1
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Kang XW, Wang K, Zhang X, Zhong D, Ding B. Elementary Reactions in the Functional Triads of the Blue-Light Photoreceptor BLUF Domain. J Phys Chem B 2024; 128:2065-2075. [PMID: 38391132 DOI: 10.1021/acs.jpcb.3c07988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
The blue light using the flavin (BLUF) domain is one of the smallest photoreceptors in nature, which consists of a unique bidirectional electron-coupled proton relay process in its photoactivation reaction cycle. This perspective summarizes our recent efforts in dissecting the photocycle into three elementary processes, including proton-coupled electron transfer (PCET), proton rocking, and proton relay. Using ultrafast spectroscopy, we have determined the temporal sequence, rates, kinetic isotope effects (KIEs), and concertedness of these elementary steps. Our findings provide important implications for illuminating the photoactivation mechanism of the BLUF domain and suggest an engineering platform to characterize intricate reactions involving proton motions that are ubiquitous in nonphotosensitive protein machines.
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Affiliation(s)
- Xiu-Wen Kang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Kailin Wang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaofan Zhang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dongping Zhong
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Programs of Chemical Physics, and Programs of Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Bei Ding
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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2
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Le DPN, Hastings G, Gozem S. How Aqueous Solvation Impacts the Frequencies and Intensities of Infrared Absorption Bands in Flavin: The Quest for a Suitable Solvent Model. Molecules 2024; 29:520. [PMID: 38276598 PMCID: PMC10818357 DOI: 10.3390/molecules29020520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/27/2024] Open
Abstract
FTIR spectroscopy accompanied by quantum chemical simulations can reveal important information about molecular structure and intermolecular interactions in the condensed phase. Simulations typically account for the solvent either through cluster quantum mechanical (QM) models, polarizable continuum models (PCM), or hybrid quantum mechanical/molecular mechanical (QM/MM) models. Recently, we studied the effect of aqueous solvent interactions on the vibrational frequencies of lumiflavin, a minimal flavin model, using cluster QM and PCM models. Those models successfully reproduced the relative frequencies of four prominent stretching modes of flavin's isoalloxazine ring in the diagnostic 1450-1750 cm-1 range but poorly reproduced the relative band intensities. Here, we extend our studies on this system and account for solvation through a series of increasingly sophisticated models. Only by combining elements of QM clusters, QM/MM, and PCM approaches do we obtain an improved agreement with the experiment. The study sheds light more generally on factors that can impact the computed frequencies and intensities of IR bands in solution.
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Affiliation(s)
- D. P. Ngan Le
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA; (D.P.N.L.); (G.H.)
| | - Gary Hastings
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA; (D.P.N.L.); (G.H.)
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA; (D.P.N.L.); (G.H.)
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3
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Nakasone Y, Murakami H, Tokonami S, Oda T, Terazima M. Time-resolved study on signaling pathway of photoactivated adenylate cyclase and its nonlinear optical response. J Biol Chem 2023; 299:105285. [PMID: 37742920 PMCID: PMC10634658 DOI: 10.1016/j.jbc.2023.105285] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/06/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023] Open
Abstract
Photoactivated adenylate cyclases (PACs) are multidomain BLUF proteins that regulate the cellular levels of cAMP in a light-dependent manner. The signaling route and dynamics of PAC from Oscillatoria acuminata (OaPAC), which consists of a light sensor BLUF domain, an adenylate cyclase domain, and a connector helix (α3-helix), were studied by detecting conformational changes in the protein moiety. Although circular dichroism and small-angle X-ray scattering measurements did not show significant changes upon light illumination, the transient grating method successfully detected light-induced changes in the diffusion coefficient (diffusion-sensitive conformational change (DSCC)) of full-length OaPAC and the BLUF domain with the α3-helix. DSCC of full-length OaPAC was observed only when both protomers in a dimer were photoconverted. This light intensity dependence suggests that OaPAC is a cyclase with a nonlinear light intensity response. The enzymatic activity indeed nonlinearly depends on light intensity, that is, OaPAC is activated under strong light conditions. It was also found that both DSCC and enzymatic activity were suppressed by a mutation in the W90 residue, indicating the importance of the highly conserved Trp in many BLUF domains for the function. Based on these findings, a reaction scheme was proposed together with the reaction dynamics.
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Affiliation(s)
- Yusuke Nakasone
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Hiroto Murakami
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Shunrou Tokonami
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Takashi Oda
- Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Tokyo, Japan
| | - Masahide Terazima
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan.
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4
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Ramírez Martínez C, Gómez-Pérez LS, Ordaz A, Torres-Huerta AL, Antonio-Perez A. Current Trends of Bacterial and Fungal Optoproteins for Novel Optical Applications. Int J Mol Sci 2023; 24:14741. [PMID: 37834188 PMCID: PMC10572898 DOI: 10.3390/ijms241914741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 10/15/2023] Open
Abstract
Photoproteins, luminescent proteins or optoproteins are a kind of light-response protein responsible for the conversion of light into biochemical energy that is used by some bacteria or fungi to regulate specific biological processes. Within these specific proteins, there are groups such as the photoreceptors that respond to a given light wavelength and generate reactions susceptible to being used for the development of high-novel applications, such as the optocontrol of metabolic pathways. Photoswitchable proteins play important roles during the development of new materials due to their capacity to change their conformational structure by providing/eliminating a specific light stimulus. Additionally, there are bioluminescent proteins that produce light during a heatless chemical reaction and are useful to be employed as biomarkers in several fields such as imaging, cell biology, disease tracking and pollutant detection. The classification of these optoproteins from bacteria and fungi as photoreceptors or photoresponse elements according to the excitation-emission spectrum (UV-Vis-IR), as well as their potential use in novel applications, is addressed in this article by providing a structured scheme for this broad area of knowledge.
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Affiliation(s)
| | | | | | | | - Aurora Antonio-Perez
- Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Campus Estado de México, Av. Lago de Guadalupe KM 3.5, Margarita Maza de Juárez, Ciudad López Mateos, Atizapán de Zaragoza 52926, Estado de México, Mexico; (C.R.M.); (L.S.G.-P.); (A.O.); (A.L.T.-H.)
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5
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Sugo Y, Ishikita H. Mechanism of Asparagine-Mediated Proton Transfer in Photosynthetic Reaction Centers. Biochemistry 2023; 62:1544-1552. [PMID: 37083399 PMCID: PMC10194076 DOI: 10.1021/acs.biochem.3c00013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/29/2023] [Indexed: 04/22/2023]
Abstract
In photosynthetic reaction centers from purple bacteria (PbRCs), light-induced charge separation leads to the reduction of the terminal electron acceptor quinone, QB. The reduction of QB to QB•- is followed by protonation via Asp-L213 and Ser-L223 in PbRC from Rhodobacter sphaeroides. However, Asp-L213 is replaced with nontitratable Asn-L222 and Asn-L213 in PbRCs from Thermochromatium tepidum and Blastochloris viridis, respectively. Here, we investigated the energetics of proton transfer along the asparagine-involved H-bond network using a quantum mechanical/molecular mechanical approach. The potential energy profile for the H-bond between H3O+ and the carbonyl O site of Asn-L222 shows that the proton is predominantly localized at the Asn-L222 moiety in the T. tepidum PbRC protein environment, easily forming the enol species. The release of the proton from the amide -NH2 site toward Ser-L232 via tautomerization suffers from the energy barrier. Upon reorientation of Asn-L222, the enol -OH site forms a short low-barrier H-bond with Ser-L232, facilitating protonation of QB•- in a Grotthuss-like mechanism. This is a basis of how asparagine or glutamine side chains function as acceptors/donors in proton transfer pathways.
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Affiliation(s)
- Yu Sugo
- Department
of Applied Chemistry, The University of
Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
| | - Hiroshi Ishikita
- Department
of Applied Chemistry, The University of
Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
- Research
Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
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6
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Hontani Y, Mehlhorn J, Domratcheva T, Beck S, Kloz M, Hegemann P, Mathes T, Kennis JTM. Spectroscopic and Computational Observation of Glutamine Tautomerization in the Blue Light Sensing Using Flavin Domain Photoreaction. J Am Chem Soc 2023; 145:1040-1052. [PMID: 36607126 PMCID: PMC9853863 DOI: 10.1021/jacs.2c10621] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Blue light sensing using flavin (BLUF) domains constitute a family of flavin-binding photoreceptors of bacteria and eukaryotic algae. BLUF photoactivation proceeds via a light-driven hydrogen-bond switch among flavin adenine dinucleotide (FAD) and glutamine and tyrosine side chains, whereby FAD undergoes electron and proton transfer with tyrosine and is subsequently re-oxidized by a hydrogen back-shuttle in picoseconds, constituting an important model system to understand proton-coupled electron transfer in biology. The specific structure of the hydrogen-bond patterns and the prevalence of glutamine tautomeric states in dark-adapted (DA) and light-activated (LA) states have remained controversial. Here, we present a combined femtosecond stimulated Raman spectroscopy (FSRS), computational chemistry, and site-selective isotope labeling Fourier-transform infrared spectroscopy (FTIR) study of the Slr1694 BLUF domain. FSRS showed distinct vibrational bands from the FADS1 singlet excited state. We observed small but significant shifts in the excited-state vibrational frequency patterns of the DA and LA states, indicating that these frequencies constitute a sensitive probe for the hydrogen-bond arrangement around FAD. Excited-state model calculations utilizing four different realizations of hydrogen bond patterns and glutamine tautomeric states were consistent with a BLUF reaction model that involved glutamine tautomerization to imidic acid, accompanied by a rotation of its side chain. A combined FTIR and double-isotope labeling study, with 13C labeling of FAD and 15N labeling of glutamine, identified the glutamine imidic acid C═N stretch vibration in the LA state and the Gln C═O in the DA state. Hence, our study provides support for glutamine tautomerization and side-chain rotation in the BLUF photoreaction.
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Affiliation(s)
- Yusaku Hontani
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands
| | - Jennifer Mehlhorn
- Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Tatiana Domratcheva
- Department
of Biomolecular Mechanisms, Max Planck Institute
for Medical Research, 69120 Heidelberg, Germany,Department
of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Sebastian Beck
- Department
of Chemistry, Humboldt-Universität
zu Berlin, Brook-Taylor-Str.
2, 12489 Berlin, Germany
| | - Miroslav Kloz
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,Institute
of Physics, ELI-Beamlines, Na Slovance 2, 182
21 Praha 8, Czech Republic
| | - Peter Hegemann
- Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Tilo Mathes
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - John T. M. Kennis
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,
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7
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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] [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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8
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The nature of proton-coupled electron transfer in a blue light using flavin domain. Proc Natl Acad Sci U S A 2022; 119:e2203996119. [PMID: 35737837 PMCID: PMC9245699 DOI: 10.1073/pnas.2203996119] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Proton-coupled electron transfer (PCET) is key to the activation of the blue light using flavin (BLUF) domain photoreceptors. Here, to elucidate the photocycle of the central FMN-Gln-Tyr motif in the BLUF domain of OaPAC, we eliminated the intrinsic interfering W90 in the mutant design. We integrated the stretched exponential function into the target analysis to account for the dynamic heterogeneity arising from the active-site solvation relaxation and the flexible H-bonding network as shown in the molecular dynamics simulation results, facilitating a simplified expression of the kinetics model. We find that, in both the functional wild-type (WT) and the nonfunctional Q48E and Q48A, forward PCET happens in the range of 105 ps to 344 ps, with a kinetic isotope effect (KIE) measured to be ∼1.8 to 2.4, suggesting that the nature of the forward PCET is concerted. Remarkably, only WT proceeds with an ultrafast reverse PCET process (31 ps, KIE = 4.0), characterized by an inverted kinetics of the intermediate FMNH˙. Our results reveal that the reverse PCET is driven by proton transfer via an intervening imidic Gln.
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9
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Nakasone Y, Terazima M. Time-resolved diffusion reveals photoreactions of BLUF proteins with similar functional domains. Photochem Photobiol Sci 2022; 21:493-507. [PMID: 35391638 DOI: 10.1007/s43630-022-00214-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/21/2022] [Indexed: 11/30/2022]
Abstract
BLUF (blue light sensor using flavin) proteins are the blue light receptors that consist of flavin-binding BLUF domains and functional domains. Upon blue light excitation, the hydrogen bond network around the flavin chromophore changes, and the absorption spectrum in the visible region shifts to red. Light signal received in the BLUF domain is intramolecularly or intermolecularly transmitted to the functional region. In this review, the reactions of three BLUF proteins with similar EAL functional groups within the protein (BlrP1, and YcgF), or with a separated target protein (PapB) are described using time-resolved diffusion technique. The diffusion coefficients (D) of the BLUF domains did not significantly change upon photoexcitation, whereas those of the full-length proteins BlrP1 and YcgF and the PapB-PapA system significantly decreased. The changes in D should be due to diffusion-sensitive conformational changes (DSCC) that alter the friction of diffusion. The time constants of the major D changes of BlrP1 and PapB-PapA were similar (~ 20 ms), although the magnitude of the friction change depended on the proteins. Similarities and differences among the reactions of these proteins were clarified from the viewpoint of DSCC.
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Affiliation(s)
- Yusuke Nakasone
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Masahide Terazima
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan.
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10
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Understanding flavin electronic structure and spectra. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1541] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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11
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Tokonami S, Onose M, Nakasone Y, Terazima M. Slow Conformational Changes of Blue Light Sensor BLUF Proteins in Milliseconds. J Am Chem Soc 2022; 144:4080-4090. [PMID: 35196858 DOI: 10.1021/jacs.1c13121] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Blue light sensor using flavin (BLUF) proteins consist of flavin-binding BLUF domains and functional domains. Upon blue light excitation, the hydrogen bond network around the flavin chromophore changes, and the absorption spectrum in the visible region exhibits a red shift. Ultimately, the light information received in the BLUF domain is transmitted to the functional region. It has been believed that this red shift is complete within nanoseconds. In this study, slow reaction kinetics were discovered in milliseconds (τ1- and τ2-phase) for all the BLUF proteins examined (AppA, OaPAC, BlrP1, YcgF, PapB, SyPixD, and TePixD). Despite extensive reports on BLUF, this is the first clear observation of the BLUF protein absorption change with the duration in the millisecond time region. From the measurements of some domain-deleted mutants of OaPAC and two chimeric mutants of PixD proteins, it was found that the slower dynamics (τ2-phase) are strongly affected by the size and nature of the C-terminal region adjacent to the BLUF domain. Hence, this millisecond reaction is a significant indicator of conformational changes in the C-terminal region, which is essential for the biological functions. On the other hand, the τ1-phase commonly exists in all BLUF proteins, including any mutants. The origin of the slow dynamics was studied using site-specific mutants. These results clearly show the importance of Trp in the BLUF domain. Based on this, a reaction scheme for the BLUF reaction is proposed.
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Affiliation(s)
- Shunrou Tokonami
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Morihiko Onose
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yusuke Nakasone
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Masahide Terazima
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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12
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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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13
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Kang X, Chen Z, Zhou Z, Zhou Y, Tang S, Zhang Y, Zhang T, Ding B, Zhong D. Direct Observation of Ultrafast Proton Rocking in the BLUF Domain. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202114423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Xiu‐Wen Kang
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Zijing Chen
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Zhongneng Zhou
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Yalin Zhou
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Siwei Tang
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Yifei Zhang
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Tianyi Zhang
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Bei Ding
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
| | - Dongping Zhong
- Center for Ultrafast Science and Technology School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China
- Department of Physics Department of Chemistry and Biochemistry and Programs of Biophysics Chemical Physics, and Biochemistry The Ohio State University Columbus OH 43210 USA
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14
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Ding B, Kang XW, Chen Z, Zhou Z, Zhou Y, Tang S, Zhang Y, Zhang T, Zhong D. Direct Observation of Ultrafast Proton Rocking in the BLUF Domain. Angew Chem Int Ed Engl 2021; 61:e202114423. [PMID: 34927328 DOI: 10.1002/anie.202114423] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Indexed: 11/10/2022]
Abstract
We present direct observation of ultrafast proton rocking in the central motif of a BLUF domain protein scaffold. The mutant design has taken considerations of modulating the proton-coupled electron transfer (PCET) driving forces by replacing Tyr in the original motif with Trp, as well as of removing the interference of a competing electron transfer pathway. Using femtosecond pump-probe spectroscopy and detailed kinetics analysis, we resolved an electron-transfer-coupled Grotthuss-type forward and reversed proton rocking along the FMN-Gln-Trp proton relay chain. The rates of forward and reversed proton transfer are determined to be very close, namely 51 ps vs 52 ps. The kinetic isotope effect (KIE) constants associated with the forward and reversed proton transfer are 3.9 and 5.3, respectively. The observation of ultrafast proton rocking is not only a crucial step towards revealing the nature of proton relay in BLUF domain, but also provides a new paradigm of proton transfer in proteins for theoretical investigations.
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Affiliation(s)
- Bei Ding
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, 800 Dongchuan Road, 200240, Shanghai, CHINA
| | - Xiu-Wen Kang
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Zijing Chen
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Zhongneng Zhou
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Yalin Zhou
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Siwei Tang
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Yifei Zhang
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Tianyi Zhang
- Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA
| | - Dongping Zhong
- The Ohio State University, Department of Chemical and Biomolecular Engineering, CHINA
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15
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Kabir MP, Orozco-Gonzalez Y, Hastings G, Gozem S. The effect of hydrogen-bonding on flavin's infrared absorption spectrum. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 262:120110. [PMID: 34224983 DOI: 10.1016/j.saa.2021.120110] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Cluster and continuum solvation computational models are employed to model the effect of hydrogen bonding interactions on the vibrational modes of lumiflavin. Calculated spectra were compared to experimental Fourier-transform infrared (FTIR) spectra in the diagnostic 1450-1800 cm-1 range, where intense νC=C, νC=N, [Formula: see text] , and [Formula: see text] stretching modes of flavin's isoalloxazine ring are found. Local mode analysis is used to describe the strength of hydrogen-bonding in cluster models. The computations indicate that νC=C and νC=N mode frequencies are relatively insensitive to intermolecular interactions while the [Formula: see text] and [Formula: see text] modes are sensitive to direct (and also indirect for [Formula: see text] ) hydrogen-bonding interactions. Although flavin is neutral, basis sets without the diffuse functions provide incorrect relative frequencies and intensities. The 6-31+G* basis set is found to be adequate for this system, and there is limited benefit to considering larger basis sets. Calculated vibrational mode frequencies agree with experimentally determined frequencies in solution when cluster models with multiple water molecules are used. Accurate simulation of relative FTIR band intensities, on the other hand, requires a continuum (or possibly quantum mechanical/molecular mechanical) model that accounts for long-range electrostatic effects. Finally, an experimental peak at ca. 1624 cm-1 that is typically assigned to the [Formula: see text] vibrational stretching mode has a complicated shape that suggests multiple underlying contributions. Our calculations show that this band has contributions from both the C6-C7 and C2 = O stretching vibrations.
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Affiliation(s)
- Mohammad Pabel Kabir
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, United States
| | | | - Gary Hastings
- Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302, United States; Center for Nano-Optics, Georgia State University, Atlanta, GA 30302, United States.
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, GA 30302, United States.
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16
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Fujisawa T, Masuda S, Takeuchi S, Tahara T. Femtosecond Time-Resolved Absorption Study of Signaling State of a BLUF Protein PixD from the Cyanobacterium Synechocystis: Hydrogen-Bond Rearrangement Completes during Forward Proton-Coupled Electron Transfer. J Phys Chem B 2021; 125:12154-12165. [PMID: 34726926 DOI: 10.1021/acs.jpcb.1c05957] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Femtosecond time-resolved absorption measurements were carried out for the dark and signaling states of a BLUF (Blue Light Using FAD) protein, PixD, from the cyanobacterium Synechocystis. When the dark state was excited, FAD semiquinone radical (FADH•) was produced from the S1 state, and FADH• led to the signaling state. On the other hand, photoexcitation of the signaling state generated FADH• and FAD anion radical (FAD•-), and they decayed back to the original signaling state. In both cases, FADH• was formed and decayed with a proton-coupled electron transfer (PCET) via the hydrogen-bond network that involves FAD, Gln50, and Tyr8, and hence the kinetics of FADH• directly reflects the hydrogen-bond structure in the FAD-binding sites. It was found that the formation rate of FADH• was significantly different between the dark and signaling states, whereas the decay rate was the same. This indicates that the hydrogen-bond network of FAD-Gln50-Tyr8 in the dark and signaling states is initially different but it becomes indistinguishable after FADH• is formed, implying that the FAD-Gln50-Tyr8 hydrogen-bond network is rearranged during the PCET to generate FADH•. The present results best agree with the model in which the Gln tautomerizes without rotation in the signaling-state formation.
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Affiliation(s)
- Tomotsumi Fujisawa
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Shinji Masuda
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Satoshi Takeuchi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
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17
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Hashem S, Macaluso V, Nottoli M, Lipparini F, Cupellini L, Mennucci B. From crystallographic data to the solution structure of photoreceptors: the case of the AppA BLUF domain. Chem Sci 2021; 12:13331-13342. [PMID: 34777752 PMCID: PMC8528011 DOI: 10.1039/d1sc03000k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 09/01/2021] [Indexed: 12/28/2022] Open
Abstract
Photoreceptor proteins bind a chromophore, which, upon light absorption, modifies its geometry or its interactions with the protein, finally inducing the structural change needed to switch the protein from an inactive to an active or signaling state. In the Blue Light-Using Flavin (BLUF) family of photoreceptors, the chromophore is a flavin and the changes have been connected with a rearrangement of the hydrogen bond network around it on the basis of spectroscopic changes measured for the dark-to-light conversion. However, the exact conformational change triggered by the photoexcitation is still elusive mainly because a clear consensus on the identity not only of the light activated state but also of the dark one has not been achieved. Here, we present an integrated investigation that combines microsecond MD simulations starting from the two conflicting crystal structures available for the AppA BLUF domain with calculations of NMR, IR and UV-Vis spectra using a polarizable QM/MM approach. Thanks to such a combined analysis of the three different spectroscopic responses, a robust characterization of the structure of the dark state in solution is given together with the uncovering of important flaws of the most popular molecular mechanisms present in the literature for the dark-to-light activation.
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Affiliation(s)
- Shaima Hashem
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Veronica Macaluso
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Michele Nottoli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Filippo Lipparini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Lorenzo Cupellini
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
| | - Benedetta Mennucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa Via G. Moruzzi 13 56124 Pisa Italy
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18
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Iwasaki T, Miyajima-Nakano Y, Fukazawa R, Lin MT, Matsushita SI, Hagiuda E, Taguchi AT, Dikanov SA, Oishi Y, Gennis RB. Escherichia coli amino acid auxotrophic expression host strains for investigating protein structure-function relationships. J Biochem 2021; 169:387-394. [PMID: 33289521 DOI: 10.1093/jb/mvaa140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/16/2020] [Indexed: 11/13/2022] Open
Abstract
A set of C43(DE3) and BL21(DE3) Escherichia coli host strains that are auxotrophic for various amino acids is briefly reviewed. These strains require the addition of a defined set of one or more amino acids in the growth medium, and have been specifically designed for overproduction of membrane or water-soluble proteins selectively labelled with stable isotopes, such as 2H, 13C and 15N. The strains described here are available for use and have been deposited into public strain banks. Although they cannot fully eliminate the possibility of isotope dilution and mixing, metabolic scrambling of the different amino acid types can be minimized through a careful consideration of the bacterial metabolic pathways. The use of a suitable auxotrophic expression host strain with an appropriately isotopically labelled growth medium ensures high levels of isotope labelling efficiency as well as selectivity for providing deeper insight into protein structure-function relationships.
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Affiliation(s)
- Toshio Iwasaki
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Yoshiharu Miyajima-Nakano
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Risako Fukazawa
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | | | - Shin-Ichi Matsushita
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Emi Hagiuda
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Alexander T Taguchi
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
| | - Sergei A Dikanov
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yumiko Oishi
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Tokyo 113-8602, Japan
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19
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Tomida S, Kitagawa S, Kandori H, Furutani Y. Inverse Hydrogen-Bonding Change Between the Protonated Retinal Schiff Base and Water Molecules upon Photoisomerization in Heliorhodopsin 48C12. J Phys Chem B 2021; 125:8331-8341. [PMID: 34292728 DOI: 10.1021/acs.jpcb.1c01907] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Heliorhodopsin (HeR) is a new class of the rhodopsin family discovered in 2018 through functional metagenomic analysis (named 48C12). Similar to typical microbial rhodopsins, HeR possesses seven transmembrane (TM) α-helices and an all-trans-retinal covalently bonded to the lysine residue on TM7 via a protonated Schiff base. Remarkably, the HeR membrane topology is inverted compared with that of typical microbial rhodopsins. The X-ray crystal structure of HeR 48C12 was elucidated after the first report on a HeR variant from Thermoplasmatales archaeon SG8-52-1, which revealed the water-mediated hydrogen-bonding network connected to the Schiff base region in the cytoplasmic side. Herein, low-temperature light-induced FTIR spectroscopic analyses of HeR 48C12 and 15N isotopically labeled proteins were used to elucidate the structural changes during retinal photoisomerization. N-D stretching vibrations of the protonated retinal Schiff base (PRSB) at 2286 and 2302 cm-1 in the dark state, and 2239 and 2252 cm-1 in the K intermediate were observed. The frequency changes indicated that the hydrogen bond of PRSB strengthens upon photoisomerization in HeR. Moreover, O-D stretching vibration frequencies of the internal water molecules indicate that the hydrogen-bonding strength decreases concomitantly. Therefore, the PRSB hydrogen bond responds to photoisomerization in an opposite way to the hydrogen-bonding network involving water molecules. No frequency changes of the indole N-H or N-D stretching vibrations of tryptophan residues were observed upon photoisomerization, suggesting that all tryptophan residues in the HeR 48C12 maintained the hydrogen-bonding strengths in the K intermediate. These results provide insights into the molecular mechanism of the energy storage and propagation upon retinal photoisomerization in HeR.
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Affiliation(s)
- Sahoko Tomida
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Shinya Kitagawa
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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20
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Andrikopoulos PC, Chaudhari AS, Liu Y, Konold PE, Kennis JTM, Schneider B, Fuertes G. QM calculations predict the energetics and infrared spectra of transient glutamine isomers in LOV photoreceptors. Phys Chem Chem Phys 2021; 23:13934-13950. [PMID: 34142688 PMCID: PMC8246142 DOI: 10.1039/d1cp00447f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/04/2021] [Indexed: 11/21/2022]
Abstract
Photosensory receptors containing the flavin-binding light-oxygen-voltage (LOV) domain are modular proteins that fulfil a variety of biological functions ranging from gene expression to phototropism. The LOV photocycle is initiated by blue-light and involves a cascade of intermediate species, including an electronically excited triplet state, that leads to covalent bond formation between the flavin mononucleotide (FMN) chromophore and a nearby cysteine residue. Subsequent conformational changes in the polypeptide chain arise due to the remodelling of the hydrogen bond network in the cofactor binding pocket, whereby a conserved glutamine residue plays a key role in coupling FMN photochemistry with LOV photobiology. Although the dark-to-light transition of LOV photosensors has been previously addressed by spectroscopy and computational approaches, the mechanistic basis of the underlying reactions is still not well understood. Here we present a detailed computational study of three distinct LOV domains: EL222 from Erythrobacter litoralis, AsLOV2 from the second LOV domain of Avena sativa phototropin 1, and RsLOV from Rhodobacter sphaeroides LOV protein. Extended protein-chromophore models containing all known crucial residues involved in the initial steps (femtosecond-to-microsecond) of the photocycle were employed. Energies and rotational barriers were calculated for possible rotamers and tautomers of the critical glutamine side chain, which allowed us to postulate the most energetically favoured glutamine orientation for each LOV domain along the assumed reaction path. In turn, for each evolving species, infrared difference spectra were constructed and compared to experimental EL222 and AsLOV2 transient infrared spectra, the former from original work presented here and the latter from the literature. The good agreement between theory and experiment permitted the assignment of the majority of observed bands, notably the ∼1635 cm-1 transient of the adduct state to the carbonyl of the glutamine side chain after rotation. Moreover, both the energetic and spectroscopic approaches converge in suggesting a facile glutamine flip at the adduct intermediate for EL222 and more so for AsLOV2, while for RsLOV the glutamine keeps its initial configuration. Additionally, the computed infrared shifts of the glutamine and interacting residues could guide experimental research addressing early events of signal transduction in LOV proteins.
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Affiliation(s)
- Prokopis C Andrikopoulos
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Aditya S Chaudhari
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Yingliang Liu
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Patrick E Konold
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - John T M Kennis
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - Bohdan Schneider
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Gustavo Fuertes
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
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21
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Pinto SMV, Tasinato N, Barone V, Zanetti-Polzi L, Daidone I. A computational insight into the relationship between side chain IR line shapes and local environment in fibril-like structures. J Chem Phys 2021; 154:084105. [PMID: 33639764 DOI: 10.1063/5.0038913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Infrared spectroscopy is a widely used technique to characterize protein structures and protein mediated processes. While the amide I band provides information on proteins' secondary structure, amino acid side chains are used as infrared probes for the investigation of protein reactions and local properties. In this paper, we use a hybrid quantum mechanical/classical molecular dynamical approach based on the perturbed matrix method to compute the infrared band due to the C=O stretching mode of amide-containing side chains. We calculate, at first, the infrared band of zwitterionic glutamine in water and obtain results in very good agreement with the experimental data. Then, we compute the signal arising from glutamine side chains in a microcrystal of the yeast prion Sup35-derived peptide, GNNQQNY, with a fibrillar structure. The infrared bands obtained by selective isotopic labeling of the two glutamine residues, Q4 and Q5, of each peptide were experimentally used to investigate the local hydration in the fibrillar microcrystal. The experimental spectra of the two glutamine residues, which experience different hydration environments, feature different spectral signals that are well reproduced by the corresponding calculated spectra. In addition, the analysis of the simulated spectra clarifies the molecular origin of the experimentally observed spectroscopic differences that arise from the different local electric field experienced by the two glutamine residues, which is, in turn, determined by a different hydrogen bonding pattern.
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Affiliation(s)
- Sandra M V Pinto
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Nicola Tasinato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
| | | | - Isabella Daidone
- Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, I-67100 L'Aquila, Italy
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22
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Unno M, Hirose Y, Mishima M, Kikukawa T, Fujisawa T, Iwata T, Tamogami J. Spectroscopic approach for exploring structure and function of photoreceptor proteins. Biophys Physicobiol 2021; 18:127-130. [PMID: 34178563 PMCID: PMC8214923 DOI: 10.2142/biophysico.bppb-v18.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 05/11/2021] [Indexed: 12/01/2022] Open
Affiliation(s)
- Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Yuu Hirose
- Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Masaki Mishima
- Department of Molecular Biophysics, Tokyo University of Pharmacy and Life Sciences, School of Pharmacy, Hachioji, Tokyo 192-0392, Japan
| | - Takashi Kikukawa
- Faculty of Advanced Life Science and Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan
| | - Tatsuya Iwata
- Department of Pharmaceutical Sciences, Toho University, Funabashi, Chiba 274-8510, Japan
| | - Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
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23
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Levina EO, Khrenova MG, Tsirelson VG. The explicit role of electron exchange in the hydrogen bonded molecular complexes. J Comput Chem 2021; 42:870-882. [PMID: 33675552 DOI: 10.1002/jcc.26507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 01/22/2023]
Abstract
We applied a set of advanced bonding descriptors to establish the hidden electron density features and binding energy characteristics of intermolecular DH∙∙∙A hydrogen bonds (OH∙∙∙O, NH∙∙∙O and SH∙∙∙O) in 150 isolated and solvated molecular complexes. The exchange-correlation and Pauli potentials as well as corresponding local one-electron forces allowed us to explicitly ascertain how electron exchange defines the bonding picture in the proximity of the H-bond critical point. The electron density features of DH∙∙∙A interaction are governed by alterations in the electron localization in the H-bond region displaying itself in the exchange hole. At that, they do not depend on the variations in the exchange hole mobility. The electrostatic interaction mainly defines the energy of H-bonds of different types, whereas the strengthening/weakening of H-bonds in complexes with varying substituents depends on the barrier height of the exchange potential near the bond critical point. Energy variations between H-bonds in isolated and solvated systems are also caused the electron exchange peculiarities as follows from the corresponding potential and the interacting quantum atom analyses complemented by electron delocalization index calculations. Our approach is based on the bonding descriptors associated with the characteristics of the observable electron density and can be recommended for in-depth studies of non-covalent bonding.
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Affiliation(s)
- Elena O Levina
- Federal Research Centre "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Maria G Khrenova
- Federal Research Centre "Fundamentals of Biotechnology" of the Russian Academy of Sciences, Moscow, Russia.,Moscow Institute of Physics and Technology, Dolgoprudny, Russia.,Lomonosov Moscow State University, Moscow, Russia
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24
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Hou C, Xu C, Yi B, Huang X, Cao C, Lee Y, Chen S, Yao X. Mechano-Induced Assembly of a Nanocomposite for "Press-N-Go" Coatings with Highly Efficient Surface Disinfection. ACS APPLIED MATERIALS & INTERFACES 2021; 13:19332-19341. [PMID: 33871976 DOI: 10.1021/acsami.1c03156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Using antimicrobial coatings to control the spread of pathogenic microbes is appreciated in public and healthcare settings, but the performance of most antimicrobial coatings could not fulfill the increasing requirements, particularly the ease of preparation, high durability, rapid response, and high killing efficiency. Herein, we develop a new type of mechano-induced assembly of nanocomposite coating by simple "Press-N-Go" procedures on various substrates such as glassware, gloves, and fabrics, in which the coating shows strong adhesion, high shear stability, and high stiffness, making it durable in daily use to withstand common mechanical deformation and scratches. The coating also shows remarkable disinfection effectiveness over 99.9% to clinically significant multiple drug-resistant bacterial pathogens upon only 6 s near-infrared irradiation, which can be further improved to over 99.9999% upon another 6 s treatment. We envision that the coating can provide convenience and values to control pathogen spread for easily contaminated substrates in high-risk areas.
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Affiliation(s)
- Changshun Hou
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Chen Xu
- Department of Infectious Diseases and Public Health, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Bo Yi
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Xin Huang
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Chunyan Cao
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Youngjin Lee
- Department of Neuroscience, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Sheng Chen
- Department of Infectious Diseases and Public Health, City University of Hong Kong, Kowloon 999077, P. R. China
| | - Xi Yao
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon 999077, P. R. China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518075, P. R. China
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25
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Khrenova MG, Kulakova AM, Nemukhin AV. Light-Induced Change of Arginine Conformation Modulates the Rate of Adenosine Triphosphate to Cyclic Adenosine Monophosphate Conversion in the Optogenetic System Containing Photoactivated Adenylyl Cyclase. J Chem Inf Model 2021; 61:1215-1225. [PMID: 33677973 DOI: 10.1021/acs.jcim.0c01308] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We report the first computational characterization of an optogenetic system composed of two photosensing BLUF (blue light sensor using flavin adenine dinucleotide) domains and two catalytic adenylyl cyclase (AC) domains. Conversion of adenosine triphosphate (ATP) to the reaction products, cyclic adenosine monophosphate (cAMP) and pyrophosphate (PPi), catalyzed by ACs initiated by excitation in photosensing domains has emerged in the focus of modern optogenetic applications because of the request in photoregulated enzymes that modulate cellular concentrations of signaling messengers. The photoactivated AC from the soil bacterium Beggiatoa sp. (bPAC) is an important model showing a considerable increase in the ATP to cAMP conversion rate in the catalytic domain after the illumination of the BLUF domain. The 1 μs classical molecular dynamics simulations reveal that the activation of the BLUF domain leading to tautomerization of Gln49 in the chromophore-binding pocket results in switching of the position of the side chain of Arg278 in the active site of AC. Allosteric signal transmission pathways between Gln49 from BLUF and Arg278 from AC were revealed by the dynamical network analysis. The Gibbs energy profiles of the ATP → cAMP + PPi reaction computed using QM(DFT(ωB97X-D3/6-31G**))/MM(CHARMM) molecular dynamics simulations for both Arg278 conformations in AC clarify the reaction mechanism. In the light-activated system, the corresponding arginine conformation stabilizes the pentacoordinated phosphorus of the α-phosphate group in the transition state, thus lowering the activation energy. Simulations of the bPAC system with the Tyr7Phe replacement in the BLUF demonstrate occurrence of both arginine conformations in an equal ratio, explaining the experimentally observed intermediate catalytic activity of the bPAC-Y7F variant as compared with the dark and light states of the wild-type bPAC.
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Affiliation(s)
- Maria G Khrenova
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russian Federation.,Bach Institute of Biochemistry, Federal Research Centre "Fundamentals of Biotechnology", Russian Academy of Sciences, Moscow 119071 Russian Federation
| | - Anna M Kulakova
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russian Federation
| | - Alexander V Nemukhin
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russian Federation.,Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow 119334, Russian Federation
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Photoreaction Mechanisms of Flavoprotein Photoreceptors and Their Applications. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:189-206. [PMID: 33398814 DOI: 10.1007/978-981-15-8763-4_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
Three classes of flavoprotein photoreceptors, cryptochromes (CRYs), light-oxygen-voltage (LOV)-domain proteins, and blue light using FAD (BLUF)-domain proteins, have been identified that control various physiological processes in multiple organisms. Accordingly, signaling activities of photoreceptors have been intensively studied and the related mechanisms have been exploited in numerous optogenetic tools. Herein, we summarize the current understanding of photoactivation mechanisms of the flavoprotein photoreceptors and review their applications.
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27
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Hashem S, Cupellini L, Lipparini F, Mennucci B. A polarisable QM/MM description of NMR chemical shifts of a photoreceptor protein. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1771449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Shaima Hashem
- Department of Chemistry, University of Pisa, Pisa, Italy
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28
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Kandori H. Structure/Function Study of Photoreceptive Proteins by FTIR Spectroscopy. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20200109] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Hideki Kandori
- Department of Life Science and Applied Chemistry & OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
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29
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Deazaflavin reductive photocatalysis involves excited semiquinone radicals. Nat Commun 2020; 11:3174. [PMID: 32576821 PMCID: PMC7311442 DOI: 10.1038/s41467-020-16909-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/02/2020] [Indexed: 11/30/2022] Open
Abstract
Flavin-mediated photocatalytic oxidations are established in synthetic chemistry. In contrast, their use in reductive chemistry is rare. Deazaflavins with a much lower reduction potential are even better suited for reductive chemistry rendering also deazaflavin semiquinones as strong reductants. However, no direct evidence exists for the involvement of these radical species in reductive processes. Here, we synthesise deazaflavins with different substituents at C5 and demonstrate their photocatalytic activity in the dehalogenation of p-halogenanisoles with best performance under basic conditions. Mechanistic investigations reveal a consecutive photo-induced electron transfer via the semiquinone form of the deazaflavin as part of a triplet-correlated radical pair after electron transfer from a sacrificial electron donor to the triplet state. A second electron transfer from the excited semiquinone to p-halogenanisoles triggers the final product formation. This study provides first evidence that the reductive power of excited deazaflavin semiquinones can be used in photocatalytic reductive chemistry. Flavins and deazaflavins are well suited for photoredox processes but their application in photoreductions is challenging. Here, the authors provide direct evidence of the high reductive power of excited deazaflavin semiquinones and their application in catalytic photodehalogenations.
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30
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Abstract
Infrared difference spectroscopy probes vibrational changes of proteins upon their perturbation. Compared with other spectroscopic methods, it stands out by its sensitivity to the protonation state, H-bonding, and the conformation of different groups in proteins, including the peptide backbone, amino acid side chains, internal water molecules, or cofactors. In particular, the detection of protonation and H-bonding changes in a time-resolved manner, not easily obtained by other techniques, is one of the most successful applications of IR difference spectroscopy. The present review deals with the use of perturbations designed to specifically change the protein between two (or more) functionally relevant states, a strategy often referred to as reaction-induced IR difference spectroscopy. In the first half of this contribution, I review the technique of reaction-induced IR difference spectroscopy of proteins, with special emphasis given to the preparation of suitable samples and their characterization, strategies for the perturbation of proteins, and methodologies for time-resolved measurements (from nanoseconds to minutes). The second half of this contribution focuses on the spectral interpretation. It starts by reviewing how changes in H-bonding, medium polarity, and vibrational coupling affect vibrational frequencies, intensities, and bandwidths. It is followed by band assignments, a crucial aspect mostly performed with the help of isotopic labeling and site-directed mutagenesis, and complemented by integration and interpretation of the results in the context of the studied protein, an aspect increasingly supported by spectral calculations. Selected examples from the literature, predominately but not exclusively from retinal proteins, are used to illustrate the topics covered in this review.
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31
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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] [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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32
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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] [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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33
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Ghanbarpour A, Nairat M, Nosrati M, Santos EM, Vasileiou C, Dantus M, Borhan B, Geiger JH. Mimicking Microbial Rhodopsin Isomerization in a Single Crystal. J Am Chem Soc 2019; 141:1735-1741. [PMID: 30580520 DOI: 10.1021/jacs.8b12493] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bacteriorhodopsin represents the simplest, and possibly most abundant, phototropic system requiring only a retinal-bound transmembrane protein to convert photons of light to an energy-generating proton gradient. The creation and interrogation of a microbial rhodopsin mimic, based on an orthogonal protein system, would illuminate the design elements required to generate new photoactive proteins with novel function. We describe a microbial rhodopsin mimic, created using a small soluble protein as a template, that specifically photoisomerizes all- trans to 13- cis retinal followed by thermal relaxation to the all- trans isomer, mimicking the bacteriorhodopsin photocycle, in a single crystal. The key element for selective isomerization is a tuned steric interaction between the chromophore and protein, similar to that seen in the microbial rhodopsins. It is further demonstrated that a single mutation converts the system to a protein photoswitch without chromophore photoisomerization or conformational change.
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Affiliation(s)
- Alireza Ghanbarpour
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - Muath Nairat
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - Meisam Nosrati
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - Elizabeth M Santos
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - Chrysoula Vasileiou
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - Marcos Dantus
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - Babak Borhan
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
| | - James H Geiger
- Michigan State University , Department of Chemistry , East Lansing , Michigan 48824 , United States
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