1
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Moore CC, Staroverov VN, Konermann L. Using Density Functional Theory for Testing the Robustness of Mobile-Proton Molecular Dynamics Simulations on Electrosprayed Ions: Structural Implications for Gaseous Proteins. J Phys Chem B 2023; 127:4061-4071. [PMID: 37116098 DOI: 10.1021/acs.jpcb.3c01581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Current experiments only provide low-resolution information on gaseous protein ions generated by electrospray ionization (ESI). Molecular dynamics (MD) simulations can yield complementary insights. Unfortunately, conventional MD does not capture the mobile nature of protons in gaseous proteins. Mobile-proton MD (MPMD) overcomes this limitation. Earlier MPMD data at 300 K indicated that protein ions generated by "native" ESI retain solution-like structures with a hydrophobic core and zwitterionic exterior [Bakhtiari, M.; Konermann, L. J. Phys. Chem. B 2019, 123, 1784-1796]. MPMD redistributes protons using electrostatic and proton affinity calculations. The robustness of this approach has never been scrutinized. Here, we close this gap by benchmarking MPMD against density functional theory (DFT) at the B3LYP/6-31G* level, which is well suited for predicting proton affinities. The computational cost of DFT necessitated the use of small peptides. The MPMD energetic ranking of proton configurations was found to be consistent with DFT single-point energies, implying that MPMD can reliably identify favorable protonation sites. Peptide MPMD runs converged to DFT-optimized structures only when applying 300-500 K temperature cycling, which was necessary to prevent trapping in local minima. Temperature cycling MPMD was then applied to gaseous protein ions. Native ubiquitin converted to slightly expanded structures with a zwitterionic core and a nonpolar exterior. Our data suggest that such inside-out protein structures are intrinsically preferred in the gas phase, and that they form in ESI experiments after moderate collisional excitation. This is in contrast to native ESI (with minimal collisional excitation, simulated by MPMD at 300 K), where kinetic trapping promotes the survival of solution-like structures. In summary, this work validates the MPMD approach for simulations on gaseous peptides and proteins.
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Affiliation(s)
- Conrad C Moore
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Viktor N Staroverov
- 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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2
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Raznikov V, Raznikova M, Sulimenkov I, Zelenov V. Separation of mass spectra of hydrogen-deuterium exchanged ions obtained by electrospray of solutions of biopolymers with unknown primary structure. Anal Bioanal Chem 2023; 415:2193-2207. [PMID: 36943444 DOI: 10.1007/s00216-023-04625-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 02/21/2023] [Indexed: 03/23/2023]
Abstract
The work is dedicated to further development of our described method for analyzing mass spectra of biomolecules acquired as a result of hydrogen-deuterium exchange reactions (HDXs). The modified method consists of separating HDX distributions via their approximations by a minimum number of components corresponding to independent H/D substitutions and independent charge carrier retentions in different spatial isoforms or conformations of biomolecules with unknown primary structures. In this case, neither the natural isotopic distribution nor the exact number of active sites involved in HDXs and H+ or D+ attachments can be determined in advance. Original H/D electrospray mass spectra of an apamin solution were taken from our previous work. In that work, taking into account the natural isotopic distribution of apamin molecules, three main conformations of apamin ions were found as a result of separating the H/D mass spectra of the apamin solution for the gas flow with the addition of about 10% ND3 molecules. Using the proposed modified method that does not require knowledge of the primary structure of the biomolecules gave similar results with slight deviations of calculated HDX distributions of the apamin ions from those obtained earlier. The maximum difference between mean values of the calculated HDX distributions for ions of the same charge in both cases does not exceed a few percent. In addition, HDX mass spectra of the apamin complex with an adduct of unknown structure were processed. Such analysis gave also three main fractions of ions with relatively large contributions when ND3 was injected into a radio-frequency quadrupole. In the absence of ND3 flow, the results of calculations for apamin and its complex were close to each other too. The formation of the apamin complex most probably in solution was confirmed by performed calculations.
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Affiliation(s)
- Valery Raznikov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow, 142432, Russia.
| | - Marina Raznikova
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow, 142432, Russia.
| | - Ilia Sulimenkov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow, 142432, Russia
| | - Vladislav Zelenov
- Chernogolovka Branch of the N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow, 142432, Russia
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3
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Chaturvedi R, Webb IK. Multiplexed Conformationally Selective, Localized Gas-Phase Hydrogen Deuterium Exchange of Protein Ions Enabled by Transmission-Mode Electron Capture Dissociation. Anal Chem 2022; 94:8975-8982. [PMID: 35708487 DOI: 10.1021/acs.analchem.2c00942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this article, we present an approach for conformationally multiplexed, localized hydrogen deuterium exchange (HDX) of gas-phase protein ions facilitated by ion mobility (IM) followed by electron capture dissociation (ECD). A quadrupole-IM-time of flight instrument previously modified to enable ECD in transmission mode (without ion trapping) immediately following a mobility separation was further modified to allow for deuterated ammonia (ND3) to be leaked in after m/z selection. Collisional activation was minimized to prevent deuterium scrambling from giving structurally irrelevant results. Gas-phase HDX with ECD fragmentation for exchange site localization was demonstrated with the extensively studied protein folding models ubiquitin and cytochrome c. Ubiquitin was ionized from conditions that stabilize the native state and conditions that stabilize the partially folded A-state. IM of deuterated ubiquitin 6+ ions allowed the separation of more compact conformers from more extended conformers. ECD of the separated subpopulations revealed that the more extended (later arriving) conformers had significant, localized differences in the amount of HDX observed. The 5+ charge state showed many regions with protection from HDX, and the 11+ charge state, ionized from conditions that stabilize the A-state, showed high levels of deuterium incorporation throughout most of the protein sequence. The 7+ ions of cytochrome c ionized from aqueous conditions showed greater HDX with unstructured regions of the protein relative to interior, structured regions, especially those involved in heme binding. With careful tuning and attention to deuterium scrambling, our approach holds promise for determining region-specific information on a conformer-selected basis for gas-phase protein structures, including localized characterizations of ligand, epitope, and protein-protein binding.
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Affiliation(s)
- Ritu Chaturvedi
- 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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4
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Tran MH, Schoeder CT, Schey KL, Meiler J. Computational Structure Prediction for Antibody-Antigen Complexes From Hydrogen-Deuterium Exchange Mass Spectrometry: Challenges and Outlook. Front Immunol 2022; 13:859964. [PMID: 35720345 PMCID: PMC9204306 DOI: 10.3389/fimmu.2022.859964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 04/22/2022] [Indexed: 11/21/2022] Open
Abstract
Although computational structure prediction has had great successes in recent years, it regularly fails to predict the interactions of large protein complexes with residue-level accuracy, or even the correct orientation of the protein partners. The performance of computational docking can be notably enhanced by incorporating experimental data from structural biology techniques. A rapid method to probe protein-protein interactions is hydrogen-deuterium exchange mass spectrometry (HDX-MS). HDX-MS has been increasingly used for epitope-mapping of antibodies (Abs) to their respective antigens (Ags) in the past few years. In this paper, we review the current state of HDX-MS in studying protein interactions, specifically Ab-Ag interactions, and how it has been used to inform computational structure prediction calculations. Particularly, we address the limitations of HDX-MS in epitope mapping and techniques and protocols applied to overcome these barriers. Furthermore, we explore computational methods that leverage HDX-MS to aid structure prediction, including the computational simulation of HDX-MS data and the combination of HDX-MS and protein docking. We point out challenges in interpreting and incorporating HDX-MS data into Ab-Ag complex docking and highlight the opportunities they provide to build towards a more optimized hybrid method, allowing for more reliable, high throughput epitope identification.
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Affiliation(s)
- Minh H. Tran
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, United States
- Center of Structural Biology, Vanderbilt University, Nashville, TN, United States
- Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Clara T. Schoeder
- Center of Structural Biology, Vanderbilt University, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Institute for Drug Discovery, University Leipzig Medical School, Leipzig, Germany
| | - Kevin L. Schey
- Mass Spectrometry Research Center, Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Jens Meiler
- Center of Structural Biology, Vanderbilt University, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Institute for Drug Discovery, University Leipzig Medical School, Leipzig, Germany
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5
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Kaltashov IA, Bobst CE, Pawlowski J, Wang G. Mass spectrometry-based methods in characterization of the higher order structure of protein therapeutics. J Pharm Biomed Anal 2020; 184:113169. [PMID: 32092629 DOI: 10.1016/j.jpba.2020.113169] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/06/2020] [Accepted: 02/11/2020] [Indexed: 12/31/2022]
Abstract
Higher order structure of protein therapeutics is an important quality attribute, which dictates both potency and safety. While modern experimental biophysics offers an impressive arsenal of state-of-the-art tools that can be used for the characterization of higher order structure, many of them are poorly suited for the characterization of biopharmaceutical products. As a result, these analyses were traditionally carried out using classical techniques that provide relatively low information content. Over the past decade, mass spectrometry made a dramatic debut in this field, enabling the characterization of higher order structure of biopharmaceuticals as complex as monoclonal antibodies at a level of detail that was previously unattainable. At present, mass spectrometry is an integral part of the analytical toolbox across the industry, which is critical not only for quality control efforts, but also for discovery and development.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA.
| | - Cedric E Bobst
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Jake Pawlowski
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Guanbo Wang
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu Province, PR China
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6
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Kostyukevich Y, Acter T, Zherebker A, Ahmed A, Kim S, Nikolaev E. Hydrogen/deuterium exchange in mass spectrometry. MASS SPECTROMETRY REVIEWS 2018; 37:811-853. [PMID: 29603316 DOI: 10.1002/mas.21565] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 02/22/2018] [Accepted: 03/08/2018] [Indexed: 05/22/2023]
Abstract
The isotopic exchange approach is in use since the first observation of such reactions in 1933 by Lewis. This approach allows the investigation of the pathways of chemical and biochemical reactions, determination of structure, composition, and conformation of molecules. Mass spectrometry has now become one of the most important analytical tools for the monitoring of the isotopic exchange reactions. Investigation of conformational dynamics of proteins, quantitative measurements, obtaining chemical, and structural information about individual compounds of the complex natural mixtures are mainly based on the use of isotope exchange in combination with high resolution mass spectrometry. The most important reaction is the Hydrogen/Deuterium exchange, which is mainly performed in the solution. Recently we have developed the approach allowing performing of the Hydrogen/Deuterium reaction on-line directly in the ionization source under atmospheric pressure. Such approach simplifies the sample preparation and can accelerate the exchange reaction so that certain hydrogens that are considered as non-labile will also participate in the exchange. The use of in-ionization source H/D exchange in modern mass spectrometry for structural elucidation of molecules serves as the basic theme in this review. We will focus on the mechanisms of the isotopic exchange reactions and on the application of in-ESI, in-APCI, and in-APPI source Hydrogen/Deuterium exchange for the investigation of petroleum, natural organic matter, oligosaccharides, and proteins including protein-protein complexes. The simple scenario for adaptation of H/D exchange reactions into mass spectrometric method is also highlighted along with a couple of examples collected from previous studies.
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Affiliation(s)
- Yury Kostyukevich
- Skolkovo Institute of Science and Technology, Skolkovo, Russian Federation
- Institute for Energy Problems of Chemical Physics Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudnyi, Moscow Region, Russia
| | - Thamina Acter
- Department of Chemistry, Kyungpook National University, Daegu, Republic of Korea
| | - Alexander Zherebker
- Skolkovo Institute of Science and Technology, Skolkovo, Russian Federation
- Institute for Energy Problems of Chemical Physics Russian Academy of Sciences, Moscow, Russia
| | - Arif Ahmed
- Department of Chemistry, Kyungpook National University, Daegu, Republic of Korea
| | - Sunghwan Kim
- Department of Chemistry, Kyungpook National University, Daegu, Republic of Korea
- Green Nano Center, Kyungpook National University, Daegu, Republic of Korea
| | - Eugene Nikolaev
- Skolkovo Institute of Science and Technology, Skolkovo, Russian Federation
- Institute for Energy Problems of Chemical Physics Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudnyi, Moscow Region, Russia
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7
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Kostyukevich Y, Shulga AA, Kononikhin A, Popov I, Nikolaev E, Deyev S. CID fragmentation, H/D exchange and supermetallization of Barnase-Barstar complex. Sci Rep 2017; 7:6176. [PMID: 28733680 PMCID: PMC5522418 DOI: 10.1038/s41598-017-06507-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 06/13/2017] [Indexed: 01/02/2023] Open
Abstract
The barnase-barstar complex is one of the most stable protein-protein complexes and has a very wide range of possible applications. Here we report the use of top-down mass spectrometry for the investigation of the structure of this complex, its ionization via ESI, isolation and fragmentation. It was found that the asymmetry of the resulting charge state distributions of the protein monomer product ions increased as the charge state of the precursor ions increased. For the investigation of the 3D structure of the complex, the gas phase H/D exchange reaction was used. In addition, supermetallized ions of the complex with Zn were produced and investigated. It was observed that an increase in the number of metals bound to the complex results in a change in complex stability and the charge distribution between protein fragment. Analysis of the fragmentation pattern of the supermetallized complex [bn-b* + 5Zn]10+ indicated that this ion is present in different conformations with different charges and Zn distributions. Since Zn cannot migrate, such structures must be formed during ionization.
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Affiliation(s)
- Yury Kostyukevich
- Skolkovo Institute of Science and Technology Novaya St., 100, Skolkovo, 143025, Russian Federation.,Institute for Energy Problems of Chemical Physics, Russian Academy of Sciences, Leninskij pr. 38, k.2, 119334, Moscow, Russia.,Emanuel Institute for Biochemical Physics, Russian Academy of Sciences Kosygina st. 4, 119334, Moscow, Russia.,Moscow Institute of Physics and Technology, 141700, Dolgoprudnyi, Moscow Region, Russia
| | - Aleksej A Shulga
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10, Miklukho-Maklaya str., Moscow, 117997, Russian Federation
| | - Alexey Kononikhin
- Institute for Energy Problems of Chemical Physics, Russian Academy of Sciences, Leninskij pr. 38, k.2, 119334, Moscow, Russia.,Moscow Institute of Physics and Technology, 141700, Dolgoprudnyi, Moscow Region, Russia
| | - Igor Popov
- Emanuel Institute for Biochemical Physics, Russian Academy of Sciences Kosygina st. 4, 119334, Moscow, Russia.,Moscow Institute of Physics and Technology, 141700, Dolgoprudnyi, Moscow Region, Russia
| | - Eugene Nikolaev
- Skolkovo Institute of Science and Technology Novaya St., 100, Skolkovo, 143025, Russian Federation. .,Institute for Energy Problems of Chemical Physics, Russian Academy of Sciences, Leninskij pr. 38, k.2, 119334, Moscow, Russia. .,Emanuel Institute for Biochemical Physics, Russian Academy of Sciences Kosygina st. 4, 119334, Moscow, Russia. .,Moscow Institute of Physics and Technology, 141700, Dolgoprudnyi, Moscow Region, Russia.
| | - Sergey Deyev
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 16/10, Miklukho-Maklaya str., Moscow, 117997, Russian Federation.,National Research Tomsk Polytechnic University, 30, av. Lenina, Tomsk, 634050, Russia
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8
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Gessner C, Steinchen W, Bédard S, J Skinner J, Woods VL, Walsh TJ, Bange G, Pantazatos DP. Computational method allowing Hydrogen-Deuterium Exchange Mass Spectrometry at single amide Resolution. Sci Rep 2017. [PMID: 28630467 PMCID: PMC5476592 DOI: 10.1038/s41598-017-03922-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Hydrogen-deuterium exchange (HDX) coupled with mass spectrometry (HDXMS) is a rapid and effective method for localizing and determining protein stability and dynamics. Localization is routinely limited to a peptide resolution of 5 to 20 amino acid residues. HDXMS data can contain information beyond that needed for defining protein stability at single amide resolution. Here we present a method for extracting this information from an HDX dataset to generate a HDXMS protein stability fingerprint. High resolution (HR)-HDXMS was applied to the analysis of a model protein of a spectrin tandem repeat that exemplified an intuitive stability profile based on the linkage of two triple helical repeats connected by a helical linker. The fingerprint recapitulated expected stability maximums and minimums with interesting structural features that corroborate proposed mechanisms of spectrin flexibility and elasticity. HR-HDXMS provides the unprecedented ability to accurately assess protein stability at the resolution of a single amino acid. The determination of HDX stability fingerprints may be broadly applicable in many applications for understanding protein structure and function as well as protein ligand interactions.
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Affiliation(s)
- Chris Gessner
- Indiana University, Department of Informatics and Computing, Bloomington, IN, USA
| | - Wieland Steinchen
- Philipps-University Marburg, Faculty of Chemistry & LOEWE Center for Synthetic Microbiology Hans-Meerwein-Strasse, 35043, Marburg, Germany
| | - Sabrina Bédard
- GlaxoSmithKline, Platform Technology & Science, Collegeville Road, Collegeville, Pennsylvania, 19426, United States
| | - John J Skinner
- iHuman Institute, ShanghaiTech University, 99 Haike Road, Pudong, Shanghai, China
| | - Virgil L Woods
- Indiana University, Department of Informatics and Computing, Bloomington, IN, USA
| | - Thomas J Walsh
- Weill Cornell Medicine, Transplantation-Oncology Infectious Disease Program, Division of Infectious Diseases, 1300 York Ave, New York, NY, 10065, USA
| | - Gert Bange
- Philipps-University Marburg, Faculty of Chemistry & LOEWE Center for Synthetic Microbiology Hans-Meerwein-Strasse, 35043, Marburg, Germany
| | - Dionysios P Pantazatos
- Weill Cornell Medicine, Transplantation-Oncology Infectious Disease Program, Division of Infectious Diseases, 1300 York Ave, New York, NY, 10065, USA.
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9
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Kostyukevich Y, Kononikhin A, Popov I, Nikolaev E. Conformational changes of ubiquitin during electrospray ionization as determined by in-ESI source H/D exchange combined with high-resolution MS and ECD fragmentation. JOURNAL OF MASS SPECTROMETRY : JMS 2014; 49:989-94. [PMID: 25303388 DOI: 10.1002/jms.3409] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 05/26/2014] [Accepted: 06/06/2014] [Indexed: 05/19/2023]
Abstract
In the paper, we have demonstrated the possibility of performing hydrogen/deuterium (H/D) exchange of proteins in the region of gas-phase ion formation in an electrospray ion source by saturating the electrospray ionization source with vapors of a deuterating agent (D(2)O or MeOD). In this region, charged droplets are shrinking and the protein ions transfer into the gas phase. As a model protein, we have used ubiquitin whose ion mobility spectrometry and gas-phase H/D exchange in the vacuum part of a mass spectrometer demonstrated the presence of gas-phase conformers with different cross sections and H/D exchange rates. In our experiments, we observed monomodal deuterium distributions for all solvents, charge states, desolvating capillary temperature and types of deuterating agent. Also, we found that the number of H/D exchanges increases with an increasing desolvating capillary temperature and decreasing charge state. We observed that solution composition (49 : 50 : 1 H(2)O : MeOH : formic acid or 99 : 1 H(2)O : formic acid) influences the charge-state distribution but did not change the degree of H/D exchange for the same charge state. Electron-capture dissociation fragmentation shows that higher charge states contain a segment that is protected from access by the deuterating agent.
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Affiliation(s)
- Yury Kostyukevich
- Russian Academy of Sciences, Institute for Energy Problems of Chemical Physics, Leninskij pr. 38 k.2, 119334, Moscow, Russia; Moscow Institute of Physics and Technology, 141700, Dolgoprudnyi, Moscow Region, Russia
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10
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Wang G, Kaltashov IA. Approach to characterization of the higher order structure of disulfide-containing proteins using hydrogen/deuterium exchange and top-down mass spectrometry. Anal Chem 2014; 86:7293-8. [PMID: 24988145 PMCID: PMC4144750 DOI: 10.1021/ac501789e] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
![]()
Top-down hydrogen/deuterium exchange
(HDX) with mass spectrometric
(MS) detection has recently matured to become a potent biophysical
tool capable of providing valuable information on higher order structure
and conformational dynamics of proteins at an unprecedented level
of structural detail. However, the scope of the proteins amenable
to the analysis by top-down HDX MS still remains limited, with the
protein size and the presence of disulfide bonds being the two most
important limiting factors. While the limitations imposed by the physical
size of the proteins gradually become more relaxed as the sensitivity,
resolution and dynamic range of modern MS instrumentation continue
to improve at an ever accelerating pace, the presence of the disulfide
linkages remains a much less forgiving limitation even for the proteins
of relatively modest size. To circumvent this problem, we introduce
an online chemical reduction step following completion and quenching
of the HDX reactions and prior to the top-down MS measurements of
deuterium occupancy of individual backbone amides. Application of
the new methodology to the top-down HDX MS characterization of a small
(99 residue long) disulfide-containing protein β2-microglobulin allowed the backbone amide protection to be probed
with nearly a single-residue resolution across the entire sequence.
The high-resolution backbone protection pattern deduced from the top-down
HDX MS measurements carried out under native conditions is in excellent
agreement with the crystal structure of the protein and high-resolution
NMR data, suggesting that introduction of the chemical reduction step
to the top-down routine does not trigger hydrogen scrambling either
during the electrospray ionization process or in the gas phase prior
to the protein ion dissociation.
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Affiliation(s)
- Guanbo Wang
- Department of Chemistry, University of Massachusetts-Amherst , 710 North Pleasant Street, LGRT 104, Amherst, Massachusetts 01003 United States
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11
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Conformer-specific characterization of nonnative protein states using hydrogen exchange and top-down mass spectrometry. Proc Natl Acad Sci U S A 2013; 110:20087-92. [PMID: 24277803 DOI: 10.1073/pnas.1315029110] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Characterization of structure and dynamics of nonnative protein states is important for understanding molecular mechanisms of processes as diverse as folding, binding, aggregation, and enzyme catalysis to name just a few; however, selectively probing local minima within rugged energy landscapes remains a problem. Mass spectrometry (MS) coupled with hydrogen/deuterium exchange (HDX) offers a unique advantage of being able to make a distinction among multiple protein conformers that coexist in solution; however, detailed structural interrogation of such states previously remained out of reach of HDX MS. In this work, we exploited the aforementioned unique feature of HDX MS in combination with the ability of MS to isolate narrow populations of protein ions to characterize individual protein conformers coexisting in solution in equilibrium. Subsequent fragmentation of the protein ions using electron-capture dissociation allowed us to allocate the deuterium distribution along the protein backbone, yielding a backbone-amide protection map for the selected conformer unaffected by contributions from other protein states present in solution. The method was tested with the small regulatory protein ubiquitin (Ub), which is known to form nonnative intermediate states under a variety of mildly denaturing conditions. Protection maps of these intermediate states obtained at residue-level resolution provide clear evidence that they are very similar to the so-called A-state of Ub that is formed in solutions with low pH and high alcohol. Method validation was carried out by comparing the backbone-amide protection map of native Ub with those deduced from high-resolution NMR measurements.
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12
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Abzalimov RR, Bobst CE, Kaltashov IA. A new approach to measuring protein backbone protection with high spatial resolution using H/D exchange and electron capture dissociation. Anal Chem 2013; 85:9173-80. [PMID: 23978257 DOI: 10.1021/ac401868b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Inadequate spatial resolution remains one of the most serious limitations of hydrogen/deuterium exchange-mass spectrometry (HDX-MS), especially when applied to larger proteins (over 30 kDa). Supplementing proteolytic fragmentation of the protein in solution with ion dissociation in the gas phase has been used successfully by several groups to obtain near-residue level resolution. However, the restrictions imposed by the LC-MS/MS mode of operation on the data acquisition time frame makes it difficult in many cases to obtain a signal-to-noise ratio adequate for reliable assignment of the backbone amide protection levels at individual residues. This restriction is lifted in the present work by eliminating the LC separation step from the workflow and taking advantage of the high resolving power and dynamic range of a Fourier transform ion cyclotron resonance-mass spectrometer (FTICR-MS). A residue-level resolution is demonstrated for a peptic fragment of a 37 kDa recombinant protein (N-lobe of human serum transferrin), using electron-capture dissociation as an ion fragmentation tool. The absence of hydrogen scrambling in the gas phase prior to ion dissociation is verified using redundant HDX-MS data generated by FTICR-MS. The backbone protection pattern generated by direct HDX-MS/MS is in excellent agreement with the known crystal structure of the protein but also provides information on conformational dynamics, which is not available from the static X-ray structure.
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Affiliation(s)
- Rinat R Abzalimov
- Department of Chemistry, University of Massachusetts-Amherst , Amherst, MA 01003, United States
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13
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Kaltashov IA, Bobst CE, Abzalimov RR. Mass spectrometry-based methods to study protein architecture and dynamics. Protein Sci 2013; 22:530-44. [PMID: 23436701 DOI: 10.1002/pro.2238] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 02/11/2013] [Accepted: 02/13/2013] [Indexed: 11/09/2022]
Abstract
Mass spectrometry is now an indispensable tool in the armamentarium of molecular biophysics, where it is used for tasks ranging from protein sequencing and mapping of post-translational modifications to studies of higher order structure, conformational dynamics, and interactions of proteins with small molecule ligands and other biopolymers. This mini-review highlights several popular mass spectrometry-based tools that are now commonly used for structural studies of proteins beyond their covalent structure with a particular emphasis on hydrogen exchange and direct electrospray ionization mass spectrometry.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts, USA.
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Liu Y, Yin Q, Yuan Y, Yang W, Jiang C, Huang C. Infectomics Screening for Novel Antiviral Drug Targets. Drug Dev Res 2012. [PMCID: PMC7163650 DOI: 10.1002/ddr.21027] [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] [Indexed: 02/05/2023]
Abstract
Copyright 2012 Wiley-Liss, Inc., A Wiley Company Infectomics, a novel way to globally and comprehensively understand the interactions between microbial pathogens and their hosts, has significantly expanded understanding of the microbial infections. The infectomics view of viral–host interactions on the viral perspective principally focuses on gene acquisition, deletion, and point mutation, while traditional antiviral drug discovery concentrates on viral encoding proteins. Recently, high‐throughput technologies, such as mass spectrometry‐based proteomics, activity‐based protein profiling, microarray analysis, yeast two‐hybrid assay, small interfering RNA screening, and micro RNA profiling, have been gradually employed in the research of virus–host interactions. Besides, signaling pathways and cellular processes involved in viral–host interactions provide new insights of infectomics in antiviral drug discovery. In this review, we summarize related infectomics approaches in the studies of virus–host interactions, which shed light on the development of novel antiviral drug targets screening.
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Affiliation(s)
- Yuan Liu
- The State Key Laboratory of Biotherapy; West China Hospital, West China, Sichuan University; Chengdu; 610041; China
| | - Qi Yin
- The State Key Laboratory of Biotherapy; West China Hospital, West China, Sichuan University; Chengdu; 610041; China
| | - Yao Yuan
- The State Key Laboratory of Biotherapy; West China Hospital, West China, Sichuan University; Chengdu; 610041; China
| | - Wenyong Yang
- The State Key Laboratory of Biotherapy; West China Hospital, West China, Sichuan University; Chengdu; 610041; China
| | - Chuangui Jiang
- The State Key Laboratory of Biotherapy; West China Hospital, West China, Sichuan University; Chengdu; 610041; China
| | - Canhua Huang
- The State Key Laboratory of Biotherapy; West China Hospital, West China, Sichuan University; Chengdu; 610041; China
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15
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Brock A. Fragmentation hydrogen exchange mass spectrometry: A review of methodology and applications. Protein Expr Purif 2012; 84:19-37. [DOI: 10.1016/j.pep.2012.04.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 04/13/2012] [Indexed: 01/19/2023]
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16
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Pan J, Han J, Borchers CH, Konermann L. Characterizing short-lived protein folding intermediates by top-down hydrogen exchange mass spectrometry. Anal Chem 2011; 82:8591-7. [PMID: 20849085 DOI: 10.1021/ac101679j] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
This work combines pulsed hydrogen/deuterium exchange (HDX) and top-down mass spectrometry for the structural characterization of short-lived protein folding intermediates. A custom-built flow device with three sequential mixing steps is used for (i) triggering protein folding, (ii) pulsed D(2)O labeling, and (iii) acid quenching. The earliest folding time point that can be studied with this system is 10 ms. The mixing device was coupled online to the electrospray source of a Fourier transform mass spectrometer, where intact protein ions are fragmented by electron capture dissociation (ECD). The viability of this experimental strategy is demonstrated by applying it to the refolding of horse apo-myoglobin (aMb), a reaction known to involve a transient intermediate. Cooling of the mixing device to 0 °C reduces the reaction rate such that the folding process occurs within the experimentally accessible time window. Top-down ECD provides an average spatial resolution of ca. 2 residues, surpassing the resolution typically achieved in traditional proteolytic digestion/HDX studies. Amide back exchange is virtually eliminated by the short (∼1 s) duration of the acid quenching step. The aMb folding intermediate exhibits HDX protection in helices G and H, whereas the remainder of the protein is largely unfolded. Marginal protection is seen for helix A. Overall, the top-down ECD approach used here offers insights into the sequence of events leading from the unfolded state to the native conformation, with envisioned future applications in the areas of protein misfolding and aggregation. The time-resolved experiments reported herein represent an extension of our previous work, where HDX/MS with top-down ECD was employed for monitoring "static" protein structures under equilibrium conditions (Pan et al. J. Am. Chem. Soc. 2009, 131, 12801).
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Affiliation(s)
- Jingxi Pan
- Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7, Canada
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Carlton DD, Schug KA. A review on the interrogation of peptide–metal interactions using electrospray ionization-mass spectrometry. Anal Chim Acta 2011; 686:19-39. [DOI: 10.1016/j.aca.2010.11.050] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 11/24/2010] [Accepted: 11/25/2010] [Indexed: 11/27/2022]
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Pan Y, Konermann L. Membrane protein structural insights from chemical labeling and mass spectrometry. Analyst 2010; 135:1191-200. [DOI: 10.1039/b924805f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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