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Kurttila M, Rumfeldt J, Takala H, Ihalainen JA. The interconnecting hairpin extension "arm": An essential allosteric element of phytochrome activity. Structure 2023; 31:1100-1108.e4. [PMID: 37392739 DOI: 10.1016/j.str.2023.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/23/2023] [Accepted: 06/06/2023] [Indexed: 07/03/2023]
Abstract
In red-light sensing phytochromes, isomerization of the bilin chromophore triggers structural and dynamic changes across multiple domains, ultimately leading to control of the output module (OPM) activity. In between, a hairpin structure, "arm", extends from an interconnecting domain to the chromophore region. Here, by removing this protein segment in a bacteriophytochrome from Deinococcus radiodurans (DrBphP), we show that the arm is crucial for signal transduction. Crystallographic, spectroscopic, and biochemical data indicate that this variant maintains the properties of DrBphP in the resting state. Spectroscopic data also reveal that the armless systems maintain the ability to respond to light. However, there is no subsequent regulation of OPM activity without the arms. Thermal denaturation reveals that the arms stabilize the DrBphP structure. Our results underline the importance of the structurally flexible interconnecting hairpin extensions and describe their central role in the allosteric coupling of phytochromes.
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Affiliation(s)
- Moona Kurttila
- University of Jyvaskyla, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyvaskyla, Finland
| | - Jessica Rumfeldt
- University of Jyvaskyla, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyvaskyla, Finland
| | - Heikki Takala
- University of Jyvaskyla, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyvaskyla, Finland.
| | - Janne A Ihalainen
- University of Jyvaskyla, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyvaskyla, Finland.
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Kurttila M, Stucki-Buchli B, Rumfeldt J, Schroeder L, Häkkänen H, Liukkonen A, Takala H, Kottke T, Ihalainen JA. Site-by-site tracking of signal transduction in an azidophenylalanine-labeled bacteriophytochrome with step-scan FTIR spectroscopy. Phys Chem Chem Phys 2021; 23:5615-5628. [PMID: 33656023 DOI: 10.1039/d0cp06553f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Signal propagation in photosensory proteins is a complex and multidimensional event. Unraveling such mechanisms site-specifically in real time is an eligible but a challenging goal. Here, we elucidate the site-specific events in a red-light sensing phytochrome using the unnatural amino acid azidophenylalanine, vibrationally distinguishable from all other protein signals. In canonical phytochromes, signal transduction starts with isomerization of an excited bilin chromophore, initiating a multitude of processes in the photosensory unit of the protein, which eventually control the biochemical activity of the output domain, nanometers away from the chromophore. By implementing the label in prime protein locations and running two-color step-scan FTIR spectroscopy on the Deinococcus radiodurans bacteriophytochrome, we track the signal propagation at three specific sites in the photosensory unit. We show that a structurally switchable hairpin extension, a so-called tongue region, responds to the photoconversion already in microseconds and finalizes its structural changes concomitant with the chromophore, in milliseconds. In contrast, kinetics from the other two label positions indicate that the site-specific changes deviate from the chromophore actions, even though the labels locate in the chromophore vicinity. Several other sites for labeling resulted in impaired photoswitching, low structural stability, or no changes in the difference spectrum, which provides additional information on the inner dynamics of the photosensory unit. Our work enlightens the multidimensionality of the structural changes of proteins under action. The study also shows that the signaling mechanism of phytochromes is accessible in a time-resolved and site-specific approach by azido probes and demonstrates challenges in using these labels.
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Affiliation(s)
- Moona Kurttila
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Brigitte Stucki-Buchli
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Jessica Rumfeldt
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Lea Schroeder
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
| | - Heikki Häkkänen
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Alli Liukkonen
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Heikki Takala
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
| | - Tilman Kottke
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
| | - Janne A Ihalainen
- University of Jyväskylä, Nanoscience Center, Department of Biological and Environmental Science, 40014 Jyväskylä, Finland.
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Lenngren N, Edlund P, Takala H, Stucki-Buchli B, Rumfeldt J, Peshev I, Häkkänen H, Westenhoff S, Ihalainen JA. Coordination of the biliverdin D-ring in bacteriophytochromes. Phys Chem Chem Phys 2018; 20:18216-18225. [DOI: 10.1039/c8cp01696h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Vibrational spectroscopy and crystallography experiments provide a basis for understanding the isomerization reaction in phytochrome proteins.
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Affiliation(s)
- Nils Lenngren
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
| | - Petra Edlund
- Department of Chemistry and Molecular Biology
- Biochemistry and Biophysics
- University of Gothenburg
- SE-40530 Gothenburg
- Sweden
| | - Heikki Takala
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
- University of Helsinki
| | - Brigitte Stucki-Buchli
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
| | - Jessica Rumfeldt
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
| | - Ivan Peshev
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
| | - Heikki Häkkänen
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
| | - Sebastian Westenhoff
- Department of Chemistry and Molecular Biology
- Biochemistry and Biophysics
- University of Gothenburg
- SE-40530 Gothenburg
- Sweden
| | - Janne A. Ihalainen
- Department of Biological and Environmental Sciences
- Nanoscience Center
- University of Jyväskylä
- Finland
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Sineva EV, Rumfeldt J, Bakulina AY, Halpert JR, Davydov DR. Ligand‐induced conformational changes in cytochrome P450 3A4 detected by luminescence resonance energy transfer (LRET). FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.784.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Elena V Sineva
- Skaggs School of Pharmacy and Pharmaceutical ScienceUCSDLa JollaCA
| | - Jessica Rumfeldt
- Skaggs School of Pharmacy and Pharmaceutical ScienceUCSDLa JollaCA
| | - Anastasia Yu Bakulina
- State Research Center of Virology and Biotechnology “VECTOR”KoltsovoRussian Federation
| | - James R Halpert
- Skaggs School of Pharmacy and Pharmaceutical ScienceUCSDLa JollaCA
| | - Dmitri R Davydov
- Skaggs School of Pharmacy and Pharmaceutical ScienceUCSDLa JollaCA
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