CHARACTERIZATION OF PIGMENT MUTANTS IN A BLUEGREEN ALGA, <i>ANACYSTIS NIDULANS</i><sup>1</sup>

Stevens, C. L. R.; Myers, Jack

doi:10.1111/j.1529-8817.1976.tb02834.x

Cited by 34 publications

(15 citation statements)

References 25 publications

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“…The ratio of RC II to phycobilisomes is determined to be 4.1 ± 1.3 for Neoagardhiella and 1.7 ± 0.5 for Anacystis (Table III). The RC II/phycobilisome ratio for Neoagardhiella is in good agreement with a value of 3 to 4 EF particles (putative RC II)/phycobilisome found for the red alga Grifflthsia pacflcia (23) and that for Anacystis is similar to an estimate of 1.1 RC II/phycobilisome (24).…”

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confidence: 73%

Photosynthetic Unit Organization in a Red Alga

Kursar¹,

Alberte²

1983

Plant Physiol.

136

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The relative concentration of biliproteins, phycobilisomes, chlorophyll a, and reaction centers I and II are reported for Neoagardhiella bailyei, a macrophytic red alga collected in the field and compared with Anacystis ridudas, a cyanobacterium cultured in the laboratory. The ratios of chlorophyll to reaction center I, of chlorophyll to reaction center II, and the mass of phycobiliprotein per reaction center II are quite similar in Neoagardella and Anacystis, supporting the concept that the red algal chloroplast is derived from a cyanobacterial progenitor. The ratios of reaction center I to reaction center II are about 2.3 in both species. The Anacystis phycobilisome has about 40% of the mass of the Neoagardhella phycobilisome, 4.9 and 14.9 x 10 daltons, respectively. The reaction center II/ phycobilisome ratio is about 1.7 in Anacystis and 4.1 in Neoagardhiell Phycobilisome size and physical restrictions on phycobilisome packing may be a major constraint on the reaction center II-phycobilisome association and the assembly of the photosynthetic membrane in both the red algae and cyanobacteria.Essentially all of the photosynthetically active pigments are bound to proteins. The sole function of greater than 99% of these pigment-proteins is to harvest light for photosynthesis. For example, in the cyanobacterium Anacystis nidulans, a photon absorbed by its major light-harvesting complex, C-phycocyanin (X..x 620 nm), leads to an excited state of this pigment. The excitation then migrates to allophycocyanin (X,,, 650 nm) and finally to Chl a and the long wavelength photochemical traps. In macrophytic red algae, which are characterized by the red pigment R-phycoerythrin (maxima at 498, 545, and 565 nm), light absorbed by this pigment-protein is transferred to phycocyanin and follows the same path as described for Anacystis (7). Therefore, efficient light harvesting and energy transfer in these algae require that the pigment-proteins form aggregates which are closely associated with each other and with the traps. Consequently, phycobiliproteins ofthe cyanobacteria and red algae are organized into discrete structures, phycobilisomes, which are attached to the photosynthetic lamellae.The structure of the photosynthetic apparatus can most easily be studied in the red algae and cyanobacteria inasmuch as (a) the

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supporting

confidence: 73%

Photosynthetic Unit Organization in a Red Alga

Kursar¹,

Alberte²

1983

Plant Physiol.

136

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“…In PBsome-containing organisms it is generally assumed that the arrangement of the photosystems in the thylakoid is predictable from the PSII/phycobiliprotein ratio (6,7) and that the PBsome distribution on the stromal surface is indicative of the PSII location (8,9). Since PBsomes with PSII activity have been isolated, a direct functional association exists in vivo (10), although a direct interaction between PBsomes and PSI cannot be ruled out.…”

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confidence: 99%

Photosynthetic membrane topography: quantitative in situ localization of photosystems I and II.

Mustárdy

Cunningham

Gantt

1992

Proc. Natl. Acad. Sci. U.S.A.

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Photosynthesis is a biological process whose efficiency depends on the coordinated interaction of several participating protein complexes that reside in the photosynthetic membrane. Our understanding of the photosynthetic membrane structure is largely derived from studies on fractionated membranes and from conventional electron microscopy (1, 2), and our knowledge of the spatial and functional interaction between principal membrane complexes is quite limited. Such information is directly relevant to excitation energy transfer as well as to the diffusion of mobile electron carriers (3, 4) in photosynthetic membranes of oxygen-evolving plants. Major integral protein complexes include ATP synthase, cytochrome b6/f, photosystem I (PSI), and photosystem II (PSII) and LHCII in green plants. In phycobilisome (PBsome)-containing organisms-namely, red algae and cyanobacteria-the LHCII complex appears to be absent and PBsomes on the stromal surface serve as the principal light-harvesting antennae (5). In PBsome-containing organisms it is generally assumed that the arrangement of the photosystems in the thylakoid is predictable from the PSII/phycobiliprotein ratio (6, 7) and that the PBsome distribution on the stromal surface is indicative of the PSII location (8, 9). Since PBsomes with PSII activity have been isolated, a direct functional association exists in vivo (10), although a direct interaction between PBsomes and PSI cannot be ruled out. The following questions are being addressed here: (i) how many PSI and PSII centers exist per unit of surface area, (ii) is the distribution of PSI and PSII uniform throughout the membrane, (iii) are the photosystems present as monomers or as clusters, and (iv) if they are clustered, does the cluster size change under different growth conditions?By conventional immunocytochemical methods, the subcellular distribution of proteins in plants is well established, including specific localization of a number of chloroplast components in land plants and algae (1,11,12). We have shown that this approach can be used to provide a quantitative measure of the relative amounts of PSI and PSII in Porphyridium cruentum (13,14). However, since antigenic sites are accessible only on exposed surfaces of embedded sections, the absolute number of particular components is greatly underestimated, and spatial distances between individual complexes are difficult to ascertain.To ascertain the spatial relationships of PSI and PSII requires intact membranes and a means of identifying the photosystems. By freeze-fracture, 10-nm particles exposed on the exoplasmic fracture face are regarded as representing PSII centers. The isolation of PSII particles and their visualization in lipid vesicles support this attribution (15). Also, there is good evidence that some 10-to 13-nm particles on the protoplasmic fracture face represent PSI (2), but one cannot identify individual particles as photosystems. Since PSI and PSII particles are not identifiable in the same fracture-face, meaningful spatial correlations...

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“…The quantitative relationships between PSII and the PBsomes are still not clear. For example, recent quantitative studies of the RC and pigment content of red algae and cyanobacteria (10,25,28) have shown that the RCII:PBsome ratio is variable and can often be greater than unity. Furthermore, Diner (1) Woilman (29) have presented evidence that in the red alga Cyanidium caldarium about half of the RCII do not receive any of the light energy absorbed by the PBsomes.…”

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Effective Absorption Cross-Sections in Porphyridium cruentum

Ley

1984

Plant Physiol.

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ABSTRACIEffective absorption cross-sections for 02 production by Porphyridium cruentum were measured at 546 and 596 nanometers. Although all photosystem II reaction centers are energetically coupled to phycobilisomes, any single phycobilisome acts as antenna for several photosystem II reaction centers. The cross-section measured in state I was 50% larger than that measured in state II.The phycobiliproteins are major light-harvesting components in the photosynthetic apparatus of the red algae and cyanobacteria (9). In these organisms, the phycobiliproteins are contained in large, highly organized, multi-protein aggregates called PBsomes2 which are located on the external surface of the photosynthetic membrane (4). Despite their extralamellar location, the PBsomes transfer absorbed light energy with high specificity and efficiency to PSII which is located within the membrane (11,12 pellet was resuspended in fresh growth medium at an equivalent Chl concentration of 10 to 20 ,M. We calculate that, after settling on the electrode surface, the cells covered less than 30% of the floor area of our 02 polarograph (14).To measure effective absorption cross-sections in P. cruentum, I used a modification of our previously published method (14). I simultaneously illuminated cells resting on the surface of the bare platinum electrode with two sources of light. The first was a continuous green (541 nm) or blue (446 nm) background light. The second was a train (0.2 Hz) of laser flashes. To establish state II or state I, the cells were preilluminated for 5 min with bright green (100 x 1014 quanta cm-2 s-') or bright blue (61 x 1014 quanta cm-2 s-1) continuous light, respectively. These bright irradiances are at the upper end of the range of irradiances used in previous studies to produce state transitions (13,19,22,24). Preillumination ofthe algae with bright light gave the most stable and reproducible rates of 02 evolution in subsequent dim illuminations. The bright green and bright blue illuminations produced rates of 02 production that were 89% and 28%, respectively, of the light-saturated rate. For the cross-section measurements, we then reduced background irradiances to 1.0 x 10'4 quanta cm 2 s51 (green) or 1.7 x 10'4 quanta cm -2 S-' (blue). The dim 541 and 446 nm illuminations supported rates of 02 production that were 6% and 3% of the light-saturated rate, respectively, and both allowed maximum 02 flash yields. 02 flash yields and rates of 02 production reached their low-light steady state values within 2 min after the change from high to low continuous blue irradiance and in 3 to 4 min following the change from high to low continuous green irradiance. We began our cross-section measuremnts, which took a total of 8 to 12 min to complete, as soon as steady state 02 flash yields had been established.I generated 546 and 596 nm laser flashes of 0.5 As total duration using methanolic solutions of 100 ,M Coumarin 540 or 50 ,M Rhodamine 590 (Exciton, Dayton, OH), respectively, in a flashlamp-pumped dye laser (DL21OOC, Phasar Co...

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CHARACTERIZATION OF PIGMENT MUTANTS IN A BLUEGREEN ALGA, ANACYSTIS NIDULANS¹

Cited by 34 publications

References 25 publications

Photosynthetic Unit Organization in a Red Alga

Photosynthetic Unit Organization in a Red Alga

Photosynthetic membrane topography: quantitative in situ localization of photosystems I and II.

Effective Absorption Cross-Sections in Porphyridium cruentum

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CHARACTERIZATION OF PIGMENT MUTANTS IN A BLUEGREEN ALGA, ANACYSTIS NIDULANS1

Cited by 34 publications

References 25 publications

Photosynthetic Unit Organization in a Red Alga

Photosynthetic Unit Organization in a Red Alga

Photosynthetic membrane topography: quantitative in situ localization of photosystems I and II.

Effective Absorption Cross-Sections in Porphyridium cruentum

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CHARACTERIZATION OF PIGMENT MUTANTS IN A BLUEGREEN ALGA, ANACYSTIS NIDULANS¹