(z)(m) patterns from a diversity of solution cations, primarily dimethylammonium and triethylammonium. The ability of PEG chains to initially attach to various cations in the spraying chamber, and to retain them (or not) on entering the MS, provide valuable clues on the ionization mechanism. Single chains form in highly charged and extended shapes in most buffers. But the high initial charge they hold under atmospheric pressure is lost on transit to the vacuum system for large cations. In contrast, aggregates of two or more chains carry in all buffers at most the Rayleigh charge of a water drop of the same volume. This shows either that they form via Dole's charge residue mechanism, or that highly charged and extended aggregates are ripped apart by Coulombic repulsion. IMS-IMS experiments in He confirm these findings, and provide new mechanistic insights on the stability of aggregates. When collisionally activated, initially globular dimers are stable. However, slightly nonglobular dimers projecting out a linear appendix are segregated into two monomeric chains. The breakup of a charged dimer is therefore a multi-step process, similar to the Fenn-Consta polymer extrusion mechanism. The highest activation barrier is associated to the first step, where a short chain segment carrying a single charge escapes (ion-evaporates) from a charged drop, leading then to gradual field extrusion of the whole chain out of the drop.
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Affiliation(s)
- Carlos Larriba
- Mechanical Engineering Department, Yale University, New Haven, CT, 06520, USA,
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38
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Fegan SK, Thachuk M. Controlling dissociation channels of gas-phase protein complexes using charge manipulation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:722-728. [PMID: 24526466 DOI: 10.1007/s13361-014-0831-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/20/2013] [Accepted: 01/18/2014] [Indexed: 06/03/2023]
Abstract
Coarse-grained simulations with charge hopping were performed for a positively charged tetrameric transthyretin (TTR) protein complex with a total charge of +20. Charges were allowed to move among basic amino acid sites as well as N-termini. Charge distributions and radii of gyration were calculated for complexes simulated at two temperatures, 300 and 600 K, under different scenarios. One scenario treated the complex in its normal state allowing charge to move to any basic site. Another scenario blocked protonation of all the N-termini except one. A final scenario used the complex in its normal state but added a basic-site containing tether (charge tag) near the N-terminus of one chain. The differences in monomer unfolding and charging were monitored in all three scenarios and compared. The simulation results show the importance of the N-terminus in leading the unfolding of the monomer units; a process that follows a zipper-like mechanism. Overall, experimentally modifying the complex by adding a tether or blocking the protonation of N-termini may give the potential for controlling the unraveling and subsequent dissociation of protein complexes.
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Affiliation(s)
- Sarah K Fegan
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
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39
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Zhou M, Wysocki VH. Surface induced dissociation: dissecting noncovalent protein complexes in the gas phase. Acc Chem Res 2014; 47:1010-8. [PMID: 24524650 DOI: 10.1021/ar400223t] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The quaternary structures of proteins are both important and of interest to chemists, because many proteins exist as complexes in vivo, and probing these structures allows us to better understand their biological functions. Conventional structural biology methods such as X-ray crystallography and nuclear magnetic resonance provide high-resolution information on the structures of protein complexes and are the gold standards in the field. However, other emerging biophysical methods that only provide low-resolution data (e.g. stoichiometry and subunit connectivity) on the structures of the protein complexes are also becoming more important to scientists. Mass spectrometry is one of these approaches that provide lower than atomic structural resolution, but the approach is higher throughput and provides not only better mass information than other techniques but also stoichiometry and topology. Fragile noncovalent interactions within the protein complexes can be preserved in the gas phase of MS under gentle ionization and transfer conditions. Scientists can measure the masses of the complexes with high confidence to reveal the stoichiometry and composition of the proteins. What makes mass spectrometry an even more powerful method is that researchers can further isolate the protein complexes and activate them in the gas phase to release subunits for more structural information. The caveat is that, upon gas-phase activation, the released subunits need to faithfully reflect the native topology so that useful information on the proteins can be extracted from mass spectrometry experiments. Unfortunately, many proteins tend to favor unfolding upon collision with neutral gas (the most common activation method in mass spectrometers). Therefore, this typically results in limited insights on the quaternary structure of the precursor without further manipulation of other experimental factors. Scientists have observed, however, that valuable structural information can be obtained when the gas-phase proteins are activated by collision with a surface. Subcomplexes released after surface collision are consistent with the native quaternary structure of several protein systems studied, even for a large chaperone protein, GroEL, that approaches megadalton mass. The unique and meaningful data generated from surface induced dissociation (SID) have been attributed to the fast and energetic activation process upon collision with a massive target, the surface. In this Account, we summarize our SID studies of protein complexes, with emphasis on the more recent work on the combination of ion mobility (IM) with SID. IM has gained popularity over the years not only as a gas-phase separation technique but also as a technique with the ability to measure the size and shape of the proteins in the gas phase. Incorporation of IM before SID allows different conformations of a protein to be separated and examined individually by SID for structural details. When IM is after SID, the cross sections of the SID products can be measured, providing insight on the dissociation pathways, which may mimic disassembly pathways. Furthermore, the separation by IM greatly reduces the peak overlapping (same m/z) and coalescence (merging) of SID products, improving the resolving power of the method. While there are still many unanswered questions on the fundamental properties of gas-phase proteins and a need for further research, our work has shown that SID can be a complementary gas-phase tool providing useful information for studying quaternary structures of noncovalent protein complexes.
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Affiliation(s)
- Mowei Zhou
- Department of Chemistry and
Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210, United States
| | - Vicki H. Wysocki
- Department of Chemistry and
Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210, United States
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40
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Liu J, Konermann L. Cation-induced stabilization of protein complexes in the gas phase: mechanistic insights from hemoglobin dissociation studies. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:595-603. [PMID: 24452299 DOI: 10.1007/s13361-013-0814-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 12/13/2013] [Accepted: 12/14/2013] [Indexed: 06/03/2023]
Abstract
Collision-induced dissociation (CID) of electrosprayed protein complexes usually involves asymmetric charge partitioning, where a single unfolded chain gets ejected that carries a disproportionately large fraction of charge. Using hemoglobin (Hb) tetramers as model system, we confirm earlier reports that bound metal ions can stabilize protein complexes under CID conditions. We examine the mechanism underlying this effect. Nonvolatile salts cause extensive adduct formation. Significant stabilization was observed for Mg(2+) and Ca(2+), whereas K(+), Rb(+), and Cs(+) had no effect. Precursor ion selection was used to examine Hb subpopulations with well-defined metal binding levels. K(+), Rb(+), and Cs(+)-adducted tetramers eject monomers that carry roughly one-quarter of the metal ions that were bound to the precursor. This demonstrates that charge migration during CID is exclusively due to proton transfer, not metal ion transfer. Also, replacement of highly mobile charge carriers (protons) with less mobile species (metal ions) does not exert a stabilizing influence under the conditions used here. Interestingly, Hb carrying stabilizing ions (Mg(2+) and Ca(2+)) generates monomeric CID products that are metal depleted. This effect is attributed to a combination of two factors: (1) Me(2+) binding stabilizes Hb via formation of chelation bridges (e.g., R-COO(-) Me(2+) (-)OOC-R); the more Me(2+) a subunit contains the more stable it is. (2) More than ~90% of the tetramers contain at least one subunit with a below-average number of Me(2+). The prevalence of monomeric CID products with depleted Me(2+) levels is caused by the tendency of these low metal-containing subunits to undergo preferential unfolding/ejection.
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Affiliation(s)
- JiangJiang Liu
- Department of Chemistry, The University of Western Ontario, London, ON, N6A 5B7, Canada
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41
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Konermann L, Vahidi S, Sowole MA. Mass Spectrometry Methods for Studying Structure and Dynamics of Biological Macromolecules. Anal Chem 2013; 86:213-32. [DOI: 10.1021/ac4039306] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
| | - Siavash Vahidi
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
| | - Modupeola A. Sowole
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
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42
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Zhou M, Jones CM, Wysocki VH. Dissecting the Large Noncovalent Protein Complex GroEL with Surface-Induced Dissociation and Ion Mobility–Mass Spectrometry. Anal Chem 2013; 85:8262-7. [DOI: 10.1021/ac401497c] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Mowei Zhou
- Department of Chemistry
and Biochemistry, Ohio State University, 484 W. 12th Ave., Columbus, Ohio 43210, United States
- Department of Chemistry
and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Christopher M. Jones
- Department of Chemistry
and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
| | - Vicki H. Wysocki
- Department of Chemistry
and Biochemistry, Ohio State University, 484 W. 12th Ave., Columbus, Ohio 43210, United States
- Department of Chemistry
and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721, United States
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43
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Santambrogio C, Favretto F, D'Onofrio M, Assfalg M, Grandori R, Molinari H. Mass spectrometry and NMR analysis of ligand binding by human liver fatty acid binding protein. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:895-903. [PMID: 23893635 DOI: 10.1002/jms.3237] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/10/2013] [Accepted: 05/16/2013] [Indexed: 06/02/2023]
Abstract
Human liver fatty acid binding protein (hL-FABP) is the most abundant cytosolic protein in the liver. This protein plays important roles associated to partitioning of fatty acids (FAs) to specific metabolic pathways, nuclear signaling and protection against oxidative damage. The protein displays promiscuous binding properties and can bind two internal ligands, unlike FABPs from other tissues. Different topologies for the ligand located in the more accessible site have been reported, with either a 'head-in' or 'head-out' orientation of the carboxylate end. Electrospray-ionization mass spectrometry and nuclear magnetic resonance titrations are employed here in order to investigate in further detail the binding properties of this system, the equilibria established in solution and the pH dependence of the complexes. The results are consistent with two binding sites with different affinity and a unique head-out topology for the second molecule of either ligand. Competition experiments indicate a higher affinity for oleic acid relative to palmitic acid at each binding site.
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Affiliation(s)
- C Santambrogio
- Department of Biotechnology and Biosciences, Piazza della Scienza 2, University of Milano-Bicocca, 20126, Milan, Italy
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44
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Sowole MA, Konermann L. Comparative analysis of oxy-hemoglobin and aquomet-hemoglobin by hydrogen/deuterium exchange mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:997-1005. [PMID: 23666601 DOI: 10.1007/s13361-013-0647-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 04/12/2013] [Accepted: 04/14/2013] [Indexed: 06/02/2023]
Abstract
The function of hemoglobin (Hb) as oxygen transporter is mediated by reversible O2 binding to Fe(2+) heme in each of the α and β subunits. X-ray crystallography revealed different subunit arrangements in oxy-Hb and deoxy-Hb. The deoxy state is stabilized by additional contacts, causing a rigidification that results in strong protection against hydrogen/deuterium exchange (HDX). Aquomet-Hb is a dysfunctional degradation product with four water-bound Fe(3+) centers. Heme release from aquomet-Hb is relatively facile, triggering oxidative damage of membrane lipids. Aquomet-Hb crystallizes in virtually the same conformation as oxy-Hb. Hence, it is commonly implied that the solution-phase properties of aquomet-Hb should resemble those of the oxy state. This work compares the structural dynamics of oxy-Hb and aquomet-Hb by HDX mass spectrometry (MS). It is found that the aquomet state exhibits a solution-phase structure that is significantly more dynamic, as manifested by elevated HDX levels. These enhanced dynamics affect the aquomet α and β subunits in a different fashion. The latter undergoes global destabilization, whereas the former shows elevated HDX levels only in the heme binding region. It is proposed that these enhanced dynamics play a role in facilitating heme release from aquomet-Hb. Our findings should be of particular interest to the MS community because oxy-Hb and aquomet-Hb serve as widely used test analytes for probing the relationship between biomolecular structure in solution and in the gas phase. We are not aware of any prior comparative HDX/MS experiments on oxy-Hb and aquomet-Hb.
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Affiliation(s)
- Modupeola A Sowole
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada
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45
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Fegan SK, Thachuk M. A Charge Moving Algorithm for Molecular Dynamics Simulations of Gas-Phase Proteins. J Chem Theory Comput 2013; 9:2531-9. [DOI: 10.1021/ct300906a] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sarah K. Fegan
- Department of Chemistry, University
of British Columbia,
2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
| | - Mark Thachuk
- Department of Chemistry, University
of British Columbia,
2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
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46
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Kükrer B, Barbu IM, Copps J, Hogan P, Taylor SS, van Duijn E, Heck AJR. Conformational isomers of calcineurin follow distinct dissociation pathways. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1534-43. [PMID: 22811075 PMCID: PMC4120237 DOI: 10.1007/s13361-012-0441-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/28/2012] [Accepted: 06/28/2012] [Indexed: 05/12/2023]
Abstract
In the gas-phase, ions of protein complexes typically follow an asymmetric dissociation pathway upon collisional activation, whereby an expelled small monomer takes a disproportionately large amount of the charges from the precursor ion. This phenomenon has been rationalized by assuming that upon activation, a single monomer becomes unfolded, thereby attracting charges to its newly exposed basic residues. Here, we report on the atypical gas-phase dissociation of the therapeutically important, heterodimeric calcium/calmodulin-dependent serine/threonine phosphatase calcineurin, using a combination of tandem mass spectrometry, ion mobility mass spectrometry, and computational modeling. Therefore, a hetero-dimeric calcineurin construct (62 kDa), composed of CNa (44 kDa, a truncation mutant missing the calmodulin binding and auto-inhibitory domains), and CNb (18 kDa), was used. Upon collisional activation, this hetero-dimer follows the commonly observed dissociation behavior, whereby the smaller CNb becomes highly charged and is expelled. Surprisingly, in addition, a second atypical dissociation pathway, whereby the charge partitioning over the two entities is more symmetric is observed. The presence of two gas-phase conformational isomers of calcineurin as revealed by ion mobility mass spectrometry (IM-MS) may explain the co-occurrence of these two dissociation pathways. We reveal the direct relationship between the conformation of the calcineurin precursor ion and its concomitant dissociation pathway and provide insights into the mechanisms underlying this co-occurrence of the typical and atypical fragmentation mechanisms.
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Affiliation(s)
- Basak Kükrer
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Centre, Utrecht, The Netherlands
| | - Ioana M. Barbu
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Centre, Utrecht, The Netherlands
| | - Jeffrey Copps
- The Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Patrick Hogan
- La Jolla Institute for Allergy and Immunology, La Jolla, CA, USA
| | - Susan S. Taylor
- The Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Esther van Duijn
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Centre, Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- Netherlands Proteomics Centre, Utrecht, The Netherlands
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47
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Konermann L, Rodriguez AD, Liu J. On the formation of highly charged gaseous ions from unfolded proteins by electrospray ionization. Anal Chem 2012; 84:6798-804. [PMID: 22779749 DOI: 10.1021/ac301298g] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Electrospray ionization (ESI) of native proteins results in a narrow distribution of low protonation states. ESI for these folded species proceeds via the charged residue mechanism. In contrast, ESI of unfolded proteins yields a wide distribution of much higher charge states. The current work develops a model that can account for this effect. Recent molecular dynamics simulations revealed that ESI for unfolded polypeptide chains involves protein ejection from nanodroplets, representing a type of ion evaporation mechanism (IEM). We point out the analogies between this IEM, and the dissociation of gaseous protein complexes after collisional activation. The latter process commences with unraveling of a single subunit, in concert with Coulombically driven proton transfer. The subunit then separates from the residual complex as a highly charged ion. We propose that similar charge equilibration events accompany the IEM of unfolded proteins, thereby causing the formation of high ESI charge states. A bead chain model is used for examining how charge is partitioned as protein and droplet separate. It is shown that protein ejection from differently sized ESI droplets generates a range of protonation states. The predicted behavior agrees well with experimental data.
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Affiliation(s)
- Lars Konermann
- Department of Chemistry, Western University, London, Ontario, N6A 5B7 Canada.
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48
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Zhou M, Huang C, Wysocki VH. Surface-induced dissociation of ion mobility-separated noncovalent complexes in a quadrupole/time-of-flight mass spectrometer. Anal Chem 2012; 84:6016-23. [PMID: 22747517 DOI: 10.1021/ac300810u] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A custom in-line surface-induced dissociation (SID) device has been incorporated into a commercial ion mobility quadrupole/time-of-flight mass spectrometer in order to provide an alternative and potentially more informative activation method than the commonly used collision-induced dissociation (CID). Complicated sample mixtures can be fractionated by ion mobility (IM) and then dissociated by CID or SID for further structural analysis. Interpretation of SID spectra for cesium iodide clusters was greatly simplified with IM prior to dissociation because products originating from different precursors and overlapping in m/z but separated in drift time can be examined individually. Multiple conformations of two protein complexes, source-activated transthyretin tetramer and nativelike serum amyloid P decamer, were separated in ion mobility and subjected to CID and SID. CID spectra of the mobility separated conformations are similar. However, drastic differences can be observed for SID spectra of different conformations, implying different structures in the gas phase. This work highlights the potential of utilizing IM-SID to study quaternary structures of protein complexes and provides information that is complementary to our recently reported SID-IM approach.
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Affiliation(s)
- Mowei Zhou
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721-0041, United States
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49
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Zhou M, Dagan S, Wysocki VH. Protein Subunits Released by Surface Collisions of Noncovalent Complexes: Nativelike Compact Structures Revealed by Ion Mobility Mass Spectrometry. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108700] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Zhou M, Dagan S, Wysocki VH. Protein subunits released by surface collisions of noncovalent complexes: nativelike compact structures revealed by ion mobility mass spectrometry. Angew Chem Int Ed Engl 2012; 51:4336-9. [PMID: 22438323 DOI: 10.1002/anie.201108700] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/10/2012] [Indexed: 12/20/2022]
Affiliation(s)
- Mowei Zhou
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ, USA
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