Insights into the function of PsbR protein in Arabidopsis thaliana

: Allahverdiyeva Y, Mamedov F, Suorsa M, Styring S, Vass I, Aro EM

Publisher: ELSEVIER SCIENCE BV

: 2007

: BBA - Bioenergetics

: BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS

: BBA-BIOENERGETICS

: 1767

: 6

: 677

: 685

: 9

: 0005-2728

DOI: https://doi.org/10.1016/j.bbabio.2007.01.011

The functional state of the Photosystem (PS) II complex in Arabidopsis psbR T-DNA insertion mutant was studied. The Delta PsbR 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 Delta PsbR 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 Delta PsbR. 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 Delta PsbR thylakoids. It is concluded that the lack of the PsbR protein modifies both the donor and the acceptor side of the PSII complex. (c) 2007 Elsevier B.V. All rights reserved.