Light‐harvesting in <i>Acaryochloris marina</i> – spectroscopic characterization of a chlorophyll <i>d</i>‐dominated photosynthetic antenna system

Schiller, Hilmar; Senger, Horst; Miyashita, Hideaki; Miyachi, Shigetoh; Dau, Holger

doi:10.1016/s0014-5793(97)00620-0

Cited by 61 publications

(28 citation statements)

References 19 publications

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“…1, C and D. The quantum yield of PSII, (23)(24)(25) gave a typical value of ϳ0.7 for F v /F m , which is in agreement with previous reports (20). This is higher than values for other phycobilisome-containing cyanobacteria (see Ref.…”

Section: Methodssupporting

confidence: 91%

“…The room temperature absorption spectrum is characterized by a major peak at ϳ712 nm, consistent with the pigment content of this organism, where Chl d is predominant (1). A second broad peak is seen in the 600 -650 nm range, consistent with the presence of significant amounts of phycobiliproteins, which together with Chl d-binding Pcb proteins, provide a light harvesting system to Acaryochloris (5,20,21). The fluorescence emission spectra show a main peak at 724 nm at room temperature, which is shifted to 732 nm at 77 K. No significant emission from the phycobiliproteins or from detached Pcb proteins is seen, either under the conditions shown (chlorophyll-selected excitation at 470 nm; Fig.…”

Section: Methodsmentioning

confidence: 71%

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The Thermodynamics and Kinetics of Electron Transfer between Cytochrome b6f and Photosystem I in the Chlorophyll d-dominated Cyanobacterium, Acaryochloris marina

Bailleul

Johnson

Finazzi

et al. 2008

Journal of Biological Chemistry

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We have investigated the photosynthetic properties of Acaryochloris marina, a cyanobacterium distinguished by having a high level of chlorophyll d, which has its absorption bands shifted to the red when compared with chlorophyll a. Despite this unusual pigment content, the overall rate and thermodynamics of the photosynthetic electron flow are similar to those of chlorophyll a-containing species. The midpoint potential of both cytochrome f and the primary electron donor of photosystem I (P 740 ) were found to be unchanged with respect to those prevailing in organisms having chlorophyll a, being 345 and 425 mV, respectively. Thus, contrary to previous reports (Hu, Q., Miyashita, H., Iwasaki, I. I., Kurano, N., Miyachi, S., Iwaki, M., and Itoh, S. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 13319 -13323), the midpoint potential of the electron donor P 740 has not been tuned to compensate for the decrease in excitonic energy in A. marina and to maintain the reducing power of photosystem I. We argue that this is a weaker constraint on the engineering of the oxygenic photosynthetic electron transfer chain than preserving the driving force for plastoquinol oxidation by P 740 , via the cytochrome b 6 f complex. We further show that there is no restriction in the diffusion of the soluble electron carrier between cytochrome b 6 f and photosystem I in A. marina, at variance with plants. This difference probably reflects the simplified ultrastructure of the thylakoids of this organism, where no segregation into grana and stroma lamellae is observed. Nevertheless, chlorophyll fluorescence measurements suggest that there is energy transfer between adjacent photosystem II complexes but not from photosystem II to photosystem I, indicating spatial separation between the two photosystems.Acaryochloris marina is an unusual cyanobacterium, because it contains mainly chlorophyll (Chl) 3 d. It was first isolated from a suspension of algae squeezed out of Lissoclinum patella, a colonial ascidian (1). It mainly grows as a biofilm on the undersurface of the ascidian beneath a symbiotic layer of a Prochloron, which is in the upper tunic of the ascidian (2). Other varieties of Acaryochloris have been found on the underside of the thallus of red algae (3) and free living in a salt lake (4). The general feature of its habitat is that it lives at relatively low light intensities, which are enriched in the far red region of the spectrum. Therefore, its oxygenic photosynthesis provides a typical example of adaptation to specific light conditions (2), as evidenced by its pigment composition, where Chl d is predominant and the Chl a level is very low (5, 6). This pigment composition contrasts with the usual high level of Chl a found in other oxygenic phototrophes, as illustrated by the absorption spectrum of a suspension of A. marina cells, which is markedly red-shifted when compared with other Chl a-containing photosynthetic organisms. The extent of the red shift of the absorption spectrum of A. marina is of similar magnitude to that observed b...

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Section: Methodssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 71%

The Thermodynamics and Kinetics of Electron Transfer between Cytochrome b6f and Photosystem I in the Chlorophyll d-dominated Cyanobacterium, Acaryochloris marina

Bailleul

Johnson

Finazzi

et al. 2008

Journal of Biological Chemistry

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“…3% of the Chl d content. [5][6][7] Phycobiliproteins (PBP) are present as antenna in relatively small amounts only. 8,9 Such an unusual pigment composition results in a unique constitution of the photosystems of A. marina.…”

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confidence: 99%

Detection of Chlorophyll d′ and Pheophytin a in a Chlorophyll d-Dominating Oxygenic Photosynthetic Prokaryote Acaryochloris marina

et al. 2001

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Sunlight is the ultimate energy source for the earth, and photosynthesis is essential for maintaining almost all life. The primary process of photosynthesis is initiated by photoexcitation and subsequent charge separation at the socalled reaction center (RC).Oxygenic photosynthetic organisms (higher plants, algae and cyanobacteria) have two types of photosystems (PS), according to the nature of the component molecules of the electron acceptor side. 1,2 One is called PS1, possessing Fe-S centers; another is PS2, having quinones.Chlorophyll (Chl) a (Fig. 1) is an essential pigment for oxygenic photosynthesis. However, charge separation is driven by a few special chlorophyll molecules in each RC of PS1 and PS2. Upon excitation, the primary donor pigments reduce the primary acceptor pigments. The primary donors exhibit sharp absorption changes associated with transient oxidation by flash excitation; they are named P700 in PS1 and P680 in PS2, referring to the characteristic peak wavelengths of the absorbance decrease. The primary donor of PS1 has been speculated to be Chl a′, the 13 2 -epimer of Chl a (Fig. 1); 3 the primary acceptor of PS2 is a metal-free Chl a, namely, Phe a ( Fig. 1). 4 In contrast, both the primary donor of PS2 and the primary acceptor of PS1 are apparently normal-type Chl, namely, Chl a.In 1996, a novel oxygenic alga Acaryochloris marina was isolated from a species of colonial ascidians. 5 Although in all previously known organisms capable of oxygenic photosynthesis the dominating chlorophyll is Chl a, the dominating pigment of A. marina is Chl d (Fig. 1). The Chl a content in A. marina is very low, ca. 3% of the Chl d content. [5][6][7] Phycobiliproteins (PBP) are present as antenna in relatively small amounts only. 8,9 Such an unusual pigment composition results in a unique constitution of the photosystems of A. marina. Because isolated PS1 particles showed a flash-induced absorbance loss maximum at ca. 740 nm, the primary donor of PS1 was named P740, 10 corresponding to P700 in other oxygenic photosynthetic organisms. P740 was assumed to consist of Chl d, and not Chl a′. 10The nature of the primary donor of PS2, P680, is still under debate, because it is hard to detect unambiguously the characteristic spectral signal. In comparison with P700 or P740, the data on P680 still remain scanty. Recently, time-resolved florescence spectroscopy in the ps and ns time range on the A. marina cells showed that a delayed fluorescence peak from PS2 was in the Chl a emission range, and not in the wavelength region of Chl d emission;11 hence, the electron donor of PS2 in A. marina was most probably identical with that of other oxygenic photosynthetic organisms, namely, P680 consisting of Chl a. In contrast, information on the primary electron acceptors of PS1 and PS2 in A. marina is so far quite limited.In this paper, we report on the results of a pigment composition analysis of A. marina cells by silica normal-phase HPLC. Chl d′ and Phe a were detected as minor pigments in

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“…Cells of A. marina grow photoautotrophically (5) and exhibit high oxygen evolving activity even under far-red light of 712 nm (6). The cells contained Chl d and Chl a in a molar ratio of Ϸ30:1, together with a trace amount of phycobilins (4,7), and exhibited component absorption peaks at 694, 714, 726, and 740 nm at 77 K (8). The chemical structure of Chl d, which has a formyl group instead of a vinyl group of Chl a, at C-3 position of the macrocycle chlorin ring (Fig.…”

mentioning

confidence: 99%

A photosystem I reaction center driven by chlorophyll d in oxygenic photosynthesis

Miyashita

Iwasaki

Kurano

et al. 1998

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

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Light‐harvesting in Acaryochloris marina – spectroscopic characterization of a chlorophyll d‐dominated photosynthetic antenna system

Cited by 61 publications

References 19 publications

The Thermodynamics and Kinetics of Electron Transfer between Cytochrome b6f and Photosystem I in the Chlorophyll d-dominated Cyanobacterium, Acaryochloris marina

The Thermodynamics and Kinetics of Electron Transfer between Cytochrome b6f and Photosystem I in the Chlorophyll d-dominated Cyanobacterium, Acaryochloris marina

Detection of Chlorophyll d′ and Pheophytin a in a Chlorophyll d-Dominating Oxygenic Photosynthetic Prokaryote Acaryochloris marina

A photosystem I reaction center driven by chlorophyll d in oxygenic photosynthesis

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