Characterization of a resolved oxygen-evolving Photosystem II preparation from spinach thylakoids

Lam, Eric; Baltimore, Barbara G.; Ortiz, William; Chollar, Susan; Melis, Anastasios; Malkin, Richard

doi:10.1016/0005-2728(83)90139-1

Cited by 109 publications

(36 citation statements)

References 51 publications

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“…144 molecules of Chl per PSI reaction center in the sugar beet hybrid compared to 195 in maize (11) and 209 to 222 in spinach and pea (17,18). PSII antenna sizes were comparable to those reported previously ( 17,18 (10,15,24). These values are in excellent agreement with the value of Na(PSIIa) = 234 reported by Melis and Anderson (18).…”

Section: Discussionsupporting

confidence: 83%

Photochemical Apparatus Organization in the Chloroplasts of Two Beta vulgaris Genotypes

Abadı́a¹,

Glick²,

Taylor³

et al. 1985

Plant Physiol.

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The composition and structural orpnization of thylakoid membranes of a low chlorophyll mutant of Beta rulgaris was investigated using spectroscopic, kinetic and electrophoretic techniques. The data obtained were compared with those of a standard Fl hybrid of the same species. The mutant was depleted in chlorophyll b relative to the hybrid and it had a higher photosystem II/photosystem I reaction center (Q/P7") (1,12,17,26).Investigation of the effects of mutations of genes coding for specific components of the thylakoid membrane permit greater precision in the interpretation of the structural/functional role of that component than would be possible for many environmental perturbations of thylakoid structure. In our laboratory (N. T.) we are studying currently a low Chl sugar beet mutant which exhibits high rates ofphotosynthesis and electron transport per unit Chl similar to those described by Miles (23): the mutation apparently affects some specific polypeptides of the LHCP.3 Here, we characterize the structural organization of thylakoid membranes of the low Chl mutant by combining spectroscopic analysis with gel electrophoresis. The mutant genotype is compared with the standard sugar beet genotype (an Fl hybrid) used in this laboratory, for which a large amount of biochemical and physiological data is available. Spectroscopic estimates of the amounts of Chl associated with PSII and PSI, and of the stoichiometries of the reaction centers of the two photosystems were compared with those obtained using three different gel electrophoresis systems. MATERIALS AND METHODS

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Section: Discussionsupporting

confidence: 83%

Photochemical Apparatus Organization in the Chloroplasts of Two Beta vulgaris Genotypes

Abadı́a¹,

Glick²,

Taylor³

et al. 1985

Plant Physiol.

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“…It has been shown previously, for example, that a significant amount of catalase is present in PS I1 preparations but it has no apparent role in PS I1 [28]. The large number of polypeptides found in our experiments differs from those of other laboratories who found 9-13 polypeptides on a one-dimensional gel stained with Coomassie blue [32,33]. One might assume that probably some proteolysis occurred during isolation, which multiplied the spots on our gels.…”

contrasting

confidence: 56%

Analysis of the polypeptide composition of grana and stroma thylakoids by two-dimensional gel electrophoresis. Distribution of photosystem II between grana and stroma lamellae

1987

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The polypeptide composition of whole thylakoids and membrane subfragments was studied by using a modified two-dimensional gel electrophoresis technique of O'Farrell [J. Biol. Chem. 250,[4007][4008][4009][4010][4011][4012][4013][4014][4015][4016][4017][4018][4019][4020][4021] (1 975)]. The modifications were lithium dodecyl sulphate solubilization instead of SDS, reverse isofocusing and sensitive silver staining procedure. This high-resolution technique allowed us to separate and identify about 170 polypeptides of thylakoid membranes. After separating grana and stroma thylakoids it was found that both types of lamellae contained nearly equal amounts of polypeptides, but about 70 polypeptides were different in the two preparations. In grana thylakoids, 54 polypeptides out of 95 were found to be mainly present in grana and 31 of them were only present in grana preparations. In stroma membranes, 43 polypeptides out of 99 were mainly present in stroma lamellae and 38 of these polypeptides were exclusively present in stroma lamellae. In a functional photosystem I1 preparation, 61 individual polypeptides could be distinguished. Most of these polypeptides were present in both grana and stroma lamellae, but 22 of them were more pronounced in grana than in stroma lamellae. 9 polypeptides of photosystem I1 were distinctly different in grana and stroma lamellae, and these differences may connect closely with the functional differences of photosystem I1 in the two types of thylakoids.Our knowledge about the structural and functional organization of the photosynthetic membrane has been changed substantially during the last few years. Until the beginning of this decade it was the generally accepted concept that Photosystems (PS) I and 11 were located in stochiometrically equal amounts in the grana region of chloroplasts, while stroma exposed thylakoids contained mainly PS I only (1, 21. From the early '80s this concept has been dramatically changed. As an early step in this process it was recognized that the two photosystems do not contribute equally in the chloroplast lamellae of higher plants [3 -51.Other results have suggested that PS I is totally excluded from the grana partition region and is located exclusively in the stroma exposed thylakoids [6 -81. Recent evidence suggests that about 20% of PS I1 are still localized in stroma thylakoids [8,9], and these PS I1 are markedly different from those which are in the granal region [8, 91. The concept of PS I1 heterogeneity was developed to interpret the biphasic nature of the primary PS I1 photoactivity [lo-121. Different aspects of PS I1 heterogeneity have been addressed during the last few years and it is now believed that PS I1 occurs in the forms of two structural/functional configurations, termed PS 11, and PS 11, [S, 13, 141. Results obtained by the kinetic analysis of the primary photoactivity of fractionated thylakoids indicate that PS 11, is exclusively located in the membranes of grana partitions, while PS 11, and PS I are located in stroma exposed thylakoids [S,...

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“…The nature of the "molecular switch" that allows this interconversion to occur is unknown but is likely to involve a change in the environment of the heme or a minor conformational change of the PSII complex as indicated from in vitro studies (25)(26)(27)(28). One obvious mechanism could involve protonation/deprotonation events associated with changes in local pH.…”

Section: Discussionmentioning

confidence: 99%

A functional model for the role of cytochrome b559 in the protection against donor and acceptor side photoinhibition.

Barber

Rivas

1993

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

148

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A quinone-independent photoreduction of the low potential form of cytochrome b559 has been studied using isolated reaction centers of photosystem II. Under anaerobic conditions, the cytochrome can be fully reduced by exposure to strong illumination without the addition of any redox mediators. Under high light conditions, the extent and rate of the reduction is unaffected by addition of the exogenous electron donor Mn2+ and, during this process, no irreversible damage occurs to the reaction center. However, prolonged illumination in strong light brings about irreversible bleaching of chlorophyll, indicative of photoinhibitory damage. When the cytochrome is fully reduced and excess Mn2+ is present, the effect of moderate light is to facilitate the photoaccumulation of reduced pheophytin. The dark reoxidation of the reduced cytochrome is very slow under anaerobic conditions but significantly speeded up on addition of oxidized 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone. From these results it is suggested that the low potential form of cytochrome b559 can accept electrons directly from reduced pheophytin and in so doing help to protect the reaction center against acceptor side photoinhibition as suggested by Nedbal et al. [Nedbal, J., Samson, G. & Whitmarsh, J. (1992) Proc. Natl. Acad. Sci. USA 89, 7929-7933]. This conclusion has been incorporated into a model that further suggests that in its high potential form the cytochrome primarily acts to protect against donor side photoinhibition due to increased lifetime of highly oxidized species as previously proposed by Thompson and Brudvig [Thompson, L. & Brudvig, G. W. (1988) Biochemistry 27, 6653-6658]. The particular feature of our scheme is that it incorporates reversible interconversion between the two redox forms so as to protect against either type of photoinhibition.

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Characterization of a resolved oxygen-evolving Photosystem II preparation from spinach thylakoids

Cited by 109 publications

References 51 publications

Photochemical Apparatus Organization in the Chloroplasts of Two Beta vulgaris Genotypes

Photochemical Apparatus Organization in the Chloroplasts of Two Beta vulgaris Genotypes

Analysis of the polypeptide composition of grana and stroma thylakoids by two-dimensional gel electrophoresis. Distribution of photosystem II between grana and stroma lamellae

A functional model for the role of cytochrome b559 in the protection against donor and acceptor side photoinhibition.

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