What is β–carotene doing in the photosystem II reaction centre?

Telfer, Alison

doi:10.1098/rstb.2002.1139

Cited by 204 publications

(161 citation statements)

References 74 publications

Supporting

Mentioning

154

Contrasting

Unclassified

Order By: Relevance

“…Thus, our in vivo data suggest that PSII undergoes a transition from an unquenched to a weakly quenched state and then a strongly quenched state during photoinactivation, as has been proposed (16). The weaker quencher with a fluorescence lifetime centered at 1.25 ns may be related to mechanisms such as quenching by Chl ϩ or P680 ϩ (43) or cyclic electron transfer within PSII involving cytochrome b 559 (or Chl z ), ␤-carotene, and P680 (44)(45)(46), which could specifically quench F m but may have a limited capacity to prevent further photooxidative damage (47). When the situation deteriorates with greater light dosage, and more than half of PSII centers have been photoinactivated, modification of PSII component(s) could also enhance quencher formation (20,48), which may then give rise to the stronger quencher at 0.58 ns.…”

Section: Formation Of Weak and Then Strong Quenchers Of Excitation Enmentioning

confidence: 93%

Populations of photoinactivated photosystem II reaction centers characterized by chlorophyllafluorescence lifetimein vivo

Matsubara

Chow

2004

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

124

111

View full text Add to dashboard Cite

O xygenic photosynthetic organisms grow under an everchanging sunlight environment. Fluctuations of solar energy input can be accommodated by a tradeoff between energy utilization in photosynthetic carbon assimilation and energy dissipation by various photoprotective mechanisms that modulate absorption and dissipation of excess light energy (1-3). Despite the complex suite of strategies for photoprotection, however, photooxidative damage inevitably occurs to photosystem (PS) II, in which P680 ϩ (a special Chl in the PSII reaction center), the strongest biological oxidant, is generated to split water to molecular oxygen, protons, and electrons (4). The consequent loss of PSII photochemical efficiency measured under low light, termed photoinhibition or photoinactivation (5), depends inter alia on the number of absorbed photons during the light exposure (6-8). That is, PSII photoinactivation can occur with a light-dosage-dependent probability under any light environment in nature, ranging from limiting to saturating irradiances. Over a sunny day, the entire population of PSII in a leaf may undergo photoinactivation.Yet, effects of photoinactivation on PSII efficiency are not always obvious; they are noticeable only when the rate of inactivation exceeds the capacity for rapid and efficient repair of nonfunctional PSII reaction centers by de novo synthesis of D1 protein (psbA gene product in PSII reaction center) (9). The operation of the PSII repair cycle involves coordinated regulation of degradation and synthesis of D1 protein (10). When the supply of newly synthesized D1 protein is insufficient, such as under high light and͞or low temperature, the degradation process also slows down (11,12), resulting in the accumulation of nonfunctional PSII reaction centers in stacked grana domains of the thylakoid membranes of higher plants (13). These nonfunctional PSII centers, capable of light absorption but not of photosynthetic electron transfer, reduce the PSII quantum efficiency of leaves or leaf segments.An important implication of PSII photoinactivation is that nonfunctional PSII centers, still embracing pigment molecules, can exacerbate photooxidative damage to the thylakoid membranes unless light energy absorbed by the pigments is dissipated safely. Thus, it has been hypothesized that photoinactivated PSII complexes are able to efficiently dissipate excitation energy harmlessly (14), and further, may contribute to photoprotection of their functional neighbors by acting as sinks for excitation energy (13,15).Experimental results consistent with this hypothesis have emerged from recent studies using leaves of Capsicum annuum L (16, 17). In leaves of C. annuum in the presence of lincomycin (an inhibitor of chloroplast-encoded protein synthesis), the functional fraction of PSII ( f ), determined from the oxygen yield per single-turnover flash or from chlorophyll (Chl) a fluorescence, decreased monoexponentially from 1.0 (ϭ the original level) to Ϸ0.3 under illumination (16). However, the decrease in f thereafter proceed...

show abstract

Section: Formation Of Weak and Then Strong Quenchers Of Excitation Enmentioning

confidence: 93%

Populations of photoinactivated photosystem II reaction centers characterized by chlorophyllafluorescence lifetimein vivo

Matsubara

Chow

2004

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

124

111

View full text Add to dashboard Cite

show abstract

“…Each oxidation state generated in the oxygen-evolving centre (OEC) is represented as an intermediate of the S-state cycle ( Joliot et al 1969;Kok et al 1970) of which there are five distinct states (S0-S4). In addition to these reactions, side reactions can occur under some conditions including the oxidation of a high-potential cytochrome bound within the PSII core complex (Cyt b559), a b-carotene molecule and a Chl a molecule (Chl Z ; Stewart & Brudvig 1998;Faller et al 2001;Telfer 2002;Tracewell & Brudvig 2003). These side reactions occur on the tens of millisecond time scale and therefore do not compete with the electron transfer pathway leading to water oxidation.…”

Section: The Reactions Of Psiimentioning

confidence: 99%

Photosynthetic generation of oxygen

Barber

2008

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

The oxygen in the atmosphere is derived from light-driven oxidation of water at a catalytic centre contained within a multi-subunit enzyme known as photosystem II (PSII). PSII is located in the photosynthetic membranes of plants, algae and cyanobacteria and its oxygen-evolving centre (OEC) consists of four manganese ions and a calcium ion surrounded by a highly conserved protein environment. Recently, the structure of PSII was elucidated by X-ray crystallography thus revealing details of the molecular architecture of the OEC. This structural information, coupled with an extensive knowledge base derived from a wide range of biophysical, biochemical and molecular biological studies, has provided a framework for understanding the chemistry of photosynthetic oxygen generation as well as opening up debate about its evolutionary origin.

show abstract

“…Oxidation of carotenoids by singlet oxygen is an unavoidable consequence of oxygenic photosynthesis. This oxidation is especially true of β-carotene, which is the only carotenoid found in the core of PSII, the site of the water-splitting/oxygen-evolving complex (10,38). The main role of β-carotene in the reaction center is quenching of singlet oxygen (10,11,39).…”

Section: Discussionmentioning

confidence: 99%

“…This oxidation is especially true of β-carotene, which is the only carotenoid found in the core of PSII, the site of the water-splitting/oxygen-evolving complex (10,38). The main role of β-carotene in the reaction center is quenching of singlet oxygen (10,11,39). Bleaching of this β-carotene by singlet oxygen has been proposed to trigger turnover of the D1 protein in the PSII reaction center (40).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Lycopene cyclase paralog CruP protects against reactive oxygen species in oxygenic photosynthetic organisms

Bradbury

Shumskaya

Tzfadia

et al. 2012

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

View full text Add to dashboard Cite

In photosynthetic organisms, carotenoids serve essential roles in photosynthesis and photoprotection. A previous report designated CruP as a secondary lycopene cyclase involved in carotenoid biosynthesis [Maresca J, et al. (2007) Proc Natl Acad Sci USA 104:11784-11789]. However, we found that cruP KO or cruP overexpression plants do not exhibit correspondingly reduced or increased production of cyclized carotenoids, which would be expected if CruP was a lycopene cyclase. Instead, we show that CruP aids in preventing accumulation of reactive oxygen species (ROS), thereby reducing accumulation of β-carotene-5,6-epoxide, a ROS-catalyzed autoxidation product, and inhibiting accumulation of anthocyanins, which are known chemical indicators of ROS. Plants with a nonfunctional cruP accumulate substantially higher levels of ROS and β-carotene-5,6-epoxide in green tissues. Plants overexpressing cruP show reduced levels of ROS, β-carotene-5,6-epoxide, and anthocyanins. The observed up-regulation of cruP transcripts under photoinhibitory and lipid peroxidation-inducing conditions, such as high light stress, cold stress, anoxia, and low levels of CO 2 , fits with a role for CruP in mitigating the effects of ROS. Phylogenetic distribution of CruP in prokaryotes showed that the gene is only present in cyanobacteria that live in habitats characterized by large variation in temperature and inorganic carbon availability. Therefore, CruP represents a unique target for developing resilient plants and algae needed to supply food and biofuels in the face of global climate change.photoinhibition | stress tolerance | chilling stress | oxygenic photosynthesis

show abstract

What is β–carotene doing in the photosystem II reaction centre?

Cited by 204 publications

References 74 publications

Populations of photoinactivated photosystem II reaction centers characterized by chlorophyllafluorescence lifetimein vivo

Populations of photoinactivated photosystem II reaction centers characterized by chlorophyllafluorescence lifetimein vivo

Photosynthetic generation of oxygen

Lycopene cyclase paralog CruP protects against reactive oxygen species in oxygenic photosynthetic organisms

Contact Info

Product

Resources

About