Crystal structure of photosystem II from Synechococcus elongatus at 3.8 Å resolution

Zouni, Athina; Witt, H. T.; Kern, Jan; Fromme, Petra; Krauß, Norbert; Saenger, Wolfram; Orth, Peter

doi:10.1038/35055589

Cited by 1,972 publications

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“…This observation is consistent with the estimated 10 Å center to center distance between the metal centers of these chlorophylls from electron and X-ray diffraction studies of PSII crystals (17,18,73) as opposed to the 7.6 Å found in bacterial reaction centers (3)(4)(5).…”

Section: Location Of 3 P As a Function Of Temperaturesupporting

confidence: 88%

Site-Directed Mutations at D1-His198 and D2-His197 of Photosystem II in Synechocystis PCC 6803: Sites of Primary Charge Separation and Cation and Triplet Stabilization

et al. 2001

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Site-directed mutations were introduced to replace D1-His198 and D2-His197 of the D1 and D2 polypeptides, respectively, of the photosystem II (PSII) reaction center of Synechocystis PCC 6803. These residues coordinate chlorophylls P A and P B which are homologous to the special pair Bchlorophylls of the bacterial reaction centers that are coordinated respectively by histidines L-173 and M-200 (202). P A and P B together serve as the primary electron donor, P, in purple bacterial reaction centers. In PS II, the site-directed mutations at D1 His198 affect the P + -P-absorbance difference spectrum. The bleaching maximum in the Soret region (in WT at 433 nm) is blue-shifted by as much as 3 nm. In the D1 His198Gln mutant, a similar displacement to the blue is observed for the bleaching maximum in the Q y region (672.5 nm in WT at 80 K), whereas features attributed to a band shift centered at 681 nm are not altered. In the Y Z •-Y Z -difference spectrum, the band shift of a reaction center chlorophyll centered in WT at 433-434 nm is shifted by 2-3 nm to the blue in the D1-His198Gln mutant. The D1-His198Gln mutation has little effect on the optical difference spectrum, 3 P-1 P, of the reaction center triplet formed by P + Pheo -charge recombination (bleaching at 681-684 nm), measured at 5-80 K, but becomes visible as a pronounced shoulder at 669 nm at temperatures g150 K. Measurements of the kinetics of oxidized donor-Q A -charge recombination and of the reduction of P + by redox active tyrosine, Y Z , indicate that the reduction potential of the redox couple P + /P can be appreciably modulated both positively and negatively by ligand replacement at D1-198 but somewhat less so at D2-197. On the basis of these observations and others in the literature, we propose that the monomeric accessory chlorophyll, B A , is a long-wavelength trap located at 684 nm at 5 K. B A * initiates primary charge separation at low temperature, a function that is increasingly shared with P A * in an activated process as the temperature rises. Charge separation from B A * would be potentially very fast and form P A + B A -and/or B A + Pheo -as observed in bacterial reaction centers upon direct excitation of B A ) Proc. Natl. Acad Sci. 96, 2054-2059. The cation, generated upon primary charge separation in PSII, is stabilized at all temperatures primarily on P A , the absorbance spectrum of which is displaced to the blue by the mutations. In WT, the cation is proposed to be shared to a minor extent (∼20%) with P B , the contribution of which can be modulated up or down by mutation. The band shift at 681 nm, observed in the P + -P difference spectrum, is attributed to an electrochromic effect of P A + on neighboring B A . Because of its low-energy singlet and therefore triplet state, the reaction center triplet state is stabilized on B A at e80 K but can be shared with P A at >80 K in a thermally activated process.

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Section: Location Of 3 P As a Function Of Temperaturesupporting

confidence: 88%

Site-Directed Mutations at D1-His198 and D2-His197 of Photosystem II in Synechocystis PCC 6803: Sites of Primary Charge Separation and Cation and Triplet Stabilization

et al. 2001

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“…In this way, excitation energy migrates from the peripheral antenna, via minor light-harvesting chlorophyll-protein complexes, towards the inner antenna surrounding the reaction centre. In the inner antenna of PS II, chlorophyll a molecules are also held in a scaffold with centre-to-centre distance of 8.5-13.5 Å as determined by X-ray crystallography [8]. This range of distances is the same as that (9-14 Å) in the peripheral antenna determined by electron crystallography [7].…”

Section: Excitation Energy Transfermentioning

confidence: 76%

Photosynthesis: From Natural Towards Artificial

Chow

2003

Journal of Biological Physics

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Abstract. Photosynthesis, the natural process that yields food, fuel and fibre, spans physical and biological sciences, spatially from atomic scales to the global and temporally from electronic transitions to the evolutionary time frame. Photosynthesis is highly efficient in its primary energy capture, but much less so in terms of conversion to crop yield. The natural photosynthetic system provides fertile ground for exploring and dissecting partial processes that may be mimicked in artificial systems for human needs, perhaps with improved efficiency. Future developments are limited only by the imagination.

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“…The high to low potential −300 mV transition of the cytochrome midpoint potential, from high to low potential, caused by heat or trypsin treatment was attributed to membrane damage and loss of the local hydrophobic niche (Krishtalik et al 1993), and perhaps a contribution from changes in orientation of the orthogonal histidine ligands (Babcock et al 1985). (vi) The α-β heterodimeric structure and stromal side location of the heme of Cyt b-559 in the PS II reaction center has been confirmed in the crystal structure determination of the reaction center dimer purified from cyanobacteria to a resolution of 3.7-3.8 Å (Zouni et al 2001;Kamiya and Shen 2003), although the orientation of the histidine side chains of the cytochrome cannot be determined at this resolution. The X-ray structure showing one stromal-side heme appears to have settled any question about the heterodimeric nature of Cyt b-559.…”

Section: Structure-function Of Cytochrome B-559mentioning

confidence: 91%

“…The oxidation was blocked by the quinol analogue inhibitor, 3-(3,4-dichlorophenyl)-1,1-(dimethylurea) (DCMU) (Horton and Cramer 1975;Horton et al 1976). If I had known the distances of separation between Cyt b-559 and its closest redox partners, approximately 28 Å centercenter between Q B and the b-559 heme, and 27 Å between the heme and chlorophyll Z (on D2 protein), which were shown in the crystal structure of PS II (Zouni et al 2001), I would not have felt so badly at that time about Bessel's comment. The present structure data show that the redox reactions between the Q B acceptor of PS II and Cyt b-559 cannot be very fast.…”

Section: Structure-function Of Cytochrome B-559mentioning

confidence: 99%

“…The implication of the latter studies is that the Cyt b-559 might participate in reactions of water splitting. However, the stromal side location of the Cyt b-559 heme (Zouni et al 2001) is on the wrong side of the membrane to participate in this pathway. One other function that could correlate with the presence of O 2 evolution is a role of Cyt b-559 as an intra-membrane oxygen transporter.…”

Section: Other Suggestions For the Function Of Cytochrome B-559mentioning

confidence: 99%

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Ironies in Photosynthetic Electron Transport: A Personal Perspective

Cramer

2004

Photosynthesis Research

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In this brief personal perspective, studies, mainly in my laboratory, directed toward understanding of the structure and function of the Fe-metalloprotein electron transport carriers of oxygenic photosynthesis are discussed. This level of understanding and the description of the events that led to this level are inevitably incomplete. The Fe-proteins considered are those, cytochromes b-559 (560), f, b 6 , and x, and the Rieske [2Fe-2S] iron-sulfur protein, which have now been placed in a structural context as a result of X-ray diffraction analysis of crystals of Photosystem II and the cytochrome b 6 f complex and the Photosystem II reaction center.Abbreviations: Cyt -cytochrome; DBMIB -2,5 dibromo 3-methyl 6-isopropyl p-benzoquinone; DCMU -3-(3,4-dichlorophenyl)-1,1-(dimethylurea); E m -midpoint oxidation-reduction potential; EPR -electron paramagnetic resonance; FCCP -carbonyl cyanide-p-trifluoromethoxy-phenylhydrazone; FNR -ferredoxin:NADP + reductase; His -histidine; HP and LP -high and low potential; HPLC -high performance liquid chromatography; nmnanometer; PS -photosystem; SDS-PAGE; sodium dodecyl sulfate-polyacrylamide gel electrophoresis

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Crystal structure of photosystem II from Synechococcus elongatus at 3.8 Å resolution

Cited by 1,972 publications

References 28 publications

Site-Directed Mutations at D1-His198 and D2-His197 of Photosystem II in Synechocystis PCC 6803: Sites of Primary Charge Separation and Cation and Triplet Stabilization

Site-Directed Mutations at D1-His198 and D2-His197 of Photosystem II in Synechocystis PCC 6803: Sites of Primary Charge Separation and Cation and Triplet Stabilization

Photosynthesis: From Natural Towards Artificial

Ironies in Photosynthetic Electron Transport: A Personal Perspective

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