title: Insights into the function of PsbR protein in Arabidopsis thaliana.
abstract: The functional state of the Photosystem (PS) II complex in Arabidopsis psbR T-DNA insertion mutant was studied. The DeltaPsbR thylakoids showed about 34% less oxygen evolution than WT, which correlates with the amounts of PSII estimated from Y(D)(ox) radical EPR signal. The increased time constant of the slow phase of flash fluorescence (FF)-relaxation and upshift in the peak position of the main TL-bands, both in the presence and in the absence of DCMU, confirmed that the S(2)Q(A)(-) and S(2)Q(B)(-) charge recombinations were stabilized in DeltaPsbR thylakoids. Furthermore, the higher amount of dark oxidized Cyt-b559 and the increased proportion of fluorescence, which did not decay during the 100s time span of the measurement thus indicating higher amount of Y(D)(+)Q(A)(-) recombination, pointed to the donor side modifications in DeltaPsbR. EPR measurements revealed that S(1)-to-S(2)-transition and S(2)-state multiline signal were not affected by mutation. The fast phase of the FF-relaxation in the absence of DCMU was significantly slowed down with concomitant decrease in the relative amplitude of this phase, indicating a modification in Q(A) to Q(B) electron transfer in DeltaPsbR thylakoids. It is concluded that the lack of the PsbR protein modifies both the donor and the acceptor side of the PSII complex.
authors.affiliation: Department of Biology, Plant Physiology and Molecular Biology, University of Turku, FIN-20014 Turku, Finland.
authors.forename: Yagut
authors.initials: Y
authors.lastname: Allahverdiyeva
authors.forename: Fikret
authors.initials: F
authors.lastname: Mamedov
authors.forename: Marjaana
authors.initials: M
authors.lastname: Suorsa
authors.forename: Stenbjörn
authors.initials: S
authors.lastname: Styring
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004237:Diuron / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D005453:Fluorescence; D005470:Fluorometry; D006540:Herbicides / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000737:chemistry / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D006540:Herbicides; D045332:Photosystem II Protein Complex; C508087:PsbR protein, Arabidopsis; D004237:Diuron; D010100:Oxygen