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Destabilization of the Oxygen Evolving Complex of Photosystem II by Al 3+
Author(s) -
Hasni Imed,
Hamdani Saber,
Carpentier Robert
Publication year - 2013
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12116
Subject(s) - p680 , photosystem ii , thylakoid , chemistry , electron transfer , electron transport chain , quenching (fluorescence) , oxygen evolution , photochemistry , oxygen evolving complex , chlorophyll fluorescence , fluorescence , photosynthesis , biophysics , photosystem i , chloroplast , biology , biochemistry , physics , quantum mechanics , electrode , electrochemistry , gene
The inhibitory effect of Al 3+ on photosynthetic electron transport was investigated in isolated thylakoid membranes of spinach. A combination of oxygen evolution, chlorophyll fluorescence induction ( FI ) and decay and thermoluminescence measurements have been used to characterize photosystem II (PSII) electron transport in the presence of this toxic metal cation. Our results show that below 3 m m , Al 3+ already caused a destabilization of the Mn 4 O 5 Ca cluster of the oxygen evolving complex ( OEC ). At these concentrations, an increase in the relative amplitude of the first phase ( OJ ) of FI curve and retardation of the fluorescence decay kinetics following excitation with a single turnover flash were also observed. A transmembrane structural modification of PSII polypeptides due to the interaction of Al 3+ at the OEC is proposed to retard electron transfer between the quinones Q A and Q B . Above 3 m m , Al 3+ strongly retarded fluorescence induction and significantly reduced F v / F m together with the maximal amplitude of chlorophyll fluorescence induced by a single turnover flash. This chlorophyll fluorescence quenching was attributed to the formation of P680 + due to inhibition of electron transfer between tyrosine 161 of D1 subunit and P680.