1
|
Kabir M, Ghosh P, Gozem S. Electronic Structure Methods for Simulating Flavin's Spectroscopy and Photophysics: Comparison of Multi-reference, TD-DFT, and Single-Reference Wave Function Methods. J Phys Chem B 2024; 128:7545-7557. [PMID: 39074870 PMCID: PMC11317985 DOI: 10.1021/acs.jpcb.4c03748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 07/14/2024] [Accepted: 07/22/2024] [Indexed: 07/31/2024]
Abstract
The use of flavins and flavoproteins in photocatalytic, sensing, and biotechnological applications has led to a growing interest in computationally modeling the excited-state electronic structure and photophysics of flavin. However, there is limited consensus regarding which computational methods are appropriate for modeling flavin's photophysics. We compare the energies of low-lying excited states of flavin computed with time-dependent density functional theory (TD-DFT), equation-of-motion coupled cluster (EOM-EE-CCSD), scaled opposite-spin configuration interaction [SOS-CIS(D)], multiconfiguration pair-density functional theory (MC-PDFT), and several multireference perturbation theory (MR-PT2) methods. In the first part, we focus on excitation energies of the first singlet excited state (S1) of five different redox and protonation states of flavin, with the goal of finding a suitable active space for MR-PT2 calculations. In the second part, we construct two sets of one-dimensional potential energy surfaces connecting the S0 and S1 equilibrium geometries (S0-S1 path) and the S1 (π,π*) and S2 (n,π*) equilibrium geometries (S1-S2 path). The first path therefore follows a Franck-Condon active mode of flavin while the second path maps crossings points between low-lying singlet and triplet states in flavin. We discuss the similarities and differences in the TD-DFT, EOM-EE-CCSD, SOS-CIS(D), MC-PDFT and MR-PT2 energy profiles along these paths. We find that (TD-)DFT methods are suitable for applications such as simulating the spectra of flavins but are inconsistent with several other methods when used for some geometry optimizations and when describing the energetics of dark (n,π*) states. MR-PT2 methods show promise for the simulation of flavin's low-lying excited states, but the selection of orbitals for the active space and the number of roots used for state averaging must be done carefully to avoid artifacts. Some properties, such as the intersystem crossing geometry and energy between the S1 (π,π*) and T2 (n,π*) states, may require additional benchmarking before they can be determined quantitatively.
Collapse
Affiliation(s)
- Mohammad
Pabel Kabir
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Paulami Ghosh
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| |
Collapse
|
2
|
Salvadori G, Mazzeo P, Accomasso D, Cupellini L, Mennucci B. Deciphering Photoreceptors Through Atomistic Modeling from Light Absorption to Conformational Response. J Mol Biol 2024; 436:168358. [PMID: 37944793 DOI: 10.1016/j.jmb.2023.168358] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/28/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023]
Abstract
In this review, we discuss the successes and challenges of the atomistic modeling of photoreceptors. Throughout our presentation, we integrate explanations of the primary methodological approaches, ranging from quantum mechanical descriptions to classical enhanced sampling methods, all while providing illustrative examples of their practical application to specific systems. To enhance the effectiveness of our analysis, our primary focus has been directed towards the examination of applications across three distinct photoreceptors. These include an example of Blue Light-Using Flavin (BLUF) domains, a bacteriophytochrome, and the orange carotenoid protein (OCP) employed by cyanobacteria for photoprotection. Particular emphasis will be placed on the pivotal role played by the protein matrix in fine-tuning the initial photochemical event within the embedded chromophore. Furthermore, we will investigate how this localized perturbation initiates a cascade of events propagating from the binding pocket throughout the entire protein structure, thanks to the intricate network of interactions between the chromophore and the protein.
Collapse
Affiliation(s)
- Giacomo Salvadori
- Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy
| | - Patrizia Mazzeo
- Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy
| | - Davide Accomasso
- Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy
| | - Lorenzo Cupellini
- Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy
| | - Benedetta Mennucci
- Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy
| |
Collapse
|
3
|
Hontani Y, Mehlhorn J, Domratcheva T, Beck S, Kloz M, Hegemann P, Mathes T, Kennis JTM. Spectroscopic and Computational Observation of Glutamine Tautomerization in the Blue Light Sensing Using Flavin Domain Photoreaction. J Am Chem Soc 2023; 145:1040-1052. [PMID: 36607126 PMCID: PMC9853863 DOI: 10.1021/jacs.2c10621] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Blue light sensing using flavin (BLUF) domains constitute a family of flavin-binding photoreceptors of bacteria and eukaryotic algae. BLUF photoactivation proceeds via a light-driven hydrogen-bond switch among flavin adenine dinucleotide (FAD) and glutamine and tyrosine side chains, whereby FAD undergoes electron and proton transfer with tyrosine and is subsequently re-oxidized by a hydrogen back-shuttle in picoseconds, constituting an important model system to understand proton-coupled electron transfer in biology. The specific structure of the hydrogen-bond patterns and the prevalence of glutamine tautomeric states in dark-adapted (DA) and light-activated (LA) states have remained controversial. Here, we present a combined femtosecond stimulated Raman spectroscopy (FSRS), computational chemistry, and site-selective isotope labeling Fourier-transform infrared spectroscopy (FTIR) study of the Slr1694 BLUF domain. FSRS showed distinct vibrational bands from the FADS1 singlet excited state. We observed small but significant shifts in the excited-state vibrational frequency patterns of the DA and LA states, indicating that these frequencies constitute a sensitive probe for the hydrogen-bond arrangement around FAD. Excited-state model calculations utilizing four different realizations of hydrogen bond patterns and glutamine tautomeric states were consistent with a BLUF reaction model that involved glutamine tautomerization to imidic acid, accompanied by a rotation of its side chain. A combined FTIR and double-isotope labeling study, with 13C labeling of FAD and 15N labeling of glutamine, identified the glutamine imidic acid C═N stretch vibration in the LA state and the Gln C═O in the DA state. Hence, our study provides support for glutamine tautomerization and side-chain rotation in the BLUF photoreaction.
Collapse
Affiliation(s)
- Yusaku Hontani
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands
| | - Jennifer Mehlhorn
- Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Tatiana Domratcheva
- Department
of Biomolecular Mechanisms, Max Planck Institute
for Medical Research, 69120 Heidelberg, Germany,Department
of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Sebastian Beck
- Department
of Chemistry, Humboldt-Universität
zu Berlin, Brook-Taylor-Str.
2, 12489 Berlin, Germany
| | - Miroslav Kloz
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,Institute
of Physics, ELI-Beamlines, Na Slovance 2, 182
21 Praha 8, Czech Republic
| | - Peter Hegemann
- Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Tilo Mathes
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - John T. M. Kennis
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,
| |
Collapse
|
4
|
Giudetti G, Polyakov I, Grigorenko BL, Faraji S, Nemukhin AV, Krylov AI. How Reproducible Are QM/MM Simulations? Lessons from Computational Studies of the Covalent Inhibition of the SARS-CoV-2 Main Protease by Carmofur. J Chem Theory Comput 2022; 18:5056-5067. [PMID: 35797455 DOI: 10.1021/acs.jctc.2c00286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work explores the level of transparency in reporting the details of computational protocols that is required for practical reproducibility of quantum mechanics/molecular mechanics (QM/MM) simulations. Using the reaction of an essential SARS-CoV-2 enzyme (the main protease) with a covalent inhibitor (carmofur) as a test case of chemical reactions in biomolecules, we carried out QM/MM calculations to determine the structures and energies of the reactants, the product, and the transition state/intermediate using analogous QM/MM models implemented in two software packages, NWChem and Q-Chem. Our main benchmarking goal was to reproduce the key energetics computed with the two packages. Our results indicate that quantitative agreement (within the numerical thresholds used in calculations) is difficult to achieve. We show that rather minor details of QM/MM simulations must be reported in order to ensure the reproducibility of the results and offer suggestions toward developing practical guidelines for reporting the results of biosimulations.
Collapse
Affiliation(s)
- Goran Giudetti
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Igor Polyakov
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Bella L Grigorenko
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Shirin Faraji
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747 AG The Netherlands
| | - Alexander V Nemukhin
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Anna I Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| |
Collapse
|
5
|
Atz K, Isert C, Böcker MNA, Jiménez-Luna J, Schneider G. Δ-Quantum machine-learning for medicinal chemistry. Phys Chem Chem Phys 2022; 24:10775-10783. [PMID: 35470831 PMCID: PMC9093086 DOI: 10.1039/d2cp00834c] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many molecular design tasks benefit from fast and accurate calculations of quantum-mechanical (QM) properties. However, the computational cost of QM methods applied to drug-like molecules currently renders large-scale applications of quantum chemistry challenging. Aiming to mitigate this problem, we developed DelFTa, an open-source toolbox for the prediction of electronic properties of drug-like molecules at the density functional (DFT) level of theory, using Δ-machine-learning. Δ-Learning corrects the prediction error (Δ) of a fast but inaccurate property calculation. DelFTa employs state-of-the-art three-dimensional message-passing neural networks trained on a large dataset of QM properties. It provides access to a wide array of quantum observables on the molecular, atomic and bond levels by predicting approximations to DFT values from a low-cost semiempirical baseline. Δ-Learning outperformed its direct-learning counterpart for most of the considered QM endpoints. The results suggest that predictions for non-covalent intra- and intermolecular interactions can be extrapolated to larger biomolecular systems. The software is fully open-sourced and features documented command-line and Python APIs.
Collapse
Affiliation(s)
- Kenneth Atz
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
| | - Clemens Isert
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
| | - Markus N A Böcker
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
| | - José Jiménez-Luna
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland. .,Department of Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Straße 65, 88397 Biberach an der Riss, Germany
| | - Gisbert Schneider
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland. .,ETH Singapore SEC Ltd., 1 CREATE Way, #06-01 CREATE Tower, Singapore 138602, Singapore
| |
Collapse
|
6
|
Hashem S, Macaluso V, Nottoli M, Lipparini F, Cupellini L, Mennucci B. From crystallographic data to the solution structure of photoreceptors: the case of the AppA BLUF domain. Chem Sci 2021; 12:13331-13342. [PMID: 34777752 PMCID: PMC8528011 DOI: 10.1039/d1sc03000k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/01/2021] [Indexed: 12/28/2022] Open
Abstract
Photoreceptor proteins bind a chromophore, which, upon light absorption, modifies its geometry or its interactions with the protein, finally inducing the structural change needed to switch the protein from an inactive to an active or signaling state. In the Blue Light-Using Flavin (BLUF) family of photoreceptors, the chromophore is a flavin and the changes have been connected with a rearrangement of the hydrogen bond network around it on the basis of spectroscopic changes measured for the dark-to-light conversion. However, the exact conformational change triggered by the photoexcitation is still elusive mainly because a clear consensus on the identity not only of the light activated state but also of the dark one has not been achieved. Here, we present an integrated investigation that combines microsecond MD simulations starting from the two conflicting crystal structures available for the AppA BLUF domain with calculations of NMR, IR and UV-Vis spectra using a polarizable QM/MM approach. Thanks to such a combined analysis of the three different spectroscopic responses, a robust characterization of the structure of the dark state in solution is given together with the uncovering of important flaws of the most popular molecular mechanisms present in the literature for the dark-to-light activation.
Collapse
Affiliation(s)
- Shaima Hashem
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Veronica Macaluso
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Michele Nottoli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Filippo Lipparini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Lorenzo Cupellini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| |
Collapse
|
7
|
Macaluso V, Hashem S, Nottoli M, Lipparini F, Cupellini L, Mennucci B. Ultrafast Transient Infrared Spectroscopy of Photoreceptors with Polarizable QM/MM Dynamics. J Phys Chem B 2021; 125:10282-10292. [PMID: 34476939 PMCID: PMC8450903 DOI: 10.1021/acs.jpcb.1c05753] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/04/2021] [Indexed: 01/02/2023]
Abstract
Ultrafast transient infrared (TRIR) spectroscopy is widely used to measure the excitation-induced structural changes of protein-bound chromophores. Here, we design a novel and general strategy to compute TRIR spectra of photoreceptors by combining μs-long MM molecular dynamics with ps-long QM/AMOEBA Born-Oppenheimer molecular dynamics (BOMD) trajectories for both ground and excited electronic states. As a proof of concept, the strategy is here applied to AppA, a blue-light-utilizing flavin (BLUF) protein, found in bacteria. We first analyzed the short-time evolution of the embedded flavin upon excitation revealing that its dynamic Stokes shift is ultrafast and mainly driven by the internal reorganization of the chromophore. A different normal-mode representation was needed to describe ground- and excited-state IR spectra. In this way, we could assign all of the bands observed in the measured transient spectrum. In particular, we could characterize the flavin isoalloxazine-ring region of the spectrum, for which a full and clear description was missing.
Collapse
Affiliation(s)
| | | | - Michele Nottoli
- Dipartimento di Chimica e
Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Filippo Lipparini
- Dipartimento di Chimica e
Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Lorenzo Cupellini
- Dipartimento di Chimica e
Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e
Chimica Industriale, University of Pisa, via G. Moruzzi 13, 56124 Pisa, Italy
| |
Collapse
|
8
|
Kulakova AM, Khrenova MG, Nemukhin AV. Structure and dynamics of photoactivatable adenylyl cyclase. Russ Chem Bull 2019. [DOI: 10.1007/s11172-019-2657-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
9
|
Nemukhin AV, Grigorenko BL, Khrenova MG, Krylov AI. Computational Challenges in Modeling of Representative Bioimaging Proteins: GFP-Like Proteins, Flavoproteins, and Phytochromes. J Phys Chem B 2019; 123:6133-6149. [DOI: 10.1021/acs.jpcb.9b00591] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Alexander V. Nemukhin
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow 119334, Russia
| | - Bella L. Grigorenko
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
- Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow 119334, Russia
| | - Maria G. Khrenova
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
- Federal Research Center of Biotechnology, Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow 119071, Russian
| | - Anna I. Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| |
Collapse
|
10
|
Applications of molecular modeling to flavoproteins: Insights and challenges. Methods Enzymol 2019; 620:277-314. [DOI: 10.1016/bs.mie.2019.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
11
|
Meteleshko YI, Nemukhin AV, Khrenova MG. Novel flavin-based fluorescent proteins with red-shifted emission bands: a computational study. Photochem Photobiol Sci 2018; 18:177-189. [PMID: 30403258 DOI: 10.1039/c8pp00361k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The iLOV protein is a promising member of the class of flavin mononucleotide (FMN) based fluorescent proteins (FbFPs). It is becoming a popular tool for bioanalytical applications and bioimaging as a competitor of the well-known green fluorescent protein and its analogues. The main limitation of FbFPs is that all the members have close values of their absorption and emission band maxima. Therefore the upcoming challenge is to introduce novel variants of FbFPs to extend their color palette. We report the results of computational studies of iLOV variants, introducing point mutations and chromophore analogues. We found that point mutations of the apoprotein and substitution of FMN with either 8-amino-FMN or 8-methylamino-FMN lead to the red shift of emission bands up to 100 nm. Substitution with 1-deaza-FMN and the point mutations of the apoprotein result in a set of novel fluorescent proteins with emission bands in the "transparent" window where light readily penetrates through mammalian tissues. Newly suggested FbFPs can be used for multicolor imaging and also as components of FRET pairs.
Collapse
Affiliation(s)
- Yulia I Meteleshko
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russian Federation.
| | - Alexander V Nemukhin
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russian Federation. and Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygina 4, Moscow, 119334, Russian Federation
| | - Maria G Khrenova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russian Federation. and Federal Research Center of Biotechnology, Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskiy Prospect 33, 119071 Moscow, Russian Federation
| |
Collapse
|
12
|
Xu Y, Bao P, Song K, Shi Q. Theoretical study of proton coupled electron transfer reaction in the light state of the AppA BLUF photoreceptor. J Comput Chem 2018; 40:1005-1014. [PMID: 30341953 DOI: 10.1002/jcc.25561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 07/01/2018] [Accepted: 07/24/2018] [Indexed: 11/10/2022]
Abstract
The BLUF (blue light sensor using flavin adenine dinucleotide) domain is widely studied as a prototype for proton coupled electron transfer (PCET) reactions in biological systems. In this work, the photo-induced concerted PCET reaction from the light state of the AppA BLUF domain is investigated. To model the simultaneous transfer of two protons in the reaction, two-dimensional potential energy surfaces for the double proton transfer are first calculated for the locally excited and charge transfer states, which are then used to obtain the vibrational wave function overlaps and the vibrational energy levels. Contributions to the PCET rate constant from each pair of vibronic states are then analyzed using the theory based on the Fermi's golden rule. We show that, the recently proposed light state structure of the BLUF domain with a tautomerized Gln63 residue is consistent with the concerted transfer of one electron and two protons. It is also found that, thermal fluctuations of the protein structure, especially the proton donor-acceptor distances, play an important role in determining the PCET reaction rate. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Yang Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Peng Bao
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Kai Song
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qiang Shi
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
13
|
Grigorenko BL, Khrenova MG, Nemukhin AV. Amide-imide tautomerization in the glutamine side chain in enzymatic and photochemical reactions in proteins. Phys Chem Chem Phys 2018; 20:23827-23836. [PMID: 30202846 DOI: 10.1039/c8cp04817g] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Amide-imide tautomerization presents a pervasive class of chemical transformations in organic chemistry of natural compounds. In this Perspective, we describe two distinctively different protein systems, in which the amide-imide tautomerization in the glutamine side chain takes place in enzymatic or photochemical reactions. First, hydrolysis of guanosine triphosphate (GTP) catalyzed by the Ras-GAP protein complex suggests the occurrence of the imide tautomer of glutamine in reaction intermediates. Second, photoexcitation of flavin-binding protein domains (BLUFs) initiates a chain of reactions in the chromophore-binding pocket, including amide-imide tautomerization of glutamine. Mechanisms of these reactions at the atomic level have been revealed in quantum mechanics/molecular mechanics (QM/MM) simulations. To reinforce conclusions on the critical role of amide-imide tautomerization of glutamine in these reactions we describe results of new quantum chemistry and QM/MM calculations for relevant molecular model systems. We reexamine results of the recent IR spectroscopy studies of BLUF domains, which provide experimental evidences of Gln tautomerization in proteins. We also propose to validate the glutamine-assisted mechanism of enzymatic GTP hydrolysis by using IR spectroscopy in a proper range of wavenumbers.
Collapse
Affiliation(s)
- Bella L Grigorenko
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russian Federation.
| | | | | |
Collapse
|
14
|
Khrenova MG, Meteleshko YI, Nemukhin AV. Mutants of the Flavoprotein iLOV as Prospective Red-Shifted Fluorescent Markers. J Phys Chem B 2017; 121:10018-10025. [DOI: 10.1021/acs.jpcb.7b07533] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria G. Khrenova
- Department
of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Yulia I. Meteleshko
- Department
of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Alexander V. Nemukhin
- Department
of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
- Emanuel
Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334, Russia
| |
Collapse
|
15
|
Khrenova MG, Domratcheva T, Nemukhin AV. Molecular mechanism of the dark-state recovery in BLUF photoreceptors. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
16
|
Pashandi Z, Molakarimi M, Sajedi RH, Taghdir M, Naderi-Manesh H. Light induced structural changes of the photoprotein mnemiopsin: Characterization and contribution in photoinactivation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 165:133-140. [PMID: 27780117 DOI: 10.1016/j.jphotobiol.2016.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/14/2016] [Indexed: 10/20/2022]
Abstract
Mnemiopsin, an EF-hand Ca2+ binding photoprotein isolated from luminous ctenophore Mnemiopsis leidyi, emits blue light from its chromophore, coelenterazine, which is non-covalently bond in its central hydrophobic core. Previous studies have revealed unique biochemical properties for ctenophore photoproteins such as inactivation by light, but only few have focused on photoinactivation process. To understand the nature of photoinactivation process we have investigated the impact of light alone and in the presence of Ca2+ ion on the structure of this photoprotein. We used UV-Vis, circular dichroism (CD) and fluorescence spectroscopy following Ca2+ binding assay to analyze the light effects on mnemiopsin conformation in comparison with aequorin at both apo and holo form. Our results showed light induced structural changes which resulted into photoinactivation. These changes include significant modification on secondary structure of mnemiopsin in comparison with aequorin. Our data also revealed that light could influence structure of apo protein regardless of presence of coelenterazine. The comparative studies of Ca2+ ion binding affinity following light exposure, also showed that light induced structural changes could presumably affect coelenterazine binding or its conformation in binding site in such a way that causes photoinactivation. In conclusion, we have proposed that structural rearrangement of helix 5 and C-terminal motif could be responsible for light induced structural changes.
Collapse
Affiliation(s)
- Zaiddodine Pashandi
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Maryam Molakarimi
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Reza H Sajedi
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
| | - Majid Taghdir
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Hossein Naderi-Manesh
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
| |
Collapse
|
17
|
Udvarhelyi A, Olivucci M, Domratcheva T. Role of the Molecular Environment in Flavoprotein Color and Redox Tuning: QM Cluster versus QM/MM Modeling. J Chem Theory Comput 2016; 11:3878-94. [PMID: 26574469 DOI: 10.1021/acs.jctc.5b00197] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the origin of the excitation energy shifts induced by the apoprotein in the active site of the bacterial photoreceptor BLUF (Blue Light sensor Using Flavin adenine dinucleotide). In order to compute the vertical excitation energies of three low-lying electronic states, including two π-π* states of flavin (S1 and S2) and a π-π* tyrosine-flavin electron-transfer state (ET), with respect to the energy of the closed-shell ground state (S0), we prepared alternative quantum mechanical (QM) cluster and quantum mechanics/molecular mechanics (QM/MM) models. We found that the excitation energies computed with both types of models correlate with the magnitude of the charge transfer character of the excitation. Accordingly, we conclude that the small charge transfer character of the light absorbing S0-S1 transition and the substantial charge transfer character of the nonabsorbing but redox active S0-ET transition explain the small color changes but substantial redox tuning in BLUF and also in other flavoproteins. Further analysis showed that redox tuning is governed by the electrostatic interaction in the QM/MM model and transfer of charge between the active site and its environment in the QM cluster. Moreover, the wave function polarization of the QM subsystem by the MM subsystem influences the magnitude of the charge transfer, resulting in the QM/MM and QM excitation energies that are not entirely consistent.
Collapse
Affiliation(s)
- Anikó Udvarhelyi
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research , Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Massimo Olivucci
- Dipartimento di Biotecnologie, Chimica e Farmacia, via A. Moro 2, Universitá di Siena , I-53100 Siena, Italy.,Chemistry Department, Overman Hall, Bowling Green State University , Bowling Green, Ohio 67200, United States.,Institut de Physique et de Chimie des Materiaux de Strasbourg, Université de Strasbourg , Batiment 69, 23 Rue du Loess, 67200 Strasbourg, France
| | - Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research , Jahnstrasse 29, 69120 Heidelberg, Germany
| |
Collapse
|
18
|
Domratcheva T, Hartmann E, Schlichting I, Kottke T. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry. Sci Rep 2016; 6:22669. [PMID: 26947391 PMCID: PMC4780082 DOI: 10.1038/srep22669] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/16/2016] [Indexed: 02/02/2023] Open
Abstract
BLUF (blue light sensor using flavin) domains regulate the activity of various enzymatic effector domains in bacteria and euglenids. BLUF features a unique photoactivation through restructuring of the hydrogen-bonding network as opposed to a redox reaction or an isomerization of the chromophore. A conserved glutamine residue close to the flavin chromophore plays a central role in the light response, but the underlying modification is still unclear. We labelled this glutamine with (15)N in two representative BLUF domains and performed time-resolved infrared double difference spectroscopy. The assignment of the signals was conducted by extensive quantum chemical calculations on large models with 187 atoms reproducing the UV-vis and infrared signatures of BLUF photoactivation. In the dark state, the comparatively low frequency of 1,667 cm(-1) is assigned to the glutamine C=O accepting a hydrogen bond from tyrosine. In the light state, the signature of a tautomerised glutamine was extracted with the C=N stretch at ~1,691 cm(-1) exhibiting the characteristic strong downshift by (15)N labelling. Moreover, an indirect isotope effect on the flavin C4=O stretch was found. We conclude that photoactivation of the BLUF receptor does not only involve a rearrangement of hydrogen bonds but includes a change in covalent bonds of the protein.
Collapse
Affiliation(s)
- Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Elisabeth Hartmann
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Ilme Schlichting
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Tilman Kottke
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitäts straße 25, 33615 Bielefeld, Germany
| |
Collapse
|
19
|
Mathes T, Götze JP. A proposal for a dipole-generated BLUF domain mechanism. Front Mol Biosci 2015; 2:62. [PMID: 26579529 PMCID: PMC4630285 DOI: 10.3389/fmolb.2015.00062] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 10/12/2015] [Indexed: 11/25/2022] Open
Abstract
The resting and signaling structures of the blue-light sensing using flavin (BLUF) photoreceptor domains are still controversially debated due to differences in the molecular models obtained by crystal and NMR structures. Photocycles for the given preferred structural framework have been established, but a unifying picture combining experiment and theory remains elusive. We summarize present work on the AppA BLUF domain from both experiment and theory. We focus on IR and UV/vis spectra, and to what extent theory was able to reproduce experimental data and predict the structural changes upon formation of the signaling state. We find that the experimental observables can be theoretically reproduced employing any structural model, as long as the orientation of the signaling essential Gln63 and its tautomer state are a choice of the modeler. We also observe that few approaches are comparative, e.g., by considering all structures in the same context. Based on recent experimental findings and a few basic calculations, we suggest the possibility for a BLUF activation mechanism that only relies on electron transfer and its effect on the local electrostatics, not requiring an associated proton transfer. In this regard, we investigate the impact of dispersion correction on the interaction energies arising from weakly bound amino acids.
Collapse
Affiliation(s)
- Tilo Mathes
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit Amsterdam, Netherlands ; Institut für Biologie/Experimentelle Biophysik, Humboldt Universität zu Berlin Berlin, Germany
| | - Jan P Götze
- School of Chemistry, University of St Andrews St Andrews, UK
| |
Collapse
|
20
|
Khrenova MG, Nemukhin AV, Domratcheva T. Theoretical Characterization of the Flavin-Based Fluorescent Protein iLOV and its Q489K Mutant. J Phys Chem B 2015; 119:5176-83. [DOI: 10.1021/acs.jpcb.5b01299] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria G. Khrenova
- Chemistry
Department, M.V. Lomonosov Moscow State University, Leninskie
Gory 1/3, Moscow, 119991, Russian Federation
| | - Alexander V. Nemukhin
- Chemistry
Department, M.V. Lomonosov Moscow State University, Leninskie
Gory 1/3, Moscow, 119991, Russian Federation
- N.M.
Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygina 4, Moscow, 119334, Russian Federation
| | - Tatiana Domratcheva
- Department
of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| |
Collapse
|
21
|
Collette F, Renger T, Schmidt am Busch M. Revealing the functional states in the active site of BLUF photoreceptors from electrochromic shift calculations. J Phys Chem B 2014; 118:11109-19. [PMID: 25153778 PMCID: PMC4174740 DOI: 10.1021/jp506400y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/22/2014] [Indexed: 11/28/2022]
Abstract
Photoexcitation with blue light of the flavin chromophore in BLUF photoreceptors induces a switch into a metastable signaling state that is characterized by a red-shifted absorption maximum. The red shift is due to a rearrangement in the hydrogen bond pattern around Gln63 located in the immediate proximity of the isoalloxazine ring system of the chromophore. There is a long-lasting controversy between two structural models, named Q63A and Q63J in the literature, on the local conformation of the residues Gln63 and Tyr21 in the dark state of the photoreceptor. As regards the mechanistic details of the light-activation mechanism, rotation of Gln63 is opposed by tautomerism in the Q63A and Q63J models, respectively. We provide a structure-based simulation of electrochromic shifts of the flavin chromophore in the wild type and in various site-directed mutants. The excellent overall agreement between experimental and computed data allows us to evaluate the two structural models. Compelling evidence is obtained that the Q63A model is incorrect, whereas the Q63J is fully consistent with the present computations. Finally, we confirm independently that a keto-enol tautomerization of the glutamine at position 63, which was proposed as molecular mechanism for the transition between the dark and the light-adapted state, explains the measured 10 to 15 nm red shift in flavin absorption between these two states of the protein. We believe that the accurateness of our results provides evidence that the BLUF photoreceptors absorption is fine-tuned through electrostatic interactions between the chromophore and the protein matrix, and finally that the simplicity of our theoretical model is advantageous as regards easy reproducibility and further extensions.
Collapse
Affiliation(s)
- Florimond Collette
- Institut für Theoretische
Physik, Johannes Kepler Universität
Linz, Altenberger Strasse
69, 4040 Linz, Austria
| | - Thomas Renger
- Institut für Theoretische
Physik, Johannes Kepler Universität
Linz, Altenberger Strasse
69, 4040 Linz, Austria
| | - Marcel Schmidt am Busch
- Institut für Theoretische
Physik, Johannes Kepler Universität
Linz, Altenberger Strasse
69, 4040 Linz, Austria
| |
Collapse
|
22
|
Lukacs A, Brust R, Haigney A, Laptenok SP, Addison K, Gil A, Towrie M, Greetham GM, Tonge PJ, Meech SR. BLUF domain function does not require a metastable radical intermediate state. J Am Chem Soc 2014; 136:4605-15. [PMID: 24579721 PMCID: PMC4004230 DOI: 10.1021/ja4121082] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BLUF (blue light using flavin) domain proteins are an important family of blue light-sensing proteins which control a wide variety of functions in cells. The primary light-activated step in the BLUF domain is not yet established. A number of experimental and theoretical studies points to a role for photoinduced electron transfer (PET) between a highly conserved tyrosine and the flavin chromophore to form a radical intermediate state. Here we investigate the role of PET in three different BLUF proteins, using ultrafast broadband transient infrared spectroscopy. We characterize and identify infrared active marker modes for excited and ground state species and use them to record photochemical dynamics in the proteins. We also generate mutants which unambiguously show PET and, through isotope labeling of the protein and the chromophore, are able to assign modes characteristic of both flavin and protein radical states. We find that these radical intermediates are not observed in two of the three BLUF domains studied, casting doubt on the importance of the formation of a population of radical intermediates in the BLUF photocycle. Further, unnatural amino acid mutagenesis is used to replace the conserved tyrosine with fluorotyrosines, thus modifying the driving force for the proposed electron transfer reaction; the rate changes observed are also not consistent with a PET mechanism. Thus, while intermediates of PET reactions can be observed in BLUF proteins they are not correlated with photoactivity, suggesting that radical intermediates are not central to their operation. Alternative nonradical pathways including a keto-enol tautomerization induced by electronic excitation of the flavin ring are considered.
Collapse
Affiliation(s)
- Andras Lukacs
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Domratcheva T, Udvarhelyi A, Shahi ARM. Computational spectroscopy, dynamics, and photochemistry of photosensory flavoproteins. Methods Mol Biol 2014; 1146:191-228. [PMID: 24764094 DOI: 10.1007/978-1-4939-0452-5_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Extensive interest in photosensory proteins stimulated computational studies of flavins and flavoproteins in the past decade. This review is dedicated to the three central topics of these studies: calculations of flavin UV-visible and IR spectra, simulated dynamics of photoreceptor proteins, and flavin photochemistry. Accordingly, this chapter is divided into three parts; each part describes corresponding computational protocols, summarizes computational results, and discusses the emerging mechanistic picture.
Collapse
Affiliation(s)
- Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany,
| | | | | |
Collapse
|
24
|
Fraikin GY, Strakhovskaya MG, Rubin AB. Biological photoreceptors of light-dependent regulatory processes. BIOCHEMISTRY (MOSCOW) 2013; 78:1238-53. [DOI: 10.1134/s0006297913110047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
25
|
Meier K, van Gunsteren WF. On the use of advanced modelling techniques to investigate the conformational discrepancy between two X-ray structures of the AppA BLUF domain. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2012.743659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
26
|
Udvarhelyi A, Domratcheva T. Glutamine Rotamers in BLUF Photoreceptors: A Mechanistic Reappraisal. J Phys Chem B 2013; 117:2888-97. [DOI: 10.1021/jp400437x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anikó Udvarhelyi
- Department of Biomolecular
Mechanisms, Max Planck Institute for Medical Research, Jahnstraße
29, 69120 Heidelberg, Germany
| | - Tatiana Domratcheva
- Department of Biomolecular
Mechanisms, Max Planck Institute for Medical Research, Jahnstraße
29, 69120 Heidelberg, Germany
| |
Collapse
|
27
|
Khrenova MG, Nemukhin AV, Domratcheva T. Photoinduced electron transfer facilitates tautomerization of the conserved signaling glutamine side chain in BLUF protein light sensors. J Phys Chem B 2013; 117:2369-77. [PMID: 23350608 DOI: 10.1021/jp312775x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The BLUF domain (sensor of blue light using flavin adenine dinucleotide) from a bacterial photoreceptor protein AppA undergoes a cascade of chemical transformations, including hydrogen bond rearrangements around the flavin adenine dinucleotide (FAD) chromophore, in response to light illumination. These transformations are initiated by photoinduced electron and proton transfer from a tyrosine residue to the photoexcited flavin which is assisted by a glutamine residue. According to the recent studies, the proton-coupled electron transfer leads to formation of a radical-pair intermediate Tyr•···FADH• and a tautomeric EE form of glutamine in the ground electronic state. This intermediate is a precursor of the light-induced state of the BLUF photoreceptor implicated in biological signaling. In order to describe evolution of the radical pair, we computed reaction pathways on the ground state potential energy surface employing quantum-chemical calculations in the DFT PBE0/cc-pVDZ approximation for a molecular cluster mimicking the chromophore containing pocket of the AppA BLUF protein. We found a minimum-energy pathway comprised of the following consecutive reaction steps: (1) rotation of the imidic group of the EE glutamine side chain around the Cγ-Cδ bond; (2) flip of the OεH group and formation of the ZE form of the glutamine side chain; and (3) biradical recombination via coupled proton and electron transfer, leading to the ZZ form of the glutamine side chain. The potential-energy barriers for stages 1-3 do not exceed 9 kcal/mol. Energy barrier 3 describing the ZE to ZZ glutamine tautomerization is significantly smaller in the BLUF model than in isolated glutamine, since tautomerization in BLUF is facilitated by electron transfer and radical recombination. Thus, our study shows that tautomerization of the conserved glutamine is coupled to the light-induced electron transfer process in BLUF and, thus, is a viable candidate for the photoactivation mechanism which at present is very much debated.
Collapse
Affiliation(s)
- M G Khrenova
- Chemistry Department, M.V. Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow, 119991, Russian Federation.
| | | | | |
Collapse
|
28
|
Grigorenko BL, Nemukhin AV, Morozov DI, Polyakov IV, Bravaya KB, Krylov AI. Toward Molecular-Level Characterization of Photoinduced Decarboxylation of the Green Fluorescent Protein: Accessibility of the Charge-Transfer States. J Chem Theory Comput 2012; 8:1912-20. [DOI: 10.1021/ct300043e] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bella L. Grigorenko
- Department
of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991,
Russia
| | - Alexander V. Nemukhin
- Department
of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991,
Russia
- Institute of Biochemical
Physics, Russian Academy of Sciences, Moscow
119334, Russia
| | - Dmitry I. Morozov
- Department
of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991,
Russia
| | - Igor V. Polyakov
- Department
of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991,
Russia
| | - Ksenia B. Bravaya
- Department
of Chemistry, University of Southern California, Los Angeles, California
90089-0482, United States
| | - Anna I. Krylov
- Department
of Chemistry, University of Southern California, Los Angeles, California
90089-0482, United States
| |
Collapse
|
29
|
Bravaya KB, Subach OM, Korovina N, Verkhusha VV, Krylov AI. Insight into the common mechanism of the chromophore formation in the red fluorescent proteins: the elusive blue intermediate revealed. J Am Chem Soc 2012; 134:2807-14. [PMID: 22239269 PMCID: PMC3310345 DOI: 10.1021/ja2114568] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the chromophore maturation process in fluorescent proteins is important for the design of proteins with improved properties. Here, we present the results of electronic structure calculations identifying the nature of a blue intermediate, a key species in the process of the red chromophore formation in DsRed, TagRFP, fluorescent timers, and PAmCherry. The chromophore of the blue intermediate has a structure in which the π-system of the imidazole ring is extended by the acylimine bond, which can be represented by the model N-[(5-hydroxy-1H-imidazole-2yl)methylidene]acetamide (HIMA) compound. Ab initio and QM/MM calculations of the isolated model and protein-bound (mTagBFP) chromophores identify the anionic form of HIMA as the only structure that has absorption that is consistent with the experiment and is stable in the protein binding pocket. The anion and zwitterion are the only protonation forms of HIMA whose absorption (421 and 414 nm, or 2.95 and 3.00 eV) matches the experimental spectrum of the blue form in DsRed (the absorption maximum is 408 nm or 3.04 eV) and mTagBFP (400 nm or 3.10 eV). The QM/MM optimization of the protein-bound anionic form results in a structure that is close to the X-ray one, whereas the zwitterionic chromophore is unstable in the protein binding pocket and undergoes prompt proton transfer. The computed excitation energy of the protein-bound anionic form of the mTagBFP-like chromophore (3.04 eV) agrees with the experimental absorption spectrum of the protein. The DsRed-like chromophore formation in red fluorescent proteins is revisited on the basis of ab initio results and verified by directed mutagenesis revealing a key role of the amino acid residue 70, which is the second after the chromophore tripeptide, in the formation process.
Collapse
Affiliation(s)
- Ksenia B. Bravaya
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0482
| | - Oksana M. Subach
- Department of Anatomy and Structural Biology, and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Nadezhda Korovina
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0482
| | - Vladislav V. Verkhusha
- Department of Anatomy and Structural Biology, and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Anna I. Krylov
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0482
| |
Collapse
|
30
|
Losi A, Gärtner W. The evolution of flavin-binding photoreceptors: an ancient chromophore serving trendy blue-light sensors. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:49-72. [PMID: 22136567 DOI: 10.1146/annurev-arplant-042811-105538] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Photoreceptor flavoproteins of the LOV, BLUF, and cryptochrome families are ubiquitous among the three domains of life and are configured as UVA/blue-light systems not only in plants-their original arena-but also in prokaryotes and microscopic algae. Here, we review these proteins' structure and function, their biological roles, and their evolution and impact in the living world, and underline their growing application in biotechnologies. We present novel developments such as the interplay of light and redox stimuli, emerging enzymatic and biological functions, lessons on evolution from picoalgae, metagenomics analysis, and optogenetics applications.
Collapse
Affiliation(s)
- Aba Losi
- Department of Physics, University of Parma, Parma, Italy.
| | | |
Collapse
|
31
|
Lukacs A, Haigney A, Brust R, Zhao RK, Stelling AL, Clark IP, Towrie M, Greetham GM, Meech SR, Tonge PJ. Photoexcitation of the blue light using FAD photoreceptor AppA results in ultrafast changes to the protein matrix. J Am Chem Soc 2011; 133:16893-900. [PMID: 21899315 DOI: 10.1021/ja2060098] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoexcitation of the flavin chromophore in the BLUF photosensor AppA results in a conformational change that leads to photosensor activation. This conformational change is mediated by a hydrogen-bonding network that surrounds the flavin, and photoexcitation is known to result in changes in the network that include a strengthening of hydrogen bonding to the flavin C4═O carbonyl group. Q63 is a key residue in the hydrogen-bonding network, and replacement of this residue with a glutamate results in a photoinactive mutant. While the ultrafast time-resolved infrared (TRIR) spectrum of Q63E AppA(BLUF) is characterized by flavin carbonyl modes at 1680 and 1650 cm(-1), which are similar in frequency to the analogous modes from the light activated state of the wild-type protein, a band is also observed in the TRIR spectrum at 1724 cm(-1) that is unambiguously assigned to the Q63E carboxylic acid based on U-(13)C labeling of the protein. Light absorption instantaneously (<100 fs) bleaches the 1724 cm(-1) band leading to a transient absorption at 1707 cm(-1). Because Q63E is not part of the isoalloxazine electronic transition, the shift in frequency must arise from a sub picosecond perturbation to the flavin binding pocket. The light-induced change in the frequency of the Q63E side chain is assigned to an increase in hydrogen-bond strength of 3 kcal mol(-1) caused by electronic reorganization of the isoalloxazine ring in the excited state, providing direct evidence that the protein matrix of AppA responds instantaneously to changes in the electronic structure of the chromophore and supporting a model for photoactivation of the wild-type protein that involves initial tautomerization of the Q63 side chain.
Collapse
Affiliation(s)
- Andras Lukacs
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Bravaya KB, Khrenova MG, Grigorenko BL, Nemukhin AV, Krylov AI. Effect of Protein Environment on Electronically Excited and Ionized States of the Green Fluorescent Protein Chromophore. J Phys Chem B 2011; 115:8296-303. [DOI: 10.1021/jp2020269] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ksenia B. Bravaya
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Maria G. Khrenova
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991, Russia
| | - Bella L. Grigorenko
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991, Russia
| | - Alexander V. Nemukhin
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991, Russia
- N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow 119334, Russia
| | - Anna I. Krylov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| |
Collapse
|
33
|
Mathes T, van Stokkum IHM, Bonetti C, Hegemann P, Kennis JTM. The Hydrogen-Bond Switch Reaction of the Blrb Bluf Domain of Rhodobacter sphaeroides. J Phys Chem B 2011; 115:7963-71. [DOI: 10.1021/jp201296m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Tilo Mathes
- Institut für Biologie/Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Ivo H. M. van Stokkum
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Cosimo Bonetti
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Peter Hegemann
- Institut für Biologie/Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - John T. M. Kennis
- Biophysics Group, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| |
Collapse
|
34
|
Losi A, Gärtner W. Old Chromophores, New Photoactivation Paradigms, Trendy Applications: Flavins in Blue Light-Sensing Photoreceptors†. Photochem Photobiol 2011; 87:491-510. [DOI: 10.1111/j.1751-1097.2011.00913.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
35
|
Udvarhelyi A, Domratcheva T. Photoreaction in BLUF Receptors: Proton-coupled Electron Transfer in the Flavin-Gln-Tyr System†. Photochem Photobiol 2011; 87:554-63. [DOI: 10.1111/j.1751-1097.2010.00884.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
36
|
Khrenova MG, Domratcheva T, Schlichting I, Grigorenko BL, Nemukhin AV. Computational characterization of reaction intermediates in the photocycle of the sensory domain of the AppA blue light photoreceptor. Photochem Photobiol 2010; 87:564-73. [PMID: 21155828 DOI: 10.1111/j.1751-1097.2010.00861.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The AppA protein with the BLUF (blue light using flavin adenine dinucleotide) domain is a blue light photoreceptor that cycle between dark-adapted and light-induced functional states. We characterized possible reaction intermediates in the photocycle of AppA BLUF. Molecular dynamics (MD), quantum chemical and quantum mechanical-molecular mechanical (QM/MM) calculations were carried out to describe several stable structures of a molecular system modeling the protein. The coordinates of heavy atoms from the crystal structure (PDB code 2IYG) of the protein in the dark state served as starting point for 10 ns MD simulations. Representative MD frames were used in QM(B3LYP/cc-pVDZ)/MM(AMBER) calculations to locate minimum energy configurations of the model system. Vertical electronic excitation energies were estimated for the molecular clusters comprising the quantum subsystems of the QM/MM optimized structures using the SOS-CIS(D) quantum chemistry method. Computational results support the occurrence of photoreaction intermediates that are characterized by spectral absorption bands between those of the dark and light states. They agree with crystal structures of reaction intermediates (PDB code 2IYI) observed in the AppA BLUF domain. Transformations of the Gln63 side chain stimulated by photo-excitation and performed with the assistance of the chromophore and the Met106 side chain are responsible for these intermediates.
Collapse
Affiliation(s)
- Maria G Khrenova
- Department of Chemistry, M V Lomonosov Moscow State University, Moscow, Russia.
| | | | | | | | | |
Collapse
|