1
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Dey P, Santra S, Ghosh D. Effect of the protein environment on the excited state phenomena in a bacteriophytochrome. Phys Chem Chem Phys 2024; 26:20875-20882. [PMID: 39044617 DOI: 10.1039/d4cp02112f] [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: 07/25/2024]
Abstract
The excited state processes of a bacteriophytochrome are studied using high-level multireference methods. The various non-radiative channels of deactivation are identified for the chromophore. The effects of the protein environment and substituents are elucidated for these excited state processes. It is observed that while the excited states are completely delocalized in the Franck-Condon (FC) region, they acquire significant charge transfer character near the conical intersections. Earlier studies have emphasized the delocalized nature of the excited states in the FC region, which leads to absorption spectra with minimal Stokes shift [Rumyantsev et al., Sci. Rep., 2015, 5, 18348]. The effect of the protein environment on the vertical excitation energies was minimal, while that on the conical intersection (CI) energetics was significant. This may lead one to believe that it is charge transfer driven. However, energy decomposition analysis shows that it is the effect of the dispersion of nearby residues and the steric effect on the rings and substituents that lead to the large effect of proteins on the energetics of the CIs.
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Affiliation(s)
- Pradipta Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Supriyo Santra
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Debashree Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
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2
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Hughes J, Winkler A. New Insight Into Phytochromes: Connecting Structure to Function. ANNUAL REVIEW OF PLANT BIOLOGY 2024; 75:153-183. [PMID: 39038250 DOI: 10.1146/annurev-arplant-070623-110636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Red and far-red light-sensing phytochromes are widespread in nature, occurring in plants, algae, fungi, and prokaryotes. Despite at least a billion years of evolution, their photosensory modules remain structurally and functionally similar. Conversely, nature has found remarkably different ways of transmitting light signals from the photosensor to diverse physiological responses. We summarize key features of phytochrome structure and function and discuss how these are correlated, from how the bilin environment affects the chromophore to how light induces cellular signals. Recent advances in the structural characterization of bacterial and plant phytochromes have resulted in paradigm changes in phytochrome research that we discuss in the context of present-day knowledge. Finally, we highlight questions that remain to be answered and suggest some of the benefits of understanding phytochrome structure and function.
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Affiliation(s)
- Jon Hughes
- Department of Plant Physiology, Justus Liebig University, Giessen, Germany;
- Department of Physics, Free University of Berlin, Berlin, Germany
| | - Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, Graz, Austria;
- BioTechMed-Graz, Graz, Austria
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3
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Nagae T, Fujita Y, Tsuchida T, Kamo T, Seto R, Hamada M, Aoyama H, Sato-Tomita A, Fujisawa T, Eki T, Miyanoiri Y, Ito Y, Soeta T, Ukaji Y, Unno M, Mishima M, Hirose Y. Green/red light-sensing mechanism in the chromatic acclimation photosensor. SCIENCE ADVANCES 2024; 10:eadn8386. [PMID: 38865454 PMCID: PMC11168458 DOI: 10.1126/sciadv.adn8386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 04/26/2024] [Indexed: 06/14/2024]
Abstract
Certain cyanobacteria alter their photosynthetic light absorption between green and red, a phenomenon called complementary chromatic acclimation. The acclimation is regulated by a cyanobacteriochrome-class photosensor that reversibly photoconverts between green-absorbing (Pg) and red-absorbing (Pr) states. Here, we elucidated the structural basis of the green/red photocycle. In the Pg state, the bilin chromophore adopted the extended C15-Z,anti structure within a hydrophobic pocket. Upon photoconversion to the Pr state, the bilin is isomerized to the cyclic C15-E,syn structure, forming a water channel in the pocket. The solvation/desolvation of the bilin causes changes in the protonation state and the stability of π-conjugation at the B ring, leading to a large absorption shift. These results advance our understanding of the enormous spectral diversity of the phytochrome superfamily.
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Affiliation(s)
- Takayuki Nagae
- Department of Molecular Biophysics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Yuya Fujita
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Tatsuya Tsuchida
- Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
| | - Takanari Kamo
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Ryoka Seto
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjomachi, Saga 840-8502, Japan
| | - Masako Hamada
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Hiroshi Aoyama
- Department of Molecular Biophysics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Ayana Sato-Tomita
- Division of Biophysics, Department of Physiology, Jichi Medical University, Yakushiji, Shimotsuke, Tochigi 329-0498, Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjomachi, Saga 840-8502, Japan
| | - Toshihiko Eki
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
| | - Yohei Miyanoiri
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yutaka Ito
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Takahiro Soeta
- Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
| | - Yutaka Ukaji
- Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjomachi, Saga 840-8502, Japan
| | - Masaki Mishima
- Department of Molecular Biophysics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Yuu Hirose
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
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4
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Zhou LJ, Höppner A, Wang YQ, Hou JY, Scheer H, Zhao KH. Crystallographic and biochemical analyses of a far-red allophycocyanin to address the mechanism of the super-red-shift. PHOTOSYNTHESIS RESEARCH 2024:10.1007/s11120-023-01066-2. [PMID: 38182842 DOI: 10.1007/s11120-023-01066-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 12/03/2023] [Indexed: 01/07/2024]
Abstract
Far-red absorbing allophycocyanins (APC), identified in cyanobacteria capable of FRL photoacclimation (FaRLiP) and low-light photoacclimation (LoLiP), absorb far-red light, functioning in energy transfer as light-harvesting proteins. We report an optimized method to obtain high purity far-red absorbing allophycocyanin B, AP-B2, of Chroococcidiopsis thermalis sp. PCC7203 by synthesis in Escherichia coli and an improved purification protocol. The crystal structure of the trimer, (PCB-ApcD5/PCB-ApcB2)3, has been resolved to 2.8 Å. The main difference to conventional APCs absorbing in the 650-670 nm range is a largely flat chromophore with the co-planarity extending, in particular, from rings BCD to ring A. This effectively extends the conjugation system of PCB and contributes to the super-red-shifted absorption of the α-subunit (λmax = 697 nm). On complexation with the β-subunit, it is even further red-shifted (λmax, absorption = 707 nm, λmax, emission = 721 nm). The relevance of ring A for this shift is supported by mutagenesis data. A variant of the α-subunit, I123M, has been generated that shows an intense FR-band already in the absence of the β-subunit, a possible model is discussed. Two additional mechanisms are known to red-shift the chromophore spectrum: lactam-lactim tautomerism and deprotonation of the chromophore that both mechanisms appear inconsistent with our data, leaving this question unresolved.
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Affiliation(s)
- Li-Juan Zhou
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, The People's Republic of China
| | - Astrid Höppner
- Center for Structural Studies, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Yi-Qing Wang
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, The People's Republic of China
| | - Jian-Yun Hou
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, The People's Republic of China
| | - Hugo Scheer
- Department Biologie I, Universität München, Menzinger Str. 67, 80638, Munich, Germany
| | - Kai-Hong Zhao
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, The People's Republic of China.
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5
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Sineshchekov VA. Two Distinct Molecular Types of Phytochrome A in Plants: Evidence of Existence and Implications for Functioning. Int J Mol Sci 2023; 24:8139. [DOI: https:/doi.org/10.3390/ijms24098139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023] Open
Abstract
Phytochrome (phy) system in plants comprising a small number of phytochromes with phyA and phyB as major ones is responsible for acquiring light information in the red—far-red region of the solar spectrum. It provides optimal strategy for plant development under changing light conditions throughout all its life cycle beginning from seed germination and seedling establishment to fruiting and plant senescence. The phyA was shown to participate in the regulation of this cycle which is especially evident at its early stages. It mediates three modes of reactions—the very low and low fluence responses (VLFR and LFR) and the high irradiance responses (HIR). The phyA is the sole light receptor in the far-red spectral region responsible for plant’s survival under a dense plant canopy where light is enriched with the far-red component. Its appearance is believed to be one of the main factors of plants′ successful evolution. So far, it is widely accepted that one molecular phyA species is responsible for its complex functional manifestations. In this review, the evidence of the existence of two distinct phyA types—major, light-labile and soluble phyA′ and minor, relatively light-stable and amphiphilic phyA″—is presented as what may account for the diverse modes of phyA action.
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6
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Chenchiliyan M, Kübel J, Ooi SA, Salvadori G, Mennucci B, Westenhoff S, Maj M. Ground-state heterogeneity and vibrational energy redistribution in bacterial phytochrome observed with femtosecond 2D IR spectroscopy. J Chem Phys 2023; 158:085103. [PMID: 36859103 DOI: 10.1063/5.0135268] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Abstract
Phytochromes belong to a group of photoreceptor proteins containing a covalently bound biliverdin chromophore that inter-converts between two isomeric forms upon photoexcitation. The existence and stability of the photocycle products are largely determined by the protein sequence and the presence of conserved hydrogen-bonding interactions in the vicinity of the chromophore. The vibrational signatures of biliverdin, however, are often weak and obscured under more intense protein bands, limiting spectroscopic studies of its non-transient signals. In this study, we apply isotope-labeling techniques to isolate the vibrational bands from the protein-bound chromophore of the bacterial phytochrome from Deinococcus radiodurans. We elucidate the structure and ultrafast dynamics of the chromophore with 2D infra-red (IR) spectroscopy and molecular dynamics simulations. The carbonyl stretch vibrations of the pyrrole rings show the heterogeneous distribution of hydrogen-bonding structures, which exhibit distinct ultrafast relaxation dynamics. Moreover, we resolve a previously undetected 1678 cm-1 band that is strongly coupled to the A- and D-ring of biliverdin and demonstrate the presence of complex vibrational redistribution pathways between the biliverdin modes with relaxation-assisted measurements of 2D IR cross peaks. In summary, we expect 2D IR spectroscopy to be useful in explaining how point mutations in the protein sequence affect the hydrogen-bonding structure around the chromophore and consequently its ability to photoisomerize to the light-activated states.
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Affiliation(s)
- Manoop Chenchiliyan
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Joachim Kübel
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Saik Ann Ooi
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Giacomo Salvadori
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56126 Pisa, Italy
| | - Benedetta Mennucci
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56126 Pisa, Italy
| | - Sebastian Westenhoff
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Michał Maj
- Department of Chemistry-Ångström Laboratory, Uppsala University, SE-75120 Uppsala, Sweden
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7
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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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8
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Conserved histidine and tyrosine determine spectral responses through the water network in Deinococcus radiodurans phytochrome. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES : OFFICIAL JOURNAL OF THE EUROPEAN PHOTOCHEMISTRY ASSOCIATION AND THE EUROPEAN SOCIETY FOR PHOTOBIOLOGY 2022; 21:1975-1989. [PMID: 35906527 DOI: 10.1007/s43630-022-00272-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/12/2022] [Indexed: 10/16/2022]
Abstract
Phytochromes are red light-sensing photoreceptor proteins that bind a bilin chromophore. Here, we investigate the role of a conserved histidine (H260) and tyrosine (Y263) in the chromophore-binding domain (CBD) of Deinococcus radiodurans phytochrome (DrBphP). Using crystallography, we show that in the H260A variant, the missing imidazole side chain leads to increased water content in the binding pocket. On the other hand, Y263F mutation reduces the water occupancy around the chromophore. Together, these changes in water coordination alter the protonation and spectroscopic properties of the biliverdin. These results pinpoint the importance of this conserved histidine and tyrosine, and the related water network, for the function and applications of phytochromes.
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9
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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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10
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Fischer T, van Wilderen LJGW, Gnau P, Bredenbeck J, Essen LO, Wachtveitl J, Slavov C. Ultrafast Photoconversion Dynamics of the Knotless Phytochrome SynCph2. Int J Mol Sci 2021; 22:ijms221910690. [PMID: 34639031 PMCID: PMC8508867 DOI: 10.3390/ijms221910690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 12/03/2022] Open
Abstract
The family of phytochrome photoreceptors contains proteins with different domain architectures and spectral properties. Knotless phytochromes are one of the three main subgroups classified by their distinct lack of the PAS domain in their photosensory core module, which is in contrast to the canonical PAS-GAF-PHY array. Despite intensive research on the ultrafast photodynamics of phytochromes, little is known about the primary kinetics in knotless phytochromes. Here, we present the ultrafast Pr ⇆ Pfr photodynamics of SynCph2, the best-known knotless phytochrome. Our results show that the excited state lifetime of Pr* (~200 ps) is similar to bacteriophytochromes, but much longer than in most canonical phytochromes. We assign the slow Pr* kinetics to relaxation processes of the chromophore-binding pocket that controls the bilin chromophore’s isomerization step. The Pfr photoconversion dynamics starts with a faster excited state relaxation than in canonical phytochromes, but, despite the differences in the respective domain architectures, proceeds via similar ground state intermediate steps up to Meta-F. Based on our observations, we propose that the kinetic features and overall dynamics of the ultrafast photoreaction are determined to a great extent by the geometrical context (i.e., available space and flexibility) within the binding pocket, while the general reaction steps following the photoexcitation are most likely conserved among the red/far-red phytochromes.
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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;
| | - Luuk J. G. W. van Wilderen
- Institute of Biophysics, Goethe University Frankfurt am Main, Max-von-Laue Straße 1, 60438 Frankfurt, Germany; (L.J.G.W.v.W.); (J.B.)
| | - Petra Gnau
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany; (P.G.); (L.-O.E.)
| | - Jens Bredenbeck
- Institute of Biophysics, Goethe University Frankfurt am Main, Max-von-Laue Straße 1, 60438 Frankfurt, Germany; (L.J.G.W.v.W.); (J.B.)
| | - Lars-Oliver Essen
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany; (P.G.); (L.-O.E.)
- Center for Synthetic Microbiology, Philipps-Universität Marburg, Hans-Meerwein-Straße 6, 35032 Marburg, Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Straße 7, 60438 Frankfurt, Germany;
- Correspondence: (J.W.); (C.S.)
| | - Chavdar Slavov
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Straße 7, 60438 Frankfurt, Germany;
- Correspondence: (J.W.); (C.S.)
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11
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Rumfeldt J, Kurttila M, Takala H, Ihalainen JA. The hairpin extension controls solvent access to the chromophore binding pocket in a bacterial phytochrome: a UV-vis absorption spectroscopy study. Photochem Photobiol Sci 2021; 20:1173-1181. [PMID: 34460093 DOI: 10.1007/s43630-021-00090-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 08/09/2021] [Indexed: 10/20/2022]
Abstract
Solvent access to the protein interior plays an important role in the function of many proteins. Phytochromes contain a specific structural feature, a hairpin extension that appears to relay structural information from the chromophore to the rest of the protein. The extension interacts with amino acids near the chromophore, and hence shields the chromophore from the surrounding solvent. We envision that the detachment of the extension from the protein surface allows solvent exchange reactions in the vicinity of the chromophore. This can facilitate for example, proton transfer processes between solvent and the protein interior. To test this hypothesis, the kinetics of the protonation state of the biliverdin chromophore from Deinococcus radiodurans bacteriophytchrome, and thus, the pH of the surrounding solution, is determined. The observed absorbance changes are related to the solvent access of the chromophore binding pocket, gated by the hairpin extension. We therefore propose a model with an "open" (solvent-exposed, deprotonation-active on a (sub)second time-scale) state and a "closed" (solvent-gated, deprotonation inactive) state, where the hairpin fluctuates slowly between these conformations thereby controlling the deprotonation process of the chromophore on a minute time scale. When the connection between the hairpin and the biliverdin surroundings is destabilized by a point mutation, the amplitude of the deprotonation phase increases considerably. In the absence of the extension, the chromophore deprotonates essentially without any "gating". Hence, we introduce a straightforward method to study the stability and fluctuation of the phytochrome hairpin in its photostationary state. This approach can be extended to other chromophore-protein systems where absorption changes reflect dynamic processes of the protein.
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Affiliation(s)
- Jessica Rumfeldt
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| | - Moona Kurttila
- 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
| | - Janne A Ihalainen
- Nanoscience Center, Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland.
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12
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Takala H, Edlund P, Ihalainen JA, Westenhoff S. Tips and turns of bacteriophytochrome photoactivation. Photochem Photobiol Sci 2021; 19:1488-1510. [PMID: 33107538 DOI: 10.1039/d0pp00117a] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Phytochromes are ubiquitous photosensor proteins, which control the growth, reproduction and movement in plants, fungi and bacteria. Phytochromes switch between two photophysical states depending on the light conditions. In analogy to molecular machines, light absorption induces a series of structural changes that are transduced from the bilin chromophore, through the protein, and to the output domains. Recent progress towards understanding this structural mechanism of signal transduction has been manifold. We describe this progress with a focus on bacteriophytochromes. We describe the mechanism along three structural tiers, which are the chromophore-binding pocket, the photosensory module, and the output domains. We discuss possible interconnections between the tiers and conclude by presenting future directions and open questions. We hope that this review may serve as a compendium to guide future structural and spectroscopic studies designed to understand structural signaling in phytochromes.
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Affiliation(s)
- Heikki Takala
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, Box 35, 40014 Jyvaskyla, Finland. and Department of Anatomy, Faculty of Medicine, University of Helsinki, Box 63, 00014 Helsinki, Finland
| | - Petra Edlund
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden.
| | - Janne A Ihalainen
- Department of Biological and Environmental Science, Nanoscience Center, University of Jyvaskyla, Box 35, 40014 Jyvaskyla, Finland.
| | - Sebastian Westenhoff
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden.
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13
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Wahlgren WY, Golonka D, Westenhoff S, Möglich A. Cryo-Electron Microscopy of Arabidopsis thaliana Phytochrome A in Its Pr State Reveals Head-to-Head Homodimeric Architecture. FRONTIERS IN PLANT SCIENCE 2021; 12:663751. [PMID: 34108981 PMCID: PMC8182759 DOI: 10.3389/fpls.2021.663751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/29/2021] [Indexed: 06/12/2023]
Abstract
Phytochrome photoreceptors regulate vital adaptations of plant development, growth, and physiology depending on the ratio of red and far-red light. The light-triggered Z/E isomerization of a covalently bound bilin chromophore underlies phytochrome photoconversion between the red-absorbing Pr and far-red-absorbing Pfr states. Compared to bacterial phytochromes, the molecular mechanisms of signal propagation to the C-terminal module and its regulation are little understood in plant phytochromes, not least owing to a dearth of structural information. To address this deficit, we studied the Arabidopsis thaliana phytochrome A (AtphyA) at full length by cryo-electron microscopy (cryo-EM). Following heterologous expression in Escherichia coli, we optimized the solvent conditions to overcome protein aggregation and thus obtained photochemically active, near-homogenous AtphyA. We prepared grids for cryo-EM analysis of AtphyA in its Pr state and conducted single-particle analysis. The resulting two-dimensional class averages and the three-dimensional electron density map at 17 Å showed a homodimeric head-to-head assembly of AtphyA. Docking of domain structures into the electron density revealed a separation of the AtphyA homodimer at the junction of its photosensor and effector modules, as reflected in a large void in the middle of map. The overall architecture of AtphyA resembled that of bacterial phytochromes, thus hinting at commonalities in signal transduction and mechanism between these receptors. Our work paves the way toward future studies of the structure, light response, and interactions of full-length phytochromes by cryo-EM.
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Affiliation(s)
- Weixiao Yuan Wahlgren
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - David Golonka
- Lehrstuhl fur Biochemie, Universität Bayreuth, Bayreuth, Germany
| | - Sebastian Westenhoff
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Andreas Möglich
- Lehrstuhl fur Biochemie, Universität Bayreuth, Bayreuth, Germany
- Bayreuth Center for Biochemistry and Molecular Biology, Universität Bayreuth, Bayreuth, Germany
- North-Bavarian NMR Center, Universität Bayreuth, Bayreuth, Germany
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Sineshchekov VA, Bekasova OD. Two Distinct Photoprocesses in Cyanobacterial Bilin Pigments: Energy Migration in Light‐Harvesting Phycobiliproteins versus Photoisomerization in Phytochromes. Photochem Photobiol 2020; 96:750-767. [DOI: https:/doi.org/10.1111/php.13197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 11/17/2019] [Indexed: 12/17/2023]
Abstract
AbstractThe evolution of oxygenic photosynthesis, respiration and photoperception are connected with the appearance of cyanobacteria. The key compounds, which are involved in these processes, are tetrapyrroles: open chain — bilins and cyclic — chlorophylls and heme. The latter are characterized by their covalent bond with the apoprotein resulting in the formation of biliproteins. This type of photoreceptors is unique in that it can perform important and opposite functions—light‐harvesting in photosynthesis with the participation of phycobiliproteins and photoperception mediated by phycochromes and phytochromes. In this review, cyanobacterial phycobiliproteins and phytochrome Cph1 are considered from a comparative point of view. Structural features of these pigments, which provide their contrasting photophysical and photochemical characteristics, are analyzed. The determining factor in the case of energy migration with the participation of phycobiliproteins is blocking the torsional relaxations of the chromophore, its D‐ring, in the excited state and their freedom, in the case of phytochrome photoisomerization. From the energetics point of view, this distinction is preconditioned by the height of the activation barrier for the photoreaction and relaxation in the excited state, which depends on the degree of the chromophore fixation by its protein surroundings.
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Affiliation(s)
| | - Olga D. Bekasova
- Bach Institute of Biochemistry Fundamentals of Biotechnology Federal Research Centre Russian Academy of Sciences Moscow Russia
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15
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Sineshchekov VA, Bekasova OD. Two Distinct Photoprocesses in Cyanobacterial Bilin Pigments: Energy Migration in Light-Harvesting Phycobiliproteins versus Photoisomerization in Phytochromes. Photochem Photobiol 2019; 96:750-767. [PMID: 31869438 DOI: 10.1111/php.13197] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 11/17/2019] [Indexed: 01/29/2023]
Abstract
The evolution of oxygenic photosynthesis, respiration and photoperception are connected with the appearance of cyanobacteria. The key compounds, which are involved in these processes, are tetrapyrroles: open chain - bilins and cyclic - chlorophylls and heme. The latter are characterized by their covalent bond with the apoprotein resulting in the formation of biliproteins. This type of photoreceptors is unique in that it can perform important and opposite functions-light-harvesting in photosynthesis with the participation of phycobiliproteins and photoperception mediated by phycochromes and phytochromes. In this review, cyanobacterial phycobiliproteins and phytochrome Cph1 are considered from a comparative point of view. Structural features of these pigments, which provide their contrasting photophysical and photochemical characteristics, are analyzed. The determining factor in the case of energy migration with the participation of phycobiliproteins is blocking the torsional relaxations of the chromophore, its D-ring, in the excited state and their freedom, in the case of phytochrome photoisomerization. From the energetics point of view, this distinction is preconditioned by the height of the activation barrier for the photoreaction and relaxation in the excited state, which depends on the degree of the chromophore fixation by its protein surroundings.
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Affiliation(s)
| | - Olga D Bekasova
- Bach Institute of Biochemistry, Fundamentals of Biotechnology Federal Research Centre, Russian Academy of Sciences, Moscow, Russia
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16
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González R, Mroginski MA. Fully Quantum Chemical Treatment of Chromophore–Protein Interactions in Phytochromes. J Phys Chem B 2019; 123:9819-9830. [DOI: 10.1021/acs.jpcb.9b08938] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Ronald González
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Maria A. Mroginski
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
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