1
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Hanifi K, Scrosati PM, Konermann L. MD Simulations of Peptide-Containing Electrospray Droplets: Effects of Parameter Settings on the Predicted Mechanisms of Gas Phase Ion Formation. J Phys Chem B 2024; 128:5973-5986. [PMID: 38864851 DOI: 10.1021/acs.jpcb.4c01241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
Electrospray ionization (ESI) mass spectrometry is widely used for interrogating peptides, proteins, and other biomolecular analytes. A growing number of laboratories use molecular dynamics (MD) simulations for uncovering ESI mechanisms by modeling the behavior of highly charged nanodroplets. The outcome of any MD simulation depends on certain assumptions and parameter settings, and it is desirable to optimize these factors by benchmarking computational data against experiments. Unfortunately, benchmarking of ESI simulations is difficult because experimentally generated gaseous ions do not generally retain any features that would reveal their formation pathway [e.g., the charged residue mechanism (CRM) or the ion evaporation mechanism (IEM)]. Here, we tackle this problem by examining the effects of various MD settings on the ESI behavior of the 9-residue peptide bradykinin in acidic aqueous droplets. Several parameters were found to significantly affect the kinetic competition between peptide IEM and CRM. By systematically probing the droplet behavior, we uncovered problems associated with certain settings, including peptide/solvent temperature imbalances, unexpected peptide deceleration during IEM, and a dependence of the ESI mechanism on the water model. We also noted different simulation outcomes for different force fields. On the basis of comprehensive tests, we propose a set of "best practice" parameter settings for MD simulations of ESI droplets. The strategies used here should be transferable to other types of droplet simulations, paving the way toward a more solid understanding of ESI mechanisms.
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Affiliation(s)
- Kasra Hanifi
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Pablo M Scrosati
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
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2
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Stincone P, Naimi A, Saviola AJ, Reher R, Petras D. Decoding the molecular interplay in the central dogma: An overview of mass spectrometry-based methods to investigate protein-metabolite interactions. Proteomics 2024; 24:e2200533. [PMID: 37929699 DOI: 10.1002/pmic.202200533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/15/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023]
Abstract
With the emergence of next-generation nucleotide sequencing and mass spectrometry-based proteomics and metabolomics tools, we have comprehensive and scalable methods to analyze the genes, transcripts, proteins, and metabolites of a multitude of biological systems. Despite the fascinating new molecular insights at the genome, transcriptome, proteome and metabolome scale, we are still far from fully understanding cellular organization, cell cycles and biology at the molecular level. Significant advances in sensitivity and depth for both sequencing as well as mass spectrometry-based methods allow the analysis at the single cell and single molecule level. At the same time, new tools are emerging that enable the investigation of molecular interactions throughout the central dogma of molecular biology. In this review, we provide an overview of established and recently developed mass spectrometry-based tools to probe metabolite-protein interactions-from individual interaction pairs to interactions at the proteome-metabolome scale.
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Affiliation(s)
- Paolo Stincone
- University of Tuebingen, CMFI Cluster of Excellence, Interfaculty Institute of Microbiology and Infection Medicine, Tuebingen, Germany
- University of Tuebingen, Center for Plant Molecular Biology, Tuebingen, Germany
| | - Amira Naimi
- University of Marburg, Institute of Pharmaceutical Biology and Biotechnology, Marburg, Germany
| | | | - Raphael Reher
- University of Marburg, Institute of Pharmaceutical Biology and Biotechnology, Marburg, Germany
| | - Daniel Petras
- University of Tuebingen, CMFI Cluster of Excellence, Interfaculty Institute of Microbiology and Infection Medicine, Tuebingen, Germany
- University of California Riverside, Department of Biochemistry, Riverside, USA
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3
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Kang WY, Mondal A, Bonney JR, Perez A, Prentice BM. Structural Elucidation of Ubiquitin via Gas-Phase Ion/Ion Cross-Linking Reactions Using Sodium-Cationized Reagents Coupled with Infrared Multiphoton Dissociation. Anal Chem 2024; 96:8518-8527. [PMID: 38711366 PMCID: PMC11161031 DOI: 10.1021/acs.analchem.4c00442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Accurate structural determination of proteins is critical to understanding their biological functions and the impact of structural disruption on disease progression. Gas-phase cross-linking mass spectrometry (XL-MS) via ion/ion reactions between multiply charged protein cations and singly charged cross-linker anions has previously been developed to obtain low-resolution structural information on proteins. This method significantly shortens experimental time relative to conventional solution-phase XL-MS but has several technical limitations: (1) the singly deprotonated N-hydroxysulfosuccinimide (sulfo-NHS)-based cross-linker anions are restricted to attachment at neutral amine groups of basic amino acid residues and (2) analyzing terminal cross-linked fragment ions is insufficient to unambiguously localize sites of linker attachment. Herein, we demonstrate enhanced structural information for alcohol-denatured A-state ubiquitin obtained from an alternative gas-phase XL-MS approach. Briefly, singly sodiated ethylene glycol bis(sulfosuccinimidyl succinate) (sulfo-EGS) cross-linker anions enable covalent cross-linking at both ammonium and amine groups. Additionally, covalently modified internal fragment ions, along with terminal b-/y-type counterparts, improve the determination of linker attachment sites. Molecular dynamics simulations validate experimentally obtained gas-phase conformations of denatured ubiquitin. This method has identified four cross-linking sites across 8+ ubiquitin, including two new sites in the N-terminal region of the protein that were originally inaccessible in prior gas-phase XL approaches. The two N-terminal cross-linking sites suggest that the N-terminal half of ubiquitin is more compact in gas-phase conformations. By comparison, the two C-terminal linker sites indicate the signature transformation of this region of the protein from a native to a denatured conformation. Overall, the results suggest that the solution-phase secondary structures of the A-state ubiquitin are conserved in the gas phase. This method also provides sufficient sensitivity to differentiate between two gas-phase conformers of the same charge state with subtle structural variations.
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Affiliation(s)
| | - Arup Mondal
- Department of Chemistry, University of Florida
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4
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Zimnicka MM. Structural studies of supramolecular complexes and assemblies by ion mobility mass spectrometry. MASS SPECTROMETRY REVIEWS 2024; 43:526-559. [PMID: 37260128 DOI: 10.1002/mas.21851] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 04/26/2023] [Accepted: 05/10/2023] [Indexed: 06/02/2023]
Abstract
Recent advances in instrumentation and development of computational strategies for ion mobility mass spectrometry (IM-MS) studies have contributed to an extensive growth in the application of this analytical technique to comprehensive structural description of supramolecular systems. Apart from the benefits of IM-MS for interrogation of intrinsic properties of noncovalent aggregates in the experimental gas-phase environment, its merits for the description of native structural aspects, under the premises of having maintained the noncovalent interactions innate upon the ionization process, have attracted even more attention and gained increasing interest in the scientific community. Thus, various types of supramolecular complexes and assemblies relevant for biological, medical, material, and environmental sciences have been characterized so far by IM-MS supported by computational chemistry. This review covers the state-of-the-art in this field and discusses experimental methods and accompanying computational approaches for assessing the reliable three-dimensional structural elucidation of supramolecular complexes and assemblies by IM-MS.
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Affiliation(s)
- Magdalena M Zimnicka
- Mass Spectrometry Group, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland
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5
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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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6
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Wesdemiotis C, Williams-Pavlantos KN, Keating AR, McGee AS, Bochenek C. Mass spectrometry of polymers: A tutorial review. MASS SPECTROMETRY REVIEWS 2024; 43:427-476. [PMID: 37070280 DOI: 10.1002/mas.21844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 03/03/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Ever since the inception of synthetic polymeric materials in the late 19th century, the number of studies on polymers as well as the complexity of their structures have only increased. The development and commercialization of new polymers with properties fine-tuned for specific technological, environmental, consumer, or biomedical applications requires powerful analytical techniques that permit the in-depth characterization of these materials. One such method with the ability to provide chemical composition and structure information with high sensitivity, selectivity, specificity, and speed is mass spectrometry (MS). This tutorial review presents and exemplifies the various MS techniques available for the elucidation of specific structural features in a synthetic polymer, including compositional complexity, primary structure, architecture, topology, and surface properties. Key to every MS analysis is sample conversion to gas-phase ions. This review describes the fundamentals of the most suitable ionization methods for synthetic materials and provides relevant sample preparation protocols. Most importantly, structural characterizations via one-step as well as hyphenated or multidimensional approaches are introduced and demonstrated with specific applications, including surface sensitive and imaging techniques. The aim of this tutorial review is to illustrate the capabilities of MS for the characterization of large, complex polymers and emphasize its potential as a powerful compositional and structural elucidation tool in polymer chemistry.
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Affiliation(s)
| | | | - Addie R Keating
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Andrew S McGee
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Calum Bochenek
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
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7
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Brodmerkel MN, Thiede L, De Santis E, Uetrecht C, Caleman C, Marklund EG. Collision induced unfolding and molecular dynamics simulations of norovirus capsid dimers reveal strain-specific stability profiles. Phys Chem Chem Phys 2024; 26:13094-13105. [PMID: 38628116 DOI: 10.1039/d3cp06344e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Collision induced unfolding (CIU) is a method used with ion mobility mass spectrometry to examine protein structures and their stability. Such experiments yield information about higher order protein structures, yet are unable to provide details about the underlying processes. That information can however be provided using molecular dynamics simulations. Here, we investigate the gas-phase unfolding of norovirus capsid dimers from the Norwalk and Kawasaki strains by employing molecular dynamics simulations over a range of temperatures, representing different levels of activation, together with CIU experiments. The dimers have highly similar structures, but their CIU reveals different stability that can be explained by the different dynamics that arises in response to the activation seen in the simulations, including a part of the sequence with previously observed strain-specific dynamics in solution. Our findings show how similar protein variants can be examined using mass spectrometric techniques in conjunction with atomistic molecular dynamics simulations to reveal differences in stability as well as differences in how and where unfolding takes place upon activation.
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Affiliation(s)
- Maxim N Brodmerkel
- Department of Chemistry - BMC, Uppsala University, 75123 Uppsala, Sweden.
| | - Lars Thiede
- CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY, Leibniz Institute of Virology (LIV), Notkestrasse 85, 22607 Hamburg, Germany
- Institute of Chemistry and Metabolomics, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Emiliano De Santis
- Department of Chemistry - BMC, Uppsala University, 75123 Uppsala, Sweden.
- Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
| | - Charlotte Uetrecht
- CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY, Leibniz Institute of Virology (LIV), Notkestrasse 85, 22607 Hamburg, Germany
- Institute of Chemistry and Metabolomics, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Carl Caleman
- Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
- Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Erik G Marklund
- Department of Chemistry - BMC, Uppsala University, 75123 Uppsala, Sweden.
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8
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Shepherd SO, Green AW, Resendiz ES, Newton KR, Kurulugama RT, Prell JS. Effects of Nano-Electrospray Ionization Emitter Position on Unintentional In-Source Activation of Peptide and Protein Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:498-507. [PMID: 38374644 DOI: 10.1021/jasms.3c00371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Native ion mobility-mass spectrometry (IM-MS) typically introduces protein ions into the gas phase through nano-electrospray ionization (nESI). Many nESI setups have mobile stages for tuning the ion signal and extent of co-solute and salt adduction. However, tuning the position of the emitter capillary in nESI can have unintended downstream consequences for collision-induced unfolding or collision-induced dissociation (CIU/D) experiments. Here, we show that relatively small variations in the nESI emitter position can shift the midpoint (commonly called the "CID50" or "CIU50") potential of CID breakdown curves and CIU transitions by as much as 8 V on commercial instruments. A spatial "map" of the shift in CID50 for the loss of heme from holomyoglobin onto the emitter position on a Waters Synapt G2-Si mass spectrometer shows that emitter positions closer to the instrument inlet can result in significantly greater in-source activation, whereas different effects are found on an Agilent 6545XT instrument for the ions studied. A similar effect is observed for CID of the singly protonated leucine enkephalin peptide and Shiga toxin 1 subunit B homopentamer on the Waters Synapt G2-Si instrument. In-source activation effects on a Waters Synapt G2-Si are also investigated by examining the RMSD between CIU fingerprints acquired at different emitter positions and the shifts in CIU50 for structural transitions of bovine serum albumin and NIST monoclonal antibody.
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Affiliation(s)
- Samantha O Shepherd
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Austin W Green
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Elizabeth S Resendiz
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Kenneth R Newton
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
- Agilent Technologies, 5301 Stevens Creek Blvd, Santa Clara, California 95051, United States
| | - Ruwan T Kurulugama
- Agilent Technologies, 5301 Stevens Creek Blvd, Santa Clara, California 95051, United States
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
- Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1252, United States
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9
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Anders AG, Tidwell ED, Gadkari VV, Koutmos M, Ruotolo BT. Collision-Induced Unfolding Reveals Disease-Associated Stability Shifts in Mitochondrial Transfer Ribonucleic Acids. J Am Chem Soc 2024; 146:4412-4420. [PMID: 38329282 DOI: 10.1021/jacs.3c09230] [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: 02/09/2024]
Abstract
Ribonucleic acids (RNAs) remain challenging targets for structural biology, creating barriers to understanding their vast functions in cellular biology and fully realizing their applications in biotechnology. The inherent dynamism of RNAs creates numerous obstacles in capturing their biologically relevant higher-order structures (HOSs), and as a result, many RNA functions remain unknown. In this study, we describe the development of native ion mobility-mass spectrometry and collision-induced unfolding (CIU) for the structural characterization of a variety of RNAs. We evaluate the ability of these techniques to preserve native structural features in the gas phase across a wide range of functional RNAs. Finally, we apply these tools to study the elusive mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes-associated A3243G mutation. Our data demonstrate that our experimentally determined conditions preserve some solution-state memory of RNAs via the correlated complexity of CIU fingerprints and RNA HOS, the observation of predicted stability shifts in the control RNA samples, and the retention of predicted magnesium binding events in gas-phase RNA ions. Significant differences in collision cross section and stability are observed as a function of the A3243G mutation across a subset of the mitochondrial tRNA maturation pathway. We conclude by discussing the potential application of CIU for the development of RNA-based biotherapeutics and, more broadly, transcriptomic characterization.
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Affiliation(s)
- Anna G Anders
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Elizabeth D Tidwell
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Varun V Gadkari
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Markos Koutmos
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Brandon T Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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10
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Esser TK, Böhning J, Önür A, Chinthapalli DK, Eriksson L, Grabarics M, Fremdling P, Konijnenberg A, Makarov A, Botman A, Peter C, Benesch JLP, Robinson CV, Gault J, Baker L, Bharat TAM, Rauschenbach S. Cryo-EM of soft-landed β-galactosidase: Gas-phase and native structures are remarkably similar. SCIENCE ADVANCES 2024; 10:eadl4628. [PMID: 38354247 PMCID: PMC10866560 DOI: 10.1126/sciadv.adl4628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/11/2024] [Indexed: 02/16/2024]
Abstract
Native mass spectrometry (MS) has become widely accepted in structural biology, providing information on stoichiometry, interactions, homogeneity, and shape of protein complexes. Yet, the fundamental assumption that proteins inside the mass spectrometer retain a structure faithful to native proteins in solution remains a matter of intense debate. Here, we reveal the gas-phase structure of β-galactosidase using single-particle cryo-electron microscopy (cryo-EM) down to 2.6-Å resolution, enabled by soft landing of mass-selected protein complexes onto cold transmission electron microscopy (TEM) grids followed by in situ ice coating. We find that large parts of the secondary and tertiary structure are retained from the solution. Dehydration-driven subunit reorientation leads to consistent compaction in the gas phase. By providing a direct link between high-resolution imaging and the capability to handle and select protein complexes that behave problematically in conventional sample preparation, the approach has the potential to expand the scope of both native mass spectrometry and cryo-EM.
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Affiliation(s)
- Tim K. Esser
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
- Thermo Fisher Scientific, 1 Boundary Park, Hemel Hempstead, Hertfordshire HP2 7GE, UK
| | - Jan Böhning
- Structural Studies Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Alpcan Önür
- Department of Chemistry, University of Konstanz, Konstanz 78457, Germany
| | - Dinesh K. Chinthapalli
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
| | - Lukas Eriksson
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
| | - Marko Grabarics
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
| | - Paul Fremdling
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | | | - Alexander Makarov
- Thermo Fisher Scientific, Bremen 28199, Germany
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Centre for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, Netherlands
| | - Aurelien Botman
- Thermo Fisher Scientific, 5350 NE Dawson Creek Drive, Hillsboro, OR 97124, USA
| | - Christine Peter
- Department of Chemistry, University of Konstanz, Konstanz 78457, Germany
| | - Justin L. P. Benesch
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
| | - Carol V. Robinson
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
| | - Joseph Gault
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Lindsay Baker
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Tanmay A. M. Bharat
- Structural Studies Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Stephan Rauschenbach
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Kavli Institute for NanoScience Discovery, Dorothy Crowfoot Hodgkin Building, Oxford OX1 3QU, UK
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11
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Cheung See Kit M, Cropley TC, Bleiholder C, Chouinard CD, Sobott F, Webb IK. The role of solvation on the conformational landscape of α-synuclein. Analyst 2023; 149:125-136. [PMID: 37982746 PMCID: PMC10760066 DOI: 10.1039/d3an01680c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
Native ion mobility mass spectrometry has been used extensively to characterize ensembles of intrinsically disordered protein (IDP) conformers, but the extent to which the gaseous measurements provide realistic pictures of the solution conformations for such flexible proteins remains unclear. Therefore, we systematically studied the relationship between the solution and gaseous structural ensembles by measuring electrospray charge state and collision cross section (CCS) distributions for cationic and anionic forms of α-synuclein (αSN), an anionic protein in solution, as well as directly probed gas phase residue to residue distances via ion/ion reactions between gaseous α-synuclein cations and disulfonic acid linkers that form strong electrostatic bonds. We also combined results from in-solution protein crosslinking identified from native tandem mass spectrometry (MS/MS) with an initial αSN ensemble generated computationally by IDPConformerGenerator to generate an experimentally restrained solution ensemble of αSN. CCS distributions were directly calculated for the solution ensembles determined by NMR and compared to predicted gaseous conformers. While charge state and collision cross section distributions are useful for qualitatively describing the relative structural dynamics of proteins and major conformational changes induced by changes to solution states, the predicted and measured gas phase conformers include subpopulations that are significantly different than those expected from completely "freezing" solution conformations and preserving them in the gas phase. However, insights were gained on the various roles of solvent in stabilizing various conformers for extremely dynamic proteins like α-synuclein.
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Affiliation(s)
- Melanie Cheung See Kit
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
| | - Tyler C Cropley
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA
| | - Christian Bleiholder
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA
| | | | - Frank Sobott
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ian K Webb
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, USA.
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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12
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Edwards AN, Blue AJ, Conforti JM, Cordes MS, Trakselis MA, Gallagher ES. Gas-phase stability and thermodynamics of ligand-bound, binary complexes of chloramphenicol acetyltransferase reveal negative cooperativity. Anal Bioanal Chem 2023; 415:6201-6212. [PMID: 37542535 DOI: 10.1007/s00216-023-04891-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/17/2023] [Accepted: 07/24/2023] [Indexed: 08/07/2023]
Abstract
The biological role of the bacterial chloramphenicol (Chl)-resistance enzyme, chloramphenicol acetyltransferase (CAT), has seen renewed interest due to the resurgent use of Chl against multi-drug-resistant microbes. This looming threat calls for more rationally designed antibiotic derivatives that have improved antimicrobial properties and reduced toxicity in humans. Herein, we utilize native ion mobility spectrometry-mass spectrometry (IMS-MS) to investigate the gas-phase structure and thermodynamic stability of the type I variant of CAT from Escherichia coli (EcCATI) and several EcCATI:ligand-bound complexes. EcCATI readily binds multiple Chl without incurring significant changes to its gas-phase structure or stability. A non-hydrolyzable acetyl-CoA derivative (S-ethyl-CoA, S-Et-CoA) was used to kinetically trap EcCATI and Chl in a ternary, ligand-bound state (EcCATI:S-Et-CoA:Chl). Using collision-induced unfolding (CIU)-IMS-MS, we find that Chl dissociates from EcCATI:S-Et-CoA:Chl complexes at low collision energies, while S-Et-CoA remains bound to EcCATI even as protein unfolding occurs. Gas-phase binding constants further suggest that EcCATI binds S-Et-CoA more tightly than Chl. Both ligands exhibit negative cooperativity of subsequent ligand binding in their respective binary complexes. While we observe no significant change in structure or stability to EcCATI when bound to either or both ligands, we have elucidated novel gas-phase unfolding and dissociation behavior and provided a foundation for further characterization of alternative substrates and/or inhibitors of EcCATI.
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Affiliation(s)
- Alexis N Edwards
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
| | - Anthony J Blue
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
| | - Jessica M Conforti
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
| | - Michael S Cordes
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
| | - Elyssia S Gallagher
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA.
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13
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Rolland AD, Takata T, Donor MT, Lampi KJ, Prell JS. Eye lens β-crystallins are predicted by native ion mobility-mass spectrometry and computations to form compact higher-ordered heterooligomers. Structure 2023; 31:1052-1064.e3. [PMID: 37453416 PMCID: PMC10528727 DOI: 10.1016/j.str.2023.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 05/04/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023]
Abstract
Eye lens α- and β-/γ-crystallin proteins are not replaced after fiber cell denucleation and maintain lens transparency and refractive properties. The exceptionally high (∼400-500 mg/mL) concentration of crystallins in mature lens tissue and multiple other factors impede precise characterization of β-crystallin interactions, oligomer composition, size, and topology. Native ion mobility-mass spectrometry is used here to probe β-crystallin association and provide insight into homo- and heterooligomerization kinetics for these proteins. These experiments include separation and characterization of higher-order β-crystallin oligomers and illustrate the unique advantages of native IM-MS. Recombinantly expressed βB1, βB2, and βA3 isoforms are found to have different homodimerization propensities, and only βA3 forms larger homooligomers. Heterodimerization of βB2 with βA3 occurs ∼3 times as fast as that of βB1 with βA3, and βB1 and βB2 heterodimerize less readily. Ion mobility experiments, molecular dynamics simulations, and PISA analysis together reveal that observed oligomers are consistent with predominantly compact, ring-like topologies.
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Affiliation(s)
- Amber D Rolland
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA
| | - Takumi Takata
- Kyoto University, Research Reactor Institute 2, Asashiro-Nishi, Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
| | - Micah T Donor
- Department of Biological & Molecular Sciences, George Fox University, 414 N Meridian St, Newberg, OR 97132, USA
| | - Kirsten J Lampi
- Integrative Biosciences, School of Dentistry, 3181 SW Sam Jackson Park Road, Oregon Health & Science University, Portland, OR 97239-3098, USA.
| | - James S Prell
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene, OR 97403-1253, USA; Materials Science Institute, 1252 University of Oregon, Eugene, OR 97403-1252, USA.
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14
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Haack A, Ieritano C, Hopkins WS. MobCal-MPI 2.0: an accurate and parallelized package for calculating field-dependent collision cross sections and ion mobilities. Analyst 2023. [PMID: 37376881 DOI: 10.1039/d3an00545c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Ion mobility spectrometry (IMS), which can be employed as either a stand-alone instrument or coupled to mass spectrometry, has become an important tool for analytical chemistry. Because of the direct relation between an ion's mobility and its structure, which is intrinsically related to its collision cross section (CCS), IMS techniques can be used in tandem with computational tools to elucidate ion geometric structure. Here, we present MobCal-MPI 2.0, a software package that demonstrates excellent accuracy (RMSE 2.16%) and efficiency in calculating low-field CCSs via the trajectory method (≤30 minutes on 8 cores for ions with ≤70 atoms). MobCal-MPI 2.0 expands on its predecessor by enabling the calculation of high-field mobilities through the implementation of the 2nd order approximation to two-temperature theory (2TT). By further introducing an empirical correction to account for deviations between 2TT and experiment, MobCal-MPI 2.0 can compute accurate high-field mobilities that exhibit a mean deviation of <4% from experimentally measured values. Moreover, the velocities used to sample ion-neutral collisions were updated from a weighted to a linear grid, enabling the near-instantaneous evaluation of mobility/CCS at any effective temperature from a single set of N2 scattering trajectories. Several enhancements made to the code are also discussed, including updates to the statistical analysis of collision event sampling and benchmarking of overall performance.
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Affiliation(s)
- Alexander Haack
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
| | - Christian Ieritano
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
- Watermine Innovation, Waterloo, Ontario, N0B 2T0, Canada
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
- Watermine Innovation, Waterloo, Ontario, N0B 2T0, Canada
- Centre for Eye and Vision Research, Hong Kong Science Park, New Territories, 999077, Hong Kong
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15
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Luan M, Hou Z, Zhang B, Ma L, Yuan S, Liu Y, Huang G. Inter-Domain Repulsion of Dumbbell-Shaped Calmodulin during Electrospray Ionization Revealed by Molecular Dynamics Simulations. Anal Chem 2023; 95:8798-8806. [PMID: 37309130 DOI: 10.1021/acs.analchem.2c05630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The mechanisms whereby protein ions are released from nanodroplets at the liquid-gas interface have continued to be controversial since electrospray ionization (ESI) mass spectrometry was widely applied in biomolecular structure analysis in solution. Several viable pathways have been proposed and verified for single-domain proteins. However, the ESI mechanism of multi-domain proteins with more complicated and flexible structures remains unclear. Herein, dumbbell-shaped calmodulin was chosen as a multi-domain protein model to perform molecular dynamics simulations to investigate the structural evolution during the ESI process. For [Ca4CAM], the protein followed the classical charge residue model. As the inter-domain electrostatic repulsion increased, the droplet was found to split into two sub-droplets, while stronger-repulsive apo-calmodulin unfolded during the early evaporation stage. We designated this novel ESI mechanism as the domain repulsion model, which provides new mechanistic insights into further exploration of proteins containing more domains. Our results suggest that greater attention should be paid to the effect of domain-domain interactions on structure retention during liquid-gas interface transfer when mass spectrometry is used as the developing technique in gas phase structural biology.
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Affiliation(s)
- Moujun Luan
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Zhuanghao Hou
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Buchun Zhang
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Likun Ma
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Siming Yuan
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
- Department of Pharmacy, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Yangzhong Liu
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
- Department of Pharmacy, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Guangming Huang
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
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16
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Schultz M, Parker SL, Fernando MT, Wellalage MM, Thomas DA. Diserinol Isophthalamide: A Novel Reagent for Complexation with Biomolecular Anions in Electrospray Ionization Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:745-753. [PMID: 36975839 DOI: 10.1021/jasms.3c00010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Transferring biomolecules from solution to vacuum facilitates a detailed analysis of molecular structure and dynamics by isolating molecules of interest from a complex environment. However, inherent in the ion desolvation process is the loss of solvent hydrogen bonding partners, which are critical for the stability of a condensed-phase structure. Thus, transfer of ions to vacuum can favor structural rearrangement, especially near solvent-accessible charge sites, which tend to adopt intramolecular hydrogen bonding motifs in the absence of solvent. Complexation of monoalkylammonium moieties (e.g., lysine side chains) with crown ethers such as 18-crown-6 can disfavor structural rearrangement of protonated sites, but no equivalent ligand has been investigated for deprotonated groups. Herein we describe diserinol isophthalamide (DIP), a novel reagent for the gas-phase complexation of anionic moieties within biomolecules. Complexation is observed to the C-terminus or side chains of the small model peptides GD, GE, GG, DF-OMe, VYV, YGGFL, and EYMPME in electrospray ionization mass spectrometry (ESI-MS) studies. In addition, complexation is observed with the phosphate and carboxylate moieities of phosphoserine and phosphotyrosine. DIP performs favorably in comparison to an existing anion recognition reagent, 1,1'-(1,2-phenylene)bis(3-phenylurea), that exhibits moderate carboxylate binding in organic solvent. This improved performance in ESI-MS experiments is attributed to reduced steric constraints to complexation with carboxylate groups of larger molecules. Overall, diserinol isophthalamide is an effective complexation reagent that can be applied in future work to study retention of solution-phase structure, investigate intrinsic molecular properties, and examine solvation effects.
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Affiliation(s)
- Madeline Schultz
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Sarah L Parker
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Maleesha T Fernando
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Miyuru M Wellalage
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Daniel A Thomas
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island 02881, United States
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17
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Fu D, Habtegabir SG, Wang H, Feng S, Han Y. Understanding of protomers/deprotomers by combining mass spectrometry and computation. Anal Bioanal Chem 2023:10.1007/s00216-023-04574-1. [PMID: 36737499 DOI: 10.1007/s00216-023-04574-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/19/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023]
Abstract
Multifunctional compounds may form different prototropic isomers under different conditions, which are known as protomers/deprotomers. In biological systems, these protomer/deprotomer isomers affect the interaction modes and conformational landscape between compounds and enzymes and thus present different biological activities. Study on protomers/deprotomers is essentially the study on the acidity/basicity of each intramolecular functional group and its effect on molecular structure. In recent years, the combination of mass spectrometry (MS) and computational chemistry has been proven to be a powerful and effective means to study prototropic isomers. MS-based technologies are developed to discriminate and characterize protomers/deprotomers to provide structural information and monitor transformations, showing great superiority than other experimental methods. Computational chemistry is used to predict the thermodynamic stability of protomers/deprotomers, provide the simulated MS/MS spectra, infrared spectra, and calculate collision cross-section values. By comparing the theoretical data with the corresponding experimental results, the researchers can not only determine the protomer/deprotomer structure, but also investigate the structure-activity relationship in a given system. This review covers various MS methods and theoretical calculations and their devotion to isomer discrimination, structure identification, conformational transformation, and phase transition investigation of protomers/deprotomers.
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Affiliation(s)
- Dali Fu
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Sara Girmay Habtegabir
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Haodong Wang
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Shijie Feng
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Yehua Han
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China.
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18
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Cropley TC, Chai M, Liu FC, Bleiholder C. Perspective on the potential of tandem-ion mobility /mass spectrometry methods for structural proteomics applications. FRONTIERS IN ANALYTICAL SCIENCE 2023; 3:1106752. [PMID: 37333518 PMCID: PMC10273136 DOI: 10.3389/frans.2023.1106752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Cellular processes are usually carried out collectively by the entirety of all proteins present in a biological cell, i.e. the proteome. Mass spectrometry-based methods have proven particularly successful in identifying and quantifying the constituent proteins of proteomes, including different molecular forms of a protein. Nevertheless, protein sequences alone do not reveal the function or dysfunction of the identified proteins. A straightforward way to assign function or dysfunction to proteins is characterization of their structures and dynamics. However, a method capable to characterize detailed structures of proteins and protein complexes in a large-scale, systematic manner within the context of cellular processes does not yet exist. Here, we discuss the potential of tandem-ion mobility / mass spectrometry (tandem-IM/MS) methods to provide such ability. We highlight the capability of these methods using two case studies on the protein systems ubiquitin and avidin using the tandem-TIMS/MS technology developed in our laboratory and discuss these results in the context of other developments in the broader field of tandem-IM/MS.
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Affiliation(s)
- Tyler C. Cropley
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - Mengqi Chai
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
- Department of Chemistry, Washington University in St. Louis, Saint-Louis, Missouri, USA
| | - Fanny C. Liu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
| | - Christian Bleiholder
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, USA
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA
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19
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Khristenko N, Rosu F, Largy E, Haustant J, Mesmin C, Gabelica V. Native Electrospray Ionization of Multi-Domain Proteins via a Bead Ejection Mechanism. J Am Chem Soc 2023; 145:498-506. [PMID: 36573911 DOI: 10.1021/jacs.2c10762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Native ion mobility mass spectrometry is potentially useful for the biophysical characterization of proteins, as the electrospray charge state distribution and the collision cross section distribution depend on their solution conformation. We examine here the charging and gas-phase conformation of multi-domain therapeutic proteins comprising globular domains tethered by disordered linkers. The charge and collision cross section distributions are multimodal, suggesting several conformations in solution, as confirmed by solution hydrogen/deuterium exchange. The most intriguing question is the ionization mechanism of these structures: a fraction of the population does not follow the charged residue mechanism but cannot ionize by pure chain ejection either. We deduce that a hybrid mechanism is possible, wherein globular domains are ejected one at a time from a parent droplet. The charge vs solvent accessible surface area correlations of denatured and intrinsically disordered proteins are also compatible with this "bead ejection mechanism", which we propose as a general tenet of biomolecule electrospray.
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Affiliation(s)
- Nina Khristenko
- Université de Bordeaux, CNRS, INSERM, ARNA, UMR5320, U1212, IECB, PessacF-33600, France
| | - Frédéric Rosu
- Université de Bordeaux, CNRS, INSERM, IECB, UAR3033, US01, PessacF-33600, France
| | - Eric Largy
- Université de Bordeaux, CNRS, INSERM, ARNA, UMR5320, U1212, IECB, PessacF-33600, France
| | - Jérôme Haustant
- Merck Biodevelopment SAS/An Affiliate of Merck KGaA - Darmstadt, Germany, MartillacF-33650, France
| | - Cédric Mesmin
- Merck Biodevelopment SAS/An Affiliate of Merck KGaA - Darmstadt, Germany, MartillacF-33650, France
| | - Valérie Gabelica
- Université de Bordeaux, CNRS, INSERM, ARNA, UMR5320, U1212, IECB, PessacF-33600, France.,Université de Bordeaux, CNRS, INSERM, IECB, UAR3033, US01, PessacF-33600, France
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20
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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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21
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Eldrid C, Cragnolini T, Ben-Younis A, Zou J, Raleigh DP, Thalassinos K. Linking Gas-Phase and Solution-Phase Protein Unfolding via Mobile Proton Simulations. Anal Chem 2022; 94:16113-16121. [DOI: 10.1021/acs.analchem.2c03352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Charles Eldrid
- School of Biological Sciences, University of Southampton, SouthamptonSO16 1BJ, U.K
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, LondonWC1E 6BT, U.K
| | - Tristan Cragnolini
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, LondonWC1E 7HX, U.K
| | - Aisha Ben-Younis
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, LondonWC1E 6BT, U.K
| | - Junjie Zou
- Department of Chemistry, Stony Brook University, 100 Nicolls Rd., Stony Brook, New York11794, United States
| | - Daniel P. Raleigh
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, LondonWC1E 6BT, U.K
- Department of Chemistry, Stony Brook University, 100 Nicolls Rd., Stony Brook, New York11794, United States
| | - Konstantinos Thalassinos
- Institute of Structural and Molecular Biology, Division of Bioscience, University College London, LondonWC1E 6BT, U.K
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, LondonWC1E 7HX, U.K
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22
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Stability and conformational memory of electrosprayed and rehydrated bacteriophage MS2 virus coat proteins. Curr Res Struct Biol 2022; 4:338-348. [PMID: 36440379 PMCID: PMC9685359 DOI: 10.1016/j.crstbi.2022.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/23/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022] Open
Abstract
Proteins are innately dynamic, which is important for their functions, but which also poses significant challenges when studying their structures. Gas-phase techniques can utilise separation and a range of sample manipulations to transcend some of the limitations of conventional techniques for structural biology in crystalline or solution phase, and isolate different states for separate interrogation. However, the transfer from solution to the gas phase risks affecting the structures, and it is unclear to what extent different conformations remain distinct in the gas phase, and if resolution in silico can recover the native conformations and their differences. Here, we use extensive molecular dynamics simulations to study the two distinct conformations of dimeric capsid protein of the MS2 bacteriophage. The protein undergoes notable restructuring of its peripheral parts in the gas phase, but subsequent simulation in solvent largely recovers the native structure. Our results suggest that despite some structural loss due to the experimental conditions, gas-phase structural biology techniques provide meaningful data that inform not only about the structures but also conformational dynamics of proteins. Presented extensive molecular dynamics (MD) simulation data investigating protein vacuum exposure and rehydration dynamics. Demonstrated that the majority of the protein structure recovers their initial solution conformation after vacuum exposure. Explored the potential gain for structural biology of using MD simulation to refine gas-phase determined protein structures.
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23
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Santambrogio C, Ponzini E, Grandori R. Native mass spectrometry for the investigation of protein structural (dis)order. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140828. [PMID: 35926718 DOI: 10.1016/j.bbapap.2022.140828] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 06/24/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
A central challenge in structural biology is represented by dynamic and heterogeneous systems, as typically represented by proteins in solution, with the extreme case of intrinsically disordered proteins (IDPs) [1-3]. These proteins lack a specific three-dimensional structure and have poorly organized secondary structure. For these reasons, they escape structural characterization by conventional biophysical methods. The investigation of these systems requires description of conformational ensembles, rather than of unique, defined structures or bundles of largely superimposable structures. Mass spectrometry (MS) has become a central tool in this field, offering a variety of complementary approaches to generate structural information on either folded or disordered proteins [4-6]. Two main categories of methods can be recognized. On one side, conformation-dependent reactions (such as cross-linking, covalent labeling, H/D exchange) are exploited to label molecules in solution, followed by the characterization of the labeling products by denaturing MS [7-11]. On the other side, non-denaturing ("native") MS can be used to directly explore the different conformational components in terms of geometry and structural compactness [12-16]. All these approaches have in common the capability to conjugate protein structure investigation with the peculiar analytical power of MS measurements, offering the possibility of assessing species distributions for folding and binding equilibria and the combination of both. These methods can be combined with characterization of noncovalent complexes [17, 18] and post-translational modifications [19-23]. This review focuses on the application of native MS to protein structure and dynamics investigation, with a general methodological section, followed by examples on specific proteins from our laboratory.
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Affiliation(s)
- Carlo Santambrogio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
| | - Erika Ponzini
- Materials Science Department, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milan, Italy; COMiB Research Center, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milan, Italy
| | - Rita Grandori
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
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24
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Österlund N, Vosselman T, Leppert A, Gräslund A, Jörnvall H, Ilag LL, Marklund EG, Elofsson A, Johansson J, Sahin C, Landreh M. Mass Spectrometry and Machine Learning Reveal Determinants of Client Recognition by Antiamyloid Chaperones. Mol Cell Proteomics 2022; 21:100413. [PMID: 36115577 PMCID: PMC9563204 DOI: 10.1016/j.mcpro.2022.100413] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/08/2022] [Accepted: 09/11/2022] [Indexed: 01/18/2023] Open
Abstract
The assembly of proteins and peptides into amyloid fibrils is causally linked to serious disorders such as Alzheimer's disease. Multiple proteins have been shown to prevent amyloid formation in vitro and in vivo, ranging from highly specific chaperone-client pairs to completely nonspecific binding of aggregation-prone peptides. The underlying interactions remain elusive. Here, we turn to the machine learning-based structure prediction algorithm AlphaFold2 to obtain models for the nonspecific interactions of β-lactoglobulin, transthyretin, or thioredoxin 80 with the model amyloid peptide amyloid β and the highly specific complex between the BRICHOS chaperone domain of C-terminal region of lung surfactant protein C and its polyvaline target. Using a combination of native mass spectrometry (MS) and ion mobility MS, we show that nonspecific chaperoning is driven predominantly by hydrophobic interactions of amyloid β with hydrophobic surfaces in β-lactoglobulin, transthyretin, and thioredoxin 80, and in part regulated by oligomer stability. For C-terminal region of lung surfactant protein C, native MS and hydrogen-deuterium exchange MS reveal that a disordered region recognizes the polyvaline target by forming a complementary β-strand. Hence, we show that AlphaFold2 and MS can yield atomistic models of hard-to-capture protein interactions that reveal different chaperoning mechanisms based on separate ligand properties and may provide possible clues for specific therapeutic intervention.
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Affiliation(s)
- Nicklas Österlund
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Thibault Vosselman
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Axel Leppert
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Astrid Gräslund
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Hans Jörnvall
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Leopold L. Ilag
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden
| | - Erik G. Marklund
- Department of Chemistry - BMC, Uppsala University, Uppsala, Sweden
| | - Arne Elofsson
- Science for Life Laboratory and Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
| | - Jan Johansson
- Department of Biosciences and Nutrition, Karolinska Institutet, Neo, Huddinge, Sweden
| | - Cagla Sahin
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden,Department of Biology, University of Copenhagen, Denmark,For correspondence: Michael Landreh; Cagla Sahin
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden,For correspondence: Michael Landreh; Cagla Sahin
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25
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Cheung See Kit M, Webb IK. Application of Multiple Length Cross-linkers to the Characterization of Gaseous Protein Structure. Anal Chem 2022; 94:13301-13310. [DOI: 10.1021/acs.analchem.2c03044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Melanie Cheung See Kit
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Ian K. Webb
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202, United States
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26
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NMR analysis suggests the terminal domains of Robo1 remain extended but are rigidified in the presence of heparan sulfate. Sci Rep 2022; 12:14769. [PMID: 36042257 PMCID: PMC9427851 DOI: 10.1038/s41598-022-18769-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 08/18/2022] [Indexed: 11/19/2022] Open
Abstract
Human roundabout 1 (hRobo1) is an extracellular receptor glycoprotein that plays important roles in angiogenesis, organ development, and tumor progression. Interaction between hRobo1 and heparan sulfate (HS) has been shown to be essential for its biological activity. To better understand the effect of HS binding we engineered a lanthanide-binding peptide sequence (Loop) into the Ig2 domain of hRobo1. Native mass spectrometry was used to verify that loop introduction did not inhibit HS binding or conformational changes previously suggested by gas phase ion mobility measurements. NMR experiments measuring long-range pseudocontact shifts were then performed on 13C-methyl labeled hRobo1-Ig1-2-Loop in HS-bound and unbound forms. The magnitude of most PCSs for methyl groups in the Ig1 domain increase in the bound state confirming a change in the distribution of interdomain geometries. A grid search over Ig1 orientations to optimize the fit of data to a single conformer for both forms produced two similar structures, both of which differ from existing X-ray crystal structures and structures inferred from gas-phase ion mobility measurements. The structures and degree of fit suggest that the hRobo1-Ig1-2 structure changes slightly and becomes more rigid on HS binding. This may have implications for Robo-Slit signaling.
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27
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Turzo SMBA, Seffernick JT, Rolland AD, Donor MT, Heinze S, Prell JS, Wysocki VH, Lindert S. Protein shape sampled by ion mobility mass spectrometry consistently improves protein structure prediction. Nat Commun 2022; 13:4377. [PMID: 35902583 PMCID: PMC9334640 DOI: 10.1038/s41467-022-32075-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 07/14/2022] [Indexed: 11/09/2022] Open
Abstract
Ion mobility (IM) mass spectrometry provides structural information about protein shape and size in the form of an orientationally-averaged collision cross-section (CCSIM). While IM data have been used with various computational methods, they have not yet been utilized to predict monomeric protein structure from sequence. Here, we show that IM data can significantly improve protein structure determination using the modelling suite Rosetta. We develop the Rosetta Projection Approximation using Rough Circular Shapes (PARCS) algorithm that allows for fast and accurate prediction of CCSIM from structure. Following successful testing of the PARCS algorithm, we use an integrative modelling approach to utilize IM data for protein structure prediction. Additionally, we propose a confidence metric that identifies near native models in the absence of a known structure. The results of this study demonstrate the ability of IM data to consistently improve protein structure prediction. Collision cross sections (CCS) from ion mobility mass spectrometry provide information about protein shape and size. Here, the authors develop an algorithm to predict CCS and integrate experimental ion mobility data into Rosetta-based molecular modelling to predict protein structures from sequence.
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Affiliation(s)
- S M Bargeen Alam Turzo
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, Ohio State University, Columbus, OH, 43210, USA
| | - Justin T Seffernick
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, Ohio State University, Columbus, OH, 43210, USA
| | - Amber D Rolland
- Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR, 97403, USA
| | - Micah T Donor
- Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR, 97403, USA
| | - Sten Heinze
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, Ohio State University, Columbus, OH, 43210, USA
| | - James S Prell
- Department of Chemistry and Biochemistry and Materials Science Institute, University of Oregon, Eugene, OR, 97403, USA
| | - Vicki H Wysocki
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, Ohio State University, Columbus, OH, 43210, USA
| | - Steffen Lindert
- Department of Chemistry and Biochemistry and Resource for Native Mass Spectrometry Guided Structural Biology, Ohio State University, Columbus, OH, 43210, USA.
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28
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Vallejo DD, Jeon CK, Parson KF, Herderschee HR, Eschweiler JD, Filoti DI, Ruotolo BT. Ion Mobility-Mass Spectrometry Reveals the Structures and Stabilities of Biotherapeutic Antibody Aggregates. Anal Chem 2022; 94:6745-6753. [PMID: 35475624 DOI: 10.1021/acs.analchem.2c00160] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Stability is a key critical quality attribute monitored throughout the development of monoclonal antibody (mAb) therapeutics. Minor changes in their higher order structure (HOS) caused by stress or environment may alter mAb aggregation, immunogenicity, and efficacy. In addition, the structures of the resulting mAb aggregates are largely unknown, as are their dependencies on conditions under which they are created. In this report, we investigate the HOS of mAb monomers and dimers under a variety of forced degradation conditions with ion mobility-mass spectrometry (IM-MS) and collision-induced unfolding (CIU) technologies. We evaluate two model IgG1 antibodies that differ significantly only in their complementarity-determinant regions: IgG1α and IgG1β. Our data covering both heat- and pH-based forced degradation conditions, aquired on two different IM-MS platforms, show that these mAbs undergo global HOS changes at both monomer and dimer levels upon degradation, but shifts in collision cross section (CCS) differ under pH or heat degradation conditions. In addition, the level of CCS change detected is different between IgG1α and IgG1β, suggesting that differences in the CDR drive differential responses to degradation that influence the antibody HOS. Dramatically different CIU fingerprints are obtained for IgG1α and IgG1β monomers and dimers for both degradation conditions. Finally, we constructed a series of computational models of mAb dimers for comparison with experimental CCS values and found evidence for a compact, overlapped dimer structure under native and heat degradation conditions, possibly adopting an inverted or nonoverlapped quaternary structure when produced through pH degredation. We conclude by discussing the potential impact of our findings on ongoing biotherapeutic discovery and development efforts.
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Affiliation(s)
- Daniel D Vallejo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Chae Kyung Jeon
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kristine F Parson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hayley R Herderschee
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Dana I Filoti
- AbbVie, North Chicago, Illinois 60064, United States
| | - Brandon T Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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29
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Yen HY, Abramsson ML, Agasid MT, Lama D, Gault J, Liko I, Kaldmäe M, Saluri M, Qureshi AA, Suades A, Drew D, Degiacomi MT, Marklund EG, Allison TM, Robinson CV, Landreh M. Electrospray ionization of native membrane proteins proceeds via a charge equilibration step. RSC Adv 2022; 12:9671-9680. [PMID: 35424940 PMCID: PMC8972943 DOI: 10.1039/d2ra01282k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/21/2022] [Indexed: 11/21/2022] Open
Abstract
Electrospray ionization mass spectrometry is increasingly applied to study the structures and interactions of membrane protein complexes. However, the charging mechanism is complicated by the presence of detergent micelles during ionization. Here, we show that the final charge of membrane proteins can be predicted by their molecular weight when released from the non-charge reducing saccharide detergents. Our data indicate that PEG detergents lower the charge depending on the number of detergent molecules in the surrounding micelle, whereas fos-choline detergents may additionally participate in ion–ion reactions after desolvation. The supercharging reagent sulfolane, on the other hand, has no discernible effect on the charge of detergent-free membrane proteins. Taking our observations into the context of protein-detergent interactions in the gas phase, we propose a charge equilibration model for the generation of native-like membrane protein ions. During ionization of the protein-detergent complex, the ESI charges are distributed between detergent and protein according to proton affinity of the detergent, number of detergent molecules, and surface area of the protein. Charge equilibration influenced by detergents determines the final charge state of membrane proteins. This process likely contributes to maintaining a native-like fold after detergent release and can be harnessed to stabilize particularly labile membrane protein complexes in the gas phase. The electrospray ionization mechanism contributes to preserving the structures and interactions of membrane protein complexes in native mass spectrometry.![]()
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Affiliation(s)
- Hsin-Yung Yen
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK .,Institute of Biological Chemistry, Academia Sinica 128, Academia Road Sec. 2, Nankang Taipei 115 Taiwan
| | - Mia L Abramsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Mark T Agasid
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Dilraj Lama
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Joseph Gault
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Idlir Liko
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Margit Kaldmäe
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Mihkel Saluri
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Abdul Aziz Qureshi
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK .,Department of Biochemistry and Biophysics, Stockholm University 10691 Stockholm Sweden
| | - Albert Suades
- Department of Biochemistry and Biophysics, Stockholm University 10691 Stockholm Sweden
| | - David Drew
- Department of Biochemistry and Biophysics, Stockholm University 10691 Stockholm Sweden
| | | | - Erik G Marklund
- Department of Chemistry - BMC, Uppsala University Box 576 75123 Uppsala Sweden
| | - Timothy M Allison
- Biomolecular Interaction Centre, School of Physical and Chemical Sciences, University of Canterbury Christchurch 8140 New Zealand
| | - Carol V Robinson
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
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30
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Lee JU, Lee ST, Park CR, Moon B, Kim HI, Oh HB. TEMPO-Assisted Free-Radical-Initiated Peptide Sequencing Mass Spectrometry for Ubiquitin Ions: An Insight on the Gas-Phase Conformations. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:471-481. [PMID: 35099967 DOI: 10.1021/jasms.1c00313] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
TEMPO ((2,2,6,6-tetramethylpiperidine-1-yl)oxyl)-assisted free-radical-initiated peptide sequencing mass spectrometry (FRIPS MS) is applied to the top-down tandem mass spectrometry of guanidinated ubiquitin (UB(Gu)) ions, i.e., p-TEMPO-Bn-Sc-guanidinated ubiquitin (UBT(Gu)), to shed a light on gas-phase ubiquitin conformations. Thermal activation of UBT(Gu) ions produced protein backbone fragments of radical character, i.e., a-/x- and c-/z-type fragments. It is in contrast to the collision-induced dissociation (CID) results for UB(Gu), which dominantly showed the specific charge-remote CID fragments of b-/y-type at the C-terminal side of glutamic acid (E) and aspartic acid (D). The transfer of a radical "through space" was mainly observed for the +5 and +6 UBT(Gu) ions. This provides the information about folding/unfolding and structural proximity between the positions of the incipient benzyl radical site and fragmented sites. The analysis of FRIPS MS results for the +5 charge state ubiquitin ions shows that the +5 charge state ubiquitin ions bear a conformational resemblance to the native ubiquitin (X-ray crystallography structure), particularly in the central sequence region, whereas some deviations were observed in the unstable second structure region (β2) close to the N-terminus. The ion mobility spectrometry results also corroborate the FRIPS MS results in terms of their conformations (or structures). The experimental results obtained in this study clearly demonstrate a potential of the TEMPO-assisted FRIPS MS as one of the methods for the elucidation of the overall gas-phase protein structures.
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Affiliation(s)
- Jae-Ung Lee
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Sang Tak Lee
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Chae Ri Park
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Bongjin Moon
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
| | - Hugh I Kim
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Han Bin Oh
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea
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31
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Rolland AD, Biberic LS, Prell JS. Investigation of Charge-State-Dependent Compaction of Protein Ions with Native Ion Mobility-Mass Spectrometry and Theory. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:369-381. [PMID: 35073092 DOI: 10.1021/jasms.1c00351] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The precise relationship between native gas-phase protein ion structure, charge, desolvation, and activation remains elusive. Much evidence supports the Charge Residue Model for native protein ions formed by electrospray ionization, but scaling laws derived from it relate only to overall ion size. Closer examination of drift tube CCSs across individual native protein ion charge state distributions (CSDs) reveals deviations from global trends. To investigate whether this is due to structure variation across CSDs or contributions of long-range charge-dipole interactions, we performed in vacuo force field molecular dynamics (MD) simulations of multiple charge conformers of three proteins representing a variety of physical and structural features: β-lactoglobulin, concanavalin A, and glutamate dehydrogenase. Results from these simulated ions indicate subtle structure variation across their native CSDs, although effects of these structural differences and long-range charge-dependent interactions on CCS are small. The structure and CCS of smaller proteins may be more sensitive to charge due to their low surface-to-volume ratios and reduced capacity to compact. Secondary and higher order structure from condensed-phase structures is largely retained in these simulations, supporting the use of the term "native-like" to describe results from native ion mobility-mass spectrometry experiments, although, notably, the most compact structure can be the most different from the condensed-phase structure. Collapse of surface side chains to self-solvate through formation of new hydrogen bonds is a major feature of gas-phase compaction and likely occurs during the desolvation process. Results from these MD simulations provide new insight into the relationship of gas-phase protein ion structure, charge, and CCS.
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Affiliation(s)
- Amber D Rolland
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Lejla S Biberic
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403-1253, United States
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403-1253, United States
- Materials Science Institute, University of Oregon, 1252 University of Oregon, Eugene, Oregon 97403-1252, United States
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32
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Swansiger AK, Marty MT, Prell JS. Fourier-Transform Approach for Reconstructing Macromolecular Mass Defect Profiles. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:172-180. [PMID: 34913687 DOI: 10.1021/jasms.1c00317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
State-of-the-art native mass spectrometry (MS) methods have been developed for analysis of highly heterogeneous intact complexes and have provided much insight into the structure and properties of noncovalent assemblies that can be difficult to study using denatured proteins. These native MS methods can often be used to study even highly polydisperse membrane proteins embedded in detergent micelles, nanodiscs, and other membrane mimics. However, characterizing highly polydisperse native complexes which are also heterogeneous presents additional challenges for native MS. Macromolecular mass defect (MMD) analysis aims to characterize heterogeneous ion populations obfuscated by adduct polydispersity and reveal the distribution of "base" masses, and was recently implemented in the Bayesian analysis software UniDec. Here, we illustrate an alternative, orthogonal MMD analysis method implemented in the deconvolution program iFAMS, which takes advantage of Fourier transform (FT) to deconvolve low-resolution data with few user-input parameters and which can provide high quality results even for mass spectra with a signal-to-noise ratio of ∼5:1. Agreement between this method, which is based on frequency-domain data, and the mass-domain algorithm of UniDec provides strong evidence that both methods can accurately characterize highly polydisperse and heterogeneous ion populations. The FT algorithm is expected to be very useful in characterizing many types of analytes ranging from membrane proteins to polymer-conjugated proteins, branched polymers, and other large analytes, as well as for reconstructing isotope profiles for highly complex but still isotope-resolved mass spectra.
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Affiliation(s)
- Andrew K Swansiger
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - Michael T Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
- Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1252, United States
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33
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Townsend JA, Sanders HM, Rolland AD, Park CK, Horton NC, Prell JS, Wang J, Marty MT. Influenza AM2 Channel Oligomerization Is Sensitive to Its Chemical Environment. Anal Chem 2021; 93:16273-16281. [PMID: 34813702 DOI: 10.1021/acs.analchem.1c04660] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Viroporins are small viral ion channels that play important roles in the viral infection cycle and are proven antiviral drug targets. Matrix protein 2 from influenza A (AM2) is the best-characterized viroporin, and the current paradigm is that AM2 forms monodisperse tetramers. Here, we used native mass spectrometry and other techniques to characterize the oligomeric state of both the full-length and transmembrane (TM) domain of AM2 in a variety of different pH and detergent conditions. Unexpectedly, we discovered that AM2 formed a range of different oligomeric complexes that were strongly influenced by the local chemical environment. Native mass spectrometry of AM2 in nanodiscs with different lipids showed that lipids also affected the oligomeric states of AM2. Finally, nanodiscs uniquely enabled the measurement of amantadine binding stoichiometries to AM2 in the intact lipid bilayer. These unexpected results reveal that AM2 can form a wider range of oligomeric states than previously thought possible, which may provide new potential mechanisms of influenza pathology and pharmacology.
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Affiliation(s)
- Julia A Townsend
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Henry M Sanders
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Amber D Rolland
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403, United States.,Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Chad K Park
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, United States
| | - Nancy C Horton
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, United States
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403, United States.,Materials Science Institute, University of Oregon, Eugene, Oregon 97403, United States
| | - Jun Wang
- Department of Pharmacology and Toxicology, The University of Arizona, Tucson, Arizona 85721, United States.,Bio5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
| | - Michael T Marty
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States.,Bio5 Institute, The University of Arizona, Tucson, Arizona 85721, United States
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34
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Abstract
Recent advancements place a comprehensive catalog of protein structure, oligomeric state, sequence, and modification status tentatively within reach, thus providing an unprecedented roadmap to therapies for many human diseases. To achieve this goal, revolutionary technologies capable of bridging key gaps in our ability to simultaneously measure protein composition and structure must be developed. Much of the current progress in this area has been catalyzed by mass spectrometry (MS) tools, which have become an indispensable resource for interrogating the structural proteome. For example, methods associated with native proteomics seek to comprehensively capture and quantify the endogenous assembly states for all proteins within an organism. Such technologies have often been partnered with ion mobility (IM) separation, from which collision cross section (CCS) information can be rapidly extracted to provide protein size information. IM technologies are also being developed that utilize CCS values to enhance the confidence of protein identification workflows derived from liquid chromatography-IM-MS analyses of enzymatically produced peptide mixtures. Such parallel advancements in technology beg the question: can CCS values prove similarly useful for the identification of intact proteins and their complexes in native proteomics? In this perspective, I examine current evidence and technology trends to explore the promise and limitations of such CCS information for the comprehensive analysis of multiprotein complexes from cellular mixtures.
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Affiliation(s)
- Brandon T Ruotolo
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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35
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Donor MT, Wilson JW, Shepherd SO, Prell JS. Lipid Head Group Adduction to Soluble Proteins Follows Gas-Phase Basicity Predictions: Dissociation Barriers and Charge Abstraction. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2021; 469:116670. [PMID: 34421332 PMCID: PMC8372978 DOI: 10.1016/j.ijms.2021.116670] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Native mass spectrometry analysis of membrane proteins has yielded many useful insights in recent years with respect to membrane protein-lipid interactions, including identifying specific interactions and even measuring binding affinities based on observed abundances of lipid-bound ions after collision-induced dissociation (CID). However, the behavior of non-covalent complexes subjected to extensive CID can in principle be affected by numerous factors related to gas-phase chemistry, including gas-phase basicity (GB) and acidity, shared-proton bonds, and other factors. A recent report from our group showed that common lipids span a wide range of GB values. Notably, phosphatidylcholine (PC) and sphingomyelin lipids are more basic than arginine, suggesting they may strip charge upon dissociation in positive ion mode, while phosphoserine lipids are slightly less basic than arginine and may form especially strong shared-proton bonds. Here, we use CID to probe the strength of non-specific gas-phase interactions between lipid head groups and several soluble proteins, used to deliberately avoid possible physiological protein-lipid interactions. The strengths of the protein-head group interactions follow the trend predicted based solely on lipid and amino acid GBs: phosphoserine (PS) head group forms the strongest bonds with these proteins and out-competes the other head groups studied, while glycerophosphocholine (GPC) head groups form the weakest interactions and dissociate carrying away a positive charge. These results indicate that gas-phase thermochemistry can play an important role in determining which head groups remain bound to protein ions with native-like structures and charge states in positive ion mode upon extensive collisional activation.
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Affiliation(s)
- Micah T. Donor
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
| | - Jesse W. Wilson
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
| | - Samantha O. Shepherd
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
| | - James S. Prell
- Department of Chemistry and Biochemistry, 1253 University of Oregon, Eugene OR 97403-1253
- Materials Science Institute, University of Oregon, 1252 University of Oregon, Eugene, OR 97403-1252
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36
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Lloyd Williams OH, Rijs NJ. Reaction Monitoring and Structural Characterisation of Coordination Driven Self-Assembled Systems by Ion Mobility-Mass Spectrometry. Front Chem 2021; 9:682743. [PMID: 34169059 PMCID: PMC8217442 DOI: 10.3389/fchem.2021.682743] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/14/2021] [Indexed: 01/03/2023] Open
Abstract
Nature creates exquisite molecular assemblies, required for the molecular-level functions of life, via self-assembly. Understanding and harnessing these complex processes presents an immense opportunity for the design and fabrication of advanced functional materials. However, the significant industrial potential of self-assembly to fabricate highly functional materials is hampered by a lack of knowledge of critical reaction intermediates, mechanisms, and kinetics. As we move beyond the covalent synthetic regime, into the domain of non-covalent interactions occupied by self-assembly, harnessing and embracing complexity is a must, and non-targeted analyses of dynamic systems are becoming increasingly important. Coordination driven self-assembly is an important subtype of self-assembly that presents several wicked analytical challenges. These challenges are "wicked" due the very complexity desired confounding the analysis of products, intermediates, and pathways, therefore limiting reaction optimisation, tuning, and ultimately, utility. Ion Mobility-Mass Spectrometry solves many of the most challenging analytical problems in separating and analysing the structure of both simple and complex species formed via coordination driven self-assembly. Thus, due to the emerging importance of ion mobility mass spectrometry as an analytical technique tackling complex systems, this review highlights exciting recent applications. These include equilibrium monitoring, structural and dynamic analysis of previously analytically inaccessible complex interlinked structures and the process of self-sorting. The vast and largely untapped potential of ion mobility mass spectrometry to coordination driven self-assembly is yet to be fully realised. Therefore, we also propose where current analytical approaches can be built upon to allow for greater insight into the complexity and structural dynamics involved in self-assembly.
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Affiliation(s)
| | - Nicole J. Rijs
- School of Chemistry, UNSW Sydney, Sydney, NSW, Australia
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37
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McCabe JW, Hebert MJ, Shirzadeh M, Mallis CS, Denton JK, Walker TE, Russell DH. THE IMS PARADOX: A PERSPECTIVE ON STRUCTURAL ION MOBILITY-MASS SPECTROMETRY. MASS SPECTROMETRY REVIEWS 2021; 40:280-305. [PMID: 32608033 PMCID: PMC7989064 DOI: 10.1002/mas.21642] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/03/2020] [Indexed: 05/06/2023]
Abstract
Studies of large proteins, protein complexes, and membrane protein complexes pose new challenges, most notably the need for increased ion mobility (IM) and mass spectrometry (MS) resolution. This review covers evolutionary developments in IM-MS in the authors' and key collaborators' laboratories with specific focus on developments that enhance the utility of IM-MS for structural analysis. IM-MS measurements are performed on gas phase ions, thus "structural IM-MS" appears paradoxical-do gas phase ions retain their solution phase structure? There is growing evidence to support the notion that solution phase structure(s) can be retained by the gas phase ions. It should not go unnoticed that we use "structures" in this statement because an important feature of IM-MS is the ability to deal with conformationally heterogeneous systems, thus providing a direct measure of conformational entropy. The extension of this work to large proteins and protein complexes has motivated our development of Fourier-transform IM-MS instruments, a strategy first described by Hill and coworkers in 1985 (Anal Chem, 1985, 57, pp. 402-406) that has proved to be a game-changer in our quest to merge drift tube (DT) and ion mobility and the high mass resolution orbitrap MS instruments. DT-IMS is the only method that allows first-principles determinations of rotationally averaged collision cross sections (CSS), which is essential for studies of biomolecules where the conformational diversities of the molecule precludes the use of CCS calibration approaches. The Fourier transform-IM-orbitrap instrument described here also incorporates the full suite of native MS/IM-MS capabilities that are currently employed in the most advanced native MS/IM-MS instruments. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Jacob W McCabe
- Department of Chemistry, Texas A&M University, College Station, TX, 77843
| | - Michael J Hebert
- Department of Chemistry, Texas A&M University, College Station, TX, 77843
| | - Mehdi Shirzadeh
- Department of Chemistry, Texas A&M University, College Station, TX, 77843
| | | | - Joanna K Denton
- Department of Chemistry, Texas A&M University, College Station, TX, 77843
| | - Thomas E Walker
- Department of Chemistry, Texas A&M University, College Station, TX, 77843
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, TX, 77843
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38
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Kit MCS, Carvalho VV, Vilseck JZ, Webb IK. Gas-Phase Ion/Ion Chemistry for Structurally Sensitive Probes of Gaseous Protein Ion Structure: Electrostatic and Electrostatic to Covalent Cross-Linking. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2021; 463:116549. [PMID: 33716558 PMCID: PMC7946065 DOI: 10.1016/j.ijms.2021.116549] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Intramolecular interactions within a protein are key in maintaining protein tertiary structure and understanding how proteins function. Ion mobility-mass spectrometry (IM-MS) has become a widely used approach in structural biology since it provides rapid measurements of collision cross sections (CCS), which inform on the gas-phase conformation of the biomolecule under study. Gas-phase ion/ion reactions target amino acid residues with specific chemical properties and the modified sites can be identified by MS. In this study, electrostatically reactive, gas-phase ion/ion chemistry and IM-MS are combined to characterize the structural changes between ubiquitin electrosprayed from aqueous and denaturing conditions. The electrostatic attachment of sulfo-NHS acetate to ubiquitin via ion/ion reactions and fragmentation by electron-capture dissociation (ECD) provide the identification of the most accessible protonated sites within ubiquitin as the sulfonate group forms an electrostatic complex with accessible protonated side chains. The protonated sites identified by ECD from the different solution conditions are distinct and, in some cases, reflect the disruption of interactions such as salt bridges that maintain the native protein structure. This agrees with previously published literature demonstrating that a high methanol concentration at low pH causes the structure of ubiquitin to change from a native (N) state to a more elongated A state. Results using gas-phase, electrostatic cross-linking reagents also point to similar structural changes and further confirm the role of methanol and acid in favoring a more unfolded conformation. Since cross-linking reagents have a distance constraint for the two reactive sites, the data is valuable in guiding computational structures generated by molecular dynamics. The research presented here describes a promising strategy that can detect subtle changes in the local environment of targeted amino acid residues to inform on changes in the overall protein structure.
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Affiliation(s)
- Melanie Cheung See Kit
- Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
| | - Veronica V. Carvalho
- Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
| | - Jonah Z. Vilseck
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Ian K. Webb
- Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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39
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Ieritano C, Rickert D, Featherstone J, Honek JF, Campbell JL, Blanc JCYL, Schneider BB, Hopkins WS. The Charge-State and Structural Stability of Peptides Conferred by Microsolvating Environments in Differential Mobility Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:956-968. [PMID: 33733774 DOI: 10.1021/jasms.0c00469] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The presence of solvent vapor in a differential mobility spectrometry (DMS) cell creates a microsolvating environment that can mitigate complications associated with field-induced heating. In the case of peptides, the microsolvation of protonation sites results in a stabilization of charge density through localized solvent clustering, sheltering the ion from collisional activation. Seeding the DMS carrier gas (N2) with a solvent vapor prevented nearly all field-induced fragmentation of the protonated peptides GGG, AAA, and the Lys-rich Polybia-MP1 (IDWKKLLDAAKQIL-NH2). Modeling the microsolvation propensity of protonated n-propylamine [PrNH3]+, a mimic of the Lys side chain and N-terminus, with common gas-phase modifiers (H2O, MeOH, EtOH, iPrOH, acetone, and MeCN) confirms that all solvent molecules form stable clusters at the site of protonation. Moreover, modeling populations of microsolvated clusters indicates that species containing protonated amine moieties exist as microsolvated species with one to six solvent ligands at all effective ion temperatures (Teff) accessible during a DMS experiment (ca. 375-600 K). Calculated Teff of protonated GGG, AAA, and Polybia-MPI using a modified two-temperature theory approach were up to 86 K cooler in DMS environments seeded with solvent vapor compared to pure N2 environments. Stabilizing effects were largely driven by an increase in the ion's apparent collision cross section and by evaporative cooling processes induced by the dynamic evaporation/condensation cycles incurred in the presence of an oscillating electric separation field. When the microsolvating partner was a protic solvent, abstraction of a proton from [MP1 + 3H]3+ to yield [MP1 + 2H]2+ was observed. This result was attributed to the proclivity of protic solvents to form hydrogen-bond networks with enhanced gas-phase basicity. Collectively, microsolvation provides analytes with a solvent "air bag," whereby charge reduction and microsolvation-induced stabilization were shown to shelter peptides from the fragmentation induced by field heating and may play a role in preserving native-like ion configurations.
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Affiliation(s)
- Christian Ieritano
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
| | - Daniel Rickert
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
| | - Joshua Featherstone
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
| | - John F Honek
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
| | - J Larry Campbell
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
- Watermine Innovation, Waterloo N0B 2T0, Ontario, Canada
- Bedrock Scientific, Milton L6T 6J9, Ontario, Canada
| | | | | | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
- Watermine Innovation, Waterloo N0B 2T0, Ontario, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo N2L 3G1, Ontario, Canada
- Centre for Eye and Vision Research, Hong Kong Science Park, New Territories 999077, Hong Kong
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40
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Harper CC, Brauer DD, Francis MB, Williams ER. Direct observation of ion emission from charged aqueous nanodrops: effects on gaseous macromolecular charging. Chem Sci 2021; 12:5185-5195. [PMID: 34168773 PMCID: PMC8179642 DOI: 10.1039/d0sc05707j] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mechanistic information about how gaseous ions are formed from charged droplets has been difficult to establish because direct observation of nanodrops in a size range relevant to gaseous macromolecular ion formation by optical or traditional mass spectrometry methods is challenging owing to their small size and heterogeneity. Here, the mass and charge of individual aqueous nanodrops between 1-10 MDa (15-32 nm diameter) with ∼50-300 charges are dynamically monitored for 1 s using charge detection mass spectrometry. Discrete losses of minimally solvated singly charged ions occur, marking the first direct observation of ion emission from aqueous nanodrops in late stages of droplet evaporation relevant to macromolecular ion formation in native mass spectrometry. Nanodrop charge depends on the identity of constituent ions, with pure water nanodrops charged slightly above the Rayleigh limit and aqueous solutions containing alkali metal ions charged progressively below the Rayleigh limit with increasing cation size. MS2 capsid ions (∼3.5 MDa; ∼27 nm diameter) are more highly charged from aqueous ammonium acetate than from its biochemically preferred, 100 mM NaCl/10 mM Na phosphate solution, consistent with ion emission reducing the nanodrop and resulting capsid charge. The extent of charging indicates that the capsid partially collapses inside the nanodrops prior to the charging and formation of the dehydrated gaseous ions. These results demonstrate that ion emission can affect macromolecular charging and that conformational changes to macromolecular structure can occur in nanodrops prior to the formation of naked gaseous ions.
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Affiliation(s)
- Conner C Harper
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Daniel D Brauer
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Matthew B Francis
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
| | - Evan R Williams
- Department of Chemistry, University of California Berkeley California 94720-1460 USA
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41
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Butler KE, Takinami Y, Rainczuk A, Baker ES, Roberts BR. Utilizing Ion Mobility-Mass Spectrometry to Investigate the Unfolding Pathway of Cu/Zn Superoxide Dismutase. Front Chem 2021; 9:614595. [PMID: 33634076 PMCID: PMC7900566 DOI: 10.3389/fchem.2021.614595] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 01/08/2021] [Indexed: 11/30/2022] Open
Abstract
Native mass spectrometry has emerged as a powerful tool for structural biology as it enables the evaluation of molecules as they occur in their physiological conditions. Ion mobility spectrometry-mass spectrometry (IMS-MS) has shown essential in these analyses as it allows the measurement of the shape of a molecule, denoted as its collision cross section (CCS), and mass. The structural information garnered from native IMS-MS provides insight into the tertiary and quaternary structure of proteins and can be used to validate NMR or crystallographic X-ray structures. Additionally, due to the rapid nature (millisecond measurements) and ability of IMS-MS to analyze heterogeneous solutions, it can be used to address structural questions not possible with traditional structural approaches. Herein, we applied multiple solution conditions to systematically denature bovine Cu/Zn-superoxide dismutase (SOD1) and assess its unfolding pathway from the holo-dimer to the holo-monomer, single-metal monomer, and apo-monomer. Additionally, we compared and noted 1–2% agreement between CCS values from both drift tube IMS and trapped IMS for the SOD1 holo-monomer and holo-dimer. The observed CCS values were in excellent agreement with computational CCS values predicted from the homo-dimer crystal structure, showcasing the ability to use both IMS-MS platforms to provide valuable structural information for molecular modeling of protein interactions and structural assessments.
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Affiliation(s)
- Karen E Butler
- Department of Chemistry, North Carolina State University, Raleigh, NC, United States
| | | | | | - Erin S Baker
- Department of Chemistry, North Carolina State University, Raleigh, NC, United States
| | - Blaine R Roberts
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, United States.,Department of Neuroscience, Emory University School of Medicine, Atlanta, GA, United States
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42
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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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43
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Baker K, Kwok E, Reardon P, Rodriguez DJ, Rolland AD, Wilson JW, Prell JS, Nyarko A. Yorkie-Warts Complexes are an Ensemble of Interconverting Conformers Formed by Multivalent Interactions. J Mol Biol 2020; 433:166776. [PMID: 33383033 DOI: 10.1016/j.jmb.2020.166776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 11/18/2020] [Accepted: 12/16/2020] [Indexed: 11/17/2022]
Abstract
Multiple copies of WW domains and PPXY motif sequences are often reciprocally presented by regulatory proteins that interact at crucial regulatory steps in the cell life cycle. While biophysical studies of single WW domain-single PPXY motif complexes abound in the literature, the molecular mechanisms of multivalent WW domain-PPXY assemblies are still poorly understood. By way of investigating such assemblies, we characterized the multivalent association of the entire cognate binding domains, two WW sequences and five PPXY motifs respectively, of the Yorkie transcription coactivator and the Warts tumor suppressor. Isothermal titration calorimetry, sedimentation velocity, size-exclusion chromatography coupled to multi-angle light scattering and native-state mass spectrometry of Yorkie WW domains interactions with the full-length Warts PPXY domain, and numerous PPXY motif variants of Warts show that the two proteins assemble via binding of tandem WW domains to adjacent PPXY pairs to produce an ensemble of interconverting complexes of variable stoichiometries, binding energetics and WW domain occupancy. Apparently, the Yorkie tandem WW domains first target the two adjacent PPXY motifs at the C-terminus of the Warts polypeptide and additional WW domains bind unoccupied motifs. Similar ensembles of interconverting conformers may be common in multivalent WW domain-PPXY interactions to promote the adaptability and versatility of WW domain-PPXY mediated cellular processes.
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Affiliation(s)
- Kasie Baker
- Department of Biochemistry & Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Ethiene Kwok
- Department of Biochemistry & Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Patrick Reardon
- Department of Biochemistry & Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Diego J Rodriguez
- Department of Biochemistry & Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Amber D Rolland
- Department of Chemistry & Biochemistry, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Jesse W Wilson
- Department of Chemistry & Biochemistry, University of Oregon, Eugene, OR 97403, USA; Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - James S Prell
- Department of Chemistry & Biochemistry, University of Oregon, Eugene, OR 97403, USA; Materials Science Institute, University of Oregon, Eugene, OR 97403, USA
| | - Afua Nyarko
- Department of Biochemistry & Biophysics, Oregon State University, Corvallis, OR 97331, USA.
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44
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Cárdenas R, Martínez-Seoane J, Amero C. Combining Experimental Data and Computational Methods for the Non-Computer Specialist. Molecules 2020; 25:E4783. [PMID: 33081072 PMCID: PMC7594097 DOI: 10.3390/molecules25204783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 01/01/2023] Open
Abstract
Experimental methods are indispensable for the study of the function of biological macromolecules, not just as static structures, but as dynamic systems that change conformation, bind partners, perform reactions, and respond to different stimulus. However, providing a detailed structural interpretation of the results is often a very challenging task. While experimental and computational methods are often considered as two different and separate approaches, the power and utility of combining both is undeniable. The integration of the experimental data with computational techniques can assist and enrich the interpretation, providing new detailed molecular understanding of the systems. Here, we briefly describe the basic principles of how experimental data can be combined with computational methods to obtain insights into the molecular mechanism and expand the interpretation through the generation of detailed models.
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Affiliation(s)
| | | | - Carlos Amero
- Laboratorio de Bioquímica y Resonancia Magnética Nuclear, Centro de Investigaciones Químicas, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos 62209, Mexico; (R.C.); (J.M.-S.)
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45
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Abi-Ghanem J, Rabin C, Porrini M, Rosu F, Gabelica V. Compaction of RNA Hairpins and Their Kissing Complexes in Native Electrospray Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2035-2043. [PMID: 32812759 DOI: 10.1021/jasms.0c00060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
When electrosprayed from typical native MS solution conditions, RNA hairpins and kissing complexes acquire charge states at which they get significantly more compact in the gas phase than their initial structure in solution. Here, we also show the limits of using force field molecular dynamics to interpret the structures of nucleic acid complexes in the gas phase, as the predicted CCS distributions do not fully match the experimental ones. We suggest that higher level calculation levels should be used in the future.
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Affiliation(s)
- Josephine Abi-Ghanem
- Univ Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Bordeaux, France
| | - Clémence Rabin
- Univ Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Bordeaux, France
| | - Massimiliano Porrini
- Univ Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Bordeaux, France
| | - Frédéric Rosu
- Univ Bordeaux, CNRS, INSERM, IECB, UMS 3033, F-33600 Pessac, France
| | - Valérie Gabelica
- Univ Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Bordeaux, France
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46
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Landreh M, Sahin C, Gault J, Sadeghi S, Drum CL, Uzdavinys P, Drew D, Allison TM, Degiacomi MT, Marklund EG. Predicting the Shapes of Protein Complexes through Collision Cross Section Measurements and Database Searches. Anal Chem 2020; 92:12297-12303. [PMID: 32660238 DOI: 10.1021/acs.analchem.0c01940] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In structural biology, collision cross sections (CCSs) from ion mobility mass spectrometry (IM-MS) measurements are routinely compared to computationally or experimentally derived protein structures. Here, we investigate whether CCS data can inform about the shape of a protein in the absence of specific reference structures. Analysis of the proteins in the CCS database shows that protein complexes with low apparent densities are structurally more diverse than those with a high apparent density. Although assigning protein shapes purely on CCS data is not possible, we find that we can distinguish oblate- and prolate-shaped protein complexes by using the CCS, molecular weight, and oligomeric states to mine the Protein Data Bank (PDB) for potentially similar protein structures. Furthermore, comparing the CCS of a ferritin cage to the solution structures in the PDB reveals significant deviations caused by structural collapse in the gas phase. We then apply the strategy to an integral membrane protein by comparing the shapes of a prokaryotic and a eukaryotic sodium/proton antiporter homologue. We conclude that mining the PDB with IM-MS data is a time-effective way to derive low-resolution structural models.
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Affiliation(s)
- Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, 171 65, Stockholm, Sweden
| | - Cagla Sahin
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, 171 65, Stockholm, Sweden.,Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark
| | - Joseph Gault
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Samira Sadeghi
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 119228, Singapore
| | - Chester L Drum
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Dr, Singapore 119228, Singapore
| | - Povilas Uzdavinys
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 114 19, Sweden
| | - David Drew
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 114 19, Sweden
| | - Timothy M Allison
- Biomolecular Interaction Centre and School of Physical and Chemical Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
| | - Matteo T Degiacomi
- Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Erik G Marklund
- Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala 751 23, Sweden
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47
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Miller ZM, Zhang JD, Donald WA, Prell JS. Gas-Phase Protonation Thermodynamics of Biological Lipids: Experiment, Theory, and Implications. Anal Chem 2020; 92:10365-10374. [PMID: 32628014 DOI: 10.1021/acs.analchem.0c00613] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Phospholipids are important to cellular function and are a vital structural component of plasma and organelle membranes. These membranes isolate the cell from its environment, allow regulation of the internal concentrations of ions and small molecules, and host diverse types of membrane proteins. It remains extremely challenging to identify specific membrane protein-lipid interactions and their relative strengths. Native mass spectrometry, an intrinsically gas-phase method, has recently been demonstrated as a promising tool for identifying endogenous protein-lipid interactions. However, to what extent the identified interactions reflect solution- versus gas-phase binding strengths is not known. Here, the "Extended" Kinetic Method and ab initio computations at three different levels of theory are used to experimentally and theoretically determine intrinsic gas-phase basicities (GB, ΔG for deprotonation of the protonated base) and proton affinities (PA, ΔH for deprotonation of the protonated base) of six lipids representing common phospholipid types. Gas-phase acidities (ΔG and ΔH for deprotonation) of neutral phospholipids are also evaluated computationally and ranked experimentally. Intriguingly, it is found that two of these phospholipids, sphingomyelin and phosphatidylcholine, have the highest GB of any small, monomeric biomolecules measured to date and are more basic than arginine. Phosphatidylethanolamine and phosphatidylserine are found to be similar in GB to basic amino acids lysine and histidine, and phosphatidic acid and phosphatidylglycerol are the least basic of the six lipid types studied, though still more basic than alanine. Kinetic Method experiments and theory show that the gas-phase acidities of these phospholipids are high but less extreme than their GB values, with phosphatidylserine and phosphatidylglycerol being the most acidic. These results indicate that sphingomyelin and phosphatidylcholine lipids can act as charge-reducing agents when dissociated from native membrane protein-lipid complexes in the gas phase and provide a straightforward model to explain the results of several recent native mass spectrometry studies of protein-lipid complexes.
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Affiliation(s)
- Zachary M Miller
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States
| | - J Diana Zhang
- School of Chemistry, University of New South Wales, Sydney, New South Wales, Australia, 2052
| | - W Alexander Donald
- School of Chemistry, University of New South Wales, Sydney, New South Wales, Australia, 2052
| | - James S Prell
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, Oregon 97403-1253, United States.,Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1252, United States
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48
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Allison TM, Barran P, Cianférani S, Degiacomi MT, Gabelica V, Grandori R, Marklund EG, Menneteau T, Migas LG, Politis A, Sharon M, Sobott F, Thalassinos K, Benesch JLP. Computational Strategies and Challenges for Using Native Ion Mobility Mass Spectrometry in Biophysics and Structural Biology. Anal Chem 2020; 92:10872-10880. [DOI: 10.1021/acs.analchem.9b05791] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Timothy M. Allison
- School of Physical and Chemical Sciences, Biomolecular Interaction Centre, University of Canterbury, Christchurch 8140, New Zealand
| | - Perdita Barran
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
| | - Matteo T. Degiacomi
- Department of Physics, Durham University, South Road, Durham, DH1 3LE, United Kingdom
| | - Valérie Gabelica
- University of Bordeaux, INSERM and CNRS, ARNA Laboratory, IECB site, 2 Rue Robert Escarpit, 33600 Pessac, France
| | - Rita Grandori
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126, Milan, Italy
| | - Erik G. Marklund
- Department of Chemistry - BMC, Uppsala University, Box 576, 75123, Uppsala, Sweden
| | - Thomas Menneteau
- Division of Biosciences, Institute of Structural and Molecular Biology, University College of London, Gower Street, London WC1E 6BT, United Kingdom
| | - Lukasz G. Migas
- Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Argyris Politis
- Department of Chemistry, King’s College London, 7 Trinity Street, London SE1 1DB, United Kingdom
| | - Michal Sharon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Frank Sobott
- Biomolecular & Analytical Mass Spectrometry, Department of Chemistry, University of Antwerp, 2020 Antwerp, Belgium
- School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Konstantinos Thalassinos
- Department of Chemistry, King’s College London, 7 Trinity Street, London SE1 1DB, United Kingdom
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, Malet Street, London WC1E 7HX, United Kingdom
| | - Justin L. P. Benesch
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, South Parks Road, Oxford OX1 3TA, United Kingdom
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49
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Wilson JW, Donor MT, Shepherd SO, Prell JS. Increasing Collisional Activation of Protein Complexes Using Smaller Aperture Source Sampling Cones on a Synapt Q-IM-TOF Instrument with a Stepwave Source. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:10.1021/jasms.0c00117. [PMID: 32628844 PMCID: PMC7855748 DOI: 10.1021/jasms.0c00117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Quadrupole ion mobility time-of-flight (Q-IM-TOF) mass spectrometers have revolutionized investigation of native biomolecular complexes. High pressures in the sources of these instruments aid transmission of protein complexes through damping of kinetic energy by collisional cooling. As adducts are removed through collisional heating (declustering), excessive collisional cooling can prevent removal of nonspecific adducts from protein ions, leading to inaccurate mass measurements, broad mass spectral peaks, and obfuscation of ligand binding. We show that reducing the source pressure using smaller aperture source sampling cones (SC) in a Waters Synapt G2-Si instrument increases protein ion heating by decreasing collisional cooling, providing a simple way to enhance removal of adducted salts from soluble proteins (GroEL 14-mer) and detergents from a transmembrane protein complex (heptameric Staphylococcus aureus α-hemolysin, αHL). These experiments are supported by ion heating and cooling simulations which demonstrate reduced collisional cooling at lower source pressures. Using these easily swapped sample cones of different apertures is a facile approach to reproducibly extend the range of activation in Synapt-type instruments.
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Affiliation(s)
- Jesse W. Wilson
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon Eugene, OR, USA, 97403-1253
| | - Micah T. Donor
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon Eugene, OR, USA, 97403-1253
| | - Samantha O. Shepherd
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon Eugene, OR, USA, 97403-1253
| | - James S. Prell
- Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon Eugene, OR, USA, 97403-1253
- Materials Science Institute, University of Oregon, 1252 University of Oregon, OR, USA, 97403-1252
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Sever AIM, Konermann L. Gas Phase Protein Folding Triggered by Proton Stripping Generates Inside-Out Structures: A Molecular Dynamics Simulation Study. J Phys Chem B 2020; 124:3667-3677. [DOI: 10.1021/acs.jpcb.0c01934] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Alexander I. M. Sever
- 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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