EFFECT OF THE MANGANESE COMPLEX ON THE BINDING OF THE EXTRINSIC PROTEINS (17-KDA, 23-KDA AND 33-KDA) OF PHOTOSYSTEM-II

Selective extraction-reconstitution experiments with the extrinsic Photosystem II polypeptides (33 kDa, 23 kDa and 17 kDa) have demonstrated that the manganese complex and the 33 kDa polypeptide are both necessary structural elements for the tight binding of the water soluble 17 and 23 kDa species. When the manganese complex is intact the 33 kDa protein interacts strongly with the rest of the photosynthetic complex. Destruction of the Mn-complex has two dramatic effects: i) The binding of the 33 kDa polypeptide is weaker, since it can be removed by exposure of the PS II system to 2 M NaCl. and ii) the 17 and 23 kDa species do not rebind to Mn-depleted Photosystem II membranes that retain the 33 kDa protein.