Oxygen-evolving extrinsic proteins (PsbO,P,Q,R): Bioinformatic and functional analysis

Abstract

The water-splitting and oxygen-evolving (OE) reaction is carried out by a large multisubunit protein complex, Photosystem II (PSII), that has two distinct regions: a membrane intrinsic-region that includes most of the PSII subunits and a lumenal extrinsic-region that is in close association to the manganese catalytic center. The recently determined PSII 3D structures from cyanobacteria provide a considerable amount of new knowledge about the OE architecture (K.N. Ferreira, T.M. Iverson, K. Maghlaoui, J. Barber, S. Iwata, Architecture of the photosynthetic oxygen-evolving center, Science 303 (2004) 1831-1838; B. Loll, J. Kern, W. Saenger, A. Zouni, J. Biesiadka, Towards complete cofactor arrangement in the 3.0 A resolution structure of photosystem II, Nature 438 (2005) 1040-1044). Most of the intrinsic core PSII polypeptides have been well conserved through evolution from ancient cyanobacteria to modern plants, keeping the essence of PSII light driven reactions from prokaryotes to eukaryotes; but what is striking is the large number of changes that have occurred in the oxygen-evolving extrinsic proteins (OEEp) associated to PSII lumenal side. For unknown reasons plant PSII has required the "invention" of three OEEps: PsbP (23 kDa), PsbQ (16 kDa) and PsbR (10 kDa); associated to the ubiquitous OEEp PsbO (33 kDa). This set of proteins seems to be required in plants for the full activity and stability of the OE center in vivo, but their specific function is not clear. In this paper, bioinformatics and functional data show that the OEEps present in plants and green algae are very distinct from their prokaryotic counterparts. Moreover, clear differences are found for PsbQ from higher plants and green algae; and a relationship has been found between PsbR and the Mn cluster.

Structural and functional aspects of the MSP (PsbO) and study of its differences in thermophilic versus mesophilic organisms

“…All oxygenic photosynthetic organisms have the 33 kDa MSP subunit. The subunits of PSII, their functions and cofactors have been extensively reviewed in the following references: (Barber 2003(Barber , 2006aDe Las Rivas et al 2007;Nelson and Yocum 2006;Nield and Barber 2006;Wydrzynski and Satoh 2006).…”

“…The structure and function of the MSP has been thoroughly studied to determine its role in oxygen evolution by PSII. A number of reviews about the structure and function of the MSP and the other extrinsic proteins of PSII are available (Bricker and Burnap 2005;Bricker and Frankel 1998;De Las Rivas et al 2007;Roose et al 2007b;Seidler 1996a). Recently, high resolution crystal structures of PSII from the thermophilic cyanobacterium Thermosynechococcus elongatus have been solved, and these include the MSP subunit (Ferreira et al 2004;Loll et al 2005b).…”

Identification and transcriptional analysis of genes involved in Bacillus cereus-induced systemic resistance in Lilium

“…According to the previous studies, PsbR is a 10 kDa extrinsic protein of the photosystem 2 (PS 2) complex and probably has two distinct roles in the function of the PS 2 complex (Suorsa et al 2006, Allahverdiyeva et al 2007, De Las Rivas et al 2007. PsbR clearly stabilizes the PS 2 complex affecting the properties of electron transfer reactions in both acceptor and donor sides (Allahverdiyeva et al 2007, De Las Rivas et al 2007.…”

“…PsbR clearly stabilizes the PS 2 complex affecting the properties of electron transfer reactions in both acceptor and donor sides (Allahverdiyeva et al 2007, De Las Rivas et al 2007. Moreover, PsbR is crucial in providing additional ion concentration for the function of water oxidizing complex, which is likely to occur by stabilizing the binding of PsbP and PsbO proteins in the PS 2 complex (Suorsa et al 2006).…”

Isolation and characterization of photosystem 2 PsbR gene and its promoter from drought-tolerant plant Prosopis juliflora

“…Sequence analysis shows that the N-terminal region of PsbR is highly charged, providing scope to form ion bridges with extrinsic proteins. Thus, the charged domain together with the transmembrane span might make the PsbR protein function as a docking protein (Suorsa et al 2006, De Las Rivas et al 2007.…”