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Kawato S, Sato S, Kitoh-Nishioka H, Saga Y. Spectral changes of light-harvesting complex 2 lacking B800 bacteriochlorophyll a under neutral pH conditions. Photochem Photobiol Sci 2024:10.1007/s43630-024-00560-3. [PMID: 38564166 DOI: 10.1007/s43630-024-00560-3] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/05/2024] [Indexed: 04/04/2024]
Abstract
Exchange of B800 bacteriochlorophyll (BChl) a in light-harvesting complex 2 (LH2) is promising for a better understanding of the mechanism on intracomplex excitation energy transfer of this protein. Structural and spectroscopic properties of LH2 lacking B800 BChl a (B800-depleted LH2), which is an important intermediate protein in the B800 exchange, will be useful to tackle the energy transfer mechanism in LH2 by the B800 exchange strategy. In this study, we report a unique spectral change of B800-depleted LH2, in which the Qy absorption band of B800 BChl a is automatically recovered under neutral pH conditions. This spectral change was facilitated by factors for destabilization of LH2, namely, a detergent, lauryl dimethylamine N-oxide, and an increase in temperature. Spectral analyses in the preparation of an LH2 variant denoted as B800-recovered LH2 indicated that most BChl a that was released by decomposition of part of B800-depleted LH2 was a source of the production of B800-recovered LH2. Characterization of purified B800-recovered LH2 demonstrated that its spectroscopic and structural features was quite similar to those of native LH2. The current results indicate that the recovery of the B800 Qy band of B800-depleted LH2 originates from the combination of decomposition of part of B800-depleted LH2 and in situ reconstitution of BChl a into the B800 binding pockets of residual B800-depleted LH2, resulting in the formation of stable B800-recovered LH2.
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Affiliation(s)
- Shota Kawato
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Shinichi Sato
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Hirotaka Kitoh-Nishioka
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Yoshitaka Saga
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan.
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Morimoto M, Hirao H, Kondo M, Dewa T, Kimura Y, Wang-Otomo ZY, Asakawa H, Saga Y. Atomic force microscopic analysis of the light-harvesting complex 2 from purple photosynthetic bacterium Thermochromatium tepidum. Photosynth Res 2023:10.1007/s11120-023-01010-4. [PMID: 36930432 DOI: 10.1007/s11120-023-01010-4] [Citation(s) in RCA: 1] [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] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
Structural information on the circular arrangements of repeating pigment-polypeptide subunits in antenna proteins of purple photosynthetic bacteria is a clue to a better understanding of molecular mechanisms for the ring-structure formation and efficient light harvesting of such antennas. Here, we have analyzed the ring structure of light-harvesting complex 2 (LH2) from the thermophilic purple bacterium Thermochromatium tepidum (tepidum-LH2) by atomic force microscopy. The circular arrangement of the tepidum-LH2 subunits was successfully visualized in a lipid bilayer. The average top-to-top distance of the ring structure, which is correlated with the ring size, was 4.8 ± 0.3 nm. This value was close to the top-to-top distance of the octameric LH2 from Phaeospirillum molischianum (molischianum-LH2) by the previous analysis. Gaussian distribution of the angles of the segments consisting of neighboring subunits in the ring structures of tepidum-LH2 yielded a median of 44°, which corresponds to the angle for the octameric circular arrangement (45°). These results indicate that tepidum-LH2 has a ring structure consisting of eight repeating subunits. The coincidence of an octameric ring structure of tepidum-LH2 with that of molischianum-LH2 is consistent with the homology of amino acid sequences of the polypeptides between tepidum-LH2 and molischianum-LH2.
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Affiliation(s)
- Masayuki Morimoto
- Nanomaterials Research Institute (NanoMaRi), Kanazawa University, Kanazawa, 920-1192, Japan
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192, Japan
| | - Haruna Hirao
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan
| | - Masaharu Kondo
- Graduate School of Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Takehisa Dewa
- Graduate School of Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Yukihiro Kimura
- Graduate School of Agricultural Science, Kobe University, Kobe, 657-8501, Japan
| | | | - Hitoshi Asakawa
- Nanomaterials Research Institute (NanoMaRi), Kanazawa University, Kanazawa, 920-1192, Japan.
- Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, 920-1192, Japan.
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa, 920-1192, Japan.
| | - Yoshitaka Saga
- Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka, 577-8502, Japan.
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Litvín R, Bína D, Herbstová M, Pazderník M, Kotabová E, Gardian Z, Trtílek M, Prášil O, Vácha F. Red-shifted light-harvesting system of freshwater eukaryotic alga Trachydiscus minutus (Eustigmatophyta, Stramenopila). Photosynth Res 2019; 142:137-151. [PMID: 31375979 DOI: 10.1007/s11120-019-00662-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [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: 05/29/2019] [Accepted: 07/22/2019] [Indexed: 06/10/2023]
Abstract
Survival of phototrophic organisms depends on their ability to collect and convert enough light energy to support their metabolism. Phototrophs can extend their absorption cross section by using diverse pigments and by tuning the properties of these pigments via pigment-pigment and pigment-protein interaction. It is well known that some cyanobacteria can grow in heavily shaded habitats by utilizing far-red light harvested with far-red-absorbing chlorophylls d and f. We describe a red-shifted light-harvesting system based on chlorophyll a from a freshwater eustigmatophyte alga Trachydiscus minutus (Eustigmatophyceae, Goniochloridales). A comprehensive characterization of the photosynthetic apparatus of T. minutus is presented. We show that thylakoid membranes of T. minutus contain light-harvesting complexes of several sizes differing in the relative amount of far-red chlorophyll a forms absorbing around 700 nm. The pigment arrangement of the major red-shifted light-harvesting complex is similar to that of the red-shifted antenna of a marine alveolate alga Chromera velia. Evolutionary aspects of the algal far-red light-harvesting complexes are discussed. The presence of these antennas in eustigmatophyte algae opens up new ways to modify organisms of this promising group for effective use of far-red light in mass cultures.
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Affiliation(s)
- Radek Litvín
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Biology Centre, The Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - David Bína
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic.
- Biology Centre, The Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic.
| | - Miroslava Herbstová
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Biology Centre, The Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Marek Pazderník
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 379 81, Třeboň, Czech Republic
| | - Eva Kotabová
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 379 81, Třeboň, Czech Republic
| | - Zdenko Gardian
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Biology Centre, The Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Martin Trtílek
- PSI (Photon Systems Instruments), spol. s r.o. Drásov 470, 664 24, Drásov, Czech Republic
| | - Ondřej Prášil
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 379 81, Třeboň, Czech Republic
| | - František Vácha
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Biology Centre, The Czech Academy of Sciences, Branišovská 31, 370 05, České Budějovice, Czech Republic
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