Regulation of photosynthesis by reversible phosphorylation of the light-harvesting chlorophyll <i>a</i>/<i>b</i> protein

Bennett, John

doi:10.1042/bj2120001

Cited by 272 publications

(88 citation statements)

References 96 publications

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“…This conformational change induces the dissociation of the phospho-LHCII trimer into monomeric phospho-LHCII. The monomers are free to migrate from PSII to PSI (55). After dephosphorylation, unphosphorylated LHCII monomers may trimerize at the periphery of PSII.…”

Section: Identification Of Endogenous Substrates For Synptpmentioning

confidence: 99%

A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

Mukhopadhyay

Kennelly

2011

The Journal of Biochemistry

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The predicted protein product of open reading frame slr0328 from Synechocystis sp. PCC 6803, SynPTP, possesses significant amino acid sequence similarity with known low molecular weight protein tyrosine phosphatases (PTPs). To determine the functional properties of this hypothetical protein, open reading frame slr0328 was expressed in Escherichia coli. The purified recombinant protein, SynPTP, displayed its catalytic phosphatase activity towards several tyrosine, but not serine, phosphorylated exogenous protein substrates. The protein phosphatase activity of SynPTP was inhibited by sodium orthovanadate, a known inhibitor of tyrosine phosphatases, but not by okadaic acid, an inhibitor for many serine/threonine phosphatases. Kinetic analysis indicated that the K m and V max values for SynPTP towards p-nitrophenyl phosphate are similar to those of other known bacterial low molecular weight PTPs. Mutagenic alteration of the predicted catalytic cysteine of PTP, Cys 7 , to serine abolished enzyme activity. Using a combination of immunodetection, mass spectrometric analysis and mutagenically altered Cys 7 SerAsp 125 Ala-SynPTP, we identified PsaD (photosystem I subunit II), CpcD (phycocyanin rod linker protein) and phycocyanin-a and -b subunits as possible endogenous substrates of SynPTP in this cyanobacterium. These results indicate that SynPTP might be involved in the regulation of photosynthesis in Synechocystis sp. PCC 6803.

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Section: Identification Of Endogenous Substrates For Synptpmentioning

confidence: 99%

A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

Mukhopadhyay

Kennelly

2011

The Journal of Biochemistry

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“…This is due mainly to increases in nonradiative (thermal) deactivation of absorbed photosynthetically active excitation in the chl antennae complex (9)(10)(11) and/or at the reaction center (29,30). An increase in the transfer of energy from PSII to nonfluorescent PSI at the level of the light harvesting Chl complexes can also result in a lowering of maximal fluorescence yield (1,15). It is reasonable to propose that an irradiance-dependent decrease in maximal fluorescence yield (PSII centers closed) would be accompanied by a quenching of minimal yield (PSI1 centers open).…”

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confidence: 99%

Analysis of Changes in Minimal and Maximal Fluorescence Yields with Irradiance and O₂ Level in Tobacco Leaf Tissue

Peterson¹

1991

Plant Physiol.

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The responses of minimal and maximal fluorescence yields of chlorophyll a to irradiance of actinic white light were determined by pulse modulated fluorimetry in leaf discs from tobacco, Nkotina tabacum, at 1.6, 20.5, and 42.0% (v/v) 02. Steady-state maximal fluorescence yield (Fm', measured during a saturating light pulse) declined with increasing irradiance at all 02 levels. In contrast, the steady-state minimal fluorescence yield (Fo', measured during a brief dark interval) increased with irradiance relative to that recorded for the fully dark-adapted leaf (Fo) or that observed after 5 minutes of darkness (Fo*). The relative magnitude of this increase was somewhat greater and extended to higher irradiances at the elevated 02 levels compared with 1.6% 02.Suppression of Fo' was only observed consistently at saturating irradiance. The results are interpreted in terms of the occurrence of photosystem 11 units possessing exceedingly slow turnover times (i.e. "Inactive" units). Inactive units play an important role, along with thermal deactivation of excited chlorophyll, in determining the response of in vivo fluorescence yield to changes in irradiance. Also, a significant interactive effect of02 concentration and the presence or absence of far red light on oxidation of photosystem 11 acceptors in the dark was noted.Considerable interest has centered recently on the relationship between the intensity ofChl a fluorescence and efficiency of photochemistry in green leaves (7,9,10,12,16,20,21,30 fluorescence emission for available excitation (8,16,25). Under these circumstances fluorescence yield is maximal and qp = 0. Conversely, when the QA pool is completely oxidized then photochemistry is favored so that fluorescence yield is minimal (qp = 1). Typically, the ratio of maximal to minimal fluorescence yields is 5 to 6 in fully dark-adapted green leaves.As the irradiance of continuous actinic illumination increases the maximum fluorescence yield obtainable progressively decreases (i.e. "nonphotochemical" quenching coefficient, qN, increases from 0 to 1) (4,15,25). This is due mainly to increases in nonradiative (thermal) deactivation of absorbed photosynthetically active excitation in the chl antennae complex (9-11) and/or at the reaction center (29,30). An increase in the transfer of energy from PSII to nonfluorescent PSI at the level of the light harvesting Chl complexes can also result in a lowering of maximal fluorescence yield (1,15). It is reasonable to propose that an irradiance-dependent decrease in maximal fluorescence yield (PSII centers closed) would be accompanied by a quenching of minimal yield (PSI1 centers open). The degree of quenching of minimal fluorescence yield relative to maximal yield would depend upon the mechanism of quenching and the role that interconversion among heterogeneous PSII states (29, 30) might play in balancing light harvesting with the capacity of stromal reactions to utilize the products NADPH and ATP (12).This report describes results obtained with tobacco leaf tissue in...

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“…Two models have been proposed to explain the movement of LHCII. According to one model, alteration in the surface charge upon phosphorylation leads to structural changes of the thylakoid membrane and results in the movement of phospho-LHCII away from grana stacks (7)(8)(9). According to another model, the net movement of LHCII toward PSI in State 2 is caused by PSII with higher affinity for unphosphorylated LH-CII and PSI with higher affinity for phospho-LHCII, therefore movement of phospho-LHCII is a question of molecular recognition (6).…”

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confidence: 99%

Light-harvesting Complex II Binds to Several Small Subunits of Photosystem I

Zhang¹,

Scheller²

2004

Journal of Biological Chemistry

119

103

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Mobile light-harvesting complex II (LHCII) is implicated in the regulation of excitation energy distribution between Photosystem I (PSI) and Photosystem II (PSII) during state transitions. To investigate how LHCII interacts with PSI during state transitions, PSI was isolated from Arabidopsis thaliana plants treated with PSII or PSI light. The PSI preparations were made using digitonin. Chemical cross-linking using dithio-bis(succinimidylpropionate) followed by diagonal electrophoresis and immunoblotting showed that the docking site of LHCII (Lhcb1) on PSI is comprised of the PSI-H, -L, and -I subunits. This was confirmed by the lack of energy transfer from LHCII to PSI in the digitonin-PSI isolated from plants lacking PSI-H and -L. Digitonin-PSI was purified further to obtain an LHCII⅐PSI complex, and two to three times more LHCII was associated with PSI in the wild type in State 2 than in State 1. Lhcb1 was also associated with PSI from plants lacking PSI-K, but PSI from PSI-H, -L, or -O mutants contained only about 30% of Lhcb1 compared with the wild type. Surprisingly, a significant fraction of the LHCII bound to PSI in State 2 was not phosphorylated. Cross-linking prior to sucrose gradient purification resulted in copurification of phosphorylated LHCII in the wild type, but not with PSI from the PSI-H, -L, and -O mutants. The data suggest that migration of LHCII during state transitions cannot be explained sufficiently by different affinity of phosphorylated and unphosphorylated LHCII for PSI but is likely to involve structural changes in thylakoid organization.In oxygenic photosynthesis two photosystems, PSI 1 and PSII, work in series to convert light energy into chemical energy. PSI is also involved in cyclic electron transport without the participation of PSII, and this process serves to produce additional ATP and to regulate the transthylakoidal proton gradient (1), but in plants this is a minor part of the electron transport. In linear electron transport, PSI and PSII must operate with the same rate, but natural environmental conditions, such as the quality and quantity of light, are constantly fluctuating, and this may alter the balance between the two photosystems. The two photosystems have different absorption spectra, and therefore a change in light quality may favor one photosystem over the other. However, plants can balance the excitation energy distribution between the two photosystems via a mechanism known as state transitions, which was discovered more than 30 years ago (2-4). If PSII is overexcited relative to PSI, the plastoquinone pool becomes overreduced, and this will activate a kinase that phosphorylates a mobile pool of light-harvesting complex II (LHCII), leading to the lateral movement of LHCII in favor of PSI. This is the so-called "State 2," in which the PSII antenna is smaller and the PSI antenna is larger than in State 1 (5, 6). State 1 is obtained when PSI is preferentially excited, which leads to oxidation of the plastoquinone pool and inactivation of the LHCII kinase. The phosph...

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Regulation of photosynthesis by reversible phosphorylation of the light-harvesting chlorophyll a/b protein

Cited by 272 publications

References 96 publications

A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

Analysis of Changes in Minimal and Maximal Fluorescence Yields with Irradiance and O₂ Level in Tobacco Leaf Tissue

Light-harvesting Complex II Binds to Several Small Subunits of Photosystem I

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Regulation of photosynthesis by reversible phosphorylation of the light-harvesting chlorophyll a/b protein

Cited by 272 publications

References 96 publications

A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

Analysis of Changes in Minimal and Maximal Fluorescence Yields with Irradiance and O2 Level in Tobacco Leaf Tissue

Light-harvesting Complex II Binds to Several Small Subunits of Photosystem I

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Analysis of Changes in Minimal and Maximal Fluorescence Yields with Irradiance and O₂ Level in Tobacco Leaf Tissue