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Fischer T, Köhler L, Engel PD, Song C, Gärtner W, Wachtveitl J, Slavov C. Conserved tyrosine in phytochromes controls the photodynamics through steric demand and hydrogen bonding capabilities. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148996. [PMID: 37437858 DOI: 10.1016/j.bbabio.2023.148996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 06/02/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023]
Abstract
Using ultrafast spectroscopy and site-specific mutagenesis, we demonstrate the central role of a conserved tyrosine within the chromophore binding pocket in the forward (Pr → Pfr) photoconversion of phytochromes. Taking GAF1 of the knotless phytochrome All2699g1 from Nostoc as representative member of phytochromes, it was found that the mutations have no influence on the early (<30 ps) dynamics associated with conformational changes of the chromophore in the excited state. Conversely, they drastically impact the extended protein-controlled excited state decay (>100 ps). Thus, the steric demand, position and H-bonding capabilities of the identified tyrosine control the chromophore photoisomerization while leaving the excited state chromophore dynamics unaffected. In effect, this residue operates as an isomerization-steric-gate that tunes the excited state lifetime and the photoreaction efficiency by modulating the available space of the chromophore and by stabilizing the primary intermediate Lumi-R. Understanding the role of such a conserved structural element sheds light on a key aspect of phytochrome functionality and provides a basis for rational design of optimized photoreceptors for biotechnological applications.
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Affiliation(s)
- Tobias Fischer
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
| | - Lisa Köhler
- Institute for Analytical Chemistry, University of Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
| | - Philipp D Engel
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
| | - Chen Song
- Institute for Analytical Chemistry, University of Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
| | - Wolfgang Gärtner
- Institute for Analytical Chemistry, University of Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
| | - Chavdar Slavov
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany; Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, 33620 Tampa, United States of America.
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2
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Kurttila M, Etzl S, Rumfeldt J, Takala H, Galler N, Winkler A, Ihalainen JA. The structural effect between the output module and chromophore-binding domain is a two-way street via the hairpin extension. Photochem Photobiol Sci 2022; 21:1881-1894. [PMID: 35984631 PMCID: PMC9630206 DOI: 10.1007/s43630-022-00265-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/30/2022] [Indexed: 11/23/2022]
Abstract
Signal transduction typically starts with either ligand binding or cofactor activation, eventually affecting biological activities in the cell. In red light-sensing phytochromes, isomerization of the bilin chromophore results in regulation of the activity of diverse output modules. During this process, several structural elements and chemical events influence signal propagation. In our study, we have studied the full-length bacteriophytochrome from Deinococcus radiodurans as well as a previously generated optogenetic tool where the native histidine kinase output module has been replaced with an adenylate cyclase. We show that the composition of the output module influences the stability of the hairpin extension. The hairpin, often referred as the PHY tongue, is one of the central structural elements for signal transduction. It extends from a distinct domain establishing close contacts with the chromophore binding site. If the coupling between these interactions is disrupted, the dynamic range of the enzymatic regulation is reduced. Our study highlights the complex conformational properties of the hairpin extension as a bidirectional link between the chromophore-binding site and the output module, as well as functional properties of diverse output modules.
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Affiliation(s)
- Moona Kurttila
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| | - Stefan Etzl
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/II, 8010, Graz, Austria
| | - Jessica Rumfeldt
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| | - Heikki Takala
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| | - Nadine Galler
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/II, 8010, Graz, Austria
| | - Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/II, 8010, Graz, Austria.
| | - Janne A Ihalainen
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland.
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Influence of the PHY domain on the ms-photoconversion dynamics of a knotless phytochrome. Photochem Photobiol Sci 2022; 21:1627-1636. [PMID: 35687310 DOI: 10.1007/s43630-022-00245-9] [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: 02/03/2022] [Accepted: 05/11/2022] [Indexed: 10/18/2022]
Abstract
The ability of some knotless phytochromes to photoconvert without the PHY domain allows evaluation of the distinct effect of the PHY domain on their photodynamics. Here, we compare the ms dynamics of the single GAF domain (g1) and the GAF-PHY (g1g2) construct of the knotless phytochrome All2699 from cyanobacterium Nostoc punctiforme. While the spectral signatures and occurrence of the intermediates are mostly unchanged by the domain composition, the presence of the PHY domain slows down the early forward and reverse dynamics involving chromophore and protein binding pocket relaxation. We assign this effect to a more restricted binding pocket imprinted by the PHY domain. The photoproduct formation is also slowed down by the presence of the PHY domain but to a lesser extent than the early dynamics. This indicates a rate limiting step within the GAF and not the PHY domain. We further identify a pH dependence of the biphasic photoproduct formation hinting towards a pKa dependent tuning mechanism. Our findings add to the understanding of the role of the individual domains in the photocycle dynamics and provide a basis for engineering of phytochromes towards biotechnological applications.
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Kurttila M, Stucki-Buchli B, Rumfeldt J, Schroeder L, Häkkänen H, Liukkonen A, Takala H, Kottke T, Ihalainen JA. Site-by-site tracking of signal transduction in an azidophenylalanine-labeled bacteriophytochrome with step-scan FTIR spectroscopy. Phys Chem Chem Phys 2021; 23:5615-5628. [PMID: 33656023 DOI: 10.1039/d0cp06553f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Signal propagation in photosensory proteins is a complex and multidimensional event. Unraveling such mechanisms site-specifically in real time is an eligible but a challenging goal. Here, we elucidate the site-specific events in a red-light sensing phytochrome using the unnatural amino acid azidophenylalanine, vibrationally distinguishable from all other protein signals. In canonical phytochromes, signal transduction starts with isomerization of an excited bilin chromophore, initiating a multitude of processes in the photosensory unit of the protein, which eventually control the biochemical activity of the output domain, nanometers away from the chromophore. By implementing the label in prime protein locations and running two-color step-scan FTIR spectroscopy on the Deinococcus radiodurans bacteriophytochrome, we track the signal propagation at three specific sites in the photosensory unit. We show that a structurally switchable hairpin extension, a so-called tongue region, responds to the photoconversion already in microseconds and finalizes its structural changes concomitant with the chromophore, in milliseconds. In contrast, kinetics from the other two label positions indicate that the site-specific changes deviate from the chromophore actions, even though the labels locate in the chromophore vicinity. Several other sites for labeling resulted in impaired photoswitching, low structural stability, or no changes in the difference spectrum, which provides additional information on the inner dynamics of the photosensory unit. Our work enlightens the multidimensionality of the structural changes of proteins under action. The study also shows that the signaling mechanism of phytochromes is accessible in a time-resolved and site-specific approach by azido probes and demonstrates challenges in using these labels.
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Affiliation(s)
- Moona Kurttila
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Brigitte Stucki-Buchli
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Jessica Rumfeldt
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Lea Schroeder
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
| | - Heikki Häkkänen
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Alli Liukkonen
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Heikki Takala
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Tilman Kottke
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
| | - Janne A Ihalainen
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
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Fischer T, Xu Q, Zhao K, Gärtner W, Slavov C, Wachtveitl J. Effect of the PHY Domain on the Photoisomerization Step of the Forward P r →P fr Conversion of a Knotless Phytochrome. Chemistry 2020; 26:17261-17266. [PMID: 32812681 PMCID: PMC7839672 DOI: 10.1002/chem.202003138] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/04/2020] [Indexed: 01/26/2023]
Abstract
Phytochrome photoreceptors operate via photoisomerization of a bound bilin chromophore. Their typical architecture consists of GAF, PAS and PHY domains. Knotless phytochromes lack the PAS domain, while retaining photoconversion abilities, with some being able to photoconvert with just the GAF domain. Therefore, we investigated the ultrafast photoisomerization of the Pr state of a knotless phytochrome to reveal the effect of the PHY domain and its "tongue" region on the transduction of the light signal. We show that the PHY domain does not affect the initial conformational dynamics of the chromophore. However, it significantly accelerates the consecutively induced reorganizational dynamics of the protein, necessary for the progression of the photoisomerization. Consequently, the PHY domain keeps the bilin and its binding pocket in a more reactive conformation, which decreases the extent of protein reorganization required for the chromophore isomerization. Thereby, less energy is lost along nonproductive reaction pathways, resulting in increased efficiency.
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Affiliation(s)
- Tobias Fischer
- Institute of Physical and Theoretical ChemistryGoethe University Frankfurt am MainMax-von-Laue Straße 760438FrankfurtGermany
| | - Qianzhao Xu
- Institute of Analytical ChemistryUniversity of LeipzigLinnéstr. 304103LeipzigGermany
| | - Kai‐Hong Zhao
- Key State Laboratory of Agriculture MicrobiologyHuazhong Agriculture University WuhanShizishan Street, Hongshan DistrictWuhan430070P. R. China
| | - Wolfgang Gärtner
- Institute of Analytical ChemistryUniversity of LeipzigLinnéstr. 304103LeipzigGermany
| | - Chavdar Slavov
- Institute of Physical and Theoretical ChemistryGoethe University Frankfurt am MainMax-von-Laue Straße 760438FrankfurtGermany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical ChemistryGoethe University Frankfurt am MainMax-von-Laue Straße 760438FrankfurtGermany
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Kim Y, Xu QZ, Zhao KH, Gärtner W, Matysik J, Song C. Lyophilization Reveals a Multitude of Structural Conformations in the Chromophore of a Cph2-like Phytochrome. J Phys Chem B 2020; 124:7115-7127. [PMID: 32693592 DOI: 10.1021/acs.jpcb.0c03431] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cyanobacteria sense and respond to various colors of light employing a large number of bilin-based phytochrome-like photoreceptors. All2699 from Nostoc 7120 has three consecutive GAF domains with GAF1 and GAF3 binding a phycocyanobilin chromophore. GAF1, even when expressed independently, can be photoconverted between red-absorbing Pr and far-red-absorbing Pfr states, while the nonphotosensory GAF2 domain is structurally and functionally homologous to the PHY domains in canonical and Cph2-like phytochromes. Here, we characterize possible bilin chromophore conformers using solid-state NMR spectroscopy on the two lyophilized All2699 samples (GAF1-only and GAF1-PHY constructs). On the basis of complete 1H, 13C, and 15N assignments for the chromophore obtained on the two Pr lyophilizates, multiple static conformations of the chromophore in both cases are identified. Moreover, most atoms of the chromophore in the bidomain sample show only subtle changes in the mean chemical shifts relative to those in frozen solution (FS), indicating an optimized interaction of the GAF2 domain with the GAF1-bound chromophore. Our results confirm the conservation of key chromophore-protein interactions and the photoreversibility in both All2699 lyophilizates, offering the possibility to investigate conformational distributions of the heterogeneous chromophore and its functional consequences in phytochromes and other bilin-dependent photoreceptors intractable by the solid-state NMR technique as FSs.
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Affiliation(s)
- Yunmi Kim
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
| | - Qian-Zhao Xu
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.,State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Kai-Hong Zhao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Wolfgang Gärtner
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
| | - Jörg Matysik
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
| | - Chen Song
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany
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The interplay between chromophore and protein determines the extended excited state dynamics in a single-domain phytochrome. Proc Natl Acad Sci U S A 2020; 117:16356-16362. [PMID: 32591422 DOI: 10.1073/pnas.1921706117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Phytochromes are a diverse family of bilin-binding photoreceptors that regulate a wide range of physiological processes. Their photochemical properties make them attractive for applications in optogenetics and superresolution microscopy. Phytochromes undergo reversible photoconversion triggered by the Z ⇄ E photoisomerization about the double bond in the bilin chromophore. However, it is not fully understood at the molecular level how the protein framework facilitates the complex photoisomerization dynamics. We have studied a single-domain bilin-binding photoreceptor All2699g1 (Nostoc sp. PCC 7120) that exhibits photoconversion between the red light-absorbing (Pr) and far red-absorbing (Pfr) states just like canonical phytochromes. We present the crystal structure and examine the photoisomerization mechanism of the Pr form as well as the formation of the primary photoproduct Lumi-R using time-resolved spectroscopy and hybrid quantum mechanics/molecular mechanics simulations. We show that the unusually long excited state lifetime (broad lifetime distribution centered at ∼300 picoseconds) is due to the interactions between the isomerizing pyrrole ring D and an adjacent conserved Tyr142. The decay kinetics shows a strongly distributed character which is imposed by the nonexponential protein dynamics. Our findings offer a mechanistic insight into how the quantum efficiency of the bilin photoisomerization is tuned by the protein environment, thereby providing a structural framework for engineering bilin-based optical agents for imaging and optogenetics applications.
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