Removal of stable tyrosine radical D+ affects the structure or redox properties of tyrosine Z in manganese-depleted photosystem II particles from Synechocystis 6803.

Coordination of proton and electron transfer from the redox-active tyrosine, YZ, of Photosystem II and examination of the electrostatic influence of oxidized tyrosine, YD˙(H+)

“…Similar results were obtained by measurements of charge recombination, where the mutant rate was no more than 10% faster than that of the WT, but where the standard deviations also overlapped (not shown). However, Boerner et al 39 have reported a somewhat faster (by 27%) rate of recombination in the D2-Tyr160Phe mutant than in the WT. Comparing the magnitude of the rates of the oxidation reported here (Fig.…”

Photosystem II: evolutionary perspectives

“…It was thus suggested that it can play a role in oxidizing the low valence states of Mn even in the dark and this may be important for the stability of the cluster in the dark and during photoactivation (Stryring & Rutherford 1987;Vermaas et al 1988). A second role is that, by maintaining its proton close by upon oxidation, it can have an electrostatic effect on the potential and more importantly the location of the chlorophyll cation, P ϩ (Boerner et al 1993;Nugent et al 1994;Faller et al 2001;Ananyev et al 2002). It has recently been shown experimentally that the absence of TyrD does indeed affect photoactivation (and indeed the yield of oxygen evolution) (Ananyev et al 2002).…”

Electronic Structure of Tyrosyl D Radical of Photosystem II, as Revealed by 2D-Hyperfine Sublevel Correlation Spectroscopy

“…In Figure 3a the stronger couplings (peaks H#1 and H#2) are presented in detail. Ridges from two rhombic protons are observed as can be seen from the two long arcs ranging between [2][3][4][5][6][7][8][9][10][19][20][21][22][23][24][25][26][27][28] MHz and [1-10,19-28] MHz, which correspond to two different sets of principal values (say A x , A z ). The small arc in the frequency region [3][4][5][6][23][24][25] MHz, that define the third hyperfine coupling component, A y , does not cross the 1 H antidiagonal in a single point.…”

“…Although Y D does not directly interact with Mn 4 Ca for the water splitting process, it plays important role for the efficient function of PSII [8,16,17,[19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Previous work on Y D -less mutant of Synechocystis PSII showed that the redox properties of Y Z are altered [23].…”

“…Although Y D does not directly interact with Mn 4 Ca for the water splitting process, it plays important role for the efficient function of PSII [8,16,17,[19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Previous work on Y D -less mutant of Synechocystis PSII showed that the redox properties of Y Z are altered [23]. In addition, the replacement of tyrosine D with Phenylalanine affects the proton transfer pathways for the reduction of P + 680 in Chlamydomonas PSII cores [31].…”