1
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Roy P, Sardjan AS, Browne WR, Feringa BL, Meech SR. Excited State Dynamics in Unidirectional Photochemical Molecular Motors. J Am Chem Soc 2024; 146:12255-12270. [PMID: 38656968 PMCID: PMC11082934 DOI: 10.1021/jacs.4c01019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 04/26/2024]
Abstract
Unidirectional photochemically driven molecular motors (PMMs) convert the energy of absorbed light into continuous rotational motion. As such they are key components in the design of molecular machines. The prototypical and most widely employed class of PMMs is the overcrowded alkenes, where rotational motion is driven by successive photoisomerization and thermal helix inversion steps. The efficiency of such PMMs depends upon the speed of rotation, determined by the rate of ground state thermal helix inversion, and the quantum yield of photoisomerization, which is dependent on the excited state energy landscape. The former has been optimized by synthetic modification across three generations of overcrowded alkene PMMs. These improvements have often been at the expense of photoisomerization yield, where there remains room for improvement. In this perspective we review the application of ultrafast spectroscopy to characterize the excited state dynamics in PMMs. These measurements lead to a general mechanism for all generations of PMMs, involving subpicosecond decay of a Franck-Condon excited state to populate a dark excited state which decays within picoseconds via conical intersections with the electronic ground state. The model is discussed in the context of excited state dynamics calculations. Studies of PMM photochemical dynamics as a function of solvent suggest exploitation of intramolecular charge transfer and solvent polarity as a route to controlling photoisomerization yield. A test of these ideas for a first generation motor reveals a high degree of solvent control over isomerization yield. These results suggest a pathway to fine control over the performance of future PMMs.
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Affiliation(s)
- Palas Roy
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
- School
of Basic Sciences, Indian Institute of Technology
Bhubaneswar, Bhubaneswar, Odisha 752050, India
| | - Andy S. Sardjan
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747AG Groningen, The Netherlands
| | - Wesley R. Browne
- Molecular
Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747AG Groningen, The Netherlands
| | - Ben L. Feringa
- Centre
for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747AG Groningen, The Netherlands
| | - Stephen R. Meech
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
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2
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He Y, Collado JT, Iuliano JN, Woroniecka HA, Hall CR, Gil AA, Laptenok SP, Greetham GM, Illarionov B, Bacher A, Fischer M, French JB, Lukacs A, Meech SR, Tonge PJ. Elucidating the Signal Transduction Mechanism of the Blue-Light-Regulated Photoreceptor YtvA: From Photoactivation to Downstream Regulation. ACS Chem Biol 2024; 19:696-706. [PMID: 38385342 PMCID: PMC10949197 DOI: 10.1021/acschembio.3c00722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/25/2024] [Accepted: 02/12/2024] [Indexed: 02/23/2024]
Abstract
The blue-light photoreceptor YtvA from Bacillus subtilis has an N-terminal flavin mononucleotide (FMN)-binding light-oxygen-voltage (LOV) domain that is fused to a C-terminal sulfate transporter and anti-σ factor antagonist (STAS) output domain. To interrogate the signal transduction pathway that leads to photoactivation, the STAS domain was replaced with a histidine kinase, so that photoexcitation of the flavin could be directly correlated with biological activity. N94, a conserved Asn that is hydrogen bonded to the FMN C2═O group, was replaced with Ala, Asp, and Ser residues to explore the role of this residue in triggering the structural dynamics that activate the output domain. Femtosecond to millisecond time-resolved multiple probe spectroscopy coupled with a fluorescence polarization assay revealed that the loss of the hydrogen bond between N94 and the C2═O group decoupled changes in the protein structure from photoexcitation. In addition, alterations in N94 also decreased the stability of the Cys-FMN adduct formed in the light-activated state by up to a factor of ∼25. Collectively, these studies shed light on the role of the hydrogen bonding network in the LOV β-scaffold in signal transduction.
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Affiliation(s)
- YongLe He
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | | | - James N. Iuliano
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Helena A. Woroniecka
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | - Christopher R. Hall
- Central
Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K.
| | - Agnieszka A. Gil
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
| | | | - Gregory M. Greetham
- Central
Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K.
| | - Boris Illarionov
- Institut
für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Adelbert Bacher
- Institut
für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
- TUM School
of Natural Sciences, Technical University
of Munich, 85747 Garching, Germany
| | - Markus Fischer
- Institut
für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Jarrod B. French
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
- The
Hormel Institute, University of Minnesota, Austin, Minnesota 55912, United States
| | - Andras Lukacs
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
- Department
of Biophysics, Medical School, University
of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Stephen R. Meech
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
| | - Peter J. Tonge
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
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3
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Bressan G, Green D, Jones GA, Heisler IA, Meech SR. Two-Dimensional Electronic Spectroscopy Resolves Relative Excited-State Displacements. J Phys Chem Lett 2024; 15:2876-2884. [PMID: 38447068 PMCID: PMC10945572 DOI: 10.1021/acs.jpclett.3c03420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/09/2024] [Accepted: 03/01/2024] [Indexed: 03/08/2024]
Abstract
Knowledge of relative displacements between potential energy surfaces (PES) is critical in spectroscopy and photochemistry. Information on displacements is encoded in vibrational coherences. Here we apply ultrafast two-dimensional electronic spectroscopy in a pump-probe half-broadband (HB2DES) geometry to probe the ground- and excited-state potential landscapes of cresyl violet. 2D coherence maps reveal that while the coherence amplitude of the dominant 585 cm-1 Raman-active mode is mainly localized in the ground-state bleach and stimulated emission regions, a 338 cm-1 mode is enhanced in excited-state absorption. Modeling these data with a three-level displaced harmonic oscillator model using the hierarchical equation of motion-phase matching approach (HEOM-PMA) shows that the S1 ← S0 PES displacement is greater along the 585 cm-1 coordinate than the 338 cm-1 coordinate, while Sn ← S1 displacements are similar along both coordinates. HB2DES is thus a powerful tool for exploiting nuclear wavepackets to extract quantitative multidimensional, vibrational coordinate information across multiple PESs.
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Affiliation(s)
- Giovanni Bressan
- School
of Chemistry, Norwich Research Park, University
of East Anglia, Norwich NR4 7TJ, United
Kingdom
| | - Dale Green
- School
of Chemistry, Norwich Research Park, University
of East Anglia, Norwich NR4 7TJ, United
Kingdom
| | - Garth A. Jones
- School
of Chemistry, Norwich Research Park, University
of East Anglia, Norwich NR4 7TJ, United
Kingdom
| | - Ismael A. Heisler
- Instituto
de Fisica, Universidade Federal do Rio Grande
do Sul, 91509-900 Porto Alegre, RS, Brazil
| | - Stephen R. Meech
- School
of Chemistry, Norwich Research Park, University
of East Anglia, Norwich NR4 7TJ, United
Kingdom
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4
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Tolentino Collado J, Bodis E, Pasitka J, Szucs M, Fekete Z, Kis-Bicskei N, Telek E, Pozsonyi K, Kapetanaki SM, Greetham G, Tonge PJ, Meech SR, Lukacs A. Single Amino Acid Mutation Decouples Photochemistry of the BLUF Domain from the Enzymatic Function of OaPAC and Drives the Enzyme to a Switched-on State. J Mol Biol 2024; 436:168312. [PMID: 37827329 DOI: 10.1016/j.jmb.2023.168312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/29/2023] [Accepted: 10/05/2023] [Indexed: 10/14/2023]
Abstract
Photoactivated adenylate cyclases (PACs) are light-activated enzymes that combine a BLUF (blue-light using flavin) domain and an adenylate cyclase domain that are able to increase the levels of the important second messenger cAMP (cyclic adenosine monophosphate) upon blue-light excitation. The light-induced changes in the BLUF domain are transduced to the adenylate cyclase domain via a mechanism that has not yet been established. One critical residue in the photoactivation mechanism of BLUF domains, present in the vicinity of the flavin is the glutamine amino acid close to the N5 of the flavin. The role of this residue has been investigated extensively both experimentally and theoretically. However, its role in the activity of the photoactivated adenylate cyclase, OaPAC has never been addressed. In this work, we applied ultrafast transient visible and infrared spectroscopies to study the photochemistry of the Q48E OaPAC mutant. This mutation altered the primary electron transfer process and switched the enzyme into a permanent 'on' state, able to increase the cAMP levels under dark conditions compared to the cAMP levels of the dark-adapted state of the wild-type OaPAC. Differential scanning calorimetry measurements point to a less compact structure for the Q48E OaPAC mutant. The ensemble of these findings provide insight into the important elements in PACs and how their fine tuning may help in the design of optogenetic devices.
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Affiliation(s)
| | - Emoke Bodis
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Jonatan Pasitka
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Mihaly Szucs
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Zsuzsanna Fekete
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Nikolett Kis-Bicskei
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Elek Telek
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Kinga Pozsonyi
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Sofia M Kapetanaki
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary
| | - Greg Greetham
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University, New York 11794, United States.
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti str. 12, 7624 Pecs, Hungary.
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5
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Roy P, Sardjan AS, Danowski W, Browne WR, Feringa BL, Meech SR. Control of Photoconversion Yield in Unidirectional Photomolecular Motors by Push-Pull Substituents. J Am Chem Soc 2023; 145:19849-19855. [PMID: 37646616 PMCID: PMC10510317 DOI: 10.1021/jacs.3c06070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Indexed: 09/01/2023]
Abstract
Molecular motors based on the overcrowded alkene motif convert light energy into unidirectional mechanical motion through an excited state isomerization reaction. The realization of experimental control over conversion efficiency in these molecular motors is an important goal. Here, we combine the synthesis of a novel "push-pull" overcrowded alkene motor with photophysical characterization by steady state and ultrafast time-resolved electronic spectroscopy. We show that tuning of the charge transfer character in the excited state has a dramatic effect on the photoisomerization yield, enhancing it to near unity in nonpolar solvents while largely suppressing it in polar solvents. This behavior is explained through reference to solvent- and substituent-dependent potential energy surfaces and their effect on conical intersections to the ground state. These observations offer new routes to the fine control of motor efficiency and introduce additional degrees of freedom in the synthesis and exploitation of light-driven molecular motors.
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Affiliation(s)
- Palas Roy
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
- School
of Basic Sciences, Indian Institute of Technology
Bhubaneswar, Bhubaneswar, Odisha 752050, India
| | - Andy S. Sardjan
- Molecular
Inorganic Chemistry, Stratingh Institute
for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Wojciech Danowski
- Centre
for Systems Chemistry, Stratingh Institute
for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
- University
of Strasbourg, CNRS, ISIS UMR 7006, 8 allée Gaspard Monge, F-67000 Strasbourg, France
| | - Wesley R. Browne
- Molecular
Inorganic Chemistry, Stratingh Institute
for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Ben L. Feringa
- Centre
for Systems Chemistry, Stratingh Institute
for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Stephen R. Meech
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
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6
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Ashworth EK, Kao MH, Anstöter CS, Riesco-Llach G, Blancafort L, Solntsev KM, Meech SR, Verlet JRR, Bull JN. Alkylated green fluorescent protein chromophores: dynamics in the gas phase and in aqueous solution. Phys Chem Chem Phys 2023; 25:23626-23636. [PMID: 37649445 DOI: 10.1039/d3cp03250g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Fluorescent labelling of macromolecular samples, including using the green fluorescent protein (GFP), has revolutionised the field of bioimaging. The ongoing development of fluorescent proteins require a detailed understanding of the photophysics of the biochromophore, and how chemical derivatisation influences the excited state dynamics. Here, we investigate the photophysical properties associated with the S1 state of three alkylated derivatives of the chromophore in GFP, in the gas phase using time-resolved photoelectron imaging, and in water using femtosecond fluorescence upconversion. The gas-phase lifetimes (1.6-10 ps), which are associated with the intrinsic (environment independent) dynamics, are substantially longer than the lifetimes in water (0.06-3 ps), attributed to stabilisation of both twisted intermediate structures and conical intersection seams in the condensed phase. In the gas phase, alkylation on the 3 and 5 positions of the phenyl ring slows the dynamics due to inertial effects, while a 'pre-twist' of the methine bridge through alkylation on the 2 and 6 positions significantly shortens the excited state lifetimes. Formation of a minor, long-lived (≫ 40 ps) excited state population in the gas phase is attributed to intersystem crossing to a triplet state, accessed because of a T1/S1 degeneracy in the so-called P-trap potential energy minimum associated with torsion of the single-bond in the bridging unit connecting to the phenoxide ring. A small amount of intersystem crossing is supported through TD-DFT molecular dynamics trajectories and MS-CASPT2 calculations. No such intersystem crossing occurs in water at T = 300 K or in ethanol at T ≈ 77 K, due to a significantly altered potential energy surface and P-trap geometry.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Min-Hsien Kao
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Cate S Anstöter
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Gerard Riesco-Llach
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/M.A. Capmany 69, 17003 Girona, Spain
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, C/M.A. Capmany 69, 17003 Girona, Spain
| | - Kyril M Solntsev
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Stephen R Meech
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich, NR4 7TJ, UK.
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich, NR4 7TJ, UK.
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7
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Verma P, Tasior M, Roy P, Meech SR, Gryko DT, Vauthey E. Excited-state symmetry breaking in quadrupolar pull-push-pull molecules: dicyanovinyl vs. cyanophenyl acceptors. Phys Chem Chem Phys 2023; 25:22689-22699. [PMID: 37602791 PMCID: PMC10467566 DOI: 10.1039/d3cp02810k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/02/2023] [Indexed: 08/22/2023]
Abstract
A significant number of quadrupolar dyes behave as their dipolar analogues when photoexcited in polar environments. This is due to the occurrence of excited-state symmetry breaking (ES-SB), upon which the electronic excitation, initially distributed over the whole molecule, localises preferentially on one side. Here, we investigate the ES-SB properties of two A-D-A dyes, consisting of a pyrrolo-pyrrole donor (D) and either cyanophenyl or dicyanovinyl acceptors (A). For this, we use time-resolved vibrational spectroscopy, comparing IR absorption and femtosecond stimulated Raman spectroscopies. Although dicyanovinyl is a stronger electron-withdrawing group, ES-SB is not observed with the dicyanovinyl-based dye even in highly polar media, whereas it already takes place in weakly polar solvents with dyes containing cyanophenyl accepting groups. This difference is attributed to the large electronic coupling between the D-A branches in the former dye, whose loss upon symmetry breaking cannot be counterbalanced by a gain in solvation energy. Comparison with analogues of the cyanophenyl-based dye containing different spacers reveals that interbranch coupling does not so much depend on the distance between the D-A subunits than on the nature of the spacer. We show that transient Raman spectra probe different modes of these centrosymmetric molecules but are consistent with the transient IR data. However, lifetime broadening of the Raman bands, probably due to the resonance enhancement, may limit the application of this technique for monitoring ES-SB.
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Affiliation(s)
- Pragya Verma
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211, Geneva 4, Switzerland.
| | - Mariusz Tasior
- Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Palas Roy
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Daniel T Gryko
- Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Eric Vauthey
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211, Geneva 4, Switzerland.
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8
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Raics K, Pirisi K, Zhuang B, Fekete Z, Kis-Bicskei N, Pecsi I, Ujfalusi KP, Telek E, Li Y, Collado JT, Tonge PJ, Meech SR, Vos MH, Bodis E, Lukacs A. Photocycle alteration and increased enzymatic activity in genetically modified photoactivated adenylate cyclase OaPAC. J Biol Chem 2023; 299:105056. [PMID: 37468104 PMCID: PMC10448171 DOI: 10.1016/j.jbc.2023.105056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/30/2023] [Accepted: 07/11/2023] [Indexed: 07/21/2023] Open
Abstract
Photoactivated adenylate cyclases (PACs) are light activated enzymes that combine blue light sensing capacity with the ability to convert ATP to cAMP and pyrophosphate (PPi) in a light-dependent manner. In most of the known PACs blue light regulation is provided by a blue light sensing domain using flavin which undergoes a structural reorganization after blue-light absorption. This minor structural change then is translated toward the C-terminal of the protein, inducing a larger conformational change that results in the ATP conversion to cAMP. As cAMP is a key second messenger in numerous signal transduction pathways regulating various cellular functions, PACs are of great interest in optogenetic studies. The optimal optogenetic device must be "silent" in the dark and highly responsive upon light illumination. PAC from Oscillatoria acuminata is a very good candidate as its basal activity is very small in the dark and the conversion rates increase 20-fold upon light illumination. We studied the effect of replacing D67 to N, in the blue light using flavin domain. This mutation was found to accelerate the primary electron transfer process in the photosensing domain of the protein, as has been predicted. Furthermore, it resulted in a longer lived signaling state, which was formed with a lower quantum yield. Our studies show that the overall effects of the D67N mutation lead to a slightly higher conversion of ATP to cAMP, which points in the direction that by fine tuning the kinetic properties more responsive PACs and optogenetic devices can be generated.
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Affiliation(s)
- Katalin Raics
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary
| | - Katalin Pirisi
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary
| | - Bo Zhuang
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Palaiseau, France
| | - Zsuzsanna Fekete
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary
| | | | - Ildiko Pecsi
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary
| | | | - Elek Telek
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary
| | - Yin Li
- Department of Physics, School of Physics and Materials Science, Nanchang University, Nanchang City, China
| | | | - Peter J Tonge
- Department of Chemistry, Stony Brook University, New York, USA
| | | | - Marten H Vos
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Palaiseau, France
| | - Emoke Bodis
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary.
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary.
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9
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Roy P, Browne WR, Feringa BL, Meech SR. Ultrafast motion in a third generation photomolecular motor. Nat Commun 2023; 14:1253. [PMID: 36878920 PMCID: PMC9988961 DOI: 10.1038/s41467-023-36777-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 02/13/2023] [Indexed: 03/08/2023] Open
Abstract
Controlling molecular translation at the nanoscale is a key objective for development of synthetic molecular machines. Recently developed third generation photochemically driven molecular motors (3GMs), comprising pairs of overcrowded alkenes capable of cooperative unidirectional rotation offer the possibility of converting light energy into translational motion. Further development of 3GMs demands detailed understanding of their excited state dynamics. Here we use time-resolved absorption and emission to track population and coherence dynamics in a 3GM. Femtosecond stimulated Raman reveals real-time structural dynamics as the excited state evolves from a Franck-Condon bright-state through weakly-emissive dark-state to the metastable product, yielding new insight into the reaction coordinate. Solvent polarity modifies the photoconversion efficiency suggesting charge transfer character in the dark-state. The enhanced quantum yield correlates with suppression of a low-frequency flapping motion in the excited state. This detailed characterization facilitates development of 3GMs, suggesting exploitation of medium and substituent effects to modulate motor efficiency.
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Affiliation(s)
- Palas Roy
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom.,School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Argul, Odisha, 752050, India
| | - Wesley R Browne
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Ben L Feringa
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands.
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom.
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10
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Roy P, Al-Kahtani F, Cammidge AN, Meech SR. Solvent Tuning Excited State Structural Dynamics in a Novel Bianthryl. J Phys Chem Lett 2023; 14:253-259. [PMID: 36594925 PMCID: PMC9841557 DOI: 10.1021/acs.jpclett.2c03469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
Symmetry breaking charge separation (SBCS) is central to photochemical energy conversion. The widely studied 9,9-bianthryl (9,9'BA) is the prototype, but the role of bianthryl structure is hardly investigated. Here we investigate excited state structural dynamics in a bianthryl of reduced symmetry, 1,9-bianthryl (1,9'BA), through ultrafast electronic and vibrational spectroscopy. Resonance selective Raman in polar solvents reveals a Franck-Condon state mode that disappears concomitant with the rise of ring breathing modes of radical species. Solvent-dependent dynamics show that CS is driven by solvent orientational motion, as in 9,9'BA. In nonpolar solvents the excited state undergoes multistep structural relaxation, including subpicosecond Franck-Condon state decay and biexponential diffusion-controlled structural evolution to a distorted slightly polar state. These data suggest two possible routes to SBCS; the established solvent driven pathway in rapidly relaxing polar solvents and, in slowly relaxing media, initial intramolecular reorganization to a polar structure which drives solvent orientational relaxation.
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11
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Addison K, Roy P, Bressan G, Skudaite K, Robb J, Bulman Page PC, Ashworth EK, Bull JN, Meech SR. Photophysics of the red-form Kaede chromophore. Chem Sci 2023; 14:3763-3775. [PMID: 37035701 PMCID: PMC10074405 DOI: 10.1039/d3sc00368j] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/08/2023] [Indexed: 03/18/2023] Open
Abstract
The chromophore responsible for colour switching in the optical highlighting protein Kaede has unexpectedly complicated excited state dynamics, which are measured and analysed here. This will inform the development of new imaging proteins.
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Affiliation(s)
- Kiri Addison
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Palas Roy
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Giovanni Bressan
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Karolina Skudaite
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Josh Robb
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | | | - Eleanor K. Ashworth
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - James N. Bull
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
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12
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Tolentino Collado J, Iuliano JN, Pirisi K, Jewlikar S, Adamczyk K, Greetham GM, Towrie M, Tame JRH, Meech SR, Tonge PJ, Lukacs A. Unraveling the Photoactivation Mechanism of a Light-Activated Adenylyl Cyclase Using Ultrafast Spectroscopy Coupled with Unnatural Amino Acid Mutagenesis. ACS Chem Biol 2022; 17:2643-2654. [PMID: 36038143 PMCID: PMC9486806 DOI: 10.1021/acschembio.2c00575] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The hydrogen bonding network that surrounds the flavin in blue light using flavin adenine dinucleotide (BLUF) photoreceptors plays a crucial role in sensing and communicating the changes in the electronic structure of the flavin to the protein matrix upon light absorption. Using time-resolved infrared spectroscopy (TRIR) and unnatural amino acid incorporation, we investigated the photoactivation mechanism and the role of the conserved tyrosine (Y6) in the forward reaction of the photoactivated adenylyl cyclase from Oscillatoria acuminata (OaPAC). Our work elucidates the direct connection between BLUF photoactivation and the structural and functional implications on the partner protein for the first time. The TRIR results demonstrate the formation of the neutral flavin radical as an intermediate species on the photoactivation pathway which decays to form the signaling state. Using fluorotyrosine analogues to modulate the physical properties of Y6, the TRIR data reveal that a change in the pKa and/or reduction potential of Y6 has a profound effect on the forward reaction, consistent with a mechanism involving proton transfer or proton-coupled electron transfer from Y6 to the electronically excited FAD. Decreasing the pKa from 9.9 to <7.2 and/or increasing the reduction potential by 200 mV of Y6 prevents proton transfer to the flavin and halts the photocycle at FAD•-. The lack of protonation of the anionic flavin radical can be directly linked to photoactivation of the adenylyl cyclase (AC) domain. While the 3F-Y6 and 2,3-F2Y6 variants undergo the complete photocycle and catalyze the conversion of ATP into cAMP, enzyme activity is abolished in the 3,5-F2Y6 and 2,3,5-F3Y6 variants where the photocycle is halted at FAD•-. Our results thus show that proton transfer plays an essential role in initiating the structural reorganization of the AC domain that results in AC activity.
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Affiliation(s)
| | - James N. Iuliano
- Department
of Chemistry, Stony Brook University, New York, New York 11794, United States
| | - Katalin Pirisi
- Department
of Biophysics, Medical School, University
of Pecs, Szigeti Street 12, Pecs 7624, Hungary
| | - Samruddhi Jewlikar
- Department
of Chemistry, Stony Brook University, New York, New York 11794, United States
| | - Katrin Adamczyk
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
| | - Gregory M. Greetham
- Central
Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K.
| | - Michael Towrie
- Central
Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, U.K.
| | - Jeremy R. H. Tame
- Drug
Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Tsurumi, Yokohama 230-0045, Japan
| | - Stephen R. Meech
- School
of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.,
| | - Peter J. Tonge
- Department
of Chemistry, Stony Brook University, New York, New York 11794, United States,
| | - Andras Lukacs
- Department
of Biophysics, Medical School, University
of Pecs, Szigeti Street 12, Pecs 7624, Hungary,
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13
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Ashworth EK, Stockett MH, Kjær C, Bulman Page PC, Meech SR, Nielsen SB, Bull JN. Complexation of Green and Red Kaede Fluorescent Protein Chromophores by a Zwitterion to Probe Electrostatic and Induction Field Effects. J Phys Chem A 2022; 126:1158-1167. [PMID: 35138862 DOI: 10.1021/acs.jpca.1c10628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photophysics of green fluorescent protein (GFP) and red Kaede fluorescent protein (rKFP) are defined by the intrinsic properties of the light-absorbing chromophore and its interaction with the protein binding pocket. This work deploys photodissociation action spectroscopy to probe the absorption profiles for a series of synthetic GFP and rKFP chromophores as the bare anions and as complexes with the betaine zwitterion, which is assumed as a model for dipole microsolvation. Electronic structure calculations and energy decomposition analysis using Symmetry-Adapted Perturbation Theory are used to characterize gas-phase structures and complex cohesion forces. The calculations reveal a preponderance for coordination of betaine to the phenoxide deprotonation site predominantly through electrostatic forces. Calculations using the STEOM-DLPNO-CCSD method are able to reproduce absolute and relative vertical excitation energies for the bare anions and anion-betaine complexes. On the other hand, treatment of the betaine molecule with a point-charge model, in which the charges are computed from some common electron density population analysis schemes, show that just electrostatic and point-charge induction interactions are unable to account for the betaine-induced spectral shift. The present methodology could be applied to investigate cluster forces and optical properties in other gas-phase ion-zwitterion complexes.
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Affiliation(s)
- Eleanor K Ashworth
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000, Denmark
| | - Philip C Bulman Page
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | | | - James N Bull
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
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14
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Uriarte LM, Vitale R, Niziński S, Hadjidemetriou K, Zala N, Lukacs A, Greetham GM, Sazanovich IV, Weik M, Ruckebusch C, Meech SR, Sliwa M. Structural Information about the trans-to- cis Isomerization Mechanism of the Photoswitchable Fluorescent Protein rsEGFP2 Revealed by Multiscale Infrared Transient Absorption. J Phys Chem Lett 2022; 13:1194-1202. [PMID: 35085441 DOI: 10.1021/acs.jpclett.1c02920] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
RsEGFP2 is a reversibly photoswitchable fluorescent protein used in super-resolved optical microscopies, which can be toggled between a fluorescent On state and a nonfluorescent Off state. Previous time-resolved ultraviolet-visible spectroscopic studies have shown that the Off-to-On photoactivation extends over the femto- to millisecond time scale and involves two picosecond lifetime excited states and four ground state intermediates, reflecting a trans-to-cis excited state isomerization, a millisecond deprotonation, and protein structural reorganizations. Femto- to millisecond time-resolved multiple-probe infrared spectroscopy (TRMPS-IR) can reveal structural aspects of intermediate species. Here we apply TRMPS-IR to rsEGFP2 and implement a Savitzky-Golay derivative analysis to correct for baseline drift. The results reveal that a subpicosecond twisted excited state precursor controls the trans-to-cis isomerization and the chromophore reaches its final position in the protein pocket within 100 ps. A new step with a time constant of 42 ns is reported and assigned to structural relaxation of the protein that occurs prior to the deprotonation of the chromophore on the millisecond time scale.
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Affiliation(s)
- Lucas M Uriarte
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
| | - Raffaele Vitale
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
| | - Stanisław Niziński
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
- Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, Poznan 61-614, Poland
| | | | - Ninon Zala
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Gregory M Greetham
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, U.K
| | - Igor V Sazanovich
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, U.K
| | - Martin Weik
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Cyril Ruckebusch
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Michel Sliwa
- Univ. Lille, CNRS, UMR 8516, LASIRE, Laboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, Lille 59000, France
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15
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Abstract
Light activated proteins are at the heart of photobiology and optogenetics, so there is wide interest in understanding the mechanisms coupling optical excitation to protein function. In addition, such light activated proteins provide unique insights into the real-time dynamics of protein function. Using pump-probe spectroscopy, the function of a photoactive protein can be initiated by a sub-100 fs pulse of light, allowing subsequent protein dynamics to be probed from femtoseconds to milliseconds and beyond. Among the most interesting photoactive proteins are the blue light using flavin (BLUF) domain proteins, which regulate the response to light of a wide range of bacterial and some euglenoid processes. The photosensing mechanism of BLUF domains has long been a subject of debate. In contrast to other photoactive proteins, the electronic and nuclear structure of the chromophore (flavin) is the same in dark- and light-adapted states. Thus, the driving force for photoactivity is unclear.To address this question requires real-time observation of both chromophore excited state processes and their effect on the structure and dynamics of the surrounding protein matrix. In this Account we describe how time-resolved infrared (IR) experiments, coupled with chemical biology, provide important new insights into the signaling mechanism of BLUF domains. IR measurements are sensitive to changes in both chromophore electronic structure and protein hydrogen bonding interactions. These contributions are resolved by isotope labeling of the chromophore and protein separately. Further, a degree of control over BLUF photochemistry is achieved through mutagenesis, while unnatural amino acid substitution allows us to both fine-tune the photochemistry and time resolve protein dynamics with spatial resolution.Ultrafast studies of BLUF domains reveal non-single-exponential relaxation of the flavin excited state. That relaxation leads within one nanosecond to the original flavin ground state bound in a modified hydrogen-bonding network, as seen in transient and steady-state IR spectroscopy. The change in H-bond configuration arises from formation of an unusual enol (imine) form of a critical glutamine residue. The dynamics observed, complemented by quantum mechanical calculations, suggest a unique sequential electron then double proton transfer reaction as the driving force, followed by rapid reorganization in the binding site and charge recombination. Importantly, studies of several BLUF domains reveal an unexpected diversity in their dynamics, although the underlying structure appears highly conserved. It is suggested that this diversity reflects structural dynamics in the ground state at standard temperature, leading to a distribution of structures and photochemical outcomes. Time resolved IR measurements were extended to the millisecond regime for one BLUF domain, revealing signaling state formation on the microsecond time scale. The mechanism involves reorganization of a β-sheet connected to the chromophore binding pocket via a tryptophan residue. The potential of site-specific labeling amino acids with IR labels as a tool for probing protein structural dynamics was demonstrated.In summary, time-resolved IR studies of BLUF domains (along with related studies at visible wavelengths and quantum and molecular dynamics calculations) have resolved the photoactivation mechanism and real-time dynamics of signaling state formation. These measurements provide new insights into protein structural dynamics and will be important in optimizing the potential of BLUF domains in optobiology.
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Affiliation(s)
- Andras Lukacs
- Department of Biophysics, Medical School, University of Pécs, Szigeti str 12, 7624 Pécs, Hungary
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794-3400, United States
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
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16
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Bressan G, Jirasek M, Roy P, Anderson HL, Meech SR, Heisler IA. Population and Coherence Dynamics in Large Conjugated Porphyrin Nanorings. Chem Sci 2022; 13:9624-9636. [PMID: 36091893 PMCID: PMC9400675 DOI: 10.1039/d2sc01971j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 07/12/2022] [Indexed: 11/28/2022] Open
Abstract
In photosynthesis, nature exploits the distinctive electronic properties of chromophores arranged in supramolecular rings for efficient light harvesting. Among synthetic supramolecular cyclic structures, porphyrin nanorings have attracted considerable attention as they have a resemblance to naturally occurring light-harvesting structures but offer the ability to control ring size and the level of disorder. Here, broadband femtosecond transient absorption spectroscopy, with pump pulses in resonance with either the high or the low energy sides of the inhomogeneously broadened absorption spectrum, is used to study the population dynamics and ground and excited state vibrational coherence in large porphyrin nanorings. A series of fully conjugated, alkyne bridged, nanorings constituted of between ten and forty porphyrin units is studied. Pump-wavelength dependent fast spectral evolution is found. A fast rise or decay of the stimulated emission is found when large porphyrin nanorings are excited on, respectively, the high or low energy side of the absorption spectrum. Such dynamics are consistent with the hypothesis of a variation in transition dipole moment across the inhomogeneously broadened ground state ensemble. The observed dynamics indicate the interplay of nanoring conformation and oscillator strength. Oscillatory dynamics on the sub-ps time domain are observed in both pumping conditions. A combined analysis of the excitation wavelength-dependent transient spectra along with the amplitude and phase evolution of the oscillations allows assignment to vibrational wavepackets evolving on either ground or excited states electronic potential energy surfaces. Even though porphyrin nanorings support highly delocalized electronic wavefunctions, with coherence length spanning tens of chromophores, the measured vibrational coherences remain localised on the monomers. The main contributions to the beatings are assigned to two vibrational modes localised on the porphyrin cores: a Zn–N stretching mode and a skeletal methinic/pyrrolic C–C stretching and in-plane bending mode. Pump wavelength-dependent, ultrafast excited state dynamics arising from inhomogeneous broadening and ground and excited state nuclear wavepackets were observed for a series of Zn porphyrin nanorings made of 10 to 40 repeating units.![]()
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Affiliation(s)
- Giovanni Bressan
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Michael Jirasek
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory Oxford OX1 3TA UK
| | - Palas Roy
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Harry L Anderson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory Oxford OX1 3TA UK
| | - Stephen R Meech
- School of Chemistry Norwich Research Park, University of East Anglia Norwich NR4 7TJ UK
| | - Ismael A Heisler
- Instituto de Física, Universidade Federal do Rio Grande do Sul Avenida Bento Gonçalves, 9500, CEP 91501-970 Porto Alegre Brazil
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17
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Heisler IA, Meech SR. Altered relaxation dynamics of excited state reactions by confinement in reverse micelles probed by ultrafast fluorescence up-conversion. Chem Soc Rev 2021; 50:11486-11502. [PMID: 34661209 DOI: 10.1039/d1cs00516b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Chemical reactions in confined environments are important in areas as diverse as heterogenous catalysis, environmental chemistry and biochemistry, yet they are much less well understood than the equivalent reactions in either the gas phase or in free solution. The understanding of chemical reactions in solution was greatly enhanced by real time studies of model reactions, through ultrafast spectroscopy (especially when supported by molecular dynamics simulation). Here we review some of the efforts that have been made to adapt this approach to the investigation of reactions in confined media. Specifically, we review the application of ultrafast fluorescence spectroscopy to measure reaction dynamics in the nanoconfined water phase of reverse micelles, as a function of the droplet radius and the charge on the interface. Methods of measurement and modelling of the reactions are outlined. In all of the cases studied (which are focused on ultrafast intramolecular reactions) the effect of confinement was to suppress the reaction. Even in the largest micelles the result in the bulk aqueous phase was not usually recovered, suggesting an important role for specific interactions between reactant and environment, for example at the interface. There was no simple one-to-one correspondence with direct measures of the dynamics of the confined phase. Thus, understanding the effect of confinement on reaction rate appears to require not only knowledge of the dynamics of the reaction in solutions and the effect of confinement on the medium, but also of the interaction between reactant and confining medium.
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Affiliation(s)
- Ismael A Heisler
- Departamento de Física, Universidade Federal do Paraná, Curitiba, Paraná, CEP 81531-980, Brazil
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK.
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18
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Coughlan NJA, Stockett MH, Kjær C, Ashworth EK, Bulman Page PC, Meech SR, Brøndsted Nielsen S, Blancafort L, Hopkins WS, Bull JN. Action spectroscopy of the isolated red Kaede fluorescent protein chromophore. J Chem Phys 2021; 155:124304. [PMID: 34598549 DOI: 10.1063/5.0063258] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Incorporation of fluorescent proteins into biochemical systems has revolutionized the field of bioimaging. In a bottom-up approach, understanding the photophysics of fluorescent proteins requires detailed investigations of the light-absorbing chromophore, which can be achieved by studying the chromophore in isolation. This paper reports a photodissociation action spectroscopy study on the deprotonated anion of the red Kaede fluorescent protein chromophore, demonstrating that at least three isomers-assigned to deprotomers-are generated in the gas phase. Deprotomer-selected action spectra are recorded over the S1 ← S0 band using an instrument with differential mobility spectrometry coupled with photodissociation spectroscopy. The spectrum for the principal phenoxide deprotomer spans the 480-660 nm range with a maximum response at ≈610 nm. The imidazolate deprotomer has a blue-shifted action spectrum with a maximum response at ≈545 nm. The action spectra are consistent with excited state coupled-cluster calculations of excitation wavelengths for the deprotomers. A third gas-phase species with a distinct action spectrum is tentatively assigned to an imidazole tautomer of the principal phenoxide deprotomer. This study highlights the need for isomer-selective methods when studying the photophysics of biochromophores possessing several deprotonation sites.
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Affiliation(s)
- Neville J A Coughlan
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000, Denmark
| | - Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Philip C Bulman Page
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Stephen R Meech
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | | | - Lluís Blancafort
- Institut de Química Computacional i Catálisi and Departament de Química, Universitat de Girona, C/M.A. Capmany 69, 17003 Girona, Spain
| | - W Scott Hopkins
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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19
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Green D, Roy P, Hall CR, Iuliano JN, Jones GA, Lukacs A, Tonge PJ, Meech SR. Excited State Resonance Raman of Flavin Mononucleotide: Comparison of Theory and Experiment. J Phys Chem A 2021; 125:6171-6179. [PMID: 34240863 DOI: 10.1021/acs.jpca.1c04063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Blue light absorbing flavoproteins play important roles in a variety of photobiological processes. Consequently, there have been numerous investigations of their excited state structure and dynamics, in particular by time-resolved vibrational spectroscopy. The isoalloxazine chromophore of the flavoprotein cofactors has been studied in detail by time-resolved Raman, lending it a benchmark status for mode assignments in excited electronic states of large molecules. However, detailed comparisons of calculated and measured spectra have proven challenging, as there are many more modes calculated than are observed, and the role of resonance enhancement is difficult to characterize in excited electronic states. Here we employ a recently developed approach due to Elles and co-workers ( J. Phys. Chem. A 2018, 122, 8308-8319) for the calculation of resonance-enhanced Raman spectra of excited states and apply it to the lowest singlet and triplet excited states of the isoalloxazine chromophore. There is generally good agreement between calculated and observed enhancements, which allows assignment of vibrational bands of the flavoprotein cofactors to be refined. However, some prominently enhanced bands are found to be absent from the calculations, suggesting the need for further development of the theory.
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Affiliation(s)
- Dale Green
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Palas Roy
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | | | - James N Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Garth A Jones
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
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20
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Roy P, Bressan G, Gretton J, Cammidge AN, Meech SR. Ultrafast Excimer Formation and Solvent Controlled Symmetry Breaking Charge Separation in the Excitonically Coupled Subphthalocyanine Dimer. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Palas Roy
- School of Chemistry University of East Anglia Nowich NR4 7TJ UK
| | - Giovanni Bressan
- Department of Life Sciences Imperial College London London SW7 2BX UK
| | - Jacob Gretton
- School of Chemistry University of East Anglia Nowich NR4 7TJ UK
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21
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Roy P, Sardjan AS, Cnossen A, Browne WR, Feringa BL, Meech SR. Excited State Structure Correlates with Efficient Photoconversion in Unidirectional Motors. J Phys Chem Lett 2021; 12:3367-3372. [PMID: 33784091 DOI: 10.1021/acs.jpclett.1c00710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The design of unidirectional photomolecular motors demands a critical understanding of an ultrafast photochemical isomerization. An intermediate dark excited state mediates the reaction via a conical intersection (CI) with the ground state, but a correlation between molecular structure and photoisomerization efficiency has remained elusive. Here femtosecond stimulated Raman spectroscopy captures vibrational spectra of the dark state in a set of molecular motors bearing different substituents. A direct correlation between isomerization quantum yield, dark state lifetime, and excited state vibrational spectrum is found. Electron withdrawing substituents lead to activity in lower frequency modes, which we correlate with a pyramidalization distortion at the ethylenic axle occurring within 100 fs. This structure is not formed with an electron donating substituent, where the axle retains double bond character. Further structural reorganization is observed and assigned to excited state reorganization and charge redistribution on the sub-picosecond time scale. The correlation of the dark state structure with photoconversion performance suggests guidelines for developing new more efficient motor derivatives.
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Affiliation(s)
- Palas Roy
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Andy S Sardjan
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Arjen Cnossen
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Wesley R Browne
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Ben L Feringa
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
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22
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Roy P, Bressan G, Gretton J, Cammidge AN, Meech SR. Ultrafast Excimer Formation and Solvent Controlled Symmetry Breaking Charge Separation in the Excitonically Coupled Subphthalocyanine Dimer. Angew Chem Int Ed Engl 2021; 60:10568-10572. [PMID: 33606913 PMCID: PMC8251754 DOI: 10.1002/anie.202101572] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Indexed: 11/18/2022]
Abstract
Knowledge of the factors controlling excited state dynamics in excitonically coupled dimers and higher aggregates is critical for understanding natural and artificial solar energy conversion. In this work, we report ultrafast solvent polarity dependent excited state dynamics of the structurally well‐defined subphthalocyanine dimer, μ‐OSubPc2. Stationary electronic spectra demonstrate strong exciton coupling in μ‐OSubPc2. Femtosecond transient absorption measurements reveal ultrafast excimer formation from the initially excited exciton, mediated by intramolecular structural evolution. In polar solvents the excimer state decays directly through symmetry breaking charge transfer to form a charge separated state. Charge separation occurs under control of solvent orientational relaxation.
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Affiliation(s)
- Palas Roy
- School of Chemistry, University of East Anglia, Nowich, NR4 7TJ, UK
| | - Giovanni Bressan
- Department of Life Sciences, Imperial College London, London, SW7 2BX, UK
| | - Jacob Gretton
- School of Chemistry, University of East Anglia, Nowich, NR4 7TJ, UK
| | | | - Stephen R Meech
- School of Chemistry, University of East Anglia, Nowich, NR4 7TJ, UK
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23
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Roy P, Sardjan AS, Danowski W, Browne WR, Feringa BL, Meech SR. Photophysics of First-Generation Photomolecular Motors: Resolving Roles of Temperature, Friction, and Medium Polarity. J Phys Chem A 2021; 125:1711-1719. [PMID: 33606528 DOI: 10.1021/acs.jpca.0c11050] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Light-driven unidirectional molecular rotary motors have the potential to power molecular machines. Consequently, optimizing their speed and efficiency is an important objective. Here, we investigate factors controlling the photochemical yield of the prototypical unidirectional rotary motor, a sterically overcrowded alkene, through detailed investigation of its excited-state dynamics. An isoviscosity analysis of the ultrafast fluorescence decay data resolves friction from barrier effects and reveals a 3.4 ± 0.5 kJ mol-1 barrier to excited-state decay in nonpolar media. Extension of this analysis to polar solvents shows that this barrier height is a strong function of medium polarity and that the decay pathway becomes near barrierless in more polar media. Thus, the properties of the medium can be used as a route for controlling the motor's excited-state dynamics. The connection between these dynamics and the quantum yield of photochemical isomerization is probed. The photochemical quantum yield is shown to be a much weaker function of solvent polarity, and the most efficient excited-state decay pathway does not lead to a strongly enhanced quantum yield for isomerization. These results are discussed in terms of the solvent dependence of the complex multidimensional excited-state reaction coordinate.
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Affiliation(s)
- Palas Roy
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Andy S Sardjan
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Wojciech Danowski
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Wesley R Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Ben L Feringa
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
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24
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Pirisi K, Nag L, Fekete Z, Iuliano JN, Tolentino Collado J, Clark IP, Pécsi I, Sournia P, Liebl U, Greetham GM, Tonge PJ, Meech SR, Vos MH, Lukacs A. Identification of the vibrational marker of tyrosine cation radical using ultrafast transient infrared spectroscopy of flavoprotein systems. Photochem Photobiol Sci 2021; 20:369-378. [PMID: 33721272 DOI: 10.1007/s43630-021-00024-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/09/2021] [Indexed: 11/29/2022]
Abstract
Tryptophan and tyrosine radical intermediates play crucial roles in many biological charge transfer processes. Particularly in flavoprotein photochemistry, short-lived reaction intermediates can be studied by the complementary techniques of ultrafast visible and infrared spectroscopy. The spectral properties of tryptophan radical are well established, and the formation of neutral tyrosine radicals has been observed in many biological processes. However, only recently, the formation of a cation tyrosine radical was observed by transient visible spectroscopy in a few systems. Here, we assigned the infrared vibrational markers of the cationic and neutral tyrosine radical at 1483 and 1502 cm-1 (in deuterated buffer), respectively, in a variant of the bacterial methyl transferase TrmFO, and in the native glucose oxidase. In addition, we studied a mutant of AppABLUF blue-light sensor domain from Rhodobacter sphaeroides in which only a direct formation of the neutral radical was observed. Our studies highlight the exquisite sensitivity of transient infrared spectroscopy to low concentrations of specific radicals.
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Affiliation(s)
- Katalin Pirisi
- Department of Biophysics, Medical School, University of Pecs, Szigeti Str. 12, 7624, Pecs, Hungary
| | - Lipsa Nag
- Laboratoire d'Optique et Biosciences, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Zsuzsanna Fekete
- Department of Biophysics, Medical School, University of Pecs, Szigeti Str. 12, 7624, Pecs, Hungary
| | - James N Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA
| | | | - Ian P Clark
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0QX, Oxon, UK
| | - Ildikó Pécsi
- Department of Biophysics, Medical School, University of Pecs, Szigeti Str. 12, 7624, Pecs, Hungary
| | - Pierre Sournia
- Laboratoire d'Optique et Biosciences, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Ursula Liebl
- Laboratoire d'Optique et Biosciences, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Gregory M Greetham
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, OX11 0QX, Oxon, UK
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Marten H Vos
- Laboratoire d'Optique et Biosciences, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France.
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti Str. 12, 7624, Pecs, Hungary.
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25
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Iuliano JN, Collado JT, Gil AA, Ravindran PT, Lukacs A, Shin S, Woroniecka HA, Adamczyk K, Aramini JM, Edupuganti UR, Hall CR, Greetham GM, Sazanovich IV, Clark IP, Daryaee T, Toettcher JE, French JB, Gardner KH, Simmerling CL, Meech SR, Tonge PJ. Unraveling the Mechanism of a LOV Domain Optogenetic Sensor: A Glutamine Lever Induces Unfolding of the Jα Helix. ACS Chem Biol 2020; 15:2752-2765. [PMID: 32880430 DOI: 10.1021/acschembio.0c00543] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Light-activated protein domains provide a convenient, modular, and genetically encodable sensor for optogenetics and optobiology. Although these domains have now been deployed in numerous systems, the precise mechanism of photoactivation and the accompanying structural dynamics that modulate output domain activity remain to be fully elucidated. In the C-terminal light-oxygen-voltage (LOV) domain of plant phototropins (LOV2), blue light activation leads to formation of an adduct between a conserved Cys residue and the embedded FMN chromophore, rotation of a conserved Gln (Q513), and unfolding of a helix (Jα-helix) which is coupled to the output domain. In the present work, we focus on the allosteric pathways leading to Jα helix unfolding in Avena sativa LOV2 (AsLOV2) using an interdisciplinary approach involving molecular dynamics simulations extending to 7 μs, time-resolved infrared spectroscopy, solution NMR spectroscopy, and in-cell optogenetic experiments. In the dark state, the side chain of N414 is hydrogen bonded to the backbone N-H of Q513. The simulations predict a lever-like motion of Q513 after Cys adduct formation resulting in a loss of the interaction between the side chain of N414 and the backbone C═O of Q513, and formation of a transient hydrogen bond between the Q513 and N414 side chains. The central role of N414 in signal transduction was evaluated by site-directed mutagenesis supporting a direct link between Jα helix unfolding dynamics and the cellular function of the Zdk2-AsLOV2 optogenetic construct. Through this multifaceted approach, we show that Q513 and N414 are critical mediators of protein structural dynamics, linking the ultrafast (sub-ps) excitation of the FMN chromophore to the microsecond conformational changes that result in photoreceptor activation and biological function.
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Affiliation(s)
- James N. Iuliano
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | | | - Agnieszka A. Gil
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
| | - Pavithran T. Ravindran
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
| | - Andras Lukacs
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
- Department of Biophysics, Medical School, University of Pecs, Szigeti út 12, 7624 Pecs, Hungary
| | - SeungYoun Shin
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | | | - Katrin Adamczyk
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - James M. Aramini
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, New York 10031, United States
| | - Uthama R. Edupuganti
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, New York 10031, United States
- Ph.D. Program in Biochemistry, CUNY Graduate Center, New York, New York, United States
| | - Christopher R. Hall
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - Gregory M. Greetham
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom
| | - Igor V. Sazanovich
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom
| | - Ian P. Clark
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom
| | - Taraneh Daryaee
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Jared E. Toettcher
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
| | - Jarrod B. French
- Department of Chemistry, Stony Brook University, New York, 11794, United States
- Hormel Institute, University of Minnesota, Austin, Minnesota 55912, United States
| | - Kevin H. Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center, 85 St. Nicholas Terrace, New York, New York 10031, United States
- Ph.D. Programs in Biochemistry, Biology, and Chemistry, CUNY Graduate Center, New York, New York, United States
- Department of Chemistry and Biochemistry, City College of New York, New York, New York, United States
| | | | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, United Kingdom
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, New York, 11794, United States
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26
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Iuliano JN, Hall CR, Green D, Jones GA, Lukacs A, Illarionov B, Bacher A, Fischer M, French JB, Tonge PJ, Meech SR. Excited State Vibrations of Isotopically Labeled FMN Free and Bound to a Light-Oxygen-Voltage (LOV) Protein. J Phys Chem B 2020; 124:7152-7165. [PMID: 32786715 PMCID: PMC7533957 DOI: 10.1021/acs.jpcb.0c04943] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Flavoproteins are important blue light sensors in photobiology and play a key role in optogenetics. The characterization of their excited state structure and dynamics is thus an important objective. Here, we present a detailed study of excited state vibrational spectra of flavin mononucleotide (FMN), in solution and bound to the LOV-2 (Light-Oxygen-Voltage) domain of Avena sativa phototropin. Vibrational frequencies are determined for the optically excited singlet state and the reactive triplet state, through resonant ultrafast femtosecond stimulated Raman spectroscopy (FSRS). To assign the observed spectra, vibrational frequencies of the excited states are calculated using density functional theory, and both measurement and theory are applied to four different isotopologues of FMN. Excited state mode assignments are refined in both states, and their sensitivity to deuteration and protein environment are investigated. We show that resonant FSRS provides a useful tool for characterizing photoactive flavoproteins and is able to highlight chromophore localized modes and to record hydrogen/deuterium exchange.
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Affiliation(s)
- James N. Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | | | - Dale Green
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Garth A. Jones
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Boris Illarionov
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Adelbert Bacher
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
- Department of Chemistry, Technical University of Munich, 85747 Garching, Germany
| | - Markus Fischer
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Jarrod B. French
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
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27
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Sardjan AS, Roy P, Danowski W, Bressan G, Nunes dos Santos Comprido L, Browne WR, Feringa BL, Meech SR. Cover Feature: Ultrafast Excited State Dynamics in a First Generation Photomolecular Motor (ChemPhysChem 7/2020). Chemphyschem 2020. [DOI: 10.1002/cphc.202000179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Andy S. Sardjan
- Molecular Inorganic Chemistry Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 4 9747AG Groningen The Netherlands
| | - Palas Roy
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Wojciech Danowski
- Synthetic Organic Chemistry Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 4 9747AG Groningen The Netherlands
| | - Giovanni Bressan
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
| | - Laura Nunes dos Santos Comprido
- Molecular Inorganic Chemistry Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 4 9747AG Groningen The Netherlands
| | - Wesley R. Browne
- Molecular Inorganic Chemistry Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 4 9747AG Groningen The Netherlands
| | - Ben. L. Feringa
- Synthetic Organic Chemistry Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 4 9747AG Groningen The Netherlands
| | - Stephen R. Meech
- School of ChemistryUniversity of East Anglia Norwich Research Park Norwich NR4 7TJ UK
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28
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Sardjan AS, Roy P, Danowski W, Bressan G, Nunes Dos Santos Comprido L, Browne WR, Feringa BL, Meech SR. Ultrafast Excited State Dynamics in a First Generation Photomolecular Motor. Chemphyschem 2020; 21:594-599. [PMID: 31975490 PMCID: PMC7187380 DOI: 10.1002/cphc.201901179] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/17/2020] [Indexed: 12/13/2022]
Abstract
Efficient photomolecular motors will be critical elements in the design and development of molecular machines. Optimisation of the quantum yield for photoisomerisation requires a detailed understanding of molecular dynamics in the excited electronic state. Here we probe the primary photophysical processes in the archetypal first generation photomolecular motor, with sub‐50 fs time resolved fluorescence spectroscopy. A bimodal relaxation is observed with a 100 fs relaxation of the Franck‐Condon state to populate a red‐shifted state with a reduced transition moment, which then undergoes multi‐exponential decay on a picosecond timescale. Oscillations due to the excitation of vibrational coherences in the S1 state are seen to survive the ultrafast structural relaxation. The picosecond relaxation reveals a strong solvent friction effect which is thus ascribed to torsion about the C−C axle. This behaviour is contrasted with second generation photomolecular motors; the principal differences are explained by the existence of a barrier on the excited state surface in the case of the first‐generation motors which is absent in the second generation. These results will help to provide a basis for designing more efficient molecular motors in the future.
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Affiliation(s)
- Andy S Sardjan
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Palas Roy
- School of Chemistry, University of East Anglia Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Wojciech Danowski
- Synthetic Organic Chemistry Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Giovanni Bressan
- School of Chemistry, University of East Anglia Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Laura Nunes Dos Santos Comprido
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Wesley R Browne
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Ben L Feringa
- Synthetic Organic Chemistry Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Stephen R Meech
- School of Chemistry, University of East Anglia Norwich Research Park, Norwich, NR4 7TJ, UK
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29
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Karadi K, Kapetanaki SM, Raics K, Pecsi I, Kapronczai R, Fekete Z, Iuliano JN, Collado JT, Gil AA, Orban J, Nyitrai M, Greetham GM, Vos MH, Tonge PJ, Meech SR, Lukacs A. Functional dynamics of a single tryptophan residue in a BLUF protein revealed by fluorescence spectroscopy. Sci Rep 2020; 10:2061. [PMID: 32029866 PMCID: PMC7005313 DOI: 10.1038/s41598-020-59073-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 01/23/2020] [Indexed: 11/17/2022] Open
Abstract
Blue Light Using Flavin (BLUF) domains are increasingly being adopted for use in optogenetic constructs. Despite this, much remains to be resolved on the mechanism of their activation. The advent of unnatural amino acid mutagenesis opens up a new toolbox for the study of protein structural dynamics. The tryptophan analogue, 7-aza-Trp (7AW) was incorporated in the BLUF domain of the Activation of Photopigment and pucA (AppA) photoreceptor in order to investigate the functional dynamics of the crucial W104 residue during photoactivation of the protein. The 7-aza modification to Trp makes selective excitation possible using 310 nm excitation and 380 nm emission, separating the signals of interest from other Trp and Tyr residues. We used Förster energy transfer (FRET) between 7AW and the flavin to estimate the distance between Trp and flavin in both the light- and dark-adapted states in solution. Nanosecond fluorescence anisotropy decay and picosecond fluorescence lifetime measurements for the flavin revealed a rather dynamic picture for the tryptophan residue. In the dark-adapted state, the major population of W104 is pointing away from the flavin and can move freely, in contrast to previous results reported in the literature. Upon blue-light excitation, the dominant tryptophan population is reorganized, moves closer to the flavin occupying a rigidly bound state participating in the hydrogen-bond network around the flavin molecule.
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Affiliation(s)
- Kristof Karadi
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary.,Szentagothai Research Center, University of Pécs, 7624, Pécs, Hungary
| | - Sofia M Kapetanaki
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary.,Szentagothai Research Center, University of Pécs, 7624, Pécs, Hungary
| | - Katalin Raics
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary
| | - Ildiko Pecsi
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary
| | - Robert Kapronczai
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary
| | - Zsuzsanna Fekete
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary
| | - James N Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA
| | | | - Agnieszka A Gil
- Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA
| | - Jozsef Orban
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary
| | - Miklos Nyitrai
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary.,Szentagothai Research Center, University of Pécs, 7624, Pécs, Hungary
| | - Greg M Greetham
- Central Laser Facility, Harwell Science and Innovation Campus, Didcot, Oxfordshire, UK
| | - Marten H Vos
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, Cedex, France
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400, USA
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pécs, 7624, Pécs, Hungary. .,Szentagothai Research Center, University of Pécs, 7624, Pécs, Hungary.
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30
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Lukacs A, Tolentino J, Iuliano J, Pirisi K, Tonge PJ, Greetham G, Towrie M, Meech SR. Radical Formation in the Photoactivated Adenylate Cyclase OaPAC Revealed by Ultrafast Spectroscopy. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.3285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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31
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Hall CR, Tolentino Collado J, Iuliano JN, Gil AA, Adamczyk K, Lukacs A, Greetham GM, Sazanovich I, Tonge PJ, Meech SR. Site-Specific Protein Dynamics Probed by Ultrafast Infrared Spectroscopy of a Noncanonical Amino Acid. J Phys Chem B 2019; 123:9592-9597. [DOI: 10.1021/acs.jpcb.9b09425] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - James N. Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Agnieszka A. Gil
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Katrin Adamczyk
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Gregory M. Greetham
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, U.K
| | - Igor Sazanovich
- Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0QX, U.K
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
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32
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van Wonderen JH, Hall CR, Jiang X, Adamczyk K, Carof A, Heisler I, Piper SEH, Clarke TA, Watmough NJ, Sazanovich IV, Towrie M, Meech SR, Blumberger J, Butt JN. Ultrafast Light-Driven Electron Transfer in a Ru(II)tris(bipyridine)-Labeled Multiheme Cytochrome. J Am Chem Soc 2019; 141:15190-15200. [DOI: 10.1021/jacs.9b06858] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jessica H. van Wonderen
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Christopher R. Hall
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Xiuyun Jiang
- Department of Physics and Astronomy and Thomas-Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - Katrin Adamczyk
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Antoine Carof
- Department of Physics and Astronomy and Thomas-Young Centre, University College London, London WC1E 6BT, United Kingdom
| | - Ismael Heisler
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Samuel E. H. Piper
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Thomas A. Clarke
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Nicholas J. Watmough
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Igor V. Sazanovich
- Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot, Oxon OX11 0QX, United Kingdom
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell, Harwell Campus, Didcot, Oxon OX11 0QX, United Kingdom
| | - Stephen R. Meech
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Jochen Blumberger
- Department of Physics and Astronomy and Thomas-Young Centre, University College London, London WC1E 6BT, United Kingdom
- Institute for Advanced Study, Technische Universität München, Lichtenbergstrasse 2 a, D-85748 Garching, Germany
| | - Julea N. Butt
- School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
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Bressan G, Cammidge AN, Jones GA, Heisler IA, Gonzalez-Lucas D, Remiro-Buenamañana S, Meech SR. Electronic Energy Transfer in a Subphthalocyanine-Zn Porphyrin Dimer Studied by Linear and Nonlinear Ultrafast Spectroscopy. J Phys Chem A 2019; 123:5724-5733. [PMID: 31257894 DOI: 10.1021/acs.jpca.9b04398] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The efficient harvesting and transport of visible light by electronic energy transfer (EET) are critical to solar energy conversion in both nature and molecular electronics. In this work, we study EET in a synthetic dyad comprising a visible absorbing subphthalocyanine (SubPc) donor and a Zn tetraphenyl porphyrin (ZnTPP) acceptor. Energy transfer is probed by steady-state spectroscopy, ultrafast transient absorption, and two-dimensional electronic spectroscopy. Steady-state and time-resolved experiments point to only weak electronic coupling between the components of the dimer. The weak coupling supports energy transfer from the SubPc to the zinc porphyrin in 7 ps, which itself subsequently undergoes intersystem crossing to populate the triplet state. The rate of the forward energy transfer is discussed in terms of the structure of the dimer, which is calculated by density functional theory. There is evidence of back energy transfer from the ZnTPP on the hundreds of picoseconds time scale. Sub-picosecond spectral diffusion was also observed and characterized, but it does not influence the picosecond energy transfer.
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Affiliation(s)
- Giovanni Bressan
- School of Chemistry , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Andrew N Cammidge
- School of Chemistry , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Garth A Jones
- School of Chemistry , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Ismael A Heisler
- Departamento de Física , Universidade Federal do Paraná , Caixa Postal 19044 , 81531-990 Curitiba , Parana , Brazil
| | | | | | - Stephen R Meech
- School of Chemistry , University of East Anglia , Norwich NR4 7TJ , United Kingdom
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34
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Bressan G, Green D, Chan Y, Bulman Page PC, Jones GA, Meech SR, Heisler IA. One- to Two-Exciton Transitions in Perylene Bisimide Dimer Revealed by Two-Dimensional Electronic Spectroscopy. J Phys Chem A 2018; 123:1594-1601. [PMID: 30516984 DOI: 10.1021/acs.jpca.8b11473] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The excited-state energy levels of molecular dimers and aggregates play a critical role in their photophysical behavior and an understanding of the photodynamics in such structures is important for developing applications such as photovoltaics and optoelectronic devices. Here, exciton transitions in two different covalently bound PBI dimers are studied by two-dimensional electronic spectroscopy (2DES), a powerful spectroscopic method, providing the most complete picture of vibronic transitions in molecular systems. The data are accurately reproduced using the equation of motion-phase matching approach. The unambiguous presence of one-exciton to two-exciton transitions are captured in our results and described in terms of a molecular exciton energy level scheme based on the Kasha model. Furthermore, the results are supported by comparative measurements with the PBI monomer and another dimer in which the interchromophore distance is increased.
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Affiliation(s)
- Giovanni Bressan
- School of Chemistry, Norwich Research Park , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Dale Green
- School of Chemistry, Norwich Research Park , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Yohan Chan
- School of Chemistry, Norwich Research Park , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Philip C Bulman Page
- School of Chemistry, Norwich Research Park , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Garth A Jones
- School of Chemistry, Norwich Research Park , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Stephen R Meech
- School of Chemistry, Norwich Research Park , University of East Anglia , Norwich NR4 7TJ , United Kingdom
| | - Ismael A Heisler
- Departamento de Física , Universidade Federal do Paraná , Caixa Postal 19044, 81531-990 Curitiba , Parana , Brazil
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35
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Hall CR, Romanov AS, Bochmann M, Meech SR. Ultrafast Structure and Dynamics in the Thermally Activated Delayed Fluorescence of a Carbene-Metal-Amide. J Phys Chem Lett 2018; 9:5873-5876. [PMID: 30230847 DOI: 10.1021/acs.jpclett.8b02797] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Thermally activated delayed fluorescence has enormous potential for the development of efficient light emitting diodes. A recently discovered class of molecules (the carbene-metal-amides, CMAs) are exceptionally promising as they combine the small singlet-triplet energy gap required for thermal activation with a large transition moment for emission. Calculations suggest excited state structural dynamics modulate the critical coupling between singlet and triplet, but they disagree on the nature of those dynamics. Here we report ultrafast time-resolved transient absorption and Raman studies of CMA photodynamics. The measurements reveal complex structural evolution following intersystem crossing on the tens to hundreds of picoseconds time scale, and a change in the low-frequency vibrational spectrum between singlet and triplet states. The latter is assigned to changes in Raman active modes localized on the metal center.
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Affiliation(s)
| | | | - Manfred Bochmann
- School of Chemistry , University of East Anglia , Norwich NR4 7TJ , U.K
| | - Stephen R Meech
- School of Chemistry , University of East Anglia , Norwich NR4 7TJ , U.K
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36
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Laptenok SP, Gil AA, Hall CR, Lukacs A, Iuliano JN, Jones GA, Greetham GM, Donaldson P, Miyawaki A, Tonge PJ, Meech SR. Infrared spectroscopy reveals multi-step multi-timescale photoactivation in the photoconvertible protein archetype dronpa. Nat Chem 2018; 10:845-852. [PMID: 29892029 DOI: 10.1038/s41557-018-0073-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 04/27/2018] [Indexed: 01/13/2023]
Abstract
Photochromic fluorescent proteins play key roles in super-resolution microscopy and optogenetics. The light-driven structural changes that modulate the fluorescence involve both trans-to-cis isomerization and proton transfer. The mechanism, timescale and relative contribution of chromophore and protein dynamics are currently not well understood. Here, the mechanism of off-to-on-state switching in dronpa is studied using femtosecond-to-millisecond time-resolved infrared spectroscopy and isotope labelling. Chromophore and protein dynamics are shown to occur on multiple timescales, from picoseconds to hundreds of microseconds. Following excitation of the trans chromophore, a ground-state primary product is formed within picoseconds. Surprisingly, the characteristic vibrational spectrum of the neutral cis isomer appears only after several tens of nanoseconds. Further fluctuations in protein structure around the neutral cis chromophore are required to form a new intermediate, which promotes the final proton-transfer reaction. These data illustrate the interplay between chromophore dynamics and the protein environment underlying fluorescent protein photochromism.
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Affiliation(s)
- Sergey P Laptenok
- School of Chemistry, University of East Anglia, Norwich, UK.,Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Agnieszka A Gil
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Christopher R Hall
- School of Chemistry, University of East Anglia, Norwich, UK.,ARC Centre of Excellence in Exciton Science, School of Chemistry, The University of Melbourne, Parkville, Victoria, Australia
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Pecs, Hungary
| | - James N Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA
| | - Garth A Jones
- School of Chemistry, University of East Anglia, Norwich, UK
| | - Gregory M Greetham
- Central Laser Facility, Harwell Science and Innovation Campus, Didcot, Oxfordshire, UK
| | - Paul Donaldson
- Central Laser Facility, Harwell Science and Innovation Campus, Didcot, Oxfordshire, UK
| | - Atsushi Miyawaki
- Laboratory for Cell Function Dynamics, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, NY, USA.
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich, UK.
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37
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38
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Hall CR, Browne WR, Feringa BL, Meech SR. Mapping the Excited‐State Potential Energy Surface of a Photomolecular Motor. Angew Chem Int Ed Engl 2018; 57:6203-6207. [DOI: 10.1002/anie.201802126] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Indexed: 01/05/2023]
Affiliation(s)
| | - Wesley R. Browne
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry University of Groningen Nijenborgh 4 9747 AG Groningen Netherlands
| | - Ben L. Feringa
- Synthetic Organic Chemistry Stratingh Institute for Chemistry University of Groningen Nijenborgh 4 9747 AG Groningen Netherlands
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39
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Affiliation(s)
| | - Wesley R. Browne
- Molecular Inorganic Chemistry Stratingh Institute for Chemistry University of Groningen Nijenborgh 4 9747 AG Groningen Netherlands
| | - Ben L. Feringa
- Synthetic Organic Chemistry Stratingh Institute for Chemistry University of Groningen Nijenborgh 4 9747 AG Groningen Netherlands
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40
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Iuliano JN, Gil AA, Laptenok SP, Hall CR, Collado JT, Lukacs A, Hag Ahmed SA, Abyad J, Daryaee T, Greetham GM, Sazanovich IV, Illarionov B, Bacher A, Fischer M, Towrie M, French JB, Meech SR, Tonge PJ. Variation in LOV Photoreceptor Activation Dynamics Probed by Time-Resolved Infrared Spectroscopy. Biochemistry 2018; 57:620-630. [PMID: 29239168 PMCID: PMC5801046 DOI: 10.1021/acs.biochem.7b01040] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The light, oxygen, voltage (LOV) domain proteins are blue light photoreceptors that utilize a noncovalently bound flavin mononucleotide (FMN) cofactor as the chromophore. The modular nature of these proteins has led to their wide adoption in the emerging fields of optogenetics and optobiology, where the LOV domain has been fused to a variety of output domains leading to novel light-controlled applications. In this work, we extend our studies of the subpicosecond to several hundred microsecond transient infrared spectroscopy of the isolated LOV domain AsLOV2 to three full-length photoreceptors in which the LOV domain is fused to an output domain: the LOV-STAS protein, YtvA, the LOV-HTH transcription factor, EL222, and the LOV-histidine kinase, LovK. Despite differences in tertiary structure, the overall pathway leading to cysteine adduct formation from the FMN triplet state is highly conserved, although there are slight variations in rate. However, significant differences are observed in the vibrational spectra and kinetics after adduct formation, which are directly linked to the specific output function of the LOV domain. While the rate of adduct formation varies by only 3.6-fold among the proteins, the subsequent large-scale structural changes in the full-length LOV photoreceptors occur over the micro- to submillisecond time scales and vary by orders of magnitude depending on the different output function of each LOV domain.
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Affiliation(s)
- James N. Iuliano
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Agnieszka A. Gil
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | | | | | | | - Andras Lukacs
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K
- Department of Biophysics, Medical School, University of Pecs, Szigeti út 12, 7624 Pecs, Hungary
| | - Safaa A. Hag Ahmed
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Jenna Abyad
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Taraneh Daryaee
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Gregory M. Greetham
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Igor V. Sazanovich
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Boris Illarionov
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Adelbert Bacher
- Department Chemie, Technische Universität München, D-85747 Garching, Germany
| | - Markus Fischer
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Jarrod B. French
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, New York, 11794, United States
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41
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Conyard J, Heisler IA, Chan Y, Bulman Page PC, Meech SR, Blancafort L. A new twist in the photophysics of the GFP chromophore: a volume-conserving molecular torsion couple. Chem Sci 2018; 9:1803-1812. [PMID: 29675225 PMCID: PMC5892128 DOI: 10.1039/c7sc04091a] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 12/30/2017] [Indexed: 01/19/2023] Open
Abstract
Dynamics of a nonplanar GFP chromophore are studied experimentally and theoretically. Coupled torsional motion is responsible for the ultrafast decay.
The simple structure of the chromophore of the green fluorescent protein (GFP), a phenol and an imidazolone ring linked by a methyne bridge, supports an exceptionally diverse range of excited state phenomena. Here we describe experimentally and theoretically the photochemistry of a novel sterically crowded nonplanar derivative of the GFP chromophore. It undergoes an excited state isomerization reaction accompanied by an exceptionally fast (sub 100 fs) excited state decay. The decay dynamics are essentially independent of solvent polarity and viscosity. Excited state structural dynamics are probed by high level quantum chemical calculations revealing that the fast decay is due to a conical intersection characterized by a twist of the rings and pyramidalization of the methyne bridge carbon. The intersection can be accessed without a barrier from the pre-twisted Franck–Condon structure, and the lack of viscosity dependence is due to the fact that the rings twist in the same direction, giving rise to a volume-conserving decay coordinate. Moreover, the rotation of the phenyl, methyl and imidazolone groups is coupled in the sterically crowded structure, with the methyl group translating the rotation of one ring to the next. As a consequence, the excited state dynamics can be viewed as a torsional couple, where the absorbed photon energy leads to conversion of the out-of-plane orientation from one ring to the other in a volume conserving fashion. A similar modification of the range of methyne dyes may provide a new family of devices for molecular machines, specifically torsional couples.
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Affiliation(s)
- Jamie Conyard
- School of Chemistry , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , UK .
| | - Ismael A Heisler
- School of Chemistry , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , UK .
| | - Yohan Chan
- School of Chemistry , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , UK .
| | - Philip C Bulman Page
- School of Chemistry , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , UK .
| | - Stephen R Meech
- School of Chemistry , University of East Anglia , Norwich Research Park , Norwich NR4 7TJ , UK .
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi , Departament de Química , Facultat de Ciències , Universitat de Girona , C/ M. A. Capmany 69 , 17003 Girona , Spain .
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42
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Gil AA, Laptenok SP, Iuliano JN, Lukacs A, Verma A, Hall CR, Yoon GE, Brust R, Greetham GM, Towrie M, French JB, Meech SR, Tonge PJ. Photoactivation of the BLUF Protein PixD Probed by the Site-Specific Incorporation of Fluorotyrosine Residues. J Am Chem Soc 2017; 139:14638-14648. [PMID: 28876066 DOI: 10.1021/jacs.7b07849] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The flavin chromophore in blue-light-using FAD (BLUF) photoreceptors is surrounded by a hydrogen bond network that senses and responds to changes in the electronic structure of the flavin on the ultrafast time scale. The hydrogen bond network includes a strictly conserved Tyr residue, and previously we explored the role of this residue, Y21, in the photoactivation mechanism of the BLUF protein AppABLUF by the introduction of fluorotyrosine (F-Tyr) analogues that modulated the pKa and reduction potential of Y21 by 3.5 pH units and 200 mV, respectively. Although little impact on the forward (dark- to light-adapted form) photoreaction was observed, the change in Y21 pKa led to a 4000-fold increase in the rate of dark-state recovery. In the present work we have extended these studies to the BLUF protein PixD, where, in contrast to AppABLUF, modulation in the Tyr (Y8) pKa has a profound impact on the forward photoreaction. In particular, a decrease in Y8 pKa by 2 or more pH units prevents formation of a stable light state, consistent with a photoactivation mechanism that involves proton transfer or proton-coupled electron transfer from Y8 to the electronically excited FAD. Conversely, the effect of pKa on the rate of dark recovery is markedly reduced in PixD. These observations highlight very significant differences between the photocycles of PixD and AppABLUF, despite their sharing highly conserved FAD binding architectures.
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Affiliation(s)
| | - Sergey P Laptenok
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | | | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs , Pecs H-7622, Hungary
| | - Anil Verma
- Central Laser Facility, Harwell Science and Innovation Campus , Didcot, Oxon OX11 0QX, U.K
| | - Christopher R Hall
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | | | | | - Gregory M Greetham
- Central Laser Facility, Harwell Science and Innovation Campus , Didcot, Oxon OX11 0QX, U.K
| | - Michael Towrie
- Central Laser Facility, Harwell Science and Innovation Campus , Didcot, Oxon OX11 0QX, U.K
| | | | - Stephen R Meech
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
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43
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Hall CR, Heisler IA, Jones GA, Frost JE, Gil AA, Tonge PJ, Meech SR. Femtosecond stimulated Raman study of the photoactive flavoprotein AppABLUF. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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44
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Hall CR, Conyard J, Heisler IA, Jones G, Frost J, Browne WR, Feringa BL, Meech SR. Ultrafast Dynamics in Light-Driven Molecular Rotary Motors Probed by Femtosecond Stimulated Raman Spectroscopy. J Am Chem Soc 2017; 139:7408-7414. [PMID: 28486804 DOI: 10.1021/jacs.7b03599] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photochemical isomerization in sterically crowded chiral alkenes is the driving force for molecular rotary motors in nanoscale machines. Here the excited-state dynamics and structural evolution of the prototypical light-driven rotary motor are followed on the ultrafast time scale by femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption (TA). TA reveals a sub-100-fs blue shift and decay of the Franck-Condon bright state arising from relaxation along the reactive potential energy surface. The decay is accompanied by coherently excited vibrational dynamics which survive the excited-state structural evolution. The ultrafast Franck-Condon bright state relaxes to a dark excited state, which FSRS reveals to have a rich spectrum compared to the electronic ground state, with the most intense Raman-active modes shifted to significantly lower wavenumber. This is discussed in terms of a reduced bond order of the central bridging bond and overall weakening of bonds in the dark state, which is supported by electronic structure calculations. The observed evolution in the FSRS spectrum is assigned to vibrational cooling accompanied by partitioning of the dark state between the product isomer and the original ground state. Formation of the product isomer is observed in real time by FSRS. It is formed vibrationally hot and cools over several picoseconds, completing the characterization of the light-driven half of the photocycle.
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Affiliation(s)
- Christopher R Hall
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Jamie Conyard
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Ismael A Heisler
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Garth Jones
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | - James Frost
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Wesley R Browne
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen , Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Ben L Feringa
- Synthetic Organic Chemistry, Stratingh Institute for Chemistry, University of Groningen , Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Stephen R Meech
- School of Chemistry, University of East Anglia , Norwich Research Park, Norwich NR4 7TJ, U.K
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45
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Conyard J, Stacko P, Chen J, McDonagh S, Hall CR, Laptenok SP, Browne WR, Feringa BL, Meech SR. Ultrafast Excited State Dynamics in Molecular Motors: Coupling of Motor Length to Medium Viscosity. J Phys Chem A 2017; 121:2138-2150. [DOI: 10.1021/acs.jpca.7b00087] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Jamie Conyard
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Peter Stacko
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Jiawen Chen
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Sophie McDonagh
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Christopher R. Hall
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Sergey P. Laptenok
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
| | - Wesley R. Browne
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Ben L. Feringa
- Stratingh
Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Stephen R. Meech
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, U.K
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46
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Tay J, Parkes MA, Addison K, Chan Y, Zhang L, Hailes HC, Bulman Page PC, Meech SR, Blancafort L, Fielding HH. The Effect of Conjugation on the Competition between Internal Conversion and Electron Detachment: A Comparison between Green Fluorescent and Red Kaede Protein Chromophores. J Phys Chem Lett 2017; 8:765-771. [PMID: 28124921 DOI: 10.1021/acs.jpclett.7b00174] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Kaede, an analogue of green fluorescent protein (GFP), is a green-to-red photoconvertible fluorescent protein used as an in vivo "optical highlighter" in bioimaging. The fluorescence quantum yield of the red Kaede protein is lower than that of GFP, suggesting that increasing the conjugation modifies the electronic relaxation pathway. Using a combination of anion photoelectron spectroscopy and electronic structure calculations, we find that the isolated red Kaede protein chromophore in the gas phase is deprotonated at the imidazole ring, unlike the GFP chromophore that is deprotonated at the phenol ring. We find evidence of an efficient electronic relaxation pathway from higher-lying electronically excited states to the S1 state of the red Kaede chromophore that is not accessible in the GFP chromophore. Rapid autodetachment from high-lying vibrational states of S1 is found to compete efficiently with internal conversion to the ground electronic state.
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Affiliation(s)
- Jamie Tay
- Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K
| | - Michael A Parkes
- Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K
| | - Kiri Addison
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K
| | - Yohan Chan
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K
| | - Lijuan Zhang
- Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K
| | - Helen C Hailes
- Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K
| | | | - Stephen R Meech
- School of Chemistry, University of East Anglia , Norwich NR4 7TJ, U.K
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Facultat de Ciències, Universitat de Girona , Campus de Montilivi, C/M. A. Campmany 69, 17003 Girona, Spain
| | - Helen H Fielding
- Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, U.K
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Gil AA, Laptenok SP, French JB, Iuliano JN, Lukacs A, Hall CR, Sazanovich IV, Greetham GM, Bacher A, Illarionov B, Fischer M, Tonge PJ, Meech SR. Femtosecond to Millisecond Dynamics of Light Induced Allostery in the Avena sativa LOV Domain. J Phys Chem B 2017; 121:1010-1019. [PMID: 28068090 DOI: 10.1021/acs.jpcb.7b00088] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The rational engineering of photosensor proteins underpins the field of optogenetics, in which light is used for spatiotemporal control of cell signaling. Optogenetic elements function by converting electronic excitation of an embedded chromophore into structural changes on the microseconds to seconds time scale, which then modulate the activity of output domains responsible for biological signaling. Using time-resolved vibrational spectroscopy coupled with isotope labeling, we have mapped the structural evolution of the LOV2 domain of the flavin binding phototropin Avena sativa (AsLOV2) over 10 decades of time, reporting structural dynamics between 100 fs and 1 ms after optical excitation. The transient vibrational spectra contain contributions from both the flavin chromophore and the surrounding protein matrix. These contributions are resolved and assigned through the study of four different isotopically labeled samples. High signal-to-noise data permit the detailed analysis of kinetics associated with the light activated structural evolution. A pathway for the photocycle consistent with the data is proposed. The earliest events occur in the flavin binding pocket, where a subpicosecond perturbation of the protein matrix occurs. In this perturbed environment, the previously characterized reaction between triplet state isoalloxazine and an adjacent cysteine leads to formation of the adduct state; this step is shown to exhibit dispersive kinetics. This reaction promotes coupling of the optical excitation to successive time-dependent structural changes, initially in the β-sheet and then α-helix regions of the AsLOV2 domain, which ultimately gives rise to Jα-helix unfolding, yielding the signaling state. This model is tested through point mutagenesis, elucidating in particular the key mediating role played by Q513.
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Affiliation(s)
- Agnieszka A Gil
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - Sergey P Laptenok
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, U.K
| | - Jarrod B French
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - James N Iuliano
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - Andras Lukacs
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, U.K.,Department of Biophysics, Medical School, University of Pecs , Szigeti ut 12, 7624 Pecs, Hungary
| | | | - Igor V Sazanovich
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory , Didcot, Oxon OX11 0QX, U.K
| | - Gregory M Greetham
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory , Didcot, Oxon OX11 0QX, U.K
| | - Adelbert Bacher
- Department Chemie, Technische Universität München , D-85747 Garching, Germany
| | - Boris Illarionov
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg , Grindelallee 117, D-20146 Hamburg, Germany
| | - Markus Fischer
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg , Grindelallee 117, D-20146 Hamburg, Germany
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - Stephen R Meech
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, U.K
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de A Camargo FV, Grimmelsmann L, Anderson HL, Meech SR, Heisler IA. Resolving Vibrational from Electronic Coherences in Two-Dimensional Electronic Spectroscopy: The Role of the Laser Spectrum. Phys Rev Lett 2017; 118:033001. [PMID: 28157354 DOI: 10.1103/physrevlett.118.033001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Indexed: 05/11/2023]
Abstract
The observation of coherent quantum effects in photosynthetic light-harvesting complexes prompted the question whether quantum coherence could be exploited to improve the efficiency in new energy materials. The detailed characterization of coherent effects relies on sensitive methods such as two-dimensional electronic spectroscopy (2D-ES). However, the interpretation of the results produced by 2D-ES is challenging due to the many possible couplings present in complex molecular structures. In this work, we demonstrate how the laser spectral profile can induce electronic coherencelike signals in monomeric chromophores, potentially leading to data misinterpretation. We argue that the laser spectrum acts as a filter for certain coherence pathways and thus propose a general method to differentiate vibrational from electronic coherences.
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Affiliation(s)
- Franco V de A Camargo
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
- CAPES Foundation, Ministry of Education of Brazil, Brasilia DF 70040-202, Brazil
| | - Lena Grimmelsmann
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
- Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Harry L Anderson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Stephen R Meech
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Ismael A Heisler
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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Camargo FVA, Hall CR, Anderson HL, Meech SR, Heisler IA. Time resolved structural dynamics of butadiyne-linked porphyrin dimers. Struct Dyn 2016; 3:023608. [PMID: 26798839 PMCID: PMC4714993 DOI: 10.1063/1.4940222] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 01/06/2016] [Indexed: 06/05/2023]
Abstract
In this work, the timescales and mechanisms associated with the structural dynamics of butadiyne-linked porphyrin dimers are investigated through time resolved narrowband pump/broadband probe transient absorption spectroscopy. Our results confirm previous findings that the broadening is partly due to a distribution of structures with different (dihedral) angular conformations. Comparison of measurements with excitations on the red and blue sides of the Q-band unravel the ground and excited state conformational re-equilibration timescales. Further comparison to a planarized dimer, through the addition of a ligand, provides conclusive evidence for the twisting motion performed by the porphyrin dimer in solution.
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Affiliation(s)
| | - Christopher R Hall
- School of Chemistry, Norwich Research Park, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - Harry L Anderson
- Department of Chemistry, University of Oxford , Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom
| | - Stephen R Meech
- School of Chemistry, Norwich Research Park, University of East Anglia , Norwich NR4 7TJ, United Kingdom
| | - Ismael A Heisler
- School of Chemistry, Norwich Research Park, University of East Anglia , Norwich NR4 7TJ, United Kingdom
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