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Sheikhzadeh A, Safaei M, Fadaei Naeini V, Baghani M, Foroutan M, Baniassadi M. Multiscale modeling of unfolding and bond dissociation of rubredoxin metalloprotein. J Mol Graph Model 2024; 129:108749. [PMID: 38442439 DOI: 10.1016/j.jmgm.2024.108749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 02/20/2024] [Accepted: 02/20/2024] [Indexed: 03/07/2024]
Abstract
Mechanical properties of proteins that have a crucial effect on their operation. This study used a molecular dynamics simulation package to investigate rubredoxin unfolding on the atomic scale. Different simulation techniques were applied, and due to the dissociation of covalent/hydrogen bonds, this protein demonstrates several intermediate states in force-extension behavior. A conceptual model based on the cohesive finite element method was developed to consider the intermediate damages that occur during unfolding. This model is based on force-displacement curves derived from molecular dynamics results. The proposed conceptual model is designed to accurately identify bond rupture points and determine the associated forces. This is achieved by conducting a thorough comparison between molecular dynamics and cohesive finite element results. The utilization of a viscoelastic cohesive zone model allows for the consideration of loading rate effects. This rate-dependent model can be further developed and integrated into the multiscale modeling of large assemblies of metalloproteins, providing a comprehensive understanding of mechanical behavior while maintaining a reduced computational cost.
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Affiliation(s)
- Aliakbar Sheikhzadeh
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 2V4, Canada
| | - Mohammad Safaei
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Vahid Fadaei Naeini
- Division of Machine Elements, Luleå University of Technology, Luleå, SE-97187, Sweden
| | - Mostafa Baghani
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Masumeh Foroutan
- Department of Physical Chemistry, School of Chemistry, College of Science, University of Tehran, Tehran, Iran.
| | - Majid Baniassadi
- School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran; University of Strasbourg, CNRS, ICUBE Laboratory, Strasbourg, France.
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2
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Rane L, Wulffele J, Bourgeois D, Glushonkov O, Mantovanelli AMR, Zala N, Byrdin M. Light-Induced Forward and Reverse Intersystem Crossing in Green Fluorescent Proteins at Cryogenic Temperatures. J Phys Chem B 2023. [PMID: 37235526 DOI: 10.1021/acs.jpcb.3c02971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Combining fluorescence and phosphorescence kinetics, we characterize forward and reverse intersystem crossing (FISC and RISC, respectively) between the singlet and triplet manifolds S ↔ T in photoswitchable (rsEGFP2) and non-photoswitchable (EGFP) green fluorescent proteins upon continuous 488 nm laser excitation at cryogenic temperatures (CTs). Both proteins behave very similarly, with T1 absorption spectra showing a visible peak at 490 nm (10 mM-1 cm-1) and a vibrational progression in the near-infrared (720 to 905 nm). The dark lifetime of T1 is 21-24 ms at 100 K and very weakly temperature-dependent up to 180 K. Above 180 K, T1 lifetimes reduce rapidly to few milliseconds as found at room temperature (RT). FISC and RISC quantum yields are 0.3 and 0.1%, respectively, for both proteins. The light-induced RISC channel becomes faster than the dark reversal at power densities as low as 20 W cm-2. We discuss implications for fluorescence (super resolution-) microscopy at CT and RT.
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Affiliation(s)
- Lukas Rane
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
| | - Jip Wulffele
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
| | - Dominique Bourgeois
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
| | - Oleksandr Glushonkov
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
| | - Angela M R Mantovanelli
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
| | - Ninon Zala
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
| | - Martin Byrdin
- Institut de Biologie Structurale, CNRS, Université Grenoble Alpes, CEA, IBS, 38044 Grenoble, France
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3
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Abstract
X-ray crystallography enables detailed structural studies of proteins to understand and modulate their function. Conducting crystallographic experiments at cryogenic temperatures has practical benefits but potentially limits the identification of functionally important alternative protein conformations that can be revealed only at room temperature (RT). This review discusses practical aspects of preparing, acquiring, and analyzing X-ray crystallography data at RT to demystify preconceived impracticalities that freeze progress of routine RT data collection at synchrotron sources. Examples are presented as conceptual and experimental templates to enable the design of RT-inspired studies; they illustrate the diversity and utility of gaining novel insights into protein conformational landscapes. An integrative view of protein conformational dynamics enables opportunities to advance basic and biomedical research.
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von Stetten D, Giraud T, Carpentier P, Sever F, Terrien M, Dobias F, Juers DH, Flot D, Mueller-Dieckmann C, Leonard GA, de Sanctis D, Royant A. In crystallo optical spectroscopy (icOS) as a complementary tool on the macromolecular crystallography beamlines of the ESRF. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:15-26. [PMID: 25615856 PMCID: PMC4304682 DOI: 10.1107/s139900471401517x] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 06/27/2014] [Indexed: 01/04/2023]
Abstract
The analysis of structural data obtained by X-ray crystallography benefits from information obtained from complementary techniques, especially as applied to the crystals themselves. As a consequence, optical spectroscopies in structural biology have become instrumental in assessing the relevance and context of many crystallographic results. Since the year 2000, it has been possible to record such data adjacent to, or directly on, the Structural Biology Group beamlines of the ESRF. A core laboratory featuring various spectrometers, named the Cryobench, is now in its third version and houses portable devices that can be directly mounted on beamlines. This paper reports the current status of the Cryobench, which is now located on the MAD beamline ID29 and is thus called the ID29S-Cryobench (where S stands for `spectroscopy'). It also reviews the diverse experiments that can be performed at the Cryobench, highlighting the various scientific questions that can be addressed.
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Affiliation(s)
| | - Thierry Giraud
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
| | | | - Franc Sever
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
| | - Maxime Terrien
- Université Grenoble Alpes, IBS, F-38044 Grenoble, France
- CNRS, IBS, F-38044 Grenoble, France
- CEA, IBS, F-38044 Grenoble, France
| | - Fabien Dobias
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
| | - Douglas H. Juers
- Department of Physics, Whitman College, Walla Walla, WA 99362, USA
| | - David Flot
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
| | | | | | | | - Antoine Royant
- European Synchrotron Radiation Facility, F-38043 Grenoble, France
- Université Grenoble Alpes, IBS, F-38044 Grenoble, France
- CNRS, IBS, F-38044 Grenoble, France
- CEA, IBS, F-38044 Grenoble, France
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5
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Warkentin M, Hopkins JB, Haber JB, Blaha G, Thorne RE. Temperature-dependent radiation sensitivity and order of 70S ribosome crystals. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2890-6. [PMID: 25372680 PMCID: PMC4220972 DOI: 10.1107/s1399004714017672] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 08/01/2014] [Indexed: 11/10/2022]
Abstract
All evidence to date indicates that at T = 100 K all protein crystals exhibit comparable sensitivity to X-ray damage when quantified using global metrics such as change in scaling B factor or integrated intensity versus dose. This is consistent with observations in cryo-electron microscopy, and results because nearly all diffusive motions of protein and solvent, including motions induced by radiation damage, are frozen out. But how do the sensitivities of different proteins compare at room temperature, where radiation-induced radicals are free to diffuse and protein and lattice structures are free to relax in response to local damage? It might be expected that a large complex with extensive conformational degrees of freedom would be more radiation sensitive than a small, compact globular protein. As a test case, the radiation sensitivity of 70S ribosome crystals has been examined. At T = 100 and 300 K, the half doses are 64 MGy (at 3 Å resolution) and 150 kGy (at 5 Å resolution), respectively. The maximum tolerable dose in a crystallography experiment depends upon the initial or desired resolution. When differences in initial data-set resolution are accounted for, the former half dose is roughly consistent with that for model proteins, and the 100/300 K half-dose ratio is roughly a factor of ten larger. 70S ribosome crystals exhibit substantially increased resolution at 100 K relative to 300 K owing to cooling-induced ordering and not to reduced radiation sensitivity and slower radiation damage.
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Affiliation(s)
| | | | - Jonah B. Haber
- Physics Department, Cornell University, Ithaca, NY 14853, USA
| | - Gregor Blaha
- Department of Biochemistry, University of California, Riverside, CA 92521, USA
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Gregory MJ, Anderson M, Causgrove TP. Measurement of energy barriers to conformational change in poly-l-glutamic acid by temperature-derivative spectroscopy. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2013.04.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Warkentin M, Badeau R, Hopkins JB, Thorne RE. Spatial distribution of radiation damage to crystalline proteins at 25-300 K. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1108-17. [PMID: 22948911 PMCID: PMC3489100 DOI: 10.1107/s0907444912021361] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 05/10/2012] [Indexed: 11/11/2022]
Abstract
The spatial distribution of radiation damage (assayed by increases in atomic B factors) to thaumatin and urease crystals at temperatures ranging from 25 to 300 K is reported. The nature of the damage changes dramatically at approximately 180 K. Above this temperature the role of solvent diffusion is apparent in thaumatin crystals, as solvent-exposed turns and loops are especially sensitive. In urease, a flap covering the active site is the most sensitive part of the molecule and nearby loops show enhanced sensitivity. Below 180 K sensitivity is correlated with poor local packing, especially in thaumatin. At all temperatures, the component of the damage that is spatially uniform within the unit cell accounts for more than half of the total increase in the atomic B factors and correlates with changes in mosaicity. This component may arise from lattice-level, rather than local, disorder. The effects of primary structure on radiation sensitivity are small compared with those of tertiary structure, local packing, solvent accessibility and crystal contacts.
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Affiliation(s)
| | - Ryan Badeau
- Physics Department, Cornell University, Ithaca, NY 14853, USA
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Warkentin M, Badeau R, Hopkins J, Thorne RE. Dark progression reveals slow timescales for radiation damage between T = 180 and 240 K. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2011; 67:792-803. [PMID: 21904032 PMCID: PMC3169314 DOI: 10.1107/s0907444911027600] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 07/09/2011] [Indexed: 11/11/2022]
Abstract
Can radiation damage to protein crystals be `outrun' by collecting a structural data set before damage is manifested? Recent experiments using ultra-intense pulses from a free-electron laser show that the answer is yes. Here, evidence is presented that significant reductions in global damage at temperatures above 200 K may be possible using conventional X-ray sources and current or soon-to-be available detectors. Specifically, `dark progression' (an increase in damage with time after the X-rays have been turned off) was observed at temperatures between 180 and 240 K and on timescales from 200 to 1200 s. This allowed estimation of the temperature-dependent timescale for damage. The rate of dark progression is consistent with an Arrhenius law with an activation energy of 14 kJ mol(-1). This is comparable to the activation energy for the solvent-coupled diffusive damage processes responsible for the rapid increase in radiation sensitivity as crystals are warmed above the glass transition near 200 K. Analysis suggests that at T = 300 K data-collection times of the order of 1 s (and longer at lower temperatures) may allow significant reductions in global radiation damage, facilitating structure solution on crystals with liquid solvent. No dark progression was observed below T = 180 K, indicating that no important damage process is slowed through this timescale window in this temperature range.
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Affiliation(s)
| | - Ryan Badeau
- Physics Department, Cornell University, Ithaca, NY 14853, USA
| | - Jesse Hopkins
- Physics Department, Cornell University, Ithaca, NY 14853, USA
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9
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Warkentin M, Thorne RE. Glass transition in thaumatin crystals revealed through temperature-dependent radiation-sensitivity measurements. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2010; 66:1092-100. [PMID: 20944242 PMCID: PMC2954455 DOI: 10.1107/s0907444910035523] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 09/03/2010] [Indexed: 11/10/2022]
Abstract
The temperature-dependence of radiation damage to thaumatin crystals between T = 300 and 100 K is reported. The amount of damage for a given dose decreases sharply as the temperature decreases from 300 to 220 K and then decreases more gradually on further cooling below the protein-solvent glass transition. Two regimes of temperature-activated behavior were observed. At temperatures above ∼200 K the activation energy of 18.0 kJ mol(-1) indicates that radiation damage is dominated by diffusive motions in the protein and solvent. At temperatures below ∼200 K the activation energy is only 1.00 kJ mol(-1), which is of the order of the thermal energy. Similar activation energies describe the temperature-dependence of radiation damage to a variety of solvent-free small-molecule organic crystals over the temperature range T = 300-80 K. It is suggested that radiation damage in this regime is vibrationally assisted and that the freezing-out of amino-acid scale vibrations contributes to the very weak temperature-dependence of radiation damage below ∼80 K. Analysis using the radiation-damage model of Blake and Phillips [Blake & Phillips (1962), Biological Effects of Ionizing Radiation at the Molecular Level, pp. 183-191] indicates that large-scale conformational and molecular motions are frozen out below T = 200 K but become increasingly prevalent and make an increasing contribution to damage at higher temperatures. Possible alternative mechanisms for radiation damage involving the formation of hydrogen-gas bubbles are discussed and discounted. These results have implications for mechanistic studies of proteins and for studies of the protein glass transition. They also suggest that data collection at T ≃ 220 K may provide a viable alternative for structure determination when cooling-induced disorder at T = 100 is excessive.
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10
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Nienhaus K, Nienhaus GU. Ligand dynamics in heme proteins observed by Fourier transform infrared-temperature derivative spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:1030-41. [PMID: 20656073 DOI: 10.1016/j.bbapap.2010.07.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 07/14/2010] [Accepted: 07/15/2010] [Indexed: 11/29/2022]
Abstract
Fourier transform infrared (FTIR) spectroscopy is a powerful tool for the investigation of protein-ligand interactions in heme proteins. Nitric oxide and carbon monoxide are attractive physiologically relevant ligands because their bond stretching vibrations give rise to strong mid-infrared absorption bands that can be measured with exquisite sensitivity and precision using photolysis difference spectroscopy at cryogenic temperatures. These stretching bands are fine-tuned by electrostatic interactions with the environment and, therefore, ligands can be utilized as local probes of structure and dynamics. Bound to the heme iron, the ligand stretching bands are susceptible to changes in the iron-ligand bond and the electric field at the active site. Upon photolysis, the vibrational bands display changes due to ligand relocation to docking sites within the protein, rotational motions of the ligand in these sites and protein conformational changes. Photolysis difference spectra taken over a wide temperature range (3-300K) using specific temperature protocols for sample photodissociation can provide detailed insights into both protein and ligand dynamics. Moreover, temperature-derivative spectroscopy (TDS) has proven to be a particularly powerful technique to study protein-ligand interactions. The FTIR-TDS technique has been extensively applied to studies of carbon monoxide binding to heme proteins, whereas measurements with nitric oxide are still scarce. Here we describe infrared cryo-spectroscopy and present a variety of applications to the study of protein-ligand interactions in heme proteins. This article is part of a Special Issue entitled: Protein Dynamics: Experimental and Computational Approaches.
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Affiliation(s)
- Karin Nienhaus
- Karlsruhe Institute of Technology (KIT), Institute of Applied Physics and Center for Functional Nanostructures, Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe, Germany
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11
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Zang C, Stevens JA, Link JJ, Guo L, Wang L, Zhong D. Ultrafast proteinquake dynamics in cytochrome c. J Am Chem Soc 2010; 131:2846-52. [PMID: 19203189 DOI: 10.1021/ja8057293] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report here our systematic studies of the heme dynamics and induced protein conformational relaxations in two redox states of ferric and ferrous cytochrome c upon femtosecond excitation. With a wide range of probing wavelengths from the visible to the UV and a site-directed mutation we unambiguously determined that the protein dynamics in the two states are drastically different. For the ferrous state the heme transforms from 6-fold to 5-fold coordination with ultrafast ligand dissociation in less than 100 fs, followed by vibrational cooling within several picoseconds, but then recombining back to its original 6-fold coordination in 7 ps. Such impulsive bond breaking and late rebinding generate proteinquakes and strongly perturb the local heme site and shake global protein conformation, which were found to completely recover in 13 and 42 ps, respectively. For the ferric state the heme however maintains its 6-fold coordination. The dynamics mainly occur at the local site, including ultrafast internal conversion in hundreds of femtoseconds, vibrational cooling on the similar picosecond time scale, and complete ground-state recovery in 10 ps, and no global conformation relaxation was observed.
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Affiliation(s)
- Chen Zang
- Department of Physics, Program of Biophysics, The Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio, 43210, USA
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12
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Bourgeois D, Katona G, de Rosny E, Carpentier P. Raman-assisted X-ray crystallography for the analysis of biomolecules. Methods Mol Biol 2009; 544:253-67. [PMID: 19488704 DOI: 10.1007/978-1-59745-483-4_16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
In this chapter, we describe Raman microspectrophotometry applied to crystals of biomolecules. Raman spectra collected in crystallo provide structural information highly complementary to X-ray diffraction, relate the crystalline state to the solution state, and allow the identification of ligand-bound or intermediate states of macromolecules. Nonresonant Raman spectroscopy is particularly suitable to the study of macromolecular crystals, and therefore applies to a wide range of noncolored crystalline proteins. Practical issues related to the investigation of crystals by Raman microspectrophotometry are reviewed, and the current limitations are highlighted.
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Affiliation(s)
- Dominique Bourgeois
- Institut de Biologie Structurale Jean-Pierre Ebel, 41 Rue Jules Horowitz, 38027, Grenoble Cedex, France.
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13
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Warkentin M, Thorne RE. Slow cooling of protein crystals. J Appl Crystallogr 2009; 42:944-952. [PMID: 19798409 DOI: 10.1107/s0021889809023553] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 06/19/2009] [Indexed: 11/10/2022] Open
Abstract
Cryoprotectant-free thaumatin crystals have been cooled from 300 to 100 K at a rate of 0.1 K s(-1) - 10(3)-10(4) times slower than in conventional flash cooling - while continuously collecting X-ray diffraction data, so as to follow the evolution of protein lattice and solvent properties during cooling. Diffraction patterns show no evidence of crystalline ice at any temperature. This indicates that the lattice of protein molecules is itself an excellent cryoprotectant, and with sodium potassium tartrate incorporated from the 1.5 M mother liquor ice nucleation rates are at least as low as in a 70% glycerol solution. Crystal quality during slow cooling remains high, with an average mosaicity at 100 K of 0.2 degrees . Most of the mosaicity increase occurs above approximately 200 K, where the solvent is still liquid, and is concurrent with an anisotropic contraction of the unit cell. Near 180 K a crossover to solid-like solvent behavior occurs, and on further cooling there is no additional degradation of crystal order. The variation of B factor with temperature shows clear evidence of a protein dynamical transition near 210 K, and at lower temperatures the slope dB/dT is a factor of 3-6 smaller than has been reported for any other protein. These results establish the feasibility of fully temperature controlled studies of protein structure and dynamics between 300 and 100 K.
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14
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Durin G, Delaunay A, Darnault C, Heyes DJ, Royant A, Vernede X, Hunter CN, Weik M, Bourgeois D. Simultaneous measurements of solvent dynamics and functional kinetics in a light-activated enzyme. Biophys J 2009; 96:1902-10. [PMID: 19254549 DOI: 10.1016/j.bpj.2008.10.065] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 10/31/2008] [Indexed: 10/21/2022] Open
Abstract
Solvent fluctuations play a key role in controlling protein motions and biological function. Here, we have studied how individual steps of the reaction catalyzed by the light-activated enzyme protochlorophyllide oxidoreductase (POR) couple with solvent dynamics. To simultaneously monitor the catalytic cycle of the enzyme and the dynamical behavior of the solvent, we designed temperature-dependent UV-visible microspectrophotometry experiments, using flash-cooled nanodroplets of POR to which an exogenous soluble fluorophore was added. The formation and decay of the first two intermediates in the POR-catalyzed reaction were measured, together with the solvent glass transition and the buildup of crystalline ice at cryogenic temperatures. We find that formation of the first intermediate occurs below the glass transition temperature (T(g)), and is not affected by changes in solvent dynamics induced by modifying the glycerol content. In contrast, formation of the second intermediate occurs above T(g) and is influenced by changes in glycerol concentration in a manner remarkably similar to the buildup of crystalline ice. These results suggest that internal, nonslaved protein motions drive the first step of the POR-catalyzed reaction whereas solvent-slaved motions control the second step. We propose that the concept of solvent slaving applies to complex enzymes such as POR.
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Affiliation(s)
- Guillaume Durin
- Institut de Biologie Structurale Jean-Pierre Ebel, Centre d'Etudes Atomiques, Centre National de la Recherche Scientifique, Université Joseph Fourier, Grenoble, France
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15
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Bourgeois D, Weik M. Kinetic protein crystallography: a tool to watch proteins in action. CRYSTALLOGR REV 2009. [DOI: 10.1080/08893110802604868] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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McGeehan J, Ravelli RBG, Murray JW, Owen RL, Cipriani F, McSweeney S, Weik M, Garman EF. Colouring cryo-cooled crystals: online microspectrophotometry. JOURNAL OF SYNCHROTRON RADIATION 2009; 16:163-72. [PMID: 19240328 PMCID: PMC2651762 DOI: 10.1107/s0909049509001629] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Accepted: 01/13/2009] [Indexed: 05/17/2023]
Abstract
X-rays can produce a high concentration of radicals within cryo-cooled macromolecular crystals. Some radicals have large extinction coefficients in the visible (VIS) range of the electromagnetic spectrum, and can be observed optically and spectrally. An online microspectrophotometer with high temporal resolution has been constructed that is capable of measuring UV/VIS absorption spectra (200-1100 nm) during X-ray data collection. The typical X-ray-induced blue colour that is characteristic of a wide range of cryo-conditions has been identified as trapped solvated electrons. Disulphide-containing proteins are shown to form disulphide radicals at millimolar concentrations, with absorption maxima around 400 nm. The solvated electrons and the disulphide radicals seem to have a lifetime in the range of seconds up to minutes at 100 K. The temperature dependence of the kinetics of X-ray-induced radical formation is different for the solvated electrons compared with the disulphide radicals. The online microspectrophotometer provides a technique complementary to X-ray diffraction for analysing and characterizing intermediates and redox states of proteins and enzymes.
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Affiliation(s)
- John McGeehan
- EMBL, 6 rue Jules Horowitz, 38042 Grenoble, France
- Biophysics Laboratories, School of Biological Sciences, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
| | - Raimond B. G. Ravelli
- EMBL, 6 rue Jules Horowitz, 38042 Grenoble, France
- Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center (LUMC), PO Box 9600, 2300RC Leiden, The Netherlands
- Correspondence e-mail: ,
| | - James W. Murray
- Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Imperial College, Exhibition Road, London SW7 2AZ, UK
| | - Robin Leslie Owen
- Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | | | | | - Martin Weik
- Laboratoire de Biophysique Moléculaire, Institut de Biologie Structurale, Jean Pierre EBEL, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1, France
| | - Elspeth F. Garman
- Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
- Correspondence e-mail: ,
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17
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Picometer-scale conformational heterogeneity separates functional from nonfunctional states of a photoreceptor protein. Structure 2008; 16:863-72. [PMID: 18547519 DOI: 10.1016/j.str.2008.02.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 02/27/2008] [Accepted: 02/27/2008] [Indexed: 11/23/2022]
Abstract
Protein structural fluctuations occur over a wide spatial scale, ranging from minute, picometer-scale displacements, to large, interdomain motions and partial unfolding. While large-scale protein structural changes and their effects on protein function have been the focus of much recent attention, small-scale fluctuations have been less well studied, and are generally assumed to have proportionally smaller effects. Here we use the bacterial photoreceptor photoactive yellow protein (PYP) to test if subtle structural changes do, indeed, imply equally subtle functional effects. We flash froze crystals of PYP to trap the protein's conformational ensemble, and probed the molecules in this ensemble for their ability to facilitate PYP's biological function (i.e., light-driven isomerization of its chromophore). Our results indicate that the apparently homogeneous structural state observed in a 0.82 A crystal structure in fact comprises an ensemble of conformational states, in which subpopulations with nearly identical structures display dramatically different functional properties.
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Coureux PD, Genick UK. Triggering and Monitoring Light‐Sensing Reactions in Protein Crystals. Methods Enzymol 2007; 422:305-37. [PMID: 17628146 DOI: 10.1016/s0076-6879(06)22015-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Many bacterial photoreceptors signal via histidine kinases. The light-activated nature of these proteins provides unique experimental opportunities to study their molecular mechanisms of signal transduction. One of these opportunities is the combined application of X-ray crystallography and optical spectroscopy in protein crystals. By combining these two methods it is possible to correlate protein structure to protein function in a way that is exceedingly difficult or impossible to achieve in most other experimental systems. This chapter is divided into two parts. The first part provides a brief overview of light-regulated histidine kinases and the most important techniques for studying the structure of photocycle intermediates by crystallography. The second part of the chapter is dedicated to practical advice on how to select, mount, activate, and monitor the structural and spectroscopic responses of photoreceptor crystals. This chapter is intended for readers who want to start using these experimental tools themselves or who wish to understand enough about the techniques to critically evaluate the work of others.
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Warkentin M, Berejnov V, Husseini NS, Thorne RE. Hyperquenching for protein cryocrystallography. J Appl Crystallogr 2006; 39:805-811. [PMID: 20461232 PMCID: PMC2866519 DOI: 10.1107/s0021889806037484] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Accepted: 09/14/2006] [Indexed: 11/10/2022] Open
Abstract
When samples having volumes characteristic of protein crystals are plunge cooled in liquid nitrogen or propane, most cooling occurs in the cold gas layer above the liquid. By removing this cold gas layer, cooling rates for small samples and modest plunge velocities are increased to 1.5 × 10(4) K s(-1), with increases of a factor of 100 over current best practice possible with 10 μm samples. Glycerol concentrations required to eliminate water crystallization in protein-free aqueous mixtures drop from ∼28% w/v to as low as 6% w/v. These results will allow many crystals to go from crystallization tray to liquid cryogen to X-ray beam without cryoprotectants. By reducing or eliminating the need for cryoprotectants in growth solutions, they may also simplify the search for crystallization conditions and for optimal screens. The results presented here resolve many puzzles, such as why plunge cooling in liquid nitrogen or propane has, until now, not yielded significantly better diffraction quality than gas-stream cooling.
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Affiliation(s)
| | | | - Naji S. Husseini
- Applied and Engineering Physics Department, Cornell University, Ithaca, NY 14853, USA
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20
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Klink BU, Goody RS, Scheidig AJ. A newly designed microspectrofluorometer for kinetic studies on protein crystals in combination with x-ray diffraction. Biophys J 2006; 91:981-92. [PMID: 16698776 PMCID: PMC1563776 DOI: 10.1529/biophysj.105.078931] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a new design for a fluorescence microspectrophotometer for use in kinetic crystallography in combination with x-ray diffraction experiments. The FLUMIX device (Fluorescence spectroscopy to monitor intermediates in x-ray crystallography) is built for 0 degrees fluorescence detection, which has several advantages in comparison to a conventional fluorometer with 90 degrees design. Due to the reduced spatial requirements and the need for only one objective, the system is highly versatile, easy to handle, and can be used for many different applications. In combination with a conventional stereomicroscope, fluorescence measurements or reaction initiation can be performed directly in a hanging drop crystallization setup. The FLUMIX device can be combined with most x-ray sources, normally without the need of a specialized mechanical support. As a biological model system, we have used H-Ras p21 with an artificially introduced photo-labile GTP precursor (caged GTP) and a covalently attached fluorophore (IANBD amide). Using the FLUMIX system, detailed information about the state of photolyzed crystals of the modified H-Ras p21 (p21(mod)) could be obtained. Measurements in combination with a synchrotron beamline showed significant fluorescence changes in p21(mod) crystals even within a few seconds of x-ray exposure at 100 K.
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Affiliation(s)
- Björn U Klink
- Max-Planck-Institut für Molekulare Physiologie, Abteilung Physikalische Biochemie, D-44225 Dortmund, Germany
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Bourgeois D, Royant A. Advances in kinetic protein crystallography. Curr Opin Struct Biol 2006; 15:538-47. [PMID: 16129597 DOI: 10.1016/j.sbi.2005.08.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 07/09/2005] [Accepted: 08/18/2005] [Indexed: 10/25/2022]
Abstract
Many proteins function in the crystalline state, making crystallography a tool that can address mechanism, as well as structure. By initiating biological turnover in the crystal, transient structural species form, which may be filmed by Laue diffraction or captured by freeze-trapping methods. Laue diffraction has now reached an unprecedented level of sophistication and has found a 'niche of excellence' in the study of cyclic, ultra-fast, light-triggered reactions. Trapping methods, on the other hand, are more generally applicable, but require care to avoid artifacts. New strategies have been developed and difficulties such as radiation damage have received particular attention. Complementary methods--mainly UV/visible single-crystal spectroscopy--have proven essential to design, interpret and validate kinetic crystallography experiments.
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Affiliation(s)
- Dominique Bourgeois
- LCCP, UMR 5075, IBS, 41 avenue Jules Horowitz, 38027 Grenoble Cedex 1, France.
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22
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Abstract
For several decades, single-crystal microspectrophotometry has contributed to structural enzymology as a very useful complement to X-ray crystallography. In its most recent applications, it is the ideal tool to track chemistry as structure evolves in the course of time-resolved experiments, to identify freeze-trapped catalytic intermediates and to assess radiation-induced effects on enzyme crystals. To these goals, instruments have been developed to record optical spectra 'on-line' in the course of X-ray data collection, whereas more rigorous polarized absorption studies 'off-line' play an essential role in describing what protein function is retained in the crystalline state and correlating it with the observed structures.
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Affiliation(s)
- Arwen R Pearson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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