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Webb IK. Perspective: The complex relationship between charge, mobility, and gas-phase protein structure. JOURNAL OF MASS SPECTROMETRY : JMS 2024; 59:e5013. [PMID: 38605450 DOI: 10.1002/jms.5013] [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: 01/18/2024] [Revised: 02/07/2024] [Accepted: 02/21/2024] [Indexed: 04/13/2024]
Abstract
Ion mobility spectrometry coupled to mass spectrometry (IMS/MS) is a widely used tool for biomolecular separations and structural elucidation. The application of IMS/MS has resulted in exciting developments in structural proteomics and genomics. This perspective gives a brief background of the field, addresses some of the important issues in making structural measurements, and introduces complementary techniques.
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Affiliation(s)
- Ian K Webb
- Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA
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2
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Fagerquist CK, Shi Y, Park J. Unusual modifications of protein biomarkers expressed by plasmid, prophage, and bacterial host of pathogenic Escherichia coli identified using top-down proteomic analysis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9667. [PMID: 38073204 DOI: 10.1002/rcm.9667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/04/2023] [Accepted: 10/05/2023] [Indexed: 12/18/2023]
Abstract
RATIONALE Pathogenic bacteria often carry prophage (bacterial viruses) and plasmids (small circular pieces of DNA) that may harbor toxin, antibacterial, and antibiotic resistance genes. Proteomic characterization of pathogenic bacteria should include the identification of host proteins and proteins produced by prophage and plasmid genomes. METHODS Protein biomarkers of two strains of Shiga toxin-producing Escherichia coli (STEC) were identified using antibiotic induction, matrix-assisted laser desorption/ionization tandem time-of-flight (MALDI-TOF-TOF) tandem mass spectrometry (MS/MS) with post-source decay (PSD), top-down proteomic (TDP) analysis, and plasmid sequencing. Alphafold2 was also used to compare predicted in silico structures of the identified proteins to prominent fragment ions generated using MS/MS-PSD. Strain samples were also analyzed with and without chemical reduction treatment to detect the attachment of pendant groups bound by thioester or disulfide bonds. RESULTS Shiga toxin was detected and/or identified in both STEC strains. For the first time, we also identified the osmotically inducible protein (OsmY) whose sequence unexpectedly had two forms: a full and a truncated sequence. The truncated OsmY terminates in the middle of an α-helix as determined by Alphafold2. A plasmid-encoded colicin immunity protein was also identified with and without attachment of an unidentified cysteine-bound pendant group (~307 Da). Plasmid sequencing confirmed top-down analysis and the identification of a promoter upstream of the immunity gene that is activated by antibiotic induction, that is, SOS box. CONCLUSIONS TDP analysis, coupled with other techniques (e.g., antibiotic induction, chemical reduction, plasmid sequencing, and in silico protein modeling), is a powerful tool to identify proteins (and their modifications), including prophage- and plasmid-encoded proteins, produced by pathogenic microorganisms.
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Affiliation(s)
- Clifton K Fagerquist
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, California, USA
| | - Yanlin Shi
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, California, USA
| | - Jihyun Park
- Produce Safety and Microbiology Research Unit, Western Regional Research Center, Agricultural Research Service, US Department of Agriculture, Albany, California, USA
- Oak Ridge Institute for Science and Education, US Department of Energy, Oak Ridge, Tennessee, USA
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3
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Cain RL, Webb IK. Online protein unfolding characterized by ion mobility electron capture dissociation mass spectrometry: cytochrome C from neutral and acidic solutions. Anal Bioanal Chem 2023; 415:749-758. [PMID: 36622393 DOI: 10.1007/s00216-022-04501-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/02/2022] [Accepted: 12/20/2022] [Indexed: 01/10/2023]
Abstract
Electrospray ionization mass spectrometry (ESI-MS) experiments, including ion mobility spectrometry mass spectrometry (ESI-IMS-MS) and electron capture dissociation (ECD) of proteins ionized from aqueous solutions, have been used for the study of solution-like structures of intact proteins. By mixing aqueous proteins with denaturants online before ESI, the amount of protein unfolding can be precisely controlled and rapidly analyzed, permitting the characterization of protein folding intermediates in protein folding pathways. Herein, we mixed various pH solutions online with aqueous cytochrome C for unfolding and characterizing its unfolding intermediates with ESI-MS charge state distribution measurements, IMS, and ECD. The presence of folding intermediates and unfolded cytochrome c structures were detected from changes in charge states, arrival time distributions (ATDs), and ECD. We also compared structures from nondenaturing and denaturing solution mixtures measured under "gentle" (i.e., low energy) ion transmission conditions with structures measured under "harsh" (i.e., higher energy) transmission. This work confirms that when using "gentle" instrument conditions, the gas-phase cytochrome c ions reflect attributes of the various solution-phase structures. However, "harsh" conditions that maximize ion transmission produce extended structures that no longer correlate with changes in solution structure.
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Affiliation(s)
- Rebecca L Cain
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Ian K Webb
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 46202, USA.
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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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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Scaffolding mechanism of arrestin-2 in the cRaf/MEK1/ERK signaling cascade. Proc Natl Acad Sci U S A 2021; 118:2026491118. [PMID: 34507982 DOI: 10.1073/pnas.2026491118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2021] [Indexed: 01/14/2023] Open
Abstract
Arrestins were initially identified for their role in homologous desensitization and internalization of G protein-coupled receptors. Receptor-bound arrestins also initiate signaling by interacting with other signaling proteins. Arrestins scaffold MAPK signaling cascades, MAPK kinase kinase (MAP3K), MAPK kinase (MAP2K), and MAPK. In particular, arrestins facilitate ERK1/2 activation by scaffolding ERK1/2 (MAPK), MEK1 (MAP2K), and Raf (MAPK3). However, the structural mechanism underlying this scaffolding remains unknown. Here, we investigated the mechanism of arrestin-2 scaffolding of cRaf, MEK1, and ERK2 using hydrogen/deuterium exchange-mass spectrometry, tryptophan-induced bimane fluorescence quenching, and NMR. We found that basal and active arrestin-2 interacted with cRaf, while only active arrestin-2 interacted with MEK1 and ERK2. The ATP binding status of MEK1 or ERK2 affected arrestin-2 binding; ATP-bound MEK1 interacted with arrestin-2, whereas only empty ERK2 bound arrestin-2. Analysis of the binding interfaces suggested that the relative positions of cRaf, MEK1, and ERK2 on arrestin-2 likely facilitate sequential phosphorylation in the signal transduction cascade.
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6
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Wu F, Wang Y, Chen Y, Li Z, Ding CF. Alkali metal ion-induced conformation changes of methionine- and leucine enkephalin investigated by gas-phase hydrogen/deuterium exchange combined with theoretical calculations. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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7
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Zhou M, Lantz C, Brown KA, Ge Y, Paša-Tolić L, Loo JA, Lermyte F. Higher-order structural characterisation of native proteins and complexes by top-down mass spectrometry. Chem Sci 2020; 11:12918-12936. [PMID: 34094482 PMCID: PMC8163214 DOI: 10.1039/d0sc04392c] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/05/2020] [Indexed: 12/11/2022] Open
Abstract
In biology, it can be argued that if the genome contains the script for a cell's life cycle, then the proteome constitutes an ensemble cast of actors that brings these instructions to life. Their interactions with each other, co-factors, ligands, substrates, and so on, are key to understanding nearly any biological process. Mass spectrometry is well established as the method of choice to determine protein primary structure and location of post-translational modifications. In recent years, top-down fragmentation of intact proteins has been increasingly combined with ionisation of noncovalent assemblies under non-denaturing conditions, i.e., native mass spectrometry. Sequence, post-translational modifications, ligand/metal binding, protein folding, and complex stoichiometry can thus all be probed directly. Here, we review recent developments in this new and exciting field of research. While this work is written primarily from a mass spectrometry perspective, it is targeted to all bioanalytical scientists who are interested in applying these methods to their own biochemistry and chemical biology research.
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Affiliation(s)
- Mowei Zhou
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory Richland WA 99354 USA
| | - Carter Lantz
- Department of Chemistry and Biochemistry, Department of Biological Chemistry, University of California-Los Angeles Los Angeles CA 90095 USA
| | - Kyle A Brown
- Department of Chemistry, University of Wisconsin-Madison Madison WI 53706 USA
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison Madison WI 53706 USA
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison Madison WI 53706 USA
| | - Ljiljana Paša-Tolić
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory Richland WA 99354 USA
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, Department of Biological Chemistry, University of California-Los Angeles Los Angeles CA 90095 USA
| | - Frederik Lermyte
- Department of Chemistry, Institute of Chemistry and Biochemistry, Technical University of Darmstadt 64287 Darmstadt Germany
- Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège 4000 Liège Belgium
- School of Engineering, University of Warwick Coventry CV4 7AL UK
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8
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Simmonds AL, Lopez-Clavijo AF, Winn PJ, Russell DH, Styles IB, Cooper HJ. Structural Analysis of 14-3-3-ζ-Derived Phosphopeptides Using Electron Capture Dissociation Mass Spectrometry, Traveling Wave Ion Mobility Spectrometry, and Molecular Modeling. J Phys Chem B 2020; 124:461-469. [PMID: 31859508 DOI: 10.1021/acs.jpcb.9b08506] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Previously, we have demonstrated the effect of salt bridges on the electron capture dissociation mass spectrometry behavior of synthetic model phosphopeptides and applied an ion mobility spectrometry/molecular modeling approach to rationalize the findings in terms of peptide ion structure. Here, we develop and apply the approach to a biologically derived phosphopeptide. Specifically, we have investigated variants of a 15-mer phosphopeptide VVGARRSsWRVVSSI (s denotes phosphorylated Ser) derived from Akt1 substrate 14-3-3-ζ, which contains the phosphorylation motif RRSsWR. Variants were generated by successive arginine-to-leucine substitutions within the phosphorylation motif. ECD fragmentation patterns for the eight phosphopeptide variants show greater sequence coverage with successive R → L substitutions. Peptides with two or more basic residues had regions with no sequence coverage, while full sequence coverage was observed for peptides with one or no basic residues. For three of the peptide variants, low-abundance fragments were observed between the phosphoserine and a basic residue, possibly due to the presence of multiple conformers with and without noncovalent interactions between these residues. For the five variants whose dissociation behavior suggested the presence of intramolecular noncovalent interactions, we employed ion mobility spectrometry and molecular modeling to probe the nature of these interactions. Our workflow allowed us to propose candidate structures whose noncovalent interactions were consistent with the ECD data for all of the peptides modeled. Additionally, the AMBER parameter sets created for and validated by this work are presented and made available online ( http://www.biosciences-labs.bham.ac.uk/cooper/datasets.php ).
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Affiliation(s)
| | | | | | - David H Russell
- Texas A&M University , College Station , Texas 77843 , United States
| | - Iain B Styles
- Centre of Membrane Proteins and Receptors (COMPARE) , Universities of Birmingham and Nottingham , Midlands , U.K
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9
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Vuong VQ, Nishimoto Y, Fedorov DG, Sumpter BG, Niehaus TA, Irle S. The Fragment Molecular Orbital Method Based on Long-Range Corrected Density-Functional Tight-Binding. J Chem Theory Comput 2019; 15:3008-3020. [PMID: 30998360 DOI: 10.1021/acs.jctc.9b00108] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The presently available linear scaling approaches to density-functional tight-binding (DFTB) based on the fragment molecular orbital (FMO) method are severely impacted by the problem of artificial charge transfer due to the self-interaction error (SIE), which hampers the simulation of zwitterionic systems such as biopolymers or ionic liquids. Here we report an extension of FMO-DFTB where we included a long-range corrected (LC) functional designed to mitigate the DFTB SIE, called the FMO-LC-DFTB method, resulting in a robust method which succeeds in simulating zwitterionic systems. Both energy and analytic gradient are developed for the gas phase and the polarizable continuum model of solvation. The scaling of FMO-LC-DFTB with system size N is shown to be almost linear, O( N1.13-1.28), and its numerical accuracy is established for a variety of representative systems including neutral and charged polypeptides. It is shown that pair interaction energies between fragments for two mini-proteins are in excellent agreement with results from long-range corrected density functional theory. The new method was employed in long time scale (1 ns) molecular dynamics simulations of the tryptophan cage protein (PDB: 1L2Y ) in the gas phase for four different protonation states and in stochastic global minimum structure searches for 1-ethyl-3-methylimidazolium nitrate ionic liquid clusters containing up to 2300 atoms.
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Affiliation(s)
- Van Quan Vuong
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Yoshio Nishimoto
- Fukui Institute for Fundamental Chemistry , Kyoto University , Kyoto 606-8501 , Japan
| | - Dmitri G Fedorov
- Research Center for Computational Design of Advanced Functional Materials (CD-FMat) , National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8568 , Japan
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences and Computational Sciences and Engineering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Thomas A Niehaus
- Univ Lyon, Université Claude Bernard Lyon 1 , CNRS, Institut Lumière Matière , F-69622 Villeurbanne , France
| | - Stephan Irle
- Bredesen Center for Interdisciplinary Research and Graduate Education , University of Tennessee , Knoxville , Tennessee 37996 , United States.,Center for Nanophase Materials Sciences and Computational Sciences and Engineering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States.,Chemical Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
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10
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Pitts-McCoy AM, Harrilal CP, McLuckey SA. Gas-Phase Ion/Ion Chemistry as a Probe for the Presence of Carboxylate Groups in Polypeptide Cations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:329-338. [PMID: 30341581 PMCID: PMC6347497 DOI: 10.1007/s13361-018-2079-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/04/2018] [Indexed: 05/31/2023]
Abstract
The reactivity of 1-hydroxybenzoyl triazole (HOBt) esters with the carboxylate functionality present in peptides is demonstrated in the gas phase with a doubly deprotonated dianion. The reaction forms an anhydride linkage at the carboxylate site. Upon ion trap collisional-induced dissociation (CID) of the modified peptide, the resulting spectrum shows a nominal loss of the mass of the reagent and a water molecule. Analogous phenomenology was also noted for model peptide cations that likely contain zwitterionic/salt-bridged motifs in reactions with a negatively charged HOBt ester. Control experiments indicate that a carboxylate group is the likely reactive site, rather than other possible nucleophilic sites present in the peptide. These observations suggest that HOBt ester chemistry may be used as a chemical probe for the presence and location of carboxylate groups in net positively charged polypeptide ions. As an illustration, deprotonated sulfobenzoyl HOBt was reacted with the [M+7H]7+ ion of ubiquitin. The ion was shown to react with the reagent and CID of the covalent reaction product yielded an abundant [M+6H-H2O]6+ ion. Comparison of the CID product ion spectrum of this ion with that of the water loss product generated from CID of the unmodified [M+6H]6+ ion revealed the glutamic acid at residue 64 as a reactive site, suggesting that it is present in the deprotonated form. Graphical Abstract ᅟ.
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Affiliation(s)
- Anthony M Pitts-McCoy
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Christopher P Harrilal
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA.
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11
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Lermyte F, Valkenborg D, Loo JA, Sobott F. Radical solutions: Principles and application of electron-based dissociation in mass spectrometry-based analysis of protein structure. MASS SPECTROMETRY REVIEWS 2018; 37:750-771. [PMID: 29425406 PMCID: PMC6131092 DOI: 10.1002/mas.21560] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 05/11/2023]
Abstract
In recent years, electron capture (ECD) and electron transfer dissociation (ETD) have emerged as two of the most useful methods in mass spectrometry-based protein analysis, evidenced by a considerable and growing body of literature. In large part, the interest in these methods is due to their ability to induce backbone fragmentation with very little disruption of noncovalent interactions which allows inference of information regarding higher order structure from the observed fragmentation behavior. Here, we review the evolution of electron-based dissociation methods, and pay particular attention to their application in "native" mass spectrometry, their mechanism, determinants of fragmentation behavior, and recent developments in available instrumentation. Although we focus on the two most widely used methods-ECD and ETD-we also discuss the use of other ion/electron, ion/ion, and ion/neutral fragmentation methods, useful for interrogation of a range of classes of biomolecules in positive- and negative-ion mode, and speculate about how this exciting field might evolve in the coming years.
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Affiliation(s)
- Frederik Lermyte
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerp, Belgium
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- School of Engineering, University of Warwick, Coventry, United Kingdom
| | - Dirk Valkenborg
- Centre for Proteomics, University of Antwerp, Antwerp, Belgium
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Agoralaan, Diepenbeek, Belgium
- Applied Bio and Molecular Systems, Flemish Institute for Technological Research (VITO), Mol, Belgium
| | - Joseph A Loo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California
- UCLA/DOE Institute for Genomics and Proteomics, University of California-Los Angeles, Los Angeles, California
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California
| | - Frank Sobott
- Biomolecular and Analytical Mass Spectrometry Group, Department of Chemistry, University of Antwerp, Antwerp, Belgium
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
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12
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Affiliation(s)
- Nicholas
M. Riley
- Department
of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Genome
Center of Wisconsin, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Joshua J. Coon
- Department
of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Genome
Center of Wisconsin, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Department
of Biomolecular Chemistry, University of
Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Morgridge
Institute for Research, Madison, Wisconsin 53715, United States
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13
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Heiles S, Berden G, Oomens J, Williams ER. Competition between salt bridge and non-zwitterionic structures in deprotonated amino acid dimers. Phys Chem Chem Phys 2018; 20:15641-15652. [DOI: 10.1039/c8cp01458b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The effect of side chain functional groups on salt bridge structures in deprotonated amino acid homodimers is investigated using both infrared multiple photon dissociation spectroscopy between 650 and 1850 cm−1 and theory.
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Affiliation(s)
- Sven Heiles
- Department of Chemistry
- University of California
- Berkeley
- USA
- Institute of Inorganic and Analytical Chemistry
| | - Giel Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Jos Oomens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
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14
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Jhingree JR, Bellina B, Pacholarz KJ, Barran PE. Charge Mediated Compaction and Rearrangement of Gas-Phase Proteins: A Case Study Considering Two Proteins at Opposing Ends of the Structure-Disorder Continuum. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1450-1461. [PMID: 28585116 PMCID: PMC5486678 DOI: 10.1007/s13361-017-1692-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/10/2017] [Accepted: 04/11/2017] [Indexed: 05/22/2023]
Abstract
Charge reduction in the gas phase provides a direct means of manipulating protein charge state, and when coupled to ion mobility mass spectrometry (IM-MS), it is possible to monitor the effect of charge on protein conformation in the absence of solution. Use of the electron transfer reagent 1,3-dicyanobenzene, coupled with IM-MS, allows us to monitor the effect of charge reduction on the conformation of two proteins deliberately chosen from opposite sides of the order to disorder continuum: bovine pancreatic trypsin inhibitor (BPTI) and beta casein. The ordered BPTI presents compact conformers for each of three charge states accompanied by narrow collision cross-section distributions (TWCCSDN2→He). Upon reduction of BPTI, irrespective of precursor charge state, the TWCCSN2→He decreases to a similar distribution as found for the nESI generated ion of identical charge. The behavior of beta casein upon charge reduction is more complex. It presents over a wide charge state range (9-28), and intermediate charge states (13-18) have broad TWCCSDN2→He with multiple conformations, where both compaction and rearrangement are seen. Further, we see that the TWCCSDN2→He of the latter charge states are even affected by the presence of radical anions. Overall, we conclude that the flexible nature of some proteins result in broad conformational distributions comprised of many families, even for single charge states, and the barrier between different states can be easily overcome by an alteration of the net charge. Graphical Abstract ᅟ.
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Affiliation(s)
- Jacquelyn R Jhingree
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Bruno Bellina
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Kamila J Pacholarz
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Perdita E Barran
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
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