Abstract
Binding properties of the extrinsic PsbO, PsbP and PsbQ in oxygen-evolving photosystem II (PSII) prepared from a green alga, Chlamydomonas reinhardtii, are different from those of spinach PSII1). The green algal PsbP and PsbQ as well as PsbO directly bind to PSII intrinsic proteins independent of the other extrinsic proteins. To search for the nearest neighbor relationship between these extrinsic proteins and PSII intrinsic proteins, we crosslinked Chlamydomonas PSII with a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and then PSII core was prepared by Blue-Native PAGE. Crosslinked products containing PsbO, PsbP or PsbQ were detected in the PSII core by Western blotting using antibodies against these extrinsic proteins, suggesting that each of the three extrinsic proteins interacts electrostatically with different PSII core components. Moreover, crosslinked product between PsbP and PsbQ was found, and its crosslinked site was determined.
1) Plant Cell Physiol. 44 (2003) 76-84