Photosystem II reaction center

Campbell D, Eriksson MJ, Oquist G, Gustafsson P, Clarke AK (1998) The cyanobacterium Synechococcus resists UV-B by exchanging photosystem II reaction-center D1 proteins. Proc... 

A recent study (Booth PJ, Crystall B, Giorgi LB, Barber J, Klug DR, Porter G (1990) Biochim. Biophys. Acta 1016 141) has shown that the free energy difference of the primary electron transfer is dominated by entropic contributions in photosystem II reaction centers as in bacterial reaction centers (Woodbury NWT, Parson WW (1984) Biochim. Biophys. Acta 767 345), so that the interpretation of the rate temperature dependenee should be revised. 

Although the structures of the plant reaction centers are not yet known in detail, photosystem II reaction centers resemble reaction centers of purple bacteria in several ways. The amino acid sequences of their two major polypeptides are homologous to those of the two polypeptides that hold the pigments in the bacterial reaction center. Also, the reaction centers of photosystem II contain a nonheme iron atom and two molecules of plastoquinone, a quinone that is closely related to ubiquinone (see fig. 15.10), and they contain one or more molecules of pheophytin a and several... 

If the photosystem II reaction center transfers only one electron at a time, how does it assemble the four oxidizing equivalents needed for oxidation of H20 to 02 One possibility is that several different photosystem II reaction centers cooperate, but this seems not to happen. Instead, each reaction center progresses independently through a series of oxidation states, advancing to the next state each time it absorbs a photon. In this event 02 evolution would occur only when a reaction center has accumulated four oxidizing equivalents. Support for this conclusion comes from measurements made by Pierre Joliot of the amount of 02 evolved on each flash when chloroplasts are excited with a series of short flashes after a period of darkness. No 02 is released on the first or second flashes (fig. 15.21), but on the third flash, there is a burst of 02. After this, the amount of 02 released on each flash oscillates, going through a maximum every fourth flash. 

Bessel Kok pointed out that this pattern can be explained if the photosystem II reaction center cycles through five different oxidation states, S0 through S4, as shown in figure 15.22. When the system reaches state S4, 02 is given... 

Booij-James IS, Dube SK, Jansen MAK, Edelman M, Mattoo AK. 2000. Ultraviolet-B radiation impacts light-mediated turnover of the photosystem II reaction center heterodimer in Arabidopsis mutants altered in phenolic metabolism. Plant Physiol 124 1275-1284. 

Nanba, O. and K. Satoh (1987). Isolation of a photosystem II reaction center consisting of D-l and D-2 polypeptides and cytochrome b-559. Proc. Natl. Acad. Sci., 84 109-112. 

Satoh, K. (1996). Introduction to photosystem II reaction center Isolation and biochemical and biophysical characterization. In D.R. Qrt and C.F. Yocum, eds., Oxygenic Photosynthesis. Boston Kluwer, pp. 193-212. 

Sobolev, V. and M. Edelman (1995). Modeling the quinone-B binding site of the photosystem II reaction center using notions of complementarity and contact-surface between atoms. Prot. Struct., Fund. Genet., 21 214—225. 

Xiong, J., S. Subramaniam, and Govindjee (1998). A knowledge-based three dimensional model of the photosystem II reaction center of Chlamydomonas reinhartdtii. Photosyn. Res., 56 229-254. 

Trebst, A., B. Depka, B. Kraft, and U. Johanningmeier (1988). The QB-site modulates the conformation of the photosystem II reaction center polypeptides. Photosynthesis Res., 18 163-177. 

Sharma, J. Panico, M. Barber, J. Morris, H. R. 1997. Purification and determination of intact molecular mass by electrospray ionization mass spectrometry of the photosystem II reaction center subunits. J. Biol. Chem., 272,33153-33157. 

PHOTOSYSTEM-II REACTION CENTER COUPLING WITH THE ANTENNA... 

Frank, H.A., Hansson, O. and Mathis, P. 1987. Low temperature ESR and absorption spectroscopy of the Photosystem II reaction center complex (submitted). 

Michel, H. and Deisenhofer J. 1986. X-ray diffraction studies on a crystalline bacterial photosynthetic reaction center a progress report and conclusions on the structure of photosystem II reaction centers. In Encyclopedia of Plant Physiol., new series) (Eds. L.A.Staehelin and Amtzen) (Springer, Berlin). Vol. 19, 371-381. 

Olive, J., Wollman, F.A., Bennoun, P. and Recouvreur, M. 1979. Ultrastruct-ure—function relationship in Chlamydomonas reinhardtii thylakoids, by means of a comparison between the wild type and the F34 mutant which lack the photosystem II reaction center. Molec. Biol. Rep. 5,139-143. 

Yamagishi, A. and Katoh S. 1985. Further characterization of two photosystem II reaction center complex preparations from the thermophilic cyanobacterium Synechococcus sp. Biochim. Biophys. Acta 807. 74-80. 

Evance, M.C.W., Rich, A.M., and Nugent, J.H.A. (2000) Evidence for the presence of a component of the Mn complex of the Photosystem II reaction center which is exposed to water in the S2 state of the water oxidation complex, FEBS Letters, All, 113-117. 

Herbicides that inhibit photosynthetic electron flow prevent reduction of plastoquinone by the photosystem II acceptor complex. The properties of the photosystem II herbicide receptor proteins have been investigated by binding and displacement studies with radiolabeled herbicides. The herbicide receptor proteins have been identified with herbicide-derived photoaffinity labels. Herbicides, similar in their mode of action to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) bind to a 34 kDa protein, whereas phenolic herbicides bind to the 43-51 kDa photosystem II reaction center proteins. At these receptor proteins, plastoquinone/herbicide interactions and plastoquinone binding sites have been studied, the latter by means of a plastoquinone-deriv-ed photoaffinity label. For the 34 kDa herbicide binding protein, whose amino acid sequence is known, herbicide and plastoquinone binding are discussed at the molecular level. 

The phenolic photoaffinity label azidodinoseb (Figure 4) binds less specifically than either azidoatrazine or azidotriazinone (14). In addition to other proteins, it labels predominantly the photosystem II reaction center proteins (spinach 43 and 47 kDa Chlamydomo-nas 47 and 51 kDa) (17). Because of the unspecific binding of azidodinoseb, this can best be seen in photosystem II preparations (17). Thus, the phenolic herbicides bind predominantly to the photosystem II reaction center, which might explain many of the differences observed between "DCMU-type" and phenolic herbicides (9). The photosystem II reaction center proteins and the 34 kDa herbicide binding protein must be located closely to and interact with each other in order to explain the mutual displacement of both types of herbicides (8,12,21). Furthermore, it should be noted that for phenolic herbicides, some effects at the donor side of photosystem II (22) and on carotenoid oxidation in the photosystem II reaction center have been found (23). 

Photosystem II reaction center from oxygen-evolving photosynthetic organisms that oxidizes water and reduces plastoquinone... 

Five of the eight subunits of photosystem II reaction center are synthesized on chloroplast ribosomes. The three Tris-soluble subunits are synthesized on cytoplasmic ribosomes as larger precursors and are transported into the chloroplast by a vectorial processing mechanism [29, 119-121,133]. The genes coding for all the... 

Fig. 12.1. Relative sizes of mitochondrial and chloroplast chromosomes and location of protein structural genes. The figure was constructed from published data [5,15,17,22,26-28]. The structural genes are marked by wide sections. Black areas code for proteins. White areas are introns. 0x1, OxII and OxIII are subunits I, II and III of cytochrome c oxidase. Cyt b, cytochrome b. Fo and Fo, are subunits 6 and 9 of the proton ATPase complex. In the chloroplast chromosome the arrows indicate the transcription direction and the size of the transcripts. CF,a, CFj/8, CFjc and CFoIII are subunits a, /S, t and III of the chloroplast proton ATPase complex [30]. PSII5], PSII44, and PSII34 are subunits of photosystem II reaction center with the corresponding molecular weights of 51000, 44000 and 34000. PSI70 is subunit I of photosystem I reaction center. Cyt /is cytochrome/ cyt is cytochrome b and b -flV is subunit IV of cytochrome b(,-f complex.

As shown in both Fig. 21 (A) and (B), there are five major protein complexes in the thylakoid-mem-brane network (1) the photosystem-11 core with bound inner antennae (collectively designated as PS II ), (2) the photosystem-I core with bound anteimae LHC I (collectively designated as PS I ), (3) the cytochrome (jg/complex, (4) theCFo CF, ATP-synthase and, finally (5) a separate, peripheral lightharvesting, chlorophyll-protein complex called LHC 11 that supplements the inner antennae bound to the photosystem-II reaction center. ... 

J Xiong, S Subramaniam and Govindjee (1996) Modeling of the D1/D2 proteins and cofactors ofthe photosystem II reaction center. Implications for herbicide and bicarbonate binding. Protein Sci 5 2054-2073 FI Michel and J Deisenhofer (1988) Relevance ofthe photosynthetic reaction centers from purple bacteria to the structure of photosystem II. Biochemistry 27 1-7... 

BA Diner and V Petrouleas (1990) Formation of NO ofnitrosyl adducts of redox components ofthe photosystem II reaction center. II. Evidence that FICD3YCD2 b/nds to the acceptor-side non-heme iron. Biochim Biophys Acta 1015 141-149... 

H Fujiwara, H Hayashi, M Tasumi, M Kanji, YKoyamaand (Ki) Satoh (1987) Structural studies on a photosystem II reaction center complex consisting ofD-1 and D-2 polypeptides and cytochrome b-559 by resonance Raman spectroscopy and high-performance liquid chromatography. Chem Lett 10 2005-2008 GE Bialek-Bylka, T Tomo, (Ki) Satoh and Y Koyama (1995) 15-cis-carotene found in the reaction center of spinach photosystem II. FEES Lett 363 137-140... 

Fig. 4. (A) EPR spectra of TSF lla particles poised at -450 mV and after 90-s illumination at 295 or 220 K and measured at two different microwave powers. (B) shows effect of microwave power (P) on the amplitude of the photoinduced narrow (singlet) and doublet EPR signals at 7 K, Figure source Klimov, Dolan and Ke (1980) EPR properties of an intermediary electron acceptor (pheophytin) in photosystem II reaction centers at cryogenic temperatures. FEBS Lett 112 98,99 and Klimov, Dolan, Shaw and Ke (1980) Interaction between the intermediary electron acceptor (pheophytin) and a possible plastoquinone-lron complex in photosystem-ll reaction centers. Proc Nat Acad Sci, USA. 77 7228...

The transient intermediary electron acceptor, reaction center is expected to be reduced very rapidly following a flash, perhaps on the order of picoseconds. Not surprisingly, its belated discovery in 1979 did not come about through rapid kinetic measurements, but rather by way of the rather slow process of photo-accumulation under conditions in which the secondary electron acceptor Qa is kept in its reduced state by electrochemical manipulation. After much of the chemical and physical properties ofO had become known, the question of its photoreduction rate naturally became of interest. 

Fig. 8. (A) Transient absorption-change spectrum of PS-II reaction-centers 10 ps after excitation with a 500-fs, 610-nm flash. (B) Kinetics of transient absorbance changes at 820 and 674 nm from PS-II reaction centers after excitation with 500-fs, 610-nm flashes. Figures ource Wasielewski, Johnson, Seibert and Govindjee (1989) Determination of the primary charge separation rate in isolated photosystem II reaction centers with 500-fs time resolution. Proc Nat Acad Sci, USA 86 525-526.

Fig. 9. Transient absorption spectra of isolated PS-II reaction-center complex at 7 K recorded at various time delays between 0.5 ps and 2.0 ns after a 100-nJ, 683-nm (A) or661-nm (B) excitation pulse. Monitoring wavelengths 543.5 and 558.5 nm used for the bleach-growth analysis (not shown) are marked with thin, dashed lines. Figure source Greenfield, Seibert and Wasielewski (1999) Time-resolved absorption changes of the pheophytin Qx band in isolated photosystem II reaction centers at 7 K Energy transfer and charge separation. J Phys Chem 103 8364-8374.

In DR Ort and CF Yocum (eds) Oxygenic Photosynthesis. The Light Reactions, pp 213-247. Kluwer R2. M Seibert (1993) Biochemical, biophysical, and structural characterization of the isolated photosystem II reaction center complex. In J Deisenhofer and JR Norris (eds) The photosynthetic Reaction Center, vol 1 319-356 R3. WW Parson and B Ke (1982) Primary photochemical reactions. In Govindjee (ed) Photosynthesis Energy Conversion by Plants and Bacteria, Vol 1, pp 331-385. Acad Press R4. VV Klimov and AA Krasnovsky (1981) Pheophytin as the primary electron acceptor in photosystem 2 reaction centres. Photosynthetica 15 592-609... 

VV Klimov, E Dolan and B Ke (1980) EPR properties of an intermediary electron acceptor (pheophytin) in photosystem II reaction centers at cryogenic temperatures. FEBS Lett 112 97-100... 

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