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Huber C, Strack M, Schultheiß I, Pielage J, Mechler X, Hornbogen J, Diller R, Frankenberg-Dinkel N. Darkness inhibits autokinase activity of bacterial bathy phytochromes. J Biol Chem 2024; 300:107148. [PMID: 38462162 PMCID: PMC11021371 DOI: 10.1016/j.jbc.2024.107148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 03/12/2024] Open
Abstract
Bathy phytochromes are a subclass of bacterial biliprotein photoreceptors that carry a biliverdin IXα chromophore. In contrast to prototypical phytochromes that adopt a red-light-absorbing Pr ground state, the far-red light-absorbing Pfr-form is the thermally stable ground state of bathy phytochromes. Although the photobiology of bacterial phytochromes has been extensively studied since their discovery in the late 1990s, our understanding of the signal transduction process to the connected transmitter domains, which are often histidine kinases, remains insufficient. Initiated by the analysis of the bathy phytochrome PaBphP from Pseudomonas aeruginosa, we performed a systematic analysis of five different bathy phytochromes with the aim to derive a general statement on the correlation of photostate and autokinase output. While all proteins adopt different Pr/Pfr-fractions in response to red, blue, and far-red light, only darkness leads to a pure or highly enriched Pfr-form, directly correlated with the lowest level of autokinase activity. Using this information, we developed a method to quantitatively correlate the autokinase activity of phytochrome samples with well-defined stationary Pr/Pfr-fractions. We demonstrate that the off-state of the phytochromes is the Pfr-form and that different Pr/Pfr-fractions enable the organisms to fine-tune their kinase output in response to a certain light environment. Furthermore, the output response is regulated by the rate of dark reversion, which differs significantly from 5 s to 50 min half-life. Overall, our study indicates that bathy phytochromes function as sensors of light and darkness, rather than red and far-red light, as originally postulated.
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Affiliation(s)
- Christina Huber
- Department of Microbiology, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Merle Strack
- Department of Physics, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Isabel Schultheiß
- Department of Microbiology, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Julia Pielage
- Department of Microbiology, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Xenia Mechler
- Department of Physics, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Justin Hornbogen
- Department of Physics, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Rolf Diller
- Department of Physics, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Nicole Frankenberg-Dinkel
- Department of Microbiology, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Kaiserslautern, Germany.
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2
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Sihorwala AZ, Lin AJ, Stachowiak JC, Belardi B. Light-Activated Assembly of Connexon Nanopores in Synthetic Cells. J Am Chem Soc 2023; 145:3561-3568. [PMID: 36724060 PMCID: PMC10188233 DOI: 10.1021/jacs.2c12491] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
During developmental processes and wound healing, activation of living cells occurs with spatiotemporal precision and leads to rapid release of soluble molecular signals, allowing communication and coordination between neighbors. Nonliving systems capable of similar responsive release hold great promise for information transfer in materials and site-specific drug delivery. One nonliving system that offers a tunable platform for programming release is synthetic cells. Encased in a lipid bilayer structure, synthetic cells can be outfitted with molecular conduits that span the bilayer and lead to material exchange. While previous work expressing membrane pore proteins in synthetic cells demonstrated content exchange, user-defined control over release has remained elusive. In mammalian cells, connexon nanopore structures drive content release and have garnered significant interest since they can direct material exchange through intercellular contacts. Here, we focus on connexon nanopores and present activated release of material from synthetic cells in a light-sensitive fashion. To do this, we re-engineer connexon nanopores to assemble after post-translational processing by a protease. By encapsulating proteases in light-sensitive liposomes, we show that assembly of nanopores can be triggered by illumination, resulting in rapid release of molecules encapsulated within synthetic cells. Controlling connexon nanopore activity provides an opportunity for initiating communication with extracellular signals and for transferring molecular agents to the cytoplasm of living cells in a rapid, light-guided manner.
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Affiliation(s)
- Ahmed Z Sihorwala
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Alexander J Lin
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Brian Belardi
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
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3
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Lee SJ, Kim TW, Kim JG, Yang C, Yun SR, Kim C, Ren Z, Kumarapperuma I, Kuk J, Moffat K, Yang X, Ihee H. Light-induced protein structural dynamics in bacteriophytochrome revealed by time-resolved x-ray solution scattering. SCIENCE ADVANCES 2022; 8:eabm6278. [PMID: 35622911 PMCID: PMC9140987 DOI: 10.1126/sciadv.abm6278] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 04/13/2022] [Indexed: 05/25/2023]
Abstract
Bacteriophytochromes (BphPs) are photoreceptors that regulate a wide range of biological mechanisms via red light-absorbing (Pr)-to-far-red light-absorbing (Pfr) reversible photoconversion. The structural dynamics underlying Pfr-to-Pr photoconversion in a liquid solution phase are not well understood. We used time-resolved x-ray solution scattering (TRXSS) to capture light-induced structural transitions in the bathy BphP photosensory module of Pseudomonas aeruginosa. Kinetic analysis of the TRXSS data identifies three distinct structural species, which are attributed to lumi-F, meta-F, and Pr, connected by time constants of 95 μs and 21 ms. Structural analysis based on molecular dynamics simulations shows that the light activation of PaBphP accompanies quaternary structural rearrangements from an "II"-framed close form of the Pfr state to an "O"-framed open form of the Pr state in terms of the helical backbones. This study provides mechanistic insights into how modular signaling proteins such as BphPs transmit structural signals over long distances and regulate their downstream biological responses.
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Affiliation(s)
- Sang Jin Lee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Tae Wu Kim
- Department of Chemistry, Mokpo National University, Muan-gun, Jeollanam-do, 58554, Republic of Korea
| | - Jong Goo Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Cheolhee Yang
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - So Ri Yun
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Changin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Zhong Ren
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Indika Kumarapperuma
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Jane Kuk
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Keith Moffat
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Xiaojing Yang
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
- Department of Ophthalmology and Vision Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
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4
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Ultrafast proton-coupled isomerization in the phototransformation of phytochrome. Nat Chem 2022; 14:823-830. [PMID: 35577919 PMCID: PMC9252900 DOI: 10.1038/s41557-022-00944-x] [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] [Received: 10/17/2019] [Accepted: 04/01/2022] [Indexed: 11/08/2022]
Abstract
The biological function of phytochromes is triggered by an ultrafast photoisomerization of the tetrapyrrole chromophore biliverdin between two rings denoted C and D. The mechanism by which this process induces extended structural changes of the protein is unclear. Here we report ultrafast proton-coupled photoisomerization upon excitation of the parent state (Pfr) of bacteriophytochrome Agp2. Transient deprotonation of the chromophore's pyrrole ring D or ring C into a hydrogen-bonded water cluster, revealed by a broad continuum infrared band, is triggered by electronic excitation, coherent oscillations and the sudden electric-field change in the excited state. Subsequently, a dominant fraction of the excited population relaxes back to the Pfr state, while ~35% follows the forward reaction to the photoproduct. A combination of quantum mechanics/molecular mechanics calculations and ultrafast visible and infrared spectroscopies demonstrates how proton-coupled dynamics in the excited state of Pfr leads to a restructured hydrogen-bond environment of early Lumi-F, which is interpreted as a trigger for downstream protein structural changes.
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5
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Wichert N, Witt M, Blume C, Scheper T. Clinical applicability of optogenetic gene regulation. Biotechnol Bioeng 2021; 118:4168-4185. [PMID: 34287844 DOI: 10.1002/bit.27895] [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: 11/24/2020] [Revised: 05/27/2021] [Accepted: 07/13/2021] [Indexed: 11/10/2022]
Abstract
The field of optogenetics is rapidly growing in relevance and number of developed tools. Among other things, the optogenetic repertoire includes light-responsive ion channels and methods for gene regulation. This review will be confined to the optogenetic control of gene expression in mammalian cells as suitable models for clinical applications. Here optogenetic gene regulation might offer an excellent method for spatially and timely regulated gene and protein expression in cell therapeutic approaches. Well-known systems for gene regulation, such as the LOV-, CRY2/CIB-, PhyB/PIF-systems, as well as other, in mammalian cells not yet fully established systems, will be described. Advantages and disadvantages with regard to clinical applications are outlined in detail. Among the many unanswered questions concerning the application of optogenetics, we discuss items such as the use of exogenous chromophores and their effects on the biology of the cells and methods for a gentle, but effective gene transfection method for optogenetic tools for in vivo applications.
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Affiliation(s)
- Nina Wichert
- Insitute of Technical Chemistry, Leibniz University of Hannover, Hannover, Germany
| | - Martin Witt
- Insitute of Technical Chemistry, Leibniz University of Hannover, Hannover, Germany
| | - Cornelia Blume
- Insitute of Technical Chemistry, Leibniz University of Hannover, Hannover, Germany
| | - Thomas Scheper
- Insitute of Technical Chemistry, Leibniz University of Hannover, Hannover, Germany
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6
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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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7
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Lamparter T, Xue P, Elkurdi A, Kaeser G, Sauthof L, Scheerer P, Krauß N. Phytochromes in Agrobacterium fabrum. FRONTIERS IN PLANT SCIENCE 2021; 12:642801. [PMID: 33995441 PMCID: PMC8117939 DOI: 10.3389/fpls.2021.642801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/18/2021] [Indexed: 05/31/2023]
Abstract
The focus of this review is on the phytochromes Agp1 and Agp2 of Agrobacterium fabrum. These are involved in regulation of conjugation, gene transfer into plants, and other effects. Since crystal structures of both phytochromes are known, the phytochrome system of A. fabrum provides a tool for following the entire signal transduction cascade starting from light induced conformational changes to protein interaction and the triggering of DNA transfer processes.
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Affiliation(s)
- Tilman Lamparter
- Botanical Institute, Karlsruhe Institute of Technology KIT, Karlsruhe, Germany
| | - Peng Xue
- Botanical Institute, Karlsruhe Institute of Technology KIT, Karlsruhe, Germany
| | - Afaf Elkurdi
- Botanical Institute, Karlsruhe Institute of Technology KIT, Karlsruhe, Germany
| | - Gero Kaeser
- Botanical Institute, Karlsruhe Institute of Technology KIT, Karlsruhe, Germany
| | - Luisa Sauthof
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Berlin, Germany
| | - Patrick Scheerer
- Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Berlin, Germany
| | - Norbert Krauß
- Botanical Institute, Karlsruhe Institute of Technology KIT, Karlsruhe, Germany
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8
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Schmidt A, Sauthof L, Szczepek M, Lopez MF, Escobar FV, Qureshi BM, Michael N, Buhrke D, Stevens T, Kwiatkowski D, von Stetten D, Mroginski MA, Krauß N, Lamparter T, Hildebrandt P, Scheerer P. Structural snapshot of a bacterial phytochrome in its functional intermediate state. Nat Commun 2018; 9:4912. [PMID: 30464203 PMCID: PMC6249285 DOI: 10.1038/s41467-018-07392-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 10/31/2018] [Indexed: 11/09/2022] Open
Abstract
Phytochromes are modular photoreceptors of plants, bacteria and fungi that use light as a source of information to regulate fundamental physiological processes. Interconversion between the active and inactive states is accomplished by a photoinduced reaction sequence which couples the sensor with the output module. However, the underlying molecular mechanism is yet not fully understood due to the lack of structural data of functionally relevant intermediate states. Here we report the crystal structure of a Meta-F intermediate state of an Agp2 variant from Agrobacterium fabrum. This intermediate, the identity of which was verified by resonance Raman spectroscopy, was formed by irradiation of the parent Pfr state and displays significant reorientations of almost all amino acids surrounding the chromophore. Structural comparisons allow identifying structural motifs that might serve as conformational switch for initiating the functional secondary structure change that is linked to the (de-)activation of these photoreceptors.
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Affiliation(s)
- Andrea Schmidt
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany
| | - Luisa Sauthof
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany
| | - Michal Szczepek
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany
| | - Maria Fernandez Lopez
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany
| | - Francisco Velazquez Escobar
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany
| | - Bilal M Qureshi
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany
- Division of Biological & Environmental Sciences & Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Norbert Michael
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany
| | - David Buhrke
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany
| | - Tammo Stevens
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany
| | - Dennis Kwiatkowski
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany
| | - David von Stetten
- Structural Biology Group, European Synchrotron Radiation Facility, CS 40220 F-38043, Grenoble Cedex 9, France
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation c/o DESY, Notkestrasse 85, Hamburg, D-22607, Germany
| | - Maria Andrea Mroginski
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany
| | - Norbert Krauß
- Karlsruhe Institute of Technology (KIT), Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, D-76131, Germany
| | - Tilman Lamparter
- Karlsruhe Institute of Technology (KIT), Botanical Institute, Fritz-Haber-Weg 4, Karlsruhe, D-76131, Germany
| | - Peter Hildebrandt
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, Berlin, D-10623, Germany.
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, Berlin, D-10117, Germany.
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9
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Ibrahim IM, Wang L, Puthiyaveetil S, Krauß N, Nield J, Allen JF. Oligomeric states in sodium ion-dependent regulation of cyanobacterial histidine kinase-2. PROTOPLASMA 2018; 255:937-952. [PMID: 29290041 PMCID: PMC5904244 DOI: 10.1007/s00709-017-1196-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 12/05/2017] [Indexed: 06/07/2023]
Abstract
Two-component signal transduction systems (TCSs) consist of sensor histidine kinases and response regulators. TCSs mediate adaptation to environmental changes in bacteria, plants, fungi and protists. Histidine kinase 2 (Hik2) is a sensor histidine kinase found in all known cyanobacteria and as chloroplast sensor kinase in eukaryotic algae and plants. Sodium ions have been shown to inhibit the autophosphorylation activity of Hik2 that precedes phosphoryl transfer to response regulators, but the mechanism of inhibition has not been determined. We report on the mechanism of Hik2 activation and inactivation probed by chemical cross-linking and size exclusion chromatography together with direct visualisation of the kinase using negative-stain transmission electron microscopy of single particles. We show that the functional form of Hik2 is a higher-order oligomer such as a hexamer or octamer. Increased NaCl concentration converts the active hexamer into an inactive tetramer. The action of NaCl appears to be confined to the Hik2 kinase domain.
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Affiliation(s)
- Iskander M Ibrahim
- Department of Biochemistry and Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, USA
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Liang Wang
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Sujith Puthiyaveetil
- Department of Biochemistry and Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, USA
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Norbert Krauß
- Botanisches Institut, Karlsruher Institut für Technologie, Karlsruhe, Germany
| | - Jon Nield
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - John F Allen
- Research Department of Genetics, Evolution and Environment, University College London, London, UK.
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10
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Velázquez Escobar F, Buhrke D, Michael N, Sauthof L, Wilkening S, Tavraz NN, Salewski J, Frankenberg-Dinkel N, Mroginski MA, Scheerer P, Friedrich T, Siebert F, Hildebrandt P. Common Structural Elements in the Chromophore Binding Pocket of the Pfr State of Bathy Phytochromes. Photochem Photobiol 2017; 93:724-732. [DOI: 10.1111/php.12742] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/06/2017] [Indexed: 01/17/2023]
Affiliation(s)
| | - David Buhrke
- Institut für Chemie; Technische Universität Berlin; Berlin Germany
| | - Norbert Michael
- Institut für Chemie; Technische Universität Berlin; Berlin Germany
| | - Luisa Sauthof
- Institut für Chemie; Technische Universität Berlin; Berlin Germany
- Institute of Medical Physics and Biophysics (CCO); Group Protein X-ray Crystallography & Signal Transduction; Charité - University Medicine Berlin; Berlin Germany
| | - Svea Wilkening
- Institut für Chemie; Technische Universität Berlin; Berlin Germany
| | | | | | - Nicole Frankenberg-Dinkel
- Fachbereich Biologie; Abt. Mikrobiologie; Technische Universität Kaiserslautern; Kaiserslautern Germany
| | | | - Patrick Scheerer
- Institute of Medical Physics and Biophysics (CCO); Group Protein X-ray Crystallography & Signal Transduction; Charité - University Medicine Berlin; Berlin Germany
| | - Thomas Friedrich
- Institut für Chemie; Technische Universität Berlin; Berlin Germany
| | - Friedrich Siebert
- Institut für Molekulare Medizin und Zellforschung; Sektion Biophysik; Albert-Ludwigs-Universität Freiburg; Freiburg Germany
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11
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Lamparter T, Krauß N, Scheerer P. Phytochromes from Agrobacterium fabrum. Photochem Photobiol 2017; 93:642-655. [DOI: 10.1111/php.12761] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/22/2017] [Indexed: 01/24/2023]
Affiliation(s)
- Tilman Lamparter
- Karlsruhe Institute of Technology (KIT); Botanical Institute; Karlsruhe Germany
| | - Norbert Krauß
- Karlsruhe Institute of Technology (KIT); Botanical Institute; Karlsruhe Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin; Institute of Medical Physics and Biophysics (CC2); Group Protein X-ray Crystallography and Signal Transduction; Berlin Germany
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12
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Kacprzak S, Njimona I, Renz A, Feng J, Reijerse E, Lubitz W, Krauss N, Scheerer P, Nagano S, Lamparter T, Weber S. Intersubunit distances in full-length, dimeric, bacterial phytochrome Agp1, as measured by pulsed electron-electron double resonance (PELDOR) between different spin label positions, remain unchanged upon photoconversion. J Biol Chem 2017; 292:7598-7606. [PMID: 28289094 DOI: 10.1074/jbc.m116.761882] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 03/10/2017] [Indexed: 11/06/2022] Open
Abstract
Bacterial phytochromes are dimeric light-regulated histidine kinases that convert red light into signaling events. Light absorption by the N-terminal photosensory core module (PCM) causes the proteins to switch between two spectrally distinct forms, Pr and Pfr, thus resulting in a conformational change that modulates the C-terminal histidine kinase region. To provide further insights into structural details of photoactivation, we investigated the full-length Agp1 bacteriophytochrome from the soil bacterium Agrobacterium fabrum using a combined spectroscopic and modeling approach. We generated seven mutants suitable for spin labeling to enable application of pulsed EPR techniques. The distances between attached spin labels were measured using pulsed electron-electron double resonance spectroscopy to probe the arrangement of the subunits within the dimer. We found very good agreement of experimental and calculated distances for the histidine-kinase region when both subunits are in a parallel orientation. However, experimental distance distributions surprisingly showed only limited agreement with either parallel- or antiparallel-arranged dimer structures when spin labels were placed into the PCM region. This observation indicates that the arrangements of the PCM subunits in the full-length protein dimer in solution differ significantly from that in the PCM crystals. The pulsed electron-electron double resonance data presented here revealed either no or only minor changes of distance distributions upon Pr-to-Pfr photoconversion.
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Affiliation(s)
- Sylwia Kacprzak
- From the Albert-Ludwigs-Universität Freiburg, Institut für Physikalische Chemie, 79104 Freiburg, Germany,
| | - Ibrahim Njimona
- the Karlsruhe Institute of Technology, Botanical Institute I, 76131 Karlsruhe, Germany
| | - Anja Renz
- From the Albert-Ludwigs-Universität Freiburg, Institut für Physikalische Chemie, 79104 Freiburg, Germany
| | - Juan Feng
- the Karlsruhe Institute of Technology, Botanical Institute I, 76131 Karlsruhe, Germany
| | - Edward Reijerse
- the Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - Wolfgang Lubitz
- the Max Planck Institute for Chemical Energy Conversion, 45470 Mülheim an der Ruhr, Germany
| | - Norbert Krauss
- the Karlsruhe Institute of Technology, Botanical Institute I, 76131 Karlsruhe, Germany
| | - Patrick Scheerer
- the Institut für Medizinische Physik und Biophysik (CC2), Group Protein X-ray Crystallography & Signal Transduction, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany, and
| | - Soshichiro Nagano
- the Justus-Liebig-Universität Giessen, Institut für Pflanzenphysiologie, 35390 Giessen, Germany
| | - Tilman Lamparter
- the Karlsruhe Institute of Technology, Botanical Institute I, 76131 Karlsruhe, Germany
| | - Stefan Weber
- From the Albert-Ludwigs-Universität Freiburg, Institut für Physikalische Chemie, 79104 Freiburg, Germany
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13
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Nagano S, Scheerer P, Zubow K, Michael N, Inomata K, Lamparter T, Krauß N. The Crystal Structures of the N-terminal Photosensory Core Module of Agrobacterium Phytochrome Agp1 as Parallel and Anti-parallel Dimers. J Biol Chem 2016; 291:20674-91. [PMID: 27466363 DOI: 10.1074/jbc.m116.739136] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Indexed: 11/06/2022] Open
Abstract
Agp1 is a canonical biliverdin-binding bacteriophytochrome from the soil bacterium Agrobacterium fabrum that acts as a light-regulated histidine kinase. Crystal structures of the photosensory core modules (PCMs) of homologous phytochromes have provided a consistent picture of the structural changes that these proteins undergo during photoconversion between the parent red light-absorbing state (Pr) and the far-red light-absorbing state (Pfr). These changes include secondary structure rearrangements in the so-called tongue of the phytochrome-specific (PHY) domain and structural rearrangements within the long α-helix that connects the cGMP-specific phosphodiesterase, adenylyl cyclase, and FhlA (GAF) and the PHY domains. We present the crystal structures of the PCM of Agp1 at 2.70 Å resolution and of a surface-engineered mutant of this PCM at 1.85 Å resolution in the dark-adapted Pr states. Whereas in the mutant structure the dimer subunits are in anti-parallel orientation, the wild-type structure contains parallel subunits. The relative orientations between the PAS-GAF bidomain and the PHY domain are different in the two structures, due to movement involving two hinge regions in the GAF-PHY connecting α-helix and the tongue, indicating pronounced structural flexibility that may give rise to a dynamic Pr state. The resolution of the mutant structure enabled us to detect a sterically strained conformation of the chromophore at ring A that we attribute to the tight interaction with Pro-461 of the conserved PRXSF motif in the tongue. Based on this observation and on data from mutants where residues in the tongue region were replaced by alanine, we discuss the crucial roles of those residues in Pr-to-Pfr photoconversion.
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Affiliation(s)
- Soshichiro Nagano
- From the School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Patrick Scheerer
- the Institute of Medical Physics and Biophysics (CC2), Group Protein X-ray Crystallography and Signal Transduction, Charité-Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Kristina Zubow
- From the School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Norbert Michael
- the Institut für Chemie, Technische Universität Berlin, Sekretariat PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Katsuhiko Inomata
- the Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan, and
| | - Tilman Lamparter
- the Botanical Institute, Karlsruhe Institute of Technology (KIT), Kaiserstraße 2, D-76131 Karlsruhe, Germany
| | - Norbert Krauß
- From the School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom, the Botanical Institute, Karlsruhe Institute of Technology (KIT), Kaiserstraße 2, D-76131 Karlsruhe, Germany
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Bai Y, Rottwinkel G, Feng J, Liu Y, Lamparter T. Bacteriophytochromes control conjugation in Agrobacterium fabrum. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 161:192-9. [PMID: 27261700 DOI: 10.1016/j.jphotobiol.2016.05.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/11/2016] [Indexed: 10/21/2022]
Abstract
Bacterial conjugation, the transfer of single stranded plasmid DNA from donor to recipient cell, is mediated through the type IV secretion system. We performed conjugation assays using a transmissible artificial plasmid as reporter. With this assay, conjugation in Agrobacterium fabrum was modulated by the phytochromes Agp1 and Agp2, photoreceptors that are most sensitive in the red region of visible light. In conjugation studies with wild-type donor cells carrying a pBIN-GUSINT plasmid as reporter that lacked the Ti (tumor inducing) plasmid, no conjugation was observed. When either agp1(-) or agp2(-) knockout donor strains were used, plasmid DNA was delivered to the recipient, indicating that both phytochromes suppress conjugation in the wild type donor. In the recipient strains, the loss of Agp1 or Agp2 led to diminished conjugation. When wild type cells with Ti plasmid and pBIN-GUS reporter plasmid were used as donor, a high rate of conjugation was observed. The DNA transfer was down regulated by red or far-red light by a factor of 3.5. With agp1(-) or agp2(-) knockout donor cells, conjugation in the dark was about 10 times lower than with the wild type donor, and with the double knockout donor no conjugation was observed. These results imply that the phytochrome system has evolved to inhibit conjugation in the light. The decrease of conjugation under different temperature correlated with the decrease of phytochrome autophosphorylation.
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Affiliation(s)
- Yingnan Bai
- Karlsruhe Institute of Technology (KIT), Botanical Institute, Kaiserstr. 2, D-76131 Karlsruhe, Germany; University of Electronic Science and Technology of China (UESTC), School of Science and Technology, No. 4, Sections 2, North Jianshe Road, Chengdu 610054, China
| | - Gregor Rottwinkel
- Karlsruhe Institute of Technology (KIT), Botanical Institute, Kaiserstr. 2, D-76131 Karlsruhe, Germany
| | - Juan Feng
- University of Electronic Science and Technology of China (UESTC), School of Science and Technology, No. 4, Sections 2, North Jianshe Road, Chengdu 610054, China
| | - Yiyao Liu
- University of Electronic Science and Technology of China (UESTC), School of Science and Technology, No. 4, Sections 2, North Jianshe Road, Chengdu 610054, China
| | - Tilman Lamparter
- Karlsruhe Institute of Technology (KIT), Botanical Institute, Kaiserstr. 2, D-76131 Karlsruhe, Germany.
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15
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Nagano S. From photon to signal in phytochromes: similarities and differences between prokaryotic and plant phytochromes. JOURNAL OF PLANT RESEARCH 2016; 129:123-135. [PMID: 26818948 DOI: 10.1007/s10265-016-0789-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/03/2016] [Indexed: 06/05/2023]
Abstract
Phytochromes represent a diverse family of red/far-red-light absorbing chromoproteins which are widespread across plants, cyanobacteria, non-photosynthetic bacteria, and more. Phytochromes play key roles in regulating physiological activities in response to light, a critical element in the acclimatization to the environment. The discovery of prokaryotic phytochromes facilitated structural studies which deepened our understanding on the general mechanisms of phytochrome action. An extrapolation of this information to plant phytochromes is justified for universally conserved functional aspects, but it is also true that there are many aspects which are unique to plant phytochromes. Here I summarize some structural studies carried out to date on both prokaryotic and plant phytochromes. I also attempt to identify aspects which are common or unique to plant and prokaryotic phytochromes. Phytochrome themselves, as well as the downstream signaling pathway in plants are more complex than in their prokaryotic counterparts. Thus many structural and functional aspects of plant phytochrome remain unresolved.
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Affiliation(s)
- Soshichiro Nagano
- Institute for Plant Physiology, Justus Liebig University Giessen, Senckenbergstrasse 3, 35390, Giessen, Germany.
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Song C, Lang C, Kopycki J, Hughes J, Matysik J. NMR chemical shift pattern changed by ammonium sulfate precipitation in cyanobacterial phytochrome Cph1. Front Mol Biosci 2015; 2:42. [PMID: 26284254 PMCID: PMC4516977 DOI: 10.3389/fmolb.2015.00042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/06/2015] [Indexed: 11/25/2022] Open
Abstract
Phytochromes are dimeric biliprotein photoreceptors exhibiting characteristic red/far-red photocycles. Full-length cyanobacterial phytochrome Cph1 from Synechocystis 6803 is soluble initially but tends to aggregate in a concentration-dependent manner, hampering attempts to solve the structure using NMR and crystallization methods. Otherwise, the Cph1 sensory module (Cph1Δ2), photochemically indistinguishable from the native protein and used extensively in structural and other studies, can be purified to homogeneity in >10 mg amounts at mM concentrations quite easily. Bulk precipitation of full-length Cph1 by ammonium sulfate (AmS) was expected to allow us to produce samples for solid-state magic-angle spinning (MAS) NMR from dilute solutions before significant aggregation began. It was not clear, however, what effects the process of partial dehydration might have on the molecular structure. Here we test this by running solid-state MAS NMR experiments on AmS-precipitated Cph1Δ2 in its red-absorbing Pr state carrying uniformly 13C/15N-labeled phycocyanobilin (PCB) chromophore. 2D 13C–13C correlation experiments allowed a complete assignment of 13C responses of the chromophore. Upon precipitation, 13C chemical shifts for most of PCB carbons move upfield, in which we found major changes for C4 and C6 atoms associated with the A-ring positioning. Further, the broad spectral lines seen in the AmS 13C spectrum reflect primarily the extensive inhomogeneous broadening presumably due to an increase in the distribution of conformational states in the protein, in which less free water is available to partake in the hydration shells. Our data suggest that the effect of dehydration process indeed leads to changes of electronic structure of the bilin chromophore and a decrease in its mobility within the binding pocket, but not restricted to the protein surface. The extent of the changes induced differs from the freezing process of the solution samples routinely used in previous MAS NMR and crystallographic studies. AmS precipitation might nevertheless provide useful protein structure/functional information for full-length Cph1 in cases where neither X-ray crystallography nor conventional NMR methods are available.
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Affiliation(s)
- Chen Song
- Leids Instituut voor Chemisch Onderzoek, Universiteit Leiden Leiden, Netherlands ; Institut für Analytische Chemie, Fakultät für Chemie and Mineralogie, Universität Leipzig Leipzig, Germany
| | - Christina Lang
- Institut für Pflanzenphysiologie, Justus-Liebig-Universität Gießen Gießen, Germany
| | - Jakub Kopycki
- Institut für Pflanzenphysiologie, Justus-Liebig-Universität Gießen Gießen, Germany
| | - Jon Hughes
- Institut für Pflanzenphysiologie, Justus-Liebig-Universität Gießen Gießen, Germany
| | - Jörg Matysik
- Leids Instituut voor Chemisch Onderzoek, Universiteit Leiden Leiden, Netherlands ; Institut für Analytische Chemie, Fakultät für Chemie and Mineralogie, Universität Leipzig Leipzig, Germany
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Fraikin GY, Strakhovskaya MG, Belenikina NS, Rubin AB. Bacterial photosensory proteins: Regulatory functions and optogenetic applications. Microbiology (Reading) 2015. [DOI: 10.1134/s0026261715040086] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Velazquez Escobar F, Piwowarski P, Salewski J, Michael N, Fernandez Lopez M, Rupp A, Qureshi BM, Scheerer P, Bartl F, Frankenberg-Dinkel N, Siebert F, Andrea Mroginski M, Hildebrandt P. A protonation-coupled feedback mechanism controls the signalling process in bathy phytochromes. Nat Chem 2015; 7:423-30. [DOI: 10.1038/nchem.2225] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 03/02/2015] [Indexed: 11/09/2022]
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19
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Njimona I, Yang R, Lamparter T. Temperature effects on bacterial phytochrome. PLoS One 2014; 9:e109794. [PMID: 25289638 PMCID: PMC4188573 DOI: 10.1371/journal.pone.0109794] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/12/2014] [Indexed: 02/01/2023] Open
Abstract
Bacteriophytochromes (BphPs) are light-sensing regulatory proteins encoded in photosynthetic and non-photosynthetic bacteria. This protein class incorporate bilin as their chromophore, with majority of them bearing a light- regulated His kinase or His kinase related module in the C-terminal. We studied the His kinase actives in the temperature range of 5°C to 40°C on two BphPs, Agp1 from Agrobacterium tumefaciens and Cph1 from cyanobacterium Synechocystis PCC 6803. As reported, the phosphorylation activities of the far red (FR) irradiated form of the holoprotein is stronger than that of the red (R) irradiated form in both phytochromes. We observed for the apoprotein and FR irradiated holoprotein of Agp1 an increase in the phosphorylation activities from 5°C to 25°C and a decrease from 25°C to 40°C. At 5°C the activities of the apoprotein were significantly lower than those of the FR irradiated holoprotein, which was opposite at 40°C. A similar temperature pattern was observed for Cph1, but the maximum of the apoprotein was at 20°C while the maximum of the FR irradiated holoprotein was at 10°C. At 40°C, prolonged R irradiation leads to an irreversible bleaching of Cph1, an effect which depends on the C-terminal His kinase module. A more prominent and reversible temperature effect on spectral properties of Agp1, mediated by the His kinase, has been reported before. His kinases in phytochromes could therefore share similar temperature characteristics. We also found that phytochrome B mutants of Arabidopsis have reduced hypocotyl growth at 37°C in darkness, suggesting that this phytochrome senses the temperature or mediates signal transduction of temperature effects.
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Affiliation(s)
- Ibrahim Njimona
- Karlsruhe Institute of Technology KIT, Botanical Institute, Karlsruhe, Germany
| | - Rui Yang
- Karlsruhe Institute of Technology KIT, Botanical Institute, Karlsruhe, Germany
| | - Tilman Lamparter
- Karlsruhe Institute of Technology KIT, Botanical Institute, Karlsruhe, Germany
- * E-mail:
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20
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Linke M, Yang Y, Zienicke B, Hammam MAS, von Haimberger T, Zacarias A, Inomata K, Lamparter T, Heyne K. Electronic transitions and heterogeneity of the bacteriophytochrome Pr absorption band: An angle balanced polarization resolved femtosecond VIS pump-IR probe study. Biophys J 2014; 105:1756-66. [PMID: 24138851 DOI: 10.1016/j.bpj.2013.08.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 08/13/2013] [Accepted: 08/22/2013] [Indexed: 12/15/2022] Open
Abstract
Photoisomerization of biliverdin (BV) chromophore triggers the photoresponse in native Agp1 bacteriophytochrome. We discuss heterogeneity in phytochrome Pr form to account for the shape of the absorption profile. We investigated different regions of the absorption profile by angle balanced polarization resolved femtosecond VIS pump-IR probe spectroscopy. We studied the Pr form of Agp1 with its natural chromophore and with a sterically locked 18Et-BV (locked Agp1). We followed the dynamics and orientations of the carbonyl stretching vibrations of ring D and ring A in their ground and electronically excited states. Photoisomerization of ring D is reflected by strong signals of the ring D carbonyl vibration. In contrast, orientational data on ring A show no rotation of ring A upon photoexcitation. Orientational data allow excluding a ZZZasa geometry and corroborates a nontwisted ZZZssa geometry of the chromophore. We found no proof for heterogeneity but identified a new, to our knowledge, electronic transition in the absorption profile at 644 nm (S0→S2). Excitation of the S0→S2 transition will introduce a more complex photodynamics compared with S0→S1 transition. Our approach provides fundamental information on disentanglement of absorption profiles, identification of chromophore structures, and determination of molecular groups involved in the photoisomerization process of photoreceptors.
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Affiliation(s)
- Martin Linke
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195 Berlin, Germany
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21
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Nieder JB, Stojković EA, Moffat K, Forest KT, Lamparter T, Bittl R, Kennis JTM. Pigment–Protein Interactions in Phytochromes Probed by Fluorescence Line Narrowing Spectroscopy. J Phys Chem B 2013; 117:14940-50. [DOI: 10.1021/jp409110q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Jana B. Nieder
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Emina A. Stojković
- Department of Biochemistry and Molecular Biology, Center for Advanced
Radiation Sources, and Institute for Biophysical Dynamics, University of Chicago, 920 East 58th Street, Chicago, Illinois 60637, United States
| | - Keith Moffat
- Department of Biochemistry and Molecular Biology, Center for Advanced
Radiation Sources, and Institute for Biophysical Dynamics, University of Chicago, 920 East 58th Street, Chicago, Illinois 60637, United States
| | - Katrina T. Forest
- Department of Bacteriology, University of Wisconsin—Madison, 1550 Linden Drive, Madison, Wisconsin 53706, United States
| | - Tilman Lamparter
- Botany
1, KIT - Karlsruhe Institute of Technology, Kaiserstrasse 2, D 76131 Karlsruhe, Germany
| | - Robert Bittl
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - John T. M. Kennis
- Department of Physics and Astronomy, Biophysics Section, VU University Amsterdam, De Boelelaan 1081, NL-1081 HV Amsterdam, The Netherlands
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Feng Z, Zhang W, Xu J, Gauron C, Ducos B, Vriz S, Volovitch M, Jullien L, Weiss S, Bensimon D. Optical control and study of biological processes at the single-cell level in a live organism. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:072601. [PMID: 23764902 PMCID: PMC3736146 DOI: 10.1088/0034-4885/76/7/072601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Living organisms are made of cells that are capable of responding to external signals by modifying their internal state and subsequently their external environment. Revealing and understanding the spatio-temporal dynamics of these complex interaction networks is the subject of a field known as systems biology. To investigate these interactions (a necessary step before understanding or modelling them) one needs to develop means to control or interfere spatially and temporally with these processes and to monitor their response on a fast timescale (< minute) and with single-cell resolution. In 2012, an EMBO workshop on 'single-cell physiology' (organized by some of us) was held in Paris to discuss those issues in the light of recent developments that allow for precise spatio-temporal perturbations and observations. This review will be largely based on the investigations reported there. We will first present a non-exhaustive list of examples of cellular interactions and developmental pathways that could benefit from these new approaches. We will review some of the novel tools that have been developed for the observation of cellular activity and then discuss the recent breakthroughs in optical super-resolution microscopy that allow for optical observations beyond the diffraction limit. We will review the various means to photo-control the activity of biomolecules, which allow for local perturbations of physiological processes. We will end up this review with a report on the current status of optogenetics: the use of photo-sensitive DNA-encoded proteins as sensitive reporters and efficient actuators to perturb and monitor physiological processes.
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Affiliation(s)
- Zhiping Feng
- Department of Molecular, Cellular and Integrative Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
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Salewski J, Escobar FV, Kaminski S, von Stetten D, Keidel A, Rippers Y, Michael N, Scheerer P, Piwowarski P, Bartl F, Frankenberg-Dinkel N, Ringsdorf S, Gärtner W, Lamparter T, Mroginski MA, Hildebrandt P. Structure of the biliverdin cofactor in the Pfr state of bathy and prototypical phytochromes. J Biol Chem 2013; 288:16800-16814. [PMID: 23603902 DOI: 10.1074/jbc.m113.457531] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Phytochromes act as photoswitches between the red- and far-red absorbing parent states of phytochromes (Pr and Pfr). Plant phytochromes display an additional thermal conversion route from the physiologically active Pfr to Pr. The same reaction pattern is found in prototypical biliverdin-binding bacteriophytochromes in contrast to the reverse thermal transformation in bathy bacteriophytochromes. However, the molecular origin of the different thermal stabilities of the Pfr states in prototypical and bathy bacteriophytochromes is not known. We analyzed the structures of the chromophore binding pockets in the Pfr states of various bathy and prototypical biliverdin-binding phytochromes using a combined spectroscopic-theoretical approach. For the Pfr state of the bathy phytochrome from Pseudomonas aeruginosa, the very good agreement between calculated and experimental Raman spectra of the biliverdin cofactor is in line with important conclusions of previous crystallographic analyses, particularly the ZZEssa configuration of the chromophore and its mode of covalent attachment to the protein. The highly homogeneous chromophore conformation seems to be a unique property of the Pfr states of bathy phytochromes. This is in sharp contrast to the Pfr states of prototypical phytochromes that display conformational equilibria between two sub-states exhibiting small structural differences at the terminal methine bridges A-B and C-D. These differences may mainly root in the interactions of the cofactor with the highly conserved Asp-194 that occur via its carboxylate function in bathy phytochromes. The weaker interactions via the carbonyl function in prototypical phytochromes may lead to a higher structural flexibility of the chromophore pocket opening a reaction channel for the thermal (ZZE → ZZZ) Pfr to Pr back-conversion.
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Affiliation(s)
- Johannes Salewski
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Francisco Velazquez Escobar
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Steve Kaminski
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - David von Stetten
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany; Structural Biology Group, European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Anke Keidel
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Yvonne Rippers
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Norbert Michael
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Patrick Scheerer
- Institute of Medical Physics and Biophysics (CCO), D-10117 Berlin, Germany; AG Protein X-ray Crystallography, D-10117 Berlin, Germany
| | - Patrick Piwowarski
- Institute of Medical Physics and Biophysics (CCO), D-10117 Berlin, Germany; AG Spectroscopy, Charité-University Medicine Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Franz Bartl
- Institute of Medical Physics and Biophysics (CCO), D-10117 Berlin, Germany; AG Spectroscopy, Charité-University Medicine Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Nicole Frankenberg-Dinkel
- AG Physiologie der Mikroorganismen, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Simone Ringsdorf
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Wolfgang Gärtner
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Tilman Lamparter
- Institut für Allgemeine Botanik, Karlsruher Institut für Technologie, Kaiserstrasse 2, D-76131 Karlsruhe, Germany
| | - Maria Andrea Mroginski
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
| | - Peter Hildebrandt
- Institut für Chemie, Technische Universität Berlin, Sekr. PC 14, Strasse des 17. Juni 135, D-10623 Berlin, Germany.
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Heyes DJ, Khara B, Sakuma M, Hardman SJO, O'Cualain R, Rigby SEJ, Scrutton NS. Ultrafast red light activation of Synechocystis phytochrome Cph1 triggers major structural change to form the Pfr signalling-competent state. PLoS One 2012; 7:e52418. [PMID: 23300666 PMCID: PMC3530517 DOI: 10.1371/journal.pone.0052418] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 11/15/2012] [Indexed: 11/29/2022] Open
Abstract
Phytochromes are dimeric photoreceptors that regulate a range of responses in plants and microorganisms through interconversion of red light-absorbing (Pr) and far-red light-absorbing (Pfr) states. Photoconversion between these states is initiated by light-driven isomerization of a bilin cofactor, which triggers protein structural change. The extent of this change, and how light-driven structural changes in the N-terminal photosensory region are transmitted to the C-terminal regulatory domain to initiate the signalling cascade, is unknown. We have used pulsed electron-electron double resonance (PELDOR) spectroscopy to identify multiple structural transitions in a phytochrome from Synechocystis sp. PCC6803 (Cph1) by measuring distances between nitroxide labels introduced into the protein. We show that monomers in the Cph1 dimer are aligned in a parallel ‘head-to-head’ arrangement and that photoconversion between the Pr and Pfr forms involves conformational change in both the N- and C-terminal domains of the protein. Cryo-trapping and kinetic measurements were used to probe the extent and temporal properties of protein motions for individual steps during photoconversion of Cph1. Formation of the primary photoproduct Lumi-R is not affected by changes in solvent viscosity and dielectric constant. Lumi-R formation occurs at cryogenic temperatures, consistent with their being no major structural reorganization of Cph1 during primary photoproduct formation. All remaining steps in the formation of the Pfr state are affected by solvent viscosity and dielectric constant and occur only at elevated temperatures, implying involvement of a series of long-range solvent-coupled conformational changes in Cph1. We show that signalling is achieved through ultrafast photoisomerization where localized structural change in the GAF domain is transmitted and amplified to cause larger-scale and slower conformational change in the PHY and histidine kinase domains. This hierarchy of timescales and extent of structural change orientates the histidine kinase domain to elicit the desired light-activated biological response.
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Affiliation(s)
- Derren J Heyes
- Manchester Institute of Biotechnology and Photon Science Institute, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
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Bacteriophytochrome controls carotenoid-independent response to photodynamic stress in a non-photosynthetic rhizobacterium, Azospirillum brasilense Sp7. Sci Rep 2012; 2:872. [PMID: 23173079 PMCID: PMC3503143 DOI: 10.1038/srep00872] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 10/26/2012] [Indexed: 11/20/2022] Open
Abstract
Ever since the discovery of the role of bacteriophytochrome (BphP) in inducing carotenoid synthesis in Deinococcus radiodurans in response to light the role of BphPs in other non-photosynthetic bacteria is not clear yet. Azospirillum brasilense, a non-photosynthetic rhizobacterium, harbours a pair of BphPs out of which AbBphP1 is a homolog of AtBphP1 of Agrobacterium tumefaciens. By overexpression, purification, biochemical and spectral characterization we have shown that AbBphP1 is a photochromic bacteriophytochrome. Phenotypic study of the ΔAbBphP1 mutant showed that it is required for the survival of A. brasilense on minimal medium under red light. The mutant also showed reduced chemotaxis towards dicarboxylates and increased sensitivity to the photooxidative stress. Unlike D. radiodurans, AbBphP1 was not involved in controlling carotenoid synthesis. Proteome analysis of the ΔAbBphP1 indicated that AbBphP1 is involved in inducing a cellular response that enables A. brasilense in regenerating proteins that might be damaged due to photodynamic stress.
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Inomata K. Syntheses of Bilin Chromophores Toward the Investigation of Structure and Function of Phytochromes. HETEROCYCLES 2012. [DOI: 10.3987/rev-12-750] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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27
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Njimona I, Lamparter T. Temperature effects on Agrobacterium phytochrome Agp1. PLoS One 2011; 6:e25977. [PMID: 22043299 PMCID: PMC3197147 DOI: 10.1371/journal.pone.0025977] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/14/2011] [Indexed: 01/18/2023] Open
Abstract
Phytochromes are widely distributed biliprotein photoreceptors with a conserved N-terminal chromophore-binding domain. Most phytochromes bear a light-regulated C-terminal His kinase or His kinase-like region. We investigated the effects of light and temperature on the His kinase activity of the phytochrome Agp1 from Agrobacterium tumefaciens. As in earlier studies, the phosphorylation activity of the holoprotein after far-red irradiation (where the red-light absorbing Pr form dominates) was stronger than that of the holoprotein after red irradiation (where the far red-absorbing Pfr form dominates). Phosphorylation activities of the apoprotein, far red-irradiated holoprotein, and red-irradiated holoprotein decreased when the temperature increased from 25°C to 35°C; at 40°C, almost no kinase activity was detected. The activity of a holoprotein sample incubated at 40°C was nearly completely restored when the temperature returned to 25°C. UV/visible spectroscopy indicated that the protein was not denatured up to 45°C. At 50°C, however, Pfr denatured faster than the dark-adapted sample containing the Pr form of Agp1. The Pr visible spectrum was unaffected by temperatures of 20–45°C, whereas irradiated samples exhibited a clear temperature effect in the 30–40°C range in which prolonged irradiation resulted in the photoconversion of Pfr into a new spectral species termed Prx. Pfr to Prx photoconversion was dependent on the His-kinase module of Agp1; normal photoconversion occurred at 40°C in the mutant Agp1-M15, which lacks the C-terminal His-kinase module, and in a domain-swap mutant in which the His-kinase module of Agp1 is replaced by the His-kinase/response regulator module of the other A. tumefaciens phytochrome, Agp2. The temperature-dependent kinase activity and spectral properties in the physiological temperature range suggest that Agp1 serves as an integrated light and temperature sensor in A. tumefaciens.
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Affiliation(s)
- Ibrahim Njimona
- Botanical Institute, Karlsruhe Institute of Technology (KIT) Campus South, Karlsruhe, Germany
| | - Tilman Lamparter
- Botanical Institute, Karlsruhe Institute of Technology (KIT) Campus South, Karlsruhe, Germany
- * E-mail:
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28
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Spectroscopy and a High-Resolution Crystal Structure of Tyr263 Mutants of Cyanobacterial Phytochrome Cph1. J Mol Biol 2011; 413:115-27. [DOI: 10.1016/j.jmb.2011.08.023] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 08/10/2011] [Accepted: 08/11/2011] [Indexed: 12/14/2022]
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29
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Mailliet J, Psakis G, Feilke K, Sineshchekov V, Essen LO, Hughes J. Spectroscopy and a High-Resolution Crystal Structure of Tyr263 Mutants of Cyanobacterial Phytochrome Cph1. J Mol Biol 2011; 413:115-127. [DOI: https:/doi.org/10.1016/j.jmb.2011.08.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
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Psakis G, Mailliet J, Lang C, Teufel L, Essen LO, Hughes J. Signaling Kinetics of Cyanobacterial Phytochrome Cph1, a Light Regulated Histidine Kinase. Biochemistry 2011; 50:6178-88. [DOI: 10.1021/bi200612d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Georgios Psakis
- Institute for Plant Physiology, Justus Liebig University, Senckenbergstrasse 3, D35390 Giessen, Germany
| | - Jo Mailliet
- Institute for Plant Physiology, Justus Liebig University, Senckenbergstrasse 3, D35390 Giessen, Germany
| | - Christina Lang
- Institute for Plant Physiology, Justus Liebig University, Senckenbergstrasse 3, D35390 Giessen, Germany
| | - Lotte Teufel
- Institute for Plant Physiology, Justus Liebig University, Senckenbergstrasse 3, D35390 Giessen, Germany
| | - Lars-Oliver Essen
- Department of Chemistry, Philipps University, D35032 Marburg, Germany
| | - Jon Hughes
- Institute for Plant Physiology, Justus Liebig University, Senckenbergstrasse 3, D35390 Giessen, Germany
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Elucidating photoinduced structural changes in phytochromes by the combined application of resonance Raman spectroscopy and theoretical methods. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2011.02.038] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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32
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Abstract
Phytochromes are environmental sensors, historically thought of as red/far-red photoreceptors in plants. Their photoperception occurs through a covalently linked tetrapyrrole chromophore, which undergoes a light-dependent conformational change propagated through the protein to a variable output domain. The phytochrome composition is modular, typically consisting of a PAS-GAF-PHY architecture for the N-terminal photosensory core. A collection of three-dimensional structures has uncovered key features, including an unusual figure-of-eight knot, an extension reaching from the PHY domain to the chromophore-binding GAF domain, and a centrally located, long α-helix hypothesized to be crucial for intramolecular signaling. Continuing identification of phytochromes in microbial systems has expanded the assigned sensory abilities of this family out of the red and into the yellow, green, blue, and violet portions of the spectrum. Furthermore, phytochromes acting not as photoreceptors but as redox sensors have been recognized. In addition, architectures other than PAS-GAF-PHY are known, thus revealing phytochromes to be a varied group of sensory receptors evolved to utilize their modular design to perceive a signal and respond accordingly. This review focuses on the structures of bacterial phytochromes and implications for signal transmission. We also discuss the small but growing set of bacterial phytochromes for which a physiological function has been ascertained.
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Affiliation(s)
- Michele E Auldridge
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Nishiyama K, Kamiya A, Hammam MAS, Kinoshita H, Fujinami S, Ukaji Y, Inomata K. Total Syntheses of Sterically Locked Phycocyanobilin Derivatives Bearing a 15Z-antior a 15E-antiCD-Ring Component. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2010. [DOI: 10.1246/bcsj.20100168] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Zienicke B, Chen LY, Khawn H, Hammam MAS, Kinoshita H, Reichert J, Ulrich AS, Inomata K, Lamparter T. Fluorescence of phytochrome adducts with synthetic locked chromophores. J Biol Chem 2010; 286:1103-13. [PMID: 21071442 DOI: 10.1074/jbc.m110.155143] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We performed steady state fluorescence measurements with phytochromes Agp1 and Agp2 of Agrobacterium tumefaciens and three mutants in which photoconversion is inhibited. These proteins were assembled with the natural chromophore biliverdin (BV), with phycoerythrobilin (PEB), which lacks a double bond in the ring C-D-connecting methine bridge, and with synthetic bilin derivatives in which the ring C-D-connecting methine bridge is locked. All PEB and locked chromophore adducts are photoinactive. According to fluorescence quantum yields, the adducts may be divided into four different groups: wild type BV adducts exhibiting a weak fluorescence, mutant BV adducts with about 10-fold enhanced fluorescence, adducts with locked chromophores in which the fluorescence quantum yields are around 0.02, and PEB adducts with a high quantum yield of around 0.5. Thus, the strong fluorescence of the PEB adducts is not reached by the locked chromophore adducts, although the photoconversion energy dissipation pathway is blocked. We therefore suggest that ring D of the bilin chromophore, which contributes to the extended π-electron system of the locked chromophores, provides an energy dissipation pathway that is independent on photoconversion.
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Affiliation(s)
- Benjamin Zienicke
- Botanical Institute, Karlsruhe Institute of Technology, Campus South, Kaiserstrasse 2, D-76131 Karlsruhe, Germany
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Shang L, Rockwell NC, Martin SS, Lagarias JC. Biliverdin amides reveal roles for propionate side chains in bilin reductase recognition and in holophytochrome assembly and photoconversion. Biochemistry 2010; 49:6070-82. [PMID: 20565135 DOI: 10.1021/bi100756x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Linear tetrapyrroles (bilins) perform important antioxidant and light-harvesting functions in cells from bacteria to humans. To explore the role of the propionate moieties in bilin metabolism, we report the semisynthesis of mono- and diamides of biliverdin IXalpha and those of its non-natural XIIIalpha isomer. Initially, these were examined as substrates of two types of NADPH-dependent biliverdin reductase, BVR and BvdR, and of the representative ferredoxin-dependent bilin reductase, phycocyanobilin:ferredoxin oxidoreductase (PcyA). Our studies indicate that the NADPH-dependent biliverdin reductases are less accommodating to amidation of the propionic acid side chains of biliverdin IXalpha than PcyA, which does not require free carboxylic acid side chains to yield its phytobilin product, phycocyanobilin. Bilin amides were also assembled with BV-type and phytobilin-type apophytochromes, demonstrating a role for the 8-propionate in the formation of the spectroscopically native P(r) dark states of these biliprotein photosensors. Neither ionizable propionate side chain proved to be essential to primary photoisomerization for both classes of phytochromes, but an unsubstituted 12-propionate was required for full photointerconversion of phytobilin-type phytochrome Cph1. Taken together, these studies provide insight into the roles of the ionizable propionate side chains in substrate discrimination by two bilin reductase families while further underscoring the mechanistic differences between the photoconversions of BV-type and phytobilin-type phytochromes.
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Affiliation(s)
- Lixia Shang
- Department of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, California 95616, USA
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36
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Abstract
Phytochromes are biliprotein photoreceptors that are found in plants, bacteria, and fungi. Prototypical phytochromes have a Pr ground state that absorbs in the red spectral range and is converted by light into the Pfr form, which absorbs longer-wavelength, far-red light. Recently, some bacterial phytochromes have been described that undergo dark conversion of Pr to Pfr and thus have a Pfr ground state. We show here that such so-called bathy phytochromes are widely distributed among bacteria that belong to the order Rhizobiales. We measured in vivo spectral properties and the direction of dark conversion for species which have either one or two phytochrome genes. Agrobacterium tumefaciens C58 contains one bathy phytochrome and a second phytochrome which undergoes dark conversion of Pfr to Pr in vivo. The related species Agrobacterium vitis S4 contains also one bathy phytochrome and another phytochrome with novel spectral properties. Rhizobium leguminosarum 3841, Rhizobium etli CIAT652, and Azorhizobium caulinodans ORS571 contain a single phytochrome of the bathy type, whereas Xanthobacter autotrophicus Py2 contains a single phytochrome with dark conversion of Pfr to Pr. We propose that bathy phytochromes are adaptations to the light regime in the soil. Most bacterial phytochromes are light-regulated histidine kinases, some of which have a C-terminal response regulator subunit on the same protein. According to our phylogenetic studies, the group of phytochromes with this domain arrangement has evolved from a bathy phytochrome progenitor.
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