1
|
Chen X, Roeters SJ, Cavanna F, Alvarado J, Baiz CR. Crowding alters F-actin secondary structure and hydration. Commun Biol 2023; 6:900. [PMID: 37660224 PMCID: PMC10475093 DOI: 10.1038/s42003-023-05274-3] [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: 04/28/2023] [Accepted: 08/22/2023] [Indexed: 09/04/2023] Open
Abstract
Actin, an important component of eukaryotic cell cytoskeleton, regulates cell shape and transport. The morphology and biochemical properties of actin filaments are determined by their structure and protein-protein contacts. Crowded environments can organize filaments into bundles, but less is known about how they affect F-actin structure. This study used 2D IR spectroscopy and spectral calculations to examine how crowding and bundling impact the secondary structure and local environments in filaments and weakly or strongly bundled networks. The results reveal that bundling induces changes in actin's secondary structure, leading to a decrease in β-sheet and an increase in loop conformations. Strongly bundled networks exhibit a decrease in backbone solvent exposure, with less perturbed α-helices and nearly "locked" β-sheets. Similarly, the loops become less hydrated but maintain a dynamic environment. These findings highlight the role of loop structure in actin network morphology and stability under morphology control by PEG.
Collapse
Affiliation(s)
- Xiaobing Chen
- Department of Chemistry, University of Texas at Austin, Austin, TX, USA
| | - Steven J Roeters
- Department of Chemistry, Aarhus University, Aarhus, Denmark
- Department of Anatomy and Neurosciences, Vrije Universiteit, Amsterdam UMC, Amsterdam, Netherlands
| | - Francis Cavanna
- Department of Physics, University of Texas at Austin, Center for Nonlinear Dynamics, Austin, TX, USA
| | - José Alvarado
- Department of Physics, University of Texas at Austin, Center for Nonlinear Dynamics, Austin, TX, USA
| | - Carlos R Baiz
- Department of Chemistry, University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
2
|
D'Arco A, Di Fabrizio M, Mancini T, Mosetti R, Macis S, Tranfo G, Della Ventura G, Marcelli A, Petrarca M, Lupi S. Secondary Structures of MERS-CoV, SARS-CoV, and SARS-CoV-2 Spike Proteins Revealed by Infrared Vibrational Spectroscopy. Int J Mol Sci 2023; 24:ijms24119550. [PMID: 37298500 DOI: 10.3390/ijms24119550] [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: 02/28/2023] [Revised: 04/28/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
All coronaviruses are characterized by spike glycoproteins whose S1 subunits contain the receptor binding domain (RBD). The RBD anchors the virus to the host cellular membrane to regulate the virus transmissibility and infectious process. Although the protein/receptor interaction mainly depends on the spike's conformation, particularly on its S1 unit, their secondary structures are poorly known. In this paper, the S1 conformation was investigated for MERS-CoV, SARS-CoV, and SARS-CoV-2 at serological pH by measuring their Amide I infrared absorption bands. The SARS-CoV-2 S1 secondary structure revealed a strong difference compared to those of MERS-CoV and SARS-CoV, with a significant presence of extended β-sheets. Furthermore, the conformation of the SARS-CoV-2 S1 showed a significant change by moving from serological pH to mild acidic and alkaline pH conditions. Both results suggest the capability of infrared spectroscopy to follow the secondary structure adaptation of the SARS-CoV-2 S1 to different environments.
Collapse
Affiliation(s)
- Annalisa D'Arco
- Laboratori Nazionali Frascati, National Institute for Nuclear Physics (INFN-LNF), Via E. Fermi 54, 00044 Frascati, Italy
- Department of Physics, University of Rome 'La Sapienza', P.le A. Moro 2, 00185 Rome, Italy
| | - Marta Di Fabrizio
- Laboratory of Biological Electron Microscopy, School of Basic Sciences, Institute of Physics, EPFL & Department of Fundamental Microbiology, Faculty of Biology and Medicine, UNIL, 1015 Lausanne, Switzerland
| | - Tiziana Mancini
- Department of Physics, University of Rome 'La Sapienza', P.le A. Moro 2, 00185 Rome, Italy
| | - Rosanna Mosetti
- Department of Physics, University of Rome 'La Sapienza', P.le A. Moro 2, 00185 Rome, Italy
| | - Salvatore Macis
- Department of Physics, University of Rome 'La Sapienza', P.le A. Moro 2, 00185 Rome, Italy
| | - Giovanna Tranfo
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Monte Porzio Catone, 00078 Rome, Italy
| | - Giancarlo Della Ventura
- Laboratori Nazionali Frascati, National Institute for Nuclear Physics (INFN-LNF), Via E. Fermi 54, 00044 Frascati, Italy
- Department of Science, University Rome Tre, Largo San Leonardo Murialdo 1, 00146 Rome, Italy
| | - Augusto Marcelli
- Laboratori Nazionali Frascati, National Institute for Nuclear Physics (INFN-LNF), Via E. Fermi 54, 00044 Frascati, Italy
- Rome International Centre for Materials Science Superstipes, Via dei Sabelli 119A, 00185 Rome, Italy
| | - Massimo Petrarca
- National Institute for Nuclear Physics Section Rome1, P.le A. Moro 2, 00185 Rome, Italy
- Department of Basic and Applied Sciences for Engineering (SBAI), University of Rome 'La Sapienza', Via Scarpa 16, 00161 Rome, Italy
| | - Stefano Lupi
- Department of Physics, University of Rome 'La Sapienza', P.le A. Moro 2, 00185 Rome, Italy
- National Institute for Nuclear Physics Section Rome1, P.le A. Moro 2, 00185 Rome, Italy
| |
Collapse
|
3
|
O'Neill N, Lima TA, Ferreira FF, Thursch L, Alvarez N, Schweitzer-Stenner R. Forbidden Secondary Structures Found in Gel-Forming Fibrils of Glycylphenylalanylglycine. J Phys Chem B 2022; 126:8080-8093. [PMID: 36194765 DOI: 10.1021/acs.jpcb.2c05010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The zwitterionic l-tripeptide glycylphenylalanylglycine self-assembles into very long crystalline fibrils in an aqueous solution, which causes the formation of an exceptionally strong gel phase (G' ∼ 5 × 106 Pa). The Rietveld refinement analysis of its powder X-ray diffraction (PXRD) pattern reveals a unit cell with four peptides forming a P212121 space group and adopting an inverse polyproline II conformation, that is, a right-handed helical structure that occupies the "forbidden" region of the Ramachandran plot. This unusual structure is stabilized by a plethora of intermolecular interactions facilitated by the large number of different functional groups of the unblocked tripeptide. Comparisons of simulated and experimental Fourier transform infrared and vibrational circular dichroism (VCD) amide I' profiles corroborate the PXRD structure. Our experimental setup reduces the sample to a quasi-two-dimensional network of fibrils. We exploited the influence of this reduced dimensionality on the amide I VCD to identify the main fibril axis. We demonstrate that PXRD, vibrational spectroscopy, and amide I simulations provide a powerful toolset for secondary structure and fibril axis determination.
Collapse
Affiliation(s)
- Nichole O'Neill
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States.,Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Thamires A Lima
- Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Fabio Furlan Ferreira
- Center for Natural and Human Sciences (CCNH), Federal University of ABC (UFABC), Av. Dos Estados, 5001, S622-3, Santo André, São Paulo09210-580, Brazil
| | - Lavenia Thursch
- Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Nicolas Alvarez
- Department of Chemical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| | - Reinhard Schweitzer-Stenner
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania19104, United States
| |
Collapse
|
4
|
Edun DN, Cracchiolo OM, Serrano AL. A theoretical analysis of coherent cross-peaks in polarization selective 2DIR for detection of cross-α fibrils. J Chem Phys 2022; 156:035102. [DOI: 10.1063/5.0070553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dean N. Edun
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Olivia M. Cracchiolo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Arnaldo L. Serrano
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| |
Collapse
|
5
|
Yan H, Dong J, Huang X, Du X. Protein-Gated Upconversion Nanoparticle-Embedded Mesoporous Silica Nanovehicles via Diselenide Linkages for Drug Release Tracking in Real Time and Tumor Chemotherapy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:29070-29082. [PMID: 34101411 DOI: 10.1021/acsami.1c04447] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Two novel stimuli-responsive drug delivery systems (DDSs) were successfully created from bovine serum albumin- or myoglobin-gated upconversion nanoparticle-embedded mesoporous silica nanovehicles (UCNP@mSiO2) via diselenide (Se-Se)-containing linkages. More importantly, multiple roles of each scaffold of the nanovehicles were achieved. The controlled release of the encapsulated drug doxorubicin (DOX) within the mesopores was activated by triple stimuli (acidic pH, glutathione, or H2O2) of tumor microenvironments, owing to the conformation/surface charge changes in proteins or the reductive/oxidative cleavages of the Se-Se bonds. Upon release of DOX, the Förster resonance energy transfer between the UCNP cores and encapsulated DOX was eliminated, resulting in an increase in ratiometric upconversion luminescence for DOX release tracking in real time. The two protein-gated DDSs showed some differences in the drug release performances, relevant to structures and properties of the protein nanogates. The introduction of the Se-Se linkages not only increased the versatility of reductive/oxidative cleavages but also showed less cytotoxicity to all cell lines. The DOX-loaded protein-gated nanovehicles showed the inhibitory effect on tumor growth in tumor-bearing mice and negligible damage/toxicity to the normal tissues. The constructed nanovehicles in a spatiotemporally controlled manner have fascinating prospects in targeted drug delivery for cancer chemotherapy.
Collapse
Affiliation(s)
- Hua Yan
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
- School of Pharmaceutical and Materials Engineering, Taizhou University, Taizhou, Zhejiang Province 318000, People's Republic of China
| | - Jiangtao Dong
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| | - Xuan Huang
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| | - Xuezhong Du
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| |
Collapse
|
6
|
Edington SC, Liu S, Baiz CR. Infrared spectroscopy probes ion binding geometries. Methods Enzymol 2021; 651:157-191. [PMID: 33888203 DOI: 10.1016/bs.mie.2020.12.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Infrared (IR) spectroscopy is a well-established technique for probing the structure, behavior, and surroundings of molecules in their native environments. Its characteristics-most specifically high structural sensitivity, ready applicability to aqueous samples, and broad availability-make it a valuable enzymological technique, particularly for the interrogation of ion binding sites. While IR spectroscopy of the "garden variety" (steady state at room temperature with wild-type proteins) is versatile and powerful in its own right, the combination of IR spectroscopy with specialized experimental schemes for leveraging ultrafast time resolution, protein labeling, and other enhancements further extends this utility. This book chapter provides the fundamental physical background and literature context essential for harnessing IR spectroscopy in the general context of enzymology with specific focus on interrogation of ion binding. Studies of lanthanide ions binding to calmodulin are highlighted as illustrative examples of this process. Appropriate sample preparation, data collection, and spectral interpretation are discussed from a detail-oriented and practical perspective with the goal of facilitating the reader's rapid progression from reading words in a book to collecting and analyzing their own data in the lab.
Collapse
Affiliation(s)
- Sean C Edington
- Department of Chemistry, Yale University, New Haven, CT, United States
| | - Stephanie Liu
- Department of Chemistry, The University of Texas at Austin, Austin, TX, United States
| | - Carlos R Baiz
- Department of Chemistry, The University of Texas at Austin, Austin, TX, United States.
| |
Collapse
|
7
|
Abstract
Infrared difference spectroscopy probes vibrational changes of proteins upon their perturbation. Compared with other spectroscopic methods, it stands out by its sensitivity to the protonation state, H-bonding, and the conformation of different groups in proteins, including the peptide backbone, amino acid side chains, internal water molecules, or cofactors. In particular, the detection of protonation and H-bonding changes in a time-resolved manner, not easily obtained by other techniques, is one of the most successful applications of IR difference spectroscopy. The present review deals with the use of perturbations designed to specifically change the protein between two (or more) functionally relevant states, a strategy often referred to as reaction-induced IR difference spectroscopy. In the first half of this contribution, I review the technique of reaction-induced IR difference spectroscopy of proteins, with special emphasis given to the preparation of suitable samples and their characterization, strategies for the perturbation of proteins, and methodologies for time-resolved measurements (from nanoseconds to minutes). The second half of this contribution focuses on the spectral interpretation. It starts by reviewing how changes in H-bonding, medium polarity, and vibrational coupling affect vibrational frequencies, intensities, and bandwidths. It is followed by band assignments, a crucial aspect mostly performed with the help of isotopic labeling and site-directed mutagenesis, and complemented by integration and interpretation of the results in the context of the studied protein, an aspect increasingly supported by spectral calculations. Selected examples from the literature, predominately but not exclusively from retinal proteins, are used to illustrate the topics covered in this review.
Collapse
|
8
|
Baronio CM, Barth A. The Amide I Spectrum of Proteins-Optimization of Transition Dipole Coupling Parameters Using Density Functional Theory Calculations. J Phys Chem B 2020; 124:1703-1714. [PMID: 32040320 PMCID: PMC7307917 DOI: 10.1021/acs.jpcb.9b11793] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
![]()
The
amide I region of the infrared spectrum is related to the protein
backbone conformation and can provide important structural information.
However, the interpretation of the experimental results is hampered
because the theoretical description of the amide I spectrum is still
under development. Quantum mechanical calculations, for example, using
density functional theory (DFT), can be used to study the amide I
spectrum of small systems, but the high computational cost makes them
inapplicable to proteins. Other approaches that solve the eigenvalues
of the coupled amide I oscillator system are used instead. An important
interaction to be considered is transition dipole coupling (TDC).
Its calculation depends on the parameters of the transition dipole
moment. This work aims to find the optimal parameters for TDC in three
major secondary structures: α-helices, antiparallel β-sheets,
and parallel β-sheets. The parameters were suggested through
a comparison between DFT and TDC calculations. The comparison showed
a good agreement for the spectral shape and for the wavenumbers of
the normal modes for all secondary structures. The matching between
the two methods improved when hydrogen bonding to the amide oxygen
was considered. Optimal parameters for individual secondary structures
were also suggested.
Collapse
Affiliation(s)
- Cesare M Baronio
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 106 91, Sweden
| | - Andreas Barth
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm 106 91, Sweden
| |
Collapse
|
9
|
Dynamical properties of myoglobin in an ultraviscous water-glycerol solvent investigated with elastic neutron scattering and FTIR spectroscopy. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.07.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
10
|
Oil Palm Phenolics Inhibit the In Vitro Aggregation of β-Amyloid Peptide into Oligomeric Complexes. Int J Alzheimers Dis 2018; 2018:7608038. [PMID: 29666700 PMCID: PMC5831689 DOI: 10.1155/2018/7608038] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/23/2017] [Accepted: 12/07/2017] [Indexed: 01/01/2023] Open
Abstract
Alzheimer's disease is a severe neurodegenerative disease characterized by the aggregation of amyloid-β peptide (Aβ) into toxic oligomers which activate microglia and astrocytes causing acute neuroinflammation. Multiple studies show that the soluble oligomers of Aβ42 are neurotoxic and proinflammatory, whereas the monomers and insoluble fibrils are relatively nontoxic. We show that Aβ42 aggregation is inhibited in vitro by oil palm phenolics (OPP), an aqueous extract from the oil palm tree (Elaeis guineensis). The data shows that OPP inhibits stacking of β-pleated sheets, which is essential for oligomerization. We demonstrate the inhibition of Aβ42 aggregation by (1) mass spectrometry; (2) Congo Red dye binding; (3) 2D-IR spectroscopy; (4) dynamic light scattering; (5) transmission electron microscopy; and (6) transgenic yeast rescue assay. In the yeast rescue assay, OPP significantly reduces the cytotoxicity of aggregating neuropeptides in yeast genetically engineered to overexpress these peptides. The data shows that OPP inhibits (1) the aggregation of Aβ into oligomers; (2) stacking of β-pleated sheets; and (3) fibrillar growth and coalescence. These inhibitory effects prevent the formation of neurotoxic oligomers and hold potential as a means to reduce neuroinflammation and neuronal death and thereby may play some role in the prevention or treatment of Alzheimer's disease.
Collapse
|
11
|
Mauck CM, Young RM, Wasielewski MR. Characterization of Excimer Relaxation via Femtosecond Shortwave- and Mid-Infrared Spectroscopy. J Phys Chem A 2017; 121:784-792. [DOI: 10.1021/acs.jpca.6b11388] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Catherine M. Mauck
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Ryan M. Young
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Michael R. Wasielewski
- Department of Chemistry and
Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, United States
| |
Collapse
|
12
|
Hu Q, Laskin J. Secondary Structures of Ubiquitin Ions Soft-Landed onto Self-Assembled Monolayer Surfaces. J Phys Chem B 2016; 120:4927-36. [DOI: 10.1021/acs.jpcb.6b02448] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Qichi Hu
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Julia Laskin
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| |
Collapse
|
13
|
Stevenson P, Tokmakoff A. Distinguishing gramicidin D conformers through two-dimensional infrared spectroscopy of vibrational excitons. J Chem Phys 2015; 142:212424. [PMID: 26049444 PMCID: PMC4401804 DOI: 10.1063/1.4917321] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 03/31/2015] [Indexed: 11/14/2022] Open
Abstract
Gramicidin D is a short peptide which dimerizes to form helical pores, adopting one of two conformations in the process. These conformations differ primarily in number of residues per turn and the hydrogen-bond registry between rungs of the helix. Using amide I 2D infrared (IR) and FTIR, we have demonstrated that it is possible to distinguish between the different conformers of gramicidin D in solution. We show that the spectra observed for this helical peptide bear no resemblance to the spectra of α- or 310-helices and that while the FTIR spectra appear similar to spectra of β-sheets, 2D IR reveals that the observed resonances arise from vibrational modes unlike those observed in β-sheets. We also present an idealized model which reproduces the experimental data with high fidelity. This model is able to explain the polarization-dependence of the experimental 2D IR data. Using this model, we show the coupling between the rungs of the helix dominates the spectra, and as a consequence of this, the number of residues per turn can greatly influence the amide I spectra of gramicidin D.
Collapse
Affiliation(s)
- Paul Stevenson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - Andrei Tokmakoff
- Department of Chemistry, James Frank Institute, and The Institute for Biophysical Dynamics, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, USA
| |
Collapse
|
14
|
Stevenson P, Götz C, Baiz CR, Akerboom J, Tokmakoff A, Vaziri A. Visualizing KcsA conformational changes upon ion binding by infrared spectroscopy and atomistic modeling. J Phys Chem B 2015; 119:5824-31. [PMID: 25861001 PMCID: PMC4428008 DOI: 10.1021/acs.jpcb.5b02223] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of ion binding in the selectivity filter of the potassium channel KcsA is investigated by combining amide I Fourier-transform infrared spectroscopy with structure-based spectral modeling. Experimental difference IR spectra between K(+)-bound KcsA and Na(+)-bound KcsA are in good qualitative agreement with spectra modeled from structural ensembles generated from molecular dynamics simulations. The molecular origins of the vibrational modes contributing to differences in these spectra are determined not only from structural differences in the selectivity filter but also from the pore helices surrounding this region. Furthermore, the coordination of K(+) or Na(+) to carbonyls in the selectivity filter effectively decouples the vibrations of those carbonyls from the rest of the protein, creating local probes of the electrostatic environment. The results suggest that it is necessary to include the influence of the surrounding helices in discussing selectivity and transport in KcsA and, on a more general level, that IR spectroscopy offers a nonperturbative route to studying the structure and dynamics of ion channels.
Collapse
Affiliation(s)
- Paul Stevenson
- †Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, United States.,‡Department of Chemistry, James Frank Institute, and The Institute for Biophysical Dynamics, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States
| | - Christoph Götz
- §Research Institute of Molecular Pathology (IMP), Dr Bohr-Gasse 7, A-1030 Wien, Austria
| | - Carlos R Baiz
- ‡Department of Chemistry, James Frank Institute, and The Institute for Biophysical Dynamics, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States
| | | | - Andrei Tokmakoff
- ‡Department of Chemistry, James Frank Institute, and The Institute for Biophysical Dynamics, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States
| | - Alipasha Vaziri
- §Research Institute of Molecular Pathology (IMP), Dr Bohr-Gasse 7, A-1030 Wien, Austria
| |
Collapse
|
15
|
Panman MR, van Dijk CN, Meuzelaar H, Woutersen S. Communication: Nanosecond folding dynamics of an alpha helix: Time-dependent 2D-IR cross peaks observed using polarization-sensitive dispersed pump-probe spectroscopy. J Chem Phys 2015; 142:041103. [DOI: 10.1063/1.4906456] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Matthijs R. Panman
- Van ’t Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Amsterdam, The Netherlands
| | - Chris N. van Dijk
- Van ’t Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Amsterdam, The Netherlands
| | - Heleen Meuzelaar
- Van ’t Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Amsterdam, The Netherlands
| | - S. Woutersen
- Van ’t Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
16
|
Lórenz-Fonfría VA, Schultz BJ, Resler T, Schlesinger R, Bamann C, Bamberg E, Heberle J. Pre-gating conformational changes in the ChETA variant of channelrhodopsin-2 monitored by nanosecond IR spectroscopy. J Am Chem Soc 2015; 137:1850-61. [PMID: 25584873 DOI: 10.1021/ja5108595] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Light-gated ion permeation by channelrhodopsin-2 (ChR2) relies on the photoisomerization of the retinal chromophore and the subsequent photocycle, leading to the formation (on-gating) and decay (off-gating) of the conductive state. Here, we have analyzed the photocycle of a fast-cycling ChR2 variant (E123T mutation, also known as ChETA), by time-resolved UV/vis, step-scan FT-IR, and tunable quantum cascade laser IR spectroscopies with nanosecond resolution. Pre-gating conformational changes rise with a half-life of 200 ns, silent to UV/vis but detected by IR spectroscopy. They involve changes in the peptide backbone and in the H-bond of the side chain of the critical residue D156. Thus, the P1(500) intermediate must be separated into early and late states. Light-adapted ChR2 contains a mixture of all-trans and 13-cis retinal in a 70:30 ratio which are both photoactive. Analysis of ethylenic and fingerprint vibrations of retinal provides evidence that the 13-cis photocycle recovers in 1 ms. This recovery is faster than channel off-gating and most of the proton transfer reactions, implying that the 13-cis photocycle is of minor functional relevance for ChR2.
Collapse
Affiliation(s)
- Víctor A Lórenz-Fonfría
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
| | | | | | | | | | | | | |
Collapse
|
17
|
Baiz CR, Lin YS, Peng CS, Beauchamp KA, Voelz VA, Pande VS, Tokmakoff A. A molecular interpretation of 2D IR protein folding experiments with Markov state models. Biophys J 2014; 106:1359-70. [PMID: 24655511 DOI: 10.1016/j.bpj.2014.02.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/28/2014] [Accepted: 02/03/2014] [Indexed: 11/24/2022] Open
Abstract
The folding mechanism of the N-terminal domain of ribosomal protein L9 (NTL91-39) is studied using temperature-jump (T-jump) amide I' two-dimensional infrared (2D IR) spectroscopy in combination with spectral simulations based on a Markov state model (MSM) built from millisecond-long molecular dynamics trajectories. The results provide evidence for a compact well-structured folded state and a heterogeneous fast-exchanging denatured state ensemble exhibiting residual secondary structure. The folding rate of 26.4 μs(-1) (at 80°C), extracted from the T-jump response of NTL91-39, compares favorably with the 18 μs(-1) obtained from the MSM. Structural decomposition of the MSM and analysis along the folding coordinate indicates that helix-formation nucleates the global folding. Simulated difference spectra, corresponding to the global folding transition of the MSM, are in qualitative agreement with measured T-jump 2D IR spectra. The experiments demonstrate the use of T-jump 2D IR spectroscopy as a valuable tool for studying protein folding, with direct connections to simulations. The results suggest that in addition to predicting the correct native structure and folding time constant, molecular dynamics simulations carried out with modern force fields provide an accurate description of folding mechanisms in small proteins.
Collapse
Affiliation(s)
- Carlos R Baiz
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Yu-Shan Lin
- Department of Chemistry, Stanford University, Stanford, California
| | - Chunte Sam Peng
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | | | - Vincent A Voelz
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania
| | - Vijay S Pande
- Department of Chemistry, Stanford University, Stanford, California; Biophysics Program, Stanford University, Stanford, California; Department of Structural Biology, Stanford University, Stanford, California
| | - Andrei Tokmakoff
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
| |
Collapse
|
18
|
Małolepsza E, Straub JE. Empirical maps for the calculation of amide I vibrational spectra of proteins from classical molecular dynamics simulations. J Phys Chem B 2014; 118:7848-55. [PMID: 24654732 PMCID: PMC4317051 DOI: 10.1021/jp412827s] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
New sets of parameters (maps) for
calculating amide I vibrational
spectra for proteins through a vibrational exciton model are proposed.
The maps are calculated as a function of electric field and van der
Waals forces on the atoms of peptide bonds, taking into account the
full interaction between peptide bonds and the surrounding environment.
The maps are designed to be employed using data obtained from standard
all-atom molecular simulations without any additional constraints
on the system. Six proteins representing a wide range of sizes and
secondary structure complexity were chosen as a test set. Spectra
calculated for these proteins reproduce experimental data both qualitatively
and quantitatively. The proposed maps lead to spectra that capture
the weak second peak observed in proteins containing β-sheets,
allowing for clear distinction between α-helical and β-sheet
proteins. While the parametrization is specific to the CHARMM force
field, the methodology presented can be readily applied to any empirical
force field.
Collapse
Affiliation(s)
- Edyta Małolepsza
- Department of Chemistry, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | | |
Collapse
|
19
|
Grechko M, Zanni MT. Quantification of transition dipole strengths using 1D and 2D spectroscopy for the identification of molecular structures via exciton delocalization: application to α-helices. J Chem Phys 2013; 137:184202. [PMID: 23163364 DOI: 10.1063/1.4764861] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Vibrational and electronic transition dipole strengths are often good probes of molecular structures, especially in excitonically coupled systems of chromophores. One cannot determine transition dipole strengths using linear spectroscopy unless the concentration is known, which in many cases it is not. In this paper, we report a simple method for measuring transition dipole moments from linear absorption and 2D IR spectra that does not require knowledge of concentrations. Our method is tested on several model compounds and applied to the amide I(') band of a polypeptide in its random coil and α-helical conformation as modulated by the solution temperature. It is often difficult to confidently assign polypeptide and protein secondary structures to random coil or α-helix by linear spectroscopy alone, because they absorb in the same frequency range. We find that the transition dipole strength of the random coil state is 0.12 ± 0.013 D(2), which is similar to a single peptide unit, indicating that the vibrational mode of random coil is localized on a single peptide unit. In an α-helix, the lower bound of transition dipole strength is 0.26 ± 0.03 D(2). When taking into account the angle of the amide I(') transition dipole vector with respect to the helix axis, our measurements indicate that the amide I(') vibrational mode is delocalized across a minimum of 3.5 residues in an α-helix. Thus, one can confidently assign secondary structure based on exciton delocalization through its effect on the transition dipole strength. Our method will be especially useful for kinetically evolving systems, systems with overlapping molecular conformations, and other situations in which concentrations are difficult to determine.
Collapse
Affiliation(s)
- Maksim Grechko
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | | |
Collapse
|
20
|
Reduced steric hindrance and optimized spatial arrangement of carbohydrate ligands in imprinted monolayers for enhanced protein binding. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:792-800. [DOI: 10.1016/j.bbamem.2012.11.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/26/2012] [Accepted: 11/06/2012] [Indexed: 11/20/2022]
|
21
|
Wang X, Huang X, Xin Y, Du X. Myoglobin-directed assemblies of binary monolayers functionalized with iminodiacetic acid ligands at the air-water interface through metal coordination for multivalent protein binding. Phys Chem Chem Phys 2012; 14:5470-8. [PMID: 22415292 DOI: 10.1039/c2cp40104e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Myoglobin binding to the binary monolayers composed of sodium hexadecylimino diacetate and hexadecanol at the air-water interface by means of metal coordination has been investigated using infrared reflection absorption spectroscopy (IRRAS). In the absence of Cu(2+), no myoglobin binding to the binary monolayers was observed. In the presence of Cu(2+), remarkable myoglobin binding to the binary monolayers resulted from the formation of ternary complexes of iminodiacetate (IDA)-Cu(2+)-surface histidine. Myoglobin-directed assemblies of the binary monolayers facilitated multivalent protein binding through lateral rearrangements of the IDA ligands and reorientations of the alkyl chains for enhanced protein binding. Myoglobin binding to and desorption from the binary monolayers could be readily controlled through metal coordination.
Collapse
Affiliation(s)
- Xiaoyu Wang
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China
| | | | | | | |
Collapse
|
22
|
Karjalainen EL, Ersmark T, Barth A. Optimization of Model Parameters for Describing the Amide I Spectrum of a Large Set of Proteins. J Phys Chem B 2012; 116:4831-42. [DOI: 10.1021/jp301095v] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Eeva-Liisa Karjalainen
- Department of Biochemistry and Biophysics,
Arrhenius
Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
| | - Tore Ersmark
- Department of Biochemistry and Biophysics,
Arrhenius
Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
| | - Andreas Barth
- Department of Biochemistry and Biophysics,
Arrhenius
Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
| |
Collapse
|
23
|
Baiz CR, Peng CS, Reppert ME, Jones KC, Tokmakoff A. Coherent two-dimensional infrared spectroscopy: Quantitative analysis of protein secondary structure in solution. Analyst 2012; 137:1793-9. [DOI: 10.1039/c2an16031e] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
24
|
Kamerzell TJ, Esfandiary R, Joshi SB, Middaugh CR, Volkin DB. Protein-excipient interactions: mechanisms and biophysical characterization applied to protein formulation development. Adv Drug Deliv Rev 2011; 63:1118-59. [PMID: 21855584 DOI: 10.1016/j.addr.2011.07.006] [Citation(s) in RCA: 348] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 07/19/2011] [Accepted: 07/26/2011] [Indexed: 12/18/2022]
Abstract
The purpose of this review is to demonstrate the critical importance of understanding protein-excipient interactions as a key step in the rational design of formulations to stabilize and deliver protein-based therapeutic drugs and vaccines. Biophysical methods used to examine various molecular interactions between solutes and protein molecules are discussed with an emphasis on applications to pharmaceutical excipients in terms of their effects on protein stability. Key mechanisms of protein-excipient interactions such as electrostatic and cation-pi interactions, preferential hydration, dispersive forces, and hydrogen bonding are presented in the context of different physical states of the formulation such as frozen liquids, solutions, gels, freeze-dried solids and interfacial phenomenon. An overview of the different classes of pharmaceutical excipients used to formulate and stabilize protein therapeutic drugs is also presented along with the rationale for use in different dosage forms including practical pharmaceutical considerations. The utility of high throughput analytical methodologies to examine protein-excipient interactions is presented in terms of expanding formulation design space and accelerating experimental timelines.
Collapse
Affiliation(s)
- Tim J Kamerzell
- Cardiovascular Research Institute, University of Kansas Medical Center, Kansas City, KS 66160, USA.
| | | | | | | | | |
Collapse
|
25
|
Zheng H, Du X. Multivalent protein binding in carbohydrate-functionalized monolayers through protein-directed rearrangement and reorientation of glycolipids at the air-water interface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2128-35. [PMID: 21640072 DOI: 10.1016/j.bbamem.2011.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 04/05/2011] [Accepted: 04/07/2011] [Indexed: 11/29/2022]
Abstract
Multivalent protein binding plays an important role not only in biological recognition but also in biosensor preparation. Infrared reflection absorption spectroscopy and surface plasmon resonance techniques have been used to investigate concanavalin A (Con A) binding to binary monolayers composed of 1,2-di-O-hexadecyl-sn-glycerol and derived glycolipids with the mannose moieties. The glycolipids in the binary monolayers at the air-water interface underwent both lateral rearrangement and molecular reorientation directed by Con A in the subphase favorable to access of the carbohydrate ligands to protein binding pockets for the formation of multivalent binding sites and the minimization of steric crowding of neighboring ligands for enhanced binding. The amounts of specifically bound proteins in the binary monolayers at the air-water interface were accordingly increased in comparison with those in the initially immobilized monolayers at the air-water interface. The directed rearranged binary monolayers with multivalent protein binding were preserved for the preparation of biosensors.
Collapse
Affiliation(s)
- Haifu Zheng
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University,Nanjing 210093, People's Republic of China
| | | |
Collapse
|
26
|
Karjalainen EL, Ravi HK, Barth A. Simulation of the amide I absorption of stacked β-sheets. J Phys Chem B 2010; 115:749-57. [PMID: 21174476 DOI: 10.1021/jp109918c] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Aggregated β-sheet structures are associated with amyloid and prion diseases. Techniques capable of revealing detailed structural and dynamical information on β-sheet structure are thus of great biomedical and biophysical interest. In this work, the infrared (IR) amide I spectral characteristics of stacked β-sheets were modeled using the transition dipole coupling model. For a test set of β-sheet stacks, the simulated amide I spectrum was analyzed with respect to the following parameters; intersheet distance, relative rotation of the sheets with respect to each other and the effect of number of sheets stacked. The amide I maximum shifts about 5 cm(-1) to higher wavenumbers when the intersheet distance between two identical β-sheets decreases from 20 to 5 Å. Rotation around the normal of one of the sheets relative to the other results in maximum intersheet coupling near 0° and 180°. Upon of rotation from 0° to 90° at an intersheet distance of 9 Å, the amide I maximum shifts about 3 cm(-1). Tilting of one of the sheets by 30° from the normal results in a shift of the amide I maximum by less than 1 cm(-1). When stacking several β-sheets along the normal, the amide I maximum shifts to higher wavenumbers with increasing stack size. The amide I maximum shifts about 6 cm(-1) when stacking four sheets with an intersheet distance of 9 Å. The study provides an aid in the interpretation of the IR amide I region for experiments involving β-sheets and creates awareness of the many effects that determine the spectrum of β-sheet structures.
Collapse
Affiliation(s)
- Eeva-Liisa Karjalainen
- Department of Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, SE-106 91, Sweden
| | | | | |
Collapse
|
27
|
Deflores LP, Ganim Z, Nicodemus RA, Tokmakoff A. Amide I'-II' 2D IR spectroscopy provides enhanced protein secondary structural sensitivity. J Am Chem Soc 2010; 131:3385-91. [PMID: 19256572 DOI: 10.1021/ja8094922] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We demonstrate how multimode 2D IR spectroscopy of the protein amide I' and II' vibrations can be used to distinguish protein secondary structure. Polarization-dependent amide I'-II' 2D IR experiments on poly-l-lysine in the beta-sheet, alpha-helix, and random coil conformations show that a combination of amide I' and II' diagonal and cross peaks can effectively distinguish between secondary structural content, where amide I' infrared spectroscopy alone cannot. The enhanced sensitivity arises from frequency and amplitude correlations between amide II' and amide I' spectra that reflect the symmetry of secondary structures. 2D IR surfaces are used to parametrize an excitonic model for the amide I'-II' manifold suitable to predict protein amide I'-II' spectra. This model reveals that the dominant vibrational interaction contributing to this sensitivity is a combination of negative amide II'-II' through-bond coupling and amide I'-II' coupling within the peptide unit. The empirically determined amide II'-II' couplings do not significantly vary with secondary structure: -8.5 cm(-1) for the beta sheet, -8.7 cm(-1) for the alpha helix, and -5 cm(-1) for the coil.
Collapse
Affiliation(s)
- Lauren P Deflores
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | | | | |
Collapse
|
28
|
Montalvo G, Waegele MM, Shandler S, Gai F, DeGrado WF. Infrared signature and folding dynamics of a helical beta-peptide. J Am Chem Soc 2010; 132:5616-8. [PMID: 20373737 PMCID: PMC2862463 DOI: 10.1021/ja100459a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Synthetic foldamers consisting of beta-amino acids offer excellent model systems for examining the effect of backbone flexibility on the dynamics of protein folding. Herein, we study the folding-unfolding kinetics of a beta-peptide that folds into a 14-helical structure in water. We find that the T-jump induced relaxation kinetics of this peptide occur on the nanosecond time scale and are noticeably slower than those of alanine-based alpha-helical peptides, and additionally, the relaxation rates show a weaker dependence on temperature. These differences appear to indicate that the folding energy landscapes of these peptides are different. In addition, we find that the amide I' band of this beta-peptide exhibits a sharp feature at approximately 1612 cm(-1), which we believe is a distinct infrared reporter of 14-helix.
Collapse
Affiliation(s)
- Geronda Montalvo
- Department of Biochemistry & Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | | | - Scott Shandler
- Department of Biochemistry & Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - William F. DeGrado
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
- Department of Biochemistry & Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| |
Collapse
|
29
|
Ganim Z, Jones KC, Tokmakoff A. Insulin dimer dissociation and unfolding revealed by amide I two-dimensional infrared spectroscopy. Phys Chem Chem Phys 2010; 12:3579-88. [DOI: 10.1039/b923515a] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A structurally sensitive probe of the monomer/dimer equilibrium of insulin was developed using 2DIR spectroscopy and interpreted using calculated spectra.
Collapse
Affiliation(s)
- Ziad Ganim
- Department of Chemistry
- Massachusetts Institute of Technology
- Cambridge
- USA
| | - Kevin C. Jones
- Department of Chemistry
- Massachusetts Institute of Technology
- Cambridge
- USA
| | - Andrei Tokmakoff
- Department of Chemistry
- Massachusetts Institute of Technology
- Cambridge
- USA
| |
Collapse
|
30
|
Zheng H, Du X. Protein-Directed Spatial Rearrangement of Glycolipids at the Air−Water Interface for Bivalent Protein Binding: In Situ Infrared Reflection Absorption Spectroscopy. J Phys Chem B 2009; 114:577-84. [DOI: 10.1021/jp908559n] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Haifu Zheng
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Xuezhong Du
- Key Laboratory of Mesoscopic Chemistry (Ministry of Education), State Key Laboratory of Coordination Chemistry, and School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People’s Republic of China
| |
Collapse
|
31
|
Two-dimensional IR spectroscopy and isotope labeling defines the pathway of amyloid formation with residue-specific resolution. Proc Natl Acad Sci U S A 2009; 106:6614-9. [PMID: 19346479 DOI: 10.1073/pnas.0805957106] [Citation(s) in RCA: 245] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
There is considerable interest in uncovering the pathway of amyloid formation because the toxic properties of amyloid likely stems from prefibril intermediates and not the fully formed fibrils. Using a recently invented method of collecting 2-dimensional infrared spectra and site-specific isotope labeling, we have measured the development of secondary structures for 6 residues during the aggregation process of the 37-residue polypeptide associated with type 2 diabetes, the human islet amyloid polypeptide (hIAPP). By monitoring the kinetics at 6 different labeled sites, we find that the peptides initially develop well-ordered structure in the region of the chain that is close to the ordered loop of the fibrils, followed by formation of the 2 parallel beta-sheets with the N-terminal beta-sheet likely forming before the C-terminal sheet. This experimental approach provides a detailed view of the aggregation pathway of hIAPP fibril formation as well as a general methodology for studying other amyloid forming proteins without the use of structure-perturbing labels.
Collapse
|
32
|
Chung HS, Shandiz A, Sosnick TR, Tokmakoff A. Probing the folding transition state of ubiquitin mutants by temperature-jump-induced downhill unfolding. Biochemistry 2009; 47:13870-7. [PMID: 19053229 DOI: 10.1021/bi801603e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crucial to revealing mechanistic details of protein folding is a characterization of the transition state ensemble and its structural dynamics. To probe the transition state of ubiquitin thermal unfolding, we examine unfolding dynamics and kinetics of wild-type and mutant ubiquitin using time-resolved nonlinear infrared spectroscopy after a nanosecond temperature jump. We observe spectral changes on two different time scales. A fast nonexponential microsecond phase is attributed to downhill unfolding from the transition state region, which is induced by a shift of the barrier due to the rapid temperature change. Slow millisecond changes arise from thermally activated folding and unfolding kinetics. Mutants that stabilize or destabilize beta strands III-V lead to a decreased or increased amplitude of the microsecond phase, indicating that the disruption or weakening of these strands occurs in the transition state. Unfolding features from microseconds to milliseconds can be explained by temperature-dependent changes of a two-dimensional free energy surface constructed by the native contacts between beta strands of the protein. In addition, the results support the possibility of an intermediate state in thermal unfolding.
Collapse
Affiliation(s)
- Hoi Sung Chung
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | | | | |
Collapse
|
33
|
Sullan RMA, Gunari N, Tanur AE, Chan Y, Dickinson GH, Orihuela B, Rittschof D, Walker GC. Nanoscale structures and mechanics of barnacle cement. BIOFOULING 2009; 25:263-275. [PMID: 19180351 DOI: 10.1080/08927010802688095] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Polymerized barnacle glue was studied by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and chemical staining. Nanoscale structures exhibiting rod-shaped, globular and irregularly-shaped morphologies were observed in the bulk cement of the barnacle Amphibalanus amphitrite (=Balanus amphitrite) by AFM. SEM coupled with energy dispersive X-ray (EDX) provided chemical composition information, making evident the organic nature of the rod-shaped nanoscale structures. FTIR spectroscopy gave signatures of beta-sheet and random coil conformations. The mechanical properties of these nanoscale structures were also probed using force spectroscopy and indentation with AFM. Indentation data yielded higher elastic moduli for the rod-shaped structures when compared with the other structures in the bulk cement. Single molecule AFM force-extension curves on the matrix of the bulk cement often exhibited a periodic sawtooth-like profile, observed in both the extend and retract portions of the force curve. Rod-shaped structures stained with amyloid protein-selective dyes (Congo red and thioflavin-T) revealed that about 5% of the bulk cement were amyloids. A dominant 100 kDa cement protein was found to be mechanically agile, using repeating hydrophobic structures that apparently associate within the same protein or with neighbors, creating toughness on the 1-100 nm length scale.
Collapse
|
34
|
Chung HS, Tokmakoff A. Temperature-dependent downhill unfolding of ubiquitin. I. Nanosecond-to-millisecond resolved nonlinear infrared spectroscopy. Proteins 2008; 72:474-87. [PMID: 18384151 DOI: 10.1002/prot.22043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Transient thermal unfolding of ubiquitin is investigated using nonlinear infrared spectroscopy after a nanosecond laser temperature jump (T-jump). The abrupt change in the unfolding free energy surface and the ns time resolution allow us to observe a fast response on ns to micros time-scales, which we attribute to downhill unfolding, before a cross-over to ms kinetics. The downhill unfolding by a sub-population of folded proteins is induced through a shift of the barrier toward the native state. By adjusting the T-jump width, the effect of the initial (T(i)) and final (T(f)) temperature on the unfolding dynamics can be separated. From the amplitude of the fast downhill unfolding, the fractional population prepared at the unfolding transition state is obtained. This population increases with both T(i) and with T(f). A two-state kinetic analysis of the ms refolding provides thermodynamic information about the barrier height. By a combination of the fast and slow unfolding and folding parameters, a quasi-two-state kinetic analysis is performed to calculate the time-dependent population changes of the folded state. This calculation coincides with the experimentally obtained population changes at low temperature but deviations are found in the T-jump from 67 to 78 degrees C. Using temperature-dependent barrier height changes, a temperature Phi value analysis is performed. The result shows a decreasing trend of Phi(T) with temperature, which indicates an increase of the heterogeneity of the transition state. We conclude that ubiquitin unfolds along a well-defined pathway at low temperature which expands with increasing temperature to include multiple routes.
Collapse
Affiliation(s)
- Hoi Sung Chung
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | |
Collapse
|
35
|
Ganim Z, Chung HS, Smith AW, DeFlores LP, Jones KC, Tokmakoff A. Amide I two-dimensional infrared spectroscopy of proteins. Acc Chem Res 2008; 41:432-41. [PMID: 18288813 DOI: 10.1021/ar700188n] [Citation(s) in RCA: 345] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We review two-dimensional infrared (2D IR) spectroscopy of the amide I protein backbone vibration. Amide I modes are known for secondary structural sensitivity derived from their protein-wide delocalization. However, amide I FTIR spectra often display little variation for different proteins due to the broad and featureless line shape that arises from different structural motifs. 2D IR offers increased structural resolution by spreading the spectra over a second frequency dimension to reveal two-dimensional line shapes and cross-peaks. In addition, it carries picosecond time resolution, making it an excellent choice for understanding protein dynamics. In 2D IR spectra, cross peaks arise from anharmonic coupling between vibrations. For example, the spectra of ordered antiparallel beta sheets shows a cross peak between the strong nu perpendicular mode at approximately 1620 cm(-1) and the weaker nu parallel mode at approximately 1680 cm(-1). In proteins with beta-sheet content, disorder spreads the cross peaks into ridges, which gives rise to a "Z"-shaped contour profile. 2D IR spectra of alpha helices show a flattened "figure-8" line shape, and random coils give rise to unstructured, diagonally elongated bands. A distinguishing quality of 2D IR is the availability of accurate structure-based models to calculate spectra from atomistic structures and MD simulations. The amide I region is relatively isolated from other protein vibrations, which allows the spectra to be described by coupled anharmonic local amide I vibrations at each peptide unit. One of the most exciting applications of 2D IR is to study protein unfolding dynamics. While 2D IR has been used to study equilibrium structural changes, it has the time resolution to probe all changes resulting from photoinitiated dynamics. Transient 2D IR has been used to probe downhill protein unfolding and hydrogen bond dynamics in peptides. Because 2D IR spectra can be calculated from folding MD simulations, opportunities arise for making rigorous connections. By introduction of isotope labels, amide I 2D IR spectra can probe site-specific structure with picosecond time resolution. This has been used to reveal local information about picosecond fluctuations and disorder in beta hairpins and peptides. Multimode 2D IR spectroscopy has been used to correlate the structure sensitivity of amide I with amide II to report on solvent accessibility and structural stability in proteins.
Collapse
Affiliation(s)
- Ziad Ganim
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Hoi Sung Chung
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Adam W. Smith
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Lauren P. DeFlores
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Kevin C. Jones
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Andrei Tokmakoff
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| |
Collapse
|
36
|
Chung HS, Ganim Z, Jones KC, Tokmakoff A. Transient 2D IR spectroscopy of ubiquitin unfolding dynamics. Proc Natl Acad Sci U S A 2007; 104:14237-42. [PMID: 17551015 PMCID: PMC1964855 DOI: 10.1073/pnas.0700959104] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Indexed: 11/18/2022] Open
Abstract
Transient two-dimensional infrared (2D IR) spectroscopy is used as a probe of protein unfolding dynamics in a direct comparison of fast unfolding experiments with molecular dynamics simulations. In the experiments, the unfolding of ubiquitin is initiated by a laser temperature jump, and protein structural evolution from nanoseconds to milliseconds is probed using amide I 2D IR spectroscopy. The temperature jump prepares a subensemble near the unfolding transition state, leading to quasi-barrierless unfolding (the "burst phase") before the millisecond activated unfolding kinetics. The burst phase unfolding of ubiquitin is characterized by a loss of the coupling between vibrations of the beta-sheet, a process that manifests itself in the 2D IR spectrum as a frequency blue-shift and intensity decrease of the diagonal and cross-peaks of the sheet's two IR active modes. As the sheet unfolds, increased fluctuations and solvent exposure of the beta-sheet amide groups are also characterized by increases in homogeneous linewidth. Experimental spectra are compared with 2D IR spectra calculated from the time-evolving structures in a molecular dynamics simulation of ubiquitin unfolding. Unfolding is described as a sequential unfolding of strands in ubiquitin's beta-sheet, using two collective coordinates of the sheet: (i) the native interstrand contacts between adjacent beta-strands I and II and (ii) the remaining beta-strand contacts within the sheet. The methods used illustrate the general principles by which 2D IR spectroscopy can be used for detailed dynamical comparisons of experiment and simulation.
Collapse
Affiliation(s)
- Hoi Sung Chung
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Ziad Ganim
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Kevin C. Jones
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Andrei Tokmakoff
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| |
Collapse
|
37
|
Besley NA, Metcalf KA. Computation of the amide I band of polypeptides and proteins using a partial Hessian approach. J Chem Phys 2007; 126:035101. [PMID: 17249900 DOI: 10.1063/1.2426344] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A partial Hessian approximation for the computation of the amide I band of polypeptides and proteins is introduced. This approximation exploits the nature of the amide I band, which is largely localized on the carbonyl groups of the backbone amide residues. For a set of model peptides, harmonic frequencies computed from the Hessian comprising only derivatives of the energy with respect to the displacement of the carbon, oxygen, and nitrogen atoms of the backbone amide groups introduce mean absolute errors of 15 and 10 cm(-1) from the full Hessian values at the Hartree-Fock/STO-3G and density functional theory EDF16-31G(*) levels of theory, respectively. Limiting the partial Hessian to include only derivatives with respect to the displacement of the backbone carbon and oxygen atoms yields corresponding errors of 24 and 22 cm(-1). Both approximations reproduce the full Hessian band profiles well with only a small shift to lower wave number. Computationally, the partial Hessian approximation is used in the solution of the coupled perturbed Hartree-Fock/Kohn-Sham equations and the evaluation of the second derivatives of the electron repulsion integrals. The resulting computational savings are substantial and grow with the size of the polypeptide. At the HF/STO-3G level, the partial Hessian calculation for a polypeptide comprising five tryptophan residues takes approximately 10%-15% of the time for the full Hessian calculation. Using the partial Hessian method, the amide I bands of the constituent secondary structure elements of the protein agitoxin 2 (PDB code 1AGT) are calculated, and the amide I band of the full protein estimated.
Collapse
Affiliation(s)
- Nicholas A Besley
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
| | | |
Collapse
|
38
|
Torii H. Time-Domain Calculations of the Infrared and Polarized Raman Spectra of Tetraalanine in Aqueous Solution. J Phys Chem B 2007; 111:5434-44. [PMID: 17441760 DOI: 10.1021/jp070301w] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The IR and polarized (isotropic and anisotropic) Raman spectra are calculated for the amide I band of tetraalanine ((Ala)4) in aqueous solution by using a time-domain computational method, which includes the effects of the diagonal frequency modulations (of individual peptide groups), the off-diagonal (interpeptide) vibrational couplings, and structural dynamics. It is shown that the calculated band profiles, especially the existence of a large negative noncoincidence effect (i.e., large frequency separations between the IR, isotropic Raman, and anisotropic Raman bands, with the isotropic Raman being higher in frequency), are in reasonable agreement with the experimental results. This negative noncoincidence effect derives from two conditions: the positive coupling between the amide I vibrations of peptide groups and the angle larger than 90 degrees between the transition dipoles of the coupled vibrations. This result means that the dynamically changing structures mainly in the polyproline II and beta-type conformations containing some repeated interconversions obtained from the molecular dynamics calculation are consistent with the existence of a large negative noncoincidence effect, as far as the structures satisfy the above two conditions. It is also shown that the electric fields from solvent water molecules induce larger frequency shifts than those of intrachain interactions, with rapid underdamped oscillatory modulations ( approximately 43 fs) due to the librational motions of water molecules that give rise to motional narrowing effect on the spectra. The reason for the difference from the behavior seen for the O-H stretching mode of liquid water is discussed. The time-domain analysis of the mode identity shows that the system proceeds halfway to complete mode mixing with a similar time scale ( approximately 60 fs), suggesting the importance of the nonadiabatic effect, which is included in a natural way in the present computational method.
Collapse
Affiliation(s)
- Hajime Torii
- Department of Chemistry, School of Education, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
| |
Collapse
|
39
|
Smith AW, Tokmakoff A. Amide I two-dimensional infrared spectroscopy of beta-hairpin peptides. J Chem Phys 2007; 126:045109. [PMID: 17286519 DOI: 10.1063/1.2428300] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this report, spectral simulations and isotope labeling are used to describe the two-dimensional IR spectroscopy of beta-hairpin peptides in the amide I spectral region. 2D IR spectra of Gramicidin S, PG12, Trpzip2 (TZ2), and TZ2-T3(*)T10(*), a dual (13)C(') isotope label, are qualitatively described by a model based on the widely used local mode amide I Hamiltonian. The authors' model includes methods for calculating site energies for individual amide oscillators on the basis of hydrogen bonding, nearest neighbor and long-range coupling between sites, and disorder in the site energy. The dependence of the spectral features on the peptide backbone structure is described using disorder-averaged eigenstates, which are visualized by mapping back onto the local amide I sites. beta-hairpin IR spectra are dominated by delocalized vibrations that vary by the phase of adjacent oscillators parallel and perpendicular to the strands. The dominant nu(perpendicular) band is sensitive to the length of the hairpin and the amount of twisting in the backbone structure, while the nu(parallel) band is composed of several low symmetry modes that delocalize along the strands. The spectra of TZ2-T3(*)T10(*) are used to compare coupling models, from which we conclude that transition charge coupling is superior to transition dipole coupling for amide groups directly hydrogen bound across the beta strands. The 2D IR spectra of TZ2-T3(*)T10(*) are used to resolve the redshifted amide I band and extract the site energy of the labeled groups. This allows the authors to compare several methods for calculating the site energies used in excitonic treatments of the amide I band. Gramicidin S is studied in dimethyl sulfoxide to test the role of solvent on the spectral simulations.
Collapse
Affiliation(s)
- Adam W Smith
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | |
Collapse
|
40
|
Maekawa H, Toniolo C, Broxterman QB, Ge NH. Two-Dimensional Infrared Spectral Signatures of 310- and α-Helical Peptides. J Phys Chem B 2007; 111:3222-35. [PMID: 17388471 DOI: 10.1021/jp0674874] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Two-dimensional infrared (2D IR) spectra of Calpha-alkylated model octapeptides Z-(Aib)8-OtBu, Z-(Aib)5-L-Leu-(Aib)2-OMe, and Z-[L-(alphaMeVal)]8-OtBu have been measured in the amide I region to acquire 2D spectral signatures characteristic of 3(10)- and alpha-helical conformations. Phase-adjusted 2D absorptive spectra recorded with parallel polarizations are dominated by intense diagonal peaks, whereas 2D rephasing spectra obtained at the double-crossed polarization configuration reveal cross-peak patterns that are essential for structure determination. In CDCl3, all three peptides are of the 3(10)-helix conformation and exhibit a doublet cross-peak pattern. In 1,1,1,3,3,3-hexafluoroisopropanol, Z-[L-(alphaMeVal)]8-OtBu undergoes slow acidolysis and 3(10)-to-alpha-helix transition. In the course of this conformational change, its 2D rephasing spectrum evolves from an elongated doublet, characteristic of a distorted 3(10)-helix, to a multiple-peak pattern, after becoming an alpha-helix. The linear IR and 2D absorptive spectra are much less informative in discerning the structural changes. The experimental spectra are compared to simulations based on a vibrational exciton Hamiltonian model. The through-bond and through-space vibrational couplings are modeled by ab initio coupling maps and transition dipole interactions. The local amide I frequency is evaluated by a new approach that takes into account the effects of hydrogen-bond geometry and sites. The static diagonal and off-diagonal disorders are introduced into the Hamiltonian through statistical models to account for conformational fluctuations and inhomogeneous broadening. The sensitivity of cross-peak patterns to different helical conformations and the chain length dependence of the spectral features for short 3(10)- and alpha-helices are discussed.
Collapse
Affiliation(s)
- Hiroaki Maekawa
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | | | | | | |
Collapse
|
41
|
Ganim Z, Tokmakoff A. Spectral signatures of heterogeneous protein ensembles revealed by MD Simulations of 2DIR spectra. Biophys J 2006; 91:2636-46. [PMID: 16844758 PMCID: PMC1562382 DOI: 10.1529/biophysj.106.088070] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Accepted: 06/19/2006] [Indexed: 11/18/2022] Open
Abstract
A model for the calculation of amide I FTIR and 2DIR spectra taking into account fluctuations in hydrogen bonding and structure from molecular dynamics (MD) simulations is tested on three systems. It is found that although the homogeneous lineshape approximation yields satisfactory FTIR spectra, 2DIR spectra are sensitive to the inhomogeneity naturally present in any solvated protein and the common approximations of a static structure and averaged-effect solvent are invalid. By building on the local amide Hamiltonian and incorporating site energy variation with electrostatic-based models and disorder from MD trajectories, good agreement is obtained between calculated and measured 2DIR spectra. The largest contribution to the observed inhomogeneity is found to be the fluctuating site energies, which in turn are most sensitive to the water solvent. With the ability to accurately predict 2DIR spectra from atomistic simulations, new opportunities to test force fields and mechanistic predictions from MD are revealed.
Collapse
Affiliation(s)
- Ziad Ganim
- Department of Chemistry and George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | |
Collapse
|