Isolation and characterization of oxygen-evolving thylakoid membranes and Photosystem II particles from a marine diatom Chaetoceros gracilis

Nagao, Ryo; Ishii, Akiko; Tada, Osamu; Suzuki, Takehiro; Dohmae, Naoshi; Okumura, Akinori; Iwai, Masaru; Takahashi, Takeshi; Kashino, Yasuhiro; Enami, Isao

doi:10.1016/j.bbabio.2007.10.007

Cited by 98 publications

(95 citation statements)

References 38 publications

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“…Preparation of Oxygen-evolving PSII from a Marine Centric Diatom, C. gracilis-A marine centric diatom, C. gracilis, was grown in artificial seawater as described previously (29). Thylakoid membranes and oxygen-evolving PSII were prepared according to Nagao et al (29,30).…”

Section: Methodsmentioning

confidence: 99%

“…Purification Procedures of Five Extrinsic Proteins-The crude PSII suspended in 10 mM MES-NaOH (pH 6.5) (buffer C) was treated with 1 M Tris-HCl (pH 8.5) at 0.5 mg of Chl/ml for 1 h on ice in the dark to release all of the extrinsic proteins of PsbO, PsbQЈ, PsbV, Psb31, and PsbU (29,30,33). The treated samples were centrifuged at 227,000 ϫ g for 30 min after addition of 14% PEG 1450.…”

Section: Methodsmentioning

confidence: 99%

“…The thylakoid membranes were treated with 1% Triton X-100 in buffer A at 1 mg of chlorophyll (Chl)/ml for 5 min at 0°C in the dark and then fractionated by differential centrifugations according to Ref. 29. The resulting oxygen-evolving PSII particles (crude PSII) contained a large amount of fucoxanthin chlorophyll a/c-binding protein and were remarkably unstable as a significant inactivation of oxygen evolution, Chl bleaching and degradation of PSII subunits were observed during incubation at 25°C in the dark (30).…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we succeeded for the first time in preparation of PSII retaining a high oxygen evolving activity from a marine centric diatom, Chaetoceros gracilis (29,30). The diatom PSII was found to contain a novel fifth extrinsic protein (referred to as Psb31 following the nomenclature for PSII subunits (3)) in addition to the four red algal type extrinsic proteins PsbO, PsbQЈ, PsbV, and PsbU (Fig.…”

mentioning

confidence: 99%

“…The diatom PSII was found to contain a novel fifth extrinsic protein (referred to as Psb31 following the nomenclature for PSII subunits (3)) in addition to the four red algal type extrinsic proteins PsbO, PsbQЈ, PsbV, and PsbU (Fig. 1C) (29,30). The gene encoding the novel Psb31 protein was cloned and sequenced (31), which showed that the deduced protein contained three characteristic leader sequences targeted for chloroplast endoplasmic reticulum membrane, chloroplast envelope membrane, and thylakoid membrane, indicating that Psb31 is encoded in the nuclear genome and constitutes one of the extrinsic proteins located on the lumenal side (Fig.…”

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confidence: 99%

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Binding and Functional Properties of Five Extrinsic Proteins in Oxygen-evolving Photosystem II from a Marine Centric Diatom, Chaetoceros gracilis*

Nagao

Moriguchi

Tomo

et al. 2010

Journal of Biological Chemistry

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Oxygen-evolving photosystem II (PSII) isolated from a marine centric diatom, Chaetoceros gracilis, contains a novel extrinsic protein (Psb31) in addition to four red algal type extrinsic proteins of PsbO, PsbQ , PsbV, and PsbU. In this study, the five extrinsic proteins were purified from alkaline Tris extracts of the diatom PSII by anion and cation exchange chromatographic columns at different pH values. Reconstitution experiments in various combinations with the purified extrinsic proteins showed that PsbO, PsbQ , and Psb31 rebound directly to PSII in the absence of other extrinsic proteins, indicating that these extrinsic proteins have their own binding sites in PSII intrinsic proteins. On the other hand, PsbV and PsbU scarcely rebound to PSII alone, and their effective bindings required the presence of all of the other extrinsic proteins. Interestingly, PSII reconstituted with Psb31 alone considerably restored the oxygen evolving activity in the absence of PsbO, indicating that Psb31 serves as a substitute in part for PsbO in supporting oxygen evolution. A significant difference found between PSIIs reconstituted with Psb31 and with PsbO is that the oxygen evolving activity of the former is scarcely stimulated by Cl ؊ and Ca 2؉ ions but that of the latter is largely stimulated by these ions, although rebinding of PsbV and PsbU activated oxygen evolution in the absence of Cl ؊ and Ca 2؉ ions in both the former and latter PSIIs. Based on these results, we proposed a model for the association of the five extrinsic proteins with intrinsic proteins in diatom PSII and compared it with those in PSIIs from the other organisms.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Binding and Functional Properties of Five Extrinsic Proteins in Oxygen-evolving Photosystem II from a Marine Centric Diatom, Chaetoceros gracilis*

Nagao

Moriguchi

Tomo

et al. 2010

Journal of Biological Chemistry

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Functional role of Lys residues of Psb31 in electrostatic interactions with diatom photosystem II

et al. 2017

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We recently revealed that positively charged amino acids of Psb31, an extrinsic subunit found in diatom photosystem II (PSII), are involved in electrostatic interactions with PSII intrinsic subunits. However, the molecular interactions of Psb31 with PSII remain unclear. Here, we report the functional contribution of Lys residues in the binding of Psb31 to PSII using site-directed mutants of Psb31. Each of the K33A, K39A, K54A, K56A, K57A, and K69A mutants exhibits decreased binding affinities to PSII concomitantly with decreases in the O evolution activity. Conversely, each of the K24A, K76A, K80A, and K117A mutants functionally binds to PSII in a manner similar to wild-type Psb31. These results provide evidence that some Lys residues of Psb31 are responsible for electrostatic interactions with PSII.

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Electron Transport between Photosystem II and Photosystem I Encapsulated in Sol–Gel Glasses

2011

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Photosystem I (PSI) and photosystem II (PSII) are the primary solar-energy-converting enzymes of oxygenic photosynthetic organisms. [1] PSI is a robust, potent, and highly efficient photosensitizer capable of providing electrons at a high reduction potential (À0.55 V vs. normal hydrogen electrode, NHE) from its reducing end. [2] These properties have prompted many attempts to integrate PSI into biohybrid systems for solar energy conversion and storage. [3] In a biological setting, water photooxidation by PSII provides a source of electrons for the reductive processes driven by PSI, but in contrast to PSI, integration of PSII into nonbiological systems is very difficult. [4] Both photosystems were successfully "wired" to conductive electrode surfaces, but their integration into a photocatalytic bioelectrochemical device has not been reported to date. [5] Herein we demonstrate a simple scheme for mediated coupling of PSII and PSI in solution; this coupling enables electron flow from water photooxidized by PSII all the way to the reducing end of PSI. Furthermore, we show that the same scheme can be reconstituted either when both photosystems are coencapsulated in sol-gel glasses, or when one photosystem is encapsulated and the other is in solution. The solgel trapping technique is a proven method for encapsulating a wide variety of biological materials, from intact whole cells to functional individual enzymes. [6,7] In addition, sol-gel systems are porous and optically transparent, [8] which makes them ideal scaffolds for photoinduced electron transfer systems such as the photosynthetic machinery. [9] The main difference between the sol-gel and solution samples is that the photosystem complexes are immobilized within the sol-gel cavities instead of diffusing freely in solution. This property suggests interesting possibilities of segregating PSI and PSII in distinct microenvironments while maintaining electron flow between the photosystems. PSII is not naturally directly coupled to PSI (Figure 1, top). Instead, electrons flow from PSII to a pool of membrane-soluble plastoquinones that diffuse between the acceptor and donor sides of PSII, and cytochrome b 6 f (b6f), respectively. [10] Only a fraction of the electrons extracted from water at the oxygen-evolving complex of PSII end up at the acceptor side of PSI. The rest are cycled between PSII and b6f whereby directed diffusion of quinones, the release of protons on the water oxidizing face, and their consumption on the reducing face of the membrane actively pumps protons across the membrane, and generates proton-motive force. [11] By using the amphipathic quinone analogue 2,6dichlorophenolindophenol (DCPIP) as an electron carrier, we were able to bypass b6f and set up an alternative pathway of electron flow from PSII to PSI (Figure 1, bottom). Although it is well established that DCPIP can be reduced by PSII, and the reduced form DCPIPH 2 is an electron donor to PSI, [12] DCPIP-mediated electron flow from PSII to PSI was not reported to date, to the best of our knowl...

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Isolation and characterization of oxygen-evolving thylakoid membranes and Photosystem II particles from a marine diatom Chaetoceros gracilis

Cited by 98 publications

References 38 publications

Binding and Functional Properties of Five Extrinsic Proteins in Oxygen-evolving Photosystem II from a Marine Centric Diatom, Chaetoceros gracilis*

Binding and Functional Properties of Five Extrinsic Proteins in Oxygen-evolving Photosystem II from a Marine Centric Diatom, Chaetoceros gracilis*

Functional role of Lys residues of Psb31 in electrostatic interactions with diatom photosystem II

Electron Transport between Photosystem II and Photosystem I Encapsulated in Sol–Gel Glasses

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