Phosphorylation of LHCII at Low Temperatures

Bingsmark, Sophie; Larsson, Ulla K.; Andersson, Bertil

doi:10.1007/978-94-009-0511-5_402

Cited by 3 publications

(3 citation statements)

References 3 publications

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“…At low temperatures, it is the imbalance between the light absorption and utilization capabilities that promotes the photodestruction of the PSII reaction centers (Oquist et al, 1987;Barber and Andersson, 1992). The stress effect is further exacerbated by the slowing down of the major photoprotection mechanisms acting at room temperature (Moll and Steinback, 1986;DemmigAdams et al, 1989;Bingsmark et al, 1992).…”

Section: Sc Ussl Onmentioning

confidence: 99%

“…If 1 /F',,,=, really monitors the rate constant (although apparent) for nonphotochemical energy dissipation, its increase in chilled R is puzzling because all regulatory mechanisms (Moll and Steinback, 1986;Demmig-Adams et al, 1989;Bingsmark et al, 1992), including active O,-scavenging enzymes (Janhke et al, 1991), are inhibited at low temperature. However, the chloroplastic Cu/ Zn superoxide dismutase activity has been found to increase with decreasing temperature (Burke and Oliver, 1992).…”

Section: Sc Ussl Onmentioning

confidence: 99%

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Cold-Resistant and Cold-Sensitive Maize Lines Differ in the Phosphorylation of the Photosystem II Subunit, CP29

et al. 1997

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l h e effects of low temperature on the relative contributions of the reaction center and the antenna activities to photosystem II (PSII) electron transport were estimated by chlorophyll fluorescence. l h e inhibition of PSll photochemistry resulted from photodamage to the reaction center and/or a reduced probability of excitation energy trapping by the reaction center. Although chill treatment did not modify the proportion of the dimeric to monomeric PSII, it destabilized its main light-harvesting complex. Full protection of the reaction center was achieved only in the presence of the phosphorylated PSll subunit, CP29. In a nonphosphorylating genotype the chill treatment led to photoinhibitory damage. l h e phosphorylation of CP29 modified neither its binding to the PSll core nor its pigment content. Phosphorylated CP29 was isolated by flat-bed isoelectric focusing. Its spectral characteristics indicated a depletion of the chlorophyll spectral forms with the highest excitation transfer efficiency to the reaction center. It is suggested that phosphorylated CP29 performs its regulatory function by an yet undescribed mechanism based on a shift of the equilibrium for the excitation energy toward the antenna.The photoconversion yields of both PSI and PSII are under the control of a regulatory network that tends to modulate their photoelectrochemical activity so as to match the rates of ATP and NADPH synthesis with the energetic requirements of the various energy-consuming pathways. The role of this regulatory network extends to the protection of the thylakoid membranes against photoinhibitory damage by preventing overreduction of the reaction centers even under light-saturating conditions Harbinson et al., 1989;Foyer et al., 1990;Seaton and Walker, 1990).Both photosystems are composed of a light-harvesting system that absorbs and transfers the excitation energy to a reaction center that catalyzes electron transfer. In contrast to PSI, in which the yield of electron transport is directly related to the degree of reduction of the P700 pool (Harbinson et al., 1989), PSII electron transport rates are essentially optimized by altering PSII light-harvesting properties. Indeed, the structure, composition, and function of the PSII antenna are very responsive to altered ATP / NADPH ratios resulting from changes in irradiance, light spectral composition, and C and N assimilation (Allen, 1992).Under light-limiting conditions the aPsII yield is kept constant at its maximum value. Adjustment of PSII electron transport rates is achieved by altering the PSII absorption cross-section. In contrast, with increasing light intensities, PSII is progressively geared to energy dissipation. Its photoconversion yield is lowered as a result of the production of additional excitation energy drains within the antenna system . It has been suggested that the thermal dissipation of excess excitation energy is associated with the synthesis of zeaxanthin (Demmig-Adams, 1990) under conditions of a high transmembrane pH gradient (Gilmore and Yamamoto...

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Section: Sc Ussl Onmentioning

confidence: 99%

Section: Sc Ussl Onmentioning

confidence: 99%

Cold-Resistant and Cold-Sensitive Maize Lines Differ in the Phosphorylation of the Photosystem II Subunit, CP29

et al. 1997

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“…Decrease in the dissipation of excitation energy through CO2 assimilation is one obvious reason (Demmig and Bjorkman 1987). Furthermore, although at least partial phosphorylation of peripheral LHCII also occurs at low temperatures, its migration to stroma lamellae is prohibited (Bingsmark et al 1990) and obviously the PSIIa-centers are not even transiently protected by this mechanism. Our general impression, however, is that the problems induced by low temperature in the chilling-sensitive pumpkin can be attributed mainly to the malfunction of the repair cycle of PSII (Tyystjarvi and Aro 1990).…”

Section: Discussionmentioning

confidence: 99%

Temperature-dependent changes in Photosystem II heterogeneity of attached leaves under high light

Aro¹,

Tyystjärvi²,

Nurmi³

1990

Physiol Plant

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Attached leaves of pumpkin (Cucurbita pepo L. cv. Jattiläismeloni) were exposed to high light intensity at room temperature (ca 23°C) and at 1°C. Fluorescence parameters and electron transport activities measured from isolated thylakoids indicated faster photoinhibition of PSII at low temperature. Separation of the α and β components of the complementary area above the fluorescence induction curve of dichlorophenyl-dimethylurea-poisoned thylakoids revealed that at low temperature only the α-centers declined during exposure to high light intensity while the content of functional β-centers remained constant. Freeze-fracture electron microscopy showed no decrease in the density of particles on the appressed exoplasmic fracture face, indicating that the photoinhibited α-centers remained in the appressed membranes at 1°C. Because of the function of the repair and protective mechanisms of PSII, strong light induced less photoinhibition at room temperature, but more complicated changes occurred in the α/β-heterogeneity of PSII. During the first 30 min at high light intensity the decrease in α-centers was almost as large as at 1°C, but in contrast to the situation at low temperature the decrease in α-centers was compensated for by a significant increase in PSIIβ-centers. Changes in the density and size of freeze-fracture particles suggest that this increase in β-centers was due to migration of phosphorylated light-harvesting complex from appressed to non-appressed thylakoid membranes while the PSII core remained in the appressed membranes. This situation, however, was only transient and was followed by a rapid decrease in the functionalβ-centers.

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Small Light-Harvesting Antenna Does Not Protect from Photoinhibition

Tyystjärvi¹,

Koivuniemi²,

Kettunen³

et al. 1991

Plant Physiol.

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High-light-induced decrease in photosystem 11 (PSII) electron transfer activity was studied in high-and low-light-grown pumpkin (Cucurbita pepo L.) plants in vivo and in vitro. The PSII lightharvesting antenna of the low-light leaves was estimated to be twice as big as that of the high-light leaves. The low-light leaves were more susceptible to photoinhibition in vivo. However, thylakoids isolated from these two plant materials were equally sensitive to photoinhibition when illuminated in the absence of external electron acceptors. Only the intensity of the photoinhibitory light and the chlorophyll concentration of the sample, not the size of the light-harvesting antenna, determined the rate of PSII photoinhibition in vitro. Because excitation of the reaction center and not only the antenna chlorophylls is a prerequisite for photoinhibition of PSII activity, independence of photoinhibition on antenna size provides support for the hypothesis (Schatz EH, Brock H, Holzwarth AR [1988] ) that the excitations of the antenna chlorophylls are in equilibrium with the excitations of the reaction centers. Better tolerance of the high-light leaves in vivo was due to a more active repair process and more powerful protective mechanisms, including photosynthesis. Apparentiy, some protective mechanism of the high-light-grown plants is at least partially active at low temperature. The protective mechanisms do not appear to function in vitro.Photoinhibition of photosynthesis (for reviews, see refs. 19 and 24) occurs when a plant is exposed to higher light intensity than experienced during growth. Photoinhibition is characterized by a decrease in PSII activity, quenching of maximum and variable fluorescence, and decrease in the quantum yield of photosynthesis. These symptoms may, however, be due to two processes: protective increase in thermal dissipation of excitation energy among the antenna pigments (for reviews of the mechanisms, see refs. 10 and 19), and photoinhibition of photosynthetic energy conversion in the reaction center.We concentrate here on the inhibition ofthe reaction center activity, using the term "photoinhibition" in a narrow sense to describe high-light-induced decrease in the electron transfer activity of PSII. (7) and from grana and stroma thylakoid vesicles enriched in PSII known to possess a big or a small light-harvesting antenna, respectively (21). However, the importance of the antenna size per se appears not to be experimentally well established, inasmuch as differences in other factors affecting the sensitivity have not been completely excluded.In this study, we tested the significance of the size of the light-harvesting antenna in susceptibility of PSII to photoinhibition. The antenna size could be affected in two ways. Photosynthesis reduces excitation density in a small antenna more effectively than in a large one. Also, a large antenna might be able to transfer more excitations to the reaction center than a small one. This effect, however, is important only if excitation transfer from...

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Phosphorylation of LHCII at Low Temperatures

Cited by 3 publications

References 3 publications

Cold-Resistant and Cold-Sensitive Maize Lines Differ in the Phosphorylation of the Photosystem II Subunit, CP29

Cold-Resistant and Cold-Sensitive Maize Lines Differ in the Phosphorylation of the Photosystem II Subunit, CP29

Temperature-dependent changes in Photosystem II heterogeneity of attached leaves under high light

Small Light-Harvesting Antenna Does Not Protect from Photoinhibition

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