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Blain-Hartung M, Johannes von Sass G, Plaickner J, Katz S, Tu Hoang O, Andrea Mroginski M, Esser N, Budisa N, Forest KT, Hildebrandt P. On the Role of a Conserved Tryptophan in the Chromophore Pocket of Cyanobacteriochrome. J Mol Biol 2024; 436:168227. [PMID: 37544357 DOI: 10.1016/j.jmb.2023.168227] [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: 06/21/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/08/2023]
Abstract
The cyanobacteriochrome Slr1393 can be photoconverted between a red (Pr) and green absorbing form (Pg). The recently determined crystal structures of both states suggest a major movement of Trp496 from a stacking interaction with ring D of the phycocyanobilin (PCB) chromophore in Pr to a position outside the chromophore pocket in Pg. Here, we investigated the role of this amino acid during photoconversion in solution using engineered protein variants in which Trp496 was substituted by natural and non-natural amino acids. These variants and the native protein were studied by various spectroscopic techniques (UV-vis absorption, fluorescence, IR, NIR and UV resonance Raman) complemented by theoretical approaches. Trp496 is shown to affect the electronic transition of PCB and to be essential for the thermal equilibrium between Pr and an intermediate state O600. However, Trp496 is not required to stabilize the tilted orientation of ring D in Pr, and does not play a role in the secondary structure changes of Slr1393 during the Pr/Pg transition. The present results confirm the re-orientation of Trp496 upon Pr → Pg conversion, but do not provide evidence of a major change in the microenvironment of this residue. Structural models indicate the penetration of water molecules into the chromophore pocket in both Pr and Pg states and thus water-Trp contacts, which can readily account for the subtle spectral changes between Pr and Pg. Thus, we conclude that reorientation of Trp496 during the Pr-to-Pg photoconversion in solution is not associated with a major change in the dielectric environment in the two states.
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Affiliation(s)
- Matthew Blain-Hartung
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Georg Johannes von Sass
- Technische Universität Berlin, Institut für Chemie, Sekr. CL1, Müller-Breslau-Str.10, D-10623 Berlin, Germany
| | - Julian Plaickner
- Technische Universität Berlin, Institut für Festkörperphysik, Sekr. EW 6-1, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Sagie Katz
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Oanh Tu Hoang
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Maria Andrea Mroginski
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Norbert Esser
- Technische Universität Berlin, Institut für Festkörperphysik, Sekr. EW 6-1, Hardenbergstraße 36, 10623 Berlin, Germany; Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V, Schwarzschildstraße 8, 12489 Berlin, Germany
| | - Nediljko Budisa
- Technische Universität Berlin, Institut für Chemie, Sekr. CL1, Müller-Breslau-Str.10, D-10623 Berlin, Germany; Department of Chemistry, University of Manitoba, 144 Dysart Rd, 360 Parker Building, R3T 2N2 Winnipeg, Manitoba, Canada
| | - Katrina T Forest
- University of Wisconsin-Madison, Department of Bacteriology, 1550 Linden Dr., Madison, WI 53706, USA
| | - Peter Hildebrandt
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany.
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Soulier N, Walters K, Laremore TN, Shen G, Golbeck JH, Bryant DA. Acclimation of the photosynthetic apparatus to low light in a thermophilic Synechococcus sp. strain. Photosynth Res 2022; 153:21-42. [PMID: 35441927 DOI: 10.1007/s11120-022-00918-7] [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] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
Depending upon their growth responses to high and low irradiance, respectively, thermophilic Synechococcus sp. isolates from microbial mats associated with the effluent channels of Mushroom Spring, an alkaline siliceous hot spring in Yellowstone National Park, can be described as either high-light (HL) or low-light (LL) ecotypes. Strains isolated from the bottom of the photic zone grow more rapidly at low irradiance compared to strains isolated from the uppermost layer of the mat, which conversely grow better at high irradiance. The LL-ecotypes develop far-red absorbance and fluorescence emission features after growth in LL. These isolates have a unique gene cluster that encodes a putative cyanobacteriochrome denoted LcyA, a putative sensor histidine kinase; an allophycocyanin (FRL-AP; ApcD4-ApcB3) that absorbs far-red light; and a putative chlorophyll a-binding protein, denoted IsiX, which is homologous to IsiA. The emergence of FRL absorbance in LL-adapted cells of Synechococcus sp. strain A1463 was analyzed in cultures responding to differences in light intensity. The far-red absorbance phenotype arises from expression of a novel antenna complex containing the FRL-AP, ApcD4-ApcB3, which is produced when cells were grown at very low irradiance. Additionally, the two GAF domains of LcyA were shown to bind phycocyanobilin and a [4Fe-4S] cluster, respectively. These ligands potentially enable this photoreceptor to respond to a variety of environmental factors including irradiance, redox potential, and/or oxygen concentration. The products of the gene clusters specific to LL-ecotypes likely facilitate growth in low-light environments through a process called Low-Light Photoacclimation.
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Affiliation(s)
- Nathan Soulier
- Department of Biochemistry and Molecular Biology, S-002 Frear Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Karim Walters
- Department of Biochemistry and Molecular Biology, S-002 Frear Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Tatiana N Laremore
- Proteomics and Mass Spectrometry Core Facility, Huck Institute for the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, S-002 Frear Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, S-002 Frear Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, S-002 Frear Laboratory, The Pennsylvania State University, University Park, PA, 16802, USA.
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3
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Ma Q, Lan DM, Shao AN, Li YH, Zhang XY. Red fluorescent protein from cyanobacteriochrome chromophorylated with phycocyanobilin and biliverdin. Anal Biochem 2022; 642:114557. [PMID: 35092720 DOI: 10.1016/j.ab.2022.114557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 09/27/2021] [Revised: 01/05/2022] [Accepted: 01/11/2022] [Indexed: 12/30/2022]
Abstract
Cyanobacteriochromes are the extended family of phytochrome photosensors characterized in cyanobacteria. Alr1966g2C56A is a cyanobacteriochrome mutant of Alr1966g2 in Nostoc sp. PCC 7120 from freshwater. In this paper, we truncated ten residues in the N-terminus and ten residues in the C-terminus of Alr1966g2C56A and obtained truncated Alr1966g2C46A, termed as Alr1966g2C46A-tr. Alr1966g2C46A-tr binded covalently not only phycocyanobilin but also biliverdin via Cys74 of the conserved CH motif, and showed a significant improvement in binding-PCB efficiency in E. coli, compared with that of untruncated Alr1966g2C56A. We also captured a persistent red fluorescence of Alr1966g2C46A-tr-PCB or Alr1966g2C46A-tr-BV expressed in live E. coli. Thus, Alr1966g2C46A-tr was suitable for the stable red fluorescent probe as a starting material.
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Affiliation(s)
- Qiong Ma
- College of Biological Science and Technology, Hubei Minzu University, Enshi, 445000, China; Key Laboratory of Biologic Resources Protection and Utilization of Hubei Province, Hubei Minzu University, Enshi, 445000, China.
| | - De-Miao Lan
- College of Biological Science and Technology, Hubei Minzu University, Enshi, 445000, China
| | - An-Na Shao
- College of Biological Science and Technology, Hubei Minzu University, Enshi, 445000, China
| | - Ying-Hao Li
- College of Biological Science and Technology, Hubei Minzu University, Enshi, 445000, China
| | - Xiao-Yuan Zhang
- Research Institute Shaoguan Huagong Hig-tech Industry, Shaoguan, 512027, China
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Rockwell NC, Moreno MV, Martin SS, Lagarias JC. Protein-chromophore interactions controlling photoisomerization in red/green cyanobacteriochromes. Photochem Photobiol Sci 2022; 21:471-491. [PMID: 35411484 PMCID: PMC9609751 DOI: 10.1007/s43630-022-00213-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 01/31/2022] [Accepted: 03/21/2022] [Indexed: 10/18/2022]
Abstract
Photoreceptors in the phytochrome superfamily use 15,16-photoisomerization of a linear tetrapyrrole (bilin) chromophore to photoconvert between two states with distinct spectral and biochemical properties. Canonical phytochromes include master regulators of plant growth and development in which light signals trigger interconversion between a red-absorbing 15Z dark-adapted state and a metastable, far-red-absorbing 15E photoproduct state. Distantly related cyanobacteriochromes (CBCRs) carry out a diverse range of photoregulatory functions in cyanobacteria and exhibit considerable spectral diversity. One widespread CBCR subfamily typically exhibits a red-absorbing 15Z dark-adapted state similar to that of phytochrome that gives rise to a distinct green-absorbing 15E photoproduct. This red/green CBCR subfamily also includes red-inactive examples that fail to undergo photoconversion, providing an opportunity to study protein-chromophore interactions that either promote photoisomerization or block it. In this work, we identified a conserved lineage of red-inactive CBCRs. This enabled us to identify three substitutions sufficient to block photoisomerization in photoactive red/green CBCRs. The resulting red-inactive variants faithfully replicated the fluorescence and circular dichroism properties of naturally occurring examples. Converse substitutions restored photoconversion in naturally red-inactive CBCRs. This work thus identifies protein-chromophore interactions that control the fate of the excited-state population in red/green cyanobacteriochromes.
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Affiliation(s)
- Nathan C Rockwell
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA.
| | - Marcus V Moreno
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA
| | - Shelley S Martin
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA
| | - J Clark Lagarias
- Department of Molecular and Cellular Biology, University of California at Davis, Davis, CA, 95616, USA.
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Miyake K, Kimura H, Narikawa R. Identification of significant residues for intermediate accumulation in phycocyanobilin synthesis. Photochem Photobiol Sci 2022; 21:437-46. [PMID: 35394642 DOI: 10.1007/s43630-022-00198-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/28/2022] [Indexed: 10/18/2022]
Abstract
Phycocyanobilin, the primary pigment of both light perception and light-harvesting in cyanobacteria, is synthesized from biliverdin IXα (BV) through intermediate 181, 182-dihydrobiliverdin (181, 182-DHBV) by a phycocyanobilin:ferredoxin oxidoreductase (PcyA). In our previous study, we discovered two PcyA homologs (AmPcyAc and AmPcyAp) derived from Acaryochloris marina MBIC 11017 (A. marina) that exceptionally uses chlorophyll d as the primary photosynthetic pigment, absorbing longer wavelength far-red light than chlorophyll a, the photosynthetic pigment found in most cyanobacteria. Biochemical characterization of the two PcyA homologs identified functional diversification of these two enzymes: AmPcyAc provides 181, 182-DHBV, and PCB to the cyanobacteriochrome (CBCR) photoreceptors, whereas, AmPcyAp specifically provides PCB to the light-harvesting phycobilisome subunit. In this study, we focused on the residues necessary for 181, 182-DHBV supply to the CBCR photoreceptors by AmPcyAc. Based on the SyPcyA structure, we concentrated on the 30 residues that constitute the substrate-binding pocket. Among them, we discovered that Leu151 and Val225 in AmPcyAc were both substituted with isoleucine. During the enzymatic reaction, the SyPcyA variant molecule, possessing V225I and L151I replacements, accumulates the 181, 182-DHBV and supplies it to a CBCR molecule derived from A. marina. It is worth noting that the substitution of Val225 with isoleucine was specifically conserved among the Acaryochloris genus. Collectively, we propose that the specific evolution of PcyA among the Acaryochloris genus may correlate with the acquisition of Chl. d synthetic ability and growth in long-wavelength far-red light environments.
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Jiang SD, sheng Y, Wu XJ, Zhu YL, Li PP. Chromophorylation of a Novel Cyanobacteriochrome GAF Domain from Spirulina and Its Response to Copper Ions. J Microbiol Biotechnol 2021; 31:233-239. [PMID: 33203817 PMCID: PMC9705869 DOI: 10.4014/jmb.2009.09048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/15/2022]
Abstract
Cyanobacteriochromes (CBCRs) are phytochrome-related photoreceptor proteins in cyanobacteria and cover a wide spectral range from ultraviolet to far-red. A single GAF domain that they contain can bind bilin(s) autocatalytically via heterologous recombination and then fluoresce, with potential applications as biomarkers and biosensors. Here, we report that a novel red/green CBCR GAF domain, SPI1085g2 from Spirulina subsalsa, covalently binds both phycocyanobilin (PCB) and phycoerythrobilin (PEB). The PCB-binding GAF domain exhibited canonical red/green photoconversion with weak fluorescence emission. However, the PEB-binding GAF domain, SPI1085g2-PEB, exhibited an intense orange fluorescence (λabs.max = 520 nm, λfluor.max = 555 nm), with a fluorescence quantum yield close to 1.0. The fluorescence of SPI1085g2-PEB was selectively and instantaneously quenched by copper ions in a concentration-dependent manner and exhibited reversibility upon treatment with the metal chelator EDTA. This study identified a novel PEB-binding cyanobacteriochrome-based fluorescent protein with the highest quantum yield reported to date and suggests its potential as a biosensor for the rapid detection of copper ions.
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Affiliation(s)
- Su-Dan Jiang
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China
| | - Yi sheng
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China
| | - Xian-Jun Wu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China,Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 10037, P.R. China,National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 22100, P.R. China,Corresponding authors X. Wu Phone: +86-158-5052-0507 E-mail:
| | - Yong-Li Zhu
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China,Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 10037, P.R. China,National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 22100, P.R. China
| | - Ping-Ping Li
- College of Biology and the Environment, Nanjing Forestry University, Nanjing 20037, P.R. China,Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing 10037, P.R. China,National Positioning Observation Station of Hung-tse Lake Wetland Ecosystem in Jiangsu Province, Hongze, Jiangsu 22100, P.R. China,P. Li Phone: +86-25-8542-7210 E-mail:
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Fushimi K, Narikawa R. Phytochromes and Cyanobacteriochromes: Photoreceptor Molecules Incorporating a Linear Tetrapyrrole Chromophore. Adv Exp Med Biol 2021; 1293:167-87. [PMID: 33398813 DOI: 10.1007/978-981-15-8763-4_10] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this chapter, we summarize the molecular mechanisms of the linear tetrapyrrole-binding photoreceptors, phytochromes, and cyanobacteriochromes. We especially focus on the color-tuning mechanisms and conformational changes during the photoconversion process. Furthermore, we introduce current status of development of the optogenetic tools based on these molecules. Huge repertoire of these photoreceptors with diverse spectral properties would contribute to development of multiplex optogenetic regulation. Among them, the photoreceptors incorporating the biliverdin IXα chromophore is advantageous for in vivo optogenetics because this is intrinsic in the mammalian cells, and absorbs far-red light penetrating into deep mammalian tissues.
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Lim S, Yu Q, Rockwell NC, Martin SS, Lagarias JC, Ames JB. 1H, 13C, and 15N chemical shift assignments of cyanobacteriochrome NpR6012g4 in the green-absorbing photoproduct state. Biomol NMR Assign 2016; 10:157-161. [PMID: 26537963 PMCID: PMC6422171 DOI: 10.1007/s12104-015-9657-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/31/2015] [Indexed: 06/05/2023]
Abstract
Cyanobacteriochromes (CBCRs) are cyanobacterial photosensory proteins with a tetrapyrrole (bilin) chromophore that belong to the phytochrome superfamily. Like phytochromes, CBCRs photoconvert between two photostates with distinct spectral properties. NpR6012g4 from Nostoc punctiforme is a model system for widespread CBCRs with conserved red/green photocycles. Atomic-level structural information for the photoproduct state in this subfamily is not known. Here, we report NMR backbone chemical shift assignments of the light-activated state of NpR6012g4 (BMRB no. 26577) as a first step toward determining its atomic resolution structure.
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Affiliation(s)
- Sunghyuk Lim
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Qinhong Yu
- Department of Chemistry, University of California, Davis, CA, 95616, USA
| | - Nathan C Rockwell
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616, USA
| | - Shelley S Martin
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616, USA
| | - J Clark Lagarias
- Department of Molecular and Cellular Biology, University of California, Davis, CA, 95616, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, CA, 95616, USA.
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Enomoto G, Nomura R, Shimada T, Ni-Ni-Win, Narikawa R, Ikeuchi M. Cyanobacteriochrome SesA is a diguanylate cyclase that induces cell aggregation in Thermosynechococcus. J Biol Chem 2014; 289:24801-9. [PMID: 25059661 DOI: 10.1074/jbc.m114.583674] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyanobacteria have unique photoreceptors, cyanobacteriochromes, that show diverse spectral properties to sense near-UV/visible lights. Certain cyanobacteriochromes have been shown to regulate cellular phototaxis or chromatic acclimation of photosynthetic pigments. Some cyanobacteriochromes have output domains involved in bacterial signaling using a second messenger cyclic dimeric GMP (c-di-GMP), but its role in cyanobacteria remains elusive. Here, we characterize the recombinant Tlr0924 from a thermophilic cyanobacterium Thermosynechococcus elongatus, which was expressed in a cyanobacterial system. The protein reversibly photoconverts between blue- and green-absorbing forms, which is consistent with the protein prepared from Escherichia coli, and has diguanylate cyclase activity, which is enhanced 38-fold by blue light compared with green light. Therefore, Tlr0924 is a blue light-activated diguanylate cyclase. The protein's relatively low affinity (10.5 mM) for Mg(2+), which is essential for diguanylate cyclase activity, suggests that Mg(2+) might also regulate c-di-GMP signaling. Finally, we show that blue light irradiation under low temperature is responsible for Thermosynechococcus vulcanus cell aggregation, which is abolished when tlr0924 is disrupted, suggesting that Tlr0924 mediates blue light-induced cell aggregation by producing c-di-GMP. Given our results, we propose the name "sesA (sessility-A)" for tlr0924. This is the first report for cyanobacteriochrome-dependent regulation of a sessile/planktonic lifestyle in cyanobacteria via c-di-GMP.
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Affiliation(s)
- Gen Enomoto
- From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and
| | - Ryouhei Nomura
- Department of Biological Science, Graduate School of Sciences, University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902
| | - Takashi Shimada
- the Life Science Research Center, Shimadzu Corp., 3-1 Kanda-Nishikicho, Chiyoda-ku, Tokyo 108-8639, and
| | - Ni-Ni-Win
- From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and
| | - Rei Narikawa
- From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and PRESTO and
| | - Masahiko Ikeuchi
- From the Department of Life Sciences (Biology), Graduate School of Arts and Sciences, and Department of Biological Science, Graduate School of Sciences, University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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Cornilescu CC, Cornilescu G, Burgie ES, Markley JL, Ulijasz AT, Vierstra RD. Dynamic structural changes underpin photoconversion of a blue/green cyanobacteriochrome between its dark and photoactivated states. J Biol Chem 2013; 289:3055-65. [PMID: 24337572 DOI: 10.1074/jbc.m113.531053] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phytochrome superfamily of photoreceptors exploits reversible light-driven changes in the bilin chromophore to initiate a variety of signaling cascades. The nature of these alterations and how they impact the protein moiety remain poorly resolved and might include several species-specific routes. Here, we provide a detailed picture of photoconversion for the photosensing cGMP phosphodiesterase/adenylyl cyclase/FhlA (GAF) domain from Thermosynechococcus elongatus (Te) PixJ, a member of the cyanobacteriochrome clade. Solution NMR structures of the blue light-absorbing dark state Pb and green light-absorbing photoactivated state Pg, combined with paired crystallographic models, revealed that the bilin and GAF domain dynamically transition via breakage of the C10/Cys-494 thioether bond, opposite rotations of the A and D pyrrole rings, sliding of the bilin in the GAF pocket, and the appearance of an extended region of disorder that includes Cys-494. Changes in GAF domain backbone dynamics were also observed that are likely important for inter-domain signal propagation. Taken together, photoconversion of T. elongatus PixJ from Pb to Pg involves complex structural changes within the GAF domain pocket that transduce light into a mechanical signal, many aspects of which should be relevant to others within the extended phytochrome superfamily.
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Affiliation(s)
- Claudia C Cornilescu
- From the National Magnetic Resonance Facility at Madison, Department of Biochemistry and
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