Phycobilisomes of wild type and pigment mutants of the cyanobacterium Synechocystis PCC 6803

Elmorjani, Khalil; Thomas, Jean‐Claude; Sebban, Pierre

doi:10.1007/bf00402349

Cited by 55 publications

(44 citation statements)

References 32 publications

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“…We also present new data on the light transitions in a Synechocystis mutant lacking phycocyanin (Elmorjani et al 1986). In this mutant, state transitions, controlled by the redox state of plastoquinone pool, still occur and can be correlated, as in the wild type, with changes of PS II associated EF particle alignment.…”

Section: Introductionmentioning

confidence: 91%

State 1-state 2 adaptation in the cyanobacteria Synechocystis PCC 6714 wild type and Synechocystis PCC 6803 wild type and phycocyanin-less mutant

Vernotte¹,

Astier²,

Olive

1990

Photosynth Res

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The mechanism of excitation energy distribution between the two photosystems (state transitions) is studied in Synechocystis 6714 wild type and in wild type and a mutant lacking phycocyanin of Synechocystis 6803. (i) Measurements of fluorescence transients and spectra demonstrate that state transitions in these cyanobacteria are controlled by changes in the efficiency of energy transfer from PS II to PS I (spillover) rather than by changes in association of the phycobilisomes to PS II (mobile antenna model). (ii) Ultrastructural study (freeze-fracture) shows that in the mutant the alignment of the PS II associated EF particles is prevalent in state 1 while the conversion to state 2 results in randomization of the EF particle distribution, as already observed in the wild type (Olive et al. 1986). In the mutant, the distance between the EF particle rows is smaller than in the wild type, probably because of the reduced size of the phycobilisomes. Since a parallel increase of spillover is not observed we suggest that the probability of excitation transfer between PS II units and between PS II and PS I depends on the mutual orientation of the photosystems rather than on their distance. (iii) Measurements of the redox state of the plastoquinone pool in state 1 obtained by PS I illumination and in state 2 obtained by various treatments (darkness, anaerobiosis and starvation) show that the plastoquinone pool is oxidized in state 1 and reduced in state 2 except in starved cells where it is still oxidized. In the latter case, no important decrease of ATP was observed. Thus, we propose that in Synechocystis the primary control of the state transitions is the redox state of a component of the cytochrome b 6/f complex rather than that of the plastoquinone pool.

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Section: Introductionmentioning

confidence: 91%

State 1-state 2 adaptation in the cyanobacteria Synechocystis PCC 6714 wild type and Synechocystis PCC 6803 wild type and phycocyanin-less mutant

Vernotte¹,

Astier²,

Olive

1990

Photosynth Res

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“…The phycobilisome of Synechocystis sp. strain PCC6803 consists of a three-cylindrical core from which six rods radiate, each rod being composed of three stacked PC hexamers and three rod linkers (Elmorjani et al, 1986). Most of the rod-subunit-encoding genes are clustered in the cpc operon.…”

Section: Introductionmentioning

confidence: 99%

Phycobilisome rod mutants in Synechocystis sp. strain PCC6803

Ughy

Ajlani

2004

Microbiology

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The phycobilisome is a large pigment-protein assembly that harvests light energy for photosynthesis. This supramolecular complex is composed of two main structures: a core substructure and peripheral rods. Linker polypeptides assemble phycobiliproteins within these structures and optimize light absorption and energy transfer. Mutations have been constructed in three rod-linker-coding genes located in the cpc operon of Synechocystis sp. strain PCC6803. The cpcC1 gene encoding the 33 kDa linker is found to be epistatic to cpcC2 encoding the 30 kDa linker, indicating a specific role for each of these two linkers in rod growth. This corroborates studies on the sequential degradation of phycobilisomes upon nitrogen starvation. Three allelic mutants affecting cpcC2 revealed a polar effect of commonly used cassettes (aphI, aadA) on the operon steady-state transcripts and an effect of rod linker availability on the amount of phycocyanin incorporated in the phycobilisome. This led to the proposal that regulation of rod length could occur through processing of transcripts upstream of the cpcC2 gene.

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“…The data indicate that energy transfer in the phycobilisome from phycocyanin to allophycocyanin is apparently normal in the PSII-cells: excitation with light specific for phycocyanin yields a fluorescence maximum at 668 nm for the mutant and wild-type samples. If phycobilisomes were dissociated, energy transfer between phycocyanin and allophycocyanin would be disrupted and phycocyanin fluorescence at 648 nm would appear (9); no appreciable increases in fluorescence are seen at this wavelength. In addition to the peak at 668 nm (phycobilisomes), fluorescence emission maxima near 695 nm and at 725 nm are also seen in cells illuminated with light of 580 nm (Fig.…”

Section: Characterization Of Phycobiliproteins and Phycobilisomesmentioning

confidence: 99%

Spectral Properties and Composition of Reaction Center and Ancillary Polypeptide Complexes of Photosystem II Deficient Mutants of Synechocystis 6803

Dzelzkalns¹,

Bogorad²

1989

Plant Physiol.

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The polypeptide composition and spectral properties of three photosystem 11 (PSII) deficient mutants of the cyanobacterium Synechocystis 6803 have been determined. The levels of the 43 and 47 kilodalton chlorophyll-binding proteins and the reaction center component D2 are affected differently in each mutant; the 33 kD polypeptide of the oxygen-evolving complex is found at wild-type levels in all three. The 43 and 47 kilodalton proteins are implicated as important elements in the assembly and/or stability of the PSII reaction center, although the loss of one of these polypeptides does not lead to the loss of all PSII proteins. Low temperature fluorescence emission spectra of wild-type cells reveal chlorophyll-attributable peaks at 687 (PSII), 696 (PSII), and 725 (photosystem 1) nanometers. All three mutants retain the 725 nanometer fluorescence but lack the 696 nanometer peak. This suggests that the latter fluorescence arises from PSII reaction center chlorophyll or results from interactions among functional PSII components in vivo. Cells that contain the 43 kilodalton and lack the 47 kilodalton protein, retain the 687 fluorescence; furthermore, in as much as this fluorescence is absent from cells without the 43 kilodalton protein, the 687 nanometer peak is judged to emanate from the 43 kilodalton chlorophyll-protein. A new peak, probably previously obscured, is revealed at 691 nanometers in cells that retain the 47 kilodalton protein but lack the 43 kilodalton polypeptide, suggesting that emission near 691 nanometers can be attributed to the 47 kilodalton polypeptide. Membrane-bound phycobilisomes are retained in these cells as is coupled-energy transfer between phycocyanin and allophycocyanin. Energy transfer to photosystem I by way of phycocyanin excitation proceeds as in wild-type cells despite the absence of certain PSII components.Light energy absorbed by the accessory pigments associated with PSII is transferred to the PSII reaction center leading to charge separation and the release of molecular oxygen. These processes-light absorption, charge separation, and oxygen evolution-occur in three spatially distinct but functionally interdependent complexes. In cyanobacteria, light is gathered principally by phycobilisomes, well-studied supramolecular complexes composed of repeated units of several chromophore-conjugated phycobiliproteins and 'colorless' polypeptides (3,30 (15,20,26, and see below), however, little evidence has been obtained for the existence of counterparts to the chloroplast 16 and 23 kD proteins (26).Two major Chl-fluorescence emission maxima seen at 77 K have been associated with PSII preparations of chloroplasts (4,22). A peak at 685 nm (F685) has alternatively been identified with a fluorescence emission peak exhibited by the isolated 43 kD Chl-binding protein (17) and, more recently, it has been attributed to the back reaction of P680+ and pheophytin-(1, 24). A second maximum at 695 nm (F695) has been ascribed to the 47 kD Chl-containing protein (5,17,22,23,29), as well as to pheo...

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Phycobilisomes of wild type and pigment mutants of the cyanobacterium Synechocystis PCC 6803

Cited by 55 publications

References 32 publications

State 1-state 2 adaptation in the cyanobacteria Synechocystis PCC 6714 wild type and Synechocystis PCC 6803 wild type and phycocyanin-less mutant

State 1-state 2 adaptation in the cyanobacteria Synechocystis PCC 6714 wild type and Synechocystis PCC 6803 wild type and phycocyanin-less mutant

Phycobilisome rod mutants in Synechocystis sp. strain PCC6803

Spectral Properties and Composition of Reaction Center and Ancillary Polypeptide Complexes of Photosystem II Deficient Mutants of Synechocystis 6803

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