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Saga Y, Hamanishi K, Kawato S. Letter to the Editor: Removal of B800 Bacteriochlorophyll a from Light-Harvesting Complex 3 of the Purple Photosynthetic Bacterium Rhodoblastus acidophilus. PLANT & CELL PHYSIOLOGY 2024:pcae065. [PMID: 38965038 DOI: 10.1093/pcp/pcae065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/02/2024] [Accepted: 06/11/2024] [Indexed: 07/06/2024]
Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Kohei Hamanishi
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Shota Kawato
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
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2
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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; 23:871-879. [PMID: 38564166 DOI: 10.1007/s43630-024-00560-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [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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3
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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. PHOTOSYNTHESIS RESEARCH 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] [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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Saga Y, Hamanishi K. Effects of Detergents on the Spectral Features of B820 Bacteriochlorophyll a in Light-Harvesting Complex 3. ACS OMEGA 2022; 7:29231-29235. [PMID: 36033670 PMCID: PMC9404518 DOI: 10.1021/acsomega.2c03323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Excitonic coupling of bacteriochlorophyll (BChl) a in light-harvesting (LH) proteins of purple photosynthetic bacteria is key for efficient photon capture and energy transfer. Environmental factors can affect the spectral features of these BChl a pigments and investigating these effects can provide insight into the molecular mechanisms underlying the photosynthetic spectral tuning. The present study analyzes the spectral alterations of the Qy band of B820 BChl a within the LH3 protein in relation to the type and concentration of detergents in the buffer. Changing the detergent from lauryl dimethylamine N-oxide (LDAO) to n-dodecyl-β-d-maltoside (DDM) caused a red shift in the B820 Qy band accompanied by hyperchromism; these spectral alterations were completely reversed by exchanging back from DDM to LDAO. These results reflect the different effects of harsh vs mild detergents on the perturbation of LH3. The B820 Qy band did not change when LDAO or NaCl concentration was altered, suggesting that electrostatic effects by external components have little influence on the spectral features of B820 BChl a in LH3.
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5
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Saga Y, Tanaka A, Yamashita M, Shinoda T, Tomo T, Kimura Y. Spectral Properties of Chlorophyll f in the B800 Cavity of Light-harvesting Complex 2 from the Purple Photosynthetic Bacterium Rhodoblastus acidophilus. Photochem Photobiol 2021; 98:169-174. [PMID: 34293183 DOI: 10.1111/php.13491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 11/29/2022]
Abstract
The interactions of chlorophyll (Chl) and bacteriochlorophyll (BChl) pigments with the polypeptides in photosynthetic light-harvesting proteins are responsible for controlling the absorption energy of (B)Chls in protein matrixes. The binding pocket of B800 BChl a in LH2 proteins, which are peripheral light-harvesting proteins in purple photosynthetic bacteria, is useful for studying such structure-property relationships. We report the reconstitution of Chl f, which has the formyl group at the 2-position, in the B800 cavity of LH2 from the purple bacterium Rhodoblastus acidophilus. The Qy absorption band of Chl f in the B800 cavity was shifted by 14 nm to longer wavelength compared to that of the corresponding five-coordinated monomer in acetone. This redshift was larger than that of Chl a and Chl b. Resonance Raman spectroscopy indicated hydrogen bonding between the 2-formyl group of Chl f and the LH2 polypeptide. These results suggest that this hydrogen bonding contributes to the Qy redshift of Chl f. Furthermore, the Qy redshift of Chl f in the B800 cavity was smaller than that of Chl d. This may have arisen from the different patterns of hydrogen bonding between Chl f and Chl d and/or from the steric hindrance of the 3-vinyl group in Chl f.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Aiko Tanaka
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Madoka Yamashita
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Toshiyuki Shinoda
- Graduate School of Science, Tokyo University of Science, Tokyo, Japan
| | - Tatsuya Tomo
- Graduate School of Science, Tokyo University of Science, Tokyo, Japan
| | - Yukihiro Kimura
- Graduate School of Agricultural Science, Kobe University, Kobe, Japan
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Saga Y, Yamashita M, Masaoka Y, Hidaka T, Imanishi M, Kimura Y, Nagasawa Y. Excitation Energy Transfer from Bacteriochlorophyll b in the B800 Site to B850 Bacteriochlorophyll a in Light-Harvesting Complex 2. J Phys Chem B 2021; 125:2009-2017. [PMID: 33605728 DOI: 10.1021/acs.jpcb.0c09605] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Control of the spectral overlap between energy donors and acceptors provides insight into excitation energy transfer (EET) mechanisms in photosynthetic light-harvesting proteins. Substitution of energy-donating B800 bacteriochlorophyll (BChl) a with other pigments in the light-harvesting complex 2 (LH2) of purple photosynthetic bacteria has been extensively performed; however, most studies on the B800 substitution have focused on the decrease in the spectral overlap integral with energy-accepting B850 BChl a by reconstitution of chlorophylls into the B800 site. Here, we reconstitute BChl b into the B800 site of the LH2 protein from Rhodoblastus acidophilus to increase the spectral overlap with B850 BChl a. BChl b in the B800 site had essentially the same hydrogen-bonding pattern as B800 BChl a, whereas it showed a red-shifted Qy absorption band at 831 nm. The EET rate from BChl b to B850 BChl a in the reconstituted LH2 was similar to that of native LH2 despite the red shift of the Qy band of the energy donor. These results demonstrate the importance of the contribution of the density of excitation states of the B850 circular assembly, which incorporates higher lying optically forbidden states, to intracomplex EET in LH2.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Madoka Yamashita
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yuto Masaoka
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Tsubasa Hidaka
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Michie Imanishi
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yukihiro Kimura
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yutaka Nagasawa
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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7
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In situ formation of photoactive B-ring reduced chlorophyll isomer in photosynthetic protein LH2. Sci Rep 2020; 10:19383. [PMID: 33168889 PMCID: PMC7652862 DOI: 10.1038/s41598-020-76540-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/28/2020] [Indexed: 12/11/2022] Open
Abstract
Natural chlorophylls have a D-ring reduced chlorin π-system; however, no naturally occurring photosynthetically active B-ring reduced chlorins have been reported. Here we report a B-ring reduced chlorin, 17,18-didehydro-bacteriochlorophyll (BChl) a, produced by in situ oxidation of B800 bacteriochlorophyll (BChl) a in a light-harvesting protein LH2 from a purple photosynthetic bacterium Phaeospirillum molischianum. The regioselective oxidation of the B-ring of B800 BChl a is rationalized by its molecular orientation in the protein matrix. The formation of 17,18-didehydro-BChl a produced no change in the local structures and circular arrangement of the LH2 protein. The B-ring reduced 17,18-didehydro-BChl a functions as an energy donor in the LH2 protein. The photoactive B-ring reduced Chl isomer in LH2 will be helpful for understanding the photofunction and evolution of photosynthetic cyclic tetrapyrrole pigments.
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8
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Fukuma T. Improvements in fundamental performance of in-liquid frequency modulation atomic force microscopy. Microscopy (Oxf) 2020; 69:340-349. [PMID: 32780817 DOI: 10.1093/jmicro/dfaa045] [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: 07/01/2020] [Accepted: 07/31/2020] [Indexed: 12/28/2022] Open
Abstract
In-liquid frequency modulation atomic force microscopy (FM-AFM) has been used for visualizing subnanometer-scale surface structures of minerals, organic thin films and biological systems. In addition, three-dimensional atomic force microscopy (3D-AFM) has been developed by combining it with a three-dimensional (3D) tip scanning method. This method enabled the visualization of 3D distributions of water (i.e. hydration structures) and flexible molecular chains at subnanometer-scale resolution. While these applications highlighted the unique capabilities of FM-AFM, its force resolution, speed and stability are not necessarily at a satisfactory level for practical applications. Recently, there have been significant advancements in these fundamental performances. The force resolution was dramatically improved by using a small cantilever, which enabled the imaging of a 3D hydration structure even in pure water and made it possible to directly compare experimental results with simulated ones. In addition, the improved force resolution allowed the enhancement of imaging speed without compromising spatial resolution. To achieve this goal, efforts have been made for improving bandwidth, resonance frequency and/or latency of various components, including a high-speed phase-locked loop (PLL) circuit. With these improvements, now atomic-resolution in-liquid FM-AFM imaging can be performed at ∼1 s/frame. Furthermore, a Si-coating method was found to improve stability and reproducibility of atomic-resolution imaging owing to formation of a stable hydration structure on a tip apex. These improvements have opened up new possibilities of atomic-scale studies on solid-liquid interfacial phenomena by in-liquid FM-AFM.
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Affiliation(s)
- Takeshi Fukuma
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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9
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Pucelik B, Sułek A, Dąbrowski JM. Bacteriochlorins and their metal complexes as NIR-absorbing photosensitizers: properties, mechanisms, and applications. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213340] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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10
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Effects of palladium ions on light-harvesting complex 2 lacking B800 bacteriochlorophyll a. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Niedzwiedzki DM, Swainsbury DJK, Hunter CN. Carotenoid-to-(bacterio)chlorophyll energy transfer in LH2 antenna complexes from Rba. sphaeroides reconstituted with non-native (bacterio)chlorophylls. PHOTOSYNTHESIS RESEARCH 2020; 144:155-169. [PMID: 31350671 PMCID: PMC7203092 DOI: 10.1007/s11120-019-00661-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/16/2019] [Indexed: 05/04/2023]
Abstract
Six variants of the LH2 antenna complex from Rba. sphaeroides, comprising the native B800-B850, B800-free LH2 (B850) and four LH2s with various (bacterio)chlorophylls reconstituted into the B800 site, have been investigated with static and time-resolved optical spectroscopies at room temperature and at 77 K. The study particularly focused on how reconstitution of a non-native (bacterio)chlorophylls affects excitation energy transfer between the naturally bound carotenoid spheroidene and artificially substituted pigments in the B800 site. Results demonstrate there is no apparent trend in the overall energy transfer rate from spheroidene to B850 bacteriochlorophyll a; however, a trend in energy transfer rate from the spheroidene S1 state to Qy of the B800 (bacterio)chlorophylls is noticeable. These outcomes were applied to test the validity of previously proposed energy values of the spheroidene S1 state, supporting a value in the vicinity of 13,400 cm-1 (746 nm).
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Affiliation(s)
- Dariusz M Niedzwiedzki
- Center for Solar Energy and Energy Storage, Washington University, St. Louis, MO, 63130, USA.
- Department of Energy, Environmental & Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
| | - David J K Swainsbury
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
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12
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Saga Y, Yamashita M, Imanishi M, Kimura Y, Masaoka Y, Hidaka T, Nagasawa Y. Reconstitution of 3-Acetyl Chlorophyll a into Light-Harvesting Complex 2 from the Purple Photosynthetic Bacterium Phaeospirillum molischianum. ACS OMEGA 2020; 5:6817-6825. [PMID: 32258917 PMCID: PMC7114761 DOI: 10.1021/acsomega.0c00152] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 03/06/2020] [Indexed: 06/11/2023]
Abstract
The manipulation of B800 bacteriochlorophyll (BChl) a in light-harvesting complex 2 (LH2) from the purple photosynthetic bacterium Phaeospirillum molischianum (molischianum-LH2) provides insight for understanding the energy transfer mechanism and the binding of cyclic tetrapyrroles in LH2 proteins since molischianum-LH2 is one of the two LH2 proteins whose atomic-resolution structures have been determined and is a representative of type-2 LH2 proteins. However, there is no report on the substitution of B800 BChl a in molischianum-LH2. We report the reconstitution of 3-acetyl chlorophyll (AcChl) a, which has a 17,18-dihydroporphyrin skeleton, to the B800 site in molischianum-LH2. The 3-acetyl group in AcChl a formed a hydrogen bond with β'-Thr23 in essentially the same manner as native B800 BChl a, but this hydrogen bond was weaker than that of B800 BChl a. This change can be rationalized by invoking a small distortion in the orientation of the 3-acetyl group in the B800 cavity by dehydrogenation in the B-ring from BChl a. The energy transfer from AcChl a in the B800 site to B850 BChl a was about 5-fold slower than that from native B800 BChl a by a decrease of the spectral overlap between energy-donating AcChl a and energy-accepting B850 BChl a.
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Affiliation(s)
- Yoshitaka Saga
- Department
of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka 577-8502, Osaka, Japan
| | - Madoka Yamashita
- Department
of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka 577-8502, Osaka, Japan
| | - Michie Imanishi
- Graduate
School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yukihiro Kimura
- Graduate
School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yuto Masaoka
- Graduate
School of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Shiga, Japan
| | - Tsubasa Hidaka
- Graduate
School of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Shiga, Japan
| | - Yutaka Nagasawa
- Graduate
School of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Shiga, Japan
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13
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Yoneda Y, Kato D, Kondo M, Nagashima KVP, Miyasaka H, Nagasawa Y, Dewa T. Sequential energy transfer driven by monoexponential dynamics in a biohybrid light-harvesting complex 2 (LH2). PHOTOSYNTHESIS RESEARCH 2020; 143:115-128. [PMID: 31620983 DOI: 10.1007/s11120-019-00677-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 09/24/2019] [Indexed: 06/10/2023]
Abstract
Enhancing the light-harvesting potential of antenna components in a system of solar energy conversion is an important topic in the field of artificial photosynthesis. We constructed a biohybrid light-harvesting complex 2 (LH2) engineered from Rhodobacter sphaeroides IL106 strain. An artificial fluorophore Alexa Fluor 647 maleimide (A647) was attached to the LH2 bearing cysteine residue at the N-terminal region (LH2-NC) near B800 bacteriochlorophyll a (BChl) assembly. The A647-attached LH2-NC conjugate (LH2-NC-A647) preserved the integrity of the intrinsic chromophores, B800- and B850-BChls, and carotenoids. Femtosecond transient absorption spectroscopy revealed that the sequential energy transfer A647 → B800 → B850 occurs at time scale of 9-10 ps with monoexponential dynamics in micellar and lipid bilayer systems. A B800-removed conjugate (LH2-NC[B800(-)]-A647) exhibited a significant decrease in energy transfer efficiency in the micellar system; however, surprisingly, direct energy transfer from A647 to B850 was observed at a rate comparable to that for LH2-NC-A647. This result implies that the energy transfer pathway is modified after B800 removal. The results obtained suggested that a LH2 complex is a potential platform for construction of biohybrid light-harvesting materials with simple energy transfer dynamics through the site-selective attachment of the external antennae and the modifiable energy-funnelling pathway.
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Affiliation(s)
- Yusuke Yoneda
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - Daiji Kato
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan
| | - Masaharu Kondo
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan
| | - Kenji V P Nagashima
- Research Institute for Integrated Science, Kanagawa University, Kanagawa, 259-1293, Japan
| | - Hiroshi Miyasaka
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531, Japan
| | - Yutaka Nagasawa
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577, Japan.
| | - Takehisa Dewa
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, 466-8555, Japan.
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14
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Saga Y, Yamashita M, Nakagawa S. In situ Conversion of Chlorophyll b Reconstituted into Photosynthetic Protein LH2. CHEM LETT 2019. [DOI: 10.1246/cl.190545] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Madoka Yamashita
- Department of Chemistry, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Shiori Nakagawa
- Department of Chemistry, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
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15
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Selective oxidation of B800 bacteriochlorophyll a in photosynthetic light-harvesting protein LH2. Sci Rep 2019; 9:3636. [PMID: 30842503 PMCID: PMC6403449 DOI: 10.1038/s41598-019-40082-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/04/2019] [Indexed: 11/15/2022] Open
Abstract
Engineering chlorophyll (Chl) pigments that are bound to photosynthetic light-harvesting proteins is one promising strategy to regulate spectral coverage for photon capture and to improve the photosynthetic efficiency of these proteins. Conversion from the bacteriochlorophyll (BChl) skeleton (7,8,17,18-tetrahydroporphyrin) to the Chl skeleton (17,18-dihydroporphyrin) produces the most drastic change of the spectral range of absorption by light-harvesting proteins. We demonstrated in situ selective oxidation of B800 BChl a in light-harvesting protein LH2 from a purple bacterium Rhodoblastus acidophilus by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The newly formed pigment, 3-acetyl Chl a, interacted with the LH2 polypeptides in the same manner as native B800. B850 BChl a was not oxidized in this reaction. CD spectroscopy indicated that the B850 orientation and the content of the α-helices were unchanged by the B800 oxidation. The nonameric circular arrangement of the oxidized LH2 protein was visualized by AFM; its diameter was almost the same as that of native LH2. The in situ oxidation of B800 BChl a in LH2 protein with no structural change will be useful not only for manipulation of the photofunctional properties of photosynthetic pigment-protein complexes but also for understanding the substitution of BChl to Chl pigments in the evolution from bacterial to oxygenic photosynthesis.
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Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1860:209-223. [PMID: 30414933 PMCID: PMC6358721 DOI: 10.1016/j.bbabio.2018.11.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/19/2018] [Accepted: 11/07/2018] [Indexed: 11/22/2022]
Abstract
The light-harvesting 2 complex (LH2) of the purple phototrophic bacterium Rhodobacter sphaeroides is a highly efficient, light-harvesting antenna that allows growth under a wide-range of light intensities. In order to expand the spectral range of this antenna complex, we first used a series of competition assays to measure the capacity of the non-native pigments 3-acetyl chlorophyll (Chl) a, Chl d, Chl f or bacteriochlorophyll (BChl) b to replace native BChl a in the B800 binding site of LH2. We then adjusted the B800 site and systematically assessed the binding of non-native pigments. We find that Arg-10 of the LH2 β polypeptide plays a crucial role in binding specificity, by providing a hydrogen-bond to the 3-acetyl group of native and non-native pigments. Reconstituted LH2 complexes harbouring the series of (B)Chls were examined by transient absorption and steady-state fluorescence spectroscopies. Although slowed 10-fold to ~6 ps, energy transfer from Chl a to B850 BChl a remained highly efficient. We measured faster energy-transfer time constants for Chl d (3.5 ps) and Chl f (2.7 ps), which have red-shifted absorption maxima compared to Chl a. BChl b, red-shifted from the native BChl a, gave extremely rapid (≤0.1 ps) transfer. These results show that modified LH2 complexes, combined with engineered (B)Chl biosynthesis pathways in vivo, have potential for retaining high efficiency whilst acquiring increased spectral range.
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Saga Y, Yamashita M, Imanishi M, Kimura Y. Reconstitution of Chlorophyll d into the Bacterial Photosynthetic Light-harvesting Protein LH2. CHEM LETT 2018. [DOI: 10.1246/cl.180483] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Madoka Yamashita
- Department of Chemistry, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Michie Imanishi
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo 657-8501, Japan
| | - Yukihiro Kimura
- Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo 657-8501, Japan
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Saga Y, Hirota K, Matsui S, Asakawa H, Ishikita H, Saito K. Selective Removal of B800 Bacteriochlorophyll a from Light-Harvesting Complex 2 of the Purple Photosynthetic Bacterium Phaeospirillum molischianum. Biochemistry 2018; 57:3075-3083. [PMID: 29771536 DOI: 10.1021/acs.biochem.8b00259] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The selective removal of B800 bacteriochlorophyll (BChl) a from light-harvesting complex 2 (LH2) in purple photosynthetic bacteria is a clue about elucidation of the mechanism for the transfer of energy from these pigments to B850 BChl a and their roles in the LH2 protein structure. We demonstrated that the kinetics of the removal of B800 BChl a from two representative LH2 proteins derived from Phaeospirillum molischianum and Rhodoblastus acidophilus differed significantly, in contrast to the calculated binding enthalpy. These results may be interpreted as changes in the local structure near B800 BChl a with respect to the geometries of the original crystal structures upon removal of B800 BChl a. Despite the difficulty of removing B800 BChl a from molischianum-LH2, we prepared the molischianum-LH2 protein lacking B800 BChl a by combination of two detergents, n-dodecyl β-d-maltoside and n-octyl β-d-glucoside, under acidic conditions. Spectral and atomic force microscopy analyses indicated that the absence of B800 BChl a had little effect on the local structure in the vicinity of B850 BChl a and the circular arrangement in this protein. These results suggest that the hydrophobic domain near B850 BChl a is rigid and plays a major role in the structural formation of molischianum-LH2.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering , Kindai University , Higashi-Osaka, Osaka 577-8502 , Japan.,Precursory Research for Embryonic Science and Technology , Japan Science and Technology Agency , Kawaguchi , Saitama 332-0012 , Japan
| | - Keiya Hirota
- Department of Chemistry, Faculty of Science and Engineering , Kindai University , Higashi-Osaka, Osaka 577-8502 , Japan
| | - Sayaka Matsui
- Graduate School of Natural Science and Technology , Kanazawa University , Kanazawa 920-1192 , Japan
| | - Hitoshi Asakawa
- Precursory Research for Embryonic Science and Technology , Japan Science and Technology Agency , Kawaguchi , Saitama 332-0012 , Japan.,Graduate School of Natural Science and Technology , Kanazawa University , Kanazawa 920-1192 , Japan.,Bio-AFM Frontier Research Center , Kanazawa University , Kanazawa 920-1192 , Japan
| | - Hiroshi Ishikita
- Department of Applied Chemistry , The University of Tokyo , Bunkyo-ku, Tokyo 113-8654 , Japan.,Research Center for Advanced Science and Technology , The University of Tokyo , Meguro-ku, Tokyo 153-8904 , Japan
| | - Keisuke Saito
- Department of Applied Chemistry , The University of Tokyo , Bunkyo-ku, Tokyo 113-8654 , Japan.,Research Center for Advanced Science and Technology , The University of Tokyo , Meguro-ku, Tokyo 153-8904 , Japan
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Saga Y, Miyagi K. Characterization of 3-Acetyl Chlorophyllaand 3-Acetyl ProtochlorophyllaAccommodated in the B800 Binding Sites of Photosynthetic Light-Harvesting Complex 2 in the Purple Photosynthetic BacteriumRhodoblastus acidophilus. Photochem Photobiol 2018; 94:698-704. [DOI: 10.1111/php.12919] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 03/15/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry; Faculty of Science and Engineering; Kindai University; Higashi-Osaka, Osaka Japan
- Precursory Research for Embryonic Science and Technology; Japan Science and Technology Agency; Kawaguchi Saitama Japan
| | - Kanji Miyagi
- Department of Chemistry; Faculty of Science and Engineering; Kindai University; Higashi-Osaka, Osaka Japan
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Insertion of chlorophyll a derivatives into the binding sites of B800 bacteriochlorophyll a in light-harvesting complex 2 from the purple photosynthetic bacterium Rhodoblastus acidophilus. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.07.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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