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Khusainov G, Standfuss J, Weinert T. The time revolution in macromolecular crystallography. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:020901. [PMID: 38616866 PMCID: PMC11015943 DOI: 10.1063/4.0000247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 03/18/2024] [Indexed: 04/16/2024]
Abstract
Macromolecular crystallography has historically provided the atomic structures of proteins fundamental to cellular functions. However, the advent of cryo-electron microscopy for structure determination of large and increasingly smaller and flexible proteins signaled a paradigm shift in structural biology. The extensive structural and sequence data from crystallography and advanced sequencing techniques have been pivotal for training computational models for accurate structure prediction, unveiling the general fold of most proteins. Here, we present a perspective on the rise of time-resolved crystallography as the new frontier of macromolecular structure determination. We trace the evolution from the pioneering time-resolved crystallography methods to modern serial crystallography, highlighting the synergy between rapid detection technologies and state-of-the-art x-ray sources. These innovations are redefining our exploration of protein dynamics, with high-resolution crystallography uniquely positioned to elucidate rapid dynamic processes at ambient temperatures, thus deepening our understanding of protein functionality. We propose that the integration of dynamic structural data with machine learning advancements will unlock predictive capabilities for protein kinetics, revolutionizing dynamics like macromolecular crystallography revolutionized structural biology.
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Affiliation(s)
- Georgii Khusainov
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Joerg Standfuss
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Tobias Weinert
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
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2
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Henning RW, Kosheleva I, Šrajer V, Kim IS, Zoellner E, Ranganathan R. BioCARS: Synchrotron facility for probing structural dynamics of biological macromolecules. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:014301. [PMID: 38304444 PMCID: PMC10834067 DOI: 10.1063/4.0000238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 01/10/2024] [Indexed: 02/03/2024]
Abstract
A major goal in biomedical science is to move beyond static images of proteins and other biological macromolecules to the internal dynamics underlying their function. This level of study is necessary to understand how these molecules work and to engineer new functions and modulators of function. Stemming from a visionary commitment to this problem by Keith Moffat decades ago, a community of structural biologists has now enabled a set of x-ray scattering technologies for observing intramolecular dynamics in biological macromolecules at atomic resolution and over the broad range of timescales over which motions are functionally relevant. Many of these techniques are provided by BioCARS, a cutting-edge synchrotron radiation facility built under Moffat leadership and located at the Advanced Photon Source at Argonne National Laboratory. BioCARS enables experimental studies of molecular dynamics with time resolutions spanning from 100 ps to seconds and provides both time-resolved x-ray crystallography and small- and wide-angle x-ray scattering. Structural changes can be initiated by several methods-UV/Vis pumping with tunable picosecond and nanosecond laser pulses, substrate diffusion, and global perturbations, such as electric field and temperature jumps. Studies of dynamics typically involve subtle perturbations to molecular structures, requiring specialized computational techniques for data processing and interpretation. In this review, we present the challenges in experimental macromolecular dynamics and describe the current state of experimental capabilities at this facility. As Moffat imagined years ago, BioCARS is now positioned to catalyze the scientific community to make fundamental advances in understanding proteins and other complex biological macromolecules.
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Affiliation(s)
- Robert W. Henning
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - Irina Kosheleva
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - Vukica Šrajer
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - In-Sik Kim
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - Eric Zoellner
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - Rama Ranganathan
- BioCARS, Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
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3
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Kim Y, Ganesan P, Jo J, Kim SO, Thamilselvan K, Ihee H. Chromophore-Removal-Induced Conformational Change in Photoactive Yellow Protein Determined through Spectroscopic and X-ray Solution Scattering Studies. J Phys Chem B 2018; 122:4513-4520. [PMID: 29648836 DOI: 10.1021/acs.jpcb.8b01768] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photoactive yellow protein (PYP) induces negative phototaxis in Halorhodospira halophila via photoactivation triggered by light-mediated chromophore isomerization. Chromophore isomerization proceeds via a volume-conserving isomerization mechanism due to the hydrogen-bond network and steric constraints inside the protein, and causes significant conformational changes accompanied by N-terminal protrusion. However, it is unclear how the structural change of the chromophore affects the remote N-terminal domain. To understand photocycle-related structural changes, we investigated the structural aspect of chromophore removal in PYP because it possesses a disrupted hydrogen-bond network similar to that in photocycle intermediates. A comparison of the structural aspects with those observed in the photocycle would give a clue related to the structural change mechanism in the photocycle. Chromophore removal effects were assessed via UV-vis spectroscopy, circular dichroism, and X-ray solution scattering. Molecular shape reconstruction and an experiment-restrained rigid-body molecular dynamics simulation based on the scattering data were performed to determine protein shape, size, and conformational changes upon PYP bleaching. Data show that chromophore removal disrupted the holo-PYP structure, resulting in a small N-terminal protrusion, but the extent of conformational changes was markedly less than those in the photocycle. This indicates that disruption of the hydrogen-bond network alone in bleached PYP does not induce the large conformational change observed in the photocycle, which thus must result from the organized structural transition around the chromophore triggered by chromophore photoisomerization along with disruption of the hydrogen-bond network between the chromophore and the PYP core.
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Affiliation(s)
- Youngmin Kim
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Prabhakar Ganesan
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
| | - Junbeom Jo
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Seong Ok Kim
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Kamatchi Thamilselvan
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea.,Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
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4
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Schmidt M. A short history of structure based research on the photocycle of photoactive yellow protein. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:032201. [PMID: 28191482 PMCID: PMC5291790 DOI: 10.1063/1.4974172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/04/2017] [Indexed: 05/07/2023]
Abstract
The goals of time-resolved macromolecular crystallography are to extract the molecular structures of the reaction intermediates and the reaction dynamics from time-resolved X-ray data alone. To develop the techniques of time-resolved crystallography, biomolecules with special properties are required. The Photoactive Yellow Protein is the most sparkling of these.
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Affiliation(s)
- Marius Schmidt
- Physics Department, University of Wisconsin-Milwaukee , 3135 N. Maryland Ave, Milwaukee, Wisconsin 53211, USA
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5
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Coppens P. Perspective: On the relevance of slower-than-femtosecond time scales in chemical structural-dynamics studies. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2015; 2:020901. [PMID: 26798788 PMCID: PMC4711614 DOI: 10.1063/1.4913362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/09/2015] [Indexed: 05/17/2023]
Abstract
A number of examples illustrate structural-dynamics studies of picosecond and slower photo-induced processes. They include molecular rearrangements and excitations. The information that can be obtained from such studies is discussed. The results are complementary to the information obtained from femtosecond studies. The point is made that all pertinent time scales should be covered to obtain comprehensive insight in dynamic processes of chemical and biological importance.
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Affiliation(s)
- Philip Coppens
- Chemistry Department, University at Buffalo , SUNY, Buffalo, New York 14260-3000, USA
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6
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Affiliation(s)
- Majed Chergui
- Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, ISIC, FSB, Station 6, CH-1015 Lausanne, Switzerland.
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7
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Schmidt M, Saldin DK. Enzyme transient state kinetics in crystal and solution from the perspective of a time-resolved crystallographer. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2014; 1:024701. [PMID: 26798774 PMCID: PMC4711602 DOI: 10.1063/1.4869472] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/13/2014] [Indexed: 05/29/2023]
Abstract
With recent technological advances at synchrotrons [Graber et al., J. Synchrotron Radiat. 18, 658-670 (2011)], it is feasible to rapidly collect time-resolved crystallographic data at multiple temperature settings [Schmidt et al., Acta Crystallogr. D 69, 2534-2542 (2013)], from which barriers of activation can be extracted. With the advent of fourth generation X-ray sources, new opportunities emerge to investigate structure and dynamics of biological macromolecules in real time [M. Schmidt, Adv. Condens. Matter Phys. 2013, 1-10] in crystals and potentially from single molecules in random orientation in solution [Poon et al., Adv. Condens. Matter Phys. 2013, 750371]. Kinetic data from time-resolved experiments on short time-scales must be interpreted in terms of chemical kinetics [Steinfeld et al., Chemical Kinetics and Dynamics, 2nd ed. (Prentience Hall, 1985)] and tied to existing time-resolved experiments on longer time-scales [Schmidt et al., Acta Crystallogr. D 69, 2534-2542 (2013); Jung et al., Nat. Chem. 5, 212-220 (2013)]. With this article, we will review and outline steps that are required to routinely determine the energetics of reactions in biomolecules in crystal and solution with newest X-ray sources. In eight sections, we aim to describe concepts and experimental details that may help to inspire new approaches to collect and interpret these data.
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Affiliation(s)
- Marius Schmidt
- Physics Department, University of Wisconsin , Milwaukee, Wisconsin 53211, USA
| | - Dilano K Saldin
- Physics Department, University of Wisconsin , Milwaukee, Wisconsin 53211, USA
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8
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Nath NK, Manoj K, Gâz AŞ, Naumov P. Visible-Light-Induced Photodimerization of a Photoactive Yellow Protein (PYP) Chromophore Model in a Single Crystal. Chemistry 2013; 19:8094-9. [DOI: 10.1002/chem.201300427] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Indexed: 11/06/2022]
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9
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Kalinowski JA, Fournier B, Makal A, Coppens P. The LaueUtil toolkit for Laue photocrystallography. II. Spot finding and integration. JOURNAL OF SYNCHROTRON RADIATION 2012; 19:637-646. [PMID: 22713901 PMCID: PMC3380659 DOI: 10.1107/s0909049512022637] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 05/18/2012] [Indexed: 06/01/2023]
Abstract
A spot-integration method is described which does not require prior indexing of the reflections. It is based on statistical analysis of the values from each of the pixels on successive frames, followed for each frame by morphological analysis to identify clusters of high value pixels which form an appropriate mask corresponding to a reflection peak. The method does not require prior assumptions such as fitting of a profile or definition of an integration box. The results are compared with those of the seed-skewness method which is based on minimizing the skewness of the intensity distribution within a peak's integration box. Applications in Laue photocrystallography are presented.
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Affiliation(s)
- Jarosław A. Kalinowski
- Chemistry Department, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Bertrand Fournier
- Chemistry Department, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA
| | - Anna Makal
- Chemistry Department, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA
| | - Philip Coppens
- Chemistry Department, University at Buffalo, State University of New York, Buffalo, NY 14260-3000, USA
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Schmidt M, Šrajer V, Purwar N, Tripathi S. The kinetic dose limit in room-temperature time-resolved macromolecular crystallography. JOURNAL OF SYNCHROTRON RADIATION 2012; 19:264-73. [PMID: 22338689 PMCID: PMC3284346 DOI: 10.1107/s090904951105549x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 12/23/2011] [Indexed: 05/16/2023]
Abstract
Protein X-ray structures are determined with ionizing radiation that damages the protein at high X-ray doses. As a result, diffraction patterns deteriorate with the increased absorbed dose. Several strategies such as sample freezing or scavenging of X-ray-generated free radicals are currently employed to minimize this damage. However, little is known about how the absorbed X-ray dose affects time-resolved Laue data collected at physiological temperatures where the protein is fully functional in the crystal, and how the kinetic analysis of such data depends on the absorbed dose. Here, direct evidence for the impact of radiation damage on the function of a protein is presented using time-resolved macromolecular crystallography. The effect of radiation damage on the kinetic analysis of time-resolved X-ray data is also explored.
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Affiliation(s)
- M Schmidt
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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11
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Kalinowski JA, Makal A, Coppens P. The LaueUtil toolkit for Laue photocrystallography. I. Rapid orientation matrix determination for intermediate-size-unit-cell Laue data. J Appl Crystallogr 2011; 44:1182-1189. [PMID: 22199400 DOI: 10.1107/s0021889811038143] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 09/18/2011] [Indexed: 11/10/2022] Open
Abstract
A new method for determination of the orientation matrix of Laue X-ray data is presented. The method is based on matching of the experimental patterns of central reciprocal lattice rows projected on a unit sphere centered on the origin of the reciprocal lattice with the corresponding pattern of a monochromatic data set on the same material. This technique is applied to the complete data set and thus eliminates problems often encountered when single frames with a limited number of peaks are to be used for orientation matrix determination. Application of the method to a series of Laue data sets on organometallic crystals is described. The corresponding program is available under a Mozilla Public License-like open-source license.
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12
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Mizuno M, Kamikubo H, Kataoka M, Mizutani Y. Changes in the hydrogen-bond network around the chromophore of photoactive yellow protein in the ground and excited states. J Phys Chem B 2011; 115:9306-10. [PMID: 21688774 DOI: 10.1021/jp2029399] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Changes in the hydrogen-bond (HB) network around the chromophore, p-coumaric acid (pCA), in the ground pG and excited pG* states were investigated for wild type (WT) photoactive yellow protein (PYP) and its mutants using ultraviolet resonance Raman (UVRR) spectroscopy. The intensity depletion of Tyr UVRR bands was observed upon photoexcitation of pCA to the pG* state. The spectral change was ascribed to strengthening of HB between pCA and Tyr42. Comparison of Raman intensities indicated that, in the pG state, the HB between pCA and Tyr42 in WT is a short HB, which is weaker than that in E46Q mutant. In the pG* state, the HB network around pCA of WT is similar to that of E46Q mutant. The present results demonstrate that the HB between pCA and Tyr42 and that between pCA and Glu46 are correlated with each other in the HB network.
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Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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Graber T, Anderson S, Brewer H, Chen YS, Cho HS, Dashdorj N, Henning RW, Kosheleva I, Macha G, Meron M, Pahl R, Ren Z, Ruan S, Schotte F, Srajer V, Viccaro PJ, Westferro F, Anfinrud P, Moffat K. BioCARS: a synchrotron resource for time-resolved X-ray science. JOURNAL OF SYNCHROTRON RADIATION 2011; 18:658-70. [PMID: 21685684 PMCID: PMC3121234 DOI: 10.1107/s0909049511009423] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 03/11/2011] [Indexed: 05/02/2023]
Abstract
BioCARS, a NIH-supported national user facility for macromolecular time-resolved X-ray crystallography at the Advanced Photon Source (APS), has recently completed commissioning of an upgraded undulator-based beamline optimized for single-shot laser-pump X-ray-probe measurements with time resolution as short as 100 ps. The source consists of two in-line undulators with periods of 23 and 27 mm that together provide high-flux pink-beam capability at 12 keV as well as first-harmonic coverage from 6.8 to 19 keV. A high-heat-load chopper reduces the average power load on downstream components, thereby preserving the surface figure of a Kirkpatrick-Baez mirror system capable of focusing the X-ray beam to a spot size of 90 µm horizontal by 20 µm vertical. A high-speed chopper isolates single X-ray pulses at 1 kHz in both hybrid and 24-bunch modes of the APS storage ring. In hybrid mode each isolated X-ray pulse delivers up to ~4 × 10(10) photons to the sample, thereby achieving a time-averaged flux approaching that of fourth-generation X-FEL sources. A new high-power picosecond laser system delivers pulses tunable over the wavelength range 450-2000 nm. These pulses are synchronized to the storage-ring RF clock with long-term stability better than 10 ps RMS. Monochromatic experimental capability with Biosafety Level 3 certification has been retained.
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Affiliation(s)
- T Graber
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, IL 60637, USA.
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Kostov KS, Moffat K. Cluster analysis of time-dependent crystallographic data: Direct identification of time-independent structural intermediates. Biophys J 2011; 100:440-9. [PMID: 21244840 DOI: 10.1016/j.bpj.2010.10.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2010] [Revised: 10/15/2010] [Accepted: 10/19/2010] [Indexed: 10/18/2022] Open
Abstract
The initial output of a time-resolved macromolecular crystallography experiment is a time-dependent series of difference electron density maps that displays the time-dependent changes in underlying structure as a reaction progresses. The goal is to interpret such data in terms of a small number of crystallographically refinable, time-independent structures, each associated with a reaction intermediate; to establish the pathways and rate coefficients by which these intermediates interconvert; and thereby to elucidate a chemical kinetic mechanism. One strategy toward achieving this goal is to use cluster analysis, a statistical method that groups objects based on their similarity. If the difference electron density at a particular voxel in the time-dependent difference electron density (TDED) maps is sensitive to the presence of one and only one intermediate, then its temporal evolution will exactly parallel the concentration profile of that intermediate with time. The rationale is therefore to cluster voxels with respect to the shapes of their TDEDs, so that each group or cluster of voxels corresponds to one structural intermediate. Clusters of voxels whose TDEDs reflect the presence of two or more specific intermediates can also be identified. From such groupings one can then infer the number of intermediates, obtain their time-independent difference density characteristics, and refine the structure of each intermediate. We review the principles of cluster analysis and clustering algorithms in a crystallographic context, and describe the application of the method to simulated and experimental time-resolved crystallographic data for the photocycle of photoactive yellow protein.
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Affiliation(s)
- Konstantin S Kostov
- Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Illinois, USA.
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15
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Westenhoff S, Nazarenko E, Malmerberg E, Davidsson J, Katona G, Neutze R. Time-resolved structural studies of protein reaction dynamics: a smorgasbord of X-ray approaches. Acta Crystallogr A 2010; 66:207-19. [PMID: 20164644 PMCID: PMC2824530 DOI: 10.1107/s0108767309054361] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 12/16/2009] [Indexed: 11/26/2022] Open
Abstract
Time-resolved structural studies of proteins have undergone several significant developments during the last decade. Recent developments using time-resolved X-ray methods, such as time-resolved Laue diffraction, low-temperature intermediate trapping, time-resolved wide-angle X-ray scattering and time-resolved X-ray absorption spectroscopy, are reviewed. Proteins undergo conformational changes during their biological function. As such, a high-resolution structure of a protein’s resting conformation provides a starting point for elucidating its reaction mechanism, but provides no direct information concerning the protein’s conformational dynamics. Several X-ray methods have been developed to elucidate those conformational changes that occur during a protein’s reaction, including time-resolved Laue diffraction and intermediate trapping studies on three-dimensional protein crystals, and time-resolved wide-angle X-ray scattering and X-ray absorption studies on proteins in the solution phase. This review emphasizes the scope and limitations of these complementary experimental approaches when seeking to understand protein conformational dynamics. These methods are illustrated using a limited set of examples including myoglobin and haemoglobin in complex with carbon monoxide, the simple light-driven proton pump bacteriorhodopsin, and the superoxide scavenger superoxide reductase. In conclusion, likely future developments of these methods at synchrotron X-ray sources and the potential impact of emerging X-ray free-electron laser facilities are speculated upon.
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Affiliation(s)
- Sebastian Westenhoff
- Department of Chemistry, Biochemistry and Biophysics, University of Gothenburg, Box 462, SE-40530 Gothenburg, Sweden
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16
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Losi A, Gensch T, van der Horst MA, Hellingwerf KJ, Braslavsky SE. Hydrogen-bond network probed by time-resolved optoacoustic spectroscopy: photoactive yellow protein and the effect of E46Q and E46A mutations. Phys Chem Chem Phys 2009; 7:2229-36. [PMID: 19791418 DOI: 10.1039/b419079c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enthalpy and structural volume changes (delta Hi and delta Vi) produced upon photoinduced formation and decay of the red-shifted intermediate (pR = I1) in the photoactive yellow protein (WT-PYP) from Halorhodospira halophila and the mutated E46Q-PYP and E46A-PYP, were determined by laser-induced optoacoustic spectroscopy (LIOAS) using the two-temperatures method, at pH 8.5. These mutations alter the hydrogen bond between the phenolate oxygen of the chromophore and the residue at position 46. Hydrogen bonding is still possible in E46Q-PYP via the delta-NH2 group of glutamine, whereas it is no longer possible with the methyl group of alanine in E46A-PYP. In all three proteins, pR decays within hundreds of ns to micros into the next intermediate, pR'. The delta H values for the formation of pR (delta H pR) and for its decay into pR'(delta H pR-->pR') are negligibly affected by the E46Q and the E46A substitution. In all three proteins the large delta H pR value drives the photocycle. Whereas delta V pR is a similar contraction of ca. 15 ml mol(-1) for E46Q-PYP and WT-PYP, attributed to strengthening the hydrogen bond network (between 4 and 5 hydrogen bonds) inside the protein chromophore cavity, an expansion is observed for E46A-PYP, indicating just an enlargement of the chromophore cavity upon chromophore isomerization. The results are discussed in the light of the recent time-resolved room temperature, crystallographic studies with WT-PYP and E46Q-PYP. Formation of pR' is somewhat slower for E46Q-PYP and much slower for E46A-PYP. The structural volume change for this transition, delta V pR-->pR', is relatively small and positive for WT-PYP, slightly larger for E46Q-PYP, and definitely larger for the hydrogen-bond lacking E46A-PYP. This indicates a larger entropic change for this transition in E46A-PYP, reflected in the large pre-exponential factor for the pR to pR' decay rate constant determined in the 5-30 degrees C temperature range. This decay also shows an activation entropy that compensates the larger activation energy in E46A-PYP, as compared to the values for WT-PYP and E46Q-PYP.
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Affiliation(s)
- Aba Losi
- Max-Planck-Institut für Bioanorganische Chemie (formerly Strahlenchemie), Postfach 101365, D-45413 Mülheim an der Ruhr, Germany
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Specht A, Bolze F, Omran Z, Nicoud JF, Goeldner M. Photochemical tools to study dynamic biological processes. HFSP JOURNAL 2009; 3:255-64. [PMID: 20119482 PMCID: PMC2799987 DOI: 10.2976/1.3132954] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 04/21/2009] [Indexed: 11/19/2022]
Abstract
Light-responsive biologically active compounds offer the possibility to study the dynamics of biological processes. Phototriggers and photoswitches have been designed, providing the capability to rapidly cause the initiation of wide range of dynamic biological phenomena. We will discuss, in this article, recent developments in the field of light-triggered chemical tools, specially how two-photon excitation, "caged" fluorophores, and the photoregulation of protein activities in combination with time-resolved x-ray techniques should break new grounds in the understanding of dynamic biological processes.
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Affiliation(s)
- Alexandre Specht
- Laboratoire de Conception et Application de Molécules Bioactives, Faculté de Pharmacie, UMR 7199, Université de Strasbourg-CNRS, 74 route du Rhin, F-67401 Illkirch-Graffenstaden Cedex, France
| | - Frédéric Bolze
- Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, UMR 7213, Université de Strasbourg-CNRS, 74 route du Rhin, F-67401 Illkirch-Graffenstaden Cedex, France
| | - Ziad Omran
- Laboratoire de Conception et Application de Molécules Bioactives, Faculté de Pharmacie, UMR 7199, Université de Strasbourg-CNRS, 74 route du Rhin, F-67401 Illkirch-Graffenstaden Cedex, France
| | - Jean-François Nicoud
- Laboratoire de Biophotonique et Pharmacologie, Faculté de Pharmacie, UMR 7213, Université de Strasbourg-CNRS, 74 route du Rhin, F-67401 Illkirch-Graffenstaden Cedex, France
| | - Maurice Goeldner
- Laboratoire de Conception et Application de Molécules Bioactives, Faculté de Pharmacie, UMR 7199, Université de Strasbourg-CNRS, 74 route du Rhin, F-67401 Illkirch-Graffenstaden Cedex, France
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Warren M, Brayshaw S, Johnson A, Schiffers S, Raithby P, Easun T, George M, Warren J, Teat S. Reversible 100 % Linkage Isomerization in a Single-Crystal to Single-Crystal Transformation: Photocrystallographic Identification of the Metastable [Ni(dppe)(η1-ONO)Cl] Isomer. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200901706] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Warren M, Brayshaw S, Johnson A, Schiffers S, Raithby P, Easun T, George M, Warren J, Teat S. Reversible 100 % Linkage Isomerization in a Single-Crystal to Single-Crystal Transformation: Photocrystallographic Identification of the Metastable [Ni(dppe)(η1-ONO)Cl] Isomer. Angew Chem Int Ed Engl 2009; 48:5711-4. [DOI: 10.1002/anie.200901706] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Combining X-ray crystallography and single-crystal spectroscopy to probe enzyme mechanisms. Biochem Soc Trans 2009; 37:378-81. [DOI: 10.1042/bst0370378] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The combination of X-ray crystallography and rapid cryo-trapping methods has enabled the visualization of catalytic intermediates in a variety of enzyme systems. However, the resolution of the X-ray experiment is not always sufficient to precisely place the structure on the reaction pathway. In addition, many trapped intermediates are X-ray-sensitive and can decay during diffraction data collection, resulting in a final structure that may not be representative of the initial trapped species. Complementary methods, such as single-crystal spectroscopy, provide a means to precisely identify the cryo-trapped species as well as detect any X-ray-induced changes during diffraction data collection.
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21
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Hendriks J, Hellingwerf KJ. pH Dependence of the Photoactive Yellow Protein Photocycle Recovery Reaction Reveals a New Late Photocycle Intermediate with a Deprotonated Chromophore. J Biol Chem 2009; 284:5277-88. [DOI: 10.1074/jbc.m805904200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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22
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Philip AF, Eisenman KT, Papadantonakis GA, Hoff WD. Functional tuning of photoactive yellow protein by active site residue 46. Biochemistry 2009; 47:13800-10. [PMID: 19102703 DOI: 10.1021/bi801730y] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein-ligand interactions alter the properties of active site groups to achieve specific biological functions. The active site of photoactive yellow protein (PYP) provides a model system for studying such functional tuning. PYP is a small bacterial photoreceptor with photochemistry based on its p-coumaric acid (pCA) chromophore. The absorbance maximum and pK(a) of the pCA in the active site of native PYP are shifted from 400 nm and 8.8 in water to 446 nm and 2.8 in the native protein milieu, respectively, by protein-ligand interactions. We report high-throughput microscale methods for the purification and spectroscopic investigation of PYP and use these to examine the role of active site residue Glu46 in PYP, which is hydrogen bonded to the pCA anion. The functional and structural attributes of the 19 substitution mutants of PYP at critical active site position 46 vary widely, with absorbance maxima from 441 to 478 nm, pCA fluorescence quantum yields from 0.19 to 1.4%, pCA pK(a) values from 3.0 to 9.0, and protein folding stabilities from 6.5 to 12.9 kcal/mol. The kinetics of the last photocycle transition vary by more than 4 orders of magnitude and are often strongly biphasic. Only E46Q PYP exhibits a greatly accelerated photocycling rate. All substitutions yield a folded, photoactive PYP, illustrating the robustness of protein structure and function. Correlations between side chain and mutant properties establish the importance of residue 46 in tuning the function of PYP and the significance of the strength of its hydrogen bond to the pCA. Native PYP exhibits the lowest values for pCA fluorescence quantum yield and pK(a), indicating their functional relevance. These results demonstrate the value of quantitative high-throughput biophysical studies of proteins.
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Affiliation(s)
- Andrew F Philip
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA
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23
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Chergui M, Zewail AH. Electron and X-Ray Methods of Ultrafast Structural Dynamics: Advances and Applications. Chemphyschem 2009; 10:28-43. [DOI: 10.1002/cphc.200800667] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Abstract
Heme proteins, with their natural photosensitivity, are excellent systems for the application of time-resolved crystallographic methods. Ligand dissociation can be readily initiated by a short laser pulse with global structural changes probed at the atomic level by X-rays in real time. Third-generation synchrotrons provide 100-ps X-ray pulses of sufficient intensity for monitoring very fast processes. Successful application of such time-resolved crystallographic experiments requires that the structural changes being monitored are compatible with the crystal lattice. These techniques have recently permitted observing for the first time allosteric transitions in real time for a cooperative dimeric hemoglobin.
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Affiliation(s)
- Vukica Srajer
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois, USA
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25
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Anderson S, Šrajer V, Moffat K. Structural Heterogeneity of Cryotrapped Intermediates in the Bacterial Blue Light Photoreceptor, Photoactive Yellow Protein¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2004.tb00042.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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26
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Leenders EJM, Guidoni L, Röthlisberger U, Vreede J, Bolhuis PG, Meijer EJ. Protonation of the chromophore in the photoactive yellow protein. J Phys Chem B 2007; 111:3765-73. [PMID: 17388542 DOI: 10.1021/jp067158b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The photoactive yellow protein (PYP) acts as a light sensor to its bacterial host: it responds to light by changing shape. After excitation by blue light, PYP undergoes several transformations, to partially unfold into its signaling state. One of the crucial steps in this photocycle is the protonation of p-coumaric acid after excitation and isomerization of this chromophore. Experimentalists still debate on the nature of the proton donor and on whether it donates the hydrogen directly or indirectly. To obtain better knowledge of the mechanism, we studied this proton transfer using Car-Parrinello molecular dynamics, classical molecular dynamics, and computer simulations combining these two methods (quantum mechanics/molecular mechanics, QMMM). The simulations reproduce the chromophore structure and hydrogen-bond network of the protein measured by X-ray crystallography and NMR. When the chromophore is protonated, it leaves the assumed proton donor, glutamic acid 46, with a negative charge in a hydrophobic environment. We show that the stabilization of this charge is a very important factor in the mechanism of protonation. Protonation frequently occurs in simplified ab initio simulations of the chromophore binding pocket in vacuum, where amino acids can easily hydrogen bond to Glu46. When the complete protein environment is incorporated in a QMMM simulation on the complete protein, no proton transfer is observed within 14 ps. The hydrogen-bond rearrangements in this time span are not sufficient to stabilize the new protonation state. Force field molecular dynamics simulations on a much longer time scale have shown which internal rearrangements of the protein are needed. Combining these simulations with more QMMM calculations enabled us to check the stability of protonation states and clarify the initial requirements for the proton transfer in PYP.
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Affiliation(s)
- Elske J M Leenders
- Van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
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Brudler R, Gessner CR, Li S, Tyndall S, Getzoff ED, Woods VL. PAS domain allostery and light-induced conformational changes in photoactive yellow protein upon I2 intermediate formation, probed with enhanced hydrogen/deuterium exchange mass spectrometry. J Mol Biol 2006; 363:148-60. [PMID: 16952373 PMCID: PMC2575420 DOI: 10.1016/j.jmb.2006.07.078] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 07/24/2006] [Accepted: 07/28/2006] [Indexed: 11/21/2022]
Abstract
Photoactive yellow protein (PYP) is a small bacterial photoreceptor that undergoes a light-activated reaction cycle. PYP is also the prototypical Per-Arnt-Sim (PAS) domain. PAS domains, found in diverse multi-domain proteins from bacteria to humans, mediate protein-protein interactions and function as sensors and signal transducers. Here, we investigate conformational and dynamic changes in solution in wild-type PYP upon formation of the long-lived putative signaling intermediate I2 with enhanced hydrogen/deuterium exchange mass spectrometry (DXMS). The DXMS results showed that the central beta-sheet remains stable but specific external protein segments become strongly deprotected. Light-induced disruption of the dark-state hydrogen bonding network in I2 produces increased flexibility and opening of PAS core helices alpha3 and alpha4, releases the beta4-beta5 hairpin, and propagates conformational changes to the central beta-sheet. Surprisingly, the first approximately 10 N-terminal residues, which are essential for fast dark-state recovery from I2, become more protected. By combining the DXMS results with our crystallographic structures, which reveal detailed changes near the chromophore but limited protein conformational change, we propose a mechanism for I2 state formation. This mechanism integrates the results from diverse biophysical studies of PYP, and links an allosteric T to R-state conformational transition to three pathways for signal propagation within the PYP fold. On the basis of the observed changes in PYP plus commonalities shared among PAS domain proteins, we further propose that PAS domains share this conformational mechanism, which explains the versatile signal transduction properties of the structurally conserved PYP/PAS module by framework-encoded allostery.
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Affiliation(s)
- Ronald Brudler
- Department of Molecular Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Chris R. Gessner
- Department of Medicine and Biomedical Sciences Graduate Program, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Sheng Li
- Department of Medicine and Biomedical Sciences Graduate Program, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Sammy Tyndall
- Department of Medicine and Biomedical Sciences Graduate Program, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Elizabeth D. Getzoff
- Department of Molecular Biology and Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Virgil L. Woods
- Department of Medicine and Biomedical Sciences Graduate Program, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
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28
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Baxter RHG, Krausz E, Norris JR. Photoactivation of the photosynthetic reaction center of Blastochloris viridis in the crystalline state. J Phys Chem B 2006; 110:1026-32. [PMID: 16471638 DOI: 10.1021/jp053697p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photoactivation in crystals of the bacterial reaction center of Blastochloris viridis was investigated by near-infrared spectroscopy. The bleaching of the special pair absorption at 970 nm and the simultaneous rise of the special pair cation absorption at 1300 nm were measured in response to transient irradiation by a HeNe laser over 5 orders of magnitude in laser power. The resulting power-saturation curve can be used to estimate the true extent of photoactivation achieved in a prior time-resolved crystallographic experiment (Baxter et al. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 5982-5987). The overall extent of photoactivation was 50%, which demonstrates that the time-resolved crystallographic method can be applied to the optically dense reaction center crystals. Measurement of the charge-recombination rate, however, suggests the presence of a long-lived P+ state within the crystal.
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Affiliation(s)
- Richard H G Baxter
- Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, USA.
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29
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Yeremenko S, van Stokkum IHM, Moffat K, Hellingwerf KJ. Influence of the crystalline state on photoinduced dynamics of photoactive yellow protein studied by ultraviolet-visible transient absorption spectroscopy. Biophys J 2006; 90:4224-35. [PMID: 16513787 PMCID: PMC1459521 DOI: 10.1529/biophysj.105.074765] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Time-resolved ultraviolet-visible spectroscopy was used to characterize the photocycle transitions in single crystals of wild-type and the E-46Q mutant of photoactive yellow protein (PYP) with microsecond time resolution. The results were compared with the results of similar measurements on aqueous solutions of these two variants of PYP, with and without the components present in the mother liquor of crystals. The experimental data were analyzed with global and target analysis. Distinct differences in the reaction path of a PYP molecule are observed between these conditions when it progresses through its photocycle. In the crystalline state i), much faster relaxation of the late blue-shifted photocycle intermediate back to the ground state is observed; ii), this intermediate in crystalline PYP absorbs at 380 nm, rather than at 350-360 nm in solution; and iii), for various intermediates of this photocycle the forward reaction through the photocycle directly competes with a branching reaction that leads directly to the ground state. Significantly, with these altered characteristics, the spectroscopic data on PYP are fully consistent with the structural data obtained for this photoreceptor protein with time-resolved x-ray diffraction analysis, particularly for wild-type PYP.
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Affiliation(s)
- Sergey Yeremenko
- Laboratory for Microbiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, NL-1018 WV Amsterdam, The Netherlands
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30
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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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31
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Shimizu N, Imamoto Y, Harigai M, Kamikubo H, Yamazaki Y, Kataoka M. pH-dependent Equilibrium between Long Lived Near-UV Intermediates of Photoactive Yellow Protein. J Biol Chem 2006; 281:4318-25. [PMID: 16368695 DOI: 10.1074/jbc.m506403200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The long lived intermediate (signaling state) of photoactive yellow protein (PYP(M)), which is formed in the photocycle, was characterized at various pHs. PYP(M) at neutral pH was in equilibrium between two spectroscopically distinct states. Absorption maxima of the acidic form (PYP(M)(acid)) and alkaline form (PYP(M)(alkali)) were located at 367 and 356 nm, respectively. Equilibrium was represented by the Henderson-Hasselbalch equation, in which apparent pK(a) was 6.4. Content of alpha- and/or beta-structure of PYP(M)(acid) was significantly greater than PYP(M)(alkali) as demonstrated by the molar ellipticity at 222 nm. In addition, changes in amide I and II modes of beta-structure in the difference Fourier transform infrared spectra for formation of PYP(M)(acid) was smaller than that of PYP(M)(alkali). The vibrational mode at 1747 cm(-1) of protonated Glu-46 was found as a small band for PYP(M)(acid) but not for PYP(M)(alkali), suggesting that Glu-46 remains partially protonated in PYP(M)(acid), whereas it is fully deprotonated in PYP(M)(alkali). Small angle x-ray scattering measurements demonstrated that the radius of gyration of PYP(M)(acid) was 15.7 Angstroms, whereas for PYP(M)(alkali) it was 16.2 Angstroms. These results indicate that PYP(M)(acid) assumes a more ordered and compact structure than PYP(M)(alkali). Binding of citrate shifts this equilibrium toward PYP(M)(alkali). UV-visible absorption spectra and difference infrared spectra of the long lived intermediate formed from E46Q mutant was consistent with those of PYP(M)(acid), indicating that the mutation shifts this equilibrium toward PYP(M)(acid). Alterations in the nature of PYP(M) by pH, citrate, and mutation of Glu-46 are consistently explained by the shift of the equilibrium between PYP(M)(acid) and PYP(M)(alkali).
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Affiliation(s)
- Nobutaka Shimizu
- Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Japan
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32
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Coppens P, Zheng SL, Gembicky M, Messerschmidt M, Dominiak PM. Supramolecular solids and time-resolved diffraction. CrystEngComm 2006. [DOI: 10.1039/b610286g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Schmidt M, Nienhaus K, Pahl R, Krasselt A, Anderson S, Parak F, Nienhaus GU, Srajer V. Ligand migration pathway and protein dynamics in myoglobin: a time-resolved crystallographic study on L29W MbCO. Proc Natl Acad Sci U S A 2005; 102:11704-9. [PMID: 16085709 PMCID: PMC1187994 DOI: 10.1073/pnas.0504932102] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
By using time-resolved x-ray crystallography at room temperature, structural relaxations and ligand migration were examined in myoglobin (Mb) mutant L29W from nanoseconds to seconds after photodissociation of carbon monoxide (CO) from the heme iron by nanosecond laser pulses. The data were analyzed in terms of transient kinetics by fitting trial functions to integrated difference electron density values obtained from select structural moieties, thus allowing a quantitative description of the processes involved. The observed relaxations are linked to other investigations on protein dynamics. At the earliest times, the heme has already completely relaxed into its domed deoxy structure, and there is no photo-dissociated CO visible at the primary docking site. Initial relaxations of larger globin moieties are completed within several hundred nanoseconds. They influence the concomitant migration of photo-dissociated CO to the Xe1 site, where it appears at approximately 300 ns and leaves again at approximately 1.5 ms. The extremely long residence time in Xe1 as compared with wild-type MbCO implies that, in the latter protein, the CO exits the protein from Xe1 predominantly via the distal pocket. A well-defined deligated state is populated between approximately 2 micros and approximately 1 ms; its structure is very similar to the equilibrium deoxy structure. Between 1.5 and 20 ms, no CO is visible in the protein interior; it is either distributed among many sites within the protein or has escaped to the solvent. Finally, recombination at the heme iron occurs after >20 ms.
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Affiliation(s)
- Marius Schmidt
- Physikdepartment E17, Technische Universität München, James Franck Strasse, 85747 Garching, Germany.
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Rajagopal S, Anderson S, Srajer V, Schmidt M, Pahl R, Moffat K. A structural pathway for signaling in the E46Q mutant of photoactive yellow protein. Structure 2005; 13:55-63. [PMID: 15642261 DOI: 10.1016/j.str.2004.10.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Revised: 10/21/2004] [Accepted: 10/21/2004] [Indexed: 11/22/2022]
Abstract
In the bacterial photoreceptor photoactive yellow protein (PYP), absorption of blue light by its chromophore leads to a conformational change in the protein associated with differential signaling activity, as it executes a reversible photocycle. Time-resolved Laue crystallography allows structural snapshots (as short as 150 ps) of high crystallographic resolution (approximately 1.6 A) to be taken of a protein as it functions. Here, we analyze by singular value decomposition a comprehensive time-resolved crystallographic data set of the E46Q mutant of PYP throughout the photocycle spanning 10 ns-100 ms. We identify and refine the structures of five distinct intermediates and provide a plausible chemical kinetic mechanism for their inter conversion. A clear structural progression is visible in these intermediates, in which a signal generated at the chromophore propagates through a distinct structural pathway of conserved residues and results in structural changes near the N terminus, over 20 A distant from the chromophore.
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Affiliation(s)
- Sudarshan Rajagopal
- Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA
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Ihee H, Rajagopal S, Srajer V, Pahl R, Anderson S, Schmidt M, Schotte F, Anfinrud PA, Wulff M, Moffat K. Visualizing reaction pathways in photoactive yellow protein from nanoseconds to seconds. Proc Natl Acad Sci U S A 2005; 102:7145-50. [PMID: 15870207 PMCID: PMC1088170 DOI: 10.1073/pnas.0409035102] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Indexed: 11/18/2022] Open
Abstract
Determining 3D intermediate structures during the biological action of proteins in real time under ambient conditions is essential for understanding how proteins function. Here we use time-resolved Laue crystallography to extract short-lived intermediate structures and thereby unveil signal transduction in the blue light photoreceptor photoactive yellow protein (PYP) from Halorhodospira halophila. By analyzing a comprehensive set of Laue data during the PYP photocycle (forty-seven time points from one nanosecond to one second), we track all atoms in PYP during its photocycle and directly observe how absorption of a blue light photon by its p-coumaric acid chromophore triggers a reversible photocycle. We identify a complex chemical mechanism characterized by five distinct structural intermediates. Structural changes at the chromophore in the early, red-shifted intermediates are transduced to the exterior of the protein in the late, blue-shifted intermediates through an initial "volume-conserving" isomerization of the chromophore and the progressive disruption of hydrogen bonds between the chromophore and its surrounding binding pocket. These results yield a comprehensive view of the PYP photocycle when seen in the light of previous biophysical studies on the system.
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Affiliation(s)
- Hyotcherl Ihee
- Department of Chemistry and School of Molecular Science (BK21), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, South Korea.
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Abstract
The PAS (Per-ARNT-Sim) superfamily is presented as a well-suited study case to demonstrate how comparison of functional motions among distant homologous proteins with conserved fold characteristics may give insight into their functional specialization. Based on the importance of structural flexibility of the receptive structures in anticipating the signal-induced conformational changes of these sensory systems, the dynamics of these structures were analysed. Molecular dynamics was proved to be an effective method to obtain a reliable picture of the dynamics of the crystal structures of HERG, phy3, PYP and FixL, provided that an extensive conformational space sampling is performed. Other reliable sources of dynamic information were the ensembles of NMR structures of hPASK, HIF-2alpha and PYP. Essential dynamics analysis was successfully employed to extract the relevant information from the sampled conformational spaces. Comparison of motion patterns in the essential subspaces, based on the structural alignment, allowed identification of the specialized region in each domain. This appears to be evolved in the superfamily by following a specific trend, that also suggests the presence of a limited number of general solutions adopted by the PAS domains to sense external signals. These findings may give insight into unknown mechanisms of PAS domains and guide further experimental studies.
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Affiliation(s)
- A Pandini
- Dipartimento di Scienze dell'Ambiente e del Territorio, Università degli Studi di Milano-Bicocca, Piazza della Scienza 1, 20126 Milan, Italy
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van der Horst MA, Laan W, Yeremenko S, Wende A, Palm P, Oesterhelt D, Hellingwerf KJ. From primary photochemistry to biological function in the blue-light photoreceptors PYP and AppA. Photochem Photobiol Sci 2005; 4:688-93. [PMID: 16121278 DOI: 10.1039/b418442b] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To properly respond to changes in fluency conditions, Nature has developed a variety of photosensors that modulate gene expression, enzyme activity and/or motility. Dedicated types have evolved, which can be classified in six families: rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins and BLUF-proteins. The photochemistry of the first three families is based on cis/trans isomerization of an ethylene bond. Surprisingly, the latter three all use flavin as their chromophore, but each with very different photochemistry. In this contribution we will discuss the molecular basis of signal generation in a xanthopsin (Photoactive Yellow Protein (PYP) from Halorhodospira halophila), a photoreceptor for negative phototaxis, and in a BLUF protein (AppA from Rhodobacter sphaeroides), a transcriptional anti-repressor. PYP is activated through trans/cis isomerization of the 7,8-vinyl bond of its 4-hydroxycinnamic acid chromophore. This initiates a photocycle with multiple intermediates, like pB, which is formed after intramolecular proton transfer. The negative charge thus formed in the interior of the protein triggers formation of a partially unfolded signaling state. For AppA much less is known about the underlying photochemistry. Available evidence suggests that it is based on a light-induced change in the hydrogen-bonding of its flavin chromophore and/or a change in hydrophobic stacking between the flavin and/or nearby aromatic amino acids like Y 21. A signaling state is formed within microseconds, which recovers with a rate of approximately 10(-3) s(-1). The change in conformation between receptor- and signaling-state in AppA, however, appear to be minute as compared to those in PYP. Here we review the underlying chemistry in the various steps of the photocycle of these two photoreceptor proteins and provide new data on their mechanism and function.
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Affiliation(s)
- M A van der Horst
- Laboratory for Microbiology, Swammerdam Institute for Life Sciences, Nieuwe Achtergracht 166, NL-1018WV Amsterdam, The Netherlands
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Vreede J, Crielaard W, Hellingwerf KJ, Bolhuis PG. Predicting the signaling state of photoactive yellow protein. Biophys J 2005; 88:3525-35. [PMID: 15722437 PMCID: PMC1305499 DOI: 10.1529/biophysj.104.055103] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As a bacterial blue light sensor the photoactive yellow protein (PYP) undergoes conformational changes upon signal transduction. The absorption of a photon triggers a series of events that are initially localized around the protein chromophore, extends to encompass the whole protein within microseconds, and leads to the formation of the transient pB signaling state. We study the formation of this signaling state pB by molecular simulation and predict its solution structure. Conventional straightforward molecular dynamics is not able to address this formation process due to the long (microsecond) timescales involved, which are (partially) caused by the presence of free energy barriers between the metastable states. To overcome these barriers, we employed the parallel tempering (or replica exchange) method, thus enabling us to predict qualitatively the formation of the PYP signaling state pB. In contrast to the receptor state pG of PYP, the characteristics of this predicted pB structure include a wide open chromophore-binding pocket, with the chromophore and Glu(46) fully solvent-exposed. In addition, loss of alpha-helical structure occurs, caused by the opening motion of the chromophore-binding pocket and the disruptive interaction of the negatively charged Glu(46) with the backbone atoms in the hydrophobic core of the N-terminal cap. Recent NMR experiments agree very well with these predictions.
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Affiliation(s)
- Jocelyne Vreede
- Swammerdam Institute for Life Sciences, and van 't Hoff Institute of Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
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Rajagopal S, Kostov KS, Moffat K. Analytical trapping: extraction of time-independent structures from time-dependent crystallographic data. J Struct Biol 2005; 147:211-22. [PMID: 15450291 DOI: 10.1016/j.jsb.2004.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Revised: 03/05/2004] [Indexed: 11/26/2022]
Abstract
All chemical and biological reactions involve atomic motion, embodied in dynamic structural changes. Identifying these changes is the goal of time-resolved crystallography. The "raw" output of a time-resolved macromolecular crystallography experiment is the time-dependent set of difference electron density maps that span the desired time range and display the time-dependent changes in density (and underlying structure) as the reaction progresses. The goal is to interpret such data in terms of a small number of crystallographically refinable, time-independent structures, each associated with a reaction intermediate; to establish the pathways and rate coefficients by which the intermediates interconvert; and thus to establish a chemical kinetic mechanism. We review briefly the various strategies that may be used to achieve this goal and concentrate on two promising advances: singular value decomposition and cluster analysis. The strategies are illustrated by using data on the photocycle of the bacterial blue light photoreceptor, photoactive yellow protein.
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Affiliation(s)
- Sudarshan Rajagopal
- Department of Biochemistry and Molecular Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA
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Schmidt M, Ihee H, Pahl R, Srajer V. Protein-ligand interaction probed by time-resolved crystallography. Methods Mol Biol 2005; 305:115-54. [PMID: 15939996 DOI: 10.1385/1-59259-912-5:115] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Time-resolved (TR) crystallography is a unique method for determining the structures of intermediates in biomolecular reactions. The technique reached its mature stage with the development of the powerful third-generation synchrotron X-ray sources, and the advances in data processing and analysis of time-resolved Laue crystallographic data. A time resolution of 100 ps has been achieved and relatively small structural changes can be detected even from only partial reaction initiation. The remaining challenge facing the application of this technique to a broad range of biological systems is to find an efficient and rapid, system-specific method for the reaction initiation in the crystal. Other frontiers for the technique involve the continued improvement in time resolution and further advances in methods for determining intermediate structures and reaction mechanisms. The time-resolved technique, combined with trapping methods and computational approaches, holds the promise for a complete structure-based description of biomolecular reactions.
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Affiliation(s)
- Marius Schmidt
- Department of Physics, Technical University of Munich, Garching, Germany
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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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