Mechanism of the Down Regulation of Photosynthesis by Blue Light in the Cyanobacterium <i>Synechocystis</i> sp. PCC 6803

Scott, Matt; Mccollum, Chantal; Васильев, С. В.; Crozier, Cheryl; Espie, George S.; Król, Marianna; Hüner, N. P. A.; Bruce, Doug

doi:10.1021/bi060767p

Cited by 85 publications

(60 citation statements)

References 31 publications

(47 reference statements)

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“…Following induction of NPQ, the quenching could be sustained in the dark by the addition of 3% (v/v) of a protein cross-linker, glutaraldehyde, 10 s prior to removing the actinic illumination. A similar technique has previously been used to sustain NPQ present in cyanobacteria (31). The absence of NPQ relaxation was confirmed by application of saturating light pulses (Fig.…”

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confidence: 65%

Photoprotective Energy Dissipation in Higher Plants Involves Alteration of the Excited State Energy of the Emitting Chlorophyll(s) in the Light Harvesting Antenna II (LHCII)

Johnson

Ruban

2009

Journal of Biological Chemistry

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The photosynthetic apparatus of plants and algae has evolved a process of feedback control of energy input into the photosynthetic reaction centers, revealed in observations of the nonphotochemical quenching of chlorophyll fluorescence (NPQ) 2 (1-3). Exposure to high light intensity leads to closure of a large fraction of photosystem II (PSII) reaction centers and the buildup of the proton gradient across the photosynthetic membrane (⌬pH). The latter prompts the transition of the PSII light harvesting antenna (LHCII) into the photoprotective state (4 -6), where a large proportion of the absorbed energy is rapidly converted into heat, preventing photoinhibitory damage of reaction centers. The molecular mechanism of NPQ is currently under scrupulous multidisciplinary investigation (7-14).Many of these studies have centered on the search for pigments associated with light harvesting complexes that may act as energy traps/quenchers. In recent years certain evidence has accumulated that xanthophylls may play a central role in photoprotective energy dissipation. A carotenoid radical cation, suggested to be zeaxanthin, was found to correlate with the level of NPQ and was proposed to act as a direct quencher of chlorophyll excitation (7, 10). Other studies indicated the involvement of energy transfer to the S 1 state of LHCII-bound lutein 1 (9, 15). Evidence of these putative quenchers occurring in vivo was provided (7, 9), yet little is known about how ⌬pH activates them. ⌬pH is believed to protonate luminal residues on the PSII subunit PsbS and LHC complexes causing certain conformational changes to occur, which are necessary for NPQ (5, 6). These conformational changes are not well understood but can be traced by changes in LHCII-bound pigments detected by absorption and resonance Raman spectroscopy (9,(15)(16)(17)(18)(19)(20).Both the proposed zeaxanthin-and lutein-quenching mechanisms assume very close (van der Waals) contact between the quenching xanthophyll and chlorophyll. Such an interaction would, most likely, affect the energy levels of the pigments involved, which may be required to convert the xanthophyll into an energy quencher. Indeed, a subpopulation of zeaxanthin molecules in PSII was reported to undergo an absorption redshift in the NPQ state (18 -20). Recently, lutein absorption was also found to be decreased in the dissipative state (20), interestingly this loss of molar extinction was enhanced by the presence of zeaxanthin.Whereas many studies have probed the role of xanthophylls, relatively little is known about the state of chlorophylls upon formation of NPQ. Some research suggests that chlorophyll associates may be formed in the NPQ state, which potentially could act as quenchers (21-23). It has been proposed that such associates have red-shifted absorption and fluorescence spectra. Low temperature (77K) fluorescence spectra of quenched LHCII aggregates possess a 20-nm red-shifted band, F700 (22), which was also detected in leaves and thylakoids frozen in the NPQ state (21, 24). The F700 emitting...

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confidence: 65%

Photoprotective Energy Dissipation in Higher Plants Involves Alteration of the Excited State Energy of the Emitting Chlorophyll(s) in the Light Harvesting Antenna II (LHCII)

Johnson

Ruban

2009

Journal of Biological Chemistry

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“…In contrast, the mechanism of thermal energy dissipation in cyanobacteria, which plays a key role in global carbon cycling, remained elusive. Only within the last few years has a photoprotective mechanism associated with the soluble phycobilisome antenna of PSII in cyanobacteria been demonstrated (8)(9)(10)(11)(12)(13)(14). A specific soluble carotenoid protein, the orange carotenoid protein (OCP), plays an essential role in this process (9,10).…”

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confidence: 99%

“…Surprisingly, the role of the carotenoid in the OCP is completely different from the role of the photoprotective carotenoids in plants. The OCP appears to act as a photoreceptor, responding to blue-green light; this induces energy dissipation, resulting in a detectable quenching of the cellular fluorescence, known as nonphotochemical-quenching (NPQ), through interaction with the phycobilisome (9,11). In mutants containing the OCP but lacking phycobilisomes, blue-green light was unable to induce the photoprotective mechanism (9,10).…”

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A photoactive carotenoid protein acting as light intensity sensor

Wilson

Punginelli

Gall

et al. 2008

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

321

431

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Intense sunlight is dangerous for photosynthetic organisms. Cyanobacteria, like plants, protect themselves from light-induced stress by dissipating excess absorbed energy as heat. Recently, it was discovered that a soluble orange carotenoid protein, the OCP, is essential for this photoprotective mechanism. Here we show that the OCP is also a member of the family of photoactive proteins; it is a unique example of a photoactive protein containing a carotenoid as the photoresponsive chromophore. Upon illumination with blue-green light, the OCP undergoes a reversible transformation from its dark stable orange form to a red ''active'' form. The red form is essential for the induction of the photoprotective mechanism. The illumination induces structural changes affecting both the carotenoid and the protein. Thus, the OCP is a photoactive protein that senses light intensity and triggers photoprotection.cyanobacteria ͉ nonphotochemical quenching ͉ photoprotection ͉ phycobilisome

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“…It has been recently shown that, in cyanobacteria, like in plants, there exists a photoprotective process that decreases the energy transfer between the antenna and the reaction centers by increasing thermal dissipation (8)(9)(10)(11)(12)(13). However, this mechanism is not triggered by a lowering of the luminal pH, as occurs in plants;…”

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Identification of a protein required for recovery of full antenna capacity in OCP-related photoprotective mechanism in cyanobacteria

Boulay

Wilson

D’Haene

et al. 2010

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

131

110

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High light can be lethal for photosynthetic organisms. Similar to plants, most cyanobacteria protect themselves from high irradiance by increasing thermal dissipation of excess absorbed energy. The photoactive soluble orange carotenoid protein (OCP) is essential for the triggering of this photoprotective mechanism. Light induces structural changes in the carotenoid and the protein, leading to the formation of a red active form. Through targeted gene interruption we have now identified a protein that mediates the recovery of the full antenna capacity when irradiance decreases. In Synechocystis PCC 6803, this protein, which we called the fluorescence recovery protein (FRP), is encoded by the slr1964 gene. Homologues of this gene are present in all of the OCP-containing strains. The FRP is a 14-kDa protein, strongly attached to the membrane, which interacts with the active red form of the OCP. In vitro this interaction greatly accelerates the conversion of the red OCP form to the orange form. We propose that in vivo, FRP plays a key role in removing the red OCP from the phycobilisome and in the conversion of the free red OCP to the orange inactive form. The discovery of FRP and its characterization are essential elements in the understanding of the OCPrelated photoprotective mechanism in cyanobacteria.carotenoid | nonphotochemical quenching | phycobilisome | photoreceptor | Synechocystis B ecause too much light can be lethal for photosynthetic organisms, photoprotection against excess absorbed light energy is an essential and universal attribute of oxygenic photosynthetic organisms. Survival, productivity, and habitat preference are largely determined by development of photoprotective mechanisms. One of these mechanisms, which is induced by high irradiance, dissipates the excess harmful absorbed energy into heat at the levels of the antennae.In all photosynthetic organisms, the function of the light harvesting antenna is similar: to collect and concentrate light energy in the photochemical reaction centers in which light energy is converted into chemical energy. In plants and green algae, light is principally harvested by membrane-embedded complexes noncovalently binding chlorophyll and carotenoid molecules. These complexes show a large structural and functional flexibility. They are reversibly switched from a very efficient energy collecting state into a photoprotected state. This state allows the conversion of excess energy into heat, decreasing the energy arriving at the reaction centers under high light conditions (1-4). Cyanobacteria are oxygenic photosynthetic prokaryotes that play a key role in global carbon cycling. To harvest light. most cyanobacteria use a large, membrane-extrinsic complex called the phycobilisome (PB), which is composed of several types of chromophorylated phycobiliproteins and of linker peptides (for reviews, see refs. 5-7).It has been recently shown that, in cyanobacteria, like in plants, there exists a photoprotective process that decreases the energy transfer between the antenna and ...

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Mechanism of the Down Regulation of Photosynthesis by Blue Light in the Cyanobacterium Synechocystis sp. PCC 6803

Cited by 85 publications

References 31 publications

Photoprotective Energy Dissipation in Higher Plants Involves Alteration of the Excited State Energy of the Emitting Chlorophyll(s) in the Light Harvesting Antenna II (LHCII)

Photoprotective Energy Dissipation in Higher Plants Involves Alteration of the Excited State Energy of the Emitting Chlorophyll(s) in the Light Harvesting Antenna II (LHCII)

A photoactive carotenoid protein acting as light intensity sensor

Identification of a protein required for recovery of full antenna capacity in OCP-related photoprotective mechanism in cyanobacteria

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