Two-dimensional structure of plant photosystem II at 8-Å resolution

Rhee, Kyong−Hi; Morris, Edward P.; Zheleva, Daniela G; Hankamer, Ben; Kühlbrandt, Werner; Barber, James

doi:10.1038/39103

Cited by 152 publications

(109 citation statements)

References 15 publications

(8 reference statements)

Supporting

Mentioning

104

Contrasting

Unclassified

Order By: Relevance

“…There is much more freedom for protein-to-protein interactions and conformational changes in vitro than there are in vivo, where the LHCII components are organized in a strict stoichiometry in the PSII complex Rhee et al, 1997). Thus, in vivo, interaction between CP26 complexes probably could not occur, but interaction of CP26 with different complexes could.…”

Section: Discussionmentioning

confidence: 99%

The Xanthophyll Cycle Modulates the Kinetics of Nonphotochemical Energy Dissipation in Isolated Light-Harvesting Complexes, Intact Chloroplasts, and Leaves of Spinach1

1999

View full text Add to dashboard Cite

We analyzed the kinetics of nonphotochemical quenching of chlorophyll fluorescence (qN) in spinach (Spinacia oleracea) leaves, chloroplasts, and purified light-harvesting complexes. The characteristic biphasic pattern of fluorescence quenching in dark-adapted leaves, which was removed by preillumination, was evidence of light activation of qN, a process correlated with the de-epoxidation state of the xanthophyll cycle carotenoids. Chloroplasts isolated from dark-adapted and light-activated leaves confirmed the nature of light activation: faster and greater quenching at a subsaturating transthylakoid pH gradient. The light-harvesting chlorophyll a/bbinding complexes of photosystem II were isolated from darkadapted and light-activated leaves. When isolated from lightactivated leaves, these complexes showed an increase in the rate of quenching in vitro compared with samples prepared from darkadapted leaves. In all cases, the quenching kinetics were fitted to a single component hyperbolic function. For leaves, chloroplasts, and light-harvesting complexes, the presence of zeaxanthin was associated with an increased rate constant for the induction of quenching. We discuss the significance of these observations in terms of the mechanism and control of qN.Under different physiological conditions the efficiency with which absorbed light energy is harvested by photosynthesis is altered by the operation of a regulatory mechanism that determines how much excitation energy is used and how much is dissipated as heat (Horton, 1987; Demmig-Adams and Adams, 1992;Horton and Ruban, 1992; Bjö rkman and Demmig-Adams, 1995; DemmigAdams et al., 1995). The function of this mechanism is to harmlessly dissipate excess energy when photosynthesis is light saturated, thereby protecting the pigments and proteins of the chloroplast membrane from photo damage. The extent of energy dissipation, measured by the quenching of chlorophyll fluorescence, has been found to correlate with the extent of de-epoxidation of the xanthophyll cycle carotenoids (Demmig-Adams, 1990).The kinetics of the formation and relaxation of quenching and the effects of inhibitors established the role of the energization of thylakoid by the ⌬pH, so this quenching was referred to as qE (Briantais et al., 1979). It is therefore widely accepted that these two factors control the induction of qE . Various reports suggest that qE occurs in LHCII Horton et al., 1996), where the xanthophyll cycle carotenoids are bound (Peter and Thornber, 1991; Bassi et al., 1993;Ruban et al., 1994b) and where proton-active sites involved in qE have been identified Pesaresi et al., 1997). It has been suggested that CP26 and CP29, two of the minor components of LHCII, have a major role in qE Bassi et al., 1993; Crofts and Yerkes, 1994;Walters et al., 1994;Pesaresi et al., 1997;Gilmore et al., 1996b).It is unclear how the xanthophyll cycle and qE are related. Some have suggested that the de-epoxidized pigments antheraxanthin and zeaxanthin directly quench excited chlorophyll singlet states (Demmi...

show abstract

Section: Discussionmentioning

confidence: 99%

The Xanthophyll Cycle Modulates the Kinetics of Nonphotochemical Energy Dissipation in Isolated Light-Harvesting Complexes, Intact Chloroplasts, and Leaves of Spinach1

1999

View full text Add to dashboard Cite

show abstract

“…It had been shown by electron microscopy (EM) that the PSIIRC core complex of plants and cyanobacteria is dimeric (reviewed in Hankamer et al 1997). In fact, our early EM studies employing both electron crystallography (Rhee et al 1997(Rhee et al , 1998Hankamer et al 1999Hankamer et al , 2001) and single particle analyses (Nield et al 2000a(Nield et al ,b, 2002 had also revealed the relative positions of the D1, D2, CP43 and CP47 proteins within each monomer of the dimeric PSII RC core complex isolated from higher plants (spinach) and suggested how their transmembrane helices were arranged (Barber 2002). The best resolution obtained was 8 Å and thus densities could be tentatively assigned to Chls bound within the CP47 protein as well as those that were contained within the D1/D2 heterodimer (Rhee et al 1998).…”

Section: The Structure Of Psii and Its Oecmentioning

confidence: 99%

Photosynthetic generation of oxygen

Barber

2008

Phil. Trans. R. Soc. B

Self Cite

View full text Add to dashboard Cite

The oxygen in the atmosphere is derived from light-driven oxidation of water at a catalytic centre contained within a multi-subunit enzyme known as photosystem II (PSII). PSII is located in the photosynthetic membranes of plants, algae and cyanobacteria and its oxygen-evolving centre (OEC) consists of four manganese ions and a calcium ion surrounded by a highly conserved protein environment. Recently, the structure of PSII was elucidated by X-ray crystallography thus revealing details of the molecular architecture of the OEC. This structural information, coupled with an extensive knowledge base derived from a wide range of biophysical, biochemical and molecular biological studies, has provided a framework for understanding the chemistry of photosynthetic oxygen generation as well as opening up debate about its evolutionary origin.

show abstract

“…However, studies of the structure of PSII have appeared only in recent years. The 3D image of PSII was first studied by electron cryomicroscopy of 2D crystals of various PSII particles, and a structure at 8-Å resolution has been reported for a CP47-RC-PSII complex, which lacked oxygen-evolving activity, and its related three extrinsic proteins (4,5). Recently, 3D crystals have been obtained for oxygen-evolving PSII complexes from two species of thermophilic cyanobacteria (6)(7)(8), and the PSII crystal structure from one of such cyanobacterium, Thermosynechococcus elongatus (formerly Synechococcus elongatus), was reported at 3.8-Å resolution by Zouni et al (9).…”

mentioning

confidence: 99%

Crystal structure of oxygen-evolving photosystem II from Thermosynechococcus vulcanus at 3.7-Å resolution

Kamiya

Shen

2002

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

1,101

840

View full text Add to dashboard Cite

To analyze the PSII structure in more detail, we have obtained the crystal structure of PSII from another thermophilic cyanobacterium, Thermosynechococcus vulcanus, at 3.7-Å resolution. The present structure was built on the basis of the sequences of PSII large subunits D1, D2, CP47, and CP43; extrinsic 33-and 12-kDa proteins and cytochrome c550; and several low molecular mass subunits, among which the structure of the 12-kDa protein was not reported previously. This yielded much information concerning the molecular interactions within this large protein complex. We also show the arrangement of chlorophylls and cofactors, including two ␤-carotenes recently identified in a region close to the reaction center, which provided important clues to the secondary electron transfer pathways around the reaction center. Furthermore, possible ligands for the Mn-cluster were determined. In particular, the C terminus of D1 polypeptide was shown to be connected to the Mn cluster directly. The structural information obtained here provides important insights into the mechanism of PSII reactions.T he photosystem II (PSII) complex is a multisubunit membrane-protein complex consisting of Ͼ14 membranespanning subunits, 3 hydrophilic peripheral subunits, and Ͼ40 cofactors, including chlorophylls (chls), carotenoids, Mn, Fe, and plastoquinones, with a total molecular mass of 320 kDa for a monomer (for review, see refs. 1-3). The PSII reaction center (RC) P680 is a (pair of) chl a coordinated by RC D1- and undergoes charge separation on absorption of light energy; the electrons thus generated are transferred to pheophytin, the first quinone acceptor Q A , and then the second quinone acceptor Q B . At the oxidizing side of PSII, a redoxactive tyrosine residue D1-Tyr-161 (Tyr Z ) reduces P680. The oxidized Tyr Z withdraws electrons from a Mn cluster consisting of four Mn atoms, which in turn withdraws electrons in a sequential way from water molecules, leading to the splitting of water and formation of molecular oxygen. This reaction provides us with the oxygen-rich atmospheric environment suitable for most of the organisms to live on the earth, whereas the protons yielded are the source for proton gradient across the thylakoid membrane required for ATP formation.In view of its importance, PSII has received extensive studies in the past several decades regarding its protein composition, function, and dynamic regulation. As a result, our understanding of the function and reaction mechanisms of PSII has increased greatly. However, studies of the structure of PSII have appeared only in recent years. The 3D image of PSII was first studied by electron cryomicroscopy of 2D crystals of various PSII particles, and a structure at 8-Å resolution has been reported for a CP47-RC-PSII complex, which lacked oxygen-evolving activity, and its related three extrinsic proteins (4, 5). Recently, 3D crystals have been obtained for oxygen-evolving PSII complexes from two species of thermophilic cyanobacteria (6-8), and the PSII crystal structure from one of...

show abstract

Two-dimensional structure of plant photosystem II at 8-Å resolution

Cited by 152 publications

References 15 publications

The Xanthophyll Cycle Modulates the Kinetics of Nonphotochemical Energy Dissipation in Isolated Light-Harvesting Complexes, Intact Chloroplasts, and Leaves of Spinach1

The Xanthophyll Cycle Modulates the Kinetics of Nonphotochemical Energy Dissipation in Isolated Light-Harvesting Complexes, Intact Chloroplasts, and Leaves of Spinach1

Photosynthetic generation of oxygen

Crystal structure of oxygen-evolving photosystem II from Thermosynechococcus vulcanus at 3.7-Å resolution

Contact Info

Product

Resources

About