Functional architecture of higher plant photosystem II supercomplexes. EMBO J

Faculté des Sciences Luminy, Laboratoire de Génétique et Biophysique des Plantes, Université Aix Marseille, Marseille, France.
The EMBO Journal (Impact Factor: 10.43). 09/2009; 28(19):3052-63. DOI: 10.1038/emboj.2009.232
Source: PubMed


Photosystem II (PSII) is a large multiprotein complex, which catalyses water splitting and plastoquinone reduction necessary to transform sunlight into chemical energy. Detailed functional and structural studies of the complex from higher plants have been hampered by the impossibility to purify it to homogeneity. In this work, homogeneous preparations ranging from a newly identified particle composed by a monomeric core and antenna proteins to the largest C(2)S(2)M(2) supercomplex were isolated. Characterization by biochemical methods and single particle electron microscopy allowed to relate for the first time the supramolecular organization to the protein content. A projection map of C(2)S(2)M(2) at 12 A resolution was obtained, which allowed determining the location and the orientation of the antenna proteins. Comparison of the supercomplexes obtained from WT and Lhcb-deficient plants reveals the importance of the individual subunits for the supramolecular organization. The functional implications of these findings are discussed and allow redefining previous suggestions on PSII energy transfer, assembly, photoinhibition, state transition and non-photochemical quenching.

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Available from: Roberta Croce,
    • "The structures of a number of assembly factors for PS II including Psb27 [25], Psb28 [26], Ycf48 [27] and Psb31 [28] have been solved using these methods. Single particle imaging (and cryoelectron microscopy) has also contributed significantly to our understanding of photosynthetic supercomplexes such as the PS II- LHC II [29] [30] [31] [32] [33], PS I-LHCII [34], the PS II-phycobilisome [35] and PS Iphycobilisome [36] [37] interactions. Atomic force microscopy is also a developing technique which may be useful in this regard [38] [39] [40]. "
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    ABSTRACT: Tandem mass spectrometry often coupled with chemical modification techniques, is developing into increasingly important tool in structural biology. These methods can provide important supplementary information concerning the structural organization and subunit make-up of membrane protein complexes, identification of conformational changes occurring during enzymatic reactions, identification of the location of posttranslational modifications, and elucidation of the structure of assembly and repair complexes. In this review, we will present a brief introduction to Photosystem II, tandem mass spectrometry and protein modification techniques that have been used to examine the photosystem. We will then discuss a number of recent case studies that have used these techniques to address open questions concerning PS II. These include the nature of subunit-subunit interactions within the phycobilisome, the interaction of phycobilisomes with Photosystem I and the Orange Carotenoid Protein, the location of CyanoQ, PsbQ and PsbP within Photosystem II, and the identification of phosphorylation and oxidative modification sites within the photosystem. Finally, we will discuss some of the future prospects for the use of these methods in examining other open questions in PS II structural biochemistry.
    Journal of photochemistry and photobiology. B, Biology 09/2015; DOI:10.1016/j.jphotobiol.2015.08.031 · 2.96 Impact Factor
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    • "Mass spectrometric analyses of isolated C 2 S 2 M 2 PSII supercomplexes revealed the presence of extrinsic subunits PSBP, PSBQ, and PSBR, while PSBS was not identified, suggesting that PSBS does not influence the association of the PSII core with the outer light-harvesting complex system (Pagliano et al., 2014). In line with the proteomic findings, recent data suggest that subunits PSBP, PSBQ, and PSBR contribute to the stability of PSII-LHCII supercomplexes in vascular plants (Caffarri et al., 2009; Ifuku et al., 2011; Allahverdiyeva et al., 2013). A recent quantitative proteomic study performed with C. reinhardtii identified PSBR as the only PSII subunit to be induced upon the shift from photoheterotrophic to photoautotrophic growth conditions similar to LHCSR3 (Höhner et al., 2013). "
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    ABSTRACT: In Chlamydomonas reinhardtii the LHCSR3 protein is crucial for efficient energy-dependent thermal dissipation of excess absorbed light energy and functionally associates with PSII-LHCII supercomplexes. Currently, it is unknown of how LHCSR3 binds to the PSII-LHCII supercomplex. In this study we investigated the role of PSBR, an intrinsic membrane-spanning PSII subunit, in binding of LHCSR3 to PSII-LHCII supercomplexes. Down regulation of PSBR expression diminished the efficiency of oxygen evolution and the extent of non-photochemical quenching (NPQ) and had an impact on the stability of the oxygen-evolving complex as well as on PSII-LHCII-LHCSR3 supercomplex formation. Its down regulation destabilized the PSII-LHCII supercomplex and strongly reduced binding of LHCSR3 to PSII-LHCII supercomplexes as revealed by quantitative proteomics. PSBP deletion on the contrary destabilized PSBQ binding but did not affect PSBR and LHCSR3 association with PSII-LHCII. In summary, the data provide clear evidence that PSBR is required for stable binding of LHCSR3 to PSII-LHCII supercomplexes, essential for efficient qE quenching, and integrity of the PSII-LHCII-LHCSR3 supercomplex under continuous high light. Copyright © 2015, Plant Physiology.
    Plant physiology 02/2015; 167(4). DOI:10.1104/pp.15.00094 · 6.84 Impact Factor
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    • "We aim to investigate the long-range transport of excitation energy in the Photosystem II supercomplex, from the surrounding antenna complexes, through the outer components of the supercomplex, to the reaction center – by means of a full quantum simulation. To this end, we model a subsection of the Photosystem II supercomplex originally isolated by Croce, et al. [24] and subsequently used as a foundation for a structure based excitation energy transport model to explain the measured fluorescence lifetimes [2]. Figure 1 shows the largest PSII supercomplex previously modeled [2] [16]. The colored pigments in LHCII, CP43, and the reaction center shown in Figure 1 represent the subsystem that we model in this work: it contains 33 chromophores distributed between a LHCII monomer (14 pigments), CP43 (13 pigments), and a truncated reation center (6 pigments). "
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    ABSTRACT: We simulate the long-range inter-complex electronic energy transfer in Photosystem II -- from the antenna complex, via a core complex, to the reaction center -- using a non-Markovian (ZOFE) quantum master equation description that allows us to quantify the electronic coherence involved in the energy transfer. We identify the pathways of the energy transfer in the network of coupled chromophores, using a description based on excitation probability currents. We investigate how the energy transfer depends on the initial excitation -- localized, coherent initial excitation versus delocalized, incoherent initial excitation -- and find that the energy transfer is remarkably robust with respect to such strong variations of the initial condition. To explore the importance of vibrationally enhanced transfer and to address the question of optimization in the system parameters, we vary the strength of the coupling between the electronic and the vibrational degrees of freedom. We find that the original parameters lie in a (broad) region that enables optimal transfer efficiency, and that the energy transfer appears to be very robust with respect to variations in the vibronic coupling. Nevertheless, vibrationally enhanced transfer appears to be crucial to obtain a high transfer efficiency. We compare our quantum simulation to a "classical" rate equation based on a modified-Redfield/generalized-F\"orster description that was previously used to simulate energy transfer dynamics in the entire Photosystem II complex, and find very good agreement between quantum and rate-equation simulation of the overall energy transfer dynamics.
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