Effect of phosphorylation on the thermal and light stability of the thylakoid membranes

Várkonyi, Zsuzsanna; Nagy, Gergely; Lambrev, Petar H.; Kiss, Anett Z.; Szekély, Noemi; Rosta, L.; Garab, Győző

doi:10.1007/s11120-008-9386-y

Cited by 22 publications

(10 citation statements)

References 47 publications

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“…A similar structure was previously observed as a native form of LHCII in thylakoid membranes (21). The structural alteration conferred by LHCII phosphorylation (11,(22)(23)(24) could cause these aggregations. Furthermore, FLIM and spectroscopic measurements indicated that the phospho-LHCII was energy-dissipative as compared with unphosphorylated LHCII (Fig.…”

Section: Chlorophyll Fluorescence Lifetime Of Dissociated Phospho-lhcsupporting

confidence: 76%

Live-cell imaging of photosystem II antenna dissociation during state transitions

Iwai

Yokono²,

Inada³

et al. 2009

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

123

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Plants and green algae maintain efficient photosynthesis under changing light environments by adjusting their light-harvesting capacity. It has been suggested that energy redistribution is brought about by shuttling the light-harvesting antenna complex II (LHCII) between photosystem II (PSII) and photosystem I (PSI) (state transitions), but such molecular remodeling has never been demonstrated in vivo. Here, using chlorophyll fluorescence lifetime imaging microscopy, we visualized phospho-LHCII dissociation from PSII in live cells of the green alga Chlamydomonas reinhardtii. Induction of energy redistribution in wild-type cells led to an increase in, and spreading of, a 250-ps lifetime chlorophyll fluorescence component, which was not observed in the stt7 mutant incapable of state transitions. The 250-ps component was also the dominant component in a mutant containing the light-harvesting antenna complexes but no photosystems. The appearance of the 250-ps component was accompanied by activation of LHCII phosphorylation, supporting the visualization of phospho-LHCII dissociation. Possible implications of the unbound phospho-LHCII on energy dissipation are discussed.photosynthesis | fluorescence lifetime imaging microscopy | green algae | light-harvesting | energy dissipation I n the thylakoid membranes of chloroplasts, photosystems I and II (PSI and PSII) work in concert to carry out photosynthetic electron transfer from water to NADP + . For efficient photosynthesis under changing light conditions, balancing absorbed light energy between the two photosystems, or state transition, is important (1-3). The plastoquinone (PQ) pool, an intersystem electron carrier, monitors changes in light quality and quantity and activates a protein kinase for light-harvesting complex (LHC) II (3-5). LHCII phosphorylation leads to a decrease in PSII light absorption (6, 7), which occurs on a timescale of minutes without any changes in gene expression. The decrease is therefore considered to be due to the reorganization of the PSII antenna system, such as dissociation of phospho-LHCII from PSII.The fate of dissociated phospho-LHCII has been investigated in vitro. Subfractionation of phosphorylated thylakoid membranes showed that the stroma lamella (non-appressed) fraction, where PSI was predominantly located, contained more phospho-LHCII than the grana (appressed) fraction, where PSII was predominantly located (8-10). Isolation of PSII under PQ pool-oxidizing conditions provided the evidence that unphospho-LHCII remained bound to PSII, whereas under PQ pool-reducing conditions phospho-LHCII was dissociated from PSII (11). Isolation of PSI under the same conditions revealed that the dissociated LHCII (including both major and minor LHCII) were reassociated with PSI (12). Thus, state transitions are accompanied by LHCII relocation between the two photosystems.However, because such LHCII migrations have been observed only in vitro, it still remains to be uncovered what happens during the LHCII migration in vivo. Does LHCII really disso...

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Section: Chlorophyll Fluorescence Lifetime Of Dissociated Phospho-lhcsupporting

confidence: 76%

Live-cell imaging of photosystem II antenna dissociation during state transitions

Iwai

Yokono²,

Inada³

et al. 2009

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

123

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“…The molecular mechanism of LHCIIb to regulate its different functions is realised via changes in the macro-molecular structures in the membrane and the phosphorylation-dephosphorylation of LHCIIb (Allen 2005b;Horton et al 2008). This multi-functional characteristic ensures highly efficient light harvesting and sensibility against the situations of over-excitation (Bassi and Caffarri 2000;Szabo et al 2008;Varkonyi et al 2009). …”

Section: Sensing the Change-variation In Photosynthetic Function Medimentioning

confidence: 99%

The hidden function of photosynthesis: a sensing system for environmental conditions that regulates plant acclimation responses

Pfannschmidt

Yang

2012

Protoplasma

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Plants convert light energy from the sun into chemical energy by photosynthesis. Since they are sessile, they have to deal with a wide range of conditions in their immediate environment. Many abiotic and biotic parameters exhibit considerable fluctuations which can have detrimental effects especially on the efficiency of photosynthetic light harvesting. During evolution, plants, therefore, evolved a number of acclimation processes which help them to adapt photosynthesis to such environmental changes. This includes protective mechanisms such as excess energy dissipation and processes supporting energy redistribution, e.g. state transitions or photosystem stoichiometry adjustment. Intriguingly, all these responses are triggered by photosynthesis itself via the interplay of its light reaction and the Calvin-Benson cycle with the residing environmental condition. Thus, besides its primary function in harnessing and converting light energy, photosynthesis acts as a sensing system for environmental changes that controls molecular acclimation responses which adapt the photosynthetic function to the environmental change. Important signalling parameters directly or indirectly affected by the environment are the pH gradient across the thylakoid membrane and the redox states of components of the photosynthetic electron transport chain and/or electron end acceptors coupled to it. Recent advances demonstrate that these signals control post-translational modifications of the photosynthetic protein complexes and also affect plastid and nuclear gene expression machineries as well as metabolic pathways providing a regulatory framework for an integrated response of the plant to the environment at all cellular levels.

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“…In case of the unbalanced functioning of PSII and PSI a redox-controlled energy redistribution occurs between the two photosystems, a process known as state transition, during which large structural reorganizations have been shown to occur (Allen 2003;Allen and Forsberg 2001;Chuartzman et al 2008;Iwai et al 2010;Rochaix 2007;Várkonyi et al 2009). In plants exposed to excess light, associated with the non-photochemical quenching of the chlorophyll singlet excited state, substantial reorganizations have been observed (Barzda et al 1996;Dall'Osto et al 2005;Grudziński et al 2002;Gruszecki et al 2006;Horton et al 2008;Horton et al 1996;Istokovics et al 1997;Lambrev et al 2007a).…”

Section: Introductionmentioning

confidence: 99%

Dynamic properties of photosystem II membranes at physiological temperatures characterized by elastic incoherent neutron scattering. Increased flexibility associated with the inactivation of the oxygen evolving complex

et al. 2011

Self Cite

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Elastic incoherent neutron scattering (EINS), a non-invasive technique which is capable of measuring the mean square displacement of atoms in the sample, has been widely used in biology for exploring the dynamics of proteins and lipid membranes but studies on photosynthetic systems are scarce. In this study we investigated the dynamic characteristics of Photosystem II (PSII) membrane fragments between 280 and 340 K, i.e., in the physiological temperature range and in the range of thermal denaturation of some of the protein complexes. The mean square displacement values revealed the presence of a hydration-sensitive transition in the sample between 310 and 320 K, suggesting that the oxygen evolving complex (OEC) plays an important role in the transition. Indeed, in samples in which the OEC had been removed by TRIS- or heat-treatments (323 and 333 K) no such transition was found. Further support on the main role of OEC in these reorganizations is provided by data obtained from differential scanning calorimetry experiments, showing marked differences between the untreated and TRIS-treated samples. In contrast, circular dichroism spectra exhibited only minor changes in the excitonic interactions below 323 K, showing that the molecular organization of the pigment-protein complexes remains essentially unaffected. Our data, along with earlier incoherent neutron scattering data on PSII membranes at cryogenic temperatures (Pieper et al., Biochemistry 46:11398-11409, 2007), demonstrate that this technique can be applied to characterize the dynamic features of PSII membranes, and can be used to investigate photosynthetic membranes under physiologically relevant experimental conditions.

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Effect of phosphorylation on the thermal and light stability of the thylakoid membranes

Cited by 22 publications

References 47 publications

Live-cell imaging of photosystem II antenna dissociation during state transitions

Live-cell imaging of photosystem II antenna dissociation during state transitions

The hidden function of photosynthesis: a sensing system for environmental conditions that regulates plant acclimation responses

Dynamic properties of photosystem II membranes at physiological temperatures characterized by elastic incoherent neutron scattering. Increased flexibility associated with the inactivation of the oxygen evolving complex

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