Photosystem II reaction center protein

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). 

Comparison of aligned sequences in the PEST-1ike region of the 32kDa photosystem II reaction center protein with those of L subunit of Rhodopseudomonas capsulata (Lc). Adapted from ref. 38. 

Elich TE, Edelman M, Mattoo AK. Identification, characterization, and resolution of the in vivo phosphorylated form of the D1 photosystem II reaction center protein. J Biol Chem 1992 ... 

Kettunen R, Tyystjarvi E, Aro E-M. Degradation pattern of photosystem II reaction center protein D1 in intact leaves. Plant Physiol 1996 111 1183-1190. 

Clarke AK, Soitamo A, Gustafsson P et al. Rapid interchange between two distinct forms of cyanobacterial photosystem II reaction center protein D1 in response to photoinhibidon. Proc Nad Acad Sci USA 1993 90 9973-9977. 

Sopory SK, Greenberg BM, Mehta RA et al. Fr radical scavengers inhibit light-dependent d ada-don of the 32 kDa Photosystem II reaction center protein. Z Naturfbrs C-A Journal of Biosciences 1990 45 412-417. 

Mattoo A, Giardi MT, Raskind A et al. Dynamic metabolism of photosystem II reaction center proteins and pigments. A review. Physiol Plant 1999 107 454-461. 

The irreversibly binding [ H]2-acetoxymethyl-1,4-naphthoquinone was reported to label two polypeptides with apparent molecular weights of 38 and 19 kDa. It was suggested that the labelled 38 kDa protein is the D-2 photosystem II reaction center protein (5). 

The reaction-center proteins for Photosystems I and II are labeled I and II, respectively. Key Z, the watersplitting enzyme which contains Mn P680 and Qu the primary donor and acceptor species in the reaction-center protein of Photosystem II Qi and Qt, probably plastoquinone molecules PQ, 6-8 plastoquinone molecules that mediate electron and proton transfer across the membrane from outside to inside Fe-S (an iron-sulfur protein), cytochrome f, and PC (plastocyanin), electron carrier proteins between Photosystems II and I P700 and Au the primary donor and acceptor species of the Photosystem I reaction-center protein At, Fe-S a and FeSB, membrane-bound secondary acceptors which are probably Fe-S centers Fd, soluble ferredoxin Fe-S protein and fp, is the flavoprotein that functions as the enzyme that carries out the reduction of NADP+ to NADPH. 

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... 

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... 

In addition, the recent demonstration of the 32kDa protein as an essential component of the higher plant photosystem II reaction center (6,7) has added a new dimension to this interest with still broader implications for crop improvement in agriculture. 

Precursor Processing. Hie precursor protein is synthesized on stromal lamellae and is processed there to the 32kDa mature form (21). Processing of the precursor is a posttranslational event (12) and takes place at the carboxy terminus (22). Following processing, the mature protein translocates to spatially-distinct chloroplast membranes, the grana, where functional photosystem II reaction centers are mainly located (21, 23). 

Fig. 12. A diagrammatic model ofthe arrangement oftwo carotenes (labeled as carotenoid 489 and carotenoid 507) in the reaction center molecLde of PS II. P680is the reaction center Chi a dimer, whereas D1 and D2 are the two proteins where the chromophores are housed. The scheme shown here was modified and adapted from Mimuro et al. (1995). For a more complete model of Photosystem II reaction center and a different view of the arrangement of carotenoids, see Xiong etal. (1998).

The primary events of photosystem I have not yet been elucidated. Preliminary results indicate that the photochemistry occurs on the picosecond time scale. There is also some evidence to indicate that the primary electron acceptor may be a chlorophyll complex. Spectral changes associated with a number of intermediate acceptors have also been observed. Some of these acceptors have been identified as iron-sulfur proteins. Photosystem II reaction centers have a photoactive form of chlorophyll that absorbs at 680 nm. While very little else is known about the photoactive form in photosystem II, a great deal of information is available on the electron donors and acceptors of photosystem II. 

Ghanotakis DF, Demetriou DM, Yocum CF. Isolation and characterization of an 02-evolving Photosystem II reaction center core preparation and a 28 kDa chi -binding protein Biochim Biophys Acta 1987 891 15-21. 

Ikeuchi M, Inoue Y. A new 38 kDa polypeptide intrinsic to Photosystem II reaction center as revealed by modified SDS-PAGE with improved resolution of the low-molecular-weight proteins. Plant Cell Physiol 1988 29 1233-1239. 

Leuschner C, Bricker TM. Interaction of the 33 kDa extrinsic protein with photosystem II Rebinding of the 33 kDa extrinsic protein to photosystem II membranes that contain four, two or zero manganese per photosystem II reaction center. Biochemistry 1996 35 4551-4557. 

Hutchison RS, Betts SD> Yocum CF et al. Conformational changes in the extrinsic manganese stabilizing protein can occur upon binding to the photosystem II reaction center an isotope editing and FTIR study. Biochemistry 1998 37 5643-5653. 

Plucken HB, Muller B, Gtohmann D et al. The HCF136 protein is essential for assembly of the photosystem II reaction center in Arabidopsis thaliana. FEBS Lett 2002 532 85-90. 

He WZ, Newell WR, Haris PI et al. Protein secondary struaure of the isolated photosystem II reaction center and conformational changes studies by Fourier transform infrared spectroscopy. Biochemistry 1991 30 4552-4559. 

Barbato R, Friso G, Ponricos M et al. Characterizadon of the light-induced cross-linking of the a-subunit of cytochrome b-559 and the D1 protein in isolated photosystem II reaction centers. J Biol Chem 1995 270 24032-24037. 

Sobolev V, Edelman M. Modeling of the quinone-B binding site of the photosystem II reaction center using notions of complementarity and contact surface between atoms. Proteins 1995 21 214-225. 

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