Extrinsic polypeptides of the chloroplast oxygen evolving complex constitute the tetrameric ESs particles of higher plant thylakoids

Simpson, David J. W.; Andersson, Bertil

doi:10.1007/bf02907319

Cited by 30 publications

(12 citation statements)

References 26 publications

(21 reference statements)

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“…3 gives various close-up views of the protrusions attributed to the OEC extrinsic proteins. The tetrameric organization of these protrusions at the surface of the dimeric supercomplex is reminiscent of that revealed earlier by freeze-etch studies (25,26). The densities assigned to PsbP and PsbQ extend about 50 Å from the lumenal surface of the supercomplex, whereas the density attributed to the PsbO protein is about 40 Å from the surface.…”

Section: -å Three-dimensional Map Of the Lhcii-psii Supercomplex Issupporting

confidence: 70%

Three-dimensional Electron Cryo-microscopy Study of the Extrinsic Domains of the Oxygen-evolving Complex of Spinach

Nield¹,

Balsera²,

Rivas³

et al. 2002

Journal of Biological Chemistry

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Three independent three-dimensional reconstructions of the spinach photosystem II-light-harvesting complex supercomplex were derived from single particle analyses of non-stained, vitrified samples imaged by electron microscopy. Each reconstruction was found to differ significantly in the composition of the lumenal oxygen-evolving complex extrinsic proteins. From difference mapping, aided by electron microscopy of negatively stained selectively washed samples, regions of density were assigned to the PsbO and PsbP/PsbQ proteins. Interpretation of the density assigned to the PsbO protein was explored using computer-aided structural predictions. PsbO is calculated to be mainly a ␤-protein (38% ␤) composed of two domains within an overall elongated shape (Pazos, F., Heredia, P. Plants, algae, and cyanobacteria are able to use the energy of visible light to break the O-H bond of water and produce molecular oxygen. Photosystem II (PSII), 1 a multi-subunit transmembrane protein complex (1), carries out this difficult and thermodynamically demanding reaction. The water oxidase activity of PSII is driven by a series of electron transfer reactions. Light-induced primary charge separation gives rise to the radical pair P680 ⅐ ϩ /Pheo ⅐ Ϫ where P680 is a high potential form of chlorophyll a (1 V or more) and Pheo is a pheophytin a molecule. Electron flow proceeds from Pheo ⅐ Ϫ to the plastoquinone molecules Q A and Q B . When Q B is doubly reduced, it is protonated and replaced by an oxidized plastoquinone (PQ) molecule from the PQ pool in the membrane. On the electron donor side, P680 ⅐ ϩ is reduced by a tetramanganese cluster (Mn) 4 via a redox-active tyrosine Y z . These redox-active cofactors are bound to the D1 and D2 reaction center proteins and are arranged in such a way that electron flow occurs across the membrane with the water oxidation site located on the lumenal/periplasmic surface and PQ reduction close to the stromal/ cytoplasmic surface (2).The (Mn) 4 cluster is the catalytic site for water oxidation and is ligated to the D1 protein in the region of Y Z (D1 Tyr-161) (3). This inorganic group is stabilized by an extrinsic 33-kDa protein (PsbO) encoded by the psbO gene. Also associated with the oxygen-evolving complex (OEC) are at least two other extrinsic proteins, the 23-kDa (PsbP) and 17-kDa (PsbQ) proteins in plants and green algae and the 15-kDa (PsbV) and 11-kDa (PsbU) proteins in cyanobacteria (4). Together the OEC extrinsic proteins provide an optimal ionic (Cl Ϫ and Ca 2ϩ ) environment for the water oxidation reaction (3), although there is a lack of clear knowledge about the specific function and activity of these proteins during the process of water oxidation and oxygen evolution. In the case of higher plants, little is known about the structure of the OEC proteins (5) or about their specific location and arrangement in relation to the intrinsic subunits of PSII. In the case of the PsbO protein, there have been assignments of its secondary structure based on spectroscopic studies (6). Fourier transfo...

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Section: -å Three-dimensional Map Of the Lhcii-psii Supercomplex Issupporting

confidence: 70%

Three-dimensional Electron Cryo-microscopy Study of the Extrinsic Domains of the Oxygen-evolving Complex of Spinach

Nield¹,

Balsera²,

Rivas³

et al. 2002

Journal of Biological Chemistry

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“…It is now generally accepted that all PSI and CF, is located in stroma Abbreviations: CF 1 = extrinsic part of chloroplast coupling factor; Chl = chlorophyll; EFs = endoplasmic fracture face of stacked thylakoids; kD = kilodaltons; LHCI = light harvesting chlorophyll-protein of PSI; LHCII = light harvesting chlorophyll-protein of PSII; PAGE = polyacrylamide gel electrophoresis; PSI = photosystem I; PSII = photosystem It; SDS = sodium dodecyl sulphate. lamellae, while most of the PSII, along with its antenna LHCII and water splitting complex, is located in the appressed grana membranes (2,3,15,27). Such fractionation experiments have been independently confirmed by immunogold labelling of thin sections (17,29,30) and freezefracture electron microscopy of mutants (25,26).…”

Section: Introductionmentioning

confidence: 77%

Characterisation of stroma membranes from Zea mays L. chloroplasts

Bassi

Giacometti

Simpson

1988

Carlsberg Res. Commun.

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Stroma lamellae were isolated from dark-adapted maize seedling leaves by mechanical disruption of isolated, stacked thylakoids. Their chlorophyll-protein composition was analysed by non-denaturing SDS-PAGE and revealed the presence of Chla-Pl, LHCI-730, LHCI-680 and a small amount of LHCII. Also present were the chlorophyll-protein complexes Chl~-P 1', LHCI-730* and LHCII**. This is consistent with the model proposed for PSI based on detergent isolation, and confirms the presence of LHCI-680 in PSI in situ. Re-electrophoresis of the chlorophyll-protein bands under denaturing conditions, revealed three low molecular weight PSI polypeptides which were always found associated with LHCI-730. Quantitation of PSII polypeptides by immuneblot assay showed that stroma lamellae contained 30 times less than grana lamellae on a chlorophyll basis. This indicates that most of the LHCII was associated with PSI, but the oligomeric form (LHCII**) in stroma lamellae was stable only in the presence of Mg * § in contrast to LHCII** from granal membranes. This is correlated with the absence of a 26 kD LHCII polypeptide from stroma lamellae.

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“…Chloroplast membranes isolated after transport (200 pg Chl/ml) were washed for 30 rnin at room temperature. The wash media were: 0.25 mM NaC1,lO mM Mes pH 6.5; 1 M NaC1,IO mM Mes pH 6.5; 1 M CaCl,, 10 mM Mes pH 6.5 and 0.8 M Tris pH 8.4, respectively [37]. The control thylakoids were washed in 10 mM Mes/KOH, pH 6.5.…”

Section: Membrane Fractionation Proceduresmentioning

confidence: 99%

“…The incubation of thylakoid membranes with several different salt solutions causes liberation of some or all of the extrinsic membrane polypeptides as described for the proteins of the oxygen-evolving complex [37]. Our aim was to investigate the stability of the binding of HSP 22 to thylakoid membranes in the presence of salts.…”

Section: Hsp 22 Is An Intrinsic Membrane Protein or Alternatively Amentioning

confidence: 99%

Evidence for the localization of the nuclear‐coded 22‐kDa heat‐shock protein in a subfraction of thylakoid membranes

Adamska

Kloppstech

1991

European Journal of Biochemistry

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The precursor to the nuclear-coded 22-kDa heat-shock protein of chloroplasts (HSP 22) has been transported into isolated intact chloroplasts from heat-shocked plants. The localization of the mature protein in the chloroplast membrane was investigated. We have shown that the processed HSP 22 of pea was not bound to envelopes and found predominantly in thylakoid membranes. The binding of HSP 22 was stable in the presence of high salt concentrations. Solubilization of thylakoid membranes with Triton X-100 and phase partitioning with Triton X-114 indicate an intrinsic localization of HSP 22 or, alternatively, a non-covalent association with integral membrane protein(s). After fractionation into grana and stroma lamellae, HSP 22 was found mostly in the grana-membrane subfraction.All organisms respond to heat by inducing the synthesis of a group of proteins defined as the heat-shock proteins (HSP). These proteins, ranging in molecular mass over 10 -I1 0 kDa, have been classified into five distinct families [I, 21 and have been detected in both procaryotic and eucaryotic cells. The occurrence of heat-shock proteins in procaryotes raised the interesting question as to whether plastids, considered to be of procaryotic descent, might also possess heatshock proteins and, if so, whether these would be coded by nuclear or plastid DNA.To date all known heat-shock proteins in plants are nuclear-coded and translated on cytosolic ribosomes. Also the so-called 'chaperonin' which is related to heat-shock proteins and whose level of mRNA is enhanced by a heat treatment is of nuclear origin [3]. Reports on the detection of plastid-coded heat-shock proteins in Acetabularia [4] and higher plants [5] need confirmation by more elaborate experiments.In higher plants low-molecular-mass heat-shock proteins (15 -30 kDa) represent a particularly prominent and heterogeneous group coded for by multigene families 16 -91. The majority of these low-molecular-mass proteins are localized in the cytosol and become associated with the cytoskeleton during heat shock [lo] or incorporated into heat-shock granules [I I]. Plastid-localized heat-shock proteins with similarities to the cytosolic small-molecular-mass heat-inducible proteins have been described in pea [12, 131, Chlamydomonas [12] Abbreviations. CF1, extrinsic coupling factor of ATP synthethase; HSP 22, 22-kda heat-shock protein; LHC 11, light-harvesting chlorophyll a/b complex 11; PS I and PS 11, photosystems I and 11; Triton X-100, octylphenoxypolyethoxyethanol; Triton X-114, octylphenolpolyethyleneglycol ether.Enzymes. ATP synthetase (EC 3.6.1.34); ribulose 1,5-bisphosphate carboxylase (EC 4.1.1.39).[I61 and petunia [17]. However, the localization of these proteins within the chloroplasts of higher plants is controversial. Vierling et al. [13,18, 191 have found both after in vitro transport or by using polyclonal antibodies that the processed 22-kDa heat-shock protein (HSP 22) of pea remains to over 90% unbound in the stroma fraction and that the remainder is only loosely associated wi...

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Extrinsic polypeptides of the chloroplast oxygen evolving complex constitute the tetrameric ESs particles of higher plant thylakoids

Cited by 30 publications

References 26 publications

Three-dimensional Electron Cryo-microscopy Study of the Extrinsic Domains of the Oxygen-evolving Complex of Spinach

Three-dimensional Electron Cryo-microscopy Study of the Extrinsic Domains of the Oxygen-evolving Complex of Spinach

Characterisation of stroma membranes from Zea mays L. chloroplasts

Evidence for the localization of the nuclear‐coded 22‐kDa heat‐shock protein in a subfraction of thylakoid membranes

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