The D1 protein, CP43 and OEC33 are the neighboring polypeptides at the lumenal side of PS II

Abstract

When spinach PS II membranes devoid of Mn cluster and the extrinsic OEC subunits are illuminated, the reaction center D1 protein cross-links with the antenna chlorophyll binding protein CP43, and the cross-linked products are detected by SDS/urea-PAGE and immuno-blotting with specific antibodies [Yamamoto, Y and Akasaka, T., Biochemistry 34, 9038-9045 (1995)]. The cross-linking took place under anaerobic conditions, as well as aerobic conditions, which reflect the nature of the donor-side photoinhibition of PS II. The cross-linking did not occur when the PS II membranes retained the OEC33 or when the OEC33-depleted membranes were reconstituted with the protein. These results strongly suggest that the D1 protein, CP43 and the OEC33 are located closely at the lumenal side of PS II, and support the model for arrangement of these polypeptides proposed on the x-ray diffraction analyses of the crystal structure of PS II from Synechococcus elongatus [Zouni, A. et al., Nature 409, 739-743 (2001)].