Disassembly of Photosystem II Following Photoinhibition
Photosystem II(PS II) of higher plants and cyanobacteria is a multi-protein complex, where the D1 and D2 proteins are thought to comprise the reaction center. According to this model the Dl and D2 proteins are arranged as a heterodimer analogous to the L and M reaction center subunits of photosynthetic bacteria, carrying all the redox components required for the primary photochemistry of PS 11(1,2). In addition, circumstantial evidence suggests that the manganese ions required for water oxidation are associated with the Dl and D2 proteins(3,4). When the photosynthetic app-aratous is exposed to excess light the PS II activity is inhibited, and an increased turnover of the Dl protein is induced. In this study the inhibition of PS II activity and the degradation of the Dl protein has been correlated to other changes in the organization of the PS II complex.
KeywordsCytochrome B559 Extrinsic Protein Primary Photochemistry Manganese Cluster Reaction Center Subunit
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