[8] Isolation and functional study of photosystem I subunits in the cyanobacterium Synechocystis sp. PCC 6803

Sun, Jun; Ke, An; Park, Jin; Chitnis, Vaishali P.; Chitnis, Parag R.

doi:10.1016/s0076-6879(98)97010-0

Cited by 48 publications

(35 citation statements)

References 29 publications

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“…Measurement of Photosynthetic Electron Transport Activity-PS I-mediated electron transport rates were measured as oxygen uptake by the Mehler reaction, using 1 mM ascorbate, 2 mM diaminodurene, and 2 mM methyl viologen and a Teflon-coated oxygen electrode (Rank Brothers, UK) (40). Light (intensity of 1,800 mol photons m Ϫ2 s Ϫ1 ) from a halogen lamp was guided via a glass fiber (Moritex, Japan).…”

Section: Methodsmentioning

confidence: 99%

Characterization of Highly Purified Photosystem I Complexes from the Chlorophyll d-dominated Cyanobacterium Acaryochloris marina MBIC 11017

Tomo

Kato

Suzuki

et al. 2008

Journal of Biological Chemistry

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Photochemically active photosystem (PS)IIn addition to P740, the difference spectrum contained an additional band at 728 nm. The redox potentials of P740 were estimated to be 439 mV by spectroelectrochemistry; this value was comparable with the potential of P700 in other cyanobacteria and higher plants. This suggests that the overall energetics of the PS I reaction were adjusted to the electron acceptor side to utilize the lower light energy gained by P740. The distribution of charge in P740 was estimated by a density functional theory calculation, and a partial localization of charge was predicted to P1 Chl (special pair Chl on PsaA). Based on differences in the protein matrix and optical properties of P740, construction of the PS I core in A. marina was discussed.

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Section: Methodsmentioning

confidence: 99%

Characterization of Highly Purified Photosystem I Complexes from the Chlorophyll d-dominated Cyanobacterium Acaryochloris marina MBIC 11017

Tomo

Kato

Suzuki

et al. 2008

Journal of Biological Chemistry

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“…The ratio of chlorophyll to ␤-dodecyl-maltoside was 1:15. The solubilized thylakoid membranes were centrifuged at 15,000 ϫ g for 15 min, and the resulting supernatant was layered on a 10 -30% step gradient of sucrose in 10 mM MOPS, pH 7.0, and 0.05% ␤-dodecyl-maltoside (25). Three distinct bands were resolved after ultracentrifugation at 140,000 ϫ g for 4 h with an angle rotor (70T, Hitachi, Yokohama, Japan).…”

Section: Methodsmentioning

confidence: 99%

PsaK2 Subunit in Photosystem I Is Involved in State Transition under High Light Condition in the Cyanobacterium Synechocystis sp. PCC 6803

Fujimori

Hihara

Sonoike

2005

Journal of Biological Chemistry

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To avoid the photodamage, cyanobacteria regulate the distribution of light energy absorbed by phycobilisome antenna either to photosystem II or to photosystem I (PSI) upon high light acclimation by the process so-called state transition. We found that an alternative PSI subunit, PsaK2 (sll0629 gene product), is involved in this process in the cyanobacterium Synechocystis sp. PCC 6803. An examination of the subunit composition of the purified PSI reaction center complexes revealed that PsaK2 subunit was absent in the PSI complexes under low light condition, but was incorporated into the complexes during acclimation to high light. The growth of the psaK2 mutant on solid medium was inhibited under high light condition. We determined the photosynthetic characteristics of the wild type strain and the two mutants, the psaK1 (ssr0390) mutant and the psaK2 mutant, using pulse amplitude modulation fluorometer. Non-photochemical quenching, which reflects the energy transfer from phycobilisome to PSI in cyanobacteria, was higher in high light grown cells than in low light grown cells, both in the wild type and the psaK1 mutant. However, this change of non-photochemical quenching during acclimation to high light was not observed in the psaK2 mutant. Thus, PsaK2 subunit is involved in the energy transfer from phycobilisome to PSI under high light condition. The role of PsaK2 in state transition under high light condition was also confirmed by chlorophyll fluorescence emission spectra determined at 77 K. The results suggest that PsaK2-dependent state transition is essential for the growth of this cyanobacterium under high light condition.The effective absorption of light energy is the first step in photosynthesis. All oxygenic photosynthetic organisms share common core antenna pigments of ϳ40 chlorophyll a in PSII 1 and ϳ100 chlorophyll a in PSI (1). Cyanobacteria have an additional light-harvesting system, phycobilisome, which is primarily associated with PSII (2, 3). Thus, cyanobacteria use two kinds of antenna pigments with totally different absorption wavelengths.Because neither light quality nor light quantity is constant in natural environments, cyanobacteria have to distribute the light energy absorbed by antenna pigments to two photosystems in order to optimize the photosynthetic performance in response to changing light environments. When cells are exposed to illumination favoring either PSII or PSI, the distribution of light energy between two photosystems would be adjusted (4). When cells have been pre-illuminated with light mainly absorbed by phycobiliproteins (PSII light), the energy transfer to PSI increases, whereas the energy transfer to PSII decreases (state 2). Pre-illumination of cells with light mainly absorbed by chlorophyll a (PSI light) causes a reverse effect leading to the increase of energy transfer to PSII and the decrease of energy transfer to PSI (state 1) (5). Distribution of light energy to two photosystems is regulated in response to the light regime not only in cyanobacteria but also in green ...

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“…PCC 6803 were harvested and suspended in 0.4 M Suc, 10 mM NaCl, 1 mM CaCl 2 , 0.2 mM phenylmethylsulfonyl fluoride, 5 mM benzamidine, and 50 mM MOPS, pH 7.0 (MOPS buffer; Sun et al, 1998). Cells were broken by a bead beater (model 1107900, Biospec Products) for three times of 30 s operation with 2 min intervals.…”

Section: Isolation Of Thylakoid Membranesmentioning

confidence: 99%

The Mutant of sll1961, Which Encodes a Putative Transcriptional Regulator, Has a Defect in Regulation of Photosystem Stoichiometry in the Cyanobacterium Synechocystis sp. PCC 6803

et al. 2005

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In acclimation to changing light environments, photosynthetic organisms modulate the ratio of two photosynthetic reaction centers (photosystem I [PSI] and photosystem II). One mutant, which could not modulate photosystem stoichiometry upon the shift to high light, was isolated from mutants created by random transposon mutagenesis. Measurements of chlorophyll fluorescence and analysis of the reaction center subunits of PSI through western blotting in this mutant revealed that the content of PSI could not be suppressed under high-light condition. In the mutant, transposon was inserted to the sll1961 gene encoding a putative transcriptional regulator. DNA microarray analysis revealed that the expression of sll1773 was drastically induced in the sll1961 mutant upon exposure to high light for 3 h. Our results demonstrate that a transcriptional regulator, Sll1961, and its possible target proteins, including Sll1773, may be responsible for the regulation of photosystem stoichiometry in response to high light.

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[8] Isolation and functional study of photosystem I subunits in the cyanobacterium Synechocystis sp. PCC 6803

Cited by 48 publications

References 29 publications

Characterization of Highly Purified Photosystem I Complexes from the Chlorophyll d-dominated Cyanobacterium Acaryochloris marina MBIC 11017

Characterization of Highly Purified Photosystem I Complexes from the Chlorophyll d-dominated Cyanobacterium Acaryochloris marina MBIC 11017

PsaK2 Subunit in Photosystem I Is Involved in State Transition under High Light Condition in the Cyanobacterium Synechocystis sp. PCC 6803

The Mutant of sll1961, Which Encodes a Putative Transcriptional Regulator, Has a Defect in Regulation of Photosystem Stoichiometry in the Cyanobacterium Synechocystis sp. PCC 6803

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