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Nagao R, Yamamoto H, Ogawa H, Ito H, Yamamoto Y, Suzuki T, Kato K, Nakajima Y, Dohmae N, Shen JR. Presence of low-energy chlorophylls d in photosystem I trimer and monomer cores isolated from Acaryochloris sp. NBRC 102871. PHOTOSYNTHESIS RESEARCH 2024; 161:203-212. [PMID: 38935195 DOI: 10.1007/s11120-024-01108-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024]
Abstract
Acaryochloris species belong to a special category of cyanobacteria possessing chlorophyll (Chl) d. One of the photosynthetic characteristics of Acaryochloris marina MBIC11017 is that the absorption spectra of photosystem I (PSI) showed almost no bands and shoulders of low-energy Chls d over 740 nm. In contrast, the absorption spectra of other Acaryochloris species showed a shoulder around 740 nm, suggesting that low-energy Chls d within PSI are diversified among Acaryochloris species. In this study, we purified PSI trimer and monomer cores from Acaryochloris sp. NBRC 102871 and examined their protein and pigment compositions and spectral properties. The protein bands and pigment compositions of the PSI trimer and monomer of NBRC102871 were virtually identical to those of MBIC11017. The absorption spectra of the NBRC102871 PSIs exhibited a shoulder around 740 nm, whereas the fluorescence spectra of PSI trimer and monomer displayed maximum peaks at 754 and 767 nm, respectively. These spectral properties were different from those of MBIC11017, indicating the presence of low-energy Chls d within the NBRC102871 PSIs. Moreover, we analyzed the NBRC102871 genome to identify amino acid sequences of PSI proteins and compared them with those of the A. marina MBIC11017 and MBIC10699 strains whose genomes are available. The results showed that some of the sequences in NBRC102871 were distinct from those in MBIC11017 and MBIC10699. These findings provide insights into the variety of low-energy Chls d with respect to the protein environments of PSI cores among the three Acaryochloris strains.
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Affiliation(s)
- Ryo Nagao
- Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
| | - Haruki Yamamoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
| | - Haruya Ogawa
- Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Hibiki Ito
- Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Yuma Yamamoto
- Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Koji Kato
- Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science, Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
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Shimizu S, Ogawa H, Tsuboshita N, Suzuki T, Kato K, Nakajima Y, Dohmae N, Shen JR, Nagao R. Tight association of CpcL with photosystem I in Anabaena sp. PCC 7120 grown under iron-deficient conditions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148993. [PMID: 37321385 DOI: 10.1016/j.bbabio.2023.148993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 05/23/2023] [Accepted: 06/09/2023] [Indexed: 06/17/2023]
Abstract
Phycobilisomes (PBSs), which are huge pigment-protein complexes displaying distinctive color variations, bind to photosystem cores for excitation-energy transfer. It is known that isolation of supercomplexes consisting of PBSs and photosystem I (PSI) or PBSs and photosystem II is challenging due to weak interactions between PBSs and the photosystem cores. In this study, we succeeded in purifying PSI-monomer-PBS and PSI-dimer-PBS supercomplexes from the cyanobacterium Anabaena sp. PCC 7120 grown under iron-deficient conditions by anion-exchange chromatography, followed by trehalose density gradient centrifugation. The absorption spectra of the two types of supercomplexes showed apparent bands originating from PBSs, and their fluorescence-emission spectra exhibited characteristic peaks of PBSs. Two-dimensional blue-native (BN)/SDS-PAGE of the two samples showed a band of CpcL, which is a linker protein of PBS, in addition to PsaA/B. Since interactions of PBSs with PSI are easily dissociated during BN-PAGE using thylakoids from this cyanobacterium grown under iron-replete conditions, it is suggested that iron deficiency for Anabaena induces tight association of CpcL with PSI, resulting in the formation of PSI-monomer-PBS and PSI-dimer-PBS supercomplexes. Based on these findings, we discuss interactions of PBSs with PSI in Anabaena.
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Affiliation(s)
- Shota Shimizu
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Haruya Ogawa
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoki Tsuboshita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Ryo Nagao
- Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan.
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Nagao R, Ogawa H, Tsuboshita N, Kato K, Toyofuku R, Tomo T, Shen JR. Isolation and characterization of trimeric and monomeric PSI cores from Acaryochloris marina MBIC11017. PHOTOSYNTHESIS RESEARCH 2023; 157:55-63. [PMID: 37199910 DOI: 10.1007/s11120-023-01025-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 05/05/2023] [Indexed: 05/19/2023]
Abstract
Photosystem I (PSI) catalyzes light-induced electron-transfer reactions and has been observed to exhibit various oligomeric states and different energy levels of chlorophylls (Chls) in response to oligomerization. However, the biochemical and spectroscopic properties of a PSI monomer containing Chls d are not well understood. In this study, we successfully isolated and characterized PSI monomers from the cyanobacterium Acaryochloris marina MBIC11017, and compared their properties with those of the A. marina PSI trimer. The PSI trimers and monomers were prepared using trehalose density gradient centrifugation after anion-exchange and hydrophobic interaction chromatography. The polypeptide composition of the PSI monomer was found to be consistent with that of the PSI trimer. The absorption spectrum of the PSI monomer showed the Qy band of Chl d at 704 nm, which was blue-shifted from the peak at 707 nm observed in the PSI-trimer spectrum. The fluorescence-emission spectrum of the PSI monomer measured at 77 K exhibited a peak at 730 nm without a broad shoulder in the range of 745-780 nm, which was clearly observed in the PSI-trimer spectrum. These spectroscopic properties of the A. marina PSI trimer and monomer suggest different formations of low-energy Chls d between the two types of PSI cores. Based on these findings, we discuss the location of low-energy Chls d in A. marina PSIs.
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Affiliation(s)
- Ryo Nagao
- Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
| | - Haruya Ogawa
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Naoki Tsuboshita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Reona Toyofuku
- Department of Physics, Graduate School of Science, Tokyo University of Science, Tokyo, 162-8601, Japan
| | - Tatsuya Tomo
- Department of Physics, Graduate School of Science, Tokyo University of Science, Tokyo, 162-8601, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
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Nagao R, Kato K, Hamaguchi T, Ueno Y, Tsuboshita N, Shimizu S, Furutani M, Ehira S, Nakajima Y, Kawakami K, Suzuki T, Dohmae N, Akimoto S, Yonekura K, Shen JR. Structure of a monomeric photosystem I core associated with iron-stress-induced-A proteins from Anabaena sp. PCC 7120. Nat Commun 2023; 14:920. [PMID: 36805598 PMCID: PMC9938196 DOI: 10.1038/s41467-023-36504-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 02/03/2023] [Indexed: 02/19/2023] Open
Abstract
Iron-stress-induced-A proteins (IsiAs) are expressed in cyanobacteria under iron-deficient conditions. The cyanobacterium Anabaena sp. PCC 7120 has four isiA genes; however, their binding property and functional roles in PSI are still missing. We analyzed a cryo-electron microscopy structure of a PSI-IsiA supercomplex isolated from Anabaena grown under an iron-deficient condition. The PSI-IsiA structure contains six IsiA subunits associated with the PsaA side of a PSI core monomer. Three of the six IsiA subunits were identified as IsiA1 and IsiA2. The PSI-IsiA structure lacks a PsaL subunit; instead, a C-terminal domain of IsiA2 occupies the position of PsaL, which inhibits the oligomerization of PSI, leading to the formation of a PSI monomer. Furthermore, excitation-energy transfer from IsiAs to PSI appeared with a time constant of 55 ps. These findings provide insights into both the molecular assembly of the Anabaena IsiA family and the functional roles of IsiAs.
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Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan. .,Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
| | - Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.,Structural Biology Division, Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, 679-5198, Japan
| | - Tasuku Hamaguchi
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan.,Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Miyagi, 980-8577, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan.,Institute of Arts and Science, Tokyo University of Science, Tokyo, 162-8601, Japan
| | - Naoki Tsuboshita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Shota Shimizu
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Miyu Furutani
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan
| | - Shigeki Ehira
- Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Tokyo, 192-0397, Japan
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Keisuke Kawakami
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama, 351-0198, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo, 657-8501, Japan.
| | - Koji Yonekura
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Hyogo, 679-5148, Japan. .,Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Miyagi, 980-8577, Japan. .,Advanced Electron Microscope Development Unit, RIKEN-JEOL Collaboration Center, RIKEN Baton Zone Program, Hyogo, 679-5148, Japan.
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
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Kato K, Hamaguchi T, Nagao R, Kawakami K, Ueno Y, Suzuki T, Uchida H, Murakami A, Nakajima Y, Yokono M, Akimoto S, Dohmae N, Yonekura K, Shen JR. Structural basis for the absence of low-energy chlorophylls in a photosystem I trimer from Gloeobacter violaceus. eLife 2022; 11:73990. [PMID: 35404232 PMCID: PMC9000952 DOI: 10.7554/elife.73990] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 02/28/2022] [Indexed: 11/13/2022] Open
Abstract
Photosystem I (PSI) is a multi-subunit pigment-protein complex that functions in light-harvesting and photochemical charge-separation reactions, followed by reduction of NADP to NADPH required for CO2 fixation in photosynthetic organisms. PSI from different photosynthetic organisms has a variety of chlorophylls (Chls), some of which are at lower-energy levels than its reaction center P700, a special pair of Chls, and are called low-energy Chls. However, the sites of low-energy Chls are still under debate. Here, we solved a 2.04-Å resolution structure of a PSI trimer by cryo-electron microscopy from a primordial cyanobacterium Gloeobacter violaceus PCC 7421, which has no low-energy Chls. The structure shows the absence of some subunits commonly found in other cyanobacteria, confirming the primordial nature of this cyanobacterium. Comparison with the known structures of PSI from other cyanobacteria and eukaryotic organisms reveals that one dimeric and one trimeric Chls are lacking in the Gloeobacter PSI. The dimeric and trimeric Chls are named Low1 and Low2, respectively. Low2 is missing in some cyanobacterial and eukaryotic PSIs, whereas Low1 is absent only in Gloeobacter. These findings provide insights into not only the identity of low-energy Chls in PSI, but also the evolutionary changes of low-energy Chls in oxyphototrophs.
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Affiliation(s)
- Koji Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University
| | | | - Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University
| | | | | | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science
| | | | - Akio Murakami
- Graduate School of Science, Kobe University
- Research Center for Inland Seas, Kobe University
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University
| | | | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science
| | - Koji Yonekura
- Biostructural Mechanism Laboratory, RIKEN SPring-8 Center
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
- Advanced Electron Microscope Development Unit, RIKEN-JEOL Collaboration Center, RIKEN Baton Zone Program
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University
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Structure of a tetrameric photosystem I from a glaucophyte alga Cyanophora paradoxa. Nat Commun 2022; 13:1679. [PMID: 35354806 PMCID: PMC8967866 DOI: 10.1038/s41467-022-29303-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/24/2022] [Indexed: 11/08/2022] Open
Abstract
Photosystem I (PSI) is one of the two photosystems functioning in light-energy harvesting, transfer, and electron transfer in photosynthesis. However, the oligomerization state of PSI is variable among photosynthetic organisms. We present a 3.8-Å resolution cryo-electron microscopic structure of tetrameric PSI isolated from the glaucophyte alga Cyanophora paradoxa, which reveals differences with PSI from other organisms in subunit composition and organization. The PSI tetramer is organized in a dimer of dimers with a C2 symmetry. Unlike cyanobacterial PSI tetramers, two of the four monomers are rotated around 90°, resulting in a completely different pattern of monomer-monomer interactions. Excitation-energy transfer among chlorophylls differs significantly between Cyanophora and cyanobacterial PSI tetramers. These structural and spectroscopic features reveal characteristic interactions and excitation-energy transfer in the Cyanophora PSI tetramer, suggesting that the Cyanophora PSI could represent a turning point in the evolution of PSI from prokaryotes to eukaryotes.
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Nagao R, Yokono M, Ueno Y, Nakajima Y, Suzuki T, Kato KH, Tsuboshita N, Dohmae N, Shen JR, Ehira S, Akimoto S. Excitation-energy transfer in heterocysts isolated from the cyanobacterium Anabaena sp. PCC 7120 as studied by time-resolved fluorescence spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148509. [PMID: 34793768 DOI: 10.1016/j.bbabio.2021.148509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 10/06/2021] [Accepted: 11/09/2021] [Indexed: 11/18/2022]
Abstract
Heterocysts are formed in filamentous heterocystous cyanobacteria under nitrogen-starvation conditions, and possess a very low amount of photosystem II (PSII) complexes than vegetative cells. Molecular, morphological, and biochemical characterizations of heterocysts have been investigated; however, excitation-energy dynamics in heterocysts are still unknown. In this study, we examined excitation-energy-relaxation processes of pigment-protein complexes in heterocysts isolated from the cyanobacterium Anabaena sp. PCC 7120. Thylakoid membranes from the heterocysts showed no oxygen-evolving activity under our experimental conditions and no thermoluminescence-glow curve originating from charge recombination of S2QA-. Two dimensional blue-native/SDS-PAGE analysis exhibits tetrameric, dimeric, and monomeric photosystem I (PSI) complexes but almost no dimeric and monomeric PSII complexes in the heterocyst thylakoids. The steady-state fluorescence spectrum of the heterocyst thylakoids at 77 K displays both characteristic PSI fluorescence and unusual PSII fluorescence different from the fluorescence of PSII dimer and monomer complexes. Time-resolved fluorescence spectra at 77 K, followed by fluorescence decay-associated spectra, showed different PSII and PSI fluorescence bands between heterocysts and vegetative thylakoids. Based on these findings, we discuss excitation-energy-transfer mechanisms in the heterocysts.
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Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Hokkaido 060-0819, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Hyogo 657-8501, Japan
| | - Yoshiki Nakajima
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Ka-Ho Kato
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoki Tsuboshita
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Saitama 351-0198, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Shigeki Ehira
- Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Tokyo 192-0397, Japan.
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Hyogo 657-8501, Japan.
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Jangir MM, Chowdhury S, Bhagavatula V. Differential response of photosynthetic apparatus towards alkaline pH treatment in NIES-39 and PCC 7345 strains of Arthrospira platensis. Int Microbiol 2021; 24:219-231. [PMID: 33438119 DOI: 10.1007/s10123-021-00160-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/21/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022]
Abstract
Alkaline stress is one of the severe abiotic stresses, which is not well studied so far, especially among cyanobacteria. To affirm the characteristics of alkaline stress and the subsequent adaptive responses in Arthrospira platensis NIES-39 and Arthrospira platensis PCC 7345, photosynthetic pigments, spectral properties of thylakoids, PSII and PSI activities, and pigment-protein profiles of thylakoids under different pH regimes were examined. The accessory pigments showed a pH-mediated sensitivity. The pigment-protein complexes of thylakoids are also affected, resulting in the altered fluorescence emission profile. At pH 11, a possible shift of the PBsome antenna complex from PSII to PSI is observed. PSII reaction center is found to be more susceptible to alkaline stress in comparison to the PSI. In Arthrospira platensis NIES-39 at pH 11, a drop of 68% in the oxygen evolution with a significant increase of PSI activity by 114% is recorded within 24 h of pH treatment. Alterations in the cellular ultrastructure of Arthrospira platensis NIES-39 at pH 11 were observed, along with the increased number of plastoglobules attached with the thylakoid membranes. Arthrospira platensis NIES-39 is more adaptable to pH variation than Arthrospira platensis PCC 7345.
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Affiliation(s)
- Monika Mahesh Jangir
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, 333031, India
| | - Shibasish Chowdhury
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, 333031, India.
| | - Vani Bhagavatula
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Rajasthan, 333031, India.
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Molecular organizations and function of iron-stress-induced-A protein family in Anabaena sp. PCC 7120. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148327. [PMID: 33069682 DOI: 10.1016/j.bbabio.2020.148327] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/29/2020] [Accepted: 10/13/2020] [Indexed: 11/22/2022]
Abstract
Iron-stress-induced-A proteins (IsiAs) are expressed in cyanobacteria under iron-deficient conditions, and surround photosystem I (PSI) trimer with a ring formation. A cyanobacterium Anabaena sp. PCC 7120 has four isiA genes; however, it is unknown how the IsiAs are associated with PSI. Here we report on molecular organizations and function of the IsiAs in this cyanobacterium. A deletion mutant of the isiA1 gene was constructed, and the four types of thylakoids were prepared from the wild-type (WT) and ΔisiA1 cells under iron-replete (+Fe) and iron-deficient (-Fe) conditions. Immunoblotting analysis exhibits a clear expression of the IsiA1 in the WT-Fe. The PSI-IsiA1 supercomplex is found in the WT-Fe, and excitation-energy transfer from IsiA1 to PSI is verified by time-resolved fluorescence analyses. Instead of the IsiA1, both IsiA2 and IsiA3 are bound to PSI monomer in the ΔisiA1-Fe. These findings provide insights into multiple-expression system of the IsiA family in this cyanobacterium.
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Nagao R, Yokono M, Ueno Y, Shen JR, Akimoto S. Acidic pH-Induced Modification of Energy Transfer in Diatom Fucoxanthin Chlorophyll a/c-Binding Proteins. J Phys Chem B 2020; 124:4919-4923. [DOI: 10.1021/acs.jpcb.0c04231] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryo Nagao
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Yoshifumi Ueno
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Jian-Ren Shen
- Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
| | - Seiji Akimoto
- Graduate School of Science, Kobe University, Kobe 657-8501, Japan
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